DEPARTMENT oF - BGU · the analysis of nonlinear dynamic systems, the modeling of desertification,...

DEPARTMENT oFSOLAR ENERGY ANDENVIRONMENTAL PHYSICS

Chairperson: Prof. Isaak Rubinstein

The Department of Solar Energy and Environmental Physics integrates the disciplines of naturalsciences and engineering in the study of the physical environment. Its scientists come from thefields of geography, meteorology, mechanical engineering, applied mathematics, physics andchemistry. Main topics of investigation include: solar energy utilization; applied optics; the desertclimate; remote sensing and modeling of desertification; application of nonlinear dynamics andthermodynamics to the study of environmental processes; mechanics of granular materials;membrane electrochemistry and desalination.

The department provides consultation services to government agencies and municipalities onthe optimal use of solar energy in specific projects, as well as to industrial concerns on thedevelopment of novel solar devices.

Four research groups operate in the department: Environmental Physics; the Ben-Gurion NationalSolar Energy Center; Desert Meteorology; and Remote Sensing.

Phone: 972-8-659-6803 • Fax: 972-8-659-6921 • E-mail: [email protected]

ACADEMIC STAFFBerkofsky, Louis (Professor Emeritus)Biryukov, SergeyBurde, GeorgyFaiman, David1

Feuermann, DanielGitelson Anatoly2

Gordon, Jeffrey M.3

Gutman, Lev (Professor Emeritus, deceased October 2001)Huleihil, MahmoudKarnieli, Arnon4

Katz, EugeneMeron, Ehud1

Offer, Zvi Y.4

Orlovsky, LeahPrigozhin, Leonid5

Rubinstein, Isaak5

Zaltzman, Boris5

Zangvil, Abraham4

Zarmi, Yair2

Zemel, Amos6

ASSOCIATE STAFFIbbetson, Peter7

Siderer, Yona

1 Joint appt. with BGU’s Dept. of Physics2 Permanent appt. with University of Nebraska, Lincoln, USA3 Joint appt. with BGU’s Dept. of Mechanical Engineering4 Joint appt. with BGU’s Dept. of Geography and Environmental Development5 Joint appt. with BGU’s Dept. of Mathematics6 Joint appt. with BGU’s Dept. of Industrial Engineering and Management7 Joint appt. with Tel Aviv University’s Wise Observatory

SOLAR ENERGYPHYSICS 3

The Forest Goldman-SonnenfeldtBuilding for Solar Energy and

Environmental Physics

RESEARCH ACTIVITIES

ENVIRONMENTAL PHYSICSMany processes and phenomena in science, technology and the environment, while appearingat first glance to be unique and unrelated, have common features when examined from themathematical-physical point of view. For example, the formation of sand dunes, river networksand magnetic fields in a superconductor have a common description that uses rather sophisticatedmathematical techniques. In a totally different arena, a special sub-discipline of optics – nonimagingoptics – is being used to design state-of-art concentrators for solar radiation, special illuminationsystems and sunlight-powered surgical tools that replace expensive lasers, as well as tounderstand certain aspects of the mechanism of vision in living organisms. In another example,a common mathematical-physical basis can be used to study water desalination processes andthe physiology of living cells.

The power of the mathematical-physical approach for describing and analyzing environmentalprocesses are being demonstrated by Departmental research ers. Topics under study includethe modeling of climatic phenomena in the desert; the interaction of dust particles with theenvironment and their effect on the climate; the application of optics to solar energy utilization;the analysis of nonlinear dynamic systems, the modeling of desertification, water desalination,and phase change processes; applied thermodynamics; and resource economics under conditionsof uncertainty.

To accommodate the interdisciplinary nature of environmental research, the group is composedof scientists with varied backgrounds in the mathematical and physical sciences.

PATTERN FORMATION AND NONLINEAR SYSTEM DYNAMICSVegetation patterns, such as bands and spots, are major controllers of ecosystem function.They strongly influence water redistribution, biomass production and nutrient dynamics. Thediversity of vegetation patterns is particularly pronounced in drylands due to water scarcity,competition and herbivory. A new model for vegetation dynamics has been developed. Themodel reproduces a wide range of patterns observed in arid and semi-arid regions, includingforms that have not been explained yet, such as rings. The model has been used to study thediversity of vegetation patterns along a rainfall gradient. It predicts transitions from bare soil atlow precipitation to homogeneous vegetation at high precipitation, through intermediate statesof spot, stripe and hole patterns. The model also predicts wide precipitation ranges wheredifferent stable states coexist. These predictions have been used to explain desertification asa hysteresis phenomenon, and to propose a new approach to classifying aridity. The results ofthis study provide insights into the vulnerability of drylands to desertification, the irreversibilityof desertification, and the prospects of human intervention in recovering bioproductivity.With: J. von Hardenberg; M. Shachak, BIDR; E. Gilad, Ben-Gurion University

We introduce a minimal model for the description of dormancy, a survival strategy used bysome bacterial populations that are intermittently exposed to external stress. We focus on thecase of the cyanobacterial crust in drylands exposed to severe water shortage and comparethe fate of ideal populations that are respectively capable or incapable of becoming dormant.The results of the simple model introduced here indicate that under a constant, although low,supply of water the dormancy strategy does not provide any benefit and can instead decreasethe chances of population survival The situation is reversed for highly intermittent external stress,due to the presence of prolonged dry periods intermingled with short periods of intenseprecipitation In this case, dormancy allows for population survival during the dry periods. Bycontrast, bacteria that are incapable of entering into a dormant state cannot overcome thestressful times. The model also rationalizes why dormant bacteria, such as those in the desertcyanobacterial crust, are extremely sensitive to other disturbances such as trampling cattle.With: J. von Hardenberg; M. Baer, MPI, Dresden; A. Provenzale, Institute of Atmospheric Sciences and Climate, NationalResearch Council, Turin, Italy


VEGETATION PATTERNS AND

DESERTIFICATION

MERON, ZARMI

MODELLING THE SURVIVAL

OF BACTERIA IN DRYLANDS:

THE ADVANTAGE OF BEING

DORMANT

MERON

A ringlike pattern of Poa bulbosaobserved in the northern Negev (200

mm mean annual rainfall)

A conspicuous property of systems driven far from thermal equilibrium is the possible appearanceof persistent oscillations. Biological rhythms, such as the heartbeat, provide good examples.The oscillatory systems encountered in nature are usually not isolated and quite often theinteraction with the environment takes the form of a periodic forcing in time, such as Circadianrhythms, entrained by the 24-hour day-night periodicity. Pattern-formation phenomena in suchsystems arise due to multiplicity of phase states in various entrainment resonances. Thesephenomena can best be studied using simpler case models, like oscillating chemical reactionsin controlled laboratory experiments. In a joint theoretical-experimental project we studied theappearance of labyrinthine standing-wave patterns in the 2:1 resonance of a periodically forcedBelousov-Zhabotinsky reaction. Two mechanisms were found experimentally: labyrinths formingby a front instability that leads to fingering and tip splitting, and labyrinths forming by stripenucleation from unlocked oscillations. Both ways of formation have been reproduced in simulationsof the forced complex Ginzburg-Landau equation. Labyrinths forming by a front instability havebeen found within the resonance tongue, close to its high frequency boundary, while labyrinthsforming by stripe nucleation have been found outside the resonance tongue.With: A. Yochelis; A. Hagberg, Los Alamos National Laboratory; A. Lin, Duke University, Durham, NC; H.L. Swinney, Universityof Texas, Austin

Catalytic surface reactions provide a special class of pattern-forming systems where processesoccurring on microscopic (nanometer) and macroscopic (micrometer to millimeter) scales arecoupled together. A common spatial structure appearing in surface reactions is a front separatingdomains with different adsorbate coverage. The direction of front propagation may not be unique.Observations of coexisting fronts propagating in opposite directions have been attributed tofront bifurcations that take single stable fronts into pairs of counter-propagating stable fronts.We studied the effect of anisotropy on pattern formation in bistable systems undergoing frontbifurcations and found two main effects: (i) anisotropy may induce a chaotic state where irregulardynamics are confined to one space dimension, and (ii) in a different parameter range, anisotropymay have an ordering effect, whereby disordered labyrinthine patterns relax toward periodicstripe patterns. The study will be extended along the following lines: 1) the understanding ofadditional mechanisms of pattern formation resulting from anisotropy of diffusion and 2) linkingprocesses at a macroscopic scale (a micrometer and above) to underlying processes at amicroscopic (or nanometer) scale.With: D. Kartoon, M. Baer, MPI, Dresden; R. Imbhil, University of Hanover; M. Eiswirth, Fritz Haber Institute, Berlin; L.Pismen, Technion ≠ Israel Institute of Technology, Haifa

A new mathematical model that describes the segregation dynamics of two distinct populationsin a city has been developed. It associates segregation with an instability of a spatially uniformmixed population state. Segregated states correspond to alternating domains of over-representationand under-representation of a given population. A second instability designates a transition toa stronger form of segregation involving enclaves of pure population. The model is used to studyneighborhood change processes such as displacements of transition zones and tipping pointphenomena. The main significance of the model lies in its conceptual framework, which relatessocio-spatial phenomena to dynamical system and pattern-formation theories.With: H. Yizhaq; B. Portnov, BIDR

