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731.
本文介绍了一种曲轴感应热处理的新工艺,该工艺不同于常规的工艺,曲轴不旋转.与传统的感应淬火设备的操作相比较,本文概述了该项新静态方法的技术优点,即节约成本和空间. 相似文献
732.
A discrete optimization approach for locating Automatic Vehicle Identification readers for the provision of roadway travel times 总被引:3,自引:0,他引:3
Hanif D. Sherali Jitamitra Desai Hesham Rakha 《Transportation Research Part B: Methodological》2006,40(10):857-871
This paper develops an algorithm for optimally locating Automatic Vehicle Identification tag readers by maximizing the benefit that would accrue from measuring travel times on a transportation network. The problem is formulated as a quadratic 0–1 optimization problem where the objective function parameters represent benefit factors that capture the relevance of measuring travel times as reflected by the demand and travel time variability along specified trips. An optimization approach based on the Reformulation–Linearization Technique coupled with semidefinite programming concepts is designed to solve the formulated reader location problem. To illustrate the proposed methodology, we consider a transportation network that is comprised of freeway segments that might include merge, diverge, weaving, and bottleneck sections. In order to derive benefit factors for the various origin–destination pairs on this network, we employ a simulation package (INTEGRATION) in combination with a composite function, which estimates the travel time variability along a trip that is comprised of links that include any of the four identified sections. The simulation results are actually recorded as generic look-up tables that can be used for any such section for the purpose of computing the associated benefit factor coefficients. Computational results are presented using data pertaining to a freeway section in San Antonio, Texas, as well as synthetic test cases, to demonstrate the effectiveness of the proposed approach, and to study the sensitivity of the quality of the solution to variations in the number of available readers. 相似文献
733.
ALSTOM公司推出了一种名为"e Transformer"的电子变压器,其重量轻、体积小,大大减少了钢材和铜材的使用量. 相似文献
734.
基于FPGA的MVB1类设备网卡的设计 总被引:12,自引:0,他引:12
考虑到MVB1类设备网卡支持简单的过程数据传送(功能代码为0~4)和设备状态响应(功能代码15),不支持消息数据、过程数据强制功能的情况,提出利用FPGA(现场可编程门阵列)开发MVB1类设备网卡。这样,在完成通信功能的同时,可以无需外加CPU即完成一些简单的IO、AD等功能,也可以设计出总线方式与CPU相连。实践证明MVB1类设备网卡采用PC104接口与宿主CPU连接,具有110个256位的过程数据通信能力;用FPGA开发MVB1类设备网卡比用MVBC芯片更具优势。 相似文献
735.
Richard P. Signell Sandro Carniel Luigi Cavaleri Jacopo Chiggiato James D. Doyle Julie Pullen Mauro Sclavo 《Journal of Marine Systems》2005,53(1-4):217-233
The quality of surface winds derived from four meteorological models is assessed in the semi-enclosed Adriatic Sea over a 2-month period: a global hydrostatic model ECMWF T511 (40 km resolution), a hydrostatic limited area model LAMBO (20 km), and two non-hydrostatic limited area models: LAMI (7 km) and COAMPS™ (4 km). These wind models are used to drive a 2 km resolution wave model (SWAN) of the Adriatic, and wind and wave results are compared with observations at the ISMAR oceanographic tower off Venice. Waves are also compared at buoy locations near Ancona and Ortona. Consistently with earlier studies, the ECMWF fields underestimate the wind magnitude and do not reproduce the known spatial structure of strong wind events. The results show that the higher-resolution, limited area models LAMI and COAMPS exhibit better amplitude response than the coarser ECMWF: there is a 3- to 4-fold reduction of the wind underestimation at the platform (from 36% to 8–11%). The wave response is also improved with LAMI and COAMPS: there is a 2-fold reduction in the underestimation of wave heights at the platform. These non-hydrostatic models also produce wind fields with more realistic small-scale, spatial structure during strong wind events. The temporal correlation between observed and modelled wind, however, is highest with the global ECMWF model due to the fact that large-scale features can be predicted deterministically, whereas small-scale features can only be predicted stochastically. Models with less small-scale structure have better correlation because they have less “noise.” This explanation is supported by increased correlation between modelled and observed waves, the waves representing a smoothing of the wind over fetch and duration. Although there is room for improvement, the high-resolution, non-hydrostatic models (LAMI and COAMPS) offer significant advantages for driving oceanographic simulations in semi-enclosed basins such as the Adriatic Sea. 相似文献
736.
