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文章速递Study on the Plugging System of the Lower Ancient High Loss Zone in Changqing Gas Field 认领
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作者 Yan Gao Zuwen Wang +2 位作者 Xiuli Shao Dichen Tan Erping Liu 《长江油气:英文版》 2021年第1期1-12,共12页
At present, in the workover operations of old gas wells in the Changqing Gas Field, due to years of exploitation in the production layer, pressure deficits, and general leakage during the well killing, the well must b... At present, in the workover operations of old gas wells in the Changqing Gas Field, due to years of exploitation in the production layer, pressure deficits, and general leakage during the well killing, the well must be plugged before the well can be killed. In particular, the fracture-cavity type fractures of the lower paleocarbonate reservoirs have serious leakage. Traditional plugging materials and traditional plugging materials and methods have some limitations in dealing with leakage problems. Therefore, a composite plugging system using polymer solution as the base carrier fluid, multi-particle size rigid particles, expandable particles and modified fibers is developed. Its formula is: water + 2% polyacrylamide + 0.1% N, N-methylene bisacrylamide polymer gel is the base carrier fluid;the formulation of the particle plugging agent was continuously optimized through the CDL-II high temperature and high pressure dynamic and static plugging ability to plug the core. The final formulation of the plugging agent is: 1) 20% rigid particles (5 mm, 1 mm, 0.5 mm CCP-3 ratio 4:2:1) + 1% 3 mm expanded particles SMK-1 + 1% 1 ~ 2 mm fiber SRXW-10;2) 20% rigid particles (3 mm, 0.1 mm, 0.05 mm CCP-3 ratio 3:2:1) + 1% 3 mm expanded particles SMK-1 + 1% 1 ~ 2 mm fiber SRXW-10. The water swelling multiples of the granular plugging agent in salt water are all above 7 times, which meets the requirements of leak-proof plugging operations under high salinity;3% HCl is selected as the gel breaker, and the plugging system has a gel breaking rate of 95%;through the water plugging and profile control experimental system, the sand-filled pipe is used to simulate the plugging effect under high temperature and high pressure, and the plugging system can be sealed for 5 days at a high temperature of 110°C and a high pressure of 20 MPa to achieve a good plugging of the formation. It is expected that the developed plugging system has a good application prospect in future workover operations. 展开更多
关键词 Lower Ancient High Loss Layer Plugging Gel Particle Plugging Agent Gel Breaking Performance Plugging Performance
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文章速递Experimental Study on Performance and Combustion Analysis of a Diesel Engine Fueled with Diesel and Jatropha Oil Blended with Heptane 认领
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作者 Yomi Woro Gounkaou Tizane Daho +5 位作者 Ali Diane Gilles Vaitilingom Bruno Piriou Jeremy Valette Oumar Sanogo Antoine Béré 《能源与动力工程(英文)》 2021年第1期1-16,共16页
