327 research outputs found

    Study on Optimization of Hydrogen Production Conditions and Immobilization

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    当今社会能源危机和环境污染问题受到越来越多的关注,开发新的能源体系已成为世界各国的共识。氢气由于其本身无色、无嗅、无毒且燃烧后仅生成水而被认为是理想的清洁能源。另外,氢气的能量密度高,每千克氢气的热值为143MJ,约为石油热值的3倍;它可以气态、液态或固态金属氢化物的形式储存,能适应各种应用环境下的不同要求,因而“氢经济”成为各国经济发展规划的重要组成部分。 本研究探讨了氮源、碳源、葡萄糖浓度、温度、以及初始pH值对产酸克雷伯氏菌HP1产氢的影响。单因子实验结果表明:碳源对产氢量的影响远远大于氮源,;综合考虑确定以硫酸铵(2g/L)和蛋白胨(1g/L)为氮源,;葡萄糖为最适碳源;培养转速选择...With the development of economy, people in the whole world pay more and more attention to energy scarcity and environmental pollution. Developing new energy system is being arranged by most of main countries. Hydrogen has been considered as one of the most ideal future energy, because it is clean, pollution-free, high heat value and can be stored and transported very easily. “Hydrogen economy” is ...学位:工学硕士院系专业:化学化工学院化学工程与生物工程系_生物化工学号:20043300

    Game Analysis on the Regulatory Reform of Chinese Telecommunications Industry Based on the Perspective of Interest Groups

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    由于自然垄断行业本身所具有的经济、技术等特征以及长期以来垄断的市场格局使得自然垄断行业的改革步履维艰。而电信行业本身所具有的网络经济、规模经济以及范围经济的特征决定了电信行业的天然垄断性,打破垄断、引入竞争成为电信行业规制改革的一个重要目标。改革开放以来,随着社会的发展以及技术的进步,我国对电信行业也进行了一系列的改革,电信市场从最初的政企合一、行政垄断逐步转变成为垄断竞争的市场结构,在很大程度上促进了我国电信业的繁荣发展,但是始终没有改变电信行业寡头垄断的市场格局,公平与效率始终是规制改革的一个难题。 目前,电信行业新一轮的重组改革已落下帷幕,全业务运营、3G时代的到来揭开了中国电信行业的...It is difficult to reform Chinese natural monopoly industries due to the economic and technological characteristics of natural monopoly industries and the traditional monopoly pattern formed in a long period. The telecommunications industry characteristics of network economy, scale economy and scope economy have led to natural monopoly of the telecommunications industry. To break the monopoly and ...学位:经济学硕士院系专业:经济学院经济系_政治经济学学号:1532007115152

    Research on the Clinical Pathway PDCA Continuous Improvement System Based on the Theory of Feedback Closed-loop Control System

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    运用控制论方法,将控制理论领域反馈的闭环控制法、管理学的PDCA循环等方法运用于信息系统的整合建设,建立电子病历一电子医嘱一临床路径一医院管理信息系统的“全闭环”临床路径执行和反馈体系,建立了疾病诊疗规范制定、临床操作服务、过程质量监管三位一体的医疗服务安全质量监测与持续改进闭环体系,临床路径信息管理平台对加强医疗服务安全动态监管,促进科学化、精细化、专业化管理,改善服务水平,提高效率具有不可或缺的重要作用。With the method of control theory, the feedback closed loop control method in the field of control theory, PDCA circulation of management and other methods are applied to the integrative construction of information system. The "closed loop" clinical pathway implementation and feedback system of electronic medical records-electronic medical advice-clinical pathway- hospital management information system is established. The medical service safety quality monitoring and continuous improvement closed-loop system integrating disease diagnosis and treatment specification formulation, clinical operation service and process quality supervision is set up. The clinical path information management platform has an indispensable important role on strengthening the dynamic supervision of medical service security, promoting scientific, refined and professional management, and improving the service level and eficiency.国家自然科学基金面上项目一大数据驱动的抗菌药物使用与管理决策优化研究(编号:71672160

    Influence of Particle Damper Configurations on the Dynamic Characteristic for Gear Transmission System

