小型化准分子激光器气体性能的优化

对于新研制的准分子激光系统而言,激光气体的性能具有非常重要的作用,激光系统的混合气体配比与单脉冲能量、放电稳定性和寿命等性能参量有密切关系。为了获得最佳气体配比,在自行研制的小型化Xecl准分子激光器的基础上进行了激光气体性能优化实验,分析了Xe,HCl气体比例对激光性能的影响,通过理论分析和实验结果给出了Ne和He两种不同缓冲气体下的激光性能差异,并给出了该激光系统的优化气体成分和有效提高激光效率方法。实验结果为研制商业化小型准分子激光器件提供了支持和依据。

通过优化工作气体分压提高准分子激光器脉冲能量输出(英文)

分别研究了Ne、F_2和Kr对KrF准分子激光器脉冲能量输出的影响.理论分析了Ne作为缓冲气体在激光器放电过程中的碰撞过程,并对Ne与其他种类缓冲气体进行了对比分析.F_2分压对脉冲能量输出的影响非常明显。工作气体中Kr参与的三体碰撞过程占主导地位,激光脉冲能量输出与Kr分压呈二次函数关系。当充电电压为28.7 kV,在最优化工作气体分压(F_2:He:Kr:Ne=0.315:5.985:19.5:305 kpa)下获得的最大单脉冲输出能量为807 mJ,全电效率为1.64%.

基于亨利气体溶解度优化算法的电动汽车二阶段优化调度方法

针对如何有效管理电动汽车充电负荷,优化电动汽车充电调度以减少充电时间和能量消耗的问题,提出了一种基于亨利气体溶解度优化算法的电动汽车二阶段优化调度方法。第1阶段通过整数线性规划以各电动汽车能量消耗最少到达有充电空位的充电站为目标,将最适宜的充电站分配给电动汽车;第2阶段以充电站运营商日充电总费用最小为目标,考虑电动汽车充电率、能量需求和荷电状态等约束,基于亨利气体溶解度优化算法最大限度地降低充电站运营商的日充电总费用。最后,通过仿真实验将所提方法与粒子群优化算法、遗传算法等进行对比,仿真结果验证了所提方法的有效性。

基于多域特征优化的航空发动机传感器智能故障诊断

为解决对航空发动机传感器故障诊断时单域特征反映故障信息不全面问题,提出了一种基于优化的多域特征进行智能故障诊断的方法。该方法提取了传感器信号的时、频域特征和形态信息,共同组成多域特征,从多维度描述传感器的健康状况;并提出了一种新的元启发式算法—改进亨利气体溶解度优化算法(Boosted Henry gas solubility optimization,BHGSO)进行特征选择,尽量以最低维度但知识丰富的高品质信息来训练故障识别模型,以减轻计算负担,并提高诊断可靠性;最后将特征向量作为传感器的健康指标,基于深度置信网络(Deep belief network,DBN)实现智能故障诊断。仿真结果表明,该研究提出的方法能够对航空发动机传感器进行有效的故障诊断,且具有较高的准确度和较小的计算负担。

英台气田气体钻井技术研究

英台气田营城组储层具有可钻性差、常规钻井速度慢、敏感性强、易受工作液污染等特点,因此常规钻井方式难以准确评价自然产能,开发效益差。通过针对性的开展地质工程特征分析,并从地层三压力、井壁稳定性、地层流体情况等方面入手论证气体钻井可行性,然后从气体介质的选择、井身结构优化、注气量优选等方面开展气体钻井方案优化研究等工作,并成功在英深306-1井开展现场气体钻井。该研究在达到准确评价储层自然产能目标的同时,实现了提速、降本、增产。

