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881.
对新研制的两种电解防污开关恒流源所采用的不同逆变器、开关功率管、直流工作电源及取样方式的工作状态、工作特性进行了分析比较。在研制过程中,重点解决了恒流电源工作的安全可靠性、稳定性、抗干扰能力及输出范围宽等问题。 相似文献
882.
本文研究了用金属有机物热发解法制备PLT8薄膜的工艺过程和基片对薄膜结构的影响,并且给出了铁电性能的测量结果。 相似文献
883.
采用自行研制的LB自动提膜装置,制备出大面积(10×8cm2)、高质量的PMMA超薄抗蚀剂膜,并将其用于高分辨率铬掩模版的研制。通过电子束曝光,湿法蚀刻,制作了分辨率优于0.5μm,特征线宽0.38μm的4(100mm)铬掩模版。 相似文献
884.
We describe the design and operation of a new high-pressure metal ebulliometer which can operate at pressures to at least 3 MPa in the range 220–400 K. Infinite-dilution activity coefficients are presented for the system CHF2Cl + CF3-CH, at 275 K and for the system CF3-CH2F + CH2F2, at 260, 230, and 300 K. The Wilson activity coellicient model and a virial coefficient model are applied to these systems, and the phase equilibrium conditions are calculated. The results are shown to agree well with predicted and with published measured values. The excess enthalpy is calculated and compared with results from a Peng Robinson equation of state. Vapor densities on the dew curves are given. 相似文献
885.
汤炳谦 《固体电子学研究与进展》1996,16(1):48-55
叙述了Ba(Zn1/3Ta2/3)O3介质谐振器材料的制备、结构、微波性能及典型应用。Ba(Zn1/3Ta2/3)O3介质材料介电常数εr为29.5,频率温度系数τ≈0(-55~+85℃),10GHz下最大无载Q值14700,在28GHz测得Q值约为4800。这种材料具有高Q值,特别适用于X以上波段作为振荡器电路中频率稳定元件。用这种介质谐振器已研制出8mm介质稳频微带耿氏振荡器,频率稳定度小于10×10-6/℃,最大输出功率达180mW。 相似文献
886.
Y. Murat Elin Mehmet Saak 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(2):174-180
This paper presents the results of urease immobilization onto methacrylic acid–acrylamide grafted poly(ethyleneterephthalate) fibres. The graft yield strongly affected the maximum activity of the immobilized enzyme up to a value of 70·2%. Higher grafting caused a decline in urease activity and led to the degradation of the fibres. The minor changes observed in Km and Vmax demonstrated that the conformational changes existed during immobilization were not extensive. However, 70·2% methacrylic acid–acrylamide-g-fibres containing urease were more stable towards acidic and alkaline pH, high temperature and storage conditions compared with free enzyme. Apart from the increase in stability to heat inactivation, the initial enzymatic activity of the urease–fibre system remained almost unchanged even after 40 repeated assays corresponding to 10 h of operation in 4 months, indicating the excellent durability of the system. 相似文献
887.
M.F. Pinnell 《Composites Science and Technology》1996,56(12):1405-1413
The effect of matrix and fiber properties on the strengths and failure processes of notched, continuous-fiber composite specimens has been investigated. Bearing, open and filled hole tension and compression tests were conducted on AS-4/3501-6, IM-8/3501-6, AS-4/APC-2 and IM-8/APC-2 specimens. Failure characteristics of tested specimens were studied by fractographic techniques. Failure progression was tracked by means of incremental loading, radiography and fractographic inspection. 相似文献
888.
材料合成新技术──自蔓延高温合成 总被引:3,自引:0,他引:3
自蔓延高温合成(SHS)是目前被广泛开发用于工业陶瓷和其它先进材料制备的一种独特的先进工艺技术。本文对生产高科技材料的自蔓延高温合成技术方法进行了介绍,并分析了该工艺的特点及其理论基础,同时还讨论了影响材料合成的因素。 相似文献
889.
A numerical study of the transport phenomena arising in a single-screw extruder channel is carried out. A non-Newtonian fluid
is considered, using a power law model for the variable viscosity. Chemical reaction kinetics are also included. Finite difference
computations are carried out to solve the governing set of partial differential equations for the velocity, temperature and
species concentration fields, over a wide range of governing parameters for the case of a tapered screw channel.
The numerical treatment for this combined heat and mass transfer problem is outlined. A marching procedure in the down-channel
direction is adopted and the validity of the scheme for practical problems discussed. For large viscous dissipation, the material
heats up considerably due to the prevailing shear field, affecting the viscosity significantly, and results in large changes
in the pressure development at the end of the channel. The rate of reaction controls the mass diffusion rate which in turn
affects viscosity and the flow significantly. The dimensionless throughput,q
v
, is one of the most important parameters in the numerical solution. The dimensionless pressure variation is very sensitive
toq
v
, and orders of magnitude changes are possible for small variations inq
v
. Schemes for dealing with other important effects such as back flow, heat transfer by conduction in the barrel, and the effect
of the die are also outlined.
A list of symbols is given at the end of the paper
This is publication No. F-10544-4-91 of the New Jersey Agricultural Experiment Station supported by State Funds and the Center
for Advanced Food Technology (CAFT). The Center for Advanced Food Technology is a New Jersey Commission on Science and Technology Center. This work was also
supported in part by the US Army Research Office. 相似文献
890.