双无级调参顶驱同步抽油机理论研究

针对常规抽油机的缺陷,研制了一种新型顶驱同步抽油机,该抽油机采用永磁同步电机为动力,直接驱动主动轴,带动扁平皮带或同步带以提升井口载荷作上下往复运动;无减速和机械换向装置,采用变频电源和先进的控制理论和技术、精确的位移监测系统,冲程、冲次全部实现无级可调,运行曲线平滑,机杆泵的受力状况得到明显改善;对油井的产能和油品性质适用范围广,系统效率高.由于整机采用塔架结构,所以冲程长度的增加只需增加机架高度,而不需要改变其它部件,整机重量轻,结构简单,是现有抽油机的理想替代产品,具有很好的推广应用前景.     

Women in Cybersecurity: A Study of Career Advancement

Although cybersecurity is considered a critical area of information technology, women continue to be underrepresented among its ranks. This study, which is the first of female cybersecurity professionals, examines the skills women need to succeed in the industry, as well as the nature of the barriers and challenges they face at all points in their careers. Using face-to-face interviews and paper-based questionnaires, the study explored the views of high-ranking female cybersecurity officers and gained insights into how the needs of women might better be addressed, whether they're starting out in the educational system or advancing to the board rooms of major corporations. As cybersecurity provides an increasing number of IT jobs and becomes central to managerial operations within companies, women's advancement to executive and managerial positions will be important both for gender equity and to meet the needs of the market.     

A Nonspurious 3-D Vector Discontinuous Galerkin Finite-Element Time-Domain Method

We propose a nonspurious vector discontinuous Galerkin finite-element time-domain (DG-FETD) method for 3-D electromagnetic simulation. To facilitate the implementation of numerical fluxes for domain decomposition, we construct the DG-FETD scheme based on the first-order Maxwell's equations with variables ${bf E}$ and ${bf H}$. The LT/QN and the CT/LN edge elements are employed to represent ${bf E}$ and ${bf H}$, respectively (or vice versa), to suppress spurious modes, and the Riemann solver is utilized as the numerical flux to correct fields on the interfaces between adjacent subdomains. Numerical experiments show the nonspurious property of the proposed method.      

制氢转化炉运行问题分析和对策

中国石油化工股份有限公司洛阳分公司40 dam3/h制氢装置自开工以来,转化炉陆续出现了低温板式换热器腐蚀窜漏;烟道堵塞导致排烟温度和炉膛负压居高不下;低负荷时氧体积分数在8％以上;转化炉热效率在85％以下;出口温度达不到设计值;管支吊系统配重脱落等问题.分析认为,燃料气管网系统硫含量超标;预热器预防露点腐蚀措施不完善;集气管的恒力弹簧支吊架没有调整平衡;滑轮配重系统固定和设计制造质量不合格等是主要原因.采取了在低温预热器入口增设翅片管式前置预热器;重新设计低温板式换热器;更换板厚为1.5 mm的铸铁板式换热器;更换转化炉管上下保温箱衬里等措施后,转化炉热效率提升至89％,运行状况有了很大改善.     

Performance study on a WDM packet switch with limited-rangewavelength converters

We consider a slotted WDM packet switch with limited-range wavelength converters. The performance of this switch is studied using simulations with various types of data traffic. Results show that the slotted WDM packet switch with a small range of wavelength conversion capability can achieve a performance close to that of a switch with the full range of wavelength conversion capability     

The Role of a Natural Language Conversational Interface in Online Sales: A Case Study

This paper describes the evaluation of a natural language dialog-based navigation system (HappyAssistant) that helps users access e-commerce sites to find relevant information about products and services. The prototype system leverages technologies in natural language processing and human-computer interaction to create a faster and more intuitive way of interacting with websites, especially for less experienced users. The result of a comparative study shows that users prefer the natural language-enabled navigation two to one over the menu driven navigation. In addition, the study confirmed the efficiency of using natural language dialog in terms of the number of clicks and the amount of time required to obtain the relevant information. In the case study, as compared to the menu driven system, the average number of clicks used in the natural language system was reduced by 63.2% and the average time was reduced by 33.3%.     

Imprinted polymers for water purification

Imprinting polymerization is used to make resins with a high capacity for cadmium ions for wastewater treatment. A random copolymer of methacrylate and methacrylamide was found to be most effective, especially when the porosity of the resin is increased. Complete removal for up to 80 ppm of cadmium with only 50 mg of resin was demonstrated with the imprinted resins, but not the nonimprinted reference samples. This shows that imprinting polymerization improves the capacity of the resin in the uptake of cadmium ions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

丁烷溶剂脱沥青工艺的优化及应用

通过探索改进,对丁烷溶剂脱沥青工艺的抽提操作参数、超临界回收压力、装置流程、产品方案等进行了优化,使生产出的产品满足了质量要求,同时降低了装置的生产能耗。     

Robust control of switch-mode rectifier considering nonlinear behaviour

This work presents the disturbance observer-based robust current and voltage controls for a digital signal processor (DSP)-based boost-type switch-mode rectifier (SMR) considering nonlinear behaviour. First, a robust current control scheme is developed to let the SMR inductor current waveform closely track its command around zero-crossing points, and hence the SMR possesses improved line drawn power quality. Then a robust voltage two-degrees-of-freedom control (2DOFC) scheme and its systematic design approach are proposed. In determining the power circuit components and the key parameters of the proposed robust control schemes, the compromise between the desired performance and the nonlinear behaviours is considered. Specifically, the adaptation of voltage robust compensation control is made according to the observed nonlinear phenomena. Experimental results confirm that robust and good voltage tracking and regulation responses are obtained by the developed SMR. Furthermore, the developed SMR is successfully applied to serve as a front-end converter of a switched reluctance motor drive, and its effectiveness in vibration reduction and power quality improvement is demonstrated experimentally