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451.
通过高应变动力试桩法来获得桩土参数是目前比较流行的试桩方法,其原理主要是通过以桩顶的实测信息来反演桩土参数,其中比较成熟的CAPW APC法主要用试凑法来反演桩土模型参数,其反演结果呈现一定的随机性且正确性过于依赖操作者经验。本文尝试以CAPW APC法所采用比较成熟的桩土模型为基础,引入基于最佳摄动量法的局部优化方法来反演桩土参数。在弹性波波动方程隐式差分的基础上,对反演参数采用摄动展开并推导出参数反演的递推公式,最后给出合适的反演算法。考虑到初始参数对局部优化方法的影响,根据场地的实际情况选取合适的初始模型,计算显示可以获得比较理想的结果,说明本法是对桩基动测方法的一种有效的新尝试。 相似文献
452.
With the collectivization of the Chinese oil industry, oil companies have been expanding in size. However, the intensified differences in the safety performance of subsidiaries have severely hindered the collaborative management of the headquarters. Understanding the safety status of each member is urgent for parent companies and their subsidiaries to identify gaps and make improvements. A unified set of safety performance indicators and a practical measurement tool are essential for the Chinese oil industry. Hence, this study identified a set of safety performance indicators encompassing both leading and lagging indicators using data envelopment analysis (DEA) and entropy weight method (EWM) to reveal the critical factors affecting the safety performance of the oil industry. A total of 300 front-line workers from eight subsidiaries of an oil company participated in the survey. The identified indicators were preliminarily weighted using EWM. Then, DEA was employed to measure the safety performance of the eight subsidiaries, demonstrating that management commitment was the most crucial factor in distinguishing safety performance; safety culture was more differentiated than risk management. Safety performance was not entirely positively correlated with safety investments, but the reasonable allocation of safety resources played a vital role. In addition, the weaknesses in each subsidiary's safety management were identified, and the quantitative effects of each leading indicator on safety performance were obtained. 相似文献
453.
454.
利用6种数据挖掘算法对2012年台风和污染物浓度等数据建模,建立台风条件下的气象因素和环境空气中PM2.5的关系模型。通过对2013年数据的测试,表明6种数据挖掘方法模型的预测值与实测值具有很好的一致性。6种算法均能实现实时预测,其中Bagging算法预测结果的相关性整体最好,而对于测试样本,M5Rules算法最好,SMOreg算法次之。以2013年的超强台风"海燕"的预测为例,讨论台风条件下PM_(2.5)质量浓度的变化过程及对预测结果的解释。 相似文献
455.
Rapid economic growth and urbanization in China have resulted in great water consumption in recent years. China has been facing increasingly severe water shortage crisis, especially in urban areas. This paper focuses on performance analysis for regional urban water use and wastewater decontamination systems in China. To this end, a DEA-based approach is developed. In the proposed approach, the efficiency of the system is decomposed into water use efficiency and wastewater decontamination efficiency. In the wastewater decontamination sub-system, the purified wastewater (reusable water) is treated as a desirable output; while in the water use sub-system, it is incorporated as a fixed input, which cannot be decreased in the process of efficiency optimization. The efficiency of the system is defined as the average of the two sub-systems’ efficiencies. The proposed approach can find inefficiencies caused by the internal factors between sub-systems, which cannot be identified using the traditional DEA approaches. We finally apply the proposed approach to analyze the efficiencies of regional urban water use and wastewater decontamination systems in China. Based on the application results, some findings and implications for efficiency improvement of urban water management in China are achieved. 相似文献
456.
洪宝德 《防灾减灾工程学报》1999,(3)
根据杨鉴初的历史演变法原理,对苏皖沪(30°~36°N,115°~125°E)1971 ~1997 年最大震级( MS) 形成的时间序列,先进行迭次平滑,再据这些逐趋光滑的地震活动历史演变曲线的外形特征及数值,找出它们之间的联系规律与各自的变化规律:超前性、近似性、准对称性与渐变性。并根据这些规律性制成时间序列演变曲线板:近似板、旋转板与折迭板,对逐年最大震级进行外延验证,以及对1998 年的最大震级做出预报。结果表明:用演变曲线板量取的时间序列外延预报值,与实况的差值都能小于|0 .5| 级。 相似文献
457.
以上海嘉定区环境空气自动监测数据为依据,利用中美合作-上海市环境空气质量发布系统示范项目(AIRNOW-International)提供的DMS数据自动审核模块,结合市区两级人工审核系统,对数据有效性审核中的异常数据情形进行归类和总结。以实例的方式介绍了环境空气常规六参数常见的异常数据情形,并提出应对异常数据的审核程序和办法。 相似文献