This work focuses on blending Jatropha oil with diesel fuel and heptane to improve its physico-chemical characteristics for production of blends and their use as fuel in a diesel engine. The influence of the heptane c... This work focuses on blending Jatropha oil with diesel fuel and heptane to improve its physico-chemical characteristics for production of blends and their use as fuel in a diesel engine. The influence of the heptane content was evaluated by comparing the results obtained from the engine (performance and combustion parameters) with those of the diesel fuel and straight Jatropha oil. The results obtained show an improvement in engine performance especially at low loads. Specifically, a reduction in the specific fuel consumption of the engine is obtained when the heptane content in the mixture is around 10% compared to that obtained with pure Jatropha oil. The best results were obtained with the blend containing 70% Jatropha oil, 20% diesel fuel and 10% heptane (J70G20H10). Overall engine efficiency and exhaust gas temperatures are comparable for all fuels tested. Engine combustion parameters are improved with J70G20H10. The results obtained with J70G20H10 are close to those of the engine operating on diesel fuel. The cyclic dispersion is low with coefficients of variation of the indicated mean effective pressure (COV<sub>IMEP</sub>) whose values are less than 10%. The lowest values of the COV<sub>IMEP</sub> are obtained with the blend J70G20H10. 展开更多
关键词 Diesel Engine Jatropha Oil Heptane Blends Engine Performance Cyclic Dispersion
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文章速递Highway Concrete Guardrail Lifting Scheme and Safety Performance Verification 认领
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作者 Ronggui Zhou Yidan Xie Jiangang Qiao 《交通科技期刊(英文)》 2021年第1期1-13,共13页
In order to achieve the old fence of reuse, improve the safety performance of guardrail, barrier structure does not meet the requirements, make full use of the old concrete guardrail on the basis of heightening, throu... In order to achieve the old fence of reuse, improve the safety performance of guardrail, barrier structure does not meet the requirements, make full use of the old concrete guardrail on the basis of heightening, through computer simulation experiment were analyzed, and optimization design, through the real car collision test, make the concrete guardrail after heightening structure satisfies the requirement of </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">safety performance of current specification. The results show that the protective performance of the two guardrail schemes meets the requirements of the current guardrail evaluation standards through the computer simulation experiment. Through the optimized design of scheme 1, the actual car crash test proves that the enhanced structure of Minhua TYPE II concrete guardrail can meet the requirements of safety performance evaluation. The research results provide an important basis for the transformation of </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">guardrail and the revision of the current design of expressway in China. 展开更多
关键词 Concrete Guardrail Scheme Optimization Simulation Real Vehicle Collision Safety Performance
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文章速递Effects of Seed Pretreatment on Germination, Growth and Yield of <i>Momordica charantia</i>L. 认领
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作者 Samba Balde Nicolas Cyrille Ayessou +4 位作者 Antoine Sambou Khadim Niane Papa Guedel Faye Mady Cisse Codou Mar Diop 《农业科学(英文)》 2021年第1期39-57,共19页