High-temperature superconductors have the potential to dramatically increase the power densityof electrical power components because they can carry very high current densities and produceor trap extremely strong fields. Partly, wide implementation of such devices is impeded bydifficulties in predicting the macroscopic behavior of superconductors in realistic situations. Weare extending the existing critical-state models and developing efficient numerical methods fortheir analysis. (Funding: Engineering and Physical Sciences research Council ≠ EPSRC, UK).With: M.D. McCulloch, D. Dew-Hughes, Oxford University; S.J. Chapman, S. Howison, Oxford Center for Industrial andApplied Mathematics


MULTIPHASE PATTERNS IN A

PERIODICALLY FORCED

OSCILLATORY SYSTEM

MERON

PATTERN DYNAMICS IN

ANISOTROPIC BISTABLE

SYSTEMS

MERON

URBAN SEGREGATION AS A

NONLINEAR PHENOMENON

MERON

MATHEMATICAL MODELING

OF BULK 3D

SUPERCONDUCTORS

PRIGOZHIN

A model simulation showing achaotic mixture of twononequilibrium phases

Of the methods for analyzing of linear dynamical systems that are weakly perturbed by nonlinearinteractions, the use of multiple time scales is the most widely used, usually for calculation offirst-order corrections. However, when used for higher-order corrections (as is required in manyproblems of current research interest), the method may lead to incorrect, or trivial, results unlesscertain consistency requirements are satisfied. The intimate relationship between the Lie-algebraicsymmetry structure of the method of normal forms and the requirements for internal consistencyof the method of multiple time scales has been studied. The origin of the consistency requirementswas elucidated and the way to satisfy them outlined.With: P.B. Kahn, Stony Brook University, New York

The method of normal forms had been originally developed for analyzing linear dynamical systemsthat are perturbed by small nonlinear perturbations and can be described by ordinary differentialequations (e.g., equations that describe the temporal evolution of populations). When appliedto partial differential equations that describe, for instance, the propagation of waves in fluids(e.g., Burgers and KdV equations) and to which higher-order perturbations are added, unforeseendifficulties are encountered due to the occurrence of terms known as obstacles to integrability.These terms, when incorporated in the normal form equation, make it nonintegrable, hence theterm obstacles.†An alternative approach – resolving this difficulty by assigning the effect of theobstacles†to the corrections generated in the solution by the perturbations – was studied, leadingto the computation of these corrections either numerically or analytically in asymptotic limits.With: A. Veksler

SYMMETRY METHODS IN PARTIAL DIFFERENTIAL EQUATIONSFor a wide class of physical systems, the leading order nonlinear equation in an asymptoticexpansion is given by an integrable equation, but the equation with higher order corrections canbe shown to be integrable only up to a certain order in an asymptotic sense (asymptoticintegrability). A new approach to applying the Lie-group machinery in the context of asymptoticintegrability has been developed. Application of the approach to extensively studied systems,such as the Korteweg-de Vries (KdV) equation with higher order corrections, allowed us to obtainnew results detailing the influence of the higher order corrections on the solution dynamics inthe underlying physical system. In addition, using the method on the perturbed KdV equationenabled the construction of an integrable nonlinear equation of the same order as the leading-order KdV equation, which nevertheless contains information about the higher-order correctionsif certain conditions are imposed on the parameters of the physical system.

In contrast to the situation for parallel flows, relatively little is known on the linear stability ofnonparallel flows. For a parallel steady-state basic flow, the governing equations of the hydrodynamicstability theory are separable and lead to an ordinary differential equation, the Orr-Sommerfeldequation. For nonparallel and/or unsteady flows (and, in general, all flows occurring in natureand engineering are nonparallel, with many of them being essentially nonsteady), the correspondingoperator does not separate unless certain terms are ignored. The recently developed symmetry-based approach to the separation of variables in linear PDEs with variable coefficients has beenapplied to the problem of stability of nonparallel and unsteady flows. Applying this approach tothe complete equations of the linear stability problem made it possible to define all the nonparalleland/or unsteady flows, for which the stability problem can be reduced to the normal modestability problem. It provides investigators with much wider forms of basic flow for which stabilityanalysis is amenable to analytical solution than are solvable when using common stability theory.With: A. Zhalij, Postdoctoral Fellow, Ben-Gurion University (Institute of Mathematics of the National Academy of Ukraine,Kiev)

Extensions of the classical and nonclassical Lie-group methods of symmetry reduction weredeveloped. The classical method extension is used as a tool for finding changes of variables,which convert the original PDE into another (presumably simpler) PDE. It also provides a newway of defining similarity reductions of a PDE as the singular extended group transformations.It was used to define new similarity reductions of the generalized Boussinesq equations, whichare generic for physically important nonlinear equations. The extension of the nonclassical methodfor finding similarity reductions of PDEs produces similarity reductions unobtainable by classicalor nonclassical group methods. By application of the extended method, new solutions of theboundary layer equations of considerable importance in physics were found.


PERTURBATIVE ANALYSIS OF

NONLINEAR SYSTEMS

ZARMI

THE USE OF THE LIE-GROUP

MACHINERY IN THE CONTEXT

OF ASYMPTOTIC

INTEGRABILITY OF PHYSICAL

SYSTEMS

BURDE

APPLICATION OF THE

SYMMETRY-BASED VARIABLE

SEPARATION METHOD TO

STABILITY ANALYSIS OF

NONPARALLEL FLOWS

BURDE

SOME EXTENSIONS OF THE

SYMMETRY REDUCTION

METHOD

BURDE

THEORETICAL BIOLOGYExperimentally, when the optical path (L) in a photobioreactor is large (10 cm – 1 m), the optimalareal mass-production rate is constant, independent of L. (In a bioreactor, L is the lateraldimension, through which incident light travels, e.g., the depth of an algae pond.) Areal productivity,however, increases sharply when L is reduced to 1-2 cm. We have explained these observations.

In reactors with very small L, the determining factor is the photosynthetic process characteristiccycle time (or Tp, the time from the moment a cell absorbs the required photons until can againabsorb photons). At high culture-density, average irradiance is low, accompanied by Tp valuesas high as 10 ms. Reducing L, the cell-travel time between the dark and illuminated regions ofthe reactor approaches Tp from above. The time cells spend the dark zone is reduced; hence,productivity rises. For large optical paths (above 10 cm), cell travel-time is so much greater thanTp that most of the time is spent in the dark zone. As the travel time between the light and darkregions approaches Tp, the time wasted in the dark is no longer relevant. A simple model explainsthe constancy of areal productivity as L is varied.With: A. Richmond, BIDR

Air movement through plant canopies and heat transfer is important for understanding growthperformance of plants, especially in arid regions where air motion is accompanied by water loss.Past studies have dealt only with uniform canopy covers. We here present the first study a fieldin which plants grow in parallel, separated rows. The stochastic equations that govern the motionof turbulent air eddies were analyzed, generating a detailed description of heat and mass flowin and around the canopy.With: P. Berliner, A. Arazi, BIDR

We formulated and analyzed mathematical models of cell aggregation by chemotaxis. Thismechanism is important in morphogenesis, angiogenesis and the vascularization of solid tumors,as well as in many other biological activities. This work supplements the classical models ofchemotaxis with the notion of maximum packing of cells, which accounts for the fact that cellconcentration may not exceed a certain maximum value. We analyzed the mathematical andbiological consequences of this modification for the existing models of chemotaxis.With: M. Primicerio, University of Florence, Italy

MEMBRANE ELECTROCHEMISTRY AND DESALINATIONThis long-term research project concerns a theoretical and experimental study of ionic transportin electrolyte solutions in relation to membrane electrochemistry, in particular to desalination byelectrodialysis. Our study is concerned with fluid flow at an ion-exchange electrodialysis membraneinduced by nonequilibrium electro-osmosis in the course of concentration polarization of theelectrolyte solution adjacent to the membrane by the passage of an electric current trough it.Previously, we derived a nonequilibrium electro-osmotic slip condition by boundary layer analysisand investigated the linear stability of quiescent ion electrodiffusion through an electrodialysismembrane and the solution layer adjacent to it (diffusion layer), disclosing the possibility of anonequilibrium electro-osmosis-induced instability for realistic conditions. Numerical calculationsthe resulting nonlinear convection showed that the latter provides an efficient mixing mechanismfor the diffusion layer, which accounts for the overlimiting conductance in electrodialysis and therelated noise phenomena – a long-time puzzle in membrane electrochemistry. We are currentlytesting of this theory in experiments carried out by the Desalination Group, led by Prof. OraKedem and Dr. Yoram Oren at BGU’s Institutes of Applied Research.

A major shortcoming of using inexpensive heterogeneous ion-exchange membranes in desalinationby electrodialysis is their high polarizability and the low value of their limiting currents. Experimentsby BGU’s Desalination Group (Prof. Ora Kedem, Dr. Yoram Oren, et al.), has alleviated thisproblem by modifying these membranes with a thin layer of cross-linked polyelectrolyte, slightlycharged with the same sign as the membraneÆ the numerical analysis of a model membraneshowed that adding even a very thin, lightly charged layer of this kind increases the value of thelimiting current to that of the prohibitively expensive homogeneous membranes. A simple limitingmodel was derived to explain this behavior. Analysis of this model showed that the aforementionedproperty of the limiting current is an exact mathematical expression of the funneling of counterionsby the charged layer from the impermeable parts of a heterogeneous membrane to its permeable ones.


