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Comparing Two Methods for Measuring Soil Bulk Density and Moisture Content 被引量:2
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作者 Jalal D. Jabro William B. Stevens William M. Iversen 《Open Journal of Soil Science》 2020年第6期233-243,共11页
<span style="font-family:Verdana;">Soil bulk density and moisture content are dynamic properties that vary with changes in soil and field conditions and have many agricultural, hydrological and environ... <span style="font-family:Verdana;">Soil bulk density and moisture content are dynamic properties that vary with changes in soil and field conditions and have many agricultural, hydrological and environmental implications. The main objective of this study was to compare between a soil core sampling method (core) and the CPN MC-3 Elite<span style="white-space:nowrap;"><sup>TM</sup></span> nuclear gauge method (radiation) for measuring bulk density (<span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"></span><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>ρ<sub>B</sub></i></span></span></i></span>) and volumetric moisture content (<span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>θ<span style="font-size:10.9091px;">v</span></i></span></span></i></span>) in a clay loam soil. Soil <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>ρ<sub>B</sub></i></span></span></i></span> and <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"></span><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>θ<span style="font-size:10.9091px;">v</span></i></span></span></i></span> measurements were determined using the core and radiation methods at 0 - 10 and 10 - 20 cm soil depths. The mean values of soil <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>ρ<sub>B</sub></i></span></span></i></span> obtained using the core method (1.454, 1.492 g<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#f7f7f7;"="">·</span>cm<span style="white-space:nowrap;"><sup>&minus;3</sup></span>) were greater than those obtained using the radiation method (1.343, 1.476 g<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#f7f7f7;"="">·</span>cm<span style="white-space:nowrap;"><sup>&minus;3</sup></span>) at the 0 - 10 and 10 - 20 cm depths, respectively. Mean <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>ρ<sub>B</sub></i></span></span></i></span> and <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>θ<span style="font-size:10.9091px;">v</span></i></span></span></i></span> values averaged across both depths (referred to as the 0 - 20 cm depth) measured by the core method were 4.47% and 22.74% greater, respectively, than those obtained by the radiation method. The coefficients of variation (CV) of soil <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"></span><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>ρ<sub>B</sub></i></span></span></i></span> values measured by the core method were lower than the CV values of those measured by the radiation method at both depths;however, the CV’s of <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>ρ<sub>B</sub></i></span></span></i></span> values for both methods were larger at the 0 - 10 cm depth than those measured at the 10 - 20 cm depth. Similarly, the CV values of soil <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>θ<sub>v</sub></i></span></span></i></span> values measured by the core method