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71.
城市热环境变化影响城市小区域气候,探究影响因子与其作用机制,可有效减缓城市热岛现象。利用郑州市1960~2017年长序列数据,从相对热岛(RHI)和绝对热岛(AHI)两个层面探究驱动因子降雨(R)、蒸发(E)、建成区面积(BBUA)、城镇化率(UUR)的影响关系,利用交叉小波和小波相干探究热岛与降雨的雨热关系,采用Copula函数计算影响因子在不同取值条件下与热岛的遭遇概率。结果表明,相对热岛-相对降雨在短中周期、绝对热岛-降雨在短周期上均呈负相关关系,雨热关系不同步,且绝对热岛-降雨的关系最为显著;影响因子BBUA、UUR取值越大,R取值越小,则与RHI、AHI的遭遇概率越大;不同影响因子在不同评价层面,敏感性强弱不同,E在不同层面的反馈机制也不同,可见选取合适评价分析层面,有利于准确量化影响程度。 相似文献
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《Journal of dairy science》2022,105(7):6094-6110
In recent years, interest has been increasing in whether farmed animals are able to live a reasonably natural life, with one particular area of concern being calf-dam separation. The objectives of this study were to monitor the timing and frequency of suckling behavior of calves left on pasture to suckle their dams for up to 24 h (interquartile range 4.0–15.5 h) and to investigate possible risk factors that may contribute to any variability seen. Over 2 yr, a convenience sample of 8 farms (4 in the North Island, 4 in the South Island of New Zealand) were involved in an observational study where cows and calves were observed for 24 h a day over a 2-wk-long period per farm. During the observation period, farmers continued to remove calves at the same frequency they normally did (which ranged from once a day to 4 times a day). Cows (between 2 and 12 yr old) and calves were observed from a scissor lift in or beside the calving paddock. Cows had numbers written on them, and observers used binoculars and spotlights. Observers recorded the length of stage 2 labor, time of birth, standing, and first suckling, number of suckling events, time of calf removal from the dam, temperature where the cows were grazing, and size of the grazing area they were calving in. Dams were body condition scored before calving, and their age was extracted from farm records. A total of 697 calves were observed during the study. A total of 444 of 697 calves [63.7%; 95% confidence interval (CI) = 60.0–67.3%] suckled in the calving paddock (farm range 40.0% to 90.2%). Of the 444 calves that suckled in the calving paddock, 407 (58.4%; 95% CI 54.6–62.1%) suckled within the first 6 h after birth (farm range 33.0% to 83.6%). Individual risk factors associated with the hazard rate ratio (HR) for time to first suckling event were time to standing (calves who took more than 1.3 h to stand had a longer time from birth to first suckle) and age of the dam [compared with calves that were born from dams >7 years of age, calves born to dams that were 2–3 and 4–7 yr of age had a 1.49 (95% CI 1.07–2.06) and 1.19 (95% CI 0.89–1.60) HR, respectively, for time from birth to first suckle in the calving paddock]. Farm risk factors associated with the HR of suckling were frequency of calf collection [calves that were born on farms that collected calves once a day suckled earlier than calves on farms that removed calves more than once a day (HR 1.52; 95% CI 1.25–1.84)] and temperature [a minimum temperature of <10°C within 6 h of a calf being born was associated with a 0.69 (95% CI 0.53–0.89) hazard of suckling in the calving paddock]. We observed very large farm variability that urgently requires further investigation if pasture-based farms are ever to adopt a system where calves remain with their dams for longer than 24 h. 相似文献
75.
利用浓缩因子区划矿井富水性 总被引:4,自引:0,他引:4
电阻率浓缩因子是相邻多个极距视电阻率之和与其中最小值之比,是在电阻率差异较小,无法解释时的一种数据处理方法,该方法突出有用异常、压制干扰性能较强。论文以郭二庄煤矿下架煤层涌水为例,研究了浓缩因子的求取方法和分区原则,利用浓缩因子将其底部奥陶系地下水富水性划分为三个区,并论证其划分的可靠性。 相似文献
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77.
影响综合机械化采煤的因素分析 总被引:4,自引:0,他引:4
总结和分析了影响综合机械化采煤的煤层厚度、煤层倾角、煤层顶底板、煤层机构的破坏等因素。 相似文献
78.
文对我国延期雷管秒量精度低的问题,从延期药剂组成及制造工艺、点火药及点火药头作用、延期雷管结构及外界环境条件的影响等方面进行了综述,认为主要影响因素是由延期药剂为主构成的延期元件,提出在发展电子延期技术的同时,仍有必要做好延期药优化和加工技术研究与应用。 相似文献
79.
金刚石绳索取心钻进施工效率影响因素分析 总被引:1,自引:0,他引:1
张伟 《探矿工程(岩土钻掘工程)》2007,34(10):22-24,34
采用技术经济学研究方法,对一些影响金刚石绳索取心钻进施工效率的钻探技术指标,如机械钻速、回次长度、起下钻速度、起钻间隔进行了分析和评价。通过了解这些因素在不同钻孔深度条件下对钻进施工效率影响作用的大小,可为钻探项目的设备、器具和钻进工艺方法选择提供依据。 相似文献
80.
砂土液化影响因素及其判别方法 总被引:12,自引:0,他引:12
砂土液化受动荷条件、埋藏条件和土性条件的制约,在进行砂土液化判别时不能从某一方面或某一统计公式简单评判。综合考虑各影响因素,采用多因子判别分析法加以判别。 相似文献