QUANTITATIVE ASPECTS OF

MASS CULTIVATION OF ALGAE

ZARMI

HEAT AND MASS TRANSFER

IN PLANT CANOPIES

ZARMI

CELL AGGREGATION BY

CHEMOTAXIS

ZALTZMAN

ELECTROCONVECTION IN

ELECTRODIALYSIS

RUBINSTEIN, ZALTZMAN

ION EXCHANGE ‘FUNNEL’

RUBINSTEIN, ZALTZMAN

RESOURCE MANAGEMENTWe extended our previous studies on the optimal transition to backstop substitutes for naturalresources via R&D investments in alternative technologies to replace conventional resourcesthat are nearing depletion. The resources can be nonrenewable (e.g., fossil fuel reserves) orrenewable (e.g., fresh water supplies). At the present time, solar energy and desalinationtechnologies are expensive and used as alternatives mostly in certain small-scale applications,where fossil energy and fresh water are prohibitively expensive. However, the cost of thesesubstitutes decreases continuously as learning from R&D efforts increases our knowledge base.The R&D optimization problem is embedded within an endogenous growth model, accountingexplicitly for the competition among consumption, capital accumulation and R&D investment.We classify prototypical economies in terms of their production technology, learning ability andtime preferences. Depending on the economy type and capital endowment, we find a widevariety of optimal R&D and capital formation processes, ranging from R&D-induced growth tocases where R&D is unwarranted.With: Y. Tsur, Hebrew University of Jerusalem

R&D aimed at promoting the use of renewable energy technologies typically proceed along twoavenues: gradual improvement of existing technologies so as to reduce their cost and increasetheir market share, and the study of innovative technologies that might dramatically change ourideas on how to utilize solar energy. This review provides a perspective on innovations of thelatter type by describing several novel technologies developed in Israeli research institutes. Itexplains how technologies that differ significantly in scale and approach can contribute to theproduction of clean energy at affordable cost. Examples include the Haifa Technion’s giant WindTowers, the Big Dish recently installed at the Ben Gurion National Solar Energy Center, novelhigh-temperature receivers developed at the Weizmann Institute, as well as smaller scale devicessuch as the minidishes and carbon-based solar cells proposed and investigated at the BIDR.

Agricultural research is typically focused on growing strategies that ensure maximum yield forany specific crop. Economic considerations concern maximum net profits, accounting also forthe costs of the various inputs. This study is motivated by the move to significantly increase thecost of water for agricultural use in order to decrease the demand for irrigation water. Weincorporated the dynamic response of plants to water input within an economic optimizationproblem in order to derive an irrigation policy that entails maximum net profits rather thanmaximum yield. With realistic water costs, this policy produces significant savings in irrigationwater with only a modest reduction in the corresponding yield.With: U. Shani, Y. Tsur, Hebrew University of Jerusalem

THERMOPHYSICS AND APPLIED OPTICSWhile chillers (generalized cooling systems) are complicated entities that have been analyzedonly with massive computer simulations and costly trial-and-error experimental methods, wehave shown how fundamental tools in irreversible thermodynamics can be applied to developrelatively simple, physically transparent tools for predicting, diagnosing and optimizing conventionalchillers. These theoretical results have been tested against extensive experimental data in thelaboratory and more recently have been confirmed in large commercial chiller installations. Ourtext, Cool Thermodynamics (Cambridge International Science Publishing), is being used by fieldengineers, students and researchers in chiller design and diagnostics, and has formed the basisfor new standards for chiller performance by the ASHRAE.With: K.C. Ng, National University of Singapore

Recent advances in the laser cooling of molecular systems to microkelvin and even nanokelvintemperatures beg the question of how the laws of thermodynamics and quantum mechanicsplace fundamental bounds on the rates at which matter can be cooled toward the absolute zeroof temperature. We have shown how the second and third laws of thermodynamics can be usedto establish a fundamental bound for this problem. In modeling molecular refrigerators gearedtoward attaining ultra-low temperatures, only quantum-mechanical, as opposed to classicalphysical models are admissible. We have analyzed a 3-level quantum refrigerator and, in particular,its irreversible thermodynamic performance as the absolute zero is approached.With: R. Kosloff, Hebrew University of Jerusalem


GROWTH, SCARCITY

AND R&D

ZEMEL

INNOVATIVE RENEWABLE

ENERGY RESEARCH IN

ISRAEL: FROM LARGE SCALE

TO SMALL SCALE AND BACK

ZEMEL

IRRIGATION MANAGEMENT IN

A DYNAMIC SOIL-WATER-

YIELD SYSTEM

ZEMEL

THE PHYSICS AND

ENGINEERING OF CHILLERS

GORDON

QUANTUM

REFRIGERATION

GORDON

In many laser fiber-optic surgical methods, there is substantial room for improvement in boththe efficiency of coupling laser light into human tissue, as well as the intensity distribution withwhich the tissue is irradiated. By foregoing optical systems employing conventional imaging andinventing nonimaging mirrors, aspheric lenses and gradient-index devices that are tailored tospecific surgical needs, we can now offer superior optical designs for an assortment of medicaltreatments. Our latest advance is the design and performance of rod lenses where the material’srefractive index can be varied with radial position. This offers a new and important degree offreedom in tailoring laser delivery systems to surgical needs.

On line-simulation of greenhouses can improve the temperature control in commercial greenhousesand provide a better climate for growing produce. Aside from a backup heating system, thefertigation and fertilization of the greenhouse crop is incorporated within the control system. AEuropean consortium of universities and industry, with BGU providing the simulation expertise,carries out this interdisciplinary work. The BGU team has developed a preliminary simulationand control program which has been tested successfully by our European partners on a physicalmodel representing a simple greenhouse. Adaptation of the simulation to a modern greenhousewith all complexities is in progress.

We work with Israeli high-tech corporations in their development of a variety of optical andthermal systems.

SOLAR PHOTONICSSolar photonics refers to the exploitation of the inherent photonic or quantum-mechanical valueof sunlight, in contrast to the familiar and prosaic applications that engender converting solarradiation into heat (hot water, steam production, space cooling and most power generation).Solar photonics embodies a paradigm shift in the way the value of sunlight is perceived: insteadof its being regarded as an energy saving resource, we primarily relate to using solar radiationfor saving lives (in medical procedures) or for producing extremely valuable materials such asin nanotechnological applications. These are instances where immense photon densities arerequired, as well as wavelengths within the solar spectrum. Attaining the requisite photon densitiesdemands innovations in the concentration and remote delivery of sunlight in pragmatic ways.Three projects described below comprise our current solar photonics initiatives, all of which arebeing advanced both in theoretical studies and experimental realizations.

Laser fiber-optic surgery encompasses a successful, proven, minimally invasive class of medicalprocedures, of which much of the world’s population is deprived due solely to the exorbitantprice of this surgical device. The expensive laser is an uncontested tool because even thehighest-brightness conventional lamps fall far below the brightness levels required for surgery.But the surface of the sun has a power density of the same order as surgical lasers, with theadded benefit of a broad-spectrum (photonic) source that could actually be more favorable formany medical procedures. We have established the scientific and engineering basis forconcentrating sunlight to ultra-high levels, coupling these immense power densities into opticalfibers, and delivering the light into human tissue. Solar surgery is an exciting example of solarphotonics in a unique application: saving lives instead of energy. We are currently working onthe experimental realization of solar surgery: building and testing the solar fiber-optic concentratorunits and, in the near future, commencing experiments on biological tissue.

Photovoltaic power generation is gravitating toward two extremes. One comprises relatively low-efficiency but inexpensive solar cells. The other constitutes high-efficiency, expensivesemiconductors, where solar cells are tailored to progressively higher efficiency at elevatedphoton densities (which requires highly concentrated sunlight). An additional advantage of highlyconcentrated light is its use of so little photovoltaic material per unit of solar collection area thatthe seemingly expensive solar cells represent only a small fraction of the costs. The total systemthus becomes affordable. We have developed a new approach predicated upon the miniaturizationof the collector unit: a tiny paraboloidal dish (e.g., with a diameter of the order of 10 cm), whichconcentrates sunlight into a short glass rod. The flux distribution of the transported light ishomogenized in a miniature glass kaleidoscope that is optically coupled to a small high-efficiency


BIOMEDICAL OPTICS

FEUERMANN, GORDON

GREENHOUSE INTEGRATED

SYSTEM

FEUERMANN, HULEIHIL

CONSULTATION FOR ISRAELI

HIGH-TECHNOLOGY

INDUSTRIES

FEUERMANN, GORDON

SOLAR SURGERY

FEUERMANN, GORDON,

HULEIHIL

MINIATURIZED HIGH-

CONCENTRATION

PHOTOVOLTAIC POWER

GENERATION

FEUERMANN, GORDON

Minidish fiber-optic solar-lightconcentrator

Ex-vivo solar surgery on chickenlivers (l.: after a few seconds of

exposure; r.: about a minute later)

solar cell. The cell resides behind the dish and can be cooled adequately with a passive heatsink. These nominally independent collection units can be assembled into modules and arraysthat produce almost any prescribed power level. All system elements are predicated on existingtechnologies.

