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DS-CDMA system outer loop power control and improvement for multi-service

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Journal of Systems Engineering and Electronics 2008年第3期19卷 453-460页

作者： Guan Mingxiang Guo Qing Li Xing School of Electronic and Information Technology Harbin Inst. of Technology Harbin 150001 P.R. China Huawei Technologies Co. Ltd Shenzhen 518057 P. R. China

When a new user accesses the CDMA system, the load will change drastically, and therefore, the advanced outer loop power control （OLPC） technology has to be adopted to enrich the target signal interference ratio （Silt） and improve the system performance. The existing problems about DS-CDMA outer loop power control for multi-service are introduced and the power control theoretical model is analyzed. System simulation is adopted on how to obtain the theoretical performance.and parameter optimization of the power control algorithm. The OLPC algorithm is improved and the performance.comparisons between the old algorithm and the improved algorithm are given. The results show good performance.of the improved OLPC algorithm and prove the validity of the improved method for multi-service.

关键词： DS-CDMA outer loop power control multi-service performance.

Study on fire-retardant nanocrystalline Mg-Al layered double hydroxides synthesized by microwavecrystallization method

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Science China Chemistry 2004年第6期47卷 488-498页

作者： ZHANG Zejiang1, XU Chenghua1, QIU Fali1, MEI Xiujuan2, LAN Bin2 & ZHANG Shuosheng2 1. Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China 2. Sichuan Fire Research Institute of Public Safety Ministry, Chengdu 611830, China Chengdu Institute of Organic Chemistry Chinese Academy of Sciences Chengdu China Sichuan Fire Research Institute of Public Safety Ministry Chengdu China

Nanocrystalline Mg-Al layered double hydroxides with the particle size being 10—40 nm were firstly prepared by the technology of the microwave-crystallization and the vari- able-speed addition of the alkali. The obtained samples were characterized by TEM and XRD. The roles of the microwave and addition rate of the alkali were also discussed in the present work. The thermal decomposition activation energy of the nano-LDHs was calculated according to their TG, DTG and DSC curves by the Ozawa method. The results showed that the thermal decom- position of the nano-LDHs had four steps. Thereby the decomposition model of the nano-LDHs was supposed according to the analysis of their thermal decomposition. After PS, ABS, HDPE and PVC were filled with the nano-LDHs, their LOI values could be increased up to 28, 27, 26 and 33, respectively. When the fire-retardant coating contained 1.9% of the nano-LDHs that was 0.27 times the dosage of the conventional TiO2, its fire endurance time reached 32.75min that was 7.05 min longer than that of the best coating containing TiO2 according to the model big-panel combustion test method.

关键词： layered double hydroxides, nanocrystal, microwave synthesis, thermal decomposition, fire-retardant performance.

Orthogonal M-band compactly supported interpolating wavelet theory

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Science China(Technological Sciences) 1999年第6期42卷 567-583页

作者：张建康保铮 State Key laboratory for Radar Signal Processing Xidian University

Recently, 2-band interpolating wavelet transform has attracted much attention. It has the following several features: (i) The wavelet series transform coefficients of a signal in the multiresolution subspace are exactly consistent with its discrete wavelet transform coefficients; (ii) good approximation performance. (iii) efficiency in computation. However orthogonal 2-band compactly supported interpolating wavelet transform is only the first order. In order to overcome this shortcoming, the orthogonal M-band compactly supported interpolating wavelet basis is established. First, the unitary interpolating scaling filters of the lengthL =MK are characterized. Second, a scheme is given to design high-order unitary interpolating scaling filters. Third, a parameterization of the unitary interpolating scaling filters of the lengthL = 4M is made. Fourth, the orthogonal 2-order and 3-order three-band compactly supported interpolating scaling functions are constructed. Finally, the properties of the orthogonal M-band compactly supported interpolating wavelets and the approximation performance.of the Mallat projection are discussed. For the smooth signal inL 2(?), the asymptotic formula of the approximation enor of the Mallat projection is obtained, and for the band-limited signal, the quantitative estimate of its upper bounds is given. The results show that the Mallat projection has the same approximation order as the orthogonal projection, and particularly for the orthogonal even number-order M-band compactly supported interpolating scaling function, they have the same approximation performance. The quantitative result also shows that the selection of the initial scale depends on the distribution of the signal frequency and the regularity order of the scaling function. For the given scaling function and signal, using these results one can determine the initial scale and at the same time estimate the initial scaling coefficients without prefiltering according to the error re

