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Improved hydrogen storage properties of LiBH4 confined with activated charcoal by ball milling
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作者 He Zhou Xin-Hua Wang +2 位作者 Hai-Zhen Liu Shi-Chao Gao Mi Yan 《稀有金属:英文版》 SCIE EI CAS CSCD 2019年第4期321-326,共6页
In order to enhance the hydrogen storage properties of LiBH4,activated charcoal (AC) was used as the scaffold to confine LiBH4 in this paper.Ball milling was used to prepare LiBH4/AC composites.Experimental results sh... In order to enhance the hydrogen storage properties of LiBH4,activated charcoal (AC) was used as the scaffold to confine LiBH4 in this paper.Ball milling was used to prepare LiBH4/AC composites.Experimental results show that dehydrogenation properties of ball-milled LiBH4/AC (LiBH4/AC-BM) are greatly improved compared with that of pristine LiBH4,ball-milled LiBH4 (LiBH4-BM) and hand-milled LiBH4/AC (LiBH4/AC-HM).The onset dehydrogenation temperature of LiBH4 for LiBH4/AC-BM is around 160 ℃,which is 170 ℃ lower than that of pristine LiBH4.At around 400 ℃,LiBH4/AC-BM finishes the dehydrogenation with a hydrogen capacity of 13.6 wt%,which is approximately the theoretical dehydrogenation capacity of pure LiBH4 (13.8 wt%),while the dehydrogenation processes for LiBH4-BM and LiBH4/AC-BM do not finish even when they were heated to 600 ℃.The isothermal dehydriding measurements show that it takes only 15 min for LiBH4/AC-BM to reach a dehydrogenation capacity of 10.1 wt% at 350 ℃,whereas the pristine LiBH4 and the LiBH4/AC-HM release hydrogen less than 1 wt% under the same conditions.The dehydrogenation process and the effect of AC were discussed. 展开更多
关键词 HYDROGEN STORAGE properties HYDROGEN STORAGE materials Lithium BOROHYDRIDE ACTIVATED charcoal
Carbon storage of a subtropical forest ecosystem: a case study of the Jinggang Mountain National Nature Reserve in southeastern China 预览
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作者 Jiping Zhang Linbo Zhang +2 位作者 Haiguang Hao Chunlan Liu Hui Wang 《林业研究:英文版》 CAS CSCD 2019年第3期1011-1021,共11页
The carbon cycle of forest ecosystems plays a key role in regulating CO2 concentrations in the atmosphere. Research on carbon storage estimation of forest ecosystems has become a major research topic. However, carbon ... The carbon cycle of forest ecosystems plays a key role in regulating CO2 concentrations in the atmosphere. Research on carbon storage estimation of forest ecosystems has become a major research topic. However, carbon budgets of subtropical forest ecosystems have received little attention. Reports of soil carbon storage and topographic heterogeneity of carbon storage are limited. This study focused on the Jinggang Mountain National Nature Reserve as an example of a mid-subtropical forest and evaluated soil and vegetation carbon storage by field sampling combined with GIS, RS and GPS technology. We classified the forest into nine forest types using ALOS high-resolution remote sensing images. The evergreen broad-leaved forest has the largest area, occupying 26.5% of the total area, followed by coniferous and broad-leaved mixed forests and warm temperate coniferous forest, occupying 24.2 and 22.9%, respectively. The vegetation and soil carbon storage of the whole forest ecosystem were 1,692,344 and 5,514,707 t, with a carbon density of 7.4 and 24.2 kg/m^2, respectively, which suggests that the ecosystem has great carbon storage capacity. The topographic heterogeneity of the carbon storage was also analysed. The largest vegetation storage and soil storage is at 700–800 and 1000–1100 m, respectively. The vegetation carbon storage is highest in the southeast, south and southwest. 展开更多
