Some improvements in design of atmospheric ammonia storage tanks of the double integrity type

This paper describes a new atmospheric ammonia storage tank in Iceland. Some modifications have been made to the former common open cup design of double integrity tanks. Another modification is described, dry air is bled under the cladding of the sidewall insulation to protect the insulation from moisture penetration under the vapor barrier which results in frost damages.     

英国北海油田废弃支出减负计划分析

英国北海地区的油气生产经营适用的主要税种包括矿区使用费、石油收入税、附加税和公司所得税.英国政府从2013年开始在原有油气财税条款的基础上制定了废弃阶段的废弃支出减负计划,对石油公司在油气生产经营末期面临巨额废弃支出的状况,给予废弃支出一定比例的减负,这种减负通过税收返还的形式实现.影响税收返还的关键因素包括计算各项税金的基数大小、审批时效以及油气价格波动.基于废弃支出减负计划的内容,石油公司应该合理安排废弃计划,积极跟踪政府审批流程,密切关注国际油气价格走势,使得当年的废弃支出能够最大限度地得到减负.     

A method for determining the flammable limits of gases in a spherical vessel

The current method for determining the flammable limits for a gas in a closed spherical vessel is based on a specification of the maximum pressure increase during the combustion, usually from 5 to 10% of the initial ambient pressure. This approach is completely arbitrary and is not fundamentally based. For most hydrocarbons this pressure boundary and hence the flammable limits are easy to determine experimentally since an abrupt pressure drop occurs at the flammable limits as the fuel concentration in air is adjusted. However, for some species, particularly hydrogen mixed with air, the drop in maximum combustion pressure is not very abrupt and the fuel concentration can range several percentage points depending on the arbitrary criterion used for the flammable limits. This article will discuss a new approach for determining the flammable limits for a gas in a spherical vessel. The approach is based on the maximum second derivative of pressure rise. The second derivative is indicative of an acceleration of the combustion process and is, hence, fundamentally based. Furthermore, we have identified a new approach to determine the downward propagating flammable limits based on the combustion time, that is, the time that the gas actually burns in the vessel. Experimental data for methane and hydrogen show that the second derivative flammable limit criterion produces slightly conservative values for combustion in air. Visual inspection of the combustion during the tests showed that no visual combustion was observed at the second derivative criterion. For methane, the second derivative criterion resulted in a flammable range in air from 4.6 to 15.8% methane. For hydrogen these limits are 3.6–75.2%. We believe that this method will provide a much more fundamentally based method to determine both the upper and lower flammable limits of upward flame propagation and also provide a means to determine the downward propagation limits in a spherical combustion vessel. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009     

关井套压为零时安全问题探讨

当溢流关井后,在关井立压、套压均为零的情况下该如何处理,从实际案例出发,打破直接敞口循环排污这一思维定势,从气侵的特性着手,在关井套压为零条件下提出值得进一步分析检查的不安全因素和比较稳妥的做法,以达到更早地控制溢流、降低溢流量和减少压井作业难度的目的。     

Eating at the limits: Barriers to the emergence of social enterprise initiatives in the Australian emergency food relief sector

This article explores the absence of social enterprise responses to food insecurity in Australia. Continued growth in demand from chronically food insecure consumers and criticism of the dominant food bank model of gifted food support has led to the development of ‘community supermarkets’ that charge consumers for donated food in countries including Canada, the United Kingdom, France and Italy, but not in Australia. This research investigates barriers to the development of community supermarkets in Australia through in-depth interviews with senior staff within seven organizations involved in the food relief supply chain, as well as a pilot survey of 38 food insecure consumers. The results of this research are analyzed through the lens of ‘voluntary failure’ theory and highlight systemic barriers to the reach of social enterprise as a mechanism for addressing food insecurity.     