<em>Momordica charantia</em> is a plant species widely used in food and traditional medicine. However, the germination techniques and the performances of <em>M. charantia</em> are poorly unders... <em>Momordica charantia</em> is a plant species widely used in food and traditional medicine. However, the germination techniques and the performances of <em>M. charantia</em> are poorly understood by the populations. This study aims to better understand the germination, growth and development characteristics, and yield of <em>M. charantia</em>. Three pretreatments of the seeds are used for the shortening of the pre-germination period: soaking the seeds in tap water for 24 hours (batch 2), in hot water at 80<span style="white-space:nowrap;">&#730;</span>C (batch 3), for 24 hours and in the boiling water at 100<span style="white-space:nowrap;">&#730;</span>C for 24 hours (batch 4). A control without soaking (batch 1) was also carried out. The seeds were sown in plastic boxes in the laboratory with sterile sand and directly in the nursery in polyethylene sleeves. The influence of the light factor (light and dark) and watering frequency (every day and every two days) on the growth and yield parameters was evaluated respectively in the laboratory and in the nursery. Germination, growth and yield parameters were determined. The results show that the light and frequency of watering factors have no influence (p > 0.05) on the rate and duration of seed germination unlike pretreatments. Thus, Batch1 and 2 exhibit significantly higher germination rates (70% ± 16%) than Lots 3 and 4 (21% ± 15%) in the laboratory and in the nursery. On the other hand in terms of germination time, batch 3 and 4 displayed shorter durations (14 days) than those batch1 and 2 (23 days). Growth parameters and yield (fruit and seeds) are strongly influenced by watering frequency, unlike pretreatments which only affect yield. Growth and yield parameters are significantly higher with daily watering than daily watering. Ultimately, this study showed that pretreatments have an influence on the duration and rate of germination as well as the frequency of watering on the performance of <em>M. charantia</em>. 展开更多
关键词 Momordica charantia Germination Performance Yield
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文章速递Effects of Guar (<i>Cyamopsis tetragonoloba</i>) Residues on the Performance and Nutrients Digestibility in Finishing Awassi Lambs 认领
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作者 Jamal Abo Omar Ahmed Zaazaa +3 位作者 Maen Sheqwarah Bassam Abu Shanab Wael Qaisi Jehad Abdallah 《动物科学期刊(英文)》 2021年第1期96-104,共9页
The nutritive quality of guar (<i></span><i><span style="font-family:Verdana;">Cyamopsis tetragonoloba</span></i><span style="font-family:Verdana;"></i&... The nutritive quality of guar (<i></span><i><span style="font-family:Verdana;">Cyamopsis tetragonoloba</span></i><span style="font-family:Verdana;"></i></span><span style="font-family:Verdana;">) residues (GR) was investigated and the effects of partial replacement of wheat straw by GR on nutrients intake, digestibility, and growth performance. Twenty four male lambs, with average body weight (BW) of 40.3 ± 2.5 kg were divided into three groups. Lambs were fed individually for 104 days with concentrate mixture (18% crude protein) and wheat straw as a total mixed ration. Wheat straw was replaced with 0, 100 and 145 g/kg dry matter guar residues. All rations were isonitrogenous and isocaloric. The fattening trial lasted 104 days</span></span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> At the end of week 10 of the trail</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> a digestion trial was performed using six lambs from each group. The composition of nutrients in the GR was 87%, 8.5%, 56.4% and 40.1% for DM, CP, NDF and ADF, respectively. DM and crude protein (CP) intake were not affected by the inclusion of GR</span><span style="font-family:Verdana;">.