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Methodology Validation of Microbial Limit Test of Bupi Qiangli Ointment
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作者 李江萍 杨亮 蒋玲 《Agricultural Science & Technology》 CAS 2017年第2期365-367,共3页
[Objective] This study was conducted to establish a microbial limit test method for Bupi Qiangli Ointment. [Method] The conventional method and medium dilution method were used for bacterial, mold and yeast counting i... [Objective] This study was conducted to establish a microbial limit test method for Bupi Qiangli Ointment. [Method] The conventional method and medium dilution method were used for bacterial, mold and yeast counting in sample recovery test. [Result] The medium dilution method (1:10 test solution, 0.5 ml/plate) could effectively eliminate the inhibition effect of the Bupi Qiangli Ointment, and the recovery of Staphylococcus aureus was greater than 70% in the 3 batches of samples; and the conventional method exhibited the recoveries of E. coil, Bacillus subtilis, Candida albicans and Aspergillus greater than 70% in the 3 batches of samples. [Conclusion] Due to Bupi Qiangli Ointment has strongly antibacterial effect on Staphylococcus au- reus, the medium dilution method was used for bacterial counting, and the conventional method was used for mold and yeast counting; and the conventional method was used for controlled bacterium examination of E. coll. 展开更多
关键词 Bupi Qiangli Ointment Microbial limit tests Method validation Medium dilution method
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Establishment of Microbial Limit Test Methods for Two Hospital Preparations
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作者 Renhui YANG Yongmin CHEN +3 位作者 Yufen XIA Yongyue GAO Yuling LUO Xianmei XU 《Agricultural Biotechnology》 CAS 2023年第3期92-94,127,共4页
[Objectives] This study was conducted to establish microbial limit test methods for traditional Chinese medicine preparations Yunpi Granules and Bupi Qiangli Paste. [Methods] According to General Rules of Part IV of C... [Objectives] This study was conducted to establish microbial limit test methods for traditional Chinese medicine preparations Yunpi Granules and Bupi Qiangli Paste. [Methods] According to General Rules of Part IV of Chinese Pharmacopoeia, applicability tests were conducted on microbial limit test methods for the above two traditional Chinese medicine preparations by the plate method. [Results] The established methods showed recovery values in the range of 0.5-2.0 for both experimental strains, and the control bacteria could be detected in the experimental group, but not in the negative control group. [Conclusions] The microbial limit test methods were reliable for the two traditional Chinese medicine preparations and could be used for quality control. 展开更多
关键词 Yunpi Granules Bupi Qiangli Paste Microbial limit test Method applicability test