Carbon nanomaterials such as fullerenes and nanotubes are being explored for a host of promisingapplications ranging from semiconductors to molecular delivery of drugs and diagnostic reagents.Their market price ranges from $100 to $1000 per gram (far higher, for example, than gold ordiamond). To a large extent, the excessive prices stem from inherently high production costs,due to processes that require temperatures in excess of 3000oK. We are currently designingsolar photonic systems for the synthesis of these lucrative carbon nanomaterials, which involvethe production of inordinately high photon densities from sunlight with innovative opticalconcentrators and the generation of nanomaterials in controlled, indoor reactors. In thesesystems, the solar facility and reactor configurations are tailored to one another optically, thermally,chemically and mechanically. At current prices, a new level of solar profitability is possible –orders of magnitude higher than any solar application developed to date. Alternatively, solarphotonics for nanotechnology could result in far lower production costs and hence affordablematerials. Again, this is an example of solar photonics placing a completely different perspectiveon the value of sunlight, which takes unique advantage of the photonic value of solar radiation.With: M. Levy, Weizmann Institute of Science

REMOTE SENSINGRemote sensing is a cost-effective method for gathering large amounts of information characterizingvast expanses of unsettled lands, using satellite, aerial imagery and ground data. Of particularimportance is the study of environmental changes taking place in dry lands, such as desertificationand climate change. Conventional survey methods require considerable investments in manpowerand are not always practical such vast, unpopulated areas.

The Remote Sensing Laboratory is manned by an interdisciplinary research group. Itsresearchers develop scientific theories, methodologies, and applications in remote sensing,image processing and Geographic Information System (GIS) management of the earth’s resources.Working with other BIDR researchers, members of the group apply airborne and spaceborneimagery and ground data to environmental problems, with special emphasis on dry lands.

The Laboratory has two long-term collaboration agreements with NASA Headquarters:1) Routine monitoring of aerosol properties and surface spectral properties, and conducting

short field experiments in order to relate these measurements to space observations;2) Exploitation of ocean color data from the SeaWiFS program. This later agreement enables

the Laboratory to receive, store and analyze digital data from the SeaWiFS satellite.

In arid environments, where the higher plants are sparse, biogenic crusts have considerableimportance in the overall production of the greenness signal detected by remote sensing. Inthese measurements, crust-covered areas are visually similar to bare soil throughout the dryperiod. Our findings show that the temporal analysis of natural vegetation in semiarid regionsshould take into account the three ground features – annuals, perennials, and biogenic crusts– in a way that is not commonly considered either in agricultural areas or in humid regions. Inarid areas, the three phenological cycles should be studied separately. (From the remote sensingpoint of view, the biogenic crusts of microphytic communities can be considered as soil duringthe dry season and as vegetation during the wet season.) We are calibrating and validatingspectral models and remote sensing equations for maximum discrimination of sparse arid andsemiarid vegetation and of ground features.

Unsuccessful efforts to interpret and analyze several sets of images acquired over Israel byLandsat-7 motivated us to examine the hypothesis that image data acquired over the desertregions along the climatic transition zone of Israel are subject to radiometric saturation. We arepresently characterizing the saturation phenomenon by inspecting different images of Landsat-7 and hope to suggest a statistically based methodology for overcoming this problem. Entropyanalysis was also performed on these images in order to compare the information content ofthe Landsat-7 ETM+ sensor over the desert environment with that of the Landsat-5. The study


SOLAR PHOTONICS FOR

NANOTECHNOLOGY

FEUERMANN, GORDON,

KATZ, HULEIHIL

REMOTE SENSING

TECHNIQUES SPECIFIC TO

VEGETATION DETECTION IN

ARID REGIONS

KARNIELI

LANDSAT SATURATION

KARNIELI

reveals that radiometric saturation affected different ETM+ bands. Consequently, in terms ofentropy, less information can be extracted from the saturated bands relative to equivalent bandsof Landsat-5 TM. A statistical solution, based on multivariate correlation analysis among allspectral bands, was proposed to overcome the saturation problem. Satisfactory results wereachieved by applying the statistical methods on several samples of saturated scenes. However,an operational revision in the spectral radiance range and gain setting applied to Landsat-7ETM+, in effect since July 1, 2000, has improved the saturation phenomenon over the region.

Dust is a dominant feature in satellite images and is suspected to produce a large radiativeforcing of climate. While remote sensing of dust over the dark oceans is feasible, adequatetechniques for remote sensing over the land still have to be developed. Here, similar to theremote sensing of aerosols over vegetated regions, we use a combination of visible and mid-IR solar channels to detect dust over the desert. Results show that the aerosol optical thicknessτ can be derived within accuracy ∆τ=0.5 for the range of 0<τ<=2.5, thereby enabling the detectionof dust sources and the estimation of three to five levels of dust opacity over the desert. Themethod is very sensitive to the nature of the dust absorption, which must be accurately determined,and is equally sensitive to dust in the entire atmospheric column. It is best applied in the redpart of the spectrum (around 0.64 µm) where dust was found to be weakly or nonabsorbing.We plan to use this method as part of the dust monitoring via the MODIS instrument on NASA’sEarth Observing System satellite.With: Y.J. Kaufman, NASA, Greenbelt, MD; D. Tanré, University of Lille, France

Aircraft measurements using a field spectrometer over a variety of ground surfaces in Israelreveals that under clear sky conditions, the SWIR (short wavelength infrared) spectral bandsaround 1.6 and 2.1 µm are highly correlated with the visible – blue, green, and red – spectralbands. Empirical linear relationships – such as ρ0.469 = 0.25ρ2.1; ρ0.555 = 0.33ρ2.1; ρ0.645 = 0.5ρ2.1;and ρ0.645 = 0.66ρ1.6 – were found to be statistically significant and consistent with previousfindings. Based on the above relationships, two new vegetation indices are proposed. Theseare AFRI1.6 = (ρNIR – 0.66ρ1.6)/(ρNIR + 0.66ρ1.6) and AFRI2.1 = (ρNIR– 0.5ρ2.1)/(ρNIR + 0.5ρ2.1). It wasshown that under clear sky conditions, the AFRI indices (and especially AFRI2.1) closely resemblethe NDVI (normal difference vegetation indices), and their values are almost identical. Theadvantage of the derived AFRI indices is based on the ability of the SWIR bands to penetratethe atmospheric column even when aerosols, such as smoke or sulfates, exist. Consequently,these indices have a major application in assessing vegetation in the presence of smoke,anthropogenic pollution or volcanic plumes. This was demonstrated by applying the AFRI for abiomass burned forest in Brazil.

In Central Asia, large-scale anthropogenic changes lead to the formation of new sites from whichdust originates, such as the exposed, dried bottom of the Aral Sea. Much of this dust has a highsalt concentration (up to 70%) and is contaminated with pesticides and heavy metals. Windtransfer of this salty dust leads to the formation of salty crusts in adjacent areas, a steadyreduction in land (arable and rangelands) productivity, increased salinization of water resources,as well as negative effects on public health. This study of salty dust storms in the Aral Sea region,based on remote sensing data, has two separate objectives: 1) identifying salty dust-producingplaces in order to elaborate ameliorative measures to prevent the wind from raising the salt/dustand producing salty-dust storms; and 2) monitoring of salty dust storm events. At the first stagethe developed algorithm for detection of the most active sources of dust can be applied usingthe high spatial resolution Landsat TM and ETM+ images, while the monitoring of the salt-dustevents is carried out via the high temporal resolution images from the NOAA AVHRR sensor.


DETECTION OF DUST

OVER DESERTS

KARNIELI

DEVELOPMENT AND

IMPLEMENTATION OF AN

AEROSOL-FREE

VEGETATION INDEX (AFRI)

KARNIELI

SALTY DUST STORMS

IN THE ARAL SEA

BASIN

ORLOVSKY

DESERT METEOROLOGYDesert climates in general and the Negev desert in particular are under investigation. Topicsstudied include classical dynamic meteorology, climatology, dew and dust dynamics, as well asnonlinear partial differential equations (PDEs) that model the underlying physical systems understudy. Control of geohydrological pollution is also of interest to group researchers. Investigationsof the structure and dynamics of atmospheric circulation systems and their spatial and temporalvariations is emphasized, in particular, the structure, motion and trajectories of Mediterraneandisturbances and the importance of the large-scale moisture field in these processes; atmosphericfronts and their effects on regional rainfall; water vapor recycling and its effect on climate; globalclimatic change and El Niño and their effects on the weather and climate in Israel. In addition,the contribution of air circulation to feeding cyclones with the moisture required for rain formationis under study, with emphasis on the basic mechanisms and how they influence the hydrologicalcycle and on climatic change. This work is part of the Global Energy and Water Cycle Experiment(GEWEX), a component of the World Climate Research Program. Special mechanisms of rainformation are probed experimentally and by mathematical modeling.

Other areas of research include: 1) the interaction of atmospheric dust with ecological systemsand the erosion, transport and deposition of atmospheric dust both by theoretical modeling andwind tunnel simulations (research of practical relevance to agriculture, solar energy exploitation,road transport and environmental conservation); 2) dew formation; 3) solar radiation fluctuations;and 4) the theoretical modeling of how the atmosphere effects heat stress in humans.

Departmental members conduct both routine and special meteorological and dustmeasurements in the Negev desert at ground level as well as at several meters above groundlevel at six major dust collection stations (Sede Boqer, Shivta, Avdat, Mashash, Sayeret-Shakedand Beer-Sheva).

Our meteorologists are part of the global Baseline Surface Radiation Network (BSRN), incollaboration with the World Meteorological Organization (WMO) and the Israel MeteorologicalService. Sede Boqer is one of 20 stations around the world selected for long-term monitoringof solar radiation.

Precipitation recycling is the land-atmosphere feedback mechanism through which a fractionof the moisture evaporating over a given continental region falls back as precipitation over thesame region. We developed a new analytical recycling model that incorporates both two-dimensional effects (including those of atmospheric flow) and the effects of flux inhomogeneity.The new model provides improved estimations of precipitation recycling as compared with theexisting models, while retaining the advantages of an analytical representation. The improvedestimations of precipitation recycling for land regions provided by the model are important fora variety of hydroclimatological problems. These might include clarifying how vegetation influencesclimate, whether deforestation or afforestation appreciably affect rainfall; or determine theatmospheric circulation features leading to prolonged, anomalous dry or wet conditions.