</span><span style="font-family:""><span style="font-family:Verdana;"> However, neutral detergent fibre (NDF) and acid detergent fibre (ADF) intake were lower in lambs fed GR compared to control lambs. At the end of the experiment, lambs fed 100 and 145 g GR/kg DM diets gained more weight (P < 0.05) than those fed the control diet. The same trend was found for feed con</span><span style="font-family:Verdana;">version (CR). Results from this work suggest</span></span><span style="font-family:Verdana;">ed</span><span style="font-family:Verdana;"> that GR had advantages compa</span><span style="font-family:Verdana;">red to regular roughage (wheat straw) in regard to parameters investigated as well as the significant reduction in fattening diets cost. 展开更多
关键词 Guar Residues Awassi Lambs Performance Nutrients Digestibility
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文章速递Determine the Optimal Density of Nile Tilapia (<i>Oreochromis niloticus</i>) Fingerlings Cultured in Floating Cages 认领
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作者 B. A. El Nouman O. A. Egbal +3 位作者 Y. A. Sana M. S. Anwar A. A. Eman F. A. Yosif 《自然资源(英文)》 2021年第1期1-9,共9页
The objective of the study was to determine the optimal density of fingerlings of the Nile tilapia (<em>Oreochromis niloticus</em>) culture in floating cages with respect to growth performance and to know ... The objective of the study was to determine the optimal density of fingerlings of the Nile tilapia (<em>Oreochromis niloticus</em>) culture in floating cages with respect to growth performance and to know the effect of temperature on growth during the winter period. Tilapia fingerlings (mean weight 8.5 ± 0.36 g) were stocked at densities of 120, 180 and 360 fish/m<sup>3</sup> for 10 weeks. During culture, fish were fed a diet contains 35% protein made of peanut seed, cottonseed, wheat bran, and Sorghum. The results showed that the increase in fish density reduced the final weight of the fish. The percentage of the fish weight increased and reached 111% ± 1.45% in the lowest fish density (120 fish/m<sup>3</sup>), 79% ± 1.87% in the medium density (240 fish/m<sup>3</sup>), and 63% ± 2.03% of high fish density (360 fish/m<sup>3</sup>), therefore the daily growth rate was better in the lowest density. The rate of food conversion ratio was also better in the lowest density with 2.17 ± 0.33, followed by the medium density with 2.79 ± 0.28 and then the highest density with 3.09 ± 0.21. However, the total production in the cage increased with increasing fish density, and the return to the cost of food was better with higher fish density. According to various performance evaluation criteria, it can be concluded that the medium density 240 fish/m<sup>3</sup> is the best for growing Nile tilapia fingerlings in floating cages. It was observed that the growth rates of the three treatments were low due to the decrease in water temperature in most of the study period, which may indicate the useless of culture in cages in the winter season. 展开更多
关键词 Cage Culture Stocking Density Nile Tilapia Fingerlings Growth Performance Sudan
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文章速递Customization and Performance of Service-Oriented Manufacturing Information System: The Mediating Effect of Information System Flexibility 认领
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作者 Peng Niu 《智能信息管理(英文)》 2021年第1期1-30,共30页
