期刊文献+
共找到383篇文章
< 1 2 20 >
每页显示 20 50 100
Effects of Meat and Phosphate Level on Water-Holding Capacity and Texture of Emulsion-Type Sausage During Storage 被引量:24
1
作者 WANG Peng,XU Xing-lian and ZHOU Guang-hong Key Laboratory of Meat Processing and Quality Control,Ministry of Education/Nanjing Agricultural University,Nanjing 210095,P.R.China 《Agricultural Sciences in China》 CSCD 2009年第12期1475-1481,共7页
This paper was designed to verify the influence of phosphate on water-holding capacity (WHC) and texture of emulsiontype sausage prepared with pre-rigor meat, ageing meat or frozen meat. Pre-rigor pork, ageing pork ... This paper was designed to verify the influence of phosphate on water-holding capacity (WHC) and texture of emulsiontype sausage prepared with pre-rigor meat, ageing meat or frozen meat. Pre-rigor pork, ageing pork and frozen pork were pre-blended with five levels of phosphate and made into emulsion-type sausage. The yield, hardness and total expressible fluid (TEF) were measured with texture profile analysis machine and pressiometer when emulsion-type sausage was produced. Meanwhile, hardness and purge loss (PL) were measured during 30 d storage. As emusion-type sausage made by pre-rigor meat, higher yield and relatively stable hardness could be found. It indicated that increasing of phosphate level caused an alleviatable effects in increasing of hardness when emulsion-type sausage made by pre-rigor meat, but opposite effects made by ageing meat or frozen meat. The distribution of PL of emulsion-type sausage was found to be affected by phosphate addition. Significant decrease of PL could not be obtained by increasing of phosphate level during storage. Pre-rigor meat improved WHC and texture of emulsion-type sausage. Problem of WHC and texture of emulsiontype sausage during storage could not be resolved by single use of phosphate at relatively higher level (3%) of NaCl. 展开更多
关键词 MEAT emulsion-type sausage water-holding capacity TEXTURE
下载PDF
On the MIMO channel capacity saturation for spatially constrained receive region
2
作者 Wu Yujiang Nie Zaiping 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2007年第3期437-442,共6页
In MIMO wireless communication systems, when more and more antennas are packed into spatiallylimited receive region, the antenna saturation phenomenon will appear. Moreover, the electromagnetic interactions among ante... In MIMO wireless communication systems, when more and more antennas are packed into spatiallylimited receive region, the antenna saturation phenomenon will appear. Moreover, the electromagnetic interactions among antennas will also become stronger and stronger and affect the antenna saturation effect considerably. Despite this, few studies consider these two effects jointly. The effects of antenna saturation are investigated under the consideration of mutual coupling, thus a more practical and physically meaningful result can be obtained. 展开更多
关键词 MIMO systems capacity saturation mutual coupling spatially constrained array.
下载PDF