关键词 Vegetation CARBON STORAGE Soil CARBON STORAGE Mid-subtropical forest ecosystem Jinggang MOUNTAIN National Nature Reserve
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1980s-2010s中国陆地生态系统土壤碳储量的变化
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作者 徐丽 于贵瑞 何念鹏 《地理学报:英文版》 SCIE CSCD 2019年第1期49-66,共18页
Soil stores a large amount of the terrestrial ecosystem carbon(C) and plays an important role in maintaining global C balance. However, very few studies have addressed the regional patterns of soil organic carbon(SOC)... Soil stores a large amount of the terrestrial ecosystem carbon(C) and plays an important role in maintaining global C balance. However, very few studies have addressed the regional patterns of soil organic carbon(SOC) storage and the main factors influencing its changes in Chinese terrestrial ecosystems, especially using field measured data. In this study, we collected information on SOC storage in main types of ecosystems(including forest, grassland, cropland, and wetland) across 18 regions in China during the 1980 s(from the Second National Soil Survey of China, SNSSC) and the 2010 s(from studies published between 2004 and 2014), and evaluated its changing trends during these 30 years. The SOC storage(0–100 cm) in Chinese terrestrial ecosystems was 83.46 ± 11.89 Pg C in the 1980 s and 86.50 ± 8.71 Pg C in the 2010 s, and the net increase over the 30 years was 3.04 ± 1.65 Pg C, with an overall rate of 0.101 ± 0.055 Pg C yr–1. This increase was mainly observed in the topsoil(0–20 cm). Forests, grasslands, and croplands SOC storage increased 2.52 ± 0.77, 0.40 ± 0.78, and 0.07 ± 0.31 Pg C, respectively, which can be attributed to the several ecological restoration projects and agricultural practices implemented. On the other hand, SOC storage in wetlands declined 0.76 ± 0.29 Pg C, most likely because of the decrease of wetland area and SOC density. Combining these results with those of vegetation C sink(0.100 Pg C yr–1), the net C sink in Chinese terrestrial ecosystems was about 0.201 ± 0.061 Pg C yr–1, which can offset 14.85%–27.79% of the fossil fuel C emissions from the 1980 s to the 2010 s. These first estimates of soil C sink based on field measured data supported the premise that China’s terrestrial ecosystems have a large C sequestration potential, and further emphasized the importance of forest protection and reforestation to increase SOC storage capacity. 展开更多
关键词 Chinese TERRESTRIAL ECOSYSTEMS CHANGE storage soil ORGANIC carbon
动态温湿度条件下糙米主要储藏品质指标变化 预览
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作者 刘欣 姚远航 +3 位作者 陈文若 顾佳缘 王琰 陈银基 《食品科学》 EI CAS CSCD 北大核心 2019年第3期245-250,共6页