基于FLUENT的燃烧轻气炮内置喷管增速效能研究

为研究燃烧轻气炮气室前端的内置喷管对弹丸速度和气体流动情况的影响,采用计算流体力学(CFD)方法,建立35mm汽油燃料轻气炮的流动基本控制方程和喷管流动一维数值模型,设弹重为20g、身管内壁面光滑且长度为1.5m,并在Fluent中编译UDF函数以计算弹丸运动参数,分析内置喷管对气流速度的影响以及弹丸运动速度的变化,以有无内置喷管为区别设置对照计算对比内置喷管的增速效能。结果表明:内置喷管构型利于提升弹后气流流速,减少气体回流,流速马赫数可提升至1.76,增幅约为9.3%;在燃烧温度、压力较高(>12MPa)时可大幅提升弹丸速度,最大速度约为670m/s,增幅约为6%~10%,反之则弹丸速度增效微弱(增幅2%~7%)。研究结果表明燃烧轻气炮配合内置喷管具有提升发射性能的效果,可为气体炮发射性能优化研究提供一定的理论参考。

A system for evaluation of ultrasound contrast agent's enhancement effect

A system for in vitro investigation of ultrasound contrast agent＇s enhancement effect is presented and evaluated. It includes the digital B-mode ultrasound scanner Belson3000A, the tissue-mimicking ultrasound phantoms and the software which is used for image quantitative analysis. The linear range, optimal settings and repeatability of the system are assessed and explored by scanning the ultrasound phantoms with different reflective intensities. The measurements are performed under an acoustic power from 4.8 to 12.3 mW, the scanner centre frequency is 3.5 MH and the gain setting is 50 dB. Both a self-made surfactant encapsulated microbubble and a commercial ultrasound contrast agent are scanned. The results show that the pixel intensity of ultrasonic images increases with the increase in the sound power, and for the stronger reflective phantoms of more particles, the increasing trend is much more evident. The system is optimal for evaluating the microbubble contrast agents＇ enhancement effects. It presents a simple, effective and real-time means for characterizing the enhancement ability of microbubbles.

Air interaction around outdoor air-cooled condensers

In order to increase cooling or heating efficiency,a porous computational fluid dynamics（CFD）model is employed to predict the thermo-fluid status and optimize the placement of outdoor units.A full scale model is established to validate the accuracy of CFD simulation in terms of velocity and temperature distributions.The comparison between the measurement and the simulation shows a good agreement.By evaluating the condensers＇ sucked air temperature with CFD for three units installed in a row,it is found that the minimum separation distance among neighboring units is 0.2 m;a vertical wall should be apart from the unit line by at least 0.8 m;and large different operating pressures among units do not impact the flow rate and the heat transfer of the other units meaningfully.

认知无线电网络的一种演化博弈频谱共享机制

为解决静态频谱分配策略导致资源浪费问题,采用认知无线电技术动态管理频谱,其中频谱共享是关键。为了使认知用户能够公平共享频谱,提出了一种认知无线电网络中的基于演化博弈的频谱共享机制。由于认知无线电网络具有动态、异构的特点,且无线信道不可靠、易受环境影响,因此采用模糊数学知识刻画与认知用户满意度相关的参数,利用气体布朗运动优化算法解决认知用户的频谱接入问题,利用演化博弈对认知用户之间的频谱共享建模。效用函数充分考虑频谱共享公平,按照模仿者动态模型求解动态均衡。仿真结果表明,该机制中认知用户能够获得更高效用。

Cavity noise sensitivity analysis of tire contour design factors and application of contour optimization methodology

Cavity resonance noise of passenger car tires is generated by interacting excitation between a tire structure and the fill gas (air), and generally lies in a frequency range of 200?250 Hz. As such, this noise is strongly perceived and may be a serious source of driver annoyance. Thus, many studies regarding the cavity noise mechanism and its reduction have already been conducted. In this work, a vibro-acoustic coupled analysis was conducted between a tire structure and air cavity. Using this analysis, we can more accurately simulate the tire noise performance in the region of the cavity resonance frequency. An analysis of the effects of variation of tire contour design factors was conducted, using design-of-experiments methods. Finally, a multi-objective optimization was performed using in-house codes to reduce the cavity noise level while minimizing the loss of other performances, such as diminished ride comfort and handling caused by the variations of contour. As a result of this optimization, an optimized contour shape was derived, which satisfied the multi-objective performances.