H-M Bearing Capacity of A Modified Suction Caisson Determined by Using Load-/Displacement-Controlled Methods 被引量:11
3
作者 张雨坤 高玉峰 +1 位作者 李大勇 Ali H.Mahfouz 《China Ocean Engineering》 SCIE EI CSCD 2016年第6期926-941,共16页
This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs (modified suction caissons) in the saturated marine fine sand. The lateral loads were appl... This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs (modified suction caissons) in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values. 展开更多
关键词 MSC (modified suction caisson) saturated marine fine sand model tests load- and displacement-controlled loading laterally combined bearing capacity earth pressure
下载PDF
The Scavenging of Free Radical and Oxygen Species Activities and Hydration Capacity of Collagen Hydrolysates from Walleye Pollock(Theragra chalcogramma) Skin 被引量:1
4
作者 ZHUANG Yongliang LI Bafang ZHAO Xue 《Journal of Ocean University of China》 SCIE CAS 2009年第2期171-176,共6页
Fish skin collagen hydrolysates (FSCH) were prepared from walleye pollock (Theragra chalcogramrna) using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3... Fish skin collagen hydrolysates (FSCH) were prepared from walleye pollock (Theragra chalcogramrna) using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3%. FSCH was mainly composed of low-molecular-weight peptides and the relative proportion of 〈1000Da fraction was 70.6%. Free radical and oxygen species scavenging activities of FSCH were investigated in four model systems, including diphenylpicrylhy-drazyl radical (DPPH), superoxide anion radical, hydroxyl radical and hydrogen peroxide model, and compared with that of a native antioxidant, reduced glutathione (GSH). FSCH was also evaluated by water-absorbing and water-holding capacity. The results showed that FSCH was able to scavenge free radical and oxygen species significantly and to enhance water-absorbing and water-holding capacity remarkably. Therefore FSCH may have potential applications in the medicine and food industries. 展开更多
关键词 walleye pollock COLLAGEN free radical-scavenging activity water-holding capacity
下载PDF
An Algorithm for Traffic Equilibrium Flow with Capacity Constraints of Arcs 被引量:1
5
作者 Zhi Lin 《Journal of Transportation Technologies》 2015年第4期240-246,共7页
In the traffic equilibrium problem, we introduce capacity constraints of arcs, extend Beckmann’s formula to include these constraints, and give an algorithm for traffic equilibrium flows with capacity constraints on ... In the traffic equilibrium problem, we introduce capacity constraints of arcs, extend Beckmann’s formula to include these constraints, and give an algorithm for traffic equilibrium flows with capacity constraints on arcs. Using an example, we illustrate the application of the algorithm and show that Beckmann’s formula is a sufficient condition only, not a necessary condition, for traffic equilibrium with capacity constraints of arcs. 展开更多
关键词 The Traffic EQUILIBRIUM Problem with capacity Constraints of ARCS EQUILIBRIUM FLOW ALGORITHM capacity of ARC saturated PATH