目的:本实验通过研究温湿度动态变化条件下糙米储藏过程中主要生理生化指标的变化,为优化糙米安全储藏条件提供基础数据。方法:将初始水分质量分数分别为15%、17%、19%和21%的糙米,分别在低温动态组(L组)、中温动态组(M组)、高温动态组(... 目的:本实验通过研究温湿度动态变化条件下糙米储藏过程中主要生理生化指标的变化,为优化糙米安全储藏条件提供基础数据。方法:将初始水分质量分数分别为15%、17%、19%和21%的糙米,分别在低温动态组(L组)、中温动态组(M组)、高温动态组(H组)3种不同温湿度动态条件下模拟储藏240d,观测糙米发芽率、脂肪酸值、过氧化氢酶活力等主要品质指标和低场核磁共振水分迁移规律的变化。结果:在240d的储藏过程中,随着储藏时间的延长,发芽率、过氧化氢酶活力呈显著下降趋势,脂肪酸值呈先上升后下降的趋势,糙米品质发生劣变。初始水分质量分数高的糙米其自由水的质量分数要高于初始水分质量分数低的糙米;高温会引起水分迁移混乱,吸附水向自由水迁移,自由水质量分数升高。水分质量分数越高、温度越高,糙米就越容易发生霉变变质。储藏温度对发芽率、脂肪酸值、过氧化氢酶活力有显著影响,初始水分质量分数对发芽率、脂肪酸值有显著影响。结论:初始水分质量分数和储藏温度对糙米的品质特性影响显著。为防止糙米发生品质劣变,正常水分(质量分数15%)和偏高水分(质量分数17%、19%)的糙米安全储藏期为120d,低温或中温可以延长正常水分糙米储藏期至180d。 展开更多
关键词 糙米 储藏 温湿度动态变化 储藏特性
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一种基于HDD-SSD混合的Mesos存储优化方法 预览
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作者 刘文斌 胡亮青 +3 位作者 张汉林 薛逸君 卢煜 陈宁江 《广西大学学报:自然科学版》 CAS 北大核心 2019年第2期433-439,共7页
在分析Mesos持久化存储原理的基础上,提出一种基于HDD-SSD混合存储的Mesos系统持久化存储优化方案。它为了解决HDFS频繁读写带来的I/O性能问题,将HDD-SSD混合存储的HDFS作为Mesos持久化层,并对内存冷页面迁出策略进行了优化。实验结果表... 在分析Mesos持久化存储原理的基础上,提出一种基于HDD-SSD混合存储的Mesos系统持久化存储优化方案。它为了解决HDFS频繁读写带来的I/O性能问题,将HDD-SSD混合存储的HDFS作为Mesos持久化层,并对内存冷页面迁出策略进行了优化。实验结果表明,所提出的方法不仅可以提高基于Mesos的系统I/O性能,而且能保证SSD的利用率,节省SSD的成本开销。 展开更多
关键词 存储 优化 混合存储 持久化
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Design and Operational Strategy Research for Temperature Control Systems of Isothermal Compressed Air Energy Storage Power Plants
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作者 FU Hao JIANG Tong +1 位作者 CUI Yan LI Bin 《热科学学报:英文版》 SCIE EI CAS CSCD 2019年第2期204-217,共14页
Energy storage technology is critical for intelligent power grids. It has great significance for the large-scale integration of new energy sources into the power grid and the transition of the energy structure. Based ... Energy storage technology is critical for intelligent power grids. It has great significance for the large-scale integration of new energy sources into the power grid and the transition of the energy structure. Based on the existing technology of isothermal compressed air energy storage, this paper presents a design scheme of isothermal compressed air energy storage power station, which uses liquid to compress air, hydraulic piston to transfer potential energy, hydraulic turbine to generate electricity at constant pressure, and liquid occupancy to store the gas at constant pressure. Then the technical features and control strategies of its internal temperature control subsystem are studied, and the mathematical model is constructed. A hierarchical relay operation is put forward to address the actual construction and operational requirements of compressed air energy storage power plants. Finally, through physical platform experiments and MATLAB simulation, the feasibility of the design is validated. 展开更多
关键词 HIERARCHICAL RELAY operation ISOTHERMAL compression compressed air ENERGY STORAGE power PLANT ENERGY STORAGE
杯装保健酒外壁防霉处理研究 预览
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作者 谢素琴 《粮食科技与经济》 2019年第2期59-62,共4页
本文研究了杯装保健酒(以虫草巴戟酒为例)在储藏过程中的霉菌污染问题,从各种表面活性剂中,筛选出十二烷基甜菜碱(BS-12,十二烷基二甲基胺乙内酯),采用0.5%~1.1%的BS-12清洗液,可有效防止杯装虫草巴戟酒酒杯外壁被霉菌污染。其中采用0.9... 本文研究了杯装保健酒(以虫草巴戟酒为例)在储藏过程中的霉菌污染问题,从各种表面活性剂中,筛选出十二烷基甜菜碱(BS-12,十二烷基二甲基胺乙内酯),采用0.5%~1.1%的BS-12清洗液,可有效防止杯装虫草巴戟酒酒杯外壁被霉菌污染。其中采用0.9%的BS-12清洗液,浸泡包装好的杯装虫草巴戟酒15min,为有效的防霉处理措施。 展开更多
关键词 防霉措施 十二烷基甜菜碱 杯装虫草巴戟酒 储藏
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空间信息网络分布式存储方案研究 预览
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作者 张平 赵晶 +2 位作者 虞志刚 薛斯达 陆洲 《中国电子科学研究院学报》 北大核心 2019年第3期256-264,共9页
