排序方式: 共有29条查询结果,搜索用时 15 毫秒
11.
在保证有充足氧气的前提下 ,按正交设计 ,研究水质氨态氮浓度、pH值、盐度和温度四种环境因子 ,对实验感染暴发性流行病病原的中国对虾发病的影响。在感染的不同时期 ,这四种环境因子对带毒对虾死亡率的影响程度不同。感染后 3~ 4天 ,影响程度从大到小的次序为盐度、pH值、温度、氨态氮浓度 ,感染后 5天 ,影响程度从大到小的次序变为氨态氮浓度、pH值、温度、盐度。我们还进行了混合水平的正交实验 ,即在盐度水平不变 ,氨态氮浓度降到适宜的水平 ,再研究温度、pH值、氨态氮三种因子对带毒对虾的影响 ,结果表明 :三种环境因子的影响程度由大到小的次序为温度、氨态氮浓度和pH值 ,这与我国养殖对虾发病时间从南到北推移的现象相符合。还对环境因子与发病率和死亡率的关系进行了探讨 相似文献
12.
An indoor experiment on explosive compaction of saturated sand has been done.The changes of pore water pressure during blasting are measured and the laws of pore water pressure increment and dissipation are analyzed.It indicates that the processes of increment and dissipation of pore water pressure have particularity along the depth and radial.At the same time,the development rule of liquefaction under explosive loading is also analyzed;these conclusions obtained in the experiment,may provide some useful references for the engineering design and the theoretic study of explosive compaction for water-saturated granular foundation. 相似文献
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The detecting method for low concentration of TNR by derivative polarography was proposed. Quantitative detection was carried out at selected polargraphic peaks,-0.5 V and -0.75 V. The relative standard curve, linear range and detection limit were obtained. Meanwhile, interference and recovery experiments were also studied and experimental conditions were optimum. The results show that this method have a wide linear range and lower detection limit. 相似文献
15.
在一类m元离散时滞差分方程神经网络模型中引入了具有明显实际意义的非线性不连续信号传输函数,并利用离散系统的解半环分析这一强有力工具,通过引入一个辅助系统,证明了该模型的每个解或者是最终周期的或者是无界的这一有趣的动力学性质 相似文献
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H. J. Duncan 《Potato Research》1999,42(1):25-29
Summary An appraisal was undertaken of the key factors involved in explosion and combustion processes mainly associated with the fogging
of chlorpropham formulations into potato stores. The key factors considered are source of ignition, solvents, explosive limits
of solvents, the presence and atmospheric concentrations of particulate clouds and the role of particulate material in dust
explosions. Also the sequence of events that takes place in a dust explosion, including critical concentrations of dust required
to initiate the reactions involved and the particular relevance of the above events to the behaviour of chlorpropham fogs
both at the time of application and when distributed throughout a store. The relevance of fine dust already present in the
store to the initiation of explosions, particularly secondary explosions, which are considered to be a major cause of concern
due to their severity, is also emphasised. 相似文献
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炸药与产物的状态方程、反应速率方程和混合法则构成描述固体炸药起爆和爆轰过程的本构方程.由于反应速率方程和状态方程都有多种形式,而且都有独立的标定方式,它们通过一个假定的混合法则联系起来,其相容性没有确认.用这样一组方程去描述炸药起爆起和爆轰时反应区中高温、高压和高速的化学非平衡状态,其有效性也没有保证.本文提出了一种利用拉格朗日实验及其分析方法来确定上述本构方程相容性的方法.文中标定了三种TNT炸药的本构方程.将标定的本构方程用于一维数值模拟计算中,较好地模拟了这些炸药的拉格朗日实验结果和楔形实验结果. 相似文献
18.
在1994年山东地区对虾暴发性流行病研究中,在未检出杆状病毒的中国对虾样品中首次发现1种球形病毒,电镜下观察到该病毒外有囊膜,直径200nm左右,在细胞质中形成球形包涵体,以宿主肝胰腺和心脏为主要靶器官;受其感染的肝胰腺细胞的细胞器出现一系列病理变化:线粒体从增生、肿胀、内嵴溶解到出现纤维化,最后崩解;糙面内质网也明显增生、脱颗粒、排列紊乱,严重感染时,肿胀成泡状,甚至分解;细胞核出现病变较晚且较轻。人工感染实验证明该病毒可引起中国对虾暴发性流行病的症状,13d累积死亡率可达90%。 相似文献
19.
A numerical simulation test of the internal explosive loading on large space structure was carried out by employing algorithm ANSYS/LS DYNA.An appropriate model was established for calculating the dynamic responses of the large space cylindrical reticulated shell under inner blast loading based on the proof of correctness and reliability of the model and parameters selection.Combining the Ritz vibration mode superposition method with the Proper Orthogonal Decomposition (POD) method, the problems of spatiotemporal asynchrony of shock waveforms and pressure distributions on large space structure surface were solved and the calculation for dynamic response of large space structure was reduced and simplified.Furthermore, the numerical simulation of dynamic responses was carried out.And the influence of the ratio of rise to span and the explosive position on the dynamic responses of the structure was studied.It was found that the calculation model was suitable for the dynamic response analysis of the large space cylindrical reticulated shell under internal explosion and the cylindrical reticulated shells with bigger ratios of rise to span were stronger in the capacity of anti explosion.In general, the damages to the large space structure caused by eccentric blast shock waves were more serious than that caused by central explosion.And it was the most disadvantageous to the edge components of the structure.The more attention should be paid to the anti explosion capacity of the support areas and the edge components while designing the shells. 相似文献
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利用Lagrange实验结果和改进的Lagrange分析方法,对固体炸药在动高压流场中的本构方程进行了整体标定.未反应炸药和已反应产物都采用JWL状态方程.分析得到了每个Lagrange位置上的压力p,质量速度u,比容v,比内能随e时间的变化过程,同时可标定基于JWL状态方程的固体炸药的点火与增长型反应速率方程.标定的JWL状态方程和点火与增长型反应速率方程具有良好的相容性,参数可以直接用于动力学计算程序LS-DYNA3D.本文对铸装TNT炸药的二维起爆过程进行了计算. 相似文献