下载PDF
Study on Quantitative Model of Karst Drainage Basin Water-Holding Based on Principal Component Analysis: A Case Study of Guizhou, China
6
作者 Zhonghua He Xiaoxiang Chen +2 位作者 Hong Liang Fasu Huang Fang Zhao 《Advances in Remote Sensing》 2013年第3期205-213,共9页
In Karst drainage basins, there are the ground water and underground water exchanging frequently, and the shortage of water resources due to having the special double aquifer mediums and unique surface and subsurface ... In Karst drainage basins, there are the ground water and underground water exchanging frequently, and the shortage of water resources due to having the special double aquifer mediums and unique surface and subsurface river systematic structure. This paper is to select 20 research sampling areas coming fromGuizhouProvince, and according to the spectral characteristics of the catchment water-holding mediums and vegetations, and using the remote sensing technique, extract the watershed vegetation index. According to the principle of principal component analysis, using the software of Spss and Matlab is to analyze the impacts of watershed vegetation type on the catchment water-holding ability, and establish the principal component analysis function. Studies have shown that: 1) the watershed vegetation coverage rate plays an important role in Karst basin water-holding ability;2) the catchment water-holding ability is the comprehensive reflection and manifestation of the Catchment Water-storing Capacity (CWC);3) it is much better effects and higher accuracy to monitor/forecast the catchment water-holding volume by using the vegetation indices. 展开更多
关键词 KARST Drainage Basin Watershed Vegetation Index CATCHMENT water-holding Ability CATCHMENT Water-Storing capacity QUANTITATIVE Model
下载PDF
Study on Geometric Factors Influencing Saturation Flow Rate at Signalized Intersections under Heterogeneous Traffic Conditions 被引量:1
7
作者 B. G. Savitha R. Satya Murthy +2 位作者 H. S. Jagadeesh H. S. Sathish T. Sundararajan 《Journal of Transportation Technologies》 2017年第1期83-94,共12页
The main objective of intersection design is to facilitate the convenience, comfort, and safety of people traversing the intersection by enhancing the efficient movement of road users. The intersections on urban roads... The main objective of intersection design is to facilitate the convenience, comfort, and safety of people traversing the intersection by enhancing the efficient movement of road users. The intersections on urban roads in India generally cater to heterogeneous motorized traffic, along with slow-moving traffic including pedestrians. It is therefore necessary to consider saturation flow for mixed traffic conditions to evaluate the overall operation of signalized intersections. A proper traffic model must consider varying characteristics of all the road users to effectively design and efficiently manage signalized intersections. This paper presents the results of the study on analyses of saturation