随着空间组网和信息技术的发展,传统的卫星信息系统开始朝着网络化的空间信息网络演进,并具备了星上信息处理和存储的能力。为此,本文提出了一种基于空间分布式存储的空间信息系统方案。与基于地面存储的信息系统相比,通过在空间引入存... 随着空间组网和信息技术的发展,传统的卫星信息系统开始朝着网络化的空间信息网络演进,并具备了星上信息处理和存储的能力。为此,本文提出了一种基于空间分布式存储的空间信息系统方案。与基于地面存储的信息系统相比,通过在空间引入存储资源,该方案在信息获取时效性和空间带宽资源效率方面有明显提升。仿真结果显示,空间信息存储方案相比地面存储方案,信息的平均接收时间从424毫秒缩短到4. 4毫秒,而空间带宽资源消耗节省了将近99%。 展开更多
关键词 空间信息网络 分布式 存储 复制 编码
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不同强度脉冲强光对鲜香菇保鲜效果的影响 预览
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作者 戚向阳 周婷婷 曹少谦 《农业工程学报》 EI CAS CSCD 北大核心 2019年第3期287-293,共7页
为探讨脉冲强光处理对采后食用菌保鲜效果的影响,该试验以新鲜香菇为原料,研究了不同强度(28.8、48.0、67.2mJ/cm^2)脉冲照射后的香菇在25℃保藏期间感官品质、生理指标、衰老指标及营养品质的变化。结果表明,脉冲强光处理在一定程度上... 为探讨脉冲强光处理对采后食用菌保鲜效果的影响,该试验以新鲜香菇为原料,研究了不同强度(28.8、48.0、67.2mJ/cm^2)脉冲照射后的香菇在25℃保藏期间感官品质、生理指标、衰老指标及营养品质的变化。结果表明,脉冲强光处理在一定程度上能维持香菇的色泽和风味,显著延缓保藏过程中香菇失质量率与硬度的下降及褐变度和丙二醛含量的上升,促使过氧化物酶和多酚氧化酶活性降低,减少总酚、维生素C及还原糖的损失。保藏至12d时,28.8、48.0、67.2mJ/cm^2处理组香菇总酚质量分数比对照组分别高28.44%、42.61%、17.37%,维生素C质量分数比对照组分别高68.56%、88.45%、63.42%,还原糖质量分数比对照组分别高12.87%、96.39%、54.16%,可见48.8mJ/cm^2处理组保持香菇营养品质的效果最佳。脉冲强光处理在控制食用菌品质方面具有潜在的应用前景。 展开更多
关键词 农产品 贮藏 品质控制 脉冲强光 香菇 保鲜品质
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壳聚糖涂膜鸡蛋贮藏中品质变化的动力学模型 预览
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作者 胡云峰 张利苹 +2 位作者 位锦锦 魏增宇 陈君然 《食品工业科技》 CAS 北大核心 2019年第1期87-91,共5页
为研究壳聚糖涂膜鸡蛋在贮藏过程中品质变化与贮藏时间的相关性,本文利用统计软件对5、10、15、20、35℃下贮藏的壳聚糖涂膜鸡蛋的气室直径、重量、蛋黄系数和哈夫单位随贮藏时间变化的数据进行拟合,建立动力学模型。结果表明,壳聚糖涂... 为研究壳聚糖涂膜鸡蛋在贮藏过程中品质变化与贮藏时间的相关性,本文利用统计软件对5、10、15、20、35℃下贮藏的壳聚糖涂膜鸡蛋的气室直径、重量、蛋黄系数和哈夫单位随贮藏时间变化的数据进行拟合,建立动力学模型。结果表明,壳聚糖涂膜鸡蛋的气室直径可以建立零级动力学模型,重量、蛋黄系数和哈夫单位可以建立一级动力学模型。且根据建立的模型,计算得到预测值与实测值拟合曲线的决定系数R^2分别为:0.9797(气室直径)、0.9601(重量)、0.9786(蛋黄系数)和0.991(哈夫单位),并且其平均相对误差w分别为1.95%、0.53%、7.66%和2.84%,均小于10%。说明本文建立的模型可分别预测壳聚糖涂膜鸡蛋的气室直径、重量、蛋黄系数和哈夫单位在5~35℃范围内的变化情况和壳聚糖涂膜鸡蛋的贮藏期,为壳聚糖涂膜鸡蛋的贮藏和销售提供参考。 展开更多
关键词 壳聚糖 鸡蛋 贮藏 品质变化 动力学模型
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苍溪猕猴桃贮藏品质研究 预览
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作者 蒋昭琼 程方平 +2 位作者 吝祥根 卢营蓬 易文裕 《湖北农业科学》 2019年第1期84-87,145共5页
以苍溪红心猕猴桃(Actinidia chinensis Planch)为试验材料,通过SPSS 19.0统计分析软件,采用独立样本t检验、单因素方差分析等统计分析方法对贮藏期间猕猴桃样品硬度、可溶性固形物含量、pH、可滴定酸含量、维生素C含量进行分析.结果表... 以苍溪红心猕猴桃(Actinidia chinensis Planch)为试验材料,通过SPSS 19.0统计分析软件,采用独立样本t检验、单因素方差分析等统计分析方法对贮藏期间猕猴桃样品硬度、可溶性固形物含量、pH、可滴定酸含量、维生素C含量进行分析.结果表明,随着贮藏时间的延长,猕猴桃样品的硬度下降,可溶性固形物含量增加,可滴定酸含量降低;维生素C含量亦逐渐降低,且贮藏前期降低较快,后期渐缓.贮藏温度对猕猴桃样品的硬度影响较大,与室温贮藏相比,低温冷藏的猕猴桃后熟变软速度较缓慢. 展开更多
关键词 猕猴桃(Actinidia CHINENSIS Planch) 贮藏 品质
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基于RGB颜色空间的冷冻猪肉储藏时间机器视觉判定 预览
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作者 李文采 李家鹏 +6 位作者 田寒友 邹昊 刘飞 白京 张振琪 王辉 王守伟 《农业工程学报》 EI CAS CSCD 北大核心 2019年第3期294-300,共7页
为解决冷冻猪肉储藏时间在人工判定中准确率和效率低的问题,该研究基于机器视觉和图像处理技术分析了冷冻猪肉表面图像RGB颜色特征,并将无光泽肌肉像素点比例作为自动判定冷冻猪肉储藏时间的特征参数。结果显示:将红度(R)与蓝度(B)的差... 为解决冷冻猪肉储藏时间在人工判定中准确率和效率低的问题,该研究基于机器视觉和图像处理技术分析了冷冻猪肉表面图像RGB颜色特征,并将无光泽肌肉像素点比例作为自动判定冷冻猪肉储藏时间的特征参数。结果显示:将红度(R)与蓝度(B)的差值小于等于30且红度(R)与绿度(G)的差值小于等于30作为第一特征条件,将红度(R)与蓝度(B)的差值小于等于30、红度(R)与绿度(G)的差值小于等于30且蓝度(B)大于等于100作为第二特征条件对冷冻猪肉颜色特征进行提取时,二值化图像能较好地识别冷冻猪肉表面总肌肉和无光泽肌肉。基于统计学分析,当储藏时间在3个月以内(1、2和3个月)和超过12个月(13、15和17个月)的冷冻猪肉无光泽肌肉像素点比例阈值为26.8%时,冷冻猪肉验证检测判定准确度最佳,分别为90.00%和81.67%。经图像分割后提出的基于无光泽肌肉像素点比例的判定方法可以为实际应用提供技术支持和参考。 展开更多
关键词 无损检测 图像处理 储藏 冷冻猪肉 无光泽肌肉像素点比例 机器视觉技术
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Generation of two-color polarization-adjustable radiation pulses for storage ring light source 预览
