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71.
In this study, missing value analysis and homogeneity tests were conducted for 267 precipitation stations throughout Turkey. For this purpose, the monthly and annual total precipitation records at stations operated by Turkish State Meteorological Service (DMI) from 1968 to 1998 were considered. In these stations, precipitation records for each month was investigated separately and the stations with missing values for too many years were eliminated. The missing values of the stations were completed by Expectation Maximization (EM) method by using the precipitation records of the nearest gauging station. In this analysis, 38 stations were eliminated because they had missing values for more than 5 years, 161 stations had no missing values and missing precipitation values were completed in the remaining 68 stations. By this analysis, annual total precipitation data were obtained by using the monthly values. These data should be hydrologically and statistically reliable for later hydrological, meteorological, climate change modelling and forecasting studies. For this reason, Standard Normal Homogeneity Test (SNHT), (Swed-Eisenhart) Runs Test and Pettitt homogeneity tests were applied for the annual total precipitation data at 229 gauging stations from 1968 to 1998. The results of each of the testing methods were evaluated separately at a significance level of 95% and the inhomogeneous years were determined. With the application of the aforementioned methods, inhomogeneity was detected at 50 stations of which the natural structure was deteriorated and 179 stations were found to be homogeneous.  相似文献   
72.
73.
Here, a soft robotic microgripper is presented that consists of a smart actuated microgel connected to a spatially photopatterned multifunctional base. When pressed onto a target object, the microgel component conforms to its shape, thus providing a simple and adaptive solution for versatile micromanipulation. Without the need for active visual or force feedback, objects of widely varying mechanical and surface properties are reliably gripped through a combination of geometrical interlocking mechanisms instantiated by reversible shape‐memory and thermal responsive swelling of the microgel. The gripper applies holding forces exceeding 400 µN, which is high enough to lift loads 1000 times heavier than the microgel. An untethered version of the gripper is developed by remotely controlling the position using magnetic actuation and the contractile state of the microgel using plasmonic absorption. Gentle yet stable robotic manipulation of biological samples under physiological conditions opens up possibilities for high‐throughput interrogation and minimally invasive interventions.  相似文献   
74.
Dolomite is an alternative material for producing precipitated calcium carbonate (PCC) particles, which have widespread industrial applications depending on their morphology and particle sizes. These properties are readily controlled by the production conditions such as reaction time, temperature, stirring speed, and CO2 flow rate. In this paper, we investigate the influences of these experimental conditions on the production of synthetic aragonite crystals from dolomite using a leaching carbonation process. The proposed process is believed so be more eco-friendly than other methods suggested in the literature because the CO2 released from the dolomite during the leaching stage is stored for use in the carbonation stage. The experimental results indicate that the morphology of the produced PCC is influenced not only by the reaction time and temperature, but also the stirring speed and CO2 flow rate. The required reaction time decreases with an increase in the CO2 flow rates. However, calcite forms along with the aragonite crystals at higher CO2 flow rates. We successfully synthesized pure aragonite crystals in the reaction temperature range of 40–70 °C at a fixed CO2 flow rate of 3.00 l/min, and at a stirring speed of 750 rpm. The d90 values of the aragonite crystals at various temperatures ranged from 18.47 to 25.99 μm. We fit the experimental results by a single-term exponential model.Additionally, we obtained a Mg-rich solution and CO2 gas as by-products, which are in high demand.  相似文献   
75.
氮氧化物是造成全球变暖和产生酸雨的主要物质,因此氮氧化物气体的检测在环境监测和化学工业等许多领域中具有重要意义.该文以甲基绿为敏感试剂,将其掺杂于聚乙烯醇溶液后固定在钾离子玻璃光波导上,研制出检测氮氧化物气体的高灵敏度光波导传感元件.该元件具有响应快、成本低、易制作等特点.可检测出浓度为1.91 mg/m3的二氧化氮气体.  相似文献   
76.
