DAR ES SALAAM

Countries in transition often experience increased levels of crime, making their citizens vulnerable to the exploits of criminals. The lack of reliable statistics hampers the development of sound crime reduction strategies. This essay considers the value of victim surveys as additional sources of information to augment official police data. It presents the findings of such a survey undertaken in Dar es Salaam and compares them with findings obtained in similar surveys of Cape Town, Durban, Pretoria and Johannesburg. The information obtained in the survey conducted in Dar es Salaam provides valuable insights into crime rates and patterns. In comparing the results of the survey in Dar es Salaam, some interesting trends emerged around the theft of vehicle parts and vehicle theft, violent crimes, the levels of violence employed in burglaries and the use of weapons. The information gleaned from these surveys will go far in developing crime reduction strategies and measures that will be effective and appropriately targeted.     

Don't stop with Joint Forces Command … cut AFRICOM too

Abstract

The United States Africa Command (AFRICOM) has been a military success but a strategic messaging failure. The United States’ relationships across Africa cannot be boiled down to military affairs. This paper argues that Africa has many more opportunities than challenges and thus requires a more balanced foreign policy solution from Washington DC than a new military command. For the military engagement that does need to take place, a more low-profile approach would benefit the United States in Africa.     

Terrorism,insurgency, kidnapping,and security in Africa's energy sector

Energy continues to serve as the bedrock of modern economies and the main driver of modern society. For Africa, the production and supply of energy resources such as crude oil, natural gas, uranium, coal, biomass, biofuels and other renewables are an important source of employment, rents, taxes, royalties and profits. This sector brings in several tens of billions of dollars of revenue annually. The production and delivery of such resources, however, depend on critical infrastructures such as pipelines, refineries, processing plants, terminals, rigs, electrical energy pylons, substations, pump stations, vessels, and tankers. These infrastructures have been attacked by terrorists, insurgents, vandals and saboteurs, all of whom see them as targets against which to register their grievances and extract concessions from the state. This paper is a chronological account of some of the documented incidents of terrorism, insurgency, kidnapping, destruction, sabotage, and human casualties suffered in the oil and gas sectors in Africa between 1999 and 2012. It is based on data extracted from the databases of the RAND Database of World Terrorism Incidents and the University of Maryland's Global Terrorism Database (GTD).     

机动管线流量在线实时监测技术研究

输送流量在线实时监测是准确掌握机动管线运行工况、优化运行方案、分析判断泄漏的关键之一。分析了容积式、速度式和差压式等常用流量监测技术的技术特征与使用条件,根据机动管线的作业特点和要求,优选出涡街流量监测技术作为该管线系统的流量在线实时监测技术;分析了机动管线输送过程中管道振动对涡街流量计计量精度的影响,提出了几种不同的抗振防干扰技术,并应用于机动管线涡街流量监测装置的研制。样机试验表明,采用抗振技术的涡街流量监测装置检测精度能满足机动管线流量在线实时监测需求。     

某型自行加榴炮抽筒过程动力学分析

分析了某型自行加榴炮钢质药筒不抽筒产生的原因,简述了火炮抽筒机构改进的措施,建立了抽筒过程的动力学方程,分别对四种方案进行了计算。     

植物油交联共聚阻尼材料的研究

为扩大阻尼材料的原料来源,降低成本,提高阻尼性能,研究以植物油(蓖麻油、棉子油、桐油)为原料,合成环氧植物油及桐油酸酐,将桐油酸酐与环氧植物油进行本体聚合,制得了一系列 AB—交联共聚物。对试样进行动态力学测试,结果表明,该共聚物具有较高的阻尼因子(tanδ最高在1以上),较宽的阻尼温域。在40～60℃时,tanδ值持续大于0.3,是一类成本低廉、阻尼性能良好的新型阻尼材料。     

中碳钢碳化物相位的应变诱发快速球化

中碳钢中的片状共析碳化物,可在A_(c1)点之下较高的温度进行适量的变形即可在形变过程中实现球化;停止变形后继续在变形温度停留1～2小时,可使碳化物球通过奥斯瓦尔德熟化达到尺寸均匀化和粗化,同时使铁素体基体完成再结晶。     

CCD在钢板计数中的应用研究

长期以来,一直依赖于人工计数叠层钢板,劳动强度大,精确度低,为解决这一困扰生产的难题,笔者研制了CCD钢板计数装置。在单片机系统的控制下,CCD象感器利用操作简单的光学机构获取叠层钢板侧面的图象信息,经处理后,形成能反映钢板叠层变化的窄脉冲序列,该脉冲序列经单片机分析,精确地判断出叠层钢板的张数。现场使用,结果准确无误。     

pH 值对碳钢在 3%NaCl 溶液中极化行为的影响

采用准稳态的极化方法研究了两种碳钢在不同ｐＨ值的３％ＮａＣｌ溶液中的极化行为,发现：碳钢在３％ＮａＣｌ溶液中发生钝化的临界ｐＨ值约为８．０;当ｐＨ＞８．０时,随着ｐＨ值的增大,致钝及维钝电流逐渐变小,点蚀电位逐渐变正．同时发现ＮＨ＋４对碳钢的极化行为有影响．     

低碳钢中硫化物夹杂物诱发点蚀的机理

选择两种具有典型硫化物夹杂物的碳钢,通过显微腐蚀试验、浸泡试验及带有显微跟踪观察的极化试验考察了点蚀发生的初始过程,结合金相和扫描电镜电子探针分析,提出了碳钢中硫化物夹杂物诱发点蚀的机理。