自重湿陷性黄土场地桩基持力层选择的探讨

通过国家重点工程建设项目-- 宁夏扶贫扬黄灌溉工程-固海扩灌工程,自重湿陷性黄土场地桩基勘察设计,提出大厚度自重湿陷性黄土场地桩基持力层的选择参考,通过现场预浸水大直径桩基载荷试验成果,为宁夏扶贫扬黄灌溉工程(固海扩灌)大厚度自重湿陷性黄土场地建筑物桩基设计提供了充分证据,缩短了该建设项目的工期,节省了大量建设费用.     

对介乎毛石与块石之间的砌石体容许压应力研究--对即将颁发的《砌石坝设计规范》主要成果的阐述

《浆砌石坝设计规范》(SL25-91)中将砌石体种类按毛石、块石、粗料石三种类别分别给予容许压应力值,但在实际工作中经常碰到介乎毛石、块石之间的砌石体种类,这种砌石体种类的容许压应力无章可循,给设计工作者带来许多不便,给工程造成不必要的损失。本文根据已有的试验资料经分析计算,给出了介乎毛石、块石之间的砌石体容许压应力值,该成果已被写入将要颁发的《砌石坝设计规范》之内。     

Assessing the effectiveness of a technical assistance program: The case of maize seed relief to vulnerable households in Zimbabwe

The recent economic downturn in Zimbabwe impoverished the majority of households. To assist vulnerable rural households improve their food security, the British Department for International Development implemented a seed relief program from 2003/2004 to 2005/2006 that emphasized recycling of maize open pollinated varieties (OPV). Using data collected from 597 households in six districts in 2006, this study assesses the effectiveness of the program in terms of its targeting of beneficiaries, the flow of information from participating NGOs to beneficiaries on the need to recycle the seeds, and the level of recycling done at the end of the program. The empirical results suggest that the targeting method participating NGOs use inadvertently excludes relatively vulnerable households while including large proportions of relatively well-endowed households in the program. The choice of varieties to distribute is guided more by the ecological adaptability of available commercial seeds and less by preferences of beneficiaries. Notwithstanding the fact that seed selection information is critical in encouraging beneficiaries to recycle distributed seed, not all of them received it. In conclusion, it may be stated that the program undoubtedly contributed to increased food productivity by vulnerable households but its overall effectiveness could have been enhanced through (i) the involvement of the beneficiaries in the choice of types of seed to be distributed, (ii) better targeting of beneficiaries, and (iii) improved information flow between NGOs and beneficiaries.     

自励恒压发电机组上网问题分析

本文针对双绕组电抗分流自励恒压发电机并列并网难及有、无功负荷分配不均等问题进行分析并对问题提出解决方案，适合广大农村28～500kw运行的小水电站参考。     

钢护筒嵌岩桩基联合受力响应特性试验研究

为了掌握钢护筒桩基础的受力特性与破坏机理,提高工程结构的安全性,以某内河直立码头项目为研究对象,开展了1:20的室内钢护筒嵌岩桩模型试验,分别对普通预制桩和钢护筒预制桩进行了嵌岩竖向承载试验和水平承载试验,对比分析了有钢护筒和没有钢护筒的条件下,桩体嵌岩深度对桩基承载性能的影响.分析结果表明,由于钢-岩土界面的咬合力较...     

析因实验设计与分析中的折扣系数及其应用——TAGUCHI方法研究

本文通过介绍在自动调节系统中常用的 TAGUCHI 最优校正法,引入折扣系数的概念;然后论述了在实验数据的方差分析中如何利用折扣系数的概念对最佳条件下响应的均值进行予测,并用两个例题分别说明折扣系数法在完全析因实验和分析因实验设计中的具体应用;最后是几点评论和补充说明。     

Excel在水利工程压力钢管制造工艺中的应用

介绍了Excel在水利工程项目压力钢管正圆锥体和加强圈的号料、展开及放样工艺中的应用。利用Excel系统的程序功能进行水利工程技术工艺计算,其具有宜推广、实用性强的特点,可极大的提高技术工艺的效率和准确性。     

响水电站高压埋管失稳破坏一些现象的探讨

响水水电站地下埋管失稳破坏给工程造成了重大的经济损失,引起了业界同行的广泛关注.作者就现场观察到的现象经分析,提出了造成该高压埋管失稳破坏的几种原因.     

