采用高分辨率高精度格式求解跨音压气机转子内三维粘性流场

采用一种新型的ＬＵ隐式算法及４－５阶高分辨率ＴＶＤ格式求解了叶轮机械内的三维Ｎ－Ｓ方程和ｑ－ｗ湍流模型。应用几何法与ＰＤＦ方法混合的网格生成程序,得到了ＲＯＴＲＯ３７跨音速压气机转子内的Ｈ型网格,并将数值模拟的结果同ＬＤＶ实验值进行了比较。     

透平级非设计工况气动性能的数值模拟

采用新型 ＬＵ隐式格式和改良型高阶 ＭＵＳＣＬ ＴＶＤ格式求解全三维雷诺平均的 Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程和 ｑ－ｗ低雷诺数双方程湍流模型,对一台ＮＡＳＡ跨音单级透平在不同工况下的内部流场进行了详细的数值模拟,并与可能得到的实验结果进行了对比。总结了小流量工况下动叶内部流动的分离模式。     

用多块多网格方法数值模拟三维粘性流动

本文给出了一个模拟三维粘性流动的数值方法．该方法来用高分辨率 ＴＶＤ Ｌａｘ－Ｗｅｎｄｒｏｆｆ格式求解三维雷诺平均Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程，使用Ｂａｌｄｗｉｎ－Ｌｏｍａｘ模型估计湍流粘性系数，用多重网格技术加速收敛，采用多块结构化网格处理复杂的物理域．文中给出了叶轮机械多个叶片排和透平排汽缸内的全三维粘性流动的数值结果．     

迎风型TVD格式在高速进气道粘性流动模拟中的应用

迎风型ＴＶＤ格式在高速进气道粘性流动模拟中的应用刘晶昌，徐建中（中国科学院工程热物理研究所北京１０００８０）邢君波（航天部３１所北京１０００８０）关键词超音速进气道，数值模拟，Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程１前言高速进气道流动做为一种非常复杂的流动，...     

叶栅内定常及非定常粘性流动数值模拟

本文给出了一个模拟叶栅内准三维定常和非定常粘性流动的数值方法。对于定常流动,采用ＴＶＤ Ｌａｘ－Ｗｅｎｄｒｏｆｆ格式和代数湍流模型求解雷诺平均Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程,使用当地时间步长和多网格技术使计算加速收敛到定常状态;对于非定常流动,使用双时间步长和全隐式离散,采用与求解定常流动相似的多网格方法求解隐式离散方程。文中给出了ＶＫＩ透平叶栅内的定常流结果和１．５级透平叶栅内的非定常数值结果。     

氙灯泵浦新型晶体Nd∶S－VAP调Q激光器腔内倍频研究

采用氙灯泵浦晶体Ｎｄ∶Ｓ－ＶＡＰ，ＫＴＰ晶体腔内倍频，实现了Ｎｄ∶Ｓ－ＶＡＰ晶体０．５３２５μｍ绿光激光ＢＤＮ染料片调Ｑ运转。测量了输出绿光激光的特性及不同腔长和染料片小信号透过率情况下的输出能量及脉冲宽度，给出了染料片调Ｑ腔内倍频的耦合波方程组，数值求解方程组，所得的理论数据与实验结果很好地相符     

用有限元方法求解双曲守恒律

分片线性插值有限元给出了求解双曲守恒律的计算方法。有别于不连续有限元方法求解双曲守恒律在相邻单元边界上求Ｒｉｅｍａｎｎ解,利用双曲守恒律的Ｈａｍｉｌｔｏｎ－Ｊａｃｏｂｉ方程形式,直接应用有限元求解,在ＣＦＬ下,证明了计算格式满足极大值原理,并且是ＴＶＤ格式。数值例子在文后给出。此外,方法推广到流体力学方程组和高维问题,将在另文中邓以讨论。     

用STC格式求解二维激波─边界层相互作用问题

将空间－时间守恒（ＳＴＣ）格式应用于求解Ｎ－Ｓ方程,并对激波－边界层相互作用问题进行了计算．结果表明,该方法可捕获激波与边界层相互作用的各种现象,显示了优良的数值模拟性能。     

重味展开下的0~－重介子束缚态

用瞬时近似下的Ｂｅｔｈｅ－Ｓａｌｐｅｔｅｒ（Ｂ－Ｓ）方程，讨论了０－重介子束缚态．运用重味质量展开方法求解方程，计算了一级近似下Ｄ±，Ｄ０，Ｂ±，Ｂ０介子的质量，与实验数据和其它求解方法的计算结果作了比较．     

