钻井泥浆抑制剂JFT的实验研究

针对钻井过程中泥页岩的水化膨胀导致井壁不稳定和泥浆性能恶化这一严重问题 ,通过室内试验研制了一种阳离子型聚合物抑制剂———JFT ,并进行了性能评价。结果表明 ,该抑制剂具有好的水溶性、时间稳定性和热稳定性 ,其适应温度范围广 (在 30～ 95℃下不生成絮状沉淀 ) ,有效浓度为 1 %的JFT比 5 %KCl的抑制性好。     

Aspectualization of code clones—an algorithmic approach

System Modularity has positive effects on software maintainability, reusability, and understandability. One factor that can affect system modularity is code tangling due to code clones. Code tangling can have serious cross-cutting effects on the source code and thereby affect maintainability and reusability of the code. In this research we have developed an algorithmic approach to convert code clones to aspects in order to improve modularity and aid maintainability. Firstly, we use an existing code-clone detection tool to identify code clones in a source code. Secondly, we design algorithms to convert the code clones into aspects and do aspect composition with the original source code. Thirdly, we implement a prototype based on the algorithms. Fourthly, we carry out a performance analysis on the aspects composed source code and our analysis shows that the aspect composed code performs as well as the original code and even better in terms of execution times.     

Improved Randomized Online Scheduling of Intervals and Jobs

We study the online preemptive scheduling of intervals and jobs (with restarts). Each interval or job has an arrival time, a deadline, a length and a weight. The objective is to maximize the total weight of completed intervals or jobs. While the deterministic case for intervals was settled a long time ago, the randomized case remains open. In this paper we first give a 2-competitive randomized algorithm for the case of equal length intervals. The algorithm is barely random in the sense that it randomly chooses between two deterministic algorithms at the beginning and then sticks with it thereafter. Then we extend the algorithm to cover several other cases of interval scheduling including monotone instances, C-benevolent instances and D-benevolent instances, giving the same competitive ratio. These algorithms are surprisingly simple but have the best competitive ratio against all previous (fully or barely) randomized algorithms. Next we extend the idea to give a 3-competitive algorithm for equal length jobs. Finally, we prove a lower bound of 2 on the competitive ratio of all barely random algorithms that choose between two deterministic algorithms for scheduling equal length intervals (and hence jobs). A preliminary version of this paper appeared in Fung et al. (The 6th International Workshop on Approximation and Online Algorithmspp, vol. 5426, pp. 53–66, 2008).     

Echo state networks based predictive model of vinyl chloride monomer convention velocity optimized by artificial fish swarm algorithm

Conversion rate in the Polyvinylchloride (PVC) polymerizing process has a certain influence on the molecular weight of PVC, porosity, absorption rate of plasticizer, vinyl chloride monomer (VCM) residue and thermal stability. Therefore, a predictive model based on echo state networks (ESN) method optimized by the artificial fish swarm algorithm (AFSA) is proposed to predict the conversion velocity. Firstly, the hot balancing mechanisms of polymerizer and the influenced factors of convention rate of VCM are analyzed in details. Then the auxiliary variables of the predictive model kernel are selected by using the kernel principal component analysis method for reducing the model dimensionality. Thirdly, the structure parameters of the ESN are optimized by the AFSA to realize the nonlinear mapping between input and output variables of the discussed soft-sensor model. The artificial fish swarm behaviors, such as foraging, swarming, chasing, random, are introduced in details. Finally, simulation results show that the proposed model can significantly enhance the predictive accuracy and robustness of the technical index and satisfy the real-time control requirements of PVC polymerizing production process.     

Model-based test generation using extended symbolic grammars

A novel, model-based test case generation approach for validating reactive systems, especially those supporting richly structured data inputs and/or interactions, is presented. Given an executable system model and an extended symbolic grammar specifying plausible system inputs, the approach performs a model-based simulation to (i) ensure the consistency of the model with respect to the specified inputs, and (ii) generate corresponding test cases for validating the system. The model-based simulation produces a state transition diagram (STD) automatically justifying the model runtime behaviors within the test case coverage. The STD can further be transformed to produce an evolved symbolic grammar, which can then be used to incrementally generate a refined set of test cases. As a case study, we present a live sequence chart (LSC) model-based test generator, named LCT in short, for LSC simulation and consistency testing. The evolved symbolic grammar produced by the simulator can either be used to generate practical test cases for software testing, or be further refined by applying our model-based test generation approach again with additional test coverage criteria. We further show that LSCs can also be used to specify and test certain temporal system properties during the model simulation. Their satisfaction, reflected in the STD, can either be served as a directive for selective test generation, or a basis for further temporal property model checking.     

固定化微生物技术在废水处理中的应用

通过对固定化技术方法以及不同载体选择的介绍,分析评价了固定化微生物在废水处理中应用研究进展。认为固定化微生物是一种比一般生物处理法更为高效的方法,并讨论了它在含毒重金属离子废水、有机废水、难降解废水、含磷含氮废水中的应用。研究表明:固定化技术的应用前景十分广泛,但在从实验室阶段走向废水处理的实际应用阶段上还存在一些问题。     

Cell structure and dynamic properties of injection molded polypropylene foams

The cell structure and properties of branched and linear polypropylene (PP) foams containing organically modified nanoclay and maleic anhydride grafted polypropylene (PPMA) have been thoroughly investigated. X-ray diffraction (XRD) and melt rheometry were used to identify the structure and linear viscoelastic properties of the nanocomposites, as well as the effectiveness of two different compatibilizers. These nanocomposites were used in injection molding to investigate their foamability and the influence of experimental conditions such as chemical foaming agent concentration, shot size, back pressure, injection speed, as well as melt temperature and different injection methods on the resulting cell structure of the foams. Quite different results were obtained with the linear and the branched PP. While the foamability of the branched PP was intrinsically good, that of the linear one could largely be improved by modifying its rheological properties and favoring nucleation through the addition of nanoclay. The effect of cell structure on the dynamic mechanical properties of the foams was also investigated using dynamic mechanical analysis (DMA). POLYM. ENG. SCI., 47:1070–1081, 2007. © 2007 Society of Plastics Engineers     

尖晶石质浸入式水口内衬的研究

以77%的电熔尖晶石(粒度≤1mm和≤0.074mm)、20%的α-Al2O3(≤2μm)和3%的电熔镁砂(≤0.074mm)为原料,分别在1000℃、1200℃、1500℃保温3h的条件下,研究了SiO2微粉外加量(分别为0、0.5%、1.0%、1.5%)对尖晶石材料烧结性能的影响,并在1450℃的还原性气氛下进行了尖晶石内衬材料与铝碳本体材料的复合试验。研究结果表明:在不过多增加尖晶石材料高温液相量的情况下,SiO2微粉的外加量为1.0%较为适宜;在尖晶石试样中同时添加1%SiO2微粉和3%电熔镁砂细粉能很好地降低其烧结温度,而且其热膨胀率与铝碳材料的热膨胀率较为接近,而尖晶石材料与铝碳材料的复合试验结果也表明,内衬和本体材料结合完好,且无裂纹出现。     

我国高职教育借鉴德国职业教育模式的问题与改善

德国职业教育模式在我国发展和普及已经近30年了,为我国加快发展现代职业教育提供了借鉴。简析了德国职业教育模式在中国的发展现状,并指出了在实施中遇到的问题,提出了相关的解决方法和改善办法。