Two new characteristic parameters for runoff computation

A method capable of estimating the hydrograph from a prescribed storm for a practical mild slope upstream catchment is proposed. This method makes use of two new characteristic parameters, andS, in conjunction with the kinematic wave equation to compute lateral inflows of the main stream of the catchment. The depth profile of overland flow at any instant within the catchment and hydrograph at any location can be easily found. Lag times for individual lateral inflows are then considered and are linearly combined to obtain the hydrograph at the outlet of the catchment or depth profile of the main stream at any instant. The validity of the excess rainfall-surface runoff linear relationship in this study has also been verified with Tatsunokuchiyama catchment, and it shows good results for this computed runoff.     

表面贴装过程仿真系统的研究与开发

文章从表面贴装技术(SMT)现状及特点开始,介绍多品种小批量电子产品中使用表面贴装技术存在的问题。针对这一情况对表面贴装过程仿真系统的需求进行了分析,并详细论述了仿真系统的文件预处理、仿真以及数据库维护三大主要模块设计,主要介绍采用OpenGL实现仿真模块的方法,同时展示仿真系统实现结果。最后总结了仿真系统的特点。     

Thermal accommodation coefficient of gases on controlled solid surfaces: Argon-tungsten system

The knowledge of the thermal accommodation coefficient for gases on well-controlled surfaces as a function of temperature is imperative to understanding the mechanism of interphase heat transfer on the microscopic level. With this goal in view, a heat transfer column instrument is designed, fabricated, assembled, and tested for the specific case a argon—tungsten system. With 99.9999%, pure argon, six sets of data are taken in the rarefied gas region in the maximum temperature range of 500–1500 K. Four sets of these measurements are in the temperature-jump region and are analyzed by the constant-power method to compute the thermal accommodation coefficient of argon on a controlled tungsten surface. The other two sets are taken under free-molecular flow conditions and are interpreted in accordance with the man-free-path kinetic theory for the low-pressure regime. These data are compared and discussed in the context of reported data in the literature and interpreted in the light of the surface condition and finish of the tungsten wire.Nomenclature A area of the solid surface - C _j constants in Eq. (3); j=0, 1, 2, 3, and 4 - E _i incident energy flux - E _r reflected energy flux - E _s reflected energy flux when the interaction between the gas and the solid atoms is complete - g temperature-jump distance - L half-length of the metal wire - M molecular weight of the gas - P gas pressure - Q _H total thermal energy conducted by the gas per unit time from the hot surface - Q_KT total thermal energy conducted by the gas per unit time if the striking gas molecules were to attain thermal equilibrium with the hot surface - R molar gas constant - r radial coordinate - r _f radius of the hot wire - S sticking coefficient - S_o initial sticking coefficient - T temperature - T _e linearly extrapolated gas temperature on the hot-wire surface - T _g temperature of the impinging gas molecules - T _H temperature of the hot surface - T _i temperature of the incident gas stream - T _r temperature of the gas molecules receding after collision with the solid surface - T _s temperature of the solid surface Greek Symbols thermal accommodation coefficient for the gas—solid surface - resistivity of the metal wire - gas coverage on the solid surface For an explanation of symbols, see Nomenclature.     

提高Cr12MoV钢冷作模具寿命的措施

从原材料改锻、预备热处理、淬火及回火、深冷处理、表面强化处理等方面分析介绍了提高Cr12MoV钢冷作模具寿命的一些方法和措施 ,并通过实例表明 ,采用这些方法和措施可较大幅度地提高模具寿命     

Ce对440C不锈轴承钢夹杂物演变的影响

为探究稀土Ce对440C不锈轴承钢中夹杂物的改性作用,利用实验室MoSi₂电阻炉对440C不锈轴承钢进行稀土Ce处理,采用OM、SEM等系统分析了Ce的添加对440C不锈轴承钢脱氧及夹杂物演变的影响。结果表明,随着Ce加入量的增加,其收得率逐渐升高。Ce的加入使钢中TO质量分数由0.002 5%降低至0.001 2%。未加入Ce的钢中夹杂物主要为Al₂O₃、MnS以及镁铝尖晶石;加入质量分数为0.011 5%的Ce后,夹杂物被改性为以Ce-Al-O为主的夹杂物;当Ce的添加量达到0.036 4%时,夹杂物被完全改性为Ce-O-S夹杂物。适量的Ce可以降低夹杂物尺寸及面积比例,但过量加入会使夹杂物尺寸变大。在本试验条件下,当Ce质量分数为0.011 5%时,钢中夹杂物细小弥散效果最明显。以上结论可为Ce在高碳铬不锈轴承钢中的应用提供参考。     