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作者 Wei-Hang Liu Yi Wu +2 位作者 Yi Jiao Zheng-He Bai Sheng Wang 《核技术:英文版》 SCIE CAS CSCD 2019年第4期123-131,共9页
To date, two-color pulses are widely used in pump–probe experiments. For a ring-based light source, the power of the spontaneous radiation fluctuates randomly in the longitudinal direction. It is difficult to produce... To date, two-color pulses are widely used in pump–probe experiments. For a ring-based light source, the power of the spontaneous radiation fluctuates randomly in the longitudinal direction. It is difficult to produce twocolor double pulses by optical methods. In this paper, we introduce a method based on the echo-enabled harmonic generation scheme that generates two-color pulses in a storage ring light source. By adopting crossed undulators and a phase shifter, the polarization of the two-color pulses can be easily switched. A numerical simulation based on a diffraction-limited storage ring, the Hefei Advanced Light Source, suggests that the time delay and spectral separation of the two pulses can be adjusted linearly by changing the pulse duration and chirp parameters of the seed laser. A circular polarization degree above 80% could be achieved. 展开更多
关键词 Two-color PULSES Echo-enabled harmonic GENERATION Diffraction-limited storage ring CROSSED UNDULATORS Circular polarization
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From sand to fast and stable silicon anode:Synthesis of hollow Si@void@C yolk-shell microspheres by aluminothermic reduction for lithium storage
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作者 Zhengwei Zhou Long Pan +2 位作者 Yitao Liu Xiaodong Zhu Xuming Xie 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第3期610-617,共8页
As an alloying type anode material, silicon is a promising alternative of graphitic carbon due to its high theoretical capacity and natural abundance. Developing an industrially viable silicon anode, however, is still... As an alloying type anode material, silicon is a promising alternative of graphitic carbon due to its high theoretical capacity and natural abundance. Developing an industrially viable silicon anode, however, is still a huge challenge because of several problems: First of all, the common process to synthesize a silicon anode is complicated, costly, and energy-intensive. Besides, the huge volume expansion, inevitable side reactions with the electrolyte, and low intrinsic conductivity of silicon are eventually responsible for the poor cyclability and unsatisfactory rate capability. Herein, we aim to address these issues by proposing synthesis of hollow Si@void@C yolk-shell microspheres from sand by low-temperature aluminothermic reduction, which energetically combines a cost-effective silicon source with an energy-efficient, highyield methodology. The hollow Si@void@C yolk-shell microspheres effectively accommodate the diffusion-induced stress by providing the hollow interior and the void space. Moreover, the carbon shell not only functions as an electrolyte-blocking layer to protect the silicon yolk from undesirable side reactions and SEI formation, but also acts as a conductive framework to reduce the resistance to electron and Li~+ ion transport. Benefiting from these synergistic effects, the hollow Si@void@C yolk-shell microspheres exhibit superior long-term cyclability and rate capability. 展开更多