Gas drainage from different mine of drainage systems for deep coal areas： optimal placement seams with high gas emissions

The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applied successfully. However, as the mining depth increasing, parts of the gas drainage system are not suitable for mines with high gas emissions. Because larger mining depths cause higher ground stresses, it becomes extremely difficult to maintain long gob side roadways. The greater deformation suffered by the roadway is not favorable lor borehole drilling for continuous gas drainage. To solve these problems, Y-type ventilation and gas drainage systems installed from a roof roadway were designed for drainage optimization. This system was designed based on a gas-enrichment zone analysis developed from mining the 11-2 coal seam in the Zhuji Mine at Huainan, Anhui Province, China. The method of Y-type gas extraction from different mine areas was applied to the panel 1112（1） in the Zhuji Mine. The absolute gas emission rate was up to 116.3 m^3/min with an average flow of 69.1 m^3/min at an average drainage concentration of nearly 85 %. After the Y-type method was adopted, the concentration of gas in the return air was 0.15 %-0.64 %, averaging 0.39 % with a ventilation rate of 2100-2750 m^3/min. The gas management system proved to be efficient, and the effective gas control allowed safe production to continue .

The coalbed methane production potential method for optimization of wells location selection

A gas production potential method for optimization of gas wellsite locations selection is proposed in terms of the coalbed gas resources volume and the recoverability. The method uses the actual data about reservoirs in a coalbed gas field in central China to optimize wellsite locations in the studied area in combination with the dynamic data about actual production in the coalbed gas field, selects a favorable subarea for gas wells deployment. The method is established based on the basic properties of coal reservoirs, in combination with the coalbed thickness and the gas content to make an analysis of the gas storage potential of a coal reservoir, as well as resources volume and the permeability of a coal reservoir. This method can be popularized for optimization of wellsite locations in other methane gas development areas or blocks.

Optimization of pulsed current gas tungsten arc welding process parameters to attain maximum tensile strength in AZ31B magnesium alloy

An empirical relationship to predict tensile strength of pulsed current gas tungsten arc welded AZ31B magnesium alloy was developed. Incorporating process parameters such as peak current, base current, pulse frequency and pulse on time were studied. The experiments were conducted based on a four-factor, five-level, central composite design matrix. The developed empirical relationship can be effectively used to predict the tensile strength of pulsed current gas tungsten arc welded AZ31B magnesium alloy joints at 95% confidence level. The results indicate that pulse frequency has the greatest influence on tensile strength, followed by peak current, pulse on time and base current.

Actively Dealing with Climate Change and Striving to Strengthen the Capability of Sustainable Development

Either from the perspective of the finite supply capacity of global resources and energy,or from the perspective of global environment restrictive conditions,developing countries can not repeat the old development road of developed countries,either in view of the international pressure China is currently facing,or in view of China's own resources endowment and stages of development,we must actively face such a challenge of climate change.We must recognize that the issue of climate change may be a great restraint to the present and future eco-social development,and may also be an important driving force and new opportunity to push forward the transformation of development pattern,to take a new road of industrialization and to realize sustainable development.This demands us,on the one hand,to take the Scientific Outlook of Development as the guide to make efforts to control the emission of greenhouse gases and continuously increase the capability of adapting to climatic change,and set up the overall plan to respond to climate change of our country,and on the other hand,we should unswervingly take the road of sustainable development,save energy,optimize energy structure and strengthen biological protection in slowing and adapting to climate change.

Pneumatic resistance network analysis and dimension optimization of high pressure electronic pneumatic pressure reducing valve

The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.