flow rate conducted at signalized intersections with mixed traffic conditions in the city of Bangalore, India. Studies were carried out at 15 signalized intersections in the city of Bangalore with varying geometric factors such as width of road (w), gradient of the road (g), and turning radius (r) for right turning vehicles. Saturation flow rate computed as per Highway Capacity manual (HCM: 2000), Indonesian highway capacity manual (IHCM), and IRC SP: 41-1994 was compared with the field observations. The geometric factors, which affect the saturation flow, have been considered in this study and accordingly a new model has been proposed for determining saturation flow. It has been shown that by the introduction of the suggested adjustment factors in this paper, the saturation flow rate can give better picture of the field conditions, especially under heterogeneous traffic conditions of an urban area. 展开更多
关键词 saturATION Flow capacity Signalized INTERSECTIONS HETEROGENEOUS TRAFFIC
下载PDF
Pulmonary rehabilitation outcome of exercise-induced oxygen desaturation in systemic sclerosis with interstitial lung disease
8
作者 Fujiko Someya Naoki Mugii 《Health》 2013年第6期1-5,共5页
While exercise capacity in systemic sclerosis with interstitial lung disease could be improved by exercise training, the training outcome of exercise-induced oxygen desaturation has not been examined. The aim of this ... While exercise capacity in systemic sclerosis with interstitial lung disease could be improved by exercise training, the training outcome of exercise-induced oxygen desaturation has not been examined. The aim of this study was to investigate the effect of pulmonary rehabilitation on exercise-induced oxygen desaturation during the six-minute walk test and to detect the factors affecting outcome retrospectively. Patients showing impaired exercise capacity (≤80% of predicted) and/or exercise-induced oxygen desaturation (≤-4% in SpO2) at the end of the six-minute walk test underwent routine walking exercise. Sixteen patients with stable systemic sclerosis completed exercise training for 55 days on average. The mean six-minute walk distance improved from 467 m to 502 m (P = 0.0012). The improvement in distance was negatively related to baseline distance (R2 = 0.28, P = 0.037), but was not related to parameters from pulmonary function tests and echocardiograms. Oxygen saturation was normal at rest, but was decreased in fifteen patients at the end of the test. Exercise-induced oxygen desaturation was positively related to the diffusion capacity of the lungs for carbon monoxide at baseline (R2 = 0.33, P = 0.026);however, it was not related to any cardiopulmonary parameters after intervention. Seven of sixteen patients ameliorated exercise-induced oxygen desaturation or showed no oxygen desaturation after exercise training, while others deteriorated. No cardiopulmonary parameters affected the training outcome of exercise-induced oxygen desaturation. Exercise train ing was beneficial in improving exercise tolerance, but training effects and mechanisms on exercise-induced oxygen desaturation still need more studies to be explained. 展开更多
