3,4－二氨基乙二肟(DAG)的制备、晶体结构及热行为

通过乙二醛、盐酸羟胺在NaOH溶液中脱水反应,制备了3,4-二氨基乙二肟(DAG),并培养出DAG的单晶。利用X射线单晶衍射分析、元素分析和傅里叶变换红外光谱分析对其进行结构表征。测试结果表明:晶体属单斜晶系,空间群P21,晶胞参数:a=0.6763(8)nm,b=0.3578(4)nm,c=0.9658(12)nm,β=90.78(2),°V=0.2338(5)nm3,Z=2,Dc=1.678 g.cm-3,F(000)=124,μ(Mo Kα)=0.146 mm-1,最终R因子[I>2σ(I)]:R1=0.0403,wR2=0.1098,R因子(全部所有数据):R1=0.0422,wR2=0.1122。DAG分子呈平面构型,为反式结构,其晶体为黄色针状晶体,分子间存在三种氢键,形成三维空间网状结构,提高了分子的稳定性。用TG-DTG和DSC技术研究了DAG的热分解过程,在10℃.m in-1的升温条件下,其熔点为203.5℃,在209~212℃、212~240℃之间发生两步剧烈分解反应,至240℃完全分解。     

植物甾醇双甘酯油营养特性

该文阐述含植物甾醇以双甘酯为主要成分健康油的结构,营养特性,脂质代谢机理与食用安全性。     

基于STFT变换和DAGSVMs的电能质量扰动识别

提出了一种基于短时傅里叶变换和DAG(Directed Acyclic Graph)支持向量机的电能质量扰动检测和识别方法.将扰动信号通过Blackman窗短时傅里叶变换,得出时域最大幅值向量,然后把它作为特征向量输入到DAG支持向量机来实现电能质量扰动类型的识别.其中,时域最大幅值向量不仅能反映各种扰动的特征,还能显示电压突升、电压暂降、电压中断和暂态振荡等扰动的发生时刻和持续时间.仿真测试表明,该方法能有效识别各种电能质量扰动,而且识别正确率高,训练时间短,实时性能较好.     

异构网络化汽车电子系统中多DAG离线任务调度

公平性和通信开销已成为影响调度性能的主要瓶颈,首先在任务优先级排序阶段,提出基于通信开销权值的轮转调度的公平排序标准;在处理器选择阶段,提出在插入法的基础上将任务分配到具有最小选择值的选择标准;综合上述2个阶段,提出以降低调度长度和减少通信开销为目标的多DAG离线公平任务调度(MDOFTS, multiple DAGs off-line and fairness task scheduling)算法。异构网络化汽车电子系统是一个典型的混合关键级嵌入式系统,既要确保实时性又要降低调度长度,提出了以满足安全关键DAG的多DAG离线优先级任务调度(MDOPTS, multiple DAGs off-line and Priority task scheduling)算法。综合MDOFTS和MDOPTS,提出多DAG离线自适应任务调度(MDOATS, multiple DAGs off-line and adaptive task scheduling)算法,在满足实时性的基础上提高调度性能。实例分析和实验结果表明,提出的算法在调度长度、通信开销、不公平性、最差响应时间和实时性上都优于其他算法。     

Optimization of Reaction Conditions in the Enzymatic Interesterification of Soybean Oil and Fully Hydrogenated Soybean Oil to Produce Plastic Fats

Semisolid fats obtained from oils and fats through enzymatic interesterification have interesting applications. The effect of certain reaction parameters (enzyme concentration, moisture content, reaction time, substrate ratio, temperature, and agitation level) over the enzymatic interesterification of fully hydrogenated soybean oil (FHSO) and refined soybean oil (SO) using two immobilized enzyme types (Lipozyme RM IM and Lipozyme TL IM), was studied with a fractional factorial design (FFD). The reaction products were analyzed with respect to melting point (mp), by-products content and triacylglycerols (TAG) composition. It was found that substrate ratio, reaction time, and their interaction presented the most significant contributions to mp, varying this from 43.4 to 61.5 °C. The highest contributions to by-product content were presented by time and its interaction with the amount of molecular sieves, mainly for Lipozyme TL IM. Through the models obtained, theoretical conditions to achieve minimal by-product generation and mp were found, being 5.0 % (w/w_subst.) of any of both lipases, 24 h, 70:30 (oil:fat,  % w/w), 65 °C, 230 rpm, and absence of molecular sieves. Regression models for TAG groups as a function of significant factors and interactions were constructed, offering useful information to establish the reaction conditions for obtaining a product with a target mp or chemical composition.     

云计算环境下多有向无环图工作流的节能调度算法

针对多有向无环图(DAG)工作流节能调度算法中存在的节能效果不佳、适用范围较窄和无法兼顾性能优化等问题,提出了一种新的多DAG工作流节能调度方法--MREO。MREO在对计算密集型和通信密集型任务特点进行分析的基础上,通过整合独立任务,减少了处理器的数量,并利用回溯和分支限界算法对任务整合路径进行动态的优化选择,有效降低了整合算法的复杂度。实验结果证明,MREO在保证多DAG工作流性能的前提下,能够有效降低系统的计算和通信能量开销,获得了良好的节能效果。     

一种基因本体术语间的语义相似度计算方法

计算基因本体中的术语的语义相似度是基因本体的一个重要应用。基于信息量和基于距离的语义相似度计算方法都只从各自的角度计算术语间语义相似度。提出了基于基因本体中术语所在有向无环图的计算方法。该方法既考虑了术语的祖先对其的信息量的影响,又考虑了术语所在的位置以及术语间的语义联系类型。实验结果表明该方法有较高的准确度。     

An Optimized Labeling Scheme for Reachability Queries

Answering reachability queries is one of the fundamental graph operations. Existing approaches either accelerate index construction by constructing an index that covers only partial reachability relationship, which may result in performing cost traversing operation when answering a query; or accelerate query answering by constructing an index covering the complete reachability relationship, which may be inefficient due to comparing the complete node labels. We propose a novel labeling scheme, which covers the complete reachability relationship, to accelerate reachability queries processing. The idea is to decompose the given directed acyclic graph (DAG) G into two subgraphs, G1 and G2. For G1, we propose to use topological labels consisting of two integers to answer all reachability queries. For G2, we construct 2-hop labels as existing methods do to answer queries that cannot be answered by topological labels. The benefits of our method lie in two aspects. On one hand, our method does not need to perform the cost traversing operation when answering queries. On the other hand, our method can quickly answer most queries in constant time without comparing the whole node labels. We confirm the efficiency of our approaches by extensive experimental studies using 20 real datasets.     

基于Web的网格入口软件研究与实现

通过分析网格的使用模式,设计实现了网格入口软件WebGrid。WebGrid的研究与实现围绕网格监控和任务调度展开,采用了基于遗传算法的任务调度算法。该算法采用资源-任务的间接编码方式,通过DAG图获取子任务的层次关系,并将子任务按照层次深度排序,解决了种群的非法问题。在单一资源上采用短任务优先和父结点优先两个原则来安排子任务的执行次序,避免出现任务堵塞的现象。