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Applicability of Microbial Limit Test Method for Qingyan Zhisou Powder
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作者 Changping TAI Yuanfeng YANG +3 位作者 Yongmin CHEN Yuling LUO Keqin MA Renhui YANG 《Agricultural Biotechnology》 CAS 2023年第2期117-120,共4页
[Objectives]This study was conducted to establish a microbial limit test method for Qingyan Zhisou Powder.[Methods]Applicability tests were carried out according to Microbial Limit Tests of Non-sterile Products,Genera... [Objectives]This study was conducted to establish a microbial limit test method for Qingyan Zhisou Powder.[Methods]Applicability tests were carried out according to Microbial Limit Tests of Non-sterile Products,General Rules 1105-1107 of Part IV of Chinese Pharmacopoeia,2020.[Results]Qingyan Zhisou Powder had a strong bacteriostatic effect on Pseudomonas aeruginosa.After increasing the dilution ratio(1:40),the bacteriostatic effect was obviously eliminated.When the total number of aerobic microbes was determined by the test liquid dilution method(1:40),the recovery values were in the range of 50%-200%;and when using the test liquid(1:10)to determine the total number of mold and yeasts,the recovery ranged from 50%to 200%.Escherichia coli,Salmonella and bile-tolerant Gram-negative bacteria were detected by both the routine method and dilution method in experimental groups.[Conclusions]The microbial limit test of Qingyan Zhisou Powder adopted the test liquid dilution method,and the routine method could be used for the test of Escherichia coli,Salmonella and bile-tolerant Gram-negative bacteria.The applicability test of the method is feasible,with scientific and accurate results,and the method can effectively control the quality of the preparation and is recommended for popularization. 展开更多
关键词 Qingyan Zhisou Powder Microbial limit test Method applicability
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Validation of Microbial Limit Test Methods of Tongmai Tangyanming Capsule
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作者 Renhui YANG Yali YAO Xunrong ZHOU 《Agricultural Biotechnology》 CAS 2018年第1期104-108,共5页
[ Objectives] This study was conducted to establish a method for microbial limit test of Tongmai Tangyanming Capsule. [ Methods] According to the Chinese Pharmacopoei 2015 edition of the four general rules, the microb... [ Objectives] This study was conducted to establish a method for microbial limit test of Tongmai Tangyanming Capsule. [ Methods] According to the Chinese Pharmacopoei 2015 edition of the four general rules, the microbiological limits of non-sterile products were verified. [ Results] Tongmai Tangyanming Capsule has a strong inhibitory effect on Bacillus subtilis and Candida albicans. The antimicrobial activity was significantly eliminated after increasing the diluent ( 1 : 20) ; and the recoveries were in the range of 0.5 -2 when the total quantities of aerobic microbes were determined by dilution method (1:20). When the total quantities of mould and yeast were determined by dilution method (1:20), the recoveries were from 0.5 to 2, and Escherichia coli, cholate-tolerant Gram-negative bacteria and Salmonella can be detected by the test solution dilution method. [ Condusions] With the plate method, the total quantities of aerobic bacteria and the quantities of mould and yeast were examined by increasing diluent, and conventional method was used for examination of control bacteria including E. coli, cholatetolerant Gram-negative bacteria and Salmonella. This method has been proved effective for microbial limit test of Tongmai Tangyanming Capsule, and can effectively control the quality of the preparation. The method is accurate and reliable. 展开更多
关键词 Tongmai Tangyanming Capsule Microbial limit test method Dilution method
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Validation of Microbial Limit Test Methods of Compound Gangbangui Capsule
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作者 Xiangling QU Xianmei XU +1 位作者 Sibu MA Renhui YANG 《Agricultural Biotechnology》 CAS 2018年第2期105-108,共4页
[Objectives] This study was conducted to establish a method for microbial limit test of Compound Gangbangui Capsule. [Methods] According to the Chinese Pharmacopoei 2015 edition of the four general rules,the microbiol... [Objectives] This study was conducted to establish a method for microbial limit test of Compound Gangbangui Capsule. [Methods] According to the Chinese Pharmacopoei 2015 edition of the four general rules,the microbiological limits of non-sterile products were verified. [Results]Compound Gangbangui Capsule has a strong inhibitory effect on S. aureus,and the antimicrobial activity was significantly eliminated after increasing the diluent( 1∶ 20); and the recoveries were in the range of 0. 5-2. 0 when the total quantities of aerobic microbes were determined by dilution method( 1∶ 20). When the total quantities of mould and yeast were determined by conventional method( 1∶ 20),the recoveries were from 0. 5 to 2. 0,and Escherichia coli can be detected in experimental groups by the test solution dilution method. [Conclusions]With the plate method,the total quantities of aerobic bacteria and the quantities of mould and yeast were examined by increasing diluent and conventional method,respectively,and control bacteria,E. coli was examined by conventional method. This method has been proved effective for microbial limit test of Compound Gangbangui Capsule,and can effectively control the quality of the preparation. The method is accurate and reliable. 展开更多
关键词 Compound Gangbangui Capsule Microbial limit test method Dilution methodHome
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Validation for Microbial Limit Test Method of Compound Yu E Nose Drops
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作者 Renhui YANG Peixue CAO +1 位作者 Zhen ZENG Xiangling QU 《Agricultural Biotechnology》 CAS 2019年第5期125-128,共4页