Characterization of blasted austenitic stainless steel and its corrosion resistance

It is known that the corrosion resistance of stainless steel is deteriorated by blasting, but the reason for this deterioration is not clear. A blasted austenitic stainless steel plate (JIS-SUS304) has been characterized with comparison to the scraped and non-blasted specimens. The surface roughness of the blasted specimen is larger than that of materials finished with #180 paper. A martensite phase is formed in the surface layer of both blasted and scraped specimens. Compressive residual stress is generated in the blasted specimen and the maximum residual stress is formed at 50–100 μm from the surface. The corrosion potentials of the blasted specimen and subsequently solution treated specimen are lower than that of the non-blasted specimen. The passivation current densities of the blasted specimens are higher those of the non-blasted specimen. The blasted specimen and the subsequently solution treated specimen exhibit rust in 5% sodium chloride (NaCl) solution, while the non-blasted specimen and ground specimen do not rust in the solution. It is concluded that the deterioration of corrosion resistance of austenitic stainless steel through blasting is caused by the roughed morphology of the surface.     

Multidisciplinary optimization of gas-quenching process

Distortion as a result of the quenching process is predominantly due to the thermal gradient and phase transformations within the component. Compared with traditional liquid quenching, the thermal boundary conditions during gas quenching are relatively simple to control. By adjusting the gas-quenching furnace pressure, the flow speed, or the spray nozzle configuration, the heat-transfer coefficients can be designed in terms of both the component geometry and the quenching time. The purpose of this research is to apply the optimization methodology to design the gas-quenching process. The design objective is to minimize the distortion caused by quenching. Constraints on the average surface hardness, and its distribution and residual stress are imposed. The heat-transfer coefficients are used as design variables. DEFORM-HT is used to predict material response during quenching. The response surface method is used to obtain the analytical models of the objective function and constraints in terms of the design variables. Once the response surfaces of the objective and constraints are obtained, they are used to search for the optimum heat-transfer coefficients. This process is then used instead of the finite-element analysis. A one-gear blank case study is used to demonstrate the optimization scheme.     

快干涂料铸渗法获得铸件表面复合层的研究

对快干涂料法铸渗工艺进行了研究。查明了影响铸件表面复合层质量的主要工艺因素,确定了最佳工艺参数,为生产实践提供了依据。     

不同活化剂对石油焦基活性炭孔结构的影响

以石油焦为原料 ,Na OH,KOH和 Na2 CO3 为活化剂制备活性炭 ,采用氮气吸附考察了不同活化剂对活性炭的比表面积、中孔和微孔孔径分布、孔容积及平均孔径等孔结构的影响 .结果表明 :KOH活化制备的活性炭包含 1 nm的微孔和 4nm的中孔 ,总孔容 0 .648cm3 /g,比表面积大 ;Na OH制备的活性炭以 1 nm的微孔为主 ,占总孔容 ( 0 .1 65 cm3 /g)的 98% ,平均孔径 1 .83nm;Na2 CO3 制备的活性炭以 4nm的中孔为主 ,占总孔容 ( 0 .1 43cm3 /g)的 68.5 % ,平均孔径 3.42 nm,比表面积小 .3种样品的孔径都呈现出多峰分布特征 .KOH和 Na2 CO3 活化制备的活性炭的 N2 吸附脱附曲线属于 型 ,Na OH活化制备的活性炭吸附脱附曲线属于 型 .     

The Structure of the Irreversibly Bound Adhesion Promoter-Substrate Interfacial Layer of γ-Aminopropylsilanetriol on Crystalline Si, as Measured by XPS and FTIR

The irreversibly bound interfacial layer deposited by the γ-aminopropysilanetriol adhesion promoter onto a crystalline silicon substrate, which remains even after profuse washing, was found by XPS to have resulted from the fragmentation and rearrangement of the original γ-aminopropylsilanetriol molecule. A mechanism is proposed, involving the homolytic scission of the terminal N-C bond. One of the subsequent reactions is believed to involve hydrogen loss by abstraction and the formation of a terminal vinyl group, which bonds to the substrate. Support for this mechanism is found in IR spectroscopy of this layer.