Pultruded fibre reinforced polyurethane composites II. Effect of processing parameters on mechanical and thermal properties

This paper presents a novel process for the fabrication of pultruded polyurethane (PU) composites. The effects of the processing parameters on the mechanical properties (flexural strength and flexural modulus, etc.) and thermal properties (HDT) of the fibre reinforced PU composites by pultrusion have been studied. The processing parameters investigated include pulling rate (in-line speed), die temperature, filler type and content, and post-cure time and temperature. Results show that the composites possessed various optimum pulling rates at different die temperatures. On the basis of the DSC diagram, the swelling ratio, the mechanical properties and the thermal properties of composites, the optimum die temperature can be determined. It is found that the mechanical and thermal properties increase with filler content for various types of filler. The mechanical and thermal properties increase at a suitable post-cure temperature and time. Furthermore, the properties which decreased due to the degradation of composite materials for a long post-cure time will be discussed.     

环境放射化学研究中几个问题的讨论

本文从辐射环境保护和公众辐射防护的角度，讨论了放射性核素在环境中的迁移行为，放射性核素与环境介质的相互作用和放射性核素在环境中的形态等涉及到环境放射化学研究方向的问题，并讨论了它们之间相互依存的关系。     

Group decision support system for assessment of problem-basedlearning

Assessment is an important task in problem-based learning (PBL). It has a strong influence on students' approaches to learning and their outcomes. In order to provide an open and fair method of PBL assessment, a group decision support system (GDSS) has been developed. The system uses mathematical decision methods for collecting assessment criteria and their appropriate weights, and databases for storing students' details and data on the assessment criteria. It integrates databases with model bases in a cooperative decision-making environment and is implemented on a client-server platform using a relational database management system. The GDSS has been developed and used to improve the efficiency and quality of assessing students' PBL outcomes     

金刚石光电导探测器研制及在软X光测量中的初步应用

介绍了我们自己设计制造的天然Ⅱａ型金刚石光导探测器的结构，原理，制造工艺，实验标定及其在ＩＣＦ实验中软Ｘ光测量中的应用等。     

双能X射线骨密度仪测定技术研究

以Ｌｕｎａｒ公司ＤＰＸ－Ｌ型双能Ｘ射线骨密度仪为例，研究引起测量误差的主要因素并提出质控措施。用自检模块、腰椎体膜评定仪器的体外测量精度好于１％。对１０位志愿者重复２次测量，体内精度对腰椎，ＭＰＤ（平均百分差）为０．４６，ＣＶ（变异系数）为０．７５；对股骨颈，ＭＰＤ为１．２６、ＣＶ为０．４７；Ｗａｒｄ’ｓ三角区ＭＰＤ为２．０１、ＣＶ为１．１４；大转子ＭＰＤ为１．６６、ＣＶ为０．７２。扫描图像由２位     

Automatically modeling, simulating and explaining physical systems

This paper presents an interactive framework for constructing models from high-level specifications of real physical systems, deriving low-level simulations from the constructed models and then generating explanations of the simulated behavior to help engineers interpret and control the real physical systems. To demonstrate our method, we show an example of modeling river networks, which are eco-environmental engineering systems, to provide a computer-based solution to problems of simulating and controlling concentrations of water quality constituents in river networks[1].     

A frequency-aware and energy-saving strategy based on DVFS for Spark

The Journal of Supercomputing - With the fast growth of big data applications, it has brought about a huge increase in the energy consumption for big data processing in Cloud data centers. In this...     

A central crack of mode III in a rectangular sheet with fixed edges

This paper discusses the general solution, by use of the Fourier transform and Fourier series, of the stress intensity factor in a rectangular sheet containing a central crack of mode III, where its boundary is constrained, but its crack surface is subjected to an arbitrary anti-plane load. As examples of numerical computing, consider three circumstances: (1) the boundary parallel to a central crack is fixed; (2) the boundary perpendicular to a central crack is fixed; (3) all of the boundaries around a central crack are fixed but the crack surface is subjected to a constant load.En faisant appel à une transformation de Fourier et aux séries de Fourier, on discute dans cet article de la solution générale au facteur d'intensité de contraintes existant dans une tôle rectangulaire comportant une fissure centrale de mode III, lorsque les bords sont fixés mais que la surface de la fissure est soumise à une charge antiplanaire arbitraire. Comme exemple de calcul numérique, on envisage trois cas distincts:

基于互联网实现多种信息传输技术

随着信息技术的迅速发展,使用互联网实现楼宇内电话、电视、电脑、安防和环境监控、计量数据等信息的合路传输,是实现智能家居和数字楼宇的一种主要发展趋势。最终目的,实现对物和过程的智能化感知。文章首先介绍信息合路编码、中央控管电路,然后介绍网络接口电路原理和系统体系构架。重点介绍多种多样的信息传输技术。它对现代楼宇信息化、智能化建设有很好的参考作用。     

A fonnalism for generating multiparametric encoding gradients in NMR tomography

A general mathematical formalism for generating multiparametric NMR image encoding gradients is introduced. The new schematic approach enables one to construct any desired encoding gradient which may be used in an imaging sequence. Basic gradient waveforms which can be used as building blocks of the desired encoding gradients are presented. A matrix operator for obtaining the encoding gradient for any kind of phase encoding is derived. Specific examples illustrating how to obtain "pure" spatial, velocity, or acceleration encoding gradients for moving spins are presented.