Modeling emulsification after an oil spill in the sea 总被引:1,自引:0,他引:1
A conceptual model for simulating oil emulsification after a spill in the ocean is presented. This paper contains the complete model formulation and scenario simulations. The model formulation is based on the most up-to-date research information available in the literature. The model uses minimum turbulence energy as a criterion to determine whether emulsification occurs. Once the emulsification happens, the model simulates water uptake and viscosity changes during emulsification. The model classifies emulsion into three categories: stable, meso-stable, and unstable emulsions based on a concept “stability index”. The model estimates the stability of the emulsion and simulates the process of de-emulsification when the emulsion is meso-stable or unstable. The model also considers the effects of evaporation on the formation of emulsification. Scenario simulations show how different types of emulsions are formed under different conditions. They also show how the emulsion stability changes with oil weathering. 相似文献
737.
Variability of snow and ice thermal, physical and optical properties pertinent to sea ice algae biomass during spring 总被引:6,自引:2,他引:4
Changes in the thermal, physical and optical properties of the snow–sea ice system and feedbacks between various temporal and spatial scales affect accumulation of microalgae at the sea ice bottom and are the focus of this research. During the spring transition period, May 4 to June 9, 2002, we closely monitored atmospheric conditions and properties of the snow–sea ice system, including thermal, physical and optical properties of the snow cover (e.g., temperature, grain size, light attenuation), ice thickness and salinity, and biomass of bottom ice algae. Results show that snowdrift size averaged 31.2 by 10.6 m with a depth range of 2 to 45 cm. Snowpacks also varied in age, distinguished by coincident peaks of snow salinity and grain size and a lower PAR extinction coefficient. Spatial variability of the snowpack was superimposed by temporal variability associated with seasonal snow–ice melt and wind redistribution of snow. Maximum biomass of ice algae was observed under intermediate snow covers. Under thin snow covers, algae biomass declined steadily coincident with seasonal warming and desalination of the ice cover. Under thick snow covers, algae biomass was negatively correlated with snow depth. These results suggest that thin snow covers were associated with a thermal effect causing sloughing of algae, whereas under deep snow, algae were still light limited and thermally insulated from the warming atmosphere. Our results highlight the importance of snow cover history on the sea ice system operating below. Furthermore, in the context of current climate change scenarios, shifts in snow depth would result in decreases of ice algae biomass. 相似文献
738.
2008年9月11~12日,在卡鲁加定期举办了国际“运输基础装备和线路机械2008”展览会。在2008年的这个展览会上出现了新的情况,汇集了所有运输设施方向的专家(工务部门,电气化及供电部门,自动化及遥控部门的人员以及通信人员)参会,是本次展会的主要特点。超过130多家来自俄罗斯、独联体国家和西方国家的公司展出了自己的产品,其中包括现代化的铁道线路养护维修用的全套装备、自动机械和遥控机械装备、电气化装备等。 相似文献
739.
In the following paper, a numerical study of the atomization, vaporization and wall impingement processes of hollow-cone fuel
spray from high-pressure swirl injectors under various ambient temperature conditions was carried out. Also, the availability
of applied models and the effect of ambient temperature on spray characteristics is discussed. The Linearized Instability
Sheet Atomization (LISA) model combined with the Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model, the improved
Abramzon model and the Gosman model are used to calculate the atomization, vaporization and wall impingement processes of
hollow-cone fuel spray, respectively. Spray models are implemented with the modified KIVA code. The calculation results of
the spray characteristics under two ambient temperatures, including spray tip penetration, spray structure and radial distance
after spray-wall impingement are compared to the experimental results obtained by the Laser Induced Exciplex Fluorescence
(LIEF) technique. The droplet size distribution, ambient gas velocity field, vapor phase distribution and fuel film mass generated
by spray-wall impingement, measurements which are generally difficult to obtain by experimental methods, are also calculated
and discussed. Quantitative discussions on the effect of the ambient temperature on the spray development process are conducted.
It is shown that the applied models are applicable even in the high ambient temperature condition. 相似文献
740.
Development of fuel cell hybrid powertrain research platform based on dynamic testbed 总被引:1,自引:0,他引:1
An experimental research platform based on a dynamic testbed is developed and applied for fuel cell hybrid powertrain integration
and control. A driver brake model is added to the dynamic testbed to simulate the braking process of an electric vehicle.
Sub-systems of the fuel cell hybrid powertrain are tested, and characteristic parameters are obtained. A simulation platform
is constructed in LabVIEW environment, and its validity is verified by dynamic test results. A real time control system is
developed with an embedded PC for the function of rapid control prototyping. Using this platform, fuel cell battery hybrid
and fuel cell supercapacitor hybrid configurations are investigated. This platform provides a powerful tool for fuel cell
powertrain research and development. 相似文献