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

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

A programming logic for Java bytecode programs

One significant disadvantage of interpreted bytecode languages, such as Java, is their low execution speed in comparison to compiled languages like C. The mobile nature of bytecode adds to the problem, as many checks are necessary to ensure that downloaded code from untrusted sources is rendered as safe as possible. But there do exist ways of speeding up such systems. One approach is to carry out static type checking at load time, as in the case of the Java Bytecode Verifier. This reduces the number of runtime checks that must be done and also allows certain instructions to be replaced by faster versions. Another approach is the use of a Just In Time (JIT) Compiler, which takes the bytecode and produces corresponding native code at runtime. Some JIT compilers also carry out some code optimization. There are, however, limits to the amount of optimization that can safely be done by the Verifier and JITs; some operations simply cannot be carried out safely without a certain amount of runtime checking. But what if it were possible to prove that the conditions the runtime checks guard against would never arise in a particular piece of code? In this case it might well be possible to dispense with these checks altogether, allowing optimizations not feasible at present. In addition to this, because of time constraints, current JIT compilers tend to produce acceptable code as quickly as possible, rather than producing the best code possible. By removing the burden of analysis from them it may be possible to change this. We demonstrate that it is possible to define a programming logic for bytecode programs that allows the proof of bytecode programs containing loops. The instructions available to use in the programs are currently limited, but the basis is in place to extend these. The development of this logic is non-trivial and addresses several difficult problems engendered by the unstructured nature of bytecode programs

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

Evaluating complications in below-knee skin cancer surgery after introduction of preoperative appointments : A 2-year retrospective cohort study

Below-knee dermatological surgery has a high risk of complications such as wound infection, bleeding, and necrosis. In this study, we evaluated the impact of preoperative appointments on complication risks. We searched the medical records of the Helsinki University Central Hospital (HUS) Dermatosurgery unit for all below-knee surgeries during 2016, when no preoperative nurse appointments were carried out, and compared it with 2018, when preoperative appointments for risk patients were introduced. The study included 187 patients in 2016 and 179 patients in 2018, of whom 68 (about one third) attended preoperative appointments. At the appointments, risk factors were evaluated, and compression therapy was introduced when possible. The results show complication rates of 13.4% in 2016 vs 10.1% in 2018 (P = .33), despite significantly higher risks in the 2018 patient group. The odds ratio for complications in appointment attendees vs non-attendees was reduced after adjustments to 0.58; however, this was insignificant (P = .47). The odds of complications for skin grafts were considerably higher: 11.33 vs other surgery techniques (P = .00). In conclusion, the introduction of preoperative appointments appeared to reduce complications in below-knee surgery. For graft reconstructions, complication risk is high, even with carefully planned pre- and postoperative care. Further studies are needed to evaluate preventable risk factors of below-knee graft reconstructions.Peer reviewe

Robotin tarttujavaihtoehdot

Tiivistelmä. Tässä kandidaatin työssä keskitytään pääasiassa teollisuudessa nyt käytettäviin ja mahdollisesti tulevaisuudessa käyttöön otettaviin tarttujiin. Robotit sekä niissä käytettävät tarttujat ovat kehittyneet viime vuosikymmeninä erittäin paljon. Tämä on mahdollistanut robottien käytön yleistymisen myös sellaisilla teollisuuden aloilla, joissa sen joskus uskotiin olevan mahdotonta. Työ aloitetaan perehtymällä robottien ja tarttujien historiaan. Lisäksi työssä esitellään erilaisia tarttujatyyppejä sekä malleja perinteisistä kaksisormisista tarttujista uusimpiin innovaatioihin pehmeiden robottitarttujien muodossa. Lopuksi pohditaan mitä tarttujan valinnassa tulee ottaa huomioon.Robot gripper options. Abstract. This bachelor’s thesis mainly focuses on grippers used in industrial robots. Robots and the grippers have evolved a lot over the last few decades. This has allowed the use of robots to become more common in industries where it was believed to be impossible before. The thesis is started by presenting a brief history of robots and grippers. In addition, this work introduces different types of grippers and models from traditional 2-finger gripper to the latest innovations especially in soft robotics. Finally, the work focuses on what you must consider when choosing the gripper for specific job

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

Systemic inflammatory responses following welding inhalation challenge test

Peer reviewe