云南某磷肥厂球磨机钢球配比的优化

针对云南某磷肥厂因钢球配比不合理、大球过多而造成的磨矿细度不高,不能很好地适应磷酸生产要求的问题,分析了入磨矿石的粒度组成.根据矿石的粒度组成采用昆明理工大学段希祥教授的精确化装补球方法,提出了一套针对该磷肥厂球磨机的精确化装球方案,同时提出了一个偏大方案和一个偏小方案,并和现厂的装球方案进行对比.针对四种装球方案进行了实验室扩大试验,研究结果表明:最佳装球方案为精确化装球方案,该方案与现厂的装球方案相比,可以使球磨机的生产能力提高14.44%;根据新方案的粒度特性曲线给出了补加钢球的方案,按此方案补加钢球可以使球磨机中的球荷组成始终保持近似于推荐的初装球组成.     

浅谈下坂地水电站水轮机的安装

1 水轮机的技术特性 以新疆下坂地水利枢纽工程下坂地水电站安装水轮机的实际情况为例子,进一步说明水轮机的安装情况和工程操作,水电站的具体情况是,下坂地水电站有3台150MW混流式水轮机,水轮机为立式,含有微机调速器,转轮为上拆式,底环及尾水锥管为埋入式,新疆下坂地水利枢纽工程混流式水电站水轮机主要由转轮、导水机构、主轴密封、水导轴承、受油器等构成.水轮机为轴流转桨式,钢里衬混凝土蜗壳,T型断面,弯肘型尾水管,通过水、发大轴与发电机直接连接.     

Influence of photoperiod on carbon dioxide and methane emissions from two pilot-scale stabilization ponds

Greenhouse gas (GHG) emissions (CO(2), CH(4)) from pilot-scale algal and duckweed-based ponds (ABP and DBP) were measured using the static chamber methodology. Daylight and nocturnal variations of GHG and wastewater characteristics (e.g. chemical oxygen demand (COD), pH) were determined via sampling campaigns during midday (12:30-15:30) and midnight (00:30-03:30) periods. The results showed that under daylight conditions in ABP median emissions were -232 mg CO(2) m(-2) d(-1) and 9.9 mg CH(4) m(-2) d(-1), and in DBP median emissions were -1,654.5 mg CO(2) m(-2) d(-1) and 71.4 mg CH(4) m(-2) d(-1), respectively. During nocturnal conditions ABP median emissions were 3,949.9 mg CO(2) m(-2) d(-1), 12.7 mg CH(4) m(-2) d(-1), and DBP median emissions were 5,116 mg CO(2) m(-2) d(-1), 195.2 mg CH(4) m(-2) d(-1), respectively. Once data measured during daylight were averaged together with nocturnal data the median emissions for ABP were 1,566.8 mg CO(2) m(-2) d(-1) and 72.1 mg CH(4) m(-2) d(-1), whilst for DBP they were 3,016.9 mg CO(2) m(-2) d(-) and 178.9 mg CH(4) m(-2) d(-1), respectively. These figures suggest that there were significant differences between CO(2) emissions measured during daylight and nocturnal periods (p < 0.05). This shows a sink-like behaviour for both ABP and DBP in the presence of solar light, which indicates the influence of photosynthesis in CO(2) emissions. On the other hand, the fluxes of CH(4) indicated that DBP and ABP behave as net sources of CH(4) during day and night, although higher emissions were observed from DBP. Overall, according to the compound average (daylight and nocturnal emissions) both ABP and DBP systems might be considered as net sources of GHG.     

Highly discriminative statistical features for email classification

This paper reports on email classification and filtering, more specifically on spam versus ham and phishing versus spam classification, based on content features. We test the validity of several novel statistical feature extraction methods. The methods rely on dimensionality reduction in order to retain the most informative and discriminative features. We successfully test our methods under two schemas. The first one is a classic classification scenario using a 10-fold cross-validation technique for several corpora, including four ground truth standard corpora: Ling-Spam, SpamAssassin, PU1, and a subset of the TREC 2007 spam corpus, and one proprietary corpus. In the second schema, we test the anticipatory properties of our extracted features and classification models with two proprietary datasets, formed by phishing and spam emails sorted by date, and with the public TREC 2007 spam corpus. The contributions of our work are an exhaustive comparison of several feature selection and extraction methods in the frame of email classification on different benchmarking corpora, and the evidence that especially the technique of biased discriminant analysis offers better discriminative features for the classification, gives stable classification results notwithstanding the amount of features chosen, and robustly retains their discriminative value over time and data setups. These findings are especially useful in a commercial setting, where short profile rules are built based on a limited number of features for filtering emails.     

A collaborative platform for cognitive decision making in the Knowledge Society

Two key aspects of the Knowledge Society are the interconnection between the actors involved in the decision making processes and the importance of the human factor, particularly the citizen’s continuous learning and education. This paper presents a new module devoted to knowledge extraction and diffusion that has been incorporated into a previously developed decision making tool concerning the Internet and related with the multicriteria selection of a discrete number of alternatives (PRIOR-Web). Quantitative and qualitative procedures using data and text mining methods have been employed in the extraction of knowledge. Graphical visualisation tools have been incorporated in the diffusion stage of the methodological approach suggested when dealing with decision making in the Knowledge Society. The resulting collaborative platform is being used as the methodological support for the cognitive democracy known as e-cognocracy.     

Asymptotic synchronization of the Colpitts oscillator

In this paper we deal with the observer-based asymptotic synchronization problem for a class of chaotic oscillators. Some results based on a differential algebraic approach are used in order to determine the algebraic observability of unknown variables. The strategy consists of proposing a slave system (observer) which tends to follow asymptotically the master system. The methodology is tested in the real-time asymptotic synchronization of the Colpitts oscillator by means of a proportional reduced order observer (PROO) of free-model type.     

F-MPJ: scalable Java message-passing communications on parallel systems

This paper presents F-MPJ (Fast MPJ), a scalable and efficient Message-Passing in Java (MPJ) communication middleware for parallel computing. The increasing interest in Java as the programming language of the multi-core era demands scalable performance on hybrid architectures (with both shared and distributed memory spaces). However, current Java communication middleware lacks efficient communication support. F-MPJ boosts this situation by: (1) providing efficient non-blocking communication, which allows communication overlapping and thus scalable performance; (2) taking advantage of shared memory systems and high-performance networks through the use of our high-performance Java sockets implementation (named JFS, Java Fast Sockets); (3) avoiding the use of communication buffers; and (4) optimizing MPJ collective primitives. Thus, F-MPJ significantly improves the scalability of current MPJ implementations. A performance evaluation on an InfiniBand multi-core cluster has shown that F-MPJ communication primitives outperform representative MPJ libraries up to 60 times. Furthermore, the use of F-MPJ in communication-intensive MPJ codes has increased their performance up to seven times.     

创新型经济发展对会计人才培养的影响

通过对2l世纪区域经济发展模式的调查,阐述了创新型经济的概念和特征,分析了创新型经济对企业会计业务的影响,研究了创新型经济对会计人员提出的新要求,从而提出了会计人才培养的改革设想。     

闸后水流运动的SPH法数值模拟

在对光滑离子流体动力学(SPH)法的基本原理、核函数及控制方程离散格式、边界处理方法等进行介绍的基础上建立了数值水槽模型,成功模拟了闸门开启后水流的界面变形、界面破碎、气泡的生成及溃灭,以及涌浪的生成过程。结果表明SPH法能够捕捉到流体的飞溅及融合现象,适于模拟具有瞬时极大变形等水流运动。