关键词 Sand ANODE Lithium storage Aluminothermic reduction Si@void@C yolk-shell MICROSPHERES
水氮调控对设施土壤供氮潜力的影响
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作者 吴汉卿 李素捷 +7 位作者 刘洋屹 张鑫蕊 赵奇隆 李梦思 邹洪涛 党秀丽 张玉玲 虞娜 《生态学杂志》 CAS CSCD 北大核心 2019年第5期1410-1418,共9页
利用连续3年不同灌水下限(25、35和45 kPa)和施氮量(75、300和525 kg N·hm-2)的膜下滴灌设施番茄田间试验,探讨水氮调控对设施土壤供氮潜力的影响。结果表明:灌水下限和施氮量对土壤有机碳和全氮储量的影响显著,而水氮交互作用对... 利用连续3年不同灌水下限(25、35和45 kPa)和施氮量(75、300和525 kg N·hm-2)的膜下滴灌设施番茄田间试验,探讨水氮调控对设施土壤供氮潜力的影响。结果表明:灌水下限和施氮量对土壤有机碳和全氮储量的影响显著,而水氮交互作用对二者影响均不显著;灌水下限、施氮及其交互作用对休耕期0~30 cm设施土壤有机氮组分、微生物量氮和固定态铵储量的影响显著;不同水氮调控下,设施番茄休耕期0~30 cm土壤酸解氮组分储量及占酸解总氮比例的大小顺序依次为酸解氨基酸氮>酸解铵态氮>酸解未知氮>酸解氨基糖氮;酸解氨基酸氮是设施土壤中最主要的有机氮形态;酸解氨基酸氮与酸解铵态氮、酸解氨基糖氮、酸解总氮、非酸解氮、有机碳和全氮均呈显著相关;土壤固定态铵与酸解氨基酸氮呈显著正相关;土壤微生物量氮与酸解铵态氮、酸解氨基糖氮呈显著正相关,与酸解氨基酸氮呈显著负相关。土壤酸解氨基酸氮、土壤微生物量氮和固定态铵在一定程度上可作为设施土壤供氮潜力的反映指标,科学合理的水氮措施对提升设施土壤供氮潜力具有重要意义。 展开更多
关键词 水氮调控 设施土壤 供氮潜力 有机氮组分 微生物量氮 固定态铵 储量
Numerical simulation of enhancing coalbed methane recovery by injecting CO2 with heat injection
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作者 Hui-Huang Fang Shu-Xun Sang Shi-Qi Liu 《石油科学:英文版》 SCIE CAS CSCD 2019年第1期32-43,共12页
The technology used to enhance coalbed methane (CBM) recovery by injecting CO2 (CO2-ECBM) with heat, combining heat injection with CO2 injection, is still in its infancy;therefore, theoretical studies of this CO2-ECBM... The technology used to enhance coalbed methane (CBM) recovery by injecting CO2 (CO2-ECBM) with heat, combining heat injection with CO2 injection, is still in its infancy;therefore, theoretical studies of this CO2-ECBM technology should be perused. First, the coupling equations of the diffusion-adsorption-seepage-heat transfer fields of gas are established. The displacement processes under different pressures and temperatures are simulated by COMSOL. Finally, the displacement effects, a comparison of the CO2 storage capacity with the CH4 output and the effective influencing radius of CO2 injection are analyzed and discussed. The results show that (1) the displacement pressure and temperature are two key factors influencing the CH4 output and the CO2 storage capacity, and the increase in the CO2 storage capacity is more sensitive to temperature and pressure than the CH4 output.(2) The gas flow direction is from the injection hole to the discharge hole during the displacement process, and the regions with high velocity are concentrated at the injection hole and the discharge hole.(3) A reduction in the CH4 concentration and an increase in the CO2 concentration are obvious during the displacement process.(4) The effective influencing radius of injecting CO2 with heat increases with the increase in time and pressure. The relationship between the effective influencing radius and the injection time of CO2 has a power exponential function, and there is a linear relationship between the functional coefficient and the injection pressure of CO2. This numerical simulation study on enhancing CBM recovery by injecting CO2 with heat can further promote the implementation of CO2-ECBM project in deep coal seams. 展开更多
关键词 CO2-ECBM Numerical simulation DISPLACEMENT effect COMSOL CO2 storage capacity Effective influencing RADIUS
