镁合金空心坯料挤压成形工艺研究

对挤压成形过程中的坯料尺寸及模具形状对成形的影响进行了计算机模拟。由模拟结果可知,在采用无芯轴凸模挤压时,挤压力随着行程的增加而增大,随着空心坯料内径的增大,挤压力增加的速度减慢,但最大挤压力变化不大。在采用带芯轴凸模挤压时,最大挤压力明显减小,随着芯轴直径的增加,最大挤压力是逐渐下降的,最大挤压力可以降低25%以上。     

湖南常见辣椒品种游离氨基酸主成分分析及综合评价

游离氨基酸参与辣椒中风味物质的合成,其种类及含量与辣椒品种密切相关.采用高效液相色谱-串联质谱法对湖南常见大红椒、青尖椒、螺丝椒、小米椒、小红椒、大青椒6种辣椒的游离氨基酸进行分析,明确不同辣椒品种游离氨基酸组成差异,以期为合理开发和利用辣椒资源提供理论依据.结果表明:6种辣椒中共检出24种游离氨基酸,其中青尖椒、螺丝...     

Find the firn line! The suitability of ERS-1 and ERS-2 SAR data for the analysis of glacier facies on Icelandic icecaps

Icelandic Icecaps are sensitive indicators of climatic fluctuations. Glacier facies boundaries can be identified using remote sensing techniques; SAR data represents the first real opportunity to monitor glacier facies, without cloud attenuation at regular or inter-annual intervals. This study assesses the overall suitability of the data for the monitoring of glacier facies and in particular the firn line altitude (FLA) on Icelandic Icecaps. The results show that the firn line can be identified and located to within +/- 20-40m (vertically). These results were validated using aerial photograph and ground data. RAIDS (Rapid Information Dissemination System) processed data were found to compare favourably with other satellite data for this type of application.     

滤板施工技术比较

滤板是水处理滤池工艺的重要组成单元，文章对预制滤板和整体现场浇筑滤板的施工技术进行了比较说明，并得出了滤板施工技术选型结论。     

Noise Reduction Methods for Weighing Lysimeters

Mechanical vibration of the grass and crop weighing lysimeters, located at the University of California West Side Field Research and Extension Station at Five Points, Calif. generated noise in lysimeter mass measurements and reduced the quality of evapotranspiration (ET) data. The estimated power spectral density (PSD) for grass lysimeter mass data acquired at 1.3?ms intervals contained a large peak at 11?Hz. Crop lysimeter data produced similar peaks at frequencies greater than 1?Hz. An effective method for eliminating this noise source is arithmetic averaging of the data, which should be acquired sufficiently rapidly to avoid aliasing. The PSD also increased with decreasing frequency in the range 1.0–0.1?Hz. This noise was addressed by Savitsky–Golay (SG) filtering using 7-, 11-, and 15-point filters. Each filter was applied to the same data set consisting of 2,560 measurements taken during a 1-min interval every 10?min over a 26.3-h period. Noise reduction factors, defined as the ratio of standard deviation of filtered lysimeter mass to standard deviation of unfiltered mean values of lysimeter mass for subsequences of the same data, were 0.90, 0.88, and 0.86 for the 7-, 11-, and 15-point filters, respectively. For the daytime data only, the factors were 0.88, 0.85, and 0.83. The SG filters were more effective during daytime when most of the lysimeter ET occurs. These methods are simple enough to be programmed into commercially available dataloggers for real time filtering. Hourly averages of the standard deviations of lysimeter mass measurements bear a distinct nonlinear relationship to hourly mean wind speed confirming earlier suppositions that wind loading causes noise in counterbalanced weighing lysimeters.     

The Volkov-like Coulomb Continuum

Abstract

We derive a field-dressed Coulomb continuum state and discuss its application in the calculation of intense-field multiphoton ionizations.     

三相异步电动机电磁设计参数与电磁噪声细化频谱特性的分析

本文阐述了三相异步电动机气隙电磁力波的特性与电磁设计参数的关系,特别是推导出包含有定转子槽配合分量的计算电磁力波频率的新公式.按新公式计算了两台样机电磁力波频率,并与实测的电磁噪声细化(zoom)频谱特性进行了对比,初步间接地证实了两者之间的某种联系.     

环氧型马来酰亚胺树脂的研究

运用分子设计原理合成了分子骨架中同时含有环氧树脂和马来酰亚胺环的环氧型马来酰亚胺树脂。根据合成中原料配比的不同设计制成了三种ＥＭ树脂，研究了它的反应性和固化树脂的性能。结果表明，ＥＭ树脂具有良好的成型工艺性，优良的力学性能和耐热性且随ＥＭ树脂组成含量的变化而有规律地变化。     

双马来酰亚胺型基体树脂的配比优化设计

采用二次回归正交设计安排试验,建立配比与性能之间的回归方程.检验表明,所得回归方程非常显著,在一定范围内可较准确地预测和控制材料的性能;利用回归方程绘制性能等高线图,所得图形可直观地反映配比对材料性能的影响规律.采用逐步搜索法求解回归方程,确定了一种耐高温.韧性双马来酰亚胺型基体树脂的最优配比.     

Differential binding of tropane-based photoaffinity ligands on the dopamine transporter

Benztropine and its analogs are tropane ring-containing dopamine uptake inhibitors that produce behavioral effects markedly different from cocaine and other dopamine transporter blockers. We investigated the benztropine binding site on dopamine transporters by covalently attaching a benztropine-based photoaffinity ligand, [125I]N-[n-butyl-4-(4"'-azido-3"'-iodophenyl)]-4', 4"-difluoro-3alpha-(diphenylmethoxy)tropane ([125I]GA II 34), to the protein, followed by proteolytic and immunological peptide mapping. The maps were compared with those obtained for dopamine transporters photoaffinity labeled with a GBR 12935 analog, [125I]1-[2-(diphenylmethoxy)ethyl]-4-[2-(4-azido-3-iodophenyl)ethy l]p iperazine ([125I]DEEP), and a cocaine analog, [125I]3beta-(p-chlorophenyl)tropane-2beta-carboxylic acid, 4'-azido-3'-iodophenylethyl ester ([125I]RTI 82), which have been shown previously to interact with different regions of the primary sequence of the protein. [125I]GA II 34 became incorporated in a membrane-bound, 14 kDa fragment predicted to contain transmembrane domains 1 and 2. This is the same region of the protein that binds [125I]DEEP, whereas the binding site for [125I]RTI 82 occurs closer to the C terminal in a domain containing transmembrane helices 4-7. Thus, although benztropine and cocaine both contain tropane rings, their binding sites are distinct, suggesting that dopamine transport inhibition may occur by different mechanisms. These results support previously derived structure-activity relationships suggesting that benztropine and cocaine analogs bind to different domains on the dopamine transporter. These differing molecular interactions may lead to the distinctive behavioral profiles of these compounds in animal models of drug abuse and indicate promise for the development of benztropine-based molecules for cocaine substitution therapies.