关键词： orthogonal M-band compactly supported wavelets interpolating scaling filter and scaling function Mallat projection approximation performance.

A new environment-friendly refrigerant

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Science China(Technological Sciences) 1999年第2期42卷 183-189页

作者：赵晓宇史琳朱明善韩礼钟 Department of Thermal Engineering Tsinghua University

CFCs and HCFCs, widely used in refrigeration and air-conditioning equipment, have been or will be phased out according to the revisions of the Montreal Protocol because they deplete the ozone layer. Many substitutes have been proposed, but no one has perfectly replaced the CFC and HCFC refrigerants. New generation alternatives are being investigated worldwide. According to the industrial and environmental requirements, many factors should be considered in the screening and evaluation of refrigerant alternatives. A new method is proposed using the soft algebra method—fuzzy multiple evaluation. The weights for different factors are determined mathematically and criteria values for all the objects are made dimensionless to quantitatively compare the different alternatives. A new long-term drop-in mixture alternative THR02 is developed and evaluated in a series of theoretical and experimental evaluations. THR02 is proved to be an environment-friendly, nontoxic, inflammable, drop-in alternative to CFC-12 and HFC-134a. The thermal performance.of the compressors and refrigerators with THR02 as a drop-in is equal to or higher than with CFC-12 and HFC-134a. The compressor and refrigerator using THR02 perform reliably after long-period running.

关键词： alternatives fuzzy multiple evaluation method long-term drop-in thermal performance.

Atomic states and properties of Pt-electrocatalyst

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Science China(Technological Sciences) 2006年第3期49卷 291-296页

作者： PENG Hongjian XIE Youqing College of Chemistry and Chemical Engineering College of Materials Science and Engineering Central South University Changsha 410083 China College of Chemistry and Chemical Engineering College of Materials Science and Engineering Central South University Changsha 410083 China

Using the one-atom theory (OA), the atomic state of Pt-electrocatalyst with fcc structure was determined as follows: [Xe] (5dn)6.48 (5dc)2.02 (6sc)1.48(6sf)0.02. The atomic states of this metal with hcp and bcc structures of primary characteristic crystals and liquid state was also studied. According to its atomic states, the relationship between the atomic states and crystalline structure, catalytic performance.and conductivity was explained qualitatively. The potential curve, the temperature dependence of bulk modulus and linear thermal expansion coefficient of fcc-Pt were calculated quantitatively.

关键词： Pt-electrocatalyst, atomic states, crystalline structure, catalytic performance.

Dynamic performance.of On-off Operation for a Small Scale Direct Fired Absorption Chiller

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Journal of Donghua University(English Edition) 2001年第1期18卷 46-50页

作者： Wang Lei(王磊) Lu Zhen(陆震) Environment Science and Engineering College Dong Hua University Shanghai 200051 Energy and Power Institute Shanghai Jiaotong University Shanghai 200030

A part load operation by turning the burner on and off intermittently is effective for a small scale direct fired absorption chiller. The dynamic performance.of the system has been investigated. The relationship between pressure, temperature and concentration of the lithium bromide solution have been analyzed. The result obtained indicates that the pressure of the high pressure generator and the temperature of the exhausted smoke are the most sensitive parameters. It is also found that the transition time from a full load to a part load condition is quite long, and part load relative cooling capacity is almost near the intermittent running time ratio and oil consumption ratio.