Liver graft preservation methods during cold ischemia phase and normothermic machine perfusion 预览
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作者 Konstantin Y Tchilikidi 《世界胃肠外科杂志:英文版(电子版)》 2019年第3期126-142,共17页
The growing demand for donor organs requires measures to expand donor pool. Those include extended criteria donors, such as elderly people, steatotic livers, donation after cardiac death, etc. Static cold storage to r... The growing demand for donor organs requires measures to expand donor pool. Those include extended criteria donors, such as elderly people, steatotic livers, donation after cardiac death, etc. Static cold storage to reduce metabolic requirements developed by Collins in late 1960s is the mainstay and the golden standard for donated organ protection. Hypothermic machine perfusion provides dynamic organ preservation at 4°C with protracted infusion of metabolic substrates to the graft during the ex vivo period. It has been used instead of static cold storage or after it as short perfusion in transplant center. Normothermic machine perfusion (NMP) delivers oxygen, and nutrition at physiological temperature mimicking regular environment in order to support cellular function. This would minimize effects of ischemia/reperfusion injury. Potentially, NMP may help to estimate graft functionality before implantation into a recipient. Clinical studies demonstrated at least its non-inferiority or better outcomes vs static cold storage. Regular grafts donated after brain death could be safely preserved with convenient static cold storage. Except for prolonged ischemia time where hypothermic machine perfusion started in transplant center could be estimated to provide possible positive reconditioning effect. Use of hypothermic machine perfusion in regular donation instead of static cold storage or in extended criteria donors requires further investigation. Multicenter randomized clinical trial supposed to be completed in December 2021. Extended criteria donors need additional measures for graft storage and assessment until its implantation. NMP is actively evaluating promising method for this purpose. Future studies are necessary for precise estimation and confirmation to issue clinical practice recommendations. 展开更多
关键词 Liver GRAFT PRESERVATION GRAFT PRESERVATION solutions Static cold storage Hypothermic MACHINE PERFUSION Normothermic MACHINE PERFUSION Ischemia-reperfusion injury Marginal GRAFTS DONATION after cardiac death Extended criteria donors Transpla complications
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Cloud Storage Security Assessment Through Equilibrium Analysis
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作者 Yuzhao Wu Yongqiang Lyu Yuanchun Shi 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第6期738-749,共12页
With ever greater amounts of data stored in cloud servers, data security and privacy issues have become increasingly important. Public cloud storage providers are semi-trustworthy because they may not have adequate se... With ever greater amounts of data stored in cloud servers, data security and privacy issues have become increasingly important. Public cloud storage providers are semi-trustworthy because they may not have adequate security mechanisms to protect user data from being stolen or