关键词 SYSTEMIC SCLEROSIS INTERSTITIAL Lung Disease Training Oxygen saturATION EXERCISE capacity
下载PDF
Low-temperature combined with high-humidity thawing improves the water-holding capacity and biochemical properties of Portunus trituberculatus protein
9
作者 Jiangang Ling Xiaoting Xuan +4 位作者 Zihan Xu Tian Ding Xudong Lin Yan Cui Donghong Liu 《Food Quality and Safety》 SCIE CSCD 2021年第2期152-160,共9页
This study compared the effects of conventional thawing methods(water immersion thawing(WIT,(25±1)℃),natural air thawing(AT,(25±1)℃,relative humidity(RH(65±2)per cent),refrigerator thawing(RT,4℃,RH(8... This study compared the effects of conventional thawing methods(water immersion thawing(WIT,(25±1)℃),natural air thawing(AT,(25±1)℃,relative humidity(RH(65±2)per cent),refrigerator thawing(RT,4℃,RH(80±2)per cent)and low-temperature(LT)combined with high-humidity thawing LT,-1℃to 1℃(LT-1-1),2-4℃(LT2-4),5-7℃(LT5-7)and 8-10℃(LT8-10),RH>95 per cent)on the water-holding capacity,lipid oxidation and biochemical properties of Portunus trituberculatus(P.trituberculatus)myofibrillar protein.The results showed that WIT and AT significantly decreased the water-holding capacity while dramatically increasing lipid oxidation,protein oxidation and degeneration,resulting in serious P.trituberculatus quality deterioration.High humidity was beneficial for P.trituberculatus\.ha\A/\ng.The thawing time of P.trituberculatus under the conditions of LT2-4 was only 39.39 per cent of that of conventional air thawing at 4℃(RT),and the LT2-4 samples not only maintained better water-holding capacity but also had an obviously reduced degree of lipid oxidation,protein oxidation and denaturation.Thawed samples LT2-4 and LT5-7 provided better maintenance of P.trituberculatus quality than the LT-1-1 and LT8-10 samples.The best quality was exhibited after thawing at 2-4℃.The levels of thiobarbituric acid reacting substances,carbonyl content and surface hydrophobicity observably decreased in these samples,while the total sulfhydryl contents dramatically increased compared to those of conventionally thawed samples,indicating lower lipid oxidation and protein oxidation.Moreover,the Ca2+-ATPase activity of the sample thawed at 2-4℃(2.06 μmol Pi/mg prot/h)was markedly higher than that of samples subjected to WIT and AT.The product qualities observed after thawing at-1℃to 1℃,5-7℃and 8-10℃under LT were comparable to that observed by RT.Considering its thawing efficiency and product quality,LT is a suitable method for the thawing of P.trituberculatus,and the ideal thawing conditions were LT at 2-4℃. 展开更多
关键词 Portunus trituberculatus- thawing low temperature combined with high humidity water-holding capacity lipid oxidation biochemical properties of myofibrillar protein
原文传递
近红外光谱技术监控不同水平运动员递增负荷肌群肌氧变化特征
10
作者 毕学翠 郑晓鸿 张英平 《科学技术与工程》 北大核心 2024年第35期14947-14957,共11页