[Objectives] This study was conducted to establish a method for microbial limit test of Compound Yu E Nose Drops.[Methods] According to the Chinese Pharmacopoei (General Rules in the fourth part of the 2015 edition),t... [Objectives] This study was conducted to establish a method for microbial limit test of Compound Yu E Nose Drops.[Methods] According to the Chinese Pharmacopoei (General Rules in the fourth part of the 2015 edition),the microbial limit test method for Compound Yu E Nose Drops was verified.[Results] Compound Yu E Nose Drops has a strong inhibitory effect on Staphylococcus aureus and Bacillus subtilis,and the inhibitory activity was significantly eliminated after increasing the diluent (1∶ 20).The recoveries were all in the range of 0.5-2.0 when the total quantities of aerobic microbes were determined by the dilution method (1∶ 20).When the total quantities of mould and yeast were determined by the conventional method,the recoveries were both in the range of 0.5-2.0.When examining control bacteria,Escherichia coli,S.aureus and Pseudomonas aeruginosa can all be detected in the test groups by the test liquid dilution method.[Conclusions] For Compound Yu E Nose Drops,the total quantities of aerobic microbe can be counted by the dilution method;the quantities of mould and yeast can be examined by the conventional plate method;and the conventional method can be used for control microbe examination. 展开更多
关键词 COMPOUND Yu E NOSE DROPS MICROBIAL limit test DILUTION method
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Prediction of plane-strain specimen geometry to efficiently obtain a forming limit diagram by Marciniak test 被引量:1
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作者 Qing-bao Yang Jun-ying Min +4 位作者 John E. Carsley Yuan-yuan Wen Bernd Kuhlenkotter Thomas B. Stoughton Jian-ping Lin 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2018年第5期539-545,共7页
Plane-strain forming limit strain (also known as FLD0) is an important data point on a forming limit diagram (FLD). The effects of friction coefficients and material parameters on the specimen width associated wit... Plane-strain forming limit strain (also known as FLD0) is an important data point on a forming limit diagram (FLD). The effects of friction coefficients and material parameters on the specimen width associated with the FLDo (W FLD0) in Marciniak test were studied by finite element simulation. WFLD0 was expressed as a function of the Lankford coefficients, n-value, k-value and sheet thickness and validated with various sheet materials. The determination of W FLD0 is of significance not only to reduce iterative attempts to accurately obtain FLDo, but also to obtain a full valid FLD with the least number of test specimens, which largely increases the efficiency and reduces cost to experimentally measure valid FLDs. 展开更多
关键词 Forming limit test ·Sheet metal· Plane-strain state· Marciniak test