were lower than the CV values of those measured by the radiation method at both depths. There were significant differences between two methods in terms of <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>ρ<sub>B</sub></i></span></span></i></span> and <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>θ<sub>v</sub></i></span></span></i></span>, with the core method generating greater values than the radiation method at the 0 - 20 cm depth. These discrepancies between the two methods could have resulted from soil compaction and soil disturbance caused by the core and radiation techniques, respectively, as well as by other sources of error. Nevertheless, the core sampling method is considered the most common one for measuring <span style="white-space:nowrap;"><i><span style="font-family:Verdana;white-space:normal;"><span style="white-space:nowrap;"><i>ρ<sub>B</sub></i></span></span></i></span> for many agricultural, hydrological and environmental studies in most soils.</span> 展开更多
关键词 SOIL bulk Density Moisture Content Core method Radiation method
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Bulk MgB2 superconductor with high critical current density synthesized by self-propagating high-temperature synthesis method
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作者 冯旺军 夏天东 +2 位作者 刘天佐 赵文军 魏智强 《Chinese Physics B》 SCIE EI CAS CSCD 2005年第11期2325-2328,共4页
Pure MgB2 bulk samples are successfully synthesized by self-propagatlng hlgh-temperature synthesis (SHS) method. The experiments show that the best preheating temperature is 250℃, the highest Jc values of the prepa... Pure MgB2 bulk samples are successfully synthesized by self-propagatlng hlgh-temperature synthesis (SHS) method. The experiments show that the best preheating temperature is 250℃, the highest Jc values of the prepared MgB2 reach 1.5×10^6A/cm^2 (10K, 0.5T) and 1.7×10^6A/cm^2 (20K, 0T), and the MgB2 particle sizes range from 2 to 5μm. The advantages of this method are that it is simple, economical and suitable for the manufacture of bulk MgB2 materials on industrial scale. 展开更多
关键词 SHS method bulk MgB2 superconductor SUPERCONDUCTIVITY
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Large Ti_3SiC_2 Bulks Fabricated by Infiltration Method
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作者 Shan Di, Yan Guo, Zhou Lian, Li Chengshan, Wang Qingyang, Xiong Xiaomei Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2011年第S3期372-375,共4页
T3SiC2 bulks have been synthesized by infiltrating Si liquid into porous precursor pellets composed of solid Ti and C powders. Silicon pellets were placed at the bottom of the precursor pellets as the liquid source. T... T3SiC2 bulks have been synthesized by infiltrating Si liquid into porous precursor pellets composed of solid Ti and C powders. Silicon pellets were placed at the bottom of the precursor pellets as the liquid source. The starting compositions can be represented by the formula 3Ti + 2C + xSi, where x = 1.0, 1.2, 1.4 and 1.6, respectively. The phase formation and microstructure of the bulks were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results demonstrated that the Ti/C precursor pellet could only react with Si completely when the x value is 1.6. Large, a purity of above 95wt% Ti3SiC2 bulk of up to 50 mm in diameter was obtained by this method. 展开更多
关键词 INFILTRATION method TI3SIC2 bulks Si CONTENT 50 MM in DIAMETER