The improved recycling models developed by Burde and coworkers in 1996 and 2001 have notyet been used to obtain improved estimations of precipitation recycling for particular land regionsbased on the monthly prevailing regional flow fields. Only sample calculations of some of thebasic flow fields have been carried out. This preliminary work is being extended by includingobservational data for specific land regions in the improved theoretical models. Further improvementsand generalizations of the models are also under way. In particular, the assumption of a fullymixed atmosphere is being modified to include the possibility of a two-dimensional nonuniformmodel, a situation implying incomplete vertical mixing in the tropospheric column.


A NEW MODEL FOR

ESTIMATING REGIONAL

PRECIPITATION RECYCLING

BURDE, ZANGVIL

IMPROVED REPRESENTATION

OF PRECIPITATION RECYCLING

AND ESTIMATIONS OF

RECYCLING RATIOS FOR

VARIOUS LAND REGIONS

BURDE

Dust collection devices mounted atdifferent levels at the BIDR

meteorological observation center

Because of the impact of cyclones and cyclone tracks on local climate – and on atmosphericcirculation in general – the analysis of cyclone tracks is a topic of active research in meteorology.The most widely used method in cyclone track analysis involves following centers of minimumpressure on surface synoptic charts. On occasion, centers of maximum relative vorticity orsatellite cloud images have been used for this purpose. However, in all these approaches thereis no clear distinction between stationary and transient disturbances. For example, if track analysisis performed in the usual manner over the eastern Mediterranean region in the summer, onlystationary low-pressure systems appear in certain locations, such as over Cyprus or Iraq. Wedeveloped a method to filter out stationary disturbances in the synoptic data, enabling transientdisturbances to be discerned. We also investigate the relationship of these disturbances to localweather. Very large data sets of meteorological variables at several elevations extending overtwo decades in the European and Mediterranean areas were used in this comprehensive study.With: S. Karas, Ben-Gurion University

We are continuing and extending our studies on analyzing transient synoptic disturbances anddisturbance tracks over the Mediterranean Sea and vicinity. Our new method of analysis oftransient disturbances (TRADs) is being applied to a detailed study of synoptic disturbancesassociated with a semipermanent low pressure trough extending from the Sudan to Israel duringthe fall, winter and spring months. Preliminary results indicate that most of the transientdisturbances originate in the Mediterranean Basin and not in the Red Sea itself. Also, two typesof Red Sea Troughs (RSTs) have been identified: a dry RST and a wet RST; the former isaccompanied by an upper high-pressure system, while the latter by an upper low-pressuresystem.With: Y. Zvieli

The atmospheric moisture budget of a given continental region is a complex function of themeteorological and hydrological processes within the region and surrounding areas, as well asof soil characteristics and land use. We are studying the relationship between various moisturebudget components and precipitation. The main dynamical processes reflected in the moisturebudget are water vapor storage and the horizontal and vertical advection of moisture within theregion. All these interact in several ways with the inflow and outflow of water vapor at the region’svertical and horizontal (the earth’s surface) boundaries. In this study, we calculate moisturebudget components using measured meteorological data from a region of about one million km2

over the central USA and compare them with parallel calculations from data in Israel and thevicinity. We are attempting to better understand the relationships between moisture budgetcomponents and precipitation. This study is part of an ongoing joint effort with the CooperativeInstitute for Mesoscale Meteorological Studies of the University of Oklahoma.With: D.H. Portis, P.J. Lamb, University of Oklahoma, Norman

Precipitation over a given region is generally derived from moisture advected into the region bywinds, as well as from that evaporating off the region’s surface. The contribution of localevaporation to local precipitation, called†recycling,†may provide a feedback mechanism betweenland-surface processes and precipitation, which may be reflected in the moisture budget of theregion. In this context, the contribution of local evaporation in a given continental region is studiedby two different approaches – observationally, by extending the conventional moisture budgetcalculations, and theoretically, by extending Budyko’s one-dimensional equation to two dimensionsand by other theoretical considerations. We developed a fluid dynamics approach to thequantification of the precipitation recycling process, which includes the role of atmospheric flowstructure. The new approach improves the estimation of precipitation recycling and also enablesthe incorporation of atmospheric flow structure into the feedback mechanisms in hydrologicaland climatological processes.


WATER VAPOR BUDGET

COMPONENTS OVER

CENTRAL NORTH AMERICA

AND ISRAEL IN RELATION TO

PRECIPITATION

ZANGVIL

COMPARATIVE ANALYSIS OF

DISTURBANCE TRACKS OVER

THE NORTHERN RED SEA

ZANGVIL

A COMPARATIVE ANALYSIS OF

DISTURBANCE TRACKS OVER

THE MEDITERRANEAN

REGION

ZANGVIL

OBSERVATIONAL AND

THEORETICAL STUDIES OF

WATER VAPOR AND

PRECIPTATION RECYCLING

BURDE, ZANGVIL

DYNAMICS OF AIRBORNE PARTICLESThe efficiency of six aeolian dust samplers was tested via wind tunnel experiments and fieldmeasurements. The horizontal dust flux samplers were: the Big Spring Number Eight sampler(BSNE), the modified Wilson and Cooke sampler (MWAC), the suspended sediment trap(SUSTRA), and the wedge dust flux gauge (WDFG). Vertical deposition flux was measured usinga marble dust collector (MDCO). A modified Sartorius Membranfilter SM 16711 dust samplerwith adjustable flow rate (SARTORIUS) was used as isokinetic reference sampler. The mostefficient samplers were the MWAC, followed by the BSNE and the SUSTRA. The WDFG is moreeffective than the BSNE at velocities below 3 m/s, but its efficiency drops quickly at higher windspeeds. The most recommendable sampler for field measurements is the BSNE, because itsefficiency varies very slightly with wind speed. In the absence of horizontal flux samplers, theMDCO collector can be used as an alternative to assess horizontal dust flux and airborne dustconcentration provided that appropriate calibrations are made.With: D. Goossens, Leuven University, Belgium

Aeolian erosion of natural dust on two types of hills located in a rocky desert was investigatedby wind tunnel simulations and field measurements. The wind tunnel and field experiments werein good agreement: the greatest dust erosion was observed on the windward hillslopes, andmore particularly on their upper segment, close to the top. The greatest erosion occurred at orimmediately below the top. Downwind of the top, on the leeslope, erosion drops considerably.However, it remains important along the whole leeslope and is clearly visible in the valley floors,although erosion is low there. The areas most sensitive to wind erosion are accurately reflectedby the wind tunnel simulations.The deposition of natural dust in the northern Negev desert was investigated in detail both inthe wind tunnel and in the field. The wind tunnel and field results show a high degree of agreement.More dust settles on the windward than on the leeward slopes, which is in contradistinction tothe widespread wind shadow concept, which would predict more dust falling on the wind-protected leeward slope.With: D. Goossens, Leuven University, Belgium

Airborne dust concentration, measured by total particulate ultra-high-volume sampling at a heightof 1 m, was of the order of 120 µg/m3 (based on 24-h measuring intervals) on the average, withhigher values during the day than at night. Concentrations were also higher during spring andautumn compared to summer and winter. Systematic oscillations with a periodicity of 30 monthsoccur in the concentration curves. Dust accumulation, measured in marble collectors installedat ground level, was of the order of 10-25 g/m2/month, with an average value of 17.1 g/m2/month.The accumulation rate was higher during the daylight hours than at night. Most high-magnitudedust events (defined in this study as events with an average airborne dust concentration> 400 µg/m3) occurring at Sede Boqer are true dust storms, which occur predominantly duringthe daylight hours. The occurrences of dust storms and dust hazes over the year differ: theformer is mainly concentrated between November and May, whereas the latter occurs anytimeduring the year.With: D. Goossens, Leuven University, Belgium

Dust of the northern Negev desert has been studied by the granulometric analysis of monthlycollected samples obtained at 1 m and 3 m above the ground, yielding novel findings concerningdust composition. In particular, significant amounts of clay-size (<16 µm) silt-size (between 62and 16 µm) and sand-size (>62 µm) grades were observed. In the Negev desert, severe duststorms, with airborne dust concentrations greater than 3000 µg/m3, are generally associatedwith migrating synoptic systems and with winds prevailing from the westerly quadrant. Windspeeds during storms are high (over 15 m/s) and relative humidity is low (30-40%). The majormineral constituents of the airborne dust are quartz and calcite; the minor constituents aregypsum and halite, with traces of plagioclase, kaolinite and illite. Many individual dust grains areaggregates of even finer particles. The major elemental constituents are Si and Ca; the minorconstituents iare Al, Mg and Fe and occasionally Na and Cl; the trace elements include Mn, Ti,K, S and P. The storm wind blew over more than 100 km of alluvium and dunes, chalk, limestone,marl, clay and chert. The relative abundance of Si and Ca is characteristic of the nature of the storm.With: E. Azmon, Ben-Gurion University


WIND TUNNEL AND FIELD

CALIBRATION OF AEOLIAN

PARTICLE SAMPLERS

OFFER

AEOLIAN DUST EROSION AND

DEPOSITIATION ON HILLS:

WIND TUNNEL SIMULATIONS

AND FIELD MEASUREMENTS

BURDE

AEOLIAN DUST DYNAMICS IN

THE NEGEV DESERT

BURDE

COMPOSITION OF SETTLED

DUST IN THE NORTHERN

NEGEV DESERT

OFFER

THE BEN-GURION NATIONAL SOLAR ENERGY CENTERProf. David Faiman, Director

The Ben-Gurion National Solar Energy Center houses five laboratories, each of which studiesone or more aspects of solar energy conversion.