The purpose of this paper is to provide empirical evidence for the validity of the relationship between service-oriented manufacturing information system (SMIS) customization and performance from three aspects: data f... The purpose of this paper is to provide empirical evidence for the validity of the relationship between service-oriented manufacturing information system (SMIS) customization and performance from three aspects: data flexibility, process flexibility and system flexibility. We select some questionnaires from the third round of High-performance manufacturing (HPM) data to construct the construct, verify the reliability and validity of the construct, extract principal components, and analyze the mediating effect by using multiple chain linear regression and structural equation model. The results show that SMIS customization has a significant impact on its performance, and this effect works through its flexibility. More specifically, it is the multiple chain mediation effect composed of data flexibility, process flexibility and system flexibility. The importance of SMIS customization and flexibility to the organization is made clear, which helps practitioners understand the internal mechanism that affects SMIS performance, so as to use limited resources to improve system performance. 展开更多
关键词 Service-Oriented Manufacturing Information System Customized Information System Flexibility of Information System Information System Performance Mediating Effect
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一款电动汽车用锂离子电池循环过程中的性能研究 认领
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作者 龚明光 朱强 范恒斌 《时代汽车》 2021年第2期121-123,共3页
以一款市售的40Ah三元离子电池为研究对象,研究其在充放电循环过程一致性的变化、高低温放电性能以及倍率充放电性能。结果表明,随着循环次数的增加,样品的容量一致性变差,低温特性和倍率充电性能变差,而高温放电特性和倍率放电性能基... 以一款市售的40Ah三元离子电池为研究对象,研究其在充放电循环过程一致性的变化、高低温放电性能以及倍率充放电性能。结果表明,随着循环次数的增加,样品的容量一致性变差,低温特性和倍率充电性能变差,而高温放电特性和倍率放电性能基本无衰减。 展开更多
关键词 锂离子电池 循环 性能
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清香型白酒企业质量评价系统指标的分析与思考 认领
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作者 王奋明 《酿酒》 CAS 2021年第1期22-25,共4页
企业的生存和发展依靠的是高效的管理体系,优良的产品和贴心的服务,而精准的评价某一方面的管理效率是企业实现目标的有效手段。质量评价系统是质量管理当中评价管理绩效的关键组成部分,也是体现企业质量管理水平和能力的重要指标。
关键词 质量 质量评价系统 评价指标 绩效
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淡化海砂在沿海水利工程的应用综述 认领
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作者 杨义忠 张松风 《吉林水利》 2021年第1期36-39,共4页
淡化海砂在国内外作为建筑用砂已有80年的历史,取得了良好的应用效果。其物理性能满足建筑用砂的要求,而且具备价格便宜、资源丰富、工艺成熟、环保等优势。通过随机进行的全国部分城市建筑用砂的价格统计分析表明,近年来河砂价格快速攀... 淡化海砂在国内外作为建筑用砂已有80年的历史,取得了良好的应用效果。其物理性能满足建筑用砂的要求,而且具备价格便宜、资源丰富、工艺成熟、环保等优势。通过随机进行的全国部分城市建筑用砂的价格统计分析表明,近年来河砂价格快速攀升,淡化海砂具备较好价格优势,其应用可以能大幅度降低工程造价,具备广泛应用前景,特别适合沿海水利工程的大量应用。 展开更多
关键词 淡化海砂 性能 价格 应用前景
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纳米技术在镁质耐火材料中应用的研究进展 认领
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作者 赵嘉亮 罗旭东 +1 位作者 陈俊红 谢志鹏 《工程科学学报》 EI 北大核心 2021年第1期76-84,共9页
利用纳米技术制备复相镁质耐火材料,不仅可以缓解高温工业对高性能镁质材料的需求,而且又能实现镁质耐火材料的轻质化和多功能化,进而达到提高产品附加值的目的.因此,利用纳米技术制备复相镁质耐火材料具有较高的研究意义.从镁质耐火材... 利用纳米技术制备复相镁质耐火材料,不仅可以缓解高温工业对高性能镁质材料的需求,而且又能实现镁质耐火材料的轻质化和多功能化,进而达到提高产品附加值的目的.因此,利用纳米技术制备复相镁质耐火材料具有较高的研究意义.从镁质耐火材料损毁机制的角度,综述了近年来国内外纳米技术在低碳镁碳质、镁钙质、镁铝质耐火材料中的研究现状和进展,并且分析了纳米技术在镁质耐火材料中的作用机理,最后指出了纳米技术在镁质耐火材料中应用所面临的挑战和发展方向. 展开更多
关键词 纳米技术 低碳镁碳质耐火材料 镁钙质耐火材料 镁铝质耐火材料 性能
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电火花沉积技术研究现状与展望 认领
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作者 张勇 李丽 +5 位作者 常青 王晓明 赵阳 朱胜 徐安阳 高宪伟 《表面技术》 EI CAS 北大核心 2021年第1期150-161,共12页
电火花沉积技术被广泛地应用于零部件表面涂层的制备与损伤的修复。简要介绍了电火花沉积技术的原理,概括了其进行表面强化与修复的优点。系统地讨论了电火花沉积技术主要工艺参数(电压、电容、比沉积时间和氩气流量)对涂层的沉积效率... 电火花沉积技术被广泛地应用于零部件表面涂层的制备与损伤的修复。简要介绍了电火花沉积技术的原理,概括了其进行表面强化与修复的优点。系统地讨论了电火花沉积技术主要工艺参数(电压、电容、比沉积时间和氩气流量)对涂层的沉积效率、形貌、缺陷、组织结构和性能的影响规律,其中热量的输入与释放速率是工艺参数对涂层制备产生影响的关键因素,低能量输入下易获得高性能的涂层,但沉积效率较低。针对电火花沉积技术自身裂纹与孔洞缺陷多、沉积效率低、制备涂层不均匀等问题,介绍了在沉积过程自动化、沉积原理优化、与其他技术复合方面做出的技术改进。其中,通过实现与其他表面强化技术的复合是进一步提高涂层性能的有效方式,将是未来研究的重点内容之一。随后,基于工程实际对高性能涂层的需要,介绍了电火花沉积技术在制备陶瓷、高熵合金、非晶涂层中的应用,电火花沉积技术快热急冷的特点,使其在制备涂层的过程中表现出极佳的细晶、非晶、固溶相形成能力。最后总结了电火花沉积技术存在的问题,并对其未来的发展方向进行了展望。 展开更多