工信部长：继续实施鼓励消费政策

工信部部长李毅中日前表示，目前，我国出口形势依然严峻，短期不可能恢复。他强调，经济增长要建立在扩大内需特别是扩大消费的基础上。     

Effect of operating conditions on pressure drop in a pulse-jet cleaned fabric filter

Tests were conducted to determine the effect of operating conditions on pressure drop in a pulse-jet cleaned fabric filter. A three-bag, pilot-scale filter was used. Polyester bags with ptfe-laminated surface and untreated surface collected fly ash and limestone dust at 30, 120, and 480 seconds between cleaning pulses to each bag. Tests were conducted using off-line and on-line cleaning. Results were compared to predictions of theoretical models. The models should be used only when sufficient dust is on the fabric to cause model parameters to remain constant.     

俯采面瓦斯负压排放

某煤矿属于高瓦斯矿井,瓦斯治理成为能否实现正常生产和保证矿井安全的关键。煤矿采用了上隅角及回风巷瓦斯超限治理方法,俯采面瓦斯负压排放办法,提出改进治理老塘瓦斯的几点建议。     

导压管路的安装对天然气流量测量的影响及对策

在天然气贸易计量过程中,任何失误或疏忽都可能引起流量测试数据的失真,从而导致不必要的管理纷争或利益损失.针对流量测试现场的实际情况,就流量测量过程中信号传输环节的现状、问题进行了分析,并由此提出了相应的解决措施.     

The response strategies of incumbent mobile network operators on the disruptive potential of public W-LAN in Germany

This paper examines how three incumbent mobile network operators (MNOs) in Germany responded in terms of their strategy to the emergence of the wireless local area network (W-LAN) technology and how they interpreted this potentially disruptive technology in their own strategic context. Additionally, prior empirical results and forecasts on the limited disruptive potential of W-LAN for the German MNOs lacked persuasive firm-level evidence to distinguish the real reason for the presented observations and analysis. So far it was unclear whether the observations were caused by successful response strategies of incumbent MNOs or by the inherent limited disruptive potential of the W-LAN technology. For this purpose case studies of three major MNOs in Germany were performed to assess and compare their respective response strategies. Using the theoretical framework of disruptive technology, the results were evaluated in a cross-case analysis to study how these firms interpreted and reacted to the potential disruptiveness of W-LAN. The results indicate significant differences for the respective MNOs between their perception of W-LAN as a potential disruptive technology, their strategic development processes inside the organisation to understand the potential impact of W-LAN on their respective business model, and to enforce an appropriate response strategy and structural implementation. This incumbent heterogeneity depends primarily on their idiosyncratic strategic and structural context. These findings reveal that the incumbent MNOs in Germany were aware of the disruptive technology concept but did not react in a theory-conform way. However, since W-LAN had a sustaining impact on the MNOs and their response strategies followed sustaining reaction patterns, earlier studies, which show a limited disruptive potential of W-LAN for the German MNOs, are supported.     

台阶级数对加筋土挡墙地震动力响应影响研究

为了优化加筋土挡墙的结构设计,研究了台阶级数对加筋土挡墙抗震性能的影响程度。基于Flac3D软件建立了加筋土挡墙数值模型,探讨了不同地震峰值加速度(peak ground acceleration,PGA)下不同台阶级数加筋土挡墙的侧向位移、竖向沉降、加速度响应和水平土压力的变化规律。结果表明：4 m/s²峰值加速度下,增加台阶级数,侧向位移减小了61.9%,竖向沉降减小了20.5%;PGA放大系数随着台阶级数的增加而增大,其中加筋区PGA放大系数略大于面板处PGA放大系数;1级加筋土挡墙最大水平土压力位于墙脚处,2,3级加筋土挡墙最大水平土压力位于台阶分级处;水平土压力在台阶分级处大于规范计算值。增加台阶级数能够提升加筋土挡墙的抗震性能,可为实际工程中加筋土挡墙的分级设计提供理论参考。