Agroecological analysis and economic benefit of organic resources and fertiliser in till and no-till sorghum production after a 6-year fallow in semi-arid West Africa

A field experiment was conducted in Gampela (Burkina Faso) in 2000 and 2001 to assess the impact of organic and mineral sources of nutrients and combinations thereof in optimising crop production in till and no-till systems and to assess the economic benefit of these options. The study showed that under conditions of rainfall deficiency, the use of a single organic resource at an equivalent dose of 40 kg N ha⁻¹ better secured crop yield than the application of an equivalent amount as urea-N, while a combination of organic resources and fertiliser was better in increasing crop yield than the application of the same N amount in the form of urea. In a year of rainfall deficiency, a mix of organic resources and fertiliser in both till and no-till systems increased crop water use efficiency, with the result that the farmer was able to purchase only half of the normal quantity of N fertiliser to obtain a higher yield that he would have done when all of the N was supplied in the form of urea. Under conditions where soil N is deficient, an economic benefit was achieved when urea was combined with easily decomposable organic material (e.g. sheep dung); mixing the urea at a dose of 40 kg N ha⁻¹ with maize straw was not sufficient in alleviating the negative interaction due to the enhanced N immobilisation. The results demonstrate that the use of N fertiliser alone was risky and that a higher yield, with the accompanying economic benefit, was scarcely achieved under the prevailing rainfall conditions. The application of soil and water conservation measures can contribute greatly to increasing the economic benefit of mineral, organic or combined organic and mineral-derived nutrient application under semi-arid conditions.     

相控阵雷达天线阵面记录回放系统

相控阵雷达广泛应用,其天线阵面对记录回放系统的数据速率要求提升。针对两种传统记录回放系统架构的不足,结合其优点,设计并实现了一种新型的基于FPGA的记录回放系统。该系统设计为板卡的形式,FPGA实现对硬盘的读写操作,采用自定义的文件系统对数据进行管理。经过测试,系统记录速度可以达到292 MB/s,回放速率为340 MB/s。实验结果表明,该记录回放系统性能稳定,通用性好,存储速率满足要求。     

A method for transformation of engineering bill of materials to maintenance bill of materials

In order to solve the transformation problem of Bill of Materials (BOM) from engineering BOM to maintenance BOM for Maintenance, Repair and Overhaul (MRO) systems, a formal transformation model of BOM view is proposed. In this model, the intermediate component, inherited component, virtual component are defined in the specific maintenance management domain, and the transformation process from engineering BOM to maintenance BOM is discussed through feature recognition methods and rules. The proposed transformation model has been developed and deployed in an MRO system for a steel manufacturing enterprise.     

自密封阀在氨汽提尿素装置中的应用与维修

介绍自密封阀的密封原理及其在氨汽提尿素装置中的应用,对其长期运行中出现的泄漏及泄漏原因进行分析,根据不同的泄漏方式分别提出了现场维修的方法.     

Detecting stable locality-aware predicates

In a large-scale locality-driven network such as in modular robotics and wireless sensor networks, knowing the state of a local area is sometimes necessary due to either interactions being local and driven by neighborhood proximity or the users being interested in the state of a certain region. We define locality-aware predicates (LAP) that aim at detecting a predicate within a specified area. We model the area of interest as the set of processes that are within a breadth-first search tree (BFST) of height k$k$ rooted at the initiator process. Although a locality-aware predicate specifies a predicate only within a local area, observing the area consistently requires considering the entire system in a consistent manner. This raises the challenge of making the complexities of the corresponding predicate detection algorithms scale-free, i.e., independent of the size of the system. Since all existing algorithms for getting a consistent view of the system require either a global snapshot of the entire system or vector clocks of the size of the system, a new solution is needed. We focus on stable LAP, which are those LAP that remain true once they become true. We propose a scale-free algorithm to detect stable LAP within a k$k$-height BFST. Our algorithm can detect both stable conjunctive LAP and stable relational LAP. In the process of designing our algorithm, we also propose the first distributed algorithm for building a BFST within an area of interest in a graph, and the first distributed algorithm for recording a consistent sub-cut within the area of interest. This paper demonstrates that LAPs are a natural fit for detecting distributed properties in large-scale distributed systems, and stable LAPs can be practically detected at low cost.     

专家系统在注塑模结构设计中的应用

介绍了知识库与推理机分离专家系统的原理及程序实现方法,并给出了专家系统的应用实例。     

PerContRep: a practical reputation system for pervasive content services

Social network has extended its popularity from the Internet to mobile domain. Personal mobile devices can be self-organized and communicate with each other for instant social activities at any time and in any places to achieve pervasive social networking (PSN). In such a network, various content information flows. To which extent should mobile users trust it, whilst user privacy can also be preserved? Existing work has not yet seriously considered trust and reputation management, although trust plays an important role in PSN. In this paper, we propose PerContRep, a practical reputation system for pervasive content services that can assist trustworthy content selection and consumption in a pervasive manner. We develop a hybrid trust and reputation management model to evaluate node recommendation trust and content reputation in the context of frequent change of node pseudonyms. Simulations show the advantages of PerContRep in assisting user decisions and its effectiveness with regard to unfair rating attack, collaborative unfair rating attack, on-off attack and conflict behavior attack. A prototype system achieves positive user feedback on its usability and social acceptance.     

球形氧化锆的湿法制备过程研究

以氯氧化锆和碳酸氢铵为原料，采用连续反应沉淀法制备了微米级球形氧化锆前驱体，此前驱体在500℃下于空气气氛中煅烧2h得到球形氧化锆粉体。探讨了锆盐溶液浓度、加料速度、pH、反应时间对粉体颗粒粒径大小及其分布的影响。经SEN，XRD，TG—DSC和激光粒度测试仪分析，结果表明在最佳工艺条件下制备的氧化锆前驱体颗粒呈球形，分散性好，粒径分布在8—18μm。     

Use of cascade reduction potential for selective precipitation of Au,Cu, and Pb in hydrochloric acid solution

Optimization of reduction potential for electroseparation was studied for the recovery of gold, copper, and lead from acidic solution. A linear sweep voltammetric method enabled us to determine characteristic reduction potentials for each metal and the kinetics of the metal deposition indicated by current-voltage curves. In order to precipitate the metal species sequentially, reduction potentials were examined for the individual and mixed solutions of Au(III), Cu(II), and Pb(II). The three metals were reasonably well isolated from the mixed solutions such as Cu(II)/ Pb(II) and Au(III)/Cu(II)/Pb(II) in the order of the corresponding reduction potentials, in particular, the mass transfer controlled reduction potentials, obtained from linear sweep voltammetry (LSV) measurement.     

黄磷的物理法脱砷新方法探索研究

针对我省黄磷精制现状,研究一种黄磷除砷新方法。利用高压静电场对工业黄磷进行处理,结果显示:在电场的作用下能分离除去砷,经三级处理脱砷率可达90%以上,黄磷回收率在99.9%以上。简要介绍了此处理方法的原理及工艺。