为了分析不同水平赛艇运动员在递增负荷测试中三个关键环节不同肌肉SMO_(2)变化特征,找出不同水平运动员SMO_(2)变化与常用指标变化的关系,提高递增负荷测试在赛艇训练监控中的针对性和实效性。通过实验将45名男子赛艇运动员,依据赛艇... 为了分析不同水平赛艇运动员在递增负荷测试中三个关键环节不同肌肉SMO_(2)变化特征,找出不同水平运动员SMO_(2)变化与常用指标变化的关系,提高递增负荷测试在赛艇训练监控中的针对性和实效性。通过实验将45名男子赛艇运动员,依据赛艇测功仪2000 m成绩分为A、B、C三个组。三组分别完成递增负荷测试,全程记录左右侧肱二头肌、竖脊肌和股内侧肌肌氧变化,同时记录心率、血乳酸等指标。实验数据使用Shapiro-Wilk法检验数据的正态性,相同运动员不同肌肉SMO_(2)变化测试结果对比使用非参数检验分析。不同水平运动员递增负荷测试结果的对比使用双尾独立T检验。相同运动员不同部位SMO_(2)与其他指标之间变化相关关系采用Pearson相关分析。结果表明:A、B、C三组不同部位ΔSMO_(2)在每级负荷中均与ΔHR有相关关系。A组股内侧肌ΔSMO_(2)与ΔHR全程高度相关(r=0.74-0.82,P<0.01),肱二头肌ΔSMO_(2)与ΔHR全程高度相关(r=0.32-0.88,P<0.01),竖脊肌ΔSMO_(2)与ΔHR全程高度相关(r=0.49-0.81,P<0.01);BLA变化幅度为-4.36 mmol/L时,对应B组ΔSMO_(2)变化幅度为-18.64%,C组ΔSMO_(2)变化幅度为-9.31%。可见不同水平运动员在赛艇递增负荷测试中均呈现出随着负荷增加SMO_(2)逐级下降的趋势。但是,不同水平运动员三个关键环节主要肌肉SMO_(2)变化特征呈现出一定程度的差异;赛艇递增负荷测试时,水平高的运动员综合ΔSMO_(2)变化率、ΔHR变化率和ΔBLA变化率相对较小;运动员SMO_(2)“拐点”与“乳酸阈拐点”相一致。相同BLA下,水平高的运动员SMO_(2)变化幅度较大,水平低的运动员SMO_(2)变化幅度较小。SMO_(2)变化只代表局部氧化代谢和运动能力,无法反应整体运动表现。 展开更多
关键词 近红外光谱技术 递增负荷测试 肌氧饱和度 有氧能力
下载PDF
CO_(2)-EOR过程中油藏储层构造封存能力的模拟
11
作者 王璐 刘森 +6 位作者 姬泽敏 廉黎明 田茂章 宋文枫 岳孝昆 房红旭 鲁效庆 《非常规油气》 2024年第2期99-107,共9页
为应对日益严峻的能源危机和温室效应,CO_(2)提高采收率技术脱颖而出,因此CO_(2)提高采收率后的地质封存安全性和相应的封存能力评估引起了广泛关注。借助数值模拟方法,基于吉林油田某区块油藏的实际储层条件,构建了注入CO_(2)含量为10%... 为应对日益严峻的能源危机和温室效应,CO_(2)提高采收率技术脱颖而出,因此CO_(2)提高采收率后的地质封存安全性和相应的封存能力评估引起了广泛关注。借助数值模拟方法,基于吉林油田某区块油藏的实际储层条件,构建了注入CO_(2)含量为10%~90%的9个模型,分别探究了含水饱和度为30%,50%和90%以及储层压力为10 MPa,20 MPa和30 MPa时油藏各相组分的分布规律;基于前人对封存CO_(2)安全储存状态划分的研究,最终明确了CO_(2)的安全封存量。结果表明:1)当含水饱和度(30%)和压力(10 MPa)一定时,增加CO_(2)含量(10%~90%)可大幅提高CO_(2)的有效封存体积分数(26%~93%);2)压力的提升(10~30 MPa)促进了CO_(2)在油相中的溶解,从而略微降低了储层的封存能力(18%~7%);3)含水饱和度对储层封存CO_(2)的能力的影响微乎其微。该研究旨在阐明不同条件下CO_(2)的构造埋存量,为相关研究提供借鉴。 展开更多
关键词 CO_(2)封存 封存能力评估 含水饱和度 储层压力 CO_(2)含量 数值模拟
下载PDF
鹰潭土壤重金属环境容量与承载力核算基础数据平台构建
12
作者 宋洁 于东升 +4 位作者 马利霞 王红梅 王鑫 张广星 王玉军 《农业环境科学学报》 CAS CSCD 北大核心 2024年第11期2595-2603,共9页
为提升地区土壤重金属污染评估与风险管控技术,针对铜采选和冶炼等工矿场地带来的土壤重金属污染物,研发鹰潭市土壤重金属环境容量与承载力核算基础数据平台系统。系统采用B/S架构,包括系统安全用户与主界面设置、数据管理与决策支持、... 为提升地区土壤重金属污染评估与风险管控技术,针对铜采选和冶炼等工矿场地带来的土壤重金属污染物,研发鹰潭市土壤重金属环境容量与承载力核算基础数据平台系统。系统采用B/S架构,包括系统安全用户与主界面设置、数据管理与决策支持、基础图层、环境质量评价、环境阈值、静态环境容量、动态环境容量、环境承载力和管理措施建议九大功能模块,新提出了基于环境阈值空间分异的区域土壤环境容量、饱和度以及承载力的概念和精细化算法。系统应用表明,该基础数据平台可为相关部门在区域土壤环境容量与承载力管理方面提供技术支撑。 展开更多
关键词 土壤重金属 环境阈值 环境容量与饱和度 环境承载力 可视化平台
下载PDF
黑土物理特性变化及改善途径
13
作者 张敏 韩晓增 +3 位作者 陆欣春 陈旭 严君 邹文秀 《土壤与作物》 2024年第2期173-180,共8页
东北黑土区位于世界四大黑土区之一,因其高肥力和有机质含量而闻名。作为我国主要的粮食生产基地之一,在保障国家粮食安全方面具有重要地位。然而,随着东北黑土地的开垦,养分的失调导致了黑土物理特性的变化和功能的退化,从而使得黑土... 东北黑土区位于世界四大黑土区之一,因其高肥力和有机质含量而闻名。作为我国主要的粮食生产基地之一,在保障国家粮食安全方面具有重要地位。然而,随着东北黑土地的开垦,养分的失调导致了黑土物理特性的变化和功能的退化,从而使得黑土肥力下降,威胁着该地区的粮食安全和生态安全。黑土物理特性发生变化,主要体现在黑土层土壤容重增加,孔隙度降低,水稳性团聚体减少,田间持水量下降等。采用合理的耕作方式和施肥制度能在不同程度上改善土壤物理特性,从而遏制土壤肥力的不断下降。本文总结了自黑土开垦以来土壤容重、水稳性团聚体、田间持水量和饱和导水率的变化,分析了耕作和有机物料等对土壤物理特性的重要调节作用,讨论了不同保护途径如何通过改善土壤物理特性达到提升土壤肥力的目的,最后从制定合理的耕作体系和有机培肥机制,优化作物种植模式等展望了未来黑土重点研究的方向。 展开更多
关键词 黑土 水稳性团聚体 容重 饱和导水率 田间持水量
下载PDF
考虑地形与理化性质的土壤关键水力特性多种模型构建与比较
14
作者 张赛亚 张珂 +3 位作者 晁丽君 李运平 张兆安 黄轶铭 《河海大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第3期42-50,共9页