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Bulk Flow方法分析孔型密封转子动力特性的有效性 被引量:15
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作者 晏鑫 李军 丰镇平 《西安交通大学学报》 EI CAS CSCD 北大核心 2009年第1期24-28,共5页
基于Kleynhans和Childs的两控制容积等温BF(Bulk Flow)模型,通过增加能量方程和理想气体状态方程,建立了理想气体BF方法的数学模型,来预测和分析孔型密封转子在偏心状态下的静力学和动力学特性.由于转子在密封中心附近做微小涡动,故可... 基于Kleynhans和Childs的两控制容积等温BF(Bulk Flow)模型,通过增加能量方程和理想气体状态方程,建立了理想气体BF方法的数学模型,来预测和分析孔型密封转子在偏心状态下的静力学和动力学特性.由于转子在密封中心附近做微小涡动,故可通过采用摄动方法使得NS方程的求解过程得到较大的简化,再通过迭代求解简化后的零阶和一阶摄动方程组,就可以求出孔型密封的流场和动力特性系数.以此为依据发展了相关程序,计算出了不同工况条件下孔型密封的转子动力特性系数与激振频率的关系,通过与已有的实验数据和等温BF模型的计算结果进行对比,验证了理想气体BF模型及相关求解方法的有效性.结果表明:理想气体BF模型的预测结果与实验数据吻合良好,且优于等温BF模型的计算结果,证明了该理想气体BF模型的正确性和计算方法的可靠性.该方法可用于孔型密封动力特性的预测. 展开更多
关键词 孔型密封 bulk Flow方法 两控制容积 转子动力学特性
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造孔方法对钙长石轻质隔热保温陶瓷性能影响
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作者 袁航 占华生 +6 位作者 罗华明 王涵宇 刘景溢 胡思铭 钱坤 邓通 黄朝晖 《耐火与石灰》 2025年第4期28-33,共6页
以纳米碳酸钙、氢氧化铝和800目石英粉为原料制备轻质钙长石隔热保温陶瓷。研究了不同造孔方法(添加烧失剂法和发泡法)对轻质钙长石隔热保温陶瓷力学和热学性能的影响,并对其体积密度、耐压强度和导热系数等性能进行评价。结果表明:1)... 以纳米碳酸钙、氢氧化铝和800目石英粉为原料制备轻质钙长石隔热保温陶瓷。研究了不同造孔方法(添加烧失剂法和发泡法)对轻质钙长石隔热保温陶瓷力学和热学性能的影响,并对其体积密度、耐压强度和导热系数等性能进行评价。结果表明:1)通过添加烧失剂法制备的轻质钙长石隔热保温陶瓷的体积密度为0.88~1.09 g/cm^(3),耐压强度为5.28~7.09 MPa,导热系数(300℃)为0.1286~0.1532 W/(m·K);2)通过发泡法制备的轻质钙长石隔热保温陶瓷的体积密度为0.75~1.19 g/cm^(3),耐压强度为3.28~4.79 MPa,导热系数(300℃)为0.0912~0.1176 W/(m·K);3)综合分析通过发泡法添加60%的泡沫在1300℃下制备的轻质钙长石隔热保温陶瓷性能优异,体积密度为0.75 g/cm^(3),耐压强度为3.28 MPa,导热系数(300℃)为0.0912 W/(m·K)。 展开更多
关键词 轻质钙长石隔热陶瓷 烧失法 发泡法 体积密度 耐压强度 导热系数
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前沿科研成果融入中药化学综合实验教学——人参皂苷Re分子印迹聚合物制备
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作者 林雅立 徐文洁 +4 位作者 莫金玉 唐静雯 钟穗茵 蔡佳仲 黄薇 《广东化工》 2025年第12期165-167,178,共4页
采用分子印迹技术制备中药人参活性成分人参皂苷Re吸附材料,并将其设计成为中药化学综合实验,以期提高中药化学实验课堂的趣味性,激发学生的积极性和创新精神。本实验以人参皂苷Re为模板分子,4-乙烯苯硼酸(4-VPBA)、甲基丙烯酸(MAA)为... 采用分子印迹技术制备中药人参活性成分人参皂苷Re吸附材料,并将其设计成为中药化学综合实验,以期提高中药化学实验课堂的趣味性,激发学生的积极性和创新精神。本实验以人参皂苷Re为模板分子,4-乙烯苯硼酸(4-VPBA)、甲基丙烯酸(MAA)为功能单体,三羟甲基丙烷三丙烯酸酯(TMPTA)为交联剂,偶氮二异庚腈(ABVN)为催化剂,甲苯为致孔剂,通过本体聚合法制备得到人参皂苷Re共价分子印迹聚合物(MIPs),并利用热力学吸附测试MIPs对中药人参活性成分人参皂苷Re的吸附性能。本实验的实施不仅有助于学生巩固中药活性物质合成的基础知识,同时能加深理解中药药效物质的提取分离技术。此外,实验教学可以帮助学生正确使用实验仪器,组装实验装置,更深入地理解高效液相色谱仪的工作原理和应用。将前沿科研成果融入中药化学综合实验教学的实践,能够显著提升学生在实验细节上的关注度,培养他们科学、精准地表述实验结果的能力,并使他们能够熟练运用中药化学的相关理论知识,来正确指导和阐释实验中所观察到的现象。 展开更多
关键词 前沿科研成果 人参皂苷RE 本体聚合法 综合实验教学
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静电喷雾法制备球形硝基胍工艺的数值模拟与试验验证
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作者 董军 刘磊 +2 位作者 王灵鑫 贺希 冀威 《火炸药学报》 北大核心 2025年第6期513-519,共7页
为了得到堆积密度高的球形硝基胍(NQ)晶体,采用数值模拟与试验结合的方法探究静电喷雾法制备球形NQ的工艺;通过ANSYS有限元软件,研究了不同电压、流速、接受距离下NQ粒径的变化规律,建立了相关关系变化曲线;利用控制变量法研究优化工艺... 为了得到堆积密度高的球形硝基胍(NQ)晶体,采用数值模拟与试验结合的方法探究静电喷雾法制备球形NQ的工艺;通过ANSYS有限元软件,研究了不同电压、流速、接受距离下NQ粒径的变化规律,建立了相关关系变化曲线;利用控制变量法研究优化工艺,并通过实验数据与数值模拟对比验证。结果表明,通过模拟后得到的优化工艺方案为:流速0.14mL/min,电压10kV,接收距离250mm;在优化工艺条件下静电喷雾制备的NQ仅发生物理变化;制备的NQ为球形,平均粒径在5μm左右;与原料相比,球形NQ的活化能和热爆炸临界温度分别提高了14.37kJ/mol和16.31K,热稳定性得到提高;球形NQ的堆积密度为1.332g/cm^(3),相较于原料提升了0.948g/cm^(3),流散性得到明显改善。 展开更多
关键词 应用化学 硝基胍 NQ 静电喷雾法 热安全性 堆积密度
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五唑肼晶体的球形化制备与表征
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作者 严石 陈祥 +2 位作者 金智宇 胡炳成 章冲 《南京理工大学学报》 北大核心 2025年第2期257-264,共8页