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我国宠物饲料安全风险及监管中亟待解决的问题 被引量:1
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作者 孙国荣 陈磊 +1 位作者 金琦琦 周静 《中国饲料》 北大核心 2025年第1期153-156,共4页
近年来,我国宠物饲料行业发展的规模和速度惊人,市场份额不断增大,同时也显露出不少问题。本文侧重于宠物饲料质量安全,从宠物营养要求特点出发,对存在的有害微生物、霉菌毒素、药物及添加剂、有毒有害元素等风险因素进行分析总结,同时... 近年来,我国宠物饲料行业发展的规模和速度惊人,市场份额不断增大,同时也显露出不少问题。本文侧重于宠物饲料质量安全,从宠物营养要求特点出发,对存在的有害微生物、霉菌毒素、药物及添加剂、有毒有害元素等风险因素进行分析总结,同时提出质量安全监管中限量标准、检测方法和监管体系中存在的亟待解决的问题,希望对生产加工、科研开发、监管工作提供参考。 展开更多
关键词 宠物饲料 质量安全 风险因素 限量标准 检测方法 风险监管
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Forming Limit Stress Diagram Prediction of Aluminum Alloy 5052 Based on GTN Model Parameters Determined by In Situ Tensile Test 被引量:21
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作者 HE Min LI Fuguo WANG Zhigang 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2011年第3期378-386,共9页
The conventional forming limit diagram (FLD) is described as a plot of major strain versus minor strain. However, FLD is dependent on forming history and strain path. In the present study, a forming limit stress-bas... The conventional forming limit diagram (FLD) is described as a plot of major strain versus minor strain. However, FLD is dependent on forming history and strain path. In the present study, a forming limit stress-based diagram (FLSD) has been adopted to predict the fracture limit of aluminum alloy (AA) 5052-O1 sheet. Nakazima test is simulated by plastic constitutive formula derived from the modified Gurson-Tvergaard-Needleman (GTN) model. An in situ tensile test with scanning electron microscope (SEM) is proposed to determine the parameters in GTN model. The damage evolution is observed and recorded, and the parameters of GTN model are identified through counting void fraction at three damage stages of AA5052-O 1. According to the experimental results, the original void volume fraction, the volume fraction of potential nucleated voids, the critical void volume fraction, the void volume fraction at the final failure of material are assigned as 0.002 918, 0.024 9, 0.030 103, 0.048 54, respectively. The stress and strain are obtained at the last loading step before crack. FLSD and FLD of AA5052-O 1 are plotted. Compared with the experimental Nakazima test and uniaxial tensile test, the predicted results show a good agreement. The parameters determined by in situ tensile test can be applied to the research of the forming limit for ductile metals. 展开更多
关键词 forming limit stress diagram GTN model in situ tensile test void damage aluminum alloy 5052-O1 sheet metal forming
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自动驾驶极限道路线形测试场景生成方法
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作者 南春丽 阎子涵 +3 位作者 杨澜 赵祥模 宁航 靳明辉 《中国公路学报》 北大核心 2025年第8期388-396,共9页