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    齿轮传动正朝着高速、重载和高精度方向发展,对其动态性能要求越来越高。颗粒阻尼通过颗粒间、颗粒与阻尼器壁间的非弹性碰撞和摩擦作用耗能,具有减振效果; 显著、耐高温、各向同性、对原结构改动小等优点。利用有限元法对齿轮进行了有预应力的模态分析,通过齿轮系统动力学分析,研究单双齿啮合激励对齿轮传动的; 影响;同时建立齿轮传动离心场中颗粒系统耗能模型,将离散元法计算颗粒系统耗能和试验测试对比,分析阻尼器配置对齿轮传动系统动特性的影响。结果显示,阻; 尼器配置方案是影响齿轮传动系统动特性的一个重要因素,在阻尼孔中填充一定数量的颗粒,当阻尼器总体积相同且齿轮结构静刚度相差不大时,阻尼器个数越多颗; 粒系统能耗越大;当阻尼孔直径相同时,阻尼孔个数越多颗粒系统总能耗越小;当阻尼孔个数相同时,阻尼孔直径越大颗粒系统能耗越小。通过试验和仿真对比验证; 了模型的正确性,为颗粒阻尼在离心场中的应用提供重要的理论依据。The gear transmission is advancing towards high speed, heavy load and; high precision. The requirements for the dynamic performance of gear; system are urgently proposed. The particle damping dissipates mechanical; system energy through inelastic collisions and friction between; particles. It is an effective and simple measure for vibration; reduction. It has many advantages, such as isotropy, high temperature; resistance and less modification to the original structure. This paper; has conducted the prestressed modal analysis of gear system by the; finite element method. Based on the dynamics analysis of gear system,; the effect of single tooth and double teeth meshing incentive on gear; transmission has been analyzed. The energy dissipation model of particle; damping for gear transmission in centrifugal field has been established.; By contrasting theoretical analysis and the test, the effect of damper; configuration on dynamic characteristic of gear transmission system is; analyzed. The results show that damper configuration is an important; factor of the dynamic characteristic for gear transmission system.; Filling a certain number of particles, when the gears static stiffness; are similar and the total dampers volume are equal, the more damping; hole, the greater the total energy loss. When the damping holes diameter; are the same, the more number of damping hole, the smaller the total; energy loss. When the damping hole number is the same, the bigger the; diameter, the less the total energy loss. Experimental results are; consistency with the theoretical analysis. These results can provide; guidelines for the application of particle damping in centrifugal field.国家自然科学基金; 福建省重点科技专项; 中央高校基本科研业务费专项资金; 福建省高端装备制造协同创新中心资助项

    Intensity Distribution Design for Laser-Induced Thermal Loading Based on Numerical Simulation

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    To accomplish laser-induced thermal loading simulation tests for pistons,the Gaussian beam was modulated into multi-circular beam with specific intensity distribution.A reverse method was proposed to design the intensity distribution for the laser-induced thermal loading based on finite element(FE) analysis.Firstly,the FE model is improved by alternating parameters of boundary conditions and thermal-physical properties of piston material in a reasonable range,therefore it can simulate the experimental resul..

    口腔扁平苔藓病的相关因素研究

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    本文观察了54例单纯口腔扁平苔藓(OLP)男女患者,发现患者组在负性生活事件分、总生活事件分、SAS和SDS积分上显著高于健康人对照组,同时患者组还存在T细胞亚群平衡紊乱、口腔粘膜微循环(OMC)障碍。糜烂型病根较重OLP患者组在焦虑程度、CD+8细胞数百分率和OMC综合积分等项目上显著高于非糜烂型病根较轻OLP患者组。提示心理应激与OLP疾病密切相关,T细胞亚群功能和OMC障碍程度与OLP病损相关。</p

    Effect of the Construction of Green Belts on the Attenuation of Traffic Noise along the Urban Trunk Roads in Xiamen City

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    通过对厦门市主干道绿化带种类结构调查以及噪声测定等,分析了厦门市主干道绿化带结构及其减噪效果。结果表明,厦门市主干道绿化带可分为4种结构:单一乔木型、乔木+疏灌木/绿篱型、乔木+密灌木型以及乔木+小乔木+灌木/绿篱型,带宽多在4~10M。厦门市主干道绿化带总体减噪能力为0.93~12.96db,绿化带对交通噪声超标治理率达70%。绿化带减噪能力y(db)与带宽X(M)呈显著的线性关系:y=1.2251X+0.2416(r2=0.8603);绿化带的附加衰减与总衰减亦呈显著正相关:y=0.4535X+0.2698(r2=0.9242),噪声的附加衰减主要受绿化带结构的影响,上述四种结构对噪声附加衰减平均值分别达0.93、2.25、4.43和6.72db。绿化带的宽度和结构均是影响其减噪效果的关键因素。Through site investigation and noise monitoring, the effects of the construction of green belts along the urban trunk roads in Xiamen Island on the attenuation of noise has been studied.The results show that the construction of green belts along the trunk road can be divided into four kinds of types as bellows: type I, single arbor; type II, arbor + shrub; type III, arbor + sub-arbor and type Ⅳ, arbor + sub-arbor + shrub.Their width varied among 4--10 m.The noise-reducing ability (y, dB) of the green belts varied from 0.93 to 12.96 dB with various belt widths (x, m), and can be expressed as following: y=1.2251x+0.2416.Meanwhile the additive attenuation of traffic noise (y, dB) presents a closely linear relationship with the total noise-reducing ability (x, dB) as following: y=0.4535x+0.2698 (R2=0.9242).Meanwhile, the additive attenuation of traffic noise is main affected by the constructions of green belts, which reached 0.93, 2.25, 4.43 and 6.72 dB, respectively for the above four kinds of construction types.It shows that the width and construction of green belts play the same important role to reduce the traffic noise