乙烯基吡咯烷酮－醋酸乙烯酯共聚物对1－苯胺基萘－8－磺酸盐水溶液的荧光特性的影响

将荧光探针１－苯胺基萘－８－磺酸盐（ＡＮＳ）加入到乙烯基吡咯烷酮（ＶＰ）－醋酸乙烯酯（ＶＡＣ）共聚物溶液中，共聚物组成分别为ＦＶＰ＝０．８４；０．７４；０．７０；０．５５（以乙烯基吡咯烷酮结构单元的分子数表示）。实验结果表明：ＶＰ－ＶＡＣ共聚物对ＡＮＳ水溶液的荧光强度增强效应与共聚物中乙烯基毗咯烷酮在链节中的比例有关，其组成为ＦＶＰ＝０．５５的共聚物对ＡＮＳ水溶液有显著的荧光增强效应，相对荧光强度比ＰＶＰ均聚物大一倍，而其他组成的共聚物／ＡＮＳ溶液的相对荧光强度只与溶液中ＶＰ结构单元的含量有关。这种现象说明接近等分子比的乙烯基吡咯烷酮－醋酸乙烯酯共聚物与ＡＮＳ分子间形成的过渡态结构有利于能量转移，能产生较高的量子收率，可作为电子转移反应能量转移介质。在生化反应中，可模拟酶反应机理，因而有一定的理论意义和实际意义。     

Stokes integral of economic growth: Calculus and the Solow model

Economic growth depends on capital and labor and two-dimensional calculus has been applied to economic theory. This leads to Riemann and Stokes integrals and to the first and second laws of production and growth. The mathematical structure is the same as in thermodynamics, economic properties may be related to physical terms: capital to energy, production to physical work, GDP per capita to temperature, production function to entropy. This is called econophysics. Production, trade and banking may be compared to motors, heat pumps or refrigerators. The Carnot process of the first law creates two levels in each system: cold and hot in physics; buyer and seller, investor and saver, rich and poor in economics. The efficiency rises with the income difference of rich and poor. The results of econophysics are compared to neoclassical theory.     

Ohmic Contacts to ZnSe-Based Materials

The formation of ohmic contacts to n- and p-type ZnSe is reviewed. The mechanisms for forming reasonable low-resistance ohmic contacts to n-ZnSe are well understood. This results from the fact that the Fermi energy level of ZnSe is unpinned and metals with sufficiently large work functions can make contact to n-type material. However, the situation is reversed for p-ZnSe where a large band gap and large electron affinity make it impossible to find metals with sufficiently large work functions to create an ohmic contact. Instead, the use of HgSe to form low barrier height Schottky contacts and of ZnSe/ZnTe multiple quantum wells (MQWs) to form ohmic contacts is reviewed. Although the MQWs can be used to form ohmic contacts to p-ZnSe, they degrade at high temperatures and high current densities. This is reviewed and shown to be a serious problem for applications to laser diodes.     

Multistep processes in nuclear reactions

Recent applications of the theory of Feshbach, Kerman and Koonin to analyse multistep processes in nuclear reactions are described, and illustrated by detailed comparisons with a range of experimental data for neutron and proton reactions. The techniques used to distinguish between the multistep direct, multistep compound, compound and collective contributions to the cross-sections are described, and their effectiveness assessed. Particular attention is devoted to recent analyses that take into account the transitions from the multistep direct to the multistep compound chain and also to those that evaluate the collective contributions to the continuum region. The variation of the effective nucleonnucleon interaction with incident energy and target nucleus is studied, and the possibility of a parameter-free calculation is discussed. The extensions of the theory to include multiparticle emission from the direct chain and also to studies of alpha-particle emission are described.     

Evaluation of a contraceptive device with MR imaging.

The purpose of this investigation is to evaluate the positioning and to confirm the volume concept of the Lea's Shield diaphragm utilizing MR imaging. We evaluated the device in two women, one nulliparous and one multiparous. We were able to comprehensively evaluate the device in both patients and answer all questions regarding anatomical positioning and aspects pertaining to the morphology of the device relevant to its function. MRI may be effectively utilized to evaluate contraceptive devices and their relationship to adjacent anatomical structures. This may enhance the gynecologist's clinical assessment of its correct positioning and efficacy.     