极限道路线形是影响交通安全的主要因素之一,同时极限场景测试也是自动驾驶测试面临的主要挑战。针对目前自动驾驶测试较少考虑极限道路线形的问题,从道路线形设计的角度,提出一种极限道路线形测试场景生成方法。使用基于设计理论方法... 极限道路线形是影响交通安全的主要因素之一,同时极限场景测试也是自动驾驶测试面临的主要挑战。针对目前自动驾驶测试较少考虑极限道路线形的问题,从道路线形设计的角度,提出一种极限道路线形测试场景生成方法。使用基于设计理论方法和融合模型-数据驱动方法,提出了未建道路条件下的线形自动生成方法和既有道路条件下的生长因子算法,构建自动驾驶极限道路线形测试场景。未建道路条件下,依据规范和标准,将线形场景分为5种,通过改变元素极限参数、缩放、旋转等几何变换扩充基于设计的线形场景样本量;既有道路条件下,从高精度遥感影像中提取典型真实道路线形组成及几何特征参数。针对缓和曲线线形元素难以识别的问题,建立了分段数学模型,将整个道路线形分割为基本线形组成元素;设计了LSTM-GRU网络,识别基本线形组成元素类型,给出了生长因子算法,计算各基本线形组成元素几何特征参数。使用PreScan仿真平台和自动驾驶封闭测试场地,进行仿真测试和实车测试。结果表明:生成的极限道路线形场景安全系数均接近极限值1,变异系数均接近极限值10%;在标准规定的范围内,可以作为极限道路线形测试场景。 展开更多
关键词 交通工程 道路线形 自动驾驶测试 极限场景生成 模型驱动 数据驱动
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壮药尖锐湿疣外洗剂微生物限度检查方法研究
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作者 陈壮 杨雪 +2 位作者 苏善美 韦金彩 林忆龙 《中国民族民间医药》 2025年第2期27-30,64,共5页
目的:建立壮药尖锐湿疣外洗剂微生物限度检查方法。方法:依据2020版《中国药典》,采用平皿法考察需氧菌、霉菌和酵母菌总数,并对控制菌检查系统适用性进行考察。结果:壮药尖锐湿疣外洗剂对枯草芽孢杆菌和铜绿假单胞菌存在一定的抑制作用... 目的:建立壮药尖锐湿疣外洗剂微生物限度检查方法。方法:依据2020版《中国药典》,采用平皿法考察需氧菌、霉菌和酵母菌总数,并对控制菌检查系统适用性进行考察。结果:壮药尖锐湿疣外洗剂对枯草芽孢杆菌和铜绿假单胞菌存在一定的抑制作用,通过稀释样品可有效地消除抑菌作用。消除抑菌性后,需氧菌、霉菌和酵母菌总数方法适应性检查中,菌液回收率在0.7~1.3之间,符合规定。控制菌检查中,壮药尖锐湿疣外洗剂试验组能检出金黄色葡萄球菌和铜绿假单胞菌的反应特性,符合要求。结论:建立的微生物限度检查方法稳定可靠,适用于壮药尖锐湿疣外洗剂微生物限度检查。 展开更多
关键词 壮药尖锐湿疣外洗剂 微生物限度检查 抑菌作用
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Cautionary Remarks When Testing Agreement between Two Raters for Continuous Scale Measurements: A Tutorial in Clinical Epidemiology with Implementation Using R
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作者 Mohamed M. Shoukri 《Open Journal of Epidemiology》 2024年第1期56-74,共19页
Background: When continuous scale measurements are available, agreements between two measuring devices are assessed both graphically and analytically. In clinical investigations, Bland and Altman proposed plotting sub... Background: When continuous scale measurements are available, agreements between two measuring devices are assessed both graphically and analytically. In clinical investigations, Bland and Altman proposed plotting subject-wise differences between raters against subject-wise averages. In order to scientifically assess agreement, Bartko recommended combining the graphical approach with the statistical analytic procedure suggested by Bradley and Blackwood. The advantage of using this approach is that it enables significance testing and sample size estimation. We noted that the direct use of the results of the regression is misleading and we provide a correction in this regard. Methods: Graphical and linear models are used to assess agreements for continuous scale measurements. We demonstrate that software linear regression results should not be readily used and we provided correct analytic procedures. The degrees of freedom of the F-statistics are incorrectly reported, and we propose methods to overcome this problem by introducing the correct analytic form of the F statistic. Methods for sample size estimation using R-functions are also given. Results: We believe that the tutorial and the R-codes are useful tools for testing and estimating agreement between two rating protocols for continuous scale measurements. The interested reader may use the codes and apply them to their available data when the issue of agreement between two raters is the subject of interest. 展开更多
