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焊接钢丝网水泥在一种模拟污水环境中的疲劳特性 被引量:2
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作者 熊光晶 g.singh 《土木工程学报》 EI CSCD 北大核心 1997年第4期43-50,共8页
本研究首先使114个焊接钢丝网水泥试件承受长达3年的静弯曲与模拟污水腐蚀的共同作用,进而再对这些试件进行腐蚀疲劳实验.结合钢丝网水泥壁薄的特点对实验结果进行合理的修正.采用改进的P-S-N(破坏概率-应力水平-疲劳寿命)方法,评估了... 本研究首先使114个焊接钢丝网水泥试件承受长达3年的静弯曲与模拟污水腐蚀的共同作用,进而再对这些试件进行腐蚀疲劳实验.结合钢丝网水泥壁薄的特点对实验结果进行合理的修正.采用改进的P-S-N(破坏概率-应力水平-疲劳寿命)方法,评估了钢丝网水泥抗腐蚀疲劳性能.建议以P-S-N关系作为受腐蚀疲劳的钢丝网水泥构件的设计依据. 展开更多
关键词 钢丝网水泥 污水管道 腐蚀疲劳试验 疲劳寿命
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一种改进的评估疲劳特性的P-S-N方法
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作者 熊光晶 崔玉清 g.singh 《应用力学学报》 CAS CSCD 北大核心 1999年第1期127-130,共4页
提出一种改进的P-S-N(破坏概率-应力水平-疲劳寿命)方法,从而扩展了这一方法的应用范围。指出建立P-S-N关系时,应包含经200万次荷载作用不破坏而停止试验的试件。
关键词 弯曲疲劳 破坏概率 应力 疲劳寿命 P-S-N方法
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镀锌焊接钢丝网水泥在一种模拟海洋环境中的疲劳特性
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作者 熊光晶 L.IP g.singh 《哈尔滨建筑大学学报》 1999年第1期43-47,共5页
使正常养护28d的70个镀锌焊接钢丝网水泥试件持续受弯,最外层钢丝的计算应力达到腐蚀状态下容许值207N/mm2,再放入自制的以70℃干燥60min和40℃3.5%NaCl溶液浸渍30min为一周期的快速模拟海洋环境实验系统中,分别承受荷载一腐蚀共... 使正常养护28d的70个镀锌焊接钢丝网水泥试件持续受弯,最外层钢丝的计算应力达到腐蚀状态下容许值207N/mm2,再放入自制的以70℃干燥60min和40℃3.5%NaCl溶液浸渍30min为一周期的快速模拟海洋环境实验系统中,分别承受荷载一腐蚀共同作用1、3、7和18个月(480-8640个周期),再对这些试件进行弯曲疲劳-腐蚀试验。分析评估了影响钢丝网水泥抗荷载-腐蚀性能的因素,给出了破坏概率-应力水平-疲劳寿命(P-S-N)关系,指出不必计算裂缝宽度. 展开更多
关键词 钢丝网水泥 腐蚀 弯曲疲劳 海洋环境
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Evaluation of trend in semen analysis for 11 years in subjects attending a fertility clinic in India 被引量:10
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作者 P.Marimuthu M.C.Kapilashrami +1 位作者 M.M.Misro g.singh 《Asian Journal of Andrology》 SCIE CAS CSCD 2003年第3期221-225,共5页
Aim: The data on semen analysis of subjects attending the Fertility Clinic at NIHFW (National Institute of Health and Family Welfare) Munirka, New Delhi for the last 11 years were analyzed to verify the claims and spe... Aim: The data on semen analysis of subjects attending the Fertility Clinic at NIHFW (National Institute of Health and Family Welfare) Munirka, New Delhi for the last 11 years were analyzed to verify the claims and speculations on declining sperm counts in men. Methods: Approximately 10 % of the records every year starting from 1990 to 2000 (numbering 1176 in total) were randomly selected for analysis. Subjects with azoospermia or severe oligozoospermia were excluded from analysis. Results: The average age of the men attending the infertility clinic was 31.2 years. The average semen volume and sperm count were found to be (2.6 ±0.1) mL and (60.6 ± 0.9) × 106/mL, respectively. No significant decline in sperm counts was observed in any year during the entire study period. Only 1.8 % of the total number of sperm counts in the random sampling were less then 20 × 106/mL. On the basis of WHO criteria on motility, the total percentage of non-progressive and non-motile sperm in the ejaculate was higher (63 %) as compared to the combined categories of slow and rapid linear progressive. Conclusion: The present study has confirmed similar findings from other different countries that declining sperm counts in humans is not a global phenomenon. 展开更多
关键词 semen analysis sperm motility declining sperm count male infertility
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Application of seminal germ cell morphology and semen biochemistry in the diagnosis and management of azoospermic subjects 被引量:4
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作者 Somnath Roy A.Banerjee +2 位作者 H.C.Pandey g.singh G.L.Kumari 《Asian Journal of Andrology》 SCIE CAS CSCD 2001年第1期55-62,共8页
Aim: To evaluate whether the study of seminal germ cell morphology (SGCM) and semen biochemistry could befruitfully utilized for the diagnosis and management of azoospermic subjects. Methods: In the semen, mature andi... Aim: To evaluate whether the study of seminal germ cell morphology (SGCM) and semen biochemistry could befruitfully utilized for the diagnosis and management of azoospermic subjects. Methods: In the semen, mature andimmature germ cells are contributed by the testes, 70% of glycerylphosphoryl choline (GPC) by the epididymis, fruc-tose mostly or solely by the seminal vesicles and acid phosphate (ACP) by the prostate. In 16 normal volunteers, 12vasectomized subjects and 186 azoospennic subjects, these parameters have been studied and the data have been ana-lyzed. Results: Both mature and immature germ cells are absent in the semen of vasectomized subjects as well as inobstructive azoospennia; GPC level is also significantly decreased in both these groups. In cases with non-obstructiveazoospermia immature germ cells are present and seminal GPC, ACP and fructose levels are normal. The diagnosis ofobstructive and non-obstructive azoospermia based on these parameters correlated well with 'correct' testicular biopsyfindings. In some cases of azoospermia due to hypospermatogenesis or spermatogenic developmental arrest, the SGCMstudies were very helpful in objectively monitoring the response of the germinal tissue to specific treaunents. Conclu-sion: SGCM and semen biochemical parameters are very valuable non-invasive markers for differentiating obstructivefrom non-obstructive azoospermia. The SGCM findings serve as a dependable non-invasive testicular marker with highpredictive value. (Asian J Androl 2001 Mar; 3: 55-62) 展开更多