为了提高五唑肼(N_(2)H_(5)N_(5))的堆积密度及在使用过程中的安全性,开展了五唑肼晶体的球形化研究,探究溶剂非溶剂法中温度、溶液滴加速度、溶剂和非溶剂体积比以及搅拌速度对五唑肼堆积密度的影响。同时,对最终产物进行了扫描电镜(S... 为了提高五唑肼(N_(2)H_(5)N_(5))的堆积密度及在使用过程中的安全性,开展了五唑肼晶体的球形化研究,探究溶剂非溶剂法中温度、溶液滴加速度、溶剂和非溶剂体积比以及搅拌速度对五唑肼堆积密度的影响。同时,对最终产物进行了扫描电镜(SEM)观察、粒径分析、热重分析以及感度测试等表征实验。研究结果表明,在温度25℃、滴加速度8 mL/min、甲醇与1,4-二氧六环体积比1∶7、搅拌速度400 r/min、以0.1%β-环糊精作为添加剂的条件下,制备得到的五唑肼堆积密度最高,为1.2217 g/cm^(3),其形貌为类球形,平均粒径为36.133μm。球形五唑肼的热分解温度为103.64℃,用BAM标准方法测试其撞击感度为8 J,摩擦感度为54 N。 展开更多
关键词 溶剂非溶剂法 五唑肼 球形化 堆积密度 性能表征
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超高层基础大体积混凝土裂缝成因分析与控制措施研究 被引量:1
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作者 安云飞 苏道恒 +2 位作者 蔡青法 吕艳斌 曾昭华 《建筑技术开发》 2025年第8期70-73,共4页
因受力需要,超高层基础混凝土普遍为大体积混凝土,大体积混凝土易产生裂缝,裂缝控制不到位时将对结构的承载能力和耐久性产生不良影响。研究结合案例,分析超高层基础大体积混凝土裂缝产生的主要原因,针对性提出多方面的裂缝控制措施,分... 因受力需要,超高层基础混凝土普遍为大体积混凝土,大体积混凝土易产生裂缝,裂缝控制不到位时将对结构的承载能力和耐久性产生不良影响。研究结合案例,分析超高层基础大体积混凝土裂缝产生的主要原因,针对性提出多方面的裂缝控制措施,分析合理的混凝土配合比设计、大体积混凝土的运输方式、合理的施工方法及养护措施、测温降温措施等大体积混凝土的裂缝控制措施。通过这些措施,有效控制了超高层基础大体积混凝土裂缝,提升了基础大体积混凝土结构的质量和耐久性,可为类似工程提供参考。 展开更多
关键词 大体积混凝土 裂缝成因 裂缝控制 分层分块跳仓法
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Air-sea carbon-dioxide flux estimated by eddy covariance method from a buoy observation 被引量:1
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作者 HUANG Yansong SONG Jinbao +1 位作者 WANG Juanjuan FAN Conghui 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2012年第6期66-71,共6页
Precise measurements of the CO2 gas transfer across the air-sea interface provide a better under- standing of the global carbon cycle. The air-sea CO2 fluxes are obtained by the eddy covariance method and the bulk met... Precise measurements of the CO2 gas transfer across the air-sea interface provide a better under- standing of the global carbon cycle. The air-sea CO2 fluxes are obtained by the eddy covariance method and the bulk method from a buoy observation in the northern Huanghai sea. The effects of buoy motion on flux calculated by the eddy covariance method are demonstrated. The research shows that a motion correction can improve the correlation coefficient between the C02 fluxes esti- mated from two different levels. Without the CO2-H20 cross-correlation correction which is termed as PKT correction, the air-sea CO2 fluxes estimated by eddy covariance method using the motion corrected data are nearly an order of magnitude larger than those estimated by the bulk method. After the CO2-H20 cross-correlation correction, some eddy covariance CO2 fluxes indeed become closer to the bulk CO2 flux, whereas some are overcorrected which are in response to small water vapor flux. 展开更多
关键词 air-sea fluxes motion correction bulk carbon-dioxide flux method eddy covariancemethod
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基于西门子PLC的模块化控制在散粮储运自动化中的应用
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作者 许加建 孙成鑫 +2 位作者 王均骞 杨明 石云龙 《现代食品》 2025年第3期1-5,共5页
在实现散粮储运自动化控制过程中,存在着大量的气缸、气阀、传感器、电机等控制对象,运用常规的程序设计方法会出现代码冗余、编程效率低、维护成本高等问题。针对上述问题,提出了运用模块化程序设计方法进行设计的思路,并以双作用气缸... 在实现散粮储运自动化控制过程中,存在着大量的气缸、气阀、传感器、电机等控制对象,运用常规的程序设计方法会出现代码冗余、编程效率低、维护成本高等问题。针对上述问题,提出了运用模块化程序设计方法进行设计的思路,并以双作用气缸为例给出了具体设计步骤。实际应用发现,运用模块化程序设计方法有效降低了代码冗余,提高了编程效率,降低了维护成本。 展开更多
关键词 散粮储运 自动化控制 模块化 程序设计方法
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改性砖混再生粗骨料的性能研究进展
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作者 王阁琳 王晓初 +1 位作者 杨春峰 杨琳琳 《混凝土与水泥制品》 2025年第7期110-115,119,共7页
综述了砖混再生粗骨料(MRCA)的基本性能(吸水率、压碎指标、表观密度)、分级分类建议以及改性方法(物理改性、化学改性、微生物诱导碳酸盐沉淀技术),分析了改性机理,指出了现有改性方法在实际应用中存在的问题,并对MRCA的改性方法及改性... 综述了砖混再生粗骨料(MRCA)的基本性能(吸水率、压碎指标、表观密度)、分级分类建议以及改性方法(物理改性、化学改性、微生物诱导碳酸盐沉淀技术),分析了改性机理,指出了现有改性方法在实际应用中存在的问题,并对MRCA的改性方法及改性MRCA在实际工程中的应用前景进行了展望。 展开更多
