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排序方式: 共有1209条查询结果,搜索用时 15 毫秒
41.
工业热电偶、热电阻自动检定装置   总被引:1,自引:0,他引:1  
将传统的手动热电偶、热电阻检定装置改进为自动检定装置,实现了自动连续检定。  相似文献   
42.
基于正交极差分析的青龙河流域HSPF模型参数寻优模式   总被引:3,自引:2,他引:1  
为评价桃林口水库水文水质状况,建立其上游青龙河流域的BASINs/HSPF水文水质模拟模型.以Nash-Sutcliffe效率系数作为评价标准,联合正交设计和极差分析法进行参数寻优研究和可靠性分析.结果表明:BASINs/HSPF模型参数寻优的正交极差联合分析模式可大幅减小参数的寻优次数和寻优区间,是获得模型灵敏度参数和参数满意解的高效模式,可为模型参数寻优算法开发提供借鉴;应用正交极差分析的参数率定结果,以青龙河流域下游桃林口水库监测点2011年实测径流数据对模型进行验证,验证期(2011年)的Nash-Sutcliffe效率系数为0.79,稍低于率定期(2012年)的Nash-Sutcliffe效率系数(0.81)以及PEST自动校准的Nash-Sutcliffe效率系数(0.84),水质模拟结果也基本吻合;针对青龙河流域BASINs/HSPF模型,应用正交极差分析方法识别出6个高灵敏的BASINs/HSPF模型参数(IRC、INFILT、AGWRC、DEEPFR、AGWETP和LZSN);应用正交极差分析方法获得的BASINs/HSPF模型参数满意解取值区间依次为:LZSN[2.0,6.3],INFILT[0.084,0.167],AGWRC[0.90,0.95],DEEPFR[0.209,0.333],BASETP[0.067,0.199],AGWETP[0.067,0.199],CEPSC[0.14,0.27],UZSN[1.35,2.00],IRC[0.392,0.483].  相似文献   
43.
A modified chaff jamming recognition method of radar is investigated using grey relational analysis (GRA) based on the difference in echo correlation characteristics between a complex rigid target and chaff cloud in time domain.Slice method (SM),a novel modeling approach,is proposed to construct an electromagnetic scattering model of chaff cloud in a scenario with slowly moving platform that is targeted.The diffusion characteristics and echo characteristics of the chaff cloud are analyzed.The GRA of a real target and chaff cloud shows that the adjacent return waves have a good correlation for the target but a weak correlation for chaff cloud.Since the correlation degree of chaff cloud's echo is far lower than that of a complex rigid target's,the chaff jamming can be identified by setting a reasonable threshold.Simulation results are presented to verify the effectiveness of this method.  相似文献   
44.
Gas-liquid flow in serpentine microchannel with different surface properties exhibits drastically different flow behavior.With water and air as working fluids,the method of numerical simulation was adopted in this paper based on CLSVOF (coupled level set and volume of fluid method) multiphase model.After verifing the reasonability of the model through experiment,by changing wall properties and Re number (Re < 1500),the influences of contact angle and surface roughness on flow regime and Po number were discussed.Moreover,the difference of pressure drop between curve and straight microchannel was also calculated.Beyond that,the combined effect of curve channel and wall properties on flow resistance was analyzed.This paper finds that wall properties have great influence on gasliquid flow in microchannels not only on flow regime but also flow characteristics.Meanwhile,the pressure drop in curve microchannels is larger than straight.It is more beneficial for fluid flowing when the straight part of microchannel is hydrophilic smooth wall and curve part is hydrophobic with large roughness.  相似文献   
45.

Cloud databases provide facilities for large scale data storage and retrieval of distributed data. However, the current access control techniques provided in database systems for maintaining security are not sufficient to secure the private data stored in public cloud databases. In this paper, a new secured data storage algorithm for effective maintenance of confidential data is proposed. To perform storage and retrieval operations of data in the cloud data storage effectively, map reduce algorithms are developed in this work which performs data reduction and fast processing. In order to consider the temporal nature of documents to be retrieved, we propose a new algorithm called Temporal Secured Cloud Map Reduced Algorithm which integrates temporal constraints with map reduce algorithms and also the chaining Hill Cipher encryption algorithms which is proposed newly in this work. The main advantages of the proposed algorithm is that they reduce the processing time and maintains security effectively. The experimental results obtained from this work depict that the proposed model is optimizing cost and it ensures data security.

  相似文献   
46.
随着计算机与人工智能的快速发展,基于图像感知的皮肤病分析方法取得一些成果.然而,以深度学习为主的计算机辅助分析方法依赖于领域专家标注的医学大数据,诊断结果缺乏医学可解释性.为此,文中提出基于视觉的皮肤病分析统一框架——平行皮肤.启发于ACP方法与平行医学图像分析框架,通过构建人工皮肤图像系统实现数据选择与生成,通过预测学习的计算实验完成诊断分析模型构建与评估,并利用描述学习与指示学习融合专家知识,引导人工图像系统数据生成与选择,从而实现闭环诊断分析模型优化.  相似文献   
47.
Cryptococcus curvatus has great potential in fermenting unconditioned hydrolysates of sweet sorghum bagasse. With hydrolysates obtained by enzymatic hydrolysis of the solid pretreated by microwave with lime, the maximal yeast cell dry weight and lipid content were 10.83 g/l and 73.26%, respectively. For hydrolysates obtained in the same way but without lime, these two parameters were 15.50 g/l and 63.98%, respectively. During yeast fermentation, glucose and xylose were consumed simultaneously while cellobiose was released from the residual bagasse. The presence of lime, on one hand, made cellulose more accessible to enzymes as evidenced by higher total reducing sugar release compared to that without during enzymatic hydrolysis step; on the other hand, it caused the degradation of sugars to non-sugar chemicals during pretreatment step. As a result, higher lipid yield of 0.11 g/g bagasse or 0.65 ton/hectare of land was achieved from the pathway of microwave pretreatment and enzymatic hydrolysis while 0.09 g/g bagasse or 0.51 ton/hectare of land was attained from the process of lime-assisted microwave pretreatment followed by the same enzymatic saccharification.  相似文献   
48.
针对GW7B-550型接地开关3个固定螺栓掉落,1个松脱情况,理论仿真计算和模拟试验分析接地开关受力情况,最终确定由接地刀闸导电杆与传动曲臂连接异常、闭锁失效,在大风外力作用下,导电杆逐步抬起,造成单相接地引发故障.  相似文献   
49.
采用顶空-气相色谱法测定食用油中苯和正己烷的残留量。选择顶空进样器的平衡温度和平衡时间分别为120℃和30 min;采用FID检测器,HP-5毛细管柱分离,顶空进样。重点考察了方法的线性、重复性、回收率和仪器的精密度。结果表明:苯和正己烷的线性范围分别为1.26~12.64μg、0.92~9.28μg,线性方程分别为Y=12.453X+11.15(r=0.999 6)、Y=82.56X+59.466(r=0.999 7);苯和正己烷的检出限分别为0.063 0、0.046 4μg/mL,加标回收率分别为96.2%(RSD=1.91%)、93.8%(RSD=1.63%)。该方法灵敏度高,定量准确,具有简单实用的特点,适合食用油中苯和正己烷的残留检测。  相似文献   
50.
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