关键词 AZOOSPERMIA SEMEN BIOCHEMISTRY germ cells intracytoplasmic sperm injection
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Screening Azadirachta indica tree for enhancing azadirachtin and oil contents in dry areas of Gujarat,India 被引量:4
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作者 U.K.Tomar g.singh N.Kaushik 《Journal of Forestry Research》 SCIE CAS CSCD 2011年第2期217-224,共8页
Azadirachta indica seed samples were collected from four different agro-ecological regions(AERs) viz.,AER-2,AER-4,AER-5A and AER-5B of Gujarat state,India during 2000 to 2002 with an aim to assess variability in aza... Azadirachta indica seed samples were collected from four different agro-ecological regions(AERs) viz.,AER-2,AER-4,AER-5A and AER-5B of Gujarat state,India during 2000 to 2002 with an aim to assess variability in azadirachtin,oil and fatty acids content of the seeds and assess correlation of these parameters with morphological characters.Azadirachtin,oil and fatty acids content indicated significant(p0.01) variations between years and AERs in Gujarat.The azadirachtin ranged from 142 to 9 527 μg·g-1 seed kernel with an average of 2 426 μg·g-1 for the state.AER-5B recorded highest azadirachtin and oil content.Fatty acid composition was found to be affected by environmental factors particularly varying degree of annual rainfall and temperature during fruit ripening period.Conclusively trees growing in AER-5B performed better in term of azadirachtin,oil and stearic acid content.Tree girth at breast height showed no significant relation with these biochemicals. 展开更多
关键词 agro-ecological zones fatty acids girth-class neem seed VARIABILITY
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Performance analysis of cognitive radio networks using channel-prediction-probabilities and improved frame structure 被引量:1
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作者 Prabhat Thakur Alok Kumar +2 位作者 S.Pandit g.singh S.N.Satashia 《Digital Communications and Networks》 SCIE 2018年第4期287-295,共9页
This paper focuses on potential issues related to the random selection of a sensing channel that occurs after the prediction phase in a Cognitive Radio Network (CRN).A novel approach (Approach-l)for improved selection... This paper focuses on potential issues related to the random selection of a sensing channel that occurs after the prediction phase in a Cognitive Radio Network (CRN).A novel approach (Approach-l)for improved selection is proposed,which relies on the probabilities of channels by which they are predicted idle.Further,closed-form expressions are derived for the throughput of Cognitive Users (CUs)in the conventional and proposed approaches. In addition to this,a fimdamental approach for computing the prediction probabilities is also proposed.Moreover, a new challenging issue named "sense and stuck"was observed in the conventional approach.The proposed approach is validated by comparing the results achieved with the results of the conventional approach.However, to achieve the prediction probabilities,the pre-channel-state-information is a prerequisite,but it may be unavailable for particular scenarios;therefore,a modified selection method is introduced to avoid the sense and stuck problem.An algorithm to evaluate the throughput using the random,improved,and modified selection methods is presented with its space and time complexities.Furthermore,for additional improvement in the throughput of the CU,a new frame structure is introduced,in which the spectrum prediction and sensing periods are exploited for simultaneous transmission of data via the underlay spectrtun access technique (Approach-2).The simulated results of Approach-2 are compared with our pre-obtalned results of Approach-I,which confirm significant improvement in the throughput. 展开更多
关键词 COGNITIVE RADIO Interweave PREDICTION SPECTRUM accessing THROUGHPUT Underlay
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印度北部污染物对雨水中PH值的长期影响
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作者 L.T.Khemani G.A.Momin +6 位作者 P.S.Prakasa Rao P.D.Safai g.singh R.N.Chatterjee Prem Prakash 刘育民 聂明浩 陆贞芝 《江苏环境科技》 1993年第4期45-48,共4页
在阿格拉和德里1963年与1965年夏季季风期间收集的雨水样品中的离子成份和 PH 值同这两个城市在1984年夏天季风期间所收集到的雨水样品分别进行比较,发现阿格拉和德里在二十年之后 PH 值分别降低2.8(9.1—6.3)和0.9(7.0—6.1),此期间两... 在阿格拉和德里1963年与1965年夏季季风期间收集的雨水样品中的离子成份和 PH 值同这两个城市在1984年夏天季风期间所收集到的雨水样品分别进行比较,发现阿格拉和德里在二十年之后 PH 值分别降低2.8(9.1—6.3)和0.9(7.0—6.1),此期间两城市的工业化有了很大的发展。PH 值降低的主要原因是雨水中酸性成份大大增加,来自土壤的成份减少了。这是在印度第一次观察到污染物对雨水 PH 值的长期影响,但是这种影响与西方国家相比是比较慢的。 展开更多
关键词 雨水 酸雨 污染物 印度北方 PH值 样品
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