关键词 limits of Agreement Pitman and Morgan tests test of Parallelism The Arcsine Variance Stabilizing Transformation Sample Size Estimation
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2种医院制剂微生物限度检查方法验证 被引量:1
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作者 杨晓峰 李惠英 +2 位作者 李聃 刘晓宁 秦利芬 《云南化工》 2025年第2期85-89,共5页
目的:建立2种医院制剂(新止咳合剂、小儿颠茄溴化钠口服溶液)的微生物限度检查方法。方法:按照2020年版《中国药典》(通则9202),采用平皿法开展微生物计数方法适用性试验;用常规法对控制菌进行检查。需氧菌、霉菌和酵母菌总数计数计算... 目的:建立2种医院制剂(新止咳合剂、小儿颠茄溴化钠口服溶液)的微生物限度检查方法。方法:按照2020年版《中国药典》(通则9202),采用平皿法开展微生物计数方法适用性试验;用常规法对控制菌进行检查。需氧菌、霉菌和酵母菌总数计数计算回收率。结果:需氧菌、霉菌和酵母菌总数验证中各试验菌的回收率均在0.5~2之间,按常规法可以检出控制菌。结论:通过方法适用性验证,平皿法操作简单,能真实反映2种制剂微生物检测结果。 展开更多
关键词 医院制剂 微生物限度检查 平皿法 方法适用性试验 回收率 口服制剂
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悬索桥索梁销接节点抗火性能研究
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作者 李雪红 华晓烨 +2 位作者 杨国明 李亮 吴豪放 《桥梁建设》 北大核心 2025年第2期100-107,共8页
为了解悬索桥索梁销接节点在火灾下的响应特性和破坏形态,对该类节点开展了持载火灾试验和有限元研究。以南京新生圩长江大桥为背景,设计、制作索梁销接节点模型,采用拉压试验机张拉吊索至成桥索力后,采用电阻炉模拟火灾升温,分析持载... 为了解悬索桥索梁销接节点在火灾下的响应特性和破坏形态,对该类节点开展了持载火灾试验和有限元研究。以南京新生圩长江大桥为背景,设计、制作索梁销接节点模型,采用拉压试验机张拉吊索至成桥索力后,采用电阻炉模拟火灾升温,分析持载过程中节点应力、应变、温度、破坏形态等,并采用有限元法研究其应力及温度分布规律。结果表明:持载火灾试验中,节点模型在103 min时发生塑性变形,临界温度为864℃;134 min时叉耳发生颈缩拉断破坏,表面温度为1015℃。有限元模拟中,节点破坏时,叉耳的最大应力位于销孔两侧,吊耳受应力重分布影响,最大应力由销孔两侧逐渐转移到腹板底部,销轴两端应力较小、中间应力较大。对比有限元与试验结果,碳氢(HC)升温曲线和ISO834标准升温曲线作用下节点响应及抗火性能的变化规律基本一致,HC升温曲线作用下的节点破坏时间约30 min。 展开更多
关键词 悬索桥 索梁销接节点 抗火性能 破坏形态 耐火极限 持载火灾试验 有限元法
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GC法测定氯化乙酰甲胆碱中的乙醛和环氧丙烷
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作者 彭丽娇 李文明 +1 位作者 赵春杰 赵旻 《华西药学杂志》 北大核心 2025年第2期178-180,共3页
目的采用GC法检测氯化乙酰甲胆碱中基因毒性杂质乙醛和环氧丙烷的限量。方法采用DB-WAX色谱柱(30 m×320μm,0.5μm),检测器温度250℃,进样口温度150℃,柱流速1.5 mL·min^(-1);采用程序升温,起始温度为40℃,维持3 min,以15℃&#... 目的采用GC法检测氯化乙酰甲胆碱中基因毒性杂质乙醛和环氧丙烷的限量。方法采用DB-WAX色谱柱(30 m×320μm,0.5μm),检测器温度250℃,进样口温度150℃,柱流速1.5 mL·min^(-1);采用程序升温,起始温度为40℃,维持3 min,以15℃·min^(-1)升至50℃,再以30℃·min^(-1)升至240℃,维持3 min;以顶空瓶平衡温度85℃,平衡15 min作为顶空条件。结果乙醛和环氧丙烷分离良好;乙醛的检测限为0.08μg·mL^(-1),加样回收率为90.27%~102.40%,在0.27~3.0μg·mL^(-1)与峰面积的线性关系良好(r=0.9992);环氧丙烷的检测限为0.10μg·mL^(-1),加样回收率为79.25%~87.91%,在0.33~3.00μg·mL^(-1)与峰面积的线性关系良好(r=0.9992)。结论所用方法操作简单,准确度高,可用于氯化乙酰甲胆碱原料中乙醛和环氧丙烷的检测。 展开更多
关键词 氯化乙酰甲胆碱 乙醛 环氧丙烷 气相色谱 顶空 基因毒性 限量检查
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氟雷拉纳咀嚼片微生物限度检查方法的适用性试验
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作者 白玉婷 张欣欣 +4 位作者 于方凌 白玉彬 李海權 张继瑜 李冰 《中国兽医杂志》 北大核心 2025年第4期80-86,共7页
为了建立并验证氟雷拉纳咀嚼片微生物限度检查方法,本试验分别考察平皿常规法和平皿中和法去除氟雷拉纳咀嚼片中抑菌成分活性的效果,进行需氧菌(枯草芽孢杆菌、金黄色葡萄球菌、铜绿假单胞菌)、霉菌和酵母菌总数的测定,并对控制菌(大肠... 为了建立并验证氟雷拉纳咀嚼片微生物限度检查方法,本试验分别考察平皿常规法和平皿中和法去除氟雷拉纳咀嚼片中抑菌成分活性的效果,进行需氧菌(枯草芽孢杆菌、金黄色葡萄球菌、铜绿假单胞菌)、霉菌和酵母菌总数的测定,并对控制菌(大肠埃希菌和沙门菌)进行检查,筛选出最优的检查方法进行供试品微生物限度检查。结果显示,中和法可以较好地消除氟雷拉纳咀嚼片中抑菌成分的抑菌活性,使用中和法进行试验,需氧菌、霉菌和酵母菌的回收率均介于50%~200%,控制菌阳性对照组中菌落生长良好,供试品组和阴性对照组中均无细菌生长,符合《中华人民共和国兽药典》规定,可使用中和法进行供试品中微生物计数及控制菌大肠埃希菌和沙门菌检查。本试验所建立方法(中和法)准确可行,能有效去除氟雷拉纳咀嚼片处方中抑菌成分的抑菌性,适用于氟雷拉纳咀嚼片微生物限度检查,为氟雷拉纳咀嚼片的质量评价提供参考。 展开更多