关键词 建筑和拆除废物(C&DW) 砖混再生粗骨料(MRCA) 分级分类 改性方法 吸水率 压碎指标 表观密度
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First principles study on the charge density and the bulk modulus of the transition metals and their carbides and nitrides 被引量:2
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作者 李承斌 黎明锴 +2 位作者 尹东 刘福庆 范湘军 《Chinese Physics B》 SCIE EI CAS CSCD 2005年第11期2287-2292,共6页
A first principles study of the electronic properties and bulk modulus (B0) of the fcc and bcc transition metals, transition metal carbides and nitrides is presented. The calculations were performed by plane-wave ps... A first principles study of the electronic properties and bulk modulus (B0) of the fcc and bcc transition metals, transition metal carbides and nitrides is presented. The calculations were performed by plane-wave pseudopotential method in the framework of the density functional theory with local density approximation. The density of states and the valence charge densities of these solids are plotted. The results show that B0 does not vary monotonically when the number of the valence d electrons increases. B0 reaches a maximum and then decreases for each of the four sorts of solids. It is related to the occupation of the bonding and anti-bonding states in the solid. The value of the valence charge density at the midpoint between the two nearest metal atoms tends to be proportional to B0. 展开更多
关键词 density functional theory plane-wave pseudopotential method bulk modulus chargedensity
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Simulation of bulk metal forming processes using one-step finite element approach based on deformation theory of plasticity 被引量:2
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作者 王鹏 董湘怀 傅立军 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第2期276-282,共7页
The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/stra... The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method. 展开更多
关键词 bulk metal forming plastic deformation theory finite element method one-step forward simulation rigid-plastic materials
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The Improvement of Bulk-Heterojunction Order in Polymer Photovoltaic Device
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作者 YUAN Dan CHEN Zhi-jian XIAO Li-xin MU Li-ping QU Bo GONG Qi-huang 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2011年第12期3175-3179,共5页
The blend morphology and vertical arrangement are critical to the performance of organic bulk-heterojunction photovoltaic devices.In the present paper,the authors proposed a new annealing method that controls the blen... The blend morphology and vertical arrangement are critical to the performance of organic bulk-heterojunction photovoltaic devices.In the present paper,the authors proposed a new annealing method that controls the blend morphology and vertical arrangement of two materials by means of simultaneously applying external electrical field and violet irradiation on the active layer of poly(3-hexylthiophene) (P3HT) and -phenyl C61-butyric acid methyl ester(PCBM) during annealing process.By using this annealing method,the power conversion efficiency increased by 36%,which was caused by vertical phased-separated blend of crystalline P3HT and PCBM and better charge extraction of electrodes.X-ray photoelectron spectroscopy(XPS) was measured to prove more fullerene derivatives at the organic/cathode interfaces by using this annealing method.The X-ray diffraction(XRD) analysis and UV-Vis absorption spectrum analysis also revealed more ordered polymer crystallization. 展开更多