The Photon Energy Transformer & Astrophysics Laboratory (PETAL) is centered on the recentlybuilt 400 sq.m parabolic dish multipurpose research facility. Studies are in progress aimed atusing this device for investigating concentrator photovoltaics during the day and gamma-rayastronomy at night.

The Photovoltaic Advanced Materials Laboratory (PAMAL) studies novel materials with potentialsolar energy applications. Our current research efforts focus on various methods to producehigh-efficiency solar cells from fullerene, an unusually structured form of carbon.

The Parabolic Trough Laboratory (PATROL) contains a 960 sq.m oil-heating loop of Luz LS-2collectors (currently being refurbished), and 2760 sq.m of LS-3 collectors with tilted axes, originallydesigned by Luz for direct steam generation. Current work aims at using the LS-2 loop to testreceiver tubes, newly developed by Solel Corp, and the LS-3 loop to investigate certain aspectsof systems that use these tubes.

The outdoor Photovoltaic Test Laboratory (PVTEL) studies the aging of solar panels and associatedsystem components under conditions of desert usage. The special climatic conditions at SedeBoqer enable this facility to be used for unusually precise evaluation of solar cell performance.

The Meteorological Data Laboratory (MEDAL) monitors solar radiation in a variety of spectralbands and geometrical configurations, along with several other meteorological parameters. TheLaboratory is the base station for the ongoing Negev Radiation Survey, which aims at identifyingoptimal locations for future solar power plants and establishing a data base of climatic parametersfor their design.

The Center’s research program includes studies of solar radiation, novel materials for photovoltaicdevices, photovoltaic module characterization, photovoltaic system design and testing, solar-thermal research and dust prevention studies. Colleagues in Ben-Gurion University’s Departmentof Physics and other laboratories in Israel and overseas are involved in several of these researchprojects. The Center organizes and hosts the Sede Boqer Symposia on Solar Electricity Production.It also runs a public outreach program in the form of audio-visual presentations and a guidedtour of the systems.

Phone: 972-8-659-6934 • Fax: 972-8-659-6736 • E-mail: [email protected]


Polycrystalline silicon photovoltaicmodule from Italy under test at the

Solar Energy Center

RESEARCH ACTIVITIES

This is an ongoing effort to fabricate solar cells from C60, the novel fullerene form of carbon.One aspect of this work involves the use of high-quality thin films of C60 which are now grownin our own vacuum laboratory, using a newly developed, patented technique we designed. Theelectronic properties of these films are studied in Sede Boqer, Beer-Sheva, at Tel Aviv University(Prof. Yoram Shapira’s group), and the Hebrew University of Jerusalem (Prof. Isaac Balberg’sgroup) and the films are used to make inorganic photovoltaic devices. This year we have dopedC60 thin films by electrodiffusion of metals, thereby producing high efficiency solar cells. Anotheraspect of this work, performed in collaboration with universities in Austria, Italy, the Netherlands,Spain and Sweden, involves photovoltaic characterization of plastic solar cells employingfullerenes embedded in conjugated polymers. (Funding: Israel Ministry of National Infrastructures)

Work begun in 1999 was continued through 2001 in collaboration with Solel Solar Systems Ltd.in order to refurbish the LS-2 loop at Sede Boqer and rebuild the long-neglected Luz "DSG"system. The former was used to test a number of newly developed advanced components.(Funding: Belfer Foundation; Israel Ministry of National Infrastructures)

Our studies involve photovoltaic (PV) modules which feed a variety of electrical loads (specifically,the electricity grid or zenar diodes). Several times a year, the modules are disconnected fromtheir loads, cleaned, and characterized by a uniquely accurate method that owes its existenceto the natural AM1.5 spectrum (a climatic rarity) that exists at Sede Boqer on clear days for afew hours around solar noon. This spectrum allows us to measure cell efficiencies to an accuracyof 1%. In this manner, the time-dependence of module degradation due to such phenomenaas the so-called "EVA-browning" was again quantified during 2001. Stability tests continued onseveral examples of new-technology PV modules. These include multijunction amorphous Si,CdTe and CIS thin-film cells. We also evaluated the stability of Graetzel cells in long-term outdoormeasurements. (Funding: Israel Ministry of National Infrastructures; Ormat Industries; ECN-Netherlands Energy Research Foundation, 4th EU Framework Programme)With: B. Medwed

This ongoing study aims to establish a database of solar radiation components and other relevantmeteorological parameters in order to permit the optimal design of future solar power plants andto predict their economic viability. Data are provided by the Israel Meteorological Service fromnine stations in the Negev (Arad, Beer-Sheva, Besor Farm, Eilat, Hatzeva, Sede Boqer, Sedom,Yotvata, Mitzpe Ramon), and processed into user-friendly form at Sede-Boqer. A CD-ROMcontains a set of TMY (typical meteorological year) files, based on up to 8 years of data, for eachsite. In addition, the CD-ROM contains all of the raw data from each of the sites, for those whowish to use this information for other scientific purposes. Another aspect of our radiation studiesinvolves (in addition to the routine monitoring of various parts of the solar spectrum andmaintenance of instruments), the development of calibration methods and various instrumentstudies. It includes, specifically, the development of a calibration technique for ultraviolet lightsensors, which permits hourly and seasonal corrections to be made to instrument readings.(Funding: Israel Ministry of National Infrastructures)With: B. Medwed; A. Israeli, V. Liubansky, I. Seter, Israel Meteorological Service

This ongoing international collaboration program within the International Energy Agency(IEA) involves the dissemination of information on photovoltaic (PV) systems among its variousmember countries, as well as case studies involving establishment in desert areas of 1 GW PVpower stations for connection to the power grid. The investigations include technical studiesof the optimal employment of PV modules, in addition to the plant’s potential economic benefitsto the host country. Israel's principal potential interest in VLS-PV (Very Large Scale PV) systemswould be for their future use in the Negev, taking advantage of Israeli non-PV components and/orsystem design know-how and especially – of the use of very large parabolic dishes to irradiatecomparatively small areas of PV material. During 2001, the first computer simulations were runon the expected performance of various kinds of VLS-PV systems in the Negev. (Funding: IsraelMinistry of National Infrastructures)


DATA PROCESSING FOR THE

NEGEV RADIATION SURVEY

FAIMAN, FEUERMANN,

IBBETSON, ZEMEL, MEDWED

PHOTOVOLTAIC RESEARCH

WITH C60 CRYSTALS AND

THIN FILMS

FAIMAN, KATZ

SOLAR-THERMAL RESEARCH

WITH PARABOLIC TROUGH

COLLECTORS

FAIMAN

PHOTOVOLTAIC PV

MODULE AND

COMPONENT STABILITY

FAIMAN

INCLUDING ISRAELI KNOW-

HOW IN IEA PLANNING

PROGRAMS OF VERY LARGE

PV POWER PLANTS IN

DESERTS

FAIMAN

FOR’DRY-CLEANING

SOLAR-COLLECTOR

SURFACES

BIRYUKOV

DIRECT OBSERVATION

OF CLOUDS

BIRYUKOV

PETAL: HIGH-FLUX

PARABOLIC DISH SOLAR

CONCENTRATOR

FAIMAN, BIRYUKOV


This project is part of an ongoing study to develop an alternative to water for cleaning dust fromthe mirrors of solar power stations. We solved the problem of dry deposition by means of anelectric field, which protects surfaces from airborne dust and cleans them (USA Patent No6076216: US006076216A, granted on June 20, 2000). The method uses very little energy andis capable of cleaning large collector areas. We are now addressing the problem of keepingwetted surfaces free of dust under conditions of high relative humidity. Frequency-dependentinteractions, such as dielectrophoresis, are under investigation for this purpose.

Current approaches for protecting solar power plants from the deleterious effects of suddensun-shading caused by passing clouds are ineffective. The signals indicating that action isnecessary appear as feedback at the actual moment of shading – and not before. For theeffective smoothing of such transitional effects, the corrective signal should be the result ofmonitoring and anticipating cloud formation and movement. We solved the technical problemof how to view cloud motion in the vicinity of the sun using a computerized video camera. Byusing algorithms for image-sequence analysis, we precalculate automatically the moment ofshading. This research aims at creating a knowledge-based expert-system that will providecontrol instructions for the optimal, safe operation of large solar power plants under cloudyconditions. A computer armed with such a system would periodically review video images ofthe sky from cameras situated in the vicinity of solar power plants, providing real-time optimalcontrol strategies for the plant operators. In 2001, we successfully demonstrated the operationof our algorithm and its sun-tracking capabilities, detecting relative cloud motion with a complexof cameras and a personal computer.

