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551.
高密度电法是常用的物探方法,在水库大坝探测方面也经常用到.文中介绍了高密度电法的原理和反演分析方法,采用高密度电法对霍林河水库大坝渗漏情况进行了探测试验,采用"单极-单极"阵列方式分别对大坝的4个断面进行了渗漏探测试验,并结合实测资料分析大坝渗漏原因.试验结果表明:高密度电法有效地探测了霍林河水库大坝渗漏情况,检验了防渗处理的效果,为大坝防渗加固提供了依据,也进一步验证了高密度电法在水库渗漏探测中具有较好的效果. 相似文献
552.
刘易斯拐点的到来导致中国劳动力成本大幅上升,这使得如何避免员工主动离职成为保证企业人力资源稳定的核心问题。针对离职行为这一复杂系统,从实证研究与突变理论相结合的全新视角,构建了员工主动离职的突变概念模型。在此基础上引入定性模拟算法,提出了突变函数在离职行为研究中的参数估计方法,并通过长三角地区某企业的实际案例验证了该方法的合理性及鲁棒性。最后,根据经济转型期的"离职潮",对员工主动离职的定性-定量混合突变模型进行虚拟实验分析。实验结果从精确测定员工离职的预警区、临界区和突变区及复杂经济环境与员工离职的关系,以及企业微观层面和政府宏观层面的控制策略等方面,为员工主动离职问题提供了决策支持。 相似文献
553.
Fu Xu Xiaolong Mo Sen Wan Changqing Jiang Hongwei Hao Luming Li 《科学通报(英文版)》2014,(29):3831-3834
Carbon nanotube yarns (CNTY) possess good specific strength and specific conductivity. As such, their potential for commercial applications is significant. Fatigue performance is a significant consideration in yarn/wire applications. In this study, the flexural fatigue performance of CNTY spun from super-aligned carbon nanotube arrays was investigated using a reversed bending test. The results showed that CNTY exhibited excellent resistance to pure flexural fatigue, significantly outperforming stainless steel wire; CNTY failed where a combination of flexural fatigue and tension-tension fatigue had special hollow fracture morphology, and CNTY resistance remained fundamentally unchanged in the combination fatigue process. 相似文献
554.
555.
The influence of home environmental factors and life style on children's respiratory health in Xi'an
To assess associations between home indoor air environments and asthma,allergies and pneumonia,children aged 1–8 years were surveyed from 12 kindergartens in the city of Xi’an.2,020 questionnaires were responded with a response rate of 83.5%.The prevalences of doctor diagnosed asthma,hay fever,and pneumonia were 2.9%,3.6%,and 28.3%,respectively.Living close to a highway was a risk factor for current rhinitis(AOR 1.5,95%CI 1.2–1.8),eczema(AOR 1.7,95%CI 1.2–2.5),and diagnosed pneumonia(AOR 1.3,95%CI 1.0–1.6).Dampness problems in the home were associated with 50%–130%increases in the prevalences of asthma and allergy.Airing bed linen under sun-shine was protective,especially against rhinitis.Pet avoidance was consistently and significantly associated with asthma and allergy(AOR 1.3–2.4).Decoration of the home during children’s early life is a risk factor for current rhinitis(AOR 1.9,95%CI 1.3–2.9)and eczema(AOR 1.9,95%CI1.1–3.6).Risk factors for pneumonia were living in an apartment(AOR 1.4,95%CI 1.1–1.8),latex wall paint(AOR 1.3,95%CI 1.0–1.7),dampness(AOR 1.4–1.5),breast feeding\3 months(AOR 1.3,95%CI 1.0–1.7),never airing bed linen in sunshine(AOR 1.3,95%CI1.3–1.6),and cleaning children’s room less frequently than once per day(AOR 1.4,95%CI 1.1–1.7).This study demonstrates that home indoor environmental and life style factors may influence the health of children in Xi’an. 相似文献
556.
Lei Shen Zhiwen Liu Xiaoming Gou Yougen Xu 《系统工程与电子技术(英文版)》2014,(6):942-948
A polynomial-rooting based fourth-order cumulant algorithm is presented for direction-of-arrival(DOA) estimation of second-order fully noncircular source signals, using a uniform linear array(ULA). This algorithm inherits all merits of its spectralsearching counterpart except for the applicability to arbitrary array geometry, while reducing considerably the computation cost.Simulation results show that the proposed algorithm outperforms the previously developed closed-form second-order noncircular ESPRIT method, in terms of processing capacity and DOA estimation accuracy, especially in the presence of spatially colored noise. 相似文献
557.
558.
Compared with standard logit-based stochastic user equilibrium assignment model, the C-logit model describes route choice behavior in a more realistic way by considering the overlapping effect between routes. This paper investigates the inefficiency upper bounds of this model against the deterministic system optimum and the C-logit stochastic system optimum in terms of the total network travel time. It is found that the commonality factor of overlapping routes significantly affects the inefficiency bound, besides link congestion degree, total demand and the number of feasible routes. If the commonality factor is not considered, the efficiency loss resulting from selfishly stochastic travel behavior will be to large extent underestimated. 相似文献
559.
为了研究不同消毒时间、不同浸种时间和不同培养基配方对金钱松种子萌发的影响.金钱松种子采用75%酒精消毒30 s和0.1%升汞消毒15 min,用40℃无菌水浸泡12 h后,接种在不添加任何激素的MS培养基上,其种子的萌发率最高为64.5%,且幼苗生长也好. 相似文献
560.