关键词 电火花沉积 涂层 工艺参数 技术改进 应用 性能
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无凸轮式配气型线优化设计及发动机性能仿真研究 认领
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作者 张鹏博 《内燃机与配件》 2021年第1期5-6,共2页
本文基于AVL-boost建立一维发动机仿真模型,对采用无凸轮式配气型线的发动机整机性能进行数值模拟。仿真结果表明:采用无凸轮式配气型线可以根据不同工况灵活调整气门升程及相位,能够有效降低发动机部分负荷工况下的换气损失,改善发动... 本文基于AVL-boost建立一维发动机仿真模型,对采用无凸轮式配气型线的发动机整机性能进行数值模拟。仿真结果表明:采用无凸轮式配气型线可以根据不同工况灵活调整气门升程及相位,能够有效降低发动机部分负荷工况下的换气损失,改善发动机的动力性及燃油经济性,为无凸轮式配气机构的控制应用提供了理论依据。 展开更多
关键词 发动机 无凸轮式配气型线 数值模拟 整机性能
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Numerical investigation of the seismic response of a UHV composite bypass switch retrofitted with wire rope isolators 认领
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作者 Yang Zhenyu Xie Qiang +1 位作者 He Chang Xue Songtao 《地震工程与工程振动:英文版》 SCIE EI 2021年第1期275-290,共16页
An ultra-high voltage(UHV)composite bypass switch(BPS)faces increasing seismic challenges when UHV projects extend to high seismic intensity areas.The UHV composite BPS still generates excessive stress at the bottom s... An ultra-high voltage(UHV)composite bypass switch(BPS)faces increasing seismic challenges when UHV projects extend to high seismic intensity areas.The UHV composite BPS still generates excessive stress at the bottom section although hollow composite insulators with high flexural strength are adopted.Since the standard retrofitting strategy by using stiffer supports cannot reduce stress responses,wire rope isolation is introduced.The optimal design of isolation considers both stress and displacement responses since the slenderness and composite material of insulators contribute to significant displacement.The results show that properly designed isolation can significantly reduce stress without excessive displacement responses.A larger radius configuration helps to improve the applicability of small stiffness isolators under high winds.When the isolation still cannot satisfy the requirement,smaller stiffness isolators with a larger radius,or isolators with increased loops and smaller radius,can be introduced to gain better energy dissipation capacity and effectiveness in response mitigation.Accordingly,a three-step design procedure is proposed to increase the damping force but fix the rotational stiffness of isolation.Hence,the application of wire rope isolation can be extended to UHV composite BPS with a low natural frequency,but conductors with enough redundancy should be used. 展开更多
关键词 UHV composite bypass switch seismic analysis seismic performance upgrading wire rope isolator
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政府会计制度改革和行政事业单位绩效关系分析 认领
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作者 岳苗 《中小企业管理与科技》 2021年第2期188-189,192,共3页
论文首先介绍了我国政府会计的发展历程,在诠释了政府绩效的基础上,从完善行政事业单位绩效评价体系、摸清行政事业单位“家底”和提升行政事业单位管理效率三个层面探讨了政府会计改革对行政事业单位绩效的影响。最后,结合以上分析,提... 论文首先介绍了我国政府会计的发展历程,在诠释了政府绩效的基础上,从完善行政事业单位绩效评价体系、摸清行政事业单位“家底”和提升行政事业单位管理效率三个层面探讨了政府会计改革对行政事业单位绩效的影响。最后,结合以上分析,提出了政府会计制度改革提升我国行政事业单位绩效的对策建议。论文的研究有助于明晰政府会计制度改革和行政事业单位绩效之间的内在关系。 展开更多
关键词 政府会计制度改革 行政事业单位 绩效
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安徽省阜南县县域医共体建设成效分析 认领
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作者 刘雪薇 许寒冰 +1 位作者 崔倩倩 孔杨 《中国医疗管理科学》 2021年第1期14-18,共5页
