谈期刊目录数据库的建设与期刊工作的发展

论述了期刊目录数据库建设的准备工作、建库时的注意事项以及建库后期刊部工作的发展方向。     

Loess in the Tian Shan and its implications for the development of the Gurbantunggut Desert and drying of northern Xinjiang

Eolian loess is widely distributed on the various geomorphic surfaces between 700–2400 m a.s.l. on the northern slope of the Tian Shan. It is formed in a synchronous manner with dust transported from the Gurbantunggut Desert in the Junggar Basin. The thickest section of loess was found in the Shawan and Shihezi regions. Paleomagnetic and climatic proxy analyses of over 71 m of a loess-paleosol sequence on the highest terrace of the Qingshui He (River) in the Shawan show that the paleomagnetic Bruhues/Matuyama (B/M) boundary lies at the bottom of paleosol S8, at a depth of 69.5 m, and the bottom of the sequence was estimated to be ∼0.8 Ma. This implies that the extremely dry climatic conditions in the Junggar Basin and the initial Gurbantunggut Desert were present at least by 0.8 Ma. High-resolution grain size series demonstrate that this area and desert expansion experienced two dramatic periods of desert expansions that occurred at ∼0.65 Ma and 0.5 Ma, respectively; and the subsequent continuous enhancement led to the environment presently observed. This tremendous environmental effect, caused by large-scale expansion of the desert and arid region of inner Asia, might be an important driving force for the global temperature drop that occurred in the mid-Pleistocene.     

The 1997–1998 warm event in the South China Sea

A strong warm event happens during spring 1997 to spring 1999 in the South China Sea. Its intensity and duration show that it is the strongest event on the record over the past decades. It also corresponds with the severe flood over the valley of the Yangtze River and a couple of marine environmental events. This note addressed the evolution process by using several data sets, such as sea surface temperature, height and wind stress in addition to subsurface temperature. The onset of the warm event almost teleconnects with the El Niño event in the tropical Pacific Ocean. Summer monsoon is stronger and winter monsoon is weaker in 1997 so that there are persistent westerly anomalies in the South China Sea. During the development phase, the warm advection caused by southerly anomalies is the major factor while the adjustment of the thermocline is not obvious. Subsequently, the southerly anomalies decay and even northerly anomalies appear in the summer of 1998 resulting from the weaker than normal summer monsoon in 1998 in the South China Sea. The thermocline develops deeper than normal, which causes the downwelling pattern and the start of the maintaining phase of the warm event. Temperature anomalies in the southern South China Sea begin to decay in the winter of 1998–1999 and this warm event ends in the May of 1999.     

一种改进的点定位算法

通过对传统的点定位算法——奇偶法则算法的分析 ,提出了一种改进的奇偶法则的实现算法 .在改进算法中 ,从待判定点引出的射线定义为与 x轴平行且与其同向 ,对射线与区域边界边的相交情况进行了分类处理 .通过分析射线与边界边的位置关系 ,只有少数情况需要计算其交点 ,而大部分情况只需简单比较即可得出相交情况 .当射线穿过两条相邻边界边的交点时 ,根据定义的法则 ,只进行一次相交情况的判定 .因此 ,改进算法减少了计算交点的次数 ,提高了点定位的效率 .最后通过实际应用 ,对传统算法与改进算法在同样条件下的处理时间进行了比较     

声波早期检测气侵数据处理与程序设计

声波可被用于早期检测气侵 ,然而由于钻井现场存在强干扰 ,泵的波动信号 (声源 )难以提取。通过采用特殊的软、硬件技术 ,可提高声波传播中的抗干扰能力。对强干扰下的声波信号采用两级差动放大 ,采用相位超前型三运放二阶电路 ,实现一级增益线性调节。利用概率密度技术捕捉声信号的微小变化 ,能够有效地识别气侵并报警。采用智能滤波线技术 ,有利于计算机识别较强干扰下声波波形周期 ,并计算时间延迟     

基于工作流的PDM应用系统研究

介绍了工作流管理的现状和 PDM系统的体系结构 ,提出一种以工作流管理为核心的PDM系统解决方案 ,通过在 PDM系统中集成 STEP标准建立信息模型和数据交换 ,增强系统在信息和应用集成的过程中的适应性和开放性 ,提供基于 Internet/ Intranet的共享零件库和标准工程手册数据库 ,将工程设计和管理人员解放出来 ,提高产品设计和资源利用率 .     

照相机的可靠性增长分析

应用可靠性增长的原理和方法,对DF-1ETM照相机进行了试验;对试验结果进行了故障分析,并找出了故障薄弱环以及针对薄弱环所进行的3个增长循环周期,解决了原有照相机故障率高、可靠性差的问题;介绍了该照相机可靠性增长的数学模型和拟合模型的方法。     

卷弧翼身组合体的自滚转特性

介绍了卷弧翼身组合体自滚转特性的风洞试验研究.给出了测力试验和测压试验结果.测力试验结果表明,卷弧翼弹型存在自诱导滚转力矩.测压试验结果表明,卷弧翼弹型自诱导滚转力矩产生的原因在于,卷弧翼凹凸两面的压力不等,形成自诱导法向力.在同样相对厚度下,变厚度卷弧翼的载荷分布与等厚度卷弧翼的载荷分布相差很小,气动设计时可以不考虑厚度变化的影响。     

EMG信号的一种合成方法研究

利用改进了的肌电信号模型，完成了单纤维动作电位（ＳＰＡＰ）和运动单位动作电位（ＭＵＡＰ）的计算机模拟．以此为基础，结合肌肉组织的生理结构和肌电信号的产生原理，首先由多路ＳＰＡＰ信号经过符合生理特性的变换处理后，合成一路ＭＵＡＰ信号，然后考虑人体组织对肌电信号的衰减作用，对具有不同发放率的ＭＵＡＰ序列进行ＥＭＧ信号的合成．这种人工合成的ＥＭＧ信号有助于从理论上研究肌电信号的发放率和传导速度等特性，并将为肌电信号的分解给出一个合理标准．     

燃油炉火焰辐射的双色法实验研究

在双色法测试系统的标定和改善测量计算精度方面进行了有益的尝试， 验证了测试系统的良好线性，并利用自行装配的燃油炉和双色法测试系统对 燃油炉火焰温度和吸收系数进行了测量．结果表明，对火焰温度进行测量计 算时，在一定条件下可以忽略壁面反射和辐射的影响，而对单色辐射率、单色 吸收系数和碳粒浓度的测量则必须考虑它们的影响．