Inertisation options for BG method and optimisation using CFD modelling

Spontaneous combustion(sponcom) is one of the issues of concern with the blasting gallery(BG) method of coal mining and has the potential to cause fires, and impact on production and safety, greenhouse gas(GHG) emissions and huge costs involved in controlling the aftermath situations. Some of the research attempts made to prevent and control coal mine fires and spontaneous combustion in thick seams worked with bord and pillar mining methods are presented in this paper. In the study, computational fluid dynamics(CFD) modelling techniques were used to simulate and assess the effects of various mining methods, layouts, designs, and different operational and ventilation parameters on the flow of goaf gases in BG panels. A wide range of parametric studies were conducted to develop proactive strategies to control and prevent ingress of oxygen into the goaf area preventing spontaneous combustion and mine fires.

New progress and future prospects of CBM exploration and development in China

Efforts to speed up China's coal bed methane (CBM) exploration developments related to production safety, optimization of energy structures, prevention of energy waste and reduction of greenhouse gas emissions are all of great significance. In order to strengthen CBM exploration and development in China and to encourage increased growth in the CBM industry, we firstly give a general overview of the recent technological innovations and other developments in CBM exploration in the U.S., Canada and other countries. Using this background information as the starting point, we further present observations and analyses of CBM exploration and development, preferential policies, technical support and implications of R&D for CBM development in China. The results show that the problems related to CBM exploration technology development and lack of a complete set of management policies are still the major issues slowing down the growth of domestic CBM industry. Development of resource exploration and technology, R&D and establishment of favorable government policy to support the industry and the creation of a relevant information platform, etc. are finally recommended.

Optimization Building Management

This paper demonstrates how achieving optimal integration between design and energy resources management can be particularly attractive in terms of energy consumption saving （cooling and heating） and lowering greenhouse gas emissions. The building automation system is based on innovative middleware framework which simplifies the modeling of a software for intelligent management of buildings and allows a multistandard and multiprotocol integration of sensors and actuators. The project has the target of underlining the economical opportunities and perspectives concerning the smart system adoption. Estimating the effects of home automation is essential to help its implementation, especially now that energy cost represents a consistent part of the house/building consumptions and will increase in the next few years. The results of the framework application in a residential building proves the validity of the proposed solution.

A comparative study of differential evolution and genetic algorithms for optimizing the design of water distribution systems

The differential evolution （DE） algorithm has been received increasing attention in terms of optimizing the design for the water distribution systems （WDSs）. This paper aims to carry out a comprehensive performarice comparison between the new emerged DE algorithm and the most popular algorithm-the genetic algorithm （GA）. A total of six benchmark WDS case studies were used with the number of decision variables ranging from 8 to 454. A preliminary sensitivity analysis was performed to select the most effective parameter values for both algorithms to enable the fair comparison. It is observed from the results that the DE algorithm consistently outperforms the GA in terms of both efficiency and the solution quality for each case study. Additionally, the DE algorithm was also compared with the previously published optimization algorithms based on the results for those six case studies, indicating that the DE exhibits comparable performance with other algorithms. It can be concluded that the DE is a newly promising optimization algorithm in the design of WDSs.

An Integrated Approach for Optimal Design of Micro Gas Turbine Combustors

The present work presents an approach for the optimized design of small gas turbine combustors, that integrates a0-D code, CFD analyses and an advanced game theory multi-objective optimization algorithm. The output of the0-D code is a baseline design of the combustor, given the required fuel characteristics, the basic geometry (tubularor annular) and the combustion concept (i.e. lean premixed primary zone or diffusive processes). For the optimizationof the baseline design a simplified parametric CAD/mesher model is then defined and submitted to a CFDcode. Free parameters of the optimization process are position and size of the liner hole arrays, their total area andthe shape of the exit duct, while different objectives are the minimization of NOx emissions, pressure losses andcombustor exit Pattern Factor. A 3D simulation of the optimized geometry completes the design procedure. As afirst demonstrative example, the integrated design process was applied to a tubular combustion chamber with alean premixed primary zone for a recuperative methane-fuelled small gas turbine of the 100 kW class.