手持导航设备的电磁干扰定位和整改

手持导航产品中,电磁干扰对产品性能的影响巨大。该文重点描述PND产品中EMI定位和整改问题的一般分析方法和手段,即通过组合使用通用的电、磁场探头,GPS有源天线,电压探头进行近场扫描,准确定位PND中的干扰源和干扰路径,并举例说明这些方法的应用。     

全球导航卫星系统的现状及其产业发展综述

本文介绍了目前国内外主要的卫星导航系统的发展现状,总结了卫星导航产业的特点、发展趋势及其应用前景等,指出了我国卫星导航产业市场现状、存在的问题并提出产业规划的建议。     

PND脉冲中子衰减能谱测井应用实例分析

本文剖析了PND脉冲中子衰减能谱测井求含水饱和度的两种不同测量方式,即俘获截面∑和非弹性散射数据CATO。采用非弹性散射数据CATO测量方式,通过对实际测井资料的处理,在矿化度高于25000mg/L的套管井中求取含水饱和度,取得了良好的效果。     

用PND测井资料求取水平井储层含水饱和度

针对水平井储层含水饱和度解释中存在的难题。根据PND测井资料中具有一定矿化度的地层水的俘获截面大而油气烃类的俘获截面相对较小的特点，来计算储层的含水饱和度和区分油水层。指出该方法的应用条件是：地层水矿化度不小于50000mg/L，孔隙度不小于15%。应用实例证明了该方法的有效性。     

Numerical study of particle dispersion behind a sudden expansion geometry and its effect on step heights

Numerical simulations were performed for dilute gas–particle flows over two-dimensional turbulent backward-facing step geometry to examine the effects of step heights on turbulent separated flow with particles and their inherent dispersion behaviour. Eulerian two-fluid model along with RNG based k– model is used as the turbulent closure to study this mechanism. However, additional turbulence transport equations are solved to better represent the combined gas–particle turbulence interactions. Two different particle classes with different Stokes number are considered in this study in order to gain a better understanding of the particle behaviour/response to the mean flow and also their effective dispersion. This study helps to better understand the effective particulate viscosity used by two-fluid practioners in order to better capture dispersed phase distribution. The mean flow of the carrier phase along with the dispersed particulate phase is simulated and compared against the experimental data for the step height with maximum expansion ratio (ER). The main objective of this process is to streamline the code to replicate the experimental results and use it further to simulate various other step heights and their particle distribution. This is carried out by keeping the inlet velocity and the flow exit width the same throughout all the different step heights. On the general standing, it is observed that the modelled particulate viscosity works in tandem to the particle number density (PND) of the dispersed phase particles.     

汽车音响系统中的PND导航显示系统的设计

在介绍汽车音响导航系统基本知识的基础上,针对可热插拔导航PND设备提出了一种显示系统的思想和设计实现。     

PND测井识别气层在塔河油田的应用

介绍了利用PND测井资料进行气层识别的方法．即利用近探测器计数率和远探测器计数率以一定比例进行重叠的方法识别气层。该方法具有快速、直观的特点。并且在塔河油田砂岩储层中取得了很好的效果。     

基于移动网络的车载PND导航应用

本文对车载通信导航模式进行了介绍和分析,论述了中国移动车载PND导航业务的服务模式及业务特点,并展望了业务未来发展方向。     

Significant cost savings using a newly developed single-process technology compared to conventional processes for treating high-strength effluents

This study investigates the performance of a newly developed technology, known as simultaneous anaerobic oxidation/partial nitrification–denitrification (SAO/PND), for treating strong wastewater under laboratory conditions. Excellent results are achieved, with maximum chemical oxygen demand (COD) and nitrogen removal of 98% and 96%, respectively, when treating synthetic wastewater with influent 4120 mg/L COD and 210 mg/L NH₄⁺–N. Appropriate living environment in this single-process technology favoured the co-existence of various bacterial communities, and removal mechanisms by these organisms are identified and confirmed. The results showed that the single-process SAO/PND technology required 95% and 90% less oxygen compared to conventional aerobic processes and combined systems, respectively. Furthermore, this newly developed technology produced 60% and 44% less sludge, respectively, in comparison with the mentioned conventional systems. This study shows that the single-process SAO/PND technology is a promising sustainable alternative to conventional systems, as it combines high efficiency and cost-effectiveness with simple operation and maintenance requirements.