Parallel implementation of molecular dynamics simulation for short-ranged interaction

A parallel molecular dynamics simulation method, designed for large-scale problems, employing dynamic spatial domain decomposition for short-ranged molecular interactions is proposed. In this parallel cellular molecular dynamics (PCMD) simulation method, the link-cell data structure is used to reduce the searching time required for forming the cut-off neighbor list as well as for domain decomposition, which utilizes the multi-level graph-partitioning technique. A simple threshold scheme (STS), in which workload imbalance is monitored and compared with some threshold value during the runtime, is proposed to decide the proper time for repartitioning the domain. The simulation code is implemented and tested on the memory-distributed parallel machine, e.g., PC-cluster system. Parallel performance is studied using approximately one million L-J atoms in the condensed, vaporized and supercritical states. Results show that fairly good parallel efficiency at 49 processors can be obtained for the condensed and supercritical states (∼60%), while it is comparably lower for the vaporized state (∼40%).     

The ontogeny of fear-potentiated startle: Effects of earlier-acquired fear memories.

Research has shown that learned fear emerges in a response-specific sequence. For example, freezing is observed at a younger age than is potentiated startle (P. Hunt & B. A. Campbell, 1997). The present study shows that the age at which a specific learned fear response emerges is influenced by the animal's early experiences. Specifically, fear potentiation of startle emerges earlier in development if the rat is given prior fear conditioning to a different stimulus. Some constraints of this "facilitation" effect are determined in follow-up experiments. This facilitation effect may provide a novel way of testing the development of the neural circuits underlying learned fear. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Possible induction by estrous cows of pheromone production in penmates

The primary attractive odors of estrous cows apparently induced production of secondary attractive odors in penmates. Presence of both odors was reflected by the bull's olfactory behavior. The inducing effect was strongest on the day of estrus and the day before. The information content of the primary and secondary odors was different since a sexually experienced bull was able to distinguish olfactorily between estrous and nonestrous cows. The secondary odors attracted at least transient bull's interest, resulting in sniffing, urine tasting, and flehmen reactions, but not mounting attempts. The induced production of attractive odors and lack of precise smell discrimination in penmates may lead to erroneous detection of estrus in cows and heifers that show false estrous signs without corresponding changes in their reproductive organs. Similar factors may be involved in triggering mounting among feedlot steers (buller steer syndrome).     

最佳阈值分割算法在肺癌细胞识别系统中的应用

肺癌细胞识别中,图像分割是其中重要的一环.其准确性直接影响到肺癌的早期诊断以及后续治疗.本文提出一种最佳阈值分割算法,通过分析直方图的方法确定最佳的阈值.最后对图像的孔洞进行填充,以达到特征提取的要求.实验证明此算法是有效的.     

应用成藏门限理论评价吐哈盆地前侏罗系油气资源潜力

针对油气区远景资源潜力评价中缺乏定量依据的问题,提出了一种评价油气远景资源潜力的新概念———成藏门限,论述了油气成藏门限的地质含义及地质证据,并应用基于成藏门限理论开发的"油气成藏体系定量评价系统"对吐哈盆地前侏罗系油气资源潜力进行了定量评价,计算其油、气远景资源潜力分别为3.354×108t和2652×108m3,原油资源探明率仅为15%,表明吐哈盆地前侏罗系仍具较大勘探潜力。      

Gas chromatographic analysis of fragrances in palm-based white soaps

Four commercial soap fragrances 1,2,3, and 4 were incorporated in palm-based white soaps and made into bars. The soap bars were stored at 25°C and 40°C for three months. The headspace gas-chromatographic volatiles, fragrance odor intensity and whiteness analyses of the soap samples were carried out at 10-day intervals. By means of gas chromatography and mass spectrometry, some of the headspace gas-chromatographic peaks were identified. These peaks were useful in monitoring the fragrance components. For example, fragrance 4 contains the components limonene and citronellal which are known to possess a citrus odor component. Fragrance odor intensity scores showed that the intensity of the fragrances in the soap base was the same for all. Results also showed that most of the fragrances had the same effect on the whiteness of palm-based white soaps, except for fragrance 2 which gave a pink color to the white soaps. Equations were established between the fragrance odor intensity and area under the gas-chromatographic peaks. The equation can give useful information on the fragrance odor intensity by calculating the area of the chromatographic peaks; the fragrance odor intensity is a reflection of the fragrance retention in palm-based soaps.     

Mssbauer 谱仪数据接口的改进

对Ｍｏｓｂａｕｅｒ谱仪数据接口进行了改进。通过简化电路，以软件实现硬件的功能。在测量中省却了单道分析器，使测量系统更为简单、可靠和高效。     

振荡限幅器型卫星电视接收解调器

本文着重介绍了振荡限幅器型门限扩展解调器的工作原理及工作条件,同时设计了一种振荡限幅器型卫星电视接收解调器。该解调器具有电路简单,性能良好,具有较低接收门限等特点,可用于接收苏联714MHz卫星电视节目。此解调器特别适用于一些接收场强较弱的地区。实验表明,该解调器门限改善量约可达3dB。     

多级安全关系数据库系统审计功能的设计

本文简要地介绍了多级安全关系数据库系统和计算机系统的审计，强调指出了多级安全关系数据库系统审计功能的设计必须遵循多级安全策略，并就审计粒度的选择，审计开关和阈值的设置，审计日志的维护和查询等方面的设计作了详细的讨论。     

低渗透油藏超前注水理论及其应用

低渗透油藏最显著的特征是存在启动压力梯度和介质变形现象,这使其在开发过程中渗流阻力增大、单井产量降低,递减速度加快,稳产难度加大,并降低最终采收率。对低渗储层启动压力梯度和介质变形进行了物理模拟实验,定量描述了两者的非线性变化规律,分析了介质变形对储层物性参数的影响。通过室内实验、渗流理论、数值模拟以及矿场试验研究,建立了低渗透油藏非线性渗流数学模型,提出了在超前注水期运用保持合理地层压力水平、注水压力、注水强度和注水时机的开发技术,在长庆等低渗透油田现场应用后取得较好的开发效果,提高单井产量15%~20%。