关键词 Polymer photovoltaic device bulk-HETEROJUNCTION Annealing method
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急倾斜薄矿体采场围岩及假底应力分布规律研究 被引量:3
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作者 李华 荣辉 +1 位作者 何荣兴 张星宇 《现代矿业》 CAS 2024年第4期182-186,共5页
急倾斜极薄矿脉是有色、黄金矿山常见的矿体形态,多采用人工假底的留矿法或削壁充填法回采,研究采动过程中围岩和人工假底的受力分布对于设计假底参数和安全开采具有重要意义。以某金矿削壁充填采场为工程背景,模拟研究了人工假底及围... 急倾斜极薄矿脉是有色、黄金矿山常见的矿体形态,多采用人工假底的留矿法或削壁充填法回采,研究采动过程中围岩和人工假底的受力分布对于设计假底参数和安全开采具有重要意义。以某金矿削壁充填采场为工程背景,模拟研究了人工假底及围岩采动过程中应力变化规律。上、下盘围岩采动后最大主应力和最小主应力减小,回采区域顶板应力集中。假底中心处垂直压力最小,越靠近上、下盘边壁垂直压力增加,随着采高增加,假底各部位的垂直压力增加,最后呈收敛趋势。人工假底主要是剪应力破坏,假底破坏主要是上、下盘高水平应力未作用在同一轴线而产生的剪应力造成的。根据散体侧压力和采动应力变化规律,提出在采场内每隔10m利用混凝土铺底,增加人工假底中混凝土强度及垂直方向的配筋,提高假底抗剪强度,从而提高深部采场回采的安全性和人工假底的稳固性。 展开更多
关键词 急倾斜薄矿体 人工假底 削壁充填法 散体压力
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Selection of logging-based TOC calculation methods for shale reservoirs:A case study of the Jiaoshiba shale gas field in the Sichuan Basin
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作者 Huang Renchun Wang Yan +2 位作者 Cheng Sijie Liu Shuai Cheng Li 《Natural Gas Industry B》 2015年第2期155-161,共7页
Various methods are available for calculating the TOC of shale reservoirs with logging data, and each method has its unique applicability andaccuracy. So it is especially important to establish a regional experimental... Various methods are available for calculating the TOC of shale reservoirs with logging data, and each method has its unique applicability andaccuracy. So it is especially important to establish a regional experimental calculation model based on a thorough analysis of their applicability.With the Upper Ordovician Wufeng Fm-Lower Silurian Longmaxi Fm shale reservoirs as an example, TOC calculation models were built by useof the improved DlgR, bulk density, natural gamma spectroscopy, multi-fitting and volume model methods respectively, considering the previousresearch results and the geologic features of the area. These models were compared based on the core data. Finally, the bulk density method wasselected as the regional experimental calculation model. Field practices demonstrated that the improved DlgR and natural gamma spectroscopymethods are poor in accuracy;although the multi-fitting method and bulk density method have relatively high accuracy, the bulk density methodis simpler and wider in application. For further verifying its applicability, the bulk density method was applied to calculate the TOC of shalereservoirs in several key wells in the Jiaoshiba shale gas field, Sichuan Basin, and the calculation accuracy was clarified with the measured dataof core samples, showing that the coincidence rate of logging-based TOC calculation is up to 90.5%-91.0%. 展开更多
关键词 Sichuan Basin Jiaoshiba gas field Shale reservoir Total organic carbon(TOC) Logging data bulk density method DlgR method Natural gamma spectroscopy Multi-fitting
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Preparation and Characterization of Copper-Nickel Bulk Nanocrystals
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作者 吴小强 TANG Yongjian +3 位作者 WANG Lan AN Xuguang YI Zao 孙卫国 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第3期606-611,共6页