Eksioglu M 《Ergonomics》2006,49(2):180-201
The aim of this study was to investigate the maximum acceptable contraction frequencies (i.e. work-rest cycles) for an isometric-intermittent handgrip task as a function of grip span, applied force and shoulder posture using psychophysical and physiological approaches. Twelve healthy males served as subjects. The three grip spans investigated were the optimal, 2 cm narrower than the optimal, and 2 cm wider than the optimal. The grip force levels studied were 15% and 30% of maximum voluntary grip force and the two shoulder postures were 25 degrees flexion and 30 degrees abduction. The psychophysical results indicate that subjects work faster with the narrower grip span at 15% of maximum voluntary grip force level in comparison to working with the optimal and the wider spans. However, when the task required 30% of maximum grip force level, the subjects worked faster with the optimal grip span. These findings were supported by the results of electromyography, heart rate, blood pressure and perceived discomfort. The study suggests that grip span of a tool is an important factor to be considered in predicting optimal work-rest cycles for hand grip tasks, and the optimum setting of grip span of the hand-tool depends on the required task force level. That is, the optimality is relative rather than absolute. In addition, it appears that weaker subjects can work at a higher rate than stronger ones at the same relative force level.  相似文献   
77.
西伯利亚花楸枝条提取物抑菌作用的测定   总被引:1,自引:0,他引:1  
为了研究西伯利亚花楸枝条乙醇提取物的体外抑菌特性,测定了提取物对一系列供试细菌和真菌的最低抑菌浓度、最低杀菌浓度,以金黄色葡萄球菌及大肠杆菌为例研究了提取物的热稳定性、紫外光稳定性,以金黄色葡萄球菌为例研究了提取物抑菌时间及抑菌率的关系,同时还进行了实物防腐实验.结果表明提取物对所有供试细菌及真菌都有明显的抑制作用,其最低抑菌浓度(MIC)较低;121℃湿热处理30min后,抑菌效应下降不大,具有良好的热稳定性及紫外光稳定性,其抑菌作用随抑菌时间的延长而增强,实物防腐实验效果良好.  相似文献   
78.
The adsorption of malachite green onto bentonite in a batch adsorber has been studied. The effects of contact time, initial pH and initial dye concentration on the malachite green adsorption by the bentonite have been studied. Malachite green removal was seen to increase with increasing contact time until equilibrium and initial dye concentration, and the adsorption capacity of bentonite was independent of initial pH in the range 3–11. Four kinetic models, the pseudo first- and second-order equations, the Elovich equation and the intraparticle diffusion equation, were selected to follow the adsorption process. Kinetic parameters; rate constants, equilibrium adsorption capacities and correlation coefficients, for each kinetic equation were calculated and discussed. It was shown that the adsorption of malachite green onto bentonite could be described by the pseudo second-order equation. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich equations. Adsorption of malachite green onto bentonite followed the Langmuir isotherm. The thermodynamic parameters, such as ΔH, ΔS and ΔG, were also determined and evaluated. A single stage batch adsorber was designed for different adsorbent mass/treated effluent volume ratios using the Langmuir isotherm.  相似文献   
79.
We adopt an individual-differences perspective and introduce a model that links types of biases and types of people. We propose that biases are created in the course of people’s attempts to satisfy basic motivations, and that 3 such motivation categories underlie many of the biases discussed in the literature. Accordingly, our organizing framework integrates findings from previous research and classifies biases into verification biases, simplification biases, and regulation biases. Individual differences in core self-evaluations, in approach/avoidance temperament, and in cognitive ability and style help explain how biases come about and why some people are more likely than others to exhibit particular biases. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
80.
利用旋转甩涂法在钾离子交换玻璃光波导表面上固定甲基绿/聚乙烯醇薄膜,成功地检测氯仿蒸汽。实验结果表明,该元件对氯仿蒸汽有良好的响应,其线性响应范围为10×10-3~90×10-3(R=0.98674)。该元件具有响应恢复速度快、可逆性好、成本低和易制备等特点。  相似文献   
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