美海军舰艇编队协同作战能力CEC系统研究综述

协同作战能力 CEC 大大提高了美军的防空反导能力,本文对美海军舰艇编队协同作战能力 CEC 系统进行了综述：(1)描述了 CEC 系统的构成,阐述了 CEC 系统的工作原理和工作流程,给出了 CEC 条件下的舰艇编队协同作战的指挥控制网;(2)分析了 CEC 与 Link16/11、 GCCS 等数据链的关系,对比了三者之间的差异;(3)分析了 CEC 系统与“宙斯盾”作战系统的关系,对比了两者之间的差异。     

An experimental study on the spray characteristics of a dual-orifice type swirl injector at low fuel temperatures

The objective of this study is to investigate the effects of fuel temperature on the spray characteristics of a dual-orifice type swirl injector used in a gas turbine. The major parameters affecting spray characteristics are fuel temperature and injection pressure entering into the injector. In this study, the spray characteristics of a dual-orifice type swirl injector are investigated by varying fuel temperature from — 30°C to 120°C and injection pressure from 0.29 to 0.69 MPa. Two kinds of fuel having different surface tension and viscosity are chosen as atomizing fluids. As a result, injection instability occurs in the low fuel temperature range due to icing phenomenon and fuel property change with a decrease of fuel temperature. As the injection pressure increases, the range of kinematic viscosity for stable atomization becomes wider. The properties controlling the SMD of spray is substantially different according to the fuel temperature range.     

Minimization of hot spot in a microchannel reactor for steam reforming of methane with the stripe combustion catalyst layer

Hot spot formation is inevitable in a heat exchanger microchannel reactor used for steam reforming of methane because of the local imbalance between the generated and absorbed heat. A stripe configuration of the combustion catalyst layer was suggested to make the catalytic combustion rate uniform in order to minimize the hot spot near the inlet. The stripe configuration was optimized by response surface methodology with computational fluid dynamics. With the optimal catalyst layer, the hot spot was not observed near the inlet and the maximum temperature decreased by 130 K from that of the uniform catalyst layer without any conversion loss. The maximum relative particle diameters of the uniform and the optimal stripe catalyst layer were about 3.68 and 2.51, respectively, and the surface-averaged particle diameter of the optimal stripe catalyst layer was 7.64% less than that of the uniform stripe catalyst layer.     

Numerical evaluation on the performance of advanced CO2 cycles in the cooling mode operation

A cycle simulation model was developed to predict the performances of the basic and advanced CO₂ cycles. The simulation model for the basic CO₂ cycle was validated by comparing the predicted data with the experimental data at the standard cooling condition. Cycle simulations of the advanced CO₂ cycles were carried out by varying the design parameters and operating conditions. The advanced CO₂ cycles considered in this study are as follows: a single-stage CO₂ cycle with an expander, a two-stage CO₂ cycle with an intercooler, and a two-stage CO₂ cycle with a vapor injection. The expander CO₂ cycle yielded a 28.3% improvement of the cooling COP over that of the basic CO₂ cycle at the expander efficiency of 30%. The two-stage CO₂ cycle with the intercooler yielded a 13.1% improvement of the cooling COP at the intercooling pressure of 6 MPa. The two-stage CO₂ cycle with vapor injection yielded an 18.3% improvement of the cooling COP at the low pressure side mass fraction of 70%.     

Performance optimization of a Lorenz-Meutzner cycle charged with hydrocarbon mixtures for a domestic refrigerator-freezer

A Lorenz-Meutzner cycle (called the “LM cycle”) for a domestic refrigerator-freezer (RF) has energy saving potential because of lower entropy generation in the fresh food compartment (R)-evaporator and lower compression ratio due to higher mean evaporating temperature, compared to a conventional cycle using pure refrigerant. In this study, a thermodynamic analysis for the optimum compositions of hydrocarbon (HC) mixtures and cycle specifications was performed. In addition, the effects of the refrigerant charge, capillary tube, compressor capacity, and mixture composition on the performance of the LM cycle using R-290/R-600 were investigated experimentally. Based on the experimental data, the energy consumption of the optimized LM cycle using R-290/R-600 (40:60%) was 11.2% lower than that of a bypass two-circuit cycle using R-600a in the same RF platform.     

版图设计导致薄膜电阻率不均匀性的研究

在薄膜混合集成电路的制作过程中,由于基片布线版图设计的电阻面积与导线面积的比例失调,薄膜电阻因受工艺加工过程中发烟硝酸去胶和热处理的影响而出现严重的电阻值不成比例偏离效应。这主要体现在R_□值随该电阻所连金属面积与该电阻面积比例的增大而增大。     

Modeling of frost growth and frost properties with airflow over a flat plate

A physical model of frost layer growth and frost properties with airflow over a flat plate at subfreezing temperature was developed. Frost roughness was measured, and an empirical correlation for the average frost roughness was suggested. Heat and mass transfer coefficients were calculated using the modified Prandtl mixing-length scheme containing the effects of both frost roughness and turbulent boundary layer thickness. Frost thermal conductivity was theoretically analyzed by solving the combined equations of air equivalent conductivity and thermal conductivity of the frost inner layer. Based on the present model, heat and mass transfer coefficient, frost thermal conductivity, frost thickness, frost mass concentration and frost density with time and space were estimated. The model showed good agreement with the basic trends of the test data taken from other literature. Spatial and temporal changes of heat flux and frost surface temperature were also investigated.     

Performance characteristics of a simultaneous cooling and heating multi-heat pump at partial load conditions

A simultaneous cooling and heating multi-heat pump can improve thermal comfort and energy efficiency through heat recovery at partial load conditions. The performance of a simultaneous heating and cooling multi-heat pump with four indoor units was measured by varying the compressor speed, EEV opening, and fan speed at full and partial load conditions in five operating modes. In the cooling-only and heating-only modes, the heating and cooling capacities were properly controlled by varying the compressor speed. However, in the cooling-main and heating-main modes under partial load conditions, a large imbalance between the cooling and heating capacities was observed even though the compressor speed was optimized. This capacity imbalance under partial load conditions was optimized by adjusting the EEV openings in the mode change unit and the outdoor unit. In addition, in the entire-heat recovery mode, rating compressor speed ratios were proposed under the full and partial load conditions.     

放电气体对ECR-PECVD法制备微晶硅薄膜的影响

用电子回旋共振等离子体增强化学气相沉积(ECR-PECVD)法制备微晶硅薄膜,研究了放电气体对薄膜沉积速率、薄膜中H含量、择优取向和结晶度的影响。结果表明,以Ar作为放电气体时薄膜沉积速率比以H2作为放电气体时高1.5—2倍,但是薄膜的结晶度较低;以Ar作为放电气体时薄膜的H含量比以H2作为放电气体时的薄膜低;放电气体对薄膜的择优取向和晶粒度没有显著的影响。