ZL114A高强铸造铝合金的焊接

ZL114A高强铸造铝合金用于生产导弹壳体等零件。由于铸造工艺的影响，铸造存在气孔、疏松、夹渣、裂纹、偏析、缺损等缺陷，用焊接的方法修复铸造缺陷可以取得显著的经济效益，对交流氩弧焊补ZL114A高强铸铝件的工艺过程加以介绍。     

牵引式火炮行军安全保护系统研究

根据炮兵部队和军事院校机动训练的需要，针对拉练过程中经常出现的因火炮机械原因产生的故障，为及时有效地排除火炮行军过程中存在的隐患，设计“牵引式火炮行军安全保护系统”，结合火炮的机械特点，设计环形垫片式测力传感器，采用曲线拟合的方法对任意路面进行测量。     

以模型为素质平台,打破知识教育的格式化

模型以简洁优美，严谨规范的表达方式，把科学的探索精神，研究方法，思维方式，推理艺术融合，交织在地卢；清晰地勾勒了科学的发明特点和创造本质，把教学内容直接引入理论层面和探索形式之中。在模型的视角下对教学内容进行编辑，提炼，诠释，引发，甚至包装，把知识的思想性，相关性，包容性，层次性，以框架和网络的形式，巧妙而又具体地表现出来。     

基于Client/Server应用层包跟踪技术的CSPA软件开发和仿真

本文介绍了基于跟踪 Client和 Server端的应用层包 ,开发了得到响应和请求时间及包大小分布的 PDF的应用软件 CSPA,通过对 PDF的分析而建立通用 PDF数学模型并用于网络仿真的应用过程     

RNA splicing of bacterial genes in eukaryotes

The presence of intervening sequences or introns in eukaryotic genes has been known for more than 20 years, and the mechanisms underlying RNA splicing have been studied in depth both genetically and biochemically. In recent years, however, an increasing number of bacterial genes have been introduced into higher eukaryotes as important tools for genetic studies. Their gene products are frequently used as an indirect measure for cell type-specific promoter activity, as, for example, in the case of chloramphenicol acetyl transferase (CAT assay) or beta-galactosidase. Here we show that RNA splicing of two prokaryotic genes encoding site-specific DNA recombinases occurs in eukaryotic cells. In one case, splicing is only observed after treatment of cells with the cytokine alpha interferon. We further demonstrate that mutating an intragenic donor splice site in a bacterial gene apparently activates a second, alternative splicing pathway. In conjunction with previous reports, our findings should also be regarded as a warning that splicing of bacterial genes in higher eukaryotes is a more common phenomenon than presently recognized, which may be difficult to overcome and may cause problems in the interpretation of experimental results.     

Human exposure to heavy metals in East Greenland I mercury

The concentration of mercury in 178 blood samples and 32 hair samples from the Angmagssalik district in East Greenland has been determined.For Greenlanders mercury concentrations are highly dependent on the amount of seal eaten. In the most heavily exposed group (eating more than six meals of seal per week), a significant positive correlation between blood mercury and age was demonstrated. No differences according to sex were demonstrated when the mean values were corrected for influence of age. In the most heavily exposed group, a mean value of 62.5 μg Hg/l was found, while in the group eating 1 meal of seal or less per week, the mean value was 22.2 μg Hg/l. In the control group consisting of Danes living temporarily in the district, the mean blood mercury concentration was 5.8 corresponding to the fact that they eat seal only occasionally.Hair mercury concentrations were found to correlate well with blood mercury concentrations (r = 0.9222). The hair/blood ratio was estimated to 289.It is concluded that the present relatively high mercury exposure in Greenland does not excert any immediate risk of intoxication to the adult population, but supplementary investigation on fetal exposure is needed.     

Resource-Bounded Paraconsistent Inference

In this paper, a new framework for reasoning from inconsistent propositional belief bases is presented. A family of resource-bounded paraconsistent inference relations is introduced. Such inference relations are based on S-3 entailment, an inference relation logically weaker than the classical one and parametrized by a set S of propositional variables. The computational complexity of our relations is identified, and their logical properties are analyzed. Among the strong features of our framework is the fact that tractability is ensured each time |S| is bounded and a limited amount of knowledge is taken into account within the belief base. Furthermore, binary connectives , behave in a classical manner. Finally, our framework is general enough to encompass several paraconsistent multi-valued logics (including S-3, J ₃ and its restrictions), the standard coherence-based approach to inconsistency handling (based on the selection of consistent subbases) and some signed systems for paraconsistent reasoning as specific cases.     

一台220kV电力变压器铁轭拉带故障分析

文章对一台大型电力变压器由于上轭铁心拉带放电引起的油色谱异常现象,经过对色谱数据和运行情况的综合分析,对变压器故障点作出准确判断,现场对该变压器进行了解体检查、处理,对避免此类故障的发生提出了改进建议。     

Multi-month memory effects on early summer vegetative activity in semi-arid South Africa and their spatial heterogeneity

In semi-arid African regions (annual rainfall between 200 and 600 mm), variability of vegetative activity is mainly due to the rainfall of the current rainy season. In most of South Africa, the rainy season occurs from October to March. On average, vegetative activity lags rainfall by 1 to 2 months. The interannual variability in early summer (December to September) normalized difference vegetation index (NDVI) depends primarily on precipitation at the beginning (October to November) of the rainy season. However, once this primary control is removed, the residual interannual variability in NDVI highlights a double memory effect: a 1-year effect, referred to as Mem₁, and a 7- to 10-month effect, referred to as Mem₂. This article aims at better describing the influence of soil and vegetation characteristics on these two memory effects. The data sets used in this study are as follows: (1) a 19-year NDVI time series from National Oceanic and Atmospheric Administration (NOAA) satellites, (2) rainfall records from a network of 1160 rain-gauge stations compiled by the Water Research Commission (WRC), (3) vegetation types from Global Land Cover (GLC) 2000 and (4) soil characteristics from the soil and terrain database for Southern Africa (SOTERSAF). Results indicate that among 20–30% of NDVI variance that is not explained by the concurrent rainfall, one-third is explained by the two memory effects. Mem₁ is found to have maximum effect in the northwest of our study domain, near the Botswana boundary, in the South Kalahari. Associated conditions are open grasslands growing on Arenosols. Mem₁ is less important in the southeast, particularly in open grassland with shrubs growing on Cambisols. Thus, Mem₁ mainly depends on soil texture. Mem₂ is more widespread and its influence is the greatest in the centre, the south and the east of our domain. It is related to rainfall from January to April, which controls, beyond the intervening dry season, the interannual variations of NDVI (December to September) at the beginning of the next rainy season. Through these new findings, this article emphasizes again the high potential of remote-sensing techniques to monitor and understand the dynamics of semi-arid environments.