misused. Therefore, it is crucial for cloud users to evaluate the security of cloud storage providers. However, existing security assessment methods mainly focus on external security risks without considering the trustworthiness of cloud providers. In addition, the widely used thirdparty mediators are assumed to be trusted and we are not aware of any work that considers the security of these mediators. This study fills these gaps by assessing the security of public cloud storage providers and third-party mediators through equilibrium analysis. More specifically, we conduct evaluations on a series of game models between public cloud storage providers and users to thoroughly analyze the security of different service scenarios.Using our proposed security assessment, users can determine the risk of whether their privacy data is likely to be hacked by the cloud service providers;the cloud service providers can also decide on strategies to make their services more trustworthy. An experimental study of 32 users verified our method and indicated its potential for real service improvement. 展开更多
关键词 CLOUD STORAGE SECURITY SECURITY ASSESSMENT EQUILIBRIUM analysis
基于电子鼻和气相色谱-质谱联用技术分析不同贮藏时间羊肉火腿香气成分 预览
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作者 王勇勤 郭新 +5 位作者 黄笠原 王远 王斌 张杰 张燕丽 王庆玲 《食品科学》 EI CAS CSCD 北大核心 2019年第2期215-221,共7页
采用电子鼻和顶空固相微萃取-气相色谱-质谱联用技术,对贮藏0、30、60、90、120、150d和180d的干腌羊肉火腿挥发性香气成分进行分析和检测。电子鼻测定结果表明不同贮藏时间羊肉火腿整体风味存在差异;气相色谱-质谱共鉴定出7类94种挥发... 采用电子鼻和顶空固相微萃取-气相色谱-质谱联用技术,对贮藏0、30、60、90、120、150d和180d的干腌羊肉火腿挥发性香气成分进行分析和检测。电子鼻测定结果表明不同贮藏时间羊肉火腿整体风味存在差异;气相色谱-质谱共鉴定出7类94种挥发性香气成分,烃类和醛类相对含量显著高于其他风味物质;偏最小二乘法表明3-甲硫基丁醛、戊醛、己醛、5-甲基己醛、壬醛、苯甲醛、2-甲基-2-十一烷硫醇、1-戊醇、1-辛烯-3-醇、2-辛酮、丁二酮、2-壬酮、乙酸、2,6-二甲基吡嗪等为羊肉火腿贮藏过程中特征风味物质。研究结果对了解羊肉火腿贮藏过程中风味构成及变化规律具有参考价值,有助于推进羊肉火腿的工业化进程。 展开更多
关键词 羊肉火腿 贮藏 电子鼻 气相色谱-质谱 香气
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NiPt nanoparticles supported on CeO2 nanospheres for efficient catalytic hydrogen generation from alkaline solution of hydrazine
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作者 Yana Men Jun Su +3 位作者 Xiangli Wang Ping Cai Gongzhen Cheng Wei Luo 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第3期634-637,共4页
Searching for highly efficient catalysts toward dehydrogenation of hydrazine for chemical hydrogen storage is highly desirable for the development of hydrogen economy. Herein, we report a simple in situ co-reduction s... Searching for highly efficient catalysts toward dehydrogenation of hydrazine for chemical hydrogen storage is highly desirable for the development of hydrogen economy. Herein, we report a simple in situ co-reduction synthesis of NiPt nanoparticles supported on CeO2 nanospheres and their superior catalytic performance for hydrogen generation from alkaline solution of hydrazine at room temperature. Thanks to the strong electronic interaction arising from synergistic effect at atomic lever and support-metal interaction between NiPt and CeO2.The obtained Ni5Pt5-CeO2 catalyst exhibits 100% hydrogen selectivity and superior catalytic performance for hydrogen generation from alkaline solution of hydrazine at room temperature, with a TOF value of 416 h 1. 展开更多
关键词 HYDROGEN storage HYDRAZINE HYDROGEN evolution CEO2 NANOSPHERES Support-metal in teraction
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