National nanotechnology partnership to protect workers

Nanotechnology is predicted to improve many aspects of human life. By 2015, it is estimated to represent $3.1 trillion in manufactured goods. Data is emerging that exposure to nanomaterials may pose a health risk to workers. If the economic promise of nanotechnology is to be achieved, ways need to be found to protect nanotechnology workers now. The Occupational Safety and Health Act of 1970 (OSHAct) gave the responsibility to protect workers to the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) through research, standards adoption, and standards enforcement. Since 1980, adopting new occupational health standards has grown more complex. The increased complexity has greatly slowed efforts to adopt protective standards for toxic agents that are well-known to pose significant risks. The likelihood of rapidly adopting standards to protect workers from nanomaterials, whose risks are just emerging, seems even more unlikely. Use of the OSHAct’s general duty clause to protect workers also seems uncertain at this time. In the interim, a national partnership led by NIOSH involving nanotech manufacturers and downstream users, workers, academic researchers, safety, and health practitioners is proposed. A National Nanotechnology Partnership would generate knowledge about the nature and the extent of worker risk, utilize that knowledge to develop risk control strategies to protect nanotechnology workers now, and provide an evidence base for NIOSH recommendations to OSHA for a nanotechnology program standard at a future date.     

Modifications to functional and biological properties of proteins of cowpea pulse crop by ultrasound-assisted extraction

Natural resource depletion, negative environmental effects and the challenge to secure global food security led to the establishment of the Sustainable Development Goals (SDGs). In need to explore underutilized sustainable protein sources, this study aims at isolating protein from cowpea by ultrasound-assisted extraction (UAE), where the techno-functional characteristics of the protein isolates were studied at different sonication conditions i.e., 100 W and 200 W at processing times ranging from 5 to 20 min. The US at 200 W-10 min produced the optimal results for all properties. In this process combination, there was an increase in protein yield, solubility, water-holding capacity, foaming capacity and stability, emulsion activity and stability, zeta-potential, and in-vitro protein digestibility from 31.78% to 58.96%, 57.26% to 68.85%, 3.06 g/g to 3.68 g/g 70.64% to 83.74%, 30.76% to 60.01%, 47.48% to 64.26%, 56.59% to 87.71%, –32.9 mV to −44.2 mV and 88.27% to 89.99%, respectively and particle size dropped from 763 nm to 559 nm in comparison to control. The microstructure and secondary-structure alterations of proteins caused by sonication were validated by SEM images, SDS-PAGE, and FTIR analyses. Sonication leads to acoustic cavitation and penetrate the cell walls, improving extraction from the solid to liquid phase. After sonication, the hydrophobic protein groups were exposed and proteins were partially denatured which increased its functionality. The findings demonstrated that UAE of cowpea protein improved yield, modify characteristics to fit the needs of the food industry, and contribute to achieving SDGs 2, 3, 7, 12, and 13.     

Two-dimensional detector software: From real detector to idealised image or two-theta scan

Abstract

Detector systems introduce distortions into acquired data. To obtain accurate angle and intensity information, it is necessary to calibrate, and apply corrections. Intensity non-linearity, spatial distortion, and non-uniformity of intensity response, are the primary considerations.

It is better to account for the distortions within scientific analysis software, but often it is more practical to correct the distortions to produce ‘idealised’ data.

Calibration methods and software have been developed for single crystal diffraction experiments, using both approaches. For powder diffraction experiments the additional task of converting a two-dimensional image to a one-dimensional spectrum is used to allow Rietveld analysis. This task may be combined with distortion correction to produce intensity information and error estimates.

High-pressure experiments can introduce additional complications and place new demands on software. Flexibility is needed to be able to integrate different angular regions separately, and to produce profiles as a function of angle of azimuth. Methods to cope with awkward data are described, and examples of the techniques applied to data from high pressure experiments are presented.     

Polymer composites for thermal management: a review

The aim of this review article is to consolidate the important research works dedicated to polymers which are mainly used target material for heat transfer applications. The requirement of present day heat transfer equipment is compactness, lightweight, manufacturability, and lower cost. Materials like copper and aluminum though have better thermal conductivity but they are expensive and also heavy. Polymers are cheaper and easy to manufacture, recycle though they have sufficiently lower thermal conductivity compared to copper and aluminum. Polymer materials are thermally insulating material. It is too difficult to improve the amorphous nature of polymer material in order to achieve high thermal conductivity. One key path to increase the thermal conductivity of a polymer is to reinforce high thermal conductive fillers in the host matrix. In this review paper, an attempt is made to explore and summarize various key paths suggested by the researchers to develop high thermal conductive polymer composites.     

Role of waveguide and surface plasmon resonances in surface-enhanced Raman scattering at coldly evaporated metallic films

A film surface, modeled by a grating with rectangular grooves, is shown to give rise to both short and long ranged enhancements due to excitation of planar surface plasmon resonances, and to short ranged, more intense, enhancements due to excitation of waveguide resonances. The latter type of enhancement is shown to become more intense as the ratio of grating period to groove width increases and to be able to account for experimentally observed SERS signals at very low as well as at higher temperatures.