目的分析总结安徽省阜南县县域医共体实施成效,以期为县域医共体深化改革及其他地区医共体推进提供借鉴。方法收集阜南县历年的住院总费用、县域内外住院分布、住院补偿支出、新农合实际报销比、城乡居民实际住院补偿比等数据及相关政... 目的分析总结安徽省阜南县县域医共体实施成效,以期为县域医共体深化改革及其他地区医共体推进提供借鉴。方法收集阜南县历年的住院总费用、县域内外住院分布、住院补偿支出、新农合实际报销比、城乡居民实际住院补偿比等数据及相关政策文件进行描述性统计分析。结果阜南县县域医共体整体运行状况良好,住院费用增长得到有效控制,患者住院负担减轻,居民"看病贵"得到有力缓解;县域内外就诊结构有待进一步优化,县域内医疗机构整体服务能力有待加强,基层医疗质量有待提高。结论县域医共体改革初期,阜南县县内就诊、基层就诊情况等均显著改善,但持续性不强,后期出现回跌趋势。对此,应积极发挥医保基金的杠杆作用,强化县域内外就医、转诊的引导、筛选与管理,继续加强人才引进和培养力度,并严格督促跟踪问题整改落实情况,切实提高县域内及基层的医疗服务能力,推动阜南县县域医共体建设共心、共管、共利,实现协作共赢。 展开更多
关键词 县域医共体 阜南县 基层医疗机构 医疗服务能力 效果
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Implanted devices: the importance of both electrochemical performance and biological acceptance 认领
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作者 Ashley N.Dalrymple 《中国神经再生研究:英文版》 SCIE CAS 2021年第6期1188-1189,共2页
Neural interfaces can be implanted throughout the body to restore function,including cochlear implants for severe hearing loss,deep brain stimulation for tremor,and spinal cord stimulation for pain.These devices are i... Neural interfaces can be implanted throughout the body to restore function,including cochlear implants for severe hearing loss,deep brain stimulation for tremor,and spinal cord stimulation for pain.These devices are intended to remain implanted and effective for the lifetime of the user,which could be several decades.Device performance and longevity can be impacted by the state of the electrode-tissue interface.Electrochemical performance and tissue reaction to implanted electrodes are important factors to consider when testing novel electrodes and materials,and can facilitate understanding of the reactions at the interface. 展开更多
关键词 STIMULATION performance LIFETIME
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流场沟槽对质子交换膜燃料电池性能的影响 认领
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作者 孟庆然 陈海伦 +1 位作者 田爱华 刘金东 《电源技术》 CAS 北大核心 2021年第1期22-26,共5页
合理的流场结构能够提高燃料电池性能以及燃料的利用率。通过建立新型流场结构,对新型流场的速度矢量、流道内压力分布、阴极氧含量的分布等进行了分析。研究结果表明:在流道内压降合理的情况下,在流道轴线上建立均匀分布、不同数量的... 合理的流场结构能够提高燃料电池性能以及燃料的利用率。通过建立新型流场结构,对新型流场的速度矢量、流道内压力分布、阴极氧含量的分布等进行了分析。研究结果表明:在流道内压降合理的情况下,在流道轴线上建立均匀分布、不同数量的矩形沟槽时,矩形沟槽数N=5为最适宜的沟槽数;在流场中分别加入波浪形沟槽、矩形沟槽和三角形沟槽,对电池性能均有所提高,其中,波浪形沟槽的效果要优于矩形沟槽和三角形沟槽。 展开更多
关键词 流场 沟槽 类型 压降 性能
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小学教育设施空间配置及学区划分绩效研究——基于西安市雁塔区的实证研究 认领
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作者 周晓敏 李志民 谢世雄 《华中建筑》 2021年第1期58-62,共5页
基础教育设施的均衡发展关乎教育质量、教育公平,也是社会和谐的重要保障。该文以西安市雁塔区为例,基于教育设施的宏观空间配置与微观调查问卷,探讨城市快速增长时期基础教育设施空间配置及其学区划分的绩效,研究结果表明:雁塔区现有... 基础教育设施的均衡发展关乎教育质量、教育公平,也是社会和谐的重要保障。该文以西安市雁塔区为例,基于教育设施的宏观空间配置与微观调查问卷,探讨城市快速增长时期基础教育设施空间配置及其学区划分的绩效,研究结果表明:雁塔区现有的小学教育设施空间配置表现出很强的虹吸效应。表现为公办小学校均规模萎缩,民办小学校越来越受到民众的认可,学区划分与学校空间配置存在错位,学生就学距离和就学成本逐步扩大。"学区制"在实现教育普及的同时,其教育质量的差异加大了学生去向的社会分化。 展开更多
关键词 城市小学 教育设施 空间配置 绩效
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真空退火对原位Al2O3/Fe-Cr-Ni增强复合材料性能的影响 认领
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作者 陈畅 张如意 +1 位作者 史思涛 马奋天 《材料工程》 EI CAS 北大核心 2021年第1期89-94,共6页
铁铬镍合金具有良好的高温强韧性和抗蠕变性,被广泛应用于制造航空发动机、工业燃气轮机等设备。利用原位合成和热压烧结工艺制备Al2O3/Fe-Cr-Ni复合材料。为减少脆性相对复合材料性能的影响,将热压烧结试样在1000℃下真空保温2h后退火... 铁铬镍合金具有良好的高温强韧性和抗蠕变性,被广泛应用于制造航空发动机、工业燃气轮机等设备。利用原位合成和热压烧结工艺制备Al2O3/Fe-Cr-Ni复合材料。为减少脆性相对复合材料性能的影响,将热压烧结试样在1000℃下真空保温2h后退火。采用XRD和SEM等测试方法,研究热处理后Al2O3/Fe-Cr-Ni复合材料的微观结构和常温力学性能。结果表明:Al2O3/Fe-Cr-Ni复合材料主要由Fe-Cr-Ni合金相、Fe-Cr相和Al2O3陶瓷增强相组成。热压烧结试样的维氏硬度、抗弯强度和断裂韧度分别为4.16GPa、298.31MPa和8.04MPa·m1/2。经1000℃高温热处理后,复合材料中Fe-Cr相发生奥氏体转变和合金基体晶粒长大,导致硬度下降至2.98GPa。Fe-Cr-Ni合金基体中韧性相含量和基体连续性增加,使该复合材料的抗弯强度和断裂韧度明显上升,其值分别为459.33MPa和12.81MPa·m1/2。 展开更多
关键词 陶瓷颗粒增强金属基复合材料 原位合成 Fe-Cr相 真空退火 性能
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