Heavy doping effects in high efficiency silicon solar cells

A model for bandgap shrinkage in semiconductors is developed and applied to silicon. A survey of earlier experiments, and of new ones, give an agreement between the model and experiments on n- and p-type silicon which is good as far as transport measurements in the 300 K range. The discrepancies between theory and experiment are no worse than the discrepancies between the experimental results of various authors. It also gives a good account of recent, optical determinations of band gap shrinkage at 5 K

Tiltaksplan for forurensede sedimenter i Aust-Agder. Fase 1 - Miljøtilstand,

Rapporten omhandler første fase av tiltaksplan for forurensede sedimenter i Aust-Agder. De tre utvalgte områdene i Aust-Agder er Tvedestrand på innsiden av Sagesund, Arendal havneområde med Tromøysund og Vikkilen i Grimstad. I dette arbeidet er det gjort en gjennomgang av eksisterende data med kartpresentasjon av miljøstatus for de ulike miljøgiftene i hvert tiltaksområde. Videre er det gitt en oversikt over aktuelle og mulige kilder til forurensning i nedbørfeltet og høyrisikoområder er foreslått. Data fra indre Tvedestrandsfjord har vist høye konsentrasjoner av både PAH og TBT (tilstandsklasse IV-V) slik at flere grunne områder er definert som mulige høyrisikoområder. Det er imidlertid behov for å ta prøver i grunne farvann for å kunne fastslå dette. I Arendal er spesielt havneområdene og området rundt Eydehavn forurenset av miljøgifter, men også småbåthavner og andre områder er sterkt forurenset. I likhet med Tvedestrand er det også her lite data fra grunne områder som er mest utsatt for spredning. Indre del av Vikkilen er foreslått som høyrisikoområde på grunn av høye PAH-verdier og ekstremt høye TBT-verdier. Det er behov for å ta prøver som verifiserer nivåene og gir opplysning om omfang

Constitutive modeling for isotropic materials (HOST)

The results of the third year of work on a program which is part of the NASA Hot Section Technology program (HOST) are presented. The goals of this program are: (1) the development of unified constitutive models for rate dependent isotropic materials; and (2) the demonstration of the use of unified models in structural analyses of hot section components of gas turbine engines. The unified models selected for development and evaluation are those of Bodner-Partom and of Walker. A test procedure was developed for assisting the generation of a data base for the Bodner-Partom model using a relatively small number of specimens. This test procedure involved performing a tensile test at a temperature of interest that involves a succession of strain-rate changes. The results for B1900+Hf indicate that material constants related to hardening and thermal recovery can be obtained on the basis of such a procedure. Strain aging, thermal recovery, and unexpected material variations, however, preluded an accurate determination of the strain-rate sensitivity parameter is this exercise. The effects of casting grain size on the constitutive behavior of B1900+Hf were studied and no particular grain size effect was observed. A systematic procedure was also developed for determining the material constants in the Bodner-Partom model. Both the new test procedure and the method for determining material constants were applied to the alternate material, Mar-M247 . Test data including tensile, creep, cyclic and nonproportional biaxial (tension/torsion) loading were collected. Good correlations were obtained between the Bodner-Partom model and experiments. A literature survey was conducted to assess the effects of thermal history on the constitutive behavior of metals. Thermal history effects are expected to be present at temperature regimes where strain aging and change of microstructure are important. Possible modifications to the Bodner-Partom model to account for these effects are outlined. The use of a unified constitutive model for hot section component analyses was demonstrated by applying the Walker model and the MARC finite-element code to a B1900+Hf airfoil problem

Three Styles in the Study of Violence

This is a postprint (accepted manuscript) version of the article published in Reviews in Anthropology 37:1-19. The final version of the article can be found at http://dx.doi.org/10.1080/00938150701829525 (login required to access content). The version made available in Digital Common was supplied by the author.Accepted Manuscripttru

Actors that Unify Threads and Events

There is an impedance mismatch between message-passing concurrency and virtual machines, such as the JVM. VMs usually map their threads to heavyweight OS processes. Without a lightweight process abstraction, users are often forced to write parts of concurrent applications in an event-driven style which obscures control flow, and increases the burden on the programmer. In this paper we show how thread-based and event-based programming can be unified under a single actor abstraction. Using advanced abstraction mechanisms of the Scala programming language, we implemented our approach on unmodified JVMs. Our programming model integrates well with the threading model of the underlying VM

Experimental investigation of the excess charge and time constant of minority carriers in the thin diffused layer of 0.1 ohm-cm silicon solar cells

An experimental method is presented that can be used to interpret the relative roles of bandgap narrowing and recombination processes in the diffused layer. This method involves measuring the device time constant by open-circuit voltage decay and the base region diffusion length by X-ray excitation. A unique illuminated diode method is used to obtain the diode saturation current. These data are interpreted using a simple model to determine individually the minority carrier lifetime and the excess charge. These parameters are then used to infer the relative importance of bandgap narrowing and recombination processes in the diffused layer

On bulk singularities in the random normal matrix model

We extend the method of rescaled Ward identities of Ameur-Kang-Makarov to study the distribution of eigenvalues close to a bulk singularity, i.e. a point in the interior of the droplet where the density of the classical equilibrium measure vanishes. We prove results to the effect that a certain "dominant part" of the Taylor expansion determines the microscopic properties near a bulk singularity. A description of the distribution is given in terms of a special entire function, which depends on the nature of the singularity (a Mittag-Leffler function in the case of a rotationally symmetric singularity).Comment: This version clarifies on the proof of Theorem

The time to extinction for an SIS-household-epidemic model

We analyse a stochastic SIS epidemic amongst a finite population partitioned into households. Since the population is finite, the epidemic will eventually go extinct, i.e., have no more infectives in the population. We study the effects of population size and within household transmission upon the time to extinction. This is done through two approximations. The first approximation is suitable for all levels of within household transmission and is based upon an Ornstein-Uhlenbeck process approximation for the diseases fluctuations about an endemic level relying on a large population. The second approximation is suitable for high levels of within household transmission and approximates the number of infectious households by a simple homogeneously mixing SIS model with the households replaced by individuals. The analysis, supported by a simulation study, shows that the mean time to extinction is minimized by moderate levels of within household transmission

Application-Driven Customization of an Embedded Java Virtual Machine

Java for embedded devices is today synonym of "embeddable pseudo-Java". In order to limit their memory footprint, the embedded flavors of Java introduce incompatibilities against the standard edition, and break Java's portability rule. The application developer has to comply to specific Java APIs and incomplete runtime features. In this paper, we introduce a way to embed applications written for Java 2 Standard Edition. The applications are pre-deployed into a virtual Java execution environment, which is analyzed so that the Java virtual machine can be tailored according to the runtime needs of the system. Thus, the programmer is not enforced to comply to a particular Java environment; but conversely, the Java environment is customized according to its applications and targeted device. Experiments reveal that the customized virtual machines are comparable in size to existing static embedded Java solutions, while being more flexible and preserving Java compatibility

Sawja: Static Analysis Workshop for Java

Static analysis is a powerful technique for automatic verification of programs but raises major engineering challenges when developing a full-fledged analyzer for a realistic language such as Java. This paper describes the Sawja library: a static analysis framework fully compliant with Java 6 which provides OCaml modules for efficiently manipulating Java bytecode programs. We present the main features of the library, including (i) efficient functional data-structures for representing program with implicit sharing and lazy parsing, (ii) an intermediate stack-less representation, and (iii) fast computation and manipulation of complete programs