One approach to utilizing solar energy as a source of low-cost electric power will be to collectsolar energy with PETAL – our large (25-m diameter), sun-tracking, parabolic dish concentrator– and to concentrate the energy onto a small photovoltaic power conversion unit. In a secondapproach, we will position a solar thermal turbine at the focus of the dish. During 2001, a specialtripod was designed and fitted in order to enable installation of either of these units at the focalpoint of the dish. (Funding: Israel Ministry of National Infrastructures)

During 2001, the spatial distribution of concentrated solar flux of PETAL was measured byregistering sunlight intensity scattered by airborne particles in the focal region. We also measuredthe optical quality of individual panels while tracking the sun. Distribution of the intensity of light(the flux map) scattered by a white matt screen in the focus was measured. Statistics of theparameters of flux maps and coordinates of their centers of mass on the screen were usedto analyze the relative contribution of different sources to the resulting response function ofPETAL. The superposition of 36 normalized flux maps gave us an adequate, large-scale measureof the optical quality of the entire dish. Analysis of spatial distributions of light trajectories betweencenters of maps on the screen and centers of the corresponding mirror panels enableddetermination of the focal length of PETAL.

PETAL solar concentrator

RESEARCH INTERESTS

Ph.D. Joint Institute for Nuclear Research, Dubna, 1995; Researcher Grade BApplied solar energy; System design and analysis of system performance; Influence of environmenton thermal and photovoltaic conversion efficiency; Aerosol physics; Hydrodynamics, electrostaticsand electrodynamics of interactions between windborne dust and collector surfaces.Phone: 972-8-659-6737 • Fax: 972-8-659-6736 • E-mail: [email protected]

Ph.D. Perm University, USSR, 1972; Associate ProfessorDynamic meteorology; Fluid dynamics (boundary layer theory, hydrodynamic stability, numericalmethods in fluid dynamics, multiphase flows, environmental fluid dynamics); Heat and masstransfer; Convective stability; Partial differential equations of mathematical physics.Phone: 972-8-659-6847 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. University of Illinois, 1969; ProfessorApplied solar energy; Radiation measurement; Spectral studies; Photovoltaic materials, devicesand systems; Solar-thermal systems.Phone: 972-8-659-6933 • Fax: 972-8-659-6736 • E-mail: [email protected]

Ph.D. Ben-Gurion University, 1985; Senior Lecturer.Application of nonimaging optics to illumination and irradiation problems in high-tech industry;Analysis of closed-system greenhouses; Energy in buildings; High-flux infrared radiation andpractical, compact solar energy concentrators (which approach the thermodynamic limit tooptical concentration); Tailoring illumination optical systems to prescribed flux distributions atmaximum radiative efficiency; Solar surgery (supplanting surgical lasers with innovations in solarphotonics); Solar innovations for electricity generation with advanced photovoltaic materials;Solar photonics for nanotechnology (new, innovative and affordable methods for synthesizingnanomaterials with concentrated sunlight); Greenhouse temperature control system.Phone: 972-8-659-6927 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. Brown University, USA, 1976; ProfessorAdvanced optical design and radiative transfer (applications in infrared technology, semiconductorprocessing, conventional illumination systems, and the basic understanding of biological visualsystems); Biomedical optics (tailoring fiber-optic light delivery systems for surgical applications);Solar surgery (supplanting surgical lasers with innovations in solar photonics); Solar photonicinnovations for electricity generation with advanced photovoltaic materials; Solar photonics fornanotechnology (synthesis of nanomaterials with innovative ultra-high flux solar concentrators);Physics and engineering of cooling (predictive, diagnostic and optimization methods in chillerscience); Quantum refrigeration theory (molecular cooling and approaching absolute zero);Scientific consultation to Israeli and foreign high-technology industries in optical and thermalengineering.Phone: 972-8-659-6923 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. Ben-Gurion University, 1994; Researcher Grade C.Biomedical optics; Solar energy and nonimaging optics; Finite time thermodynamics; Thermo-dynamics of heat engines and heat pumps; Modeling and numerical analysis of systems.Phone: 972-8-659-6735 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. University of Arizona, 1988; Researcher Grade BRemote sensing; Spatial and spectral data analysis; Application of remote sensing to environmentand earth resources problems; Arid and semiarid regions; Geographic information systems;Digital elevation models; Image processing.Phone: 972-8-659-6855 • Fax: 972-8-659-6704 • E-mail: [email protected]

Ph.D. Moscow Institute of Steel & Alloys, 1990; Researcher Grade BApplied solar energy; Structural defects in semiconductors; Porous silicon; Photovoltaic materials;Silicon solar cells; Fullerenes and fullerene-based solar cells; Carbon nanostructures.Phone: 972-7-659-6739 • Fax: 972-7-659-6736 • E-mail: [email protected]

SERGEY BIRYUKOV

GEORGY I. BURDE

DAVID FAIMAN

DANIEL FEUERMANN

JEFFREY M. GORDON

MAHMUD HULEIHIL

ARNON KARNIELI

EUGENE KATZ


Ph.D. Weizmann Institute of Science, 1986; ProfessorNonlinear dynamics; Pattern formation; Applications to physical, chemical and ecological systems.Phone: 972-8-659-6926 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. University of Bucharest, 1979; Associate ProfessorGeomorphology; Relationships among meteorological parameters, relief morphometry andairborne particles in the Negev desert (as affecting deflation, erosion, transport, sedimentation,composition, aerosols, atmospheric pollution); Practical applications.Phone: 972-8-659-6849 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. Turkmen Institute for Desert Research, USSR, 1987; Researcher Grade BEcological applications of remote sensing; Monitoring of land/vegetation cover changes due todesertification; Salt-dust-raising sources; Dust storm monitoring.Phone: 972-8-659-6857 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. Ben-Gurion University, 1995; Researcher Grade AFree boundary and variational problems; Numerical analysis; Models of dissipative systems;Granular mechanics; Applied superconductivity.Phone: 972-8-659-6922 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. Weizmann Institute of Science, 1978; ProfessorTheory of nonlinear transport processes in continuous media; Mass and momentum transferin electrolyte solutions; Electrochemistry of synthetic ion-exchange membranes (with applicationsto desalination); Semiconductor transport; Chemical engineering.Phone: 972-8-659-6924 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. Novosibirsk State University, Russia, 1989; Senior LecturerIncumbent of the Mendel Wasserman Career Development Chair in Desert StudiesTheory of continuous nonlinear transport processes in heat and mass transfer; Ionic transportin electrolytes and semiconductor transport (including free boundary problems in these systems).Phone: 972-8-659-6928 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. University of California-Los Angeles,1975; Associate ProfessorIncumbent of the Edward and Bertha Rose Chair in Desert MeteorologyDynamic and synoptic meteorology; Synoptic climatology; Rainfall; Relationships between rainfalland the large scale moisture field; Climate change; Connection between climate change andsynoptic mesoscale weather systems.Phone: 972-7-659-6845 • Fax: 972-7-659-6921 • E-mail: [email protected]

Ph.D. Weizmann Institute of Science, 1970; ProfessorIncumbent of the Phyllis and Kurt Kilstock Chair in Environmental Physics of Arid ZonesStochastic aspects of solar research; Nonlinear dynamics; Irreversible thermodynamic analysisof heat and mass transfer processes.Phone: 972-8-659-6920 • Fax: 972-8-659-6921 • E-mail: [email protected]

Ph.D. Weizmann Institute of Science, 1981; Associate ProfessorDynamic optimization methodology and applications; Optimal exploitation of natural resourcesunder uncertainty; R&D investment strategies in environmental projects; Relations betweenecological and economic models.Phone: 972-8-659-6925 • Fax: 972-8-659-6921 • E-mail: [email protected]

EHUD MERON

ZVI Y. OFFER

LEAH ORLOVSKY

LEONID PROGOZHIN

ABRAHAM ZANGVIL

YAIR ZARMI

ISAAK RUBINSTEIN

BORIS ZALTZMAN

AMOS ZEMEL



PUBLICATIONS

Baer, M., A. Hagberg, E. Meron and U. Thiele. Front dynamics in catalytic surface reactions. Catalysis Today 70:331-340 (2001)Brenig, L. and Z.Y. Offer. Airborne particle dynamics: Towards a theoretical approach. Environmental Modeling and Assessment 1:1-5 (2001)Brenig, L., Z.Y. Offer and I. Mahrer. Artificial weather modification by ground solar absorbing surface. Applied Solar Energy 37:38-48 (2001)Burde, G.I. Potential symmetries of the nonlinear wave equation utt = (uux)x and related exact and approximate solutions.

Journal of Physics A: Mathematical and General 34:5355-5371 (2001)Burde, G.I. and A. Zangvil. The estimation of regional precipitation recycling. Part I: Review of recycling models.

Journal of Climate 14:2497-2508 (2001)Burde, G.I. and A. Zangvil. The estimation of regional precipitation recycling. Part II: A new recycling models.

Journal of Climate 14:2509-2527 (2001)Faiman, D., H. Hazan and I. Laufer. Reducing the heat loss at night from solar water heaters of the integrated collector-storage variety.

Solar Energy 71:87-93 (2001)Fedotov, A., A. Mazanik and E.A. Katz. Modification of electrical activity of grain boundaries in EFG silicon under influence of hydrogen plasma.

Interface Science 9:169-173 (2001)Feuermann, D. and J.M. Gordon. Gradient-index rods as flux concentrators with applications to laser fiber-optic surgery.