Copper-nickel nanoparticle was directly prepared by flow-levitation method (FL) and sintered by vacuum sintering of powder (VSP) method. Several characterizations, such as transmission electron microscopy (TEM),... Copper-nickel nanoparticle was directly prepared by flow-levitation method (FL) and sintered by vacuum sintering of powder (VSP) method. Several characterizations, such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), differential thermal analysis (DTA), and energy-dispersive X-ray spectroscopy (EDX) were used to investigate the prepared nanostructures. The results of the study show that FL method could prepare high purity Cu-Ni nanocrystals of uniform spheres with size distribution between 20 and 90 nm. After sintering the bulk nanocrystalline copper-nickel has obvious thermal stability and the surface Webster hardness increases with the rising sintering temperature. At the temperature of 900 ℃, the specimen shows higher surface Webster hardness, which is about two times of traditional materials. When the sintering temperature arrives at 1 000 ℃ the relative density of bulk nanocrystals can reach 97.86 percent. In this paper, the variation tendency of porosity, phase and particles size of bulk along with the changing of sintering temperature have been studied. 展开更多
关键词 bulk nanocrystals flow-levitation method surface Webster hardness vacuum sintering of powder
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Preparation and thermal stability of Pd_(40.5)Ni_(40.5)Si_xP_(19-x) bulk metallic glasses
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作者 Yang Li Yao-cen Wang Ke-fu Yao 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2010年第2期204-207,共4页
With the addition of Si to replace some P,Pd40.5Ni40.5SixP19-x(x=0,2.5,5,9.5,14,and 19 in atomic number fraction) bulk glassy samples with the diameter of about 5 mm were successfully prepared by use of flux treatme... With the addition of Si to replace some P,Pd40.5Ni40.5SixP19-x(x=0,2.5,5,9.5,14,and 19 in atomic number fraction) bulk glassy samples with the diameter of about 5 mm were successfully prepared by use of flux treatment and water quenching technology.With the increase of Si content,the glass forming ability of Pd40.5Ni40.5Si-xP19-x increases first for low Si content and then decreases for high Si content (Si≥9.5at%).The Pd40.50Ni40.5Si5P14 glassy alloy possesses the largest supercooled liquid region△T of 119 K,the largest reduced glass transition temperature of 0.621,and the largestγparameter of 0.460,indicating that this glassy alloy possesses very large glass forming ability and very high thermal stability. 展开更多
关键词 bulk metallic glass flux method glass forming ability water quenching thermal stability
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变容积密集烤房的CFD分析与试验研究 被引量:3
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作者 叶大鹏 沈碧河 +2 位作者 张炳辉 黄俊炜 谢立敏 《中国农机化学报》 北大核心 2024年第3期90-95,125,共7页
为保障密集烤房装烟密度,降低烘烤的能源消耗,研发一套适用于密集烤房的变容积系统。在完成变容积装置的设计后,基于CFD方法模拟分析装置与烟叶的不同距离对烤房内部气体分布均匀性的影响。通过烘烤试验获取实际烘烤数据,对模拟值加以... 为保障密集烤房装烟密度,降低烘烤的能源消耗,研发一套适用于密集烤房的变容积系统。在完成变容积装置的设计后,基于CFD方法模拟分析装置与烟叶的不同距离对烤房内部气体分布均匀性的影响。通过烘烤试验获取实际烘烤数据,对模拟值加以验证。试验结果表明:当隔板与烟叶距离为0 cm时,流速不均匀系数Kv为0.40,温度不均匀系数Kt为0.41,距离为10 cm时,Kv=0.41,Kt=0.43;距离为20 cm时,Kv=0.42,Kt=0.49。装烟区9个测量点的温度模拟值与实测值基本吻合,误差在6%以内。变容积烤房在装烟量为一半时,相比常规烤房的燃料消耗可节约13.4%。研究结果表明:当隔板与烟叶距离为0 cm时烤房内部的气体分布最均匀;CFD模型与数值模拟结果具有可靠性;变容积装置具有较好的保温效果,可保证装烟密度,降低烤烟能耗。 展开更多
关键词 密集烤房 变容积 CFD方法 数值模拟
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