为获取我国南方典型湿润山区关键土壤水力特性(饱和导水率(K_(s))与田间持水量(F_(c)))的精细空间数据,以南方典型湿润山区屯溪流域为样本采集区,以地形因子和土壤理化性质为输入,采用相关性分析方法建立了3种不同输入模式,采用多元线... 为获取我国南方典型湿润山区关键土壤水力特性(饱和导水率(K_(s))与田间持水量(F_(c)))的精细空间数据,以南方典型湿润山区屯溪流域为样本采集区,以地形因子和土壤理化性质为输入,采用相关性分析方法建立了3种不同输入模式,采用多元线性和机器学习技术构建了多元线性回归(MLR)、遗传算法-人工神经网络(GA-BP)、支持向量机回归(SVR)和随机森林(RF)4种表层土壤水力特性模型,并将4种模型同传统土壤转换函数(PTFs)进行了对比分析,探究了不同输入模式的优劣。结果表明:K_(s)估算效果由优到差排序为RF、SVR、MLR、GA-BP、PTFs,F_(c)估算效果由优到差排序为SVR、RF、GA-BP、MLR、PTFs;屯溪流域K_(s)和F_(c)的空间变化呈现一致性,整体空间分布与屯溪流域高程变化保持一致,说明湿润山区表层土壤水力特性与高程存在密切的非线性关系;SVR与RF模型更适用于小样本回归问题,GA-BP模型则需要较大的样本容量来充分捕捉特征以达到理想效果。 展开更多
关键词 土壤转换函数 多元线性回归 机器学习 饱和导水率 田间持水量
下载PDF
油藏型储气库库容影响因素及其变化规律研究
15
作者 丁洋洋 何勇明 +1 位作者 秦正山 刘文龙 《辽宁石油化工大学学报》 CAS 2024年第1期43-48,共6页
针对目前中、低含水饱和度对自由气库容量影响的研究较少的问题,开展室内实验模拟了多次注气-焖井-采气实验,并根据相似原理,利用实验数据建立了自由气库容量与初始含水饱和度、注采次数的量化表征模型。结果表明,自由气库容量随注采次... 针对目前中、低含水饱和度对自由气库容量影响的研究较少的问题,开展室内实验模拟了多次注气-焖井-采气实验,并根据相似原理,利用实验数据建立了自由气库容量与初始含水饱和度、注采次数的量化表征模型。结果表明,自由气库容量随注采次数的增多而增大,但单次注采后的增幅快速降低;含水饱和度(初始含水饱和大于50%)的提高有利于油藏改建储气库,但是建库初期的注采能力和库容提高相对缓慢;当初始含水饱和度由50%提高到85%时,经过6次注采后,含气饱和度降低幅度约9.27%,而当注采次数分别增至20、30、50时,自由气库容量增加幅度分别为0.51%、3.34%、6.61%。研究结果可为油藏型储气库的注采能力及库容评价提供借鉴。 展开更多
关键词 自由气库容量 注气-焖井-采气 含水饱和度 注采次数 容积法
下载PDF
页岩储层CO_(2)吸附解吸行为及弥散特征
16
作者 魏兵 陈海龙 +2 位作者 刘帅 赵金洲 Kadet Valeriy 《天然气工业》 EI CAS CSCD 北大核心 2024年第12期176-186,共11页
CO_(2)在页岩储层中的吸附/解吸行为是CO_(2)驱替页岩油气及CO_(2)地质封存的理论基础,研究驱替过程中的弥散特征对于评估二者混合程度、产出气纯度、采收率提高及CO_(2)封存效果具有重要意义。为此,以四川盆地下志留统龙马溪组和鄂尔... CO_(2)在页岩储层中的吸附/解吸行为是CO_(2)驱替页岩油气及CO_(2)地质封存的理论基础,研究驱替过程中的弥散特征对于评估二者混合程度、产出气纯度、采收率提高及CO_(2)封存效果具有重要意义。为此,以四川盆地下志留统龙马溪组和鄂尔多斯盆地上三叠统延长组页岩储层为研究对象,通过CO_(2)等温吸附和CO_(2)驱替CH4物理模拟实验,采用体积法和动态柱突破法,系统研究了不同页岩储层CO_(2)吸附量与温度、压力、页岩物性(有机碳含量、矿物组成、孔隙度和比表面积)的关系以及CO_(2)注入速度对弥散系数的影响规律。研究结果表明:①CO_(2)在页岩储层的吸附量随压力增加逐渐增大,当压力大于12 MPa后吸附量达到饱和状态,饱和吸附量为1.8~8.1 cm^(3)/g;②CO_(2)饱和吸附量与温度呈负相关关系,而与压力、页岩有机碳含量、比表面积和孔隙体积呈正相关关系;③CO_(2)驱替CH4的弥散过程处于对流与扩散共同主导的过渡区域,其表观弥散系数在10-7 m^(2)/s数量级且与CO_(2)注入速度呈线性相关关系。结论认为,研究成果揭示了CO_(2)弥散规律,初步证实了页岩储层注CO_(2)提高页岩油气采收率与碳封存的可行性,同时为开发方案优化设计提供了关键参数,为相关研究和工程实践奠定了理论基础。 展开更多
关键词 页岩气储层 注CO_(2)提高采收率 碳封存 吸附 解吸 CO_(2)驱替 饱和吸附量 页岩物性 弥散特征
下载PDF
Hydraulic characteristics and vegetation performance of the Yellow River sediment modified by biochar 被引量:1
17
作者 Baoyong Liu Mingji Liao +2 位作者 Yong Wan Xingxing He Dongli Wang 《Biogeotechnics》 2024年第2期1-11,共11页
The Yellow River sediment(YRS)is an important potential soil resource for the mine land reclamation and ecological restoration in the arid regions of northern China.However,it has the shortcomings of poor water-holdin... The Yellow River sediment(YRS)is an important potential soil resource for the mine land reclamation and ecological restoration in the arid regions of northern China.However,it has the shortcomings of poor water-holding capacity and needs to be modified urgently.Therefore,two types of biochar,namely rice husk biochar(RHB)and coconut shell biochar(CSB),were utilized in this study to modify the YRS and compared with rice husk ash(RHA).Some engineering properties of the modified YRS(MYRS),including pore structure,water retention,permeability,and vegetation performance,were investigated by considering the effects of biochar types and dosages.Results showed that the