防雷接地装置腐蚀影响因素的层次分析法

防雷接地装置是保证防雷系统正常运行的基础,然而,它不可避免会受到土壤的腐蚀。首先对防雷接地装置腐蚀机理进行了论述;其次通过整理、分析文献资料,合理选取影响防雷接地装置腐蚀的主要因素;然后根据腐蚀因素参与腐蚀的程度,构建层次分析模型,利用模型对腐蚀因素进行定量分析,界定出影响因素对防雷接地装置腐蚀影响的权重值;最后对腐蚀因素进行综合排序。研究表明,影响防雷接地装置腐蚀的最主要因素为pH值、土壤电阻率和含水量,这为制定经济合理、安全可靠的防雷接地装置腐蚀防护措施提供了科学依据,具有实际工程应用价值。     

The input efficiency of chord keyboards

This study focused on an innovative mobile input device model that integrated ergonomic design principles to create a chord keyboard for use in concert with pointing devices. We conducted usability tests to demonstrate the operating performances of such keyboards using keys with four characters per key. Twelve right-handed subjects between the ages of 20 and 30 years and with no wrist disability participated in the usability tests. We analyzed the resulting data to compare the differences among the means. The results indicated that keyboards with multiple characters per key created some confusion among users but that keys with multiple characters per key nonetheless resulted in better input performance.     

Simulated Limnological Effects of the Shasta Lake Temperature Control Device

We estimated the effects of a temperature control device (TCD) on a suite of thermodynamic and limnological attributes for a large storage reservoir, Shasta Lake, in northern California. Shasta Dam was constructed in 1945 with a fixed-elevation penstock. The TCD was installed in 1997 to improve downstream temperatures for endangered salmonids by releasing epilimnetic waters in the winter/spring and hypolimnetic waters in the summer/fall. We calibrated a two-dimensional hydrodynamic reservoir water quality model, CE-QUAL-W2, and applied a structured design-of-experiment simulation procedure to predict the principal limnological effects of the TCD under a variety of environmental scenarios. Calibration goodness-of-fit ranged from good to poor depending on the constituent simulated, with an R ² of 0.9 for water temperature but 0.3 for phytoplankton. Although the chemical and thermal characteristics of the discharge changed markedly, the reservoir's characteristics remained relatively unchanged. Simulations showed the TCD causing an earlier onset and shorter duration of summer stratification, but no dramatic affect on Shasta's nutrient composition. Peak in-reservoir phytoplankton production may begin earlier and be stronger in the fall with the TCD, while outfall phytoplankton concentrations may be much greater in the spring. Many model predictions differed from our a priori expectations that had been shaped by an intensive, but limited-duration, data collection effort. Hydrologic and meteorological variables, most notably reservoir carryover storage at the beginning of the calendar year, influenced model predictions much more strongly than the TCD. Model results indicate that greater control over reservoir limnology and release quality may be gained by carefully managing reservoir volume through the year than with the TCD alone. RID=" ID=" Author to whom correspondence should be addressed. e-mail: John_Bartholow@USGS.gov     

水和废水中硫化物测定预处理装置的改进

本文对亚甲基分光光度法测定水质硫化物的预处理装置进行了改进。实验结果表明改进的预处理装置效果与GB／T16489--1996等同，装置简单，操作简便、快速,吹气吸收效果好。     

铝电解含氟烟气治理技术

铝电解过程中产生大量含氟烟气，主要介绍目前国内几家铝厂所采用的含氟烟气治理技术，并对实际工作中存在的问题进行分析，供在类似工程中参考借鉴     

三级以上海况海面油膜厚度测定装置的研制

本文描述了３级以上海况（３￣５级）海面油膜厚度测定的非光学装置，该装置由敝开一封闭式油膜采样器和降集增厚器组成。为适应恶劣海况情况下采集油膜，保证数据的可靠性，该装置增加了防止油膜外溢的机构及原始平行样采样管，海上现场试验分别以零号轻柴油、海军燃料油、混合油为对象，测定厚度为１００￣１０００μｍ的油膜。并对多次采样的测定值进行了数理统计。该装置现场测定的相对误差≤±２４．５％。     

电梯制动器机械装置提起（或释放）验证的研究

为确保电梯制动器检测开关能够准确检测电梯制动器机械装置提起（或释放）的异常,消除异常造成的危险情况,结合电梯制动器的型式和检测开关的动作原理,对各种检测开关接线方式进行分析,针对制动器的型式提出了合理的制动器检测开关接线方式。研究结果表明:直压式制动器可用1个通断状态的检测开关对其机械装置的提起（或释放）进行验证,但应在电梯的主板上设置2个检测点;杠杆式鼓式制动器应用具备2个通断状态的检测开关对其机械装置的提起（或释放）进行验证,且应采用常开并联或常闭串联的方式检测制动器机械装置的释放,采用常闭并联和常开串联的方式检测制动器机械装置的提起。     

MAGNETIC TRIGGER FOR AUTOMATIC PUMPING SAMPLERS1

ABSTRACT: A stage-activated triggering device was developed for automatic pumping samplers. The device consists of a proximity switch and ten magnets mounted radially at equal intervals on a plexiglass disk. The triggering device allows discrete sampling of stream water at 3.0 cm intervals of stage. The trigger proved dependable during two years of use at three headwater streams in the Ouachita Mountains of southeastern Oklahoma.     

城市生活垃圾中转站举升装置设计与应用

对地平式城市垃圾中转站的 3种举升装置进行了详细分析 ,指出了其存在的问题 ,提出了一种新型的链条式城市垃圾中转站举升装置 ,它结构紧凑 ,运行平稳可靠 ,成本低 ,噪音小 ,节能省电 ,是垃圾中转站新型优选产品 ,现已成功应用于环卫工程中