Reactive energy measurement using frequency controlled analog-to-pulse-rate converter

Contents This paper analyzes a problem of phase shifting and deseribes a novel method for electronic reactive energy measurement. The proposed measurement structure, composed of an integrator as a phase shifting circuit and a frequency controlled analog-to-pulse-rate converter, provides for the measurement completely in accordance with IEC definition of reactive energy, which is performed with simple but high performance metering device.

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Die Blindverbrauchsmessung anhand eines netzsynchronisierten Analog-Frequenz-Wandlers

Übersicht In diesem Artikel wird das Problem der Phasenverschiebung analysiert und eine neue Meßmethode für elektronische Blindverbrauschsmessung aufgezeigt. Die vorgeschlagene Strucktur, bestehend aus einem Integrator als Phasenschieber und netzkontrolliertem Analog-Frequenz-Wandler, ermöglicht die Verwirklichung eines einfachen aber präzisen Elektrizitätszählers zur Messung der Blindenergie, dessen Arbeitsprinzip mit den IEC Empfehlungen vollkommen übereinstimmt.

     

Robust adaptive control of robotic manipulators without the regressor matrix

A new adaptive controller is presented here for rigid-body robotic manipulators. It is stable and robust with respect to a class of external disturbances. The robustness of the adaptive controller is established without the ‘slow-varying’ assumption and the computationally demanding regressor matrix. The control law consists of a non-adaptive PD control part and an adaptive control part. It uses two adaptive matrices to compensate two uniformly bounded coefficient matrices derived from the original dynamics. A α σ|q?|-modified adaptive law is designed to adjust the adaptive matrices. A Lyapunov-type stability analysis indicates that the closed-loop system is uniformly ultimately bounded. The tracking error and compensation error will eventually converge into a closed region, which can be made arbitrarily small by adjusting the controller parameters. Simulation results are included to demonstrate the performance of the proposed controller.     

Fluidised pellet bed bioreactor: a promising technology for onsite wastewater treatment and reuse.

A pilot-scale fluidised pellet bed (FPB) bioreactor, which combines chemical coagulation, biological degradation, particle pelletisation and separation in one unit, was applied for onsite wastewater treatment and reuse. As a result of rational use of inorganic coagulant and organic polymer and moderate mechanical agitation, spherical particles were generated in the upflow column and a well-fluidised bed was formed. With a continuous supply of dissolved oxygen through a recycling loop, an aerobic condition was kept in the bottom section of the FPB column. Under such conditions the pellets in the FPB column showed the following characteristics: (1) compact structure and high density; (2) rich in microorganisms; and (3) high MLSS and MLVSS concentrations. Therefore, the FPB bioreactor achieved more than 90% removal of SS, COD, BOD and TP from raw domestic wastewater within a total hydraulic retention time (HRT) of only about 30 minutes. It also showed nitrification and denitrification ability and the TN removal could be about 50% as the recycling ratio was increased to 1:1. The treated water quality is generally competitive with the secondary effluent from a conventional activated sludge process. With these advantages the FPB bioreactor is recommendable as a compact system for onsite wastewater treatment and reuse.     

用面向对象编程实现问题求解自动化

本文从面向对象方法基本原理和面向对象编程的技术特征出发，阐明所建应用软件系统中的对象，类及相应类层次结构和类组合结构，使系统具有很强的表现真空世界复杂系统结构的能力，系统通过消息传递在程序执行中实现对操作的调用机制，使之在面向用户问题选择和执行求解策略方面有很强的适应性，这一点对于强调人－机交互和解题协作的智能决策支持系统设计至关重要，文章给出了用Ｃ＋＋实现的模型对象系统及消息传递机制。     

强化管理提高特超稠油开发效果

河南稠油资源品位低,开采难度大,效益差。近几年,通过实践,逐渐摸索出一套适应开发需要的科学生产管理方法,明显地改善了稠油开发效果。以提高热效率为核心,形成了八大生产管理制度;深化油藏认识,使油藏-工艺-管理三者有机结合,充分利用了地层储热,提高了周期吞吐开发水平;以降粘、防砂、堵窜为重点,实现了地面-井筒-油层三位一体工艺配套,保证了油井正常生产。     

Software defect prediction model based on LASSO–SVM

Neural Computing and Applications - A software defect report is a bug in the software system that developers and users submit to the software defect library during software development and...     

低负荷维氏硬度法的负荷选择

本文按照维氏硬度测定的技术条件,将基本公式H_v=1854P/D~2加以变换,从而得到一些较为简单的数学关系式.利用这些关系式,可以对不同金属薄带材料,很容易计算出较合理的负荷大小,既能保证不被"打穿",也使视场内有一个适合观测的压痕图象.     

Site occupations and ordering behaviour of O phase in Ti2AlNb—based intermetallics

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Effect of supports on the redox performance of pyrite cinder in chemical looping combustion

Chemical looping combustion (CLC) is a clean and efficient flame-free combustion technology,which combust the fuels by lattice oxygen from a solid oxygen carrier with inherent CO2 capture.The develop-ment of oxygen carriers with low cost and high redox performance is crucial to the whole efficiency of CLC process.As the solid by-product from the sulfuric acid production,pyrite cinder presented excellent redox performance as an oxygen carrier in CLC process.The main components in pyrite cinder are Fe2O3,CaSO4,Al2O3 and SiO2 in which Fe2O3 is the active component to provide lattice oxygen.In order to sys-tematic investigate the functions of supports (CaSO4,Al2O3 and SiO2) in pyrite cinder,three oxygen car-riers (Fe2O3-CaSO4,Fe2O3-Al2O3 and Fe2O3-SiO2) were prepared and evaluated in this study.The results showed that Fe2O3-CaSO4 displayed high redox activity and cycling stability in the multiple redox cycles.However,both Fe2O3-Al2O3 and Fe2O3-SiO2 experienced serious deactivation during redox reactions.It indicated that the inert Fe-Si solid solution (Fe2SiO4) was formed in the spent Fe2O3-SiO2 sample,which decreased the oxygen carrying capacity of this sample.The XPS results showed that the oxygen species on the surface of Fe2O3-CaSO4 could be fully recovered after the 20 redox cycles.It can be concluded that CaSO4 is the key to the high redox activity and cycling stability of pyrite cinder.