addition of the three materials decreased the bulk density of the YRS and increased the volume of extremely micro pore(d<0.3µm),as well as the effective porosity and capillary porosity,thus contributed to an increase in the water-holding capacity of the sediment.Among the three conditioners,RHB is optimal choice for improving the water-holding capacity of YRS.Furthermore,the effect becomes more pronounced with increasing application rates.With the addition of the three materials,the permeability coefficients of MYRS gradually decreased,while the water retention rate during evaporation significantly increased.The pot experiment showed that the three conditioners all had significant promoting effect on the growth of oats.In particular,compared to plain soil,the total biomass of oats grown for 21 days increased by 17.46%,32.14%,and 49.60%after adding 2%,4%,and 8%RHB,respectively.This study introduces a new approach for using YRS as planting soil in arid and semi-arid areas of China to facilitate mine ecological restoration. 展开更多
关键词 Biochar modification Yellow River sediment Soil water-holding capacity Permeability coefficient Vegetation performance
下载PDF
枯竭油藏型储气库库容量化室内实验研究
18
作者 丁洋洋 秦正山 +3 位作者 何勇明 刘文龙 向祖平 程泽华 《非常规油气》 2024年第4期89-96,共8页
在油藏改建地下储气库时,为了研究不同初始含水饱和度对库容的影响,利用实际矿场岩心开展了不同初始含水饱和度条件下气驱油水多轮次注采实验,分析了不同初始含水饱和度下气驱油水后的驱替效率及建库效果。结果表明,低含水饱和度条件下... 在油藏改建地下储气库时,为了研究不同初始含水饱和度对库容的影响,利用实际矿场岩心开展了不同初始含水饱和度条件下气驱油水多轮次注采实验,分析了不同初始含水饱和度下气驱油水后的驱替效率及建库效果。结果表明,低含水饱和度条件下,油相的相对渗透率显著高于水相而更易被驱替出,因此主要通过气驱油来提高储气空间;中、高含水饱和度时,水相更易被驱替出,储气空间的提高逐渐由被驱替出的原油体积贡献转向于由驱替出的水相体积贡献。相同注采轮次下,由于储层岩石水湿及渗吸作用,高初始含水饱和度时的剩余水饱和度增大,气驱油水总的驱替效率降低,储气库的注采能力和库容相对减小;储层初始含水饱和度增大会降低气驱油水的驱替效率,不利于提高原油采收率及储气库扩容;初始含水饱和度越高,储气库达容时间越久,建库初期的注采能力越低。该研究成果可为油藏型储气库注采能力评价和库容分析提供指导。 展开更多
关键词 枯竭油藏 储气库 含水饱和度 多轮次注采实验 驱替效率 储气空间
下载PDF
无烟煤超临界甲烷吸附模型的适用性研究
19
作者 王观宏 冯睿智 茹忠亮 《中国煤炭地质》 2024年第7期8-17,共10页
以赵庄煤矿无烟煤为研究对象,在4个不同温度下开展甲烷等温吸附实验,采用Langmuir、DR、DA模型对吸附数据进行拟合,并以标准偏差s为依据分析各模型的拟合效果。结果表明:对于Langmuir模型,直接拟合的效果优于间接拟合;对于DR、DA模型,... 以赵庄煤矿无烟煤为研究对象,在4个不同温度下开展甲烷等温吸附实验,采用Langmuir、DR、DA模型对吸附数据进行拟合,并以标准偏差s为依据分析各模型的拟合效果。结果表明:对于Langmuir模型,直接拟合的效果优于间接拟合;对于DR、DA模型,引入虚拟饱和蒸汽压的概念,并对比了5种虚拟饱和蒸汽压的计算方法,得出Amankwah法最为合适。从整体来看,基于微孔填充理论的DR、DA模型比基于单分子层吸附理论的Langmuir模型能更好地描述无烟煤中甲烷的吸附行为,其中DA-Amankwah法和DR-Amankwah法的拟合效果最好。Langmuir、DR和DA模型在各压力段的拟合程度表现出大致相同的规律:低压区拟合程度最高,拟合曲线与实测数据大致重合,中压区拟合吸附量小于实测吸附量;高压区拟合吸附量大于实测吸附量。虚拟饱和蒸汽压和温度是影响拟合饱和吸附量的重要因素,虚拟饱和蒸汽压值越高,拟合饱和吸附量越大,温度越高,拟合饱和吸附量越低。 展开更多
关键词 无烟煤 吸附模型 虚拟饱和蒸汽压 饱和吸附量 温度
下载PDF
内置式分数槽集中绕组伺服电机过载能力研究
20
作者 李文瑞 姜璐 +1 位作者 杨松 甘磊 《机电工程技术》 2024年第10期236-239,共4页
随着智能工业机器人的发展,伺服电机转矩密度及过载能力不断提升。然而过载提升将导致电机温升过高等问题。对此,提出一种具有高过载能力和较低温升的内置式伺服电机设计方案。首先,分析影响永磁同步电机过载能力的主要因素,并从基本转... 随着智能工业机器人的发展,伺服电机转矩密度及过载能力不断提升。然而过载提升将导致电机温升过高等问题。对此,提出一种具有高过载能力和较低温升的内置式伺服电机设计方案。首先,分析影响永磁同步电机过载能力的主要因素,并从基本转矩公式出发,研究电机空载反电势和交、直轴电感与极限输出转矩的内在关系;其次,对电机绕组形式及极槽配合等进行优选;再次,在定子冲片和铁心长度保持不变的条件下,利用有限元法对比分析不同内置式转子拓扑结构和电、磁负荷配比对过载能力的影响规律。仿真结果表明,内置式“一”字型、“V”字型和Spoke型拓扑聚磁性逐渐增强,抗饱和能力逐渐减弱,最大转矩分别为6.1、5.8、5.7 N·m。另外通过优化电、磁负荷配比,可以有效抑制磁路饱和,提高过载能力。 展开更多
关键词 过载能力 磁路饱和 内置式伺服电机
下载PDF
上一页 1 2 20 下一页 到第
使用帮助 返回顶部