Evaluation of an improved hybrid six-flux/zone model for radiative transfer in rectangular enclosures

An improved model for the calculation of radiative transfer in enclosures filled with an absorbing, emitting and scattering medium is presented. The model is denoted by a hybrid six-flux/zone model since it combines features of both the zone method and (three-dimensional) six-flux models. Compared to the zone method, computation time is considerably reduced and reaches approximately the same order as the faster flux-type models. The accuracy of the hybrid six-flux/zone model presented here is drastically improved without increasing computation time. This is achieved by introducing a correction for the directional characteristics of the propagation of radiation through adjacent zones. The thus improved hybrid model is evaluated for a realistic recognized test problem and found to be an efficient and accurate tool for calculating radiative transfer in enclosures filled with a participating medium.     

可溶高分子负载钯催化剂对于硝基苯加氢反应催化性能的研究

以醇或水溶性高分子（聚乙烯吡咯烷酮，ＰＶＰ；乙基纤维素，ＥＣ；聚乙烯醇，ＰＶＡ；羧甲基纤维素钠，ＣＭＣＮａ）为载体，制备了四种可溶高分子负载钯催化剂。无机碱的存在对反应呈明显的加速效应。在少量Ｋ２ＣＯ３存在下，ＥＣ－ＰｄＣｌ２和ＰＶＰ－ＰｄＣｌ２对于硝基苯的催化加氢具有非常高的活性，最高活性＞２３０ｍｏｌＨ２／ｍｏｌＰｄ·ｍｉｎ，即大于５１５０ｍｌＨ２／ｍｍｏｌＰｄ·ｍｉｎ，该数值是已知文献报道的最好结果。详细考察了各种碱、Ｋ２ＣＯ３用量、溶剂以及反应温度对ＰＶＰ－ＰｄＣｌ２催化硝基苯加氢性能的影响。     

Gobang ist PSPACE-vollständig

Summary For many games, the decision problem of whether a player in a given situation has a winning strategy has been shown to be PSPACE-complete. Following the PSPACE-completeness results of Even and Tarjan [1] for generalized Hex on graphs and of Schaefer [6] for a variety of combinatorial games, the decision problems were shown to be PSPACE-hard for generalizations of Go and Checkers. In this paper a corresponding theorem is proved for the board-game Gobang, a variant of Go. Since the decision problem for Gobang states-of-play itself lies in PSPACE, it can be shown that Gobang is in fact PSPACE-complete.     

基坑支护优化设计的数学模型研究

基坑支护设计属于系统工程设计,包括方案设计和细部结构设计两个层次,相应地,基坑支护设计变量具有层次性、结构性和不确定性．对此,提出了基于搜索的基坑支护协同优化设计分析模型,给出了与方案、细部和子细部优化相对应的数学模型,并讨论了总系统优化与各子系统优化即全局寻优与局部寻优的关系,得出“必须求解能全面反映各子系统间各种耦合关系的总系统才能得到基坑支护系统的全局最优解”的结论。     

Benzoic Acid Derivatives in a Hypogastrurid Collembolan: Temperature-Dependent Formation and Biological Significance as Deterrents

Two phenolic acids were identified in the collembolan Ceratophysella denticulata: 3-hydroxy-4,5 dimethoxy benzoic acid and 4-hydroxy-3,5-dimethoxybenzoic acid (syringic acid). These are localized on or in the integument of the springtail, in field-collected animals, in a ratio of 47:100 (v/v). Springtails kept under different temperature regimes showed differences in production and ratio of the benzoic acid derivatives. At 20 degrees C, C. denticulata produced only syringic acid, whereas at 10 degrees C both isomers in a ratio of 100:61 (v/v) were detected. Bioassays with C. denticulata as well as with the specialized collembolan predator Stenus comma (Staphylinidae) were carried out. Staphylinid beetles topically treated with the acids try to clean their mouthparts by rubbing them on the ground significantly more often than do control beetles. Both compounds individually and as a natural mixture have deterrent effects towards the predator S. comma.     

Synthesis of new boron-rich building blocks for boron neutron capture therapy or energy-filtering transmission electron microscopy

The synthesis of a new ortho-carborane derivative, tetracarboranylketone 4, is reported here. Ketone 4 was prepared from a tetraalkynylated ketone by the addition of decaborane. The keto group was then easily modified to yield the glycosides 17alpha and 18beta, which contain glucose or galactose, respectively, and the nucleotide 13b. In addition to ketone 4, which is acyclic, cyclic ketone 8 was also synthesised. X-ray diffraction analysis of compound 4 indicated the presence of two toluene guest molecules per molecule of the host compound. Furthermore, compound 4 displays a rather low cytotoxicity. These novel products can be used as building blocks to create a new class of biomolecules containing high-density carborane clusters. Such molecules may constitute powerful tools for applications like Boron Neutron Capture Therapy or Energy-Filtering Transmission Electron Microscopy.     

Severe accidents in the energy sector: comparative perspective

This paper addresses one of the controversial issues in the current comparative studies of the environmental and health impacts of energy systems, i.e. the treatment of severe accidents. The work covers technical aspects of severe accidents and thus primarily reflects an engineering perspective on the energy-related risk issues, though some social implications are also touched upon. The assessment concerns fossil energy sources (coal, oil and gas), nuclear power and hydro power. The scope is not limited to the power production (conversion) step of these energy chains but, whenever applicable, also includes exploration, extraction, transports, processing, storage and waste disposal. With the exception of the nuclear chain the focus of the work has been on the evaluation of the historical experience of accidents. The basis used for this evaluation is a comprehensive database ENSAD (Energy-related Severe Accident Database), established by the Paul Scherrer Institut (PSI). For hypothetical nuclear accidents the probabilistic technique has also been employed and extended to cover the assessment of economic consequences of such accidents. The broader picture obtained by coverage of full energy chains leads on the world-wide basis to aggregated immediate fatality rates being much higher for the fossil chains than what one would expect if only power plants were considered. Generally, the immediate fatality rates are for all considered energy carriers significantly higher for the non-OECD countries than for OECD countries. In the case of hydro and nuclear the difference is in fact dramatic. The presentation of results is not limited to the aggregated values specific for each energy chain. Also frequency-consequence curves are provided. They reflect implicitly the ranking based on the aggregated values but include also such information as the observed or predicted chain-specific maximum extents of damages. This perspective on severe accidents may lead to different system rankings, depending on the individual risk aversion.     

Assessment of elastic parameters of human skin using dynamic elastography

Sonoelastography and transient elastography are two ultrasound-based techniques that facilitate noninvasive characterization of the viscoelastic properties of soft tissues by investigating their response to shear mechanical excitation. Young's modulus is the principle assessment parameter. Because it defines local tissue stiffness, it is of major interest for the medical imaging and cosmetic industries as it could replace subjective palpation by yielding local, quantitative information. In this paper, we describe a new high-resolution device capable of measuring local Young's modulus in very thin layers (1-5 mm) and devoted to the in vivo evaluation of the elastic properties of human skin. It uses an ultrasonic probe (50 MHz) for tracking the displacements induced by a 300 Hz shear wave generated by a ring surrounding the transducer. The displacements are measured using a conventional cross-correlation technique between successive ultrasonic back-scattered echoes. First, this noninvasive technique has been experimentally proven to be accurate for investigating elasticity in different skin-mimicking phantoms. Second, data were acquired in vivo on human forearms. As expected, Young's modulus was found to be higher in the dermis than in the hypodermis and other soft tissues.