    塔里木沙漠公路防护林土壤微生物生物量与土壤环境因子的关系

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    为探讨极端干旱区风沙土土壤微生物与土壤环境因子的作用规律,采用相关分析法研究了塔里木沙漠公路防护林地土壤微生物生物量与理化因子和酶活性的关系.结果表明:土壤容重和粒径减小(R0.85)时,防护林地中土壤微生物数量和生物量有增大趋势,由容重与微生物量的相关性主导;土壤养分含量与土壤微生物数量和生物量呈正相关,主要由速效养分和放线菌、微生物生物量C、P的相关性所致;土壤酶活性与土壤微生物数量和生物量的相关性差异较大,R在0.51~0.91,主要取决于蔗糖酶、磷酸酶与放线菌、微生物量C的相关;土壤盐分增加不利于土壤微生物生物量的积累(R0.63).实践中应为干旱区林地土壤微生物营造良好的土体,促进土壤物质循环

    塔里木沙漠公路防护林生态工程的综合生态环境效应

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    为了探讨重大工程的生态环境效应,从风沙环境、土壤环境、小气候、生物多样性和地下水环境5个方面对塔里木沙漠公路防护林工程的综合生态环境效应进行了研究.结果表明:(1)防护林改变了近地表风沙运动过程,防沙体系内风速、输沙率降低幅度分别达64%~80%和87.45%~99.02%,风沙流结构、沙物质粒度、地表蚀积状况也发生了明显变化;(2)与自然流沙地相比,防护林土壤容重减小,全盐含量、总孔隙度和含水量增大,土壤肥力质量明显提高,其变化基本呈现"先快后慢"的规律;(3)防护林对于小环境改善作用明显,距地面6m范围内,林地不同高度的空气温度普遍低于自然流沙地,而空气湿度则高于自然流沙地,林地土壤温度也低于自然流沙地;(4)随着防护林内生境的变化,土壤微生物种类显著增加,但不同种类微生物的种群分布并不均匀;(5)目前防护林灌溉抽水对地下水位、地下水矿化度的影响不大,水位在厘米级范围波动,矿化度的变化幅度在±1g·L-1左右,且没有明显的变化趋势

    三维CT影像资料测量国人心尖区心肌变薄的解剖学验证

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    背景:在常规心脏三维CT成像检查中可见国人心脏心尖部心肌存在变薄的影像改变,但未见文献报道。认识该影像征象的相关解剖及影像特征,可为临床相关学科的应用及研究提供客观基础。目的:确定国人心尖区心肌最薄点的存在,测量其厚度及位置关系。方法:解剖学观察12个体外心脏标本并利用游标卡尺测量心尖部最薄点厚度及左室心肌最厚处的厚度。选取2009-01/12在厦门大学附属中山医院CT室进行检查的69例无明确心脏疾患患者的三维CT资料,利用三维成像技术显示心尖部结构。测量心尖最薄点、左室心肌最厚处的厚度及心尖最薄点至冠状动脉前降支的距离。结果与结论:解剖学观察显示体外心脏标本心尖部存在心肌变薄区,厚度为(1.74±0.32)mm,左室心肌最厚处为(13.07±1.48)mm;三维CT可清楚显示心尖部心肌最薄区,厚度为(1.27±0.31)mm,左室心肌最厚处为(12.02±1.66)mm;心尖部最薄点到左冠状动脉前降支的距离为(13.70±3.78)mm。统计结果显示解剖学心尖部最薄点厚度与三维CT测量值差异有显著性意义(P<0.05)。结果证实国人心尖区心肌变薄是一种正常解剖结构,标本解剖学及活体三维CT影像学均可清楚显示
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