关键词 氟雷拉纳咀嚼片 微生物限度检查 适用性试验 中和法
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某型高速精密电主轴角接触球轴承的失效分析 被引量:1
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作者 刘艳 崔永存 +2 位作者 方俊 王登科 李伟旺 《机电工程》 北大核心 2025年第1期82-89,共8页
针对某型高速精密电主轴用7003陶瓷球轴承在极限转速试验中出现异常振动和噪音等问题,从端口位置、形态、显微组织、相组成等方面对轴承失效原因进行了分析研究。首先,采用了洛氏硬度检测的方法对失效轴承的内、外滚道进行了检测,研究... 针对某型高速精密电主轴用7003陶瓷球轴承在极限转速试验中出现异常振动和噪音等问题,从端口位置、形态、显微组织、相组成等方面对轴承失效原因进行了分析研究。首先,采用了洛氏硬度检测的方法对失效轴承的内、外滚道进行了检测,研究了失效轴承内、外滚道的洛氏硬度;然后,采用了金相组织分析的方式,对轴承内、外滚道失效部位进行了分析,研究了轴承内、外滚道失效部位的金相组织成分;最后,采用了扫描电子显微镜(SEM),对轴承内、外滚道,内、外滚道断口以及滚动体失效部位进行了检测与分析,研究了轴承失效部位的表面组织显微形貌及能谱仪(EDS),进而对轴承失效进行了详细分析。研究结果表明:轴承内圈产生失效剥落的主要原因为内圈滚道表面的碳化物、氧化物在应力接触面堆积,从而加剧了其表面的氧化程度。由于内圈制造工艺缺陷将导致轴承发生早期失效,建议产品加工过程中严格执行热处理工艺,避免产生不合格组织。 展开更多
关键词 陶瓷球轴承 金相组织 扫描电子显微镜 能谱仪 极限转速试验 失效分析
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钢筋混凝土单层平面框架火灾行为的尺寸效应
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作者 张海燕 李广洲 +1 位作者 李绮玉 吴波 《湖南大学学报(自然科学版)》 北大核心 2025年第3期15-28,共14页
为探究钢筋混凝土框架结构火灾行为的尺寸效应,对6榀几何相似但比例不同的单层单跨钢筋混凝土平面框架结构开展标准升温条件下的明火试验,然后进行有限元模拟和参数分析,考察柱荷载比和梁荷载比对不同比例框架结构的破坏模式、变形发展... 为探究钢筋混凝土框架结构火灾行为的尺寸效应,对6榀几何相似但比例不同的单层单跨钢筋混凝土平面框架结构开展标准升温条件下的明火试验,然后进行有限元模拟和参数分析,考察柱荷载比和梁荷载比对不同比例框架结构的破坏模式、变形发展以及耐火极限的影响.结果表明:相同受火条件下,几何尺寸和荷载水平相似的不同比例框架的耐火极限存在明显的尺寸效应,随试件尺寸增大,耐火极限增加,但增幅小于按文献中构件的耐火极限相似(或等效)关系推测出的增幅;火灾下钢筋混凝土平面框架结构的破坏模式受梁荷载比、柱荷载比的相对大小影响,当柱荷载比较小、梁荷载比较大时,易发生梁破坏,反之易发生柱破坏;由于混凝土柱的高温性能尺寸效应比混凝土梁的更显著,当小尺寸框架发生柱破坏时,几何和荷载水平相似的大尺寸框架可能发生梁破坏. 展开更多
关键词 钢筋混凝土框架 明火试验 有限元模拟 耐火极限 尺寸效应
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考虑行车安全的制动率界定
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作者 于春鹏 王革新 《交通科技与经济》 2025年第3期76-82,共7页
为更好地理解和运用“制动率”及其合理限值,以行车安全为前提,在阐述刚性摩擦与黏弹性摩擦基础上,分析道路摩擦系数与路面附着系数的异同,比较道路试验与台架试验差异,阐明路试法与台试法对制动力测量的不同,进而确定可能的制动率限值... 为更好地理解和运用“制动率”及其合理限值,以行车安全为前提,在阐述刚性摩擦与黏弹性摩擦基础上,分析道路摩擦系数与路面附着系数的异同,比较道路试验与台架试验差异,阐明路试法与台试法对制动力测量的不同,进而确定可能的制动率限值界定范围。对滚筒反力式汽车制动检验台结构及工作原理进行分析,阐明制动率超过100%的原因及可能性,并以调研数据和试验为验证依据,明确汽车制动性能检验中制动率的标准限值界定范围。研究表明,汽车制动率的标准限值应明确界定,实测中制动率上限值始终小于100%,而制动率的下限值能否达标则与检测设备精度有关。由此可知,制动率上限值应设定为小于100%,而其下限值则应遵守国标GB 7258规定。 展开更多
关键词 汽车工程 制动率 比对分析 台试检验 附着系数 标准限值
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基于增强条件独立性检验的鲁棒因果发现算法
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作者 郝志峰 汪菲霞 +2 位作者 陈正鸣 乔杰 蔡瑞初 《软件学报》 北大核心 2025年第9期4134-4152,共19页
因果关系发现旨在从观测数据中发现变量间的因果关系,是帮助我们理解自然界、社会和技术系统中各种现象和变化的重要方法.一种主流的因果发现方法是基于约束的算法,这类算法通过检验变量间的条件独立性关系来确定变量之间的因果结构.然... 因果关系发现旨在从观测数据中发现变量间的因果关系,是帮助我们理解自然界、社会和技术系统中各种现象和变化的重要方法.一种主流的因果发现方法是基于约束的算法,这类算法通过检验变量间的条件独立性关系来确定变量之间的因果结构.然而,现实世界的数据收集往往受资源或技术的限制,面临样本量有限,节点方差大等挑战.在这些场景下,条件独立性检验的正确率受到极大影响,导致学到的因果图中部分变量的因果边被错误地删除,影响了算法输出的准确性.为此,提出一种增强的条件独立性检验的方法,该方法的核心在于尽可能减少无关外部噪声对于待测试变量的干扰,从而提高条件独立性检验结果的准确性.基于该增强的条件独立性检验方法,提出一种基于启发式搜索的结构学习算法,该算法在初始结构图的基础上,迭代搜索被误删的因果边,基于增强的条件独立性检验并结合得分优化的思想,重构因果结构.实验结果显示,相较于现有方法,所提算法在仿真数据、贝叶斯网络数据以及真实数据上的F1值和结构汉明距离(SHD)均有显著提升,证明在有限样本和因果结构中存在高方差节点的条件下更准确地揭示观测数据中潜在的真实因果结构的能力. 展开更多
关键词 因果结构学习 有限样本量 高方差节点 增强条件独立性检验
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