VELOCITY ANALYSIS OF A SPATIALM ECHANISM USING THE PRINCIPLEOF VIRTUAL FORCES

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区域热水采暖系统多目标稳态在线优化控制的动态仿真

提要通过创建直接连接区域热水采暖系统数学模型和多目标稳态在线优化模型,对此系统不同控制策略进行动态模拟。仿真结果显示单纯应用室外气候补偿控制不能获得预期的室温舒适性和节能效果,而采用基于多目标稳态在线优化控制策略不但能满足室温舒适性目标,且可获得近16%的节能效益。     

钻柱振动声波录井技术方法及应用实例

钻柱振动声波录井技术DVL（Drillstring Vibro-acoustic Logging）经过多年的室内研究和现场验证,已经取得了可喜成果,为了进一步完善其解释评价方法,该课题尚需要在现场试用中不断地深化应用研究,近期又一次开展了现场试验。简介了该技术的工作原理、配套硬件构成和无线数据传输系统的特点。结合现场应用实例．阐述了DVL技术发展最新的理论分析方法和研究成果;给出了DVL技术分析中的相关分析法和信号能量计算法;列举了频聚法、能聚法和归一化数据处理方法的理论公式和其应用方法。通过应用实例证实,依据DVL频谱图、频聚和能聚曲线、能量和相位差曲线,能有效地识别地层岩性,划分地层和油藏。同时在钻具工况的分析、辅助识别上能起到了一定的作用,为DVL技术的发展奠定了理论基础。     

Aerosol optical characteristics from a summer campaign in an urbancoastal Mediterranean area

The authors present a preliminary study of some optical properties of atmospheric aerosols over the area of Valencia, Spain, a coastal Mediterranean city. Measurements of spectral direct irradiance in the 300-1100 nm range were taken simultaneously at three sites: rural-continental, rural-coastal, and urban-coastal, all located within a 50 km radius of the city of Valencia. The irradiance measurements were obtained using three Li-cor 1800 spectroradiometers provided with radiance limiting tubes with field of views (FOVs) of 4.7°. The measurements were made under clear sky conditions during a field campaign carried out in the summer of 1998. In order to avoid the uncertainties associated with the determination of the water vapor content and the other atmospheric constituents, the analysis of the spectral aerosol optical thickness (AOT) values was limited to the 400-670 mm spectral band. From the values of the spectral AOT, both the Angstrom coefficients and the aerosol size distributions were obtained. The results show the great dependence of the optical aerosol characteristic on the direction of the prevailing winds (maritime or continental) in this area     

MODELLING OF MICROSTRUCTURE EVOLUTION AND PROPERTIES OF LOW-CARBON STEELS

1.IntroductionMicrostructureprocessmodelsareincreasinglyonhotstriprollingofste.l[1--7].Thesemodelsfrequentlyincorporateagreatdealofempiricismwithcomparativelytightprocessrangesofapplicability.Morefundamentallybasedprocessmodelsarerequiredtodeveloppredictivetoolstooptimizetheproductionforawiderangeofmilldesignsandprocessingconditions.Theprocessofhotstriprollingoflow--carbonsteelscanbesubdividedintothreeprin-cipalstages:(i)reheating,(n)rollingand(iii)cooling(watercoolingontherun--outtableandsubs…     

ELIMIMATION OF RANDOM DEFACTS IN AEROSPACE MATERIALS

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EFFECT OF RARE EARTH ADDITIONS ON FRACTURE PROPERTIES OF 2.25Cr-1Mo STEELS

The inclusion parameters,fracture surface morphology and void growth characteristics of ten-sile and fracture toughness specimens of 2.25Cr-1Mo steels with and without rare-earth(RE)additions have been investigated by quantitative metaltography(QTM),scanning elec-tron microscopy(SEM)and energy dispersive spectroscopy(EDS).There is a substantiallyhigher density of inclusions in the RE-treated steel,which has lower values of fracture proper-ties including critical values of COD and J integral(δ_c and J_(IC)),fracture strain(ε_f)and Charpy V-notch energy(CVN).The fracture surface of the RE-treated steel comprisesequiaxed dimples of diameters comparable with its inclusion spacing,whereas for thenon-RE-treated steels,a wide range of dimple sizes is found with average diameter muchsmaller than the corresponding inclusion spacing.The investigation indicates that the lowervalues of fracture properties for the steel with RE at room temperature may be ascribed to itslarge content of RE-containing inclusions.     

Enthalpy Probe Technique for Thermal Plasma Diagnostics

The measuring principle and experimental results of the enthalpy probe technique for thermal plasma diagnostics are presented. Its calibration and errors are discussed. Typical results are presented for the system operation in an Ar/H2(5 % H2) plasma arc jet under a reactor chamber pressure of 101.3 kPa. The plasma temperature and velocity profiles are measured. The center temperature and velocity are 6600 K and 850 m/s for plasma power 9 kW at axial locationof 17 mm.     

A 64-bit microprocessor in 130-nm and 90-nm technologies with power management features

The first two members in a family of 64-bit superscalar microprocessors are presented. The 130-nm processor, which was introduced first, offers 5-way instruction dispatch, support for 4-way integer and floating-point single-instruction multiple-data (SIMD) operations, a 512-kB second level (L2) cache, and a high-speed external bus. The 90-nm processor is a technology remap of the 130-nm design. It retains the features of the 130-nm processor and adds others, including a new power management facility. The architecture, device characteristics, power management, and thermal details of these two processors are described. In addition, the dataflow layout, aspects of the circuit design, clocking, and timing are discussed.     

A method for the incorporation of parametric uncertainty in the weighted evaluation multi-attribute decision analysis model

We develop an extension of the classic Weighted Evaluation (WE) Multi-Attribute Decision Analysis (MADA) model that allows for uncertainty in the parameters of the model. Uncertainties in attribute importance weights and alternative evaluation ratings are represented by independent uniform, triangular or beta random variables; and an iterative multi-variate integration scheme is used to evaluate the mean, variance and skewness of the resulting Probabilistic Weighted Evaluation (PWE). These moments are used to compute two-term Edgeworth and normal approximations to the distribution of: (a) the PWE for each of several alternatives that are to be analysed separately; or (b) the difference between PWEs for selected alternatives that are to be analysed on a pairwise basis. The proposed methodology is used to compare probabilistically three alternative solutions to the Mexico City Airport Siting Problem of Keeney and Raiffa (Keeney, R. L. and Raiffa, H., Decisions with Multiple Objectives. Wiley, New York, 1976).