Optical Engineering 40:418-425 (2001)Feuermann, D. and J.M. Gordon. High-concentration photovoltaic designs based on miniature parabolic dishes. Solar Energy 70:423-430 (2001)Formenti, P., M.O. Andreae, T.W. Andreae, E. Galani, A. Vasaras, C. Zerefos, V. Amiridis, L. Orlovsky, A. Karnieli, M. Wendish, H. Wex, B.N. Holben,

W. Maenhaut and J. Lelieveld. Aerosol optical properties and large-scale transport of air masses: Observations at a coastal and a semiaridsite in the eastern Mediterranean during summer 1998. Journal of Geophysical Research 106:9807-9826 (2001)

Formenti, P., M.O. Andreae, T.W. Andreae, C. Ichoku, G. Schebeske, A.J. Kettle, W. Maenhaut, J. Cafmeyer, J. Ptasinsky, A. Karnieli and J. Lelieveld.Physical and chemical characteristics of aerosols over the Negev Desert (Israel) during summer 1996.Journal of Geophysical Research 106:4871-4890 (2001)

Garty, J., O. Tamir, I. Hassid, A. Eshel, Y. Cohen, A. Karnieli and L. Orlovsky. Photosynthesis, chlorophyll integrity and spectral reflectance in lichensexposed to air pollution. Journal of Environmental Quality 30:884-893 (2001)

Garty, J., L. Weissman, Y. Cohen, A. Karnieli and L. Orlovsky. Transplanted lichens in and around the Mount Carmel National Park and the HaifaBay industrial region in Israel: Physiological and chemical responses. Environmental Research 85:159-176 (2001)

Gordon, J.M., Editor. Solar Energy – the State of the Art, James and James Science Publishers, London, UK, pp. 720 (2001)Holben, B.N., D. Tanré, A. Smirnov, T.F. Eck, I. Slutsker, B. Chatenet, F. Lavenue, Y.J. Kaufman, J. Van de Castle, A. Setzer, B. Markham, M. Clark,

R. Frouin, A. Karnieli, N. O’Neill, C. Pietras, R. Pinker, K. Voss and G. Zibordi. An emerging ground-based aerosol climatology: AerosolOptical Depth from AERONET. Journal of Geophysical Research 106:12,067-12,097 (2001)

Karnieli, A. and J. Cierniewski. Inferring roughness of desert rocky surfaces from their bidirectional reflectance data.Advances in Space Research 28:171-176 (2001)

Karnieli, A., Y.J. Kaufman, L.A. Remer and A. Ward. AFRI – Aerosol free vegetation index. Remote Sensing of Environment 77:10-21 (2001)Karnieli, A., R.F. Kokaly, N.E. West and R.N. Clark. Remote sensing of biological soil crusts. In: Biological Soil Crusts: Structure, Function and

Management (Eds. J. Belnap and O. Lange), Springer-Verlag, Berlin, pp. 431-455 (2001)Katz, E.A., D. Faiman, S. Shtutina, N. Froumin, M. Polak, A.P. Isakina, K.A. Yagotintsev, M.A. Strzhemechny, Y.M. Strzhemechny, V.V. Zaitsev

and S.A. Schwarz. Structural and chemical modifications in Cu-supported C60 thin films exposed to an atmosphere of air or iodine.Physica B 304:348-356 (2001)

Katz, E.A., D. Faiman, S. Shtutina, A. Isakina, K. Yagotintsev and K. Iakoubovskii. High quality textured C60 thin films on a mica substrate: Growth,crystalline structure, electrical and photoelectrical properties. Solid State Phenomena 80-81:15-20 (2001)

Katz, E.A., D. Faiman, S.M. Tuladhar, J.M. Kroon, M.M. Wienk, T. Fromherz, F. Padinger, C.J. Brabec and N.S. Sariciftci. Temperature dependencefor the photovoltaic device parameters of polymer-fullerene solar cells under operating conditions.Journal of Applied Physics 90:5343-5350 (2001)

Katz, E.A., S.M. Tuladhar, D. Faiman, A.I. Shames and S. Shtutina. Grain boundary diffusion in C60 thin films. Interface Science 9:331-335 (2001)Kaufman, Y.J., D. Tanré, O. Dubovik, A. Karnieli and L.A. Remer. Satellite and ground-based remote sensing of dust absorption of sunlight.

Geophysical Research Letters 28:1479-1482 (2001)Manspeizer, N., A. Karnieli, Y. Arkin and J. Chorowicz. Analyzing potential cliff erosivity from ERS-SAR satellite imagery.

International Journal of Remote Sensing 22:807-817 (2001)Offer, Z.Y. and D. Goossens. Airborne particle accumulation and composition at different locations in the northern Negev desert.

Annals of Geomorphology 45:101-120 (2001)Offer, Z.Y. and D. Goossens. Ten years of Aeolian dust dynamics in a desert region (Negev desert, Israel): Analysis of airborne dust concentration,

dust accumulation and the high-magnitude dust events. Journal of Arid Environments 47:211-249 (2001)Orlovsky, L. and A. Karnieli. Effect of biogenic crusts on spectral properties of the landscapes along Negev-Sinai border.

Arid Ecosystems 7:22-30 (2001)Orlovsky, N., V. Radzinsky and L. Orlovsky. Desertification and population health in the Turkmenistan part of the Aral Sea region. In: Environmental

Health Risk (Eds. C.A. Brebbia and D. Fayzieva), WIT Press, Southampton, Boston, pp. 267-276 (2001)


Palao, J.P., R. Kosloff and J.M. Gordon. Quantum thermodynamic cooling cycle. Physical Review E 64:056130, 8 pp. (2001)Prigozhin, L. and B. Zaltzman. Two continuous models for the dynamics of sandpile surfaces. Physical Review E 63:041505, 6 pp. (2001)Qin, Z., G. Dall’Olmo, A. Karnieli and P. Berliner. Derivation of split window algorithm and its sensitivity analysis for retrieving land surface

temperature from NOAA-AVHRR data. Journal of Geophysical Research 106:655-670 (2001)Qin, Z., A. Karnieli and P. Berliner. Thermal variation in the Israel-Sinai (Egypt) peninsula region. International Journal of Remote Sensing

22:915-919 (2001)Qin, Z., A. Karnieli and P. Berliner. A mono-window algorithm for retrieving land surface temperature from Landsat TM6 data and its

application to the Israel-Egypt border region. International Journal of Remote Sensing 22:3719-3746 (2001)Qin, Z., Z. Ming-Hua, A. Karnieli and P. Berliner. Mono-window algorithm for retrieving land surface temperature from Landsat TM6 data (in Chinese

with English abstract). ACTA Geographica Sinica 56:456-466 (2001)Rubinstein, I., J. Pretz and E. Staude. Open circuit voltage in a reverse electrodialysis cell. Physical Chemistry Chemical Physics 3:1666-1667 (2001)Rubinstein, I. and B. Zaltzman. Electro-osmotic slip of the second kind and instability in concentration polarization at electrodialysis membranes.

Mathematical Models and Methods in Applied Science 11:263-300 (2001)Schmidt, H. and A. Karnieli. Sensitivity of vegetation indices to substrate brightness in hyper-arid environment: The Makhtesh Ramon Crater (Israel)

case study. International Journal of Remote Sensing 22:3503-3520 (2001)Tanré, D., Y.J. Kaufman, B.H. Holben, B. Chatenet, A. Karnieli, F. Lavenu, L. Blarel, O. Dubovik, L.A. Remer and A. Smirnov. Climatology of dust

aerosol size distribution and optical properties derived from remotely sensed data in the solar spectrum.Journal of Geophysical Research – Atmosphere 106:18,205-18,217 (2001)

Tsur, Y. and A. Zemel. The infinite horizon dynamic optimization problem revisited: A simple method to determine equilibrium states.European Journal of Operational Research 131:482-490 (2001)

Von Hardenberg, J., E. Meron, M. Shachak and Y. Zarmi. Diversity of vegetation patterns and desertification.Physical Review Letters 87:198101, 5 pp. (2001)

Zaady, E., Z.Y. Offer and M. Shachak. The content and the contribution of the accumulated aeolian organic matter in a dry land ecosystem.Atmospheric Environment 35:769-776 (2001)

Zemel, A., I. David and A. Mehrez. On conducting simultaneous vs. sequential engineering activities in risky R&D.International Transactions in Operational Research 8:585-601 (2001)

Zangvil, A., D.H. Portis and P.J. Lamb. Investigation of the large-scale atmospheric moisture field over the Midwestern United States in relation tosummer precipitation. Part I: Relationship between moisture budget components on different time scales.Journal of Climate 14:582-597 (2001)

Parabolic reflectors used by the PATROL laboratory to test systems that could produce heat for industry

DEPARTMENT OF SOLAR ENERGY AND ENVIRONMENTAL PHYSICS

Dov BokovzaSvetlana Gillerman (deceased 2001)Alexander GoldbergShlomo KabaloDavid KlepachBryan MedwedVladimir MelnichekNatalia PanovBoris Zabejinsky

Mazal AdarShoshana DannLilian Na’aman

Dr. Aric Hagberg – Los Alamos National Laboratory, USA.Dr. Takashi Nakamura – Physical Sciences Inc., San Francisco, CA, USA.Dr. Harold Ries – Optics and Energy Concepts, Munich, GermanyDr. Vladimir Zidek

Dr. Jie Chen, ChinaDr. Jost von Hardenberg, Torino, Italy.

Shay Ben DavidAyal Ben-ZeevJonathan BurgheimerGandush ChantuuYvgeni DerimianDavid FiguerasRimma GlukhihKadmiel MaseykTamara PundikPabitra ShakyaMichal RazAdi ShalevSachetan Man TuledharAlex VekslerAnat VolcaniRongrong YangHezi YizhaqArik YochelisBayarjargal YuSergey ZinevichHagit ZioniYosi Zvieli

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