关键词： direct fired, absorption chiller, part load, dynamic performance.

performance.Analysis of the Aeration Valves and Its Protections at the Generating Units in ITAIPU Hydroelectric Power Plant

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Journal of Mechanics Engineering and Automation 2014年第7期4卷 601-609页

作者： Joao Maria Marra Lucas Rafael Hara Motta Liliana Madalena Gramani Department of Maintenance Engineering Itaipu Binacional Foz do lguaqu 85856-970 Brazil Department of Mechanical Engineering Western Parana State University Foz do Igua~u 85857-900 Brazil Department of Mathematics Federal University of Parana Curitiba 80210-170 Brazil

With the growing energetic need present in the world, it is increasingly necessary for the researches and facilities to seek a better use of renewable natural resources. This paper is applied in the study of the performance.of the aeration system of the Francis turbines present in Itaipu Hydroelectric Power Plant. When a Francis turbine operates off its optimal conditions, a vortex is formed inside the draft tube that, besides produces cavitation and pressure fluctuations, can pulse at frequencies with risk of resonance with hydraulic system, producing efforts and vibrations that may cause structural failures in the turbines, generators and civil parts of the power house. These damaging effects can be reduced using atmospheric aeration of the turbines. Because of this, the availability and effectively of the aeration system is fundamental to smooth the behavior of the turbines, helping preserve the health of the power plant. An analysis of the performance.of the aeration system will be done using maintenance records and disturbances analysis reports （RAP）, allowing verification of the operating conditions of the turbine and fatality of water inlet in air pipes. Through the improvements detected, it is possible to reduce machine stoppages by tripping, thus increasing the availability of the turbines.

关键词： turbine aeration performance.

Adaptive Optimal Control of a Heavy Lathe Operation

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Journal of Mechanics Engineering and Automation 2014年第4期4卷 269-275页

作者： Viktor D. Kovalev Yana V. Vasilchenko Predrag Daasic Department of Machine Tools and Instruments Mechanical Engineering Faculty Donbass State Engineering Academy (DSEA)Kramatorsk 84300 Ukraine SaTCIP Publisher Ltd. Vrnjadka Banja 36210 Serbia

To create control laws of the cutting process on the heavy lathe, the temperature-force model of optimization of cutting conditions for turning was selected. The models to manage the process of cutting on heavy lathe in real time were created. It was found that the optimization of the cutting process must be carried out according to the criteria： productivity, cost and tool life. The hardware structure of the adaptive control system for heavy lathe was developed and its dynamic performance.was investigated. The system provides function of the cutting speed of adaptive control and the possibility of compensation of linear, nonlinear and temperature-related inaccuracies. Research results were implemented in the prototype of adaptive control system for heavy lathe and the integral complex of optimal control of an adaptive technological system.

关键词： Heavy machine tool cutting tools power cutting performance.

Assessment of Solar-Coal Hybrid Electricity Power Generating Systems

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Journal of Energy and Power Engineering 2012年第1期6卷 12-19页

作者： Moses Tunde Oladiran Cheddi Kiravu Ovid Augustus Plumb Faculty of Engineering and Technology University of Botswana Gaborone P/Bag 0061 Botswana Department of Mechanical Engineering University of Wyoming Laramie WY82071 USA

Botswana currently depends on electricity generated from coal-based power plant or electricity supplied from the border in South Africa. The country has good reserves of coal and the solar radiation is sufficiently high to make solar thermal attractive for generating electricity. The paper presents two conceptual coal-fired power station designs in which a solar sub-system augments heat to the feed heaters or to the boiler. The thermal and economic analyses showed enhanced system performance.which indicates that solar power could be embedded into existing fossil fuel plants or new power stations. Integrating solar energy with existing or new fossil fuel based power plants could reduce the cost of stand-alone solar thermal power stations, reduce CO2 emissions and produce experience necessary to operate a full scale solar thermal electricity generation facility.

关键词： Hybrid systems solar coal economics performance.