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1.
Experimental investigation was conducted for the dynamic response of a real spherical explosive chamber that can simulate 200 m deepwater explosive loaded 10 g TNT equivalent. The vibration characteristics and dynamic strength of the chamber were analyzed by measuring the strain profiles of six characteristic points on the chamber. The research results revealed the rule of the dynamic response of the chamber on different ex- plosive loads and static pressures. It provides references for the design and development of the chamber to simu- late deepwater explosion.  相似文献   

2.
The aim of the present study was to investigate the electrophysiological characteristics of the different layers of the olfactory bulb (OB). We used an in vitro OB slice coupled onto a microelectrode array (MEA) for simultaneous detection of spontaneous activities of OB neurons at different sites. Different frequency oscillations dominated the different layers of the OB slice, and the gamma frequency oscillations mainly appeared in the glomerular layer. The waves consisted of negative, positive, and bidirectional spikes, and were distributed at the different layers of the OB slice. Thus, combination of the OB slice with MEA is a useful technique for identifying signal oscillations by multi-site synchronous measurement, and will allow further studies on olfactory information coding and processing function.  相似文献   

3.
Mn1-xZnxFe2O4thin films with various Zn contents and of different thickness were synthesized on glass substrates directly by electroless plating in aqueous solution at 90℃ without heat treatment. The Mn-Zn ferrite films have a single spinel phase structure and well-crystallized columnar grains growing per- pendicularly to the substrates. The results of conversion electron ^57Fe Mossbauer spectroscopy (CEMS) Indicate that the cation distribution of Mn1-xZnxFe204 ferrite nanocrystal thin films fabricated by electroless plating is different from the bulk materials' and a great quantity of Fe^3+ ions are still present on A sites for x〉0.5. When the Zn content of the films increases, Fe^3+ ions in the films transfer from A sites to B sites and the hyperfine magnetic field reduces, suggesting that Zn2. has strong chemical affinity towards the A sites. On the other side, with the increase of the thickness of the films, Fe3+ ions, at B sites in the spinel structure, increase and the array of magnetic moments no longer lies in the thin film plane completely. At x = 0.5, Hc and Ms of Mn1-xZnxFe204thin films show a minimum of 3.7 kA/m and a maximum of 419.6 kA/m, respectively.  相似文献   

4.
Mn1-xZnxFe2O4 thin films with various Zn contents and of different thickness were synthesized on glass substrates directly by electroless plating in aqueous solution at 90℃ without heat treatment.The Mn-Zn ferrite films have a single spinel phase structure and well-crystallized columnar grains growing perpendicularly to the substrates.The results of conversion electron 57Fe M?ssbauer spectroscopy(CEMS)indicate that the cation distribution of Mn1-xZnxFe2O4 ferrite nanocrystal thin films fabricated by electroless plating is different from the bulk materials' and a great quantity of Fe3 ions are still present on A sites for x>0.5.When the Zn content of the films increases,Fe3 ions in the films transfer from A sites to B sites and the hyperfine magnetic field reduces,suggesting that Zn2 has strong chemical affinity towards the A sites.On the other side,with the increase of the thickness of the films,Fe3 ions,at B sites in the spinel structure,increase and the array of magnetic moments no longer lies in the thin film plane completely.At x = 0.5,Hc and Ms of Mn1-xZnxFe2O4 thin films show a minimum of 3.7 kA/m and a maximum of 419.6 kA/m,respectively.  相似文献   

5.
The internal leakage has important influence on low speed performance of continuous rotary electro-hydraulic motors, and research on internal leakage is of important significance to improve the motor low speed performance .UG software is adopted to establish a flow field inside a motor , which ignores the gap between the blade and the blade groove , and a motor fluid model in different working conditions is established .Using ICEM-CFD to generate high-quality O-Net mesh for meeting the computing requirements , the flow field inside the motor is simulated using fluid simulation software CFX.Applying reasonable boundary conditions and then solving it , pressure field distribution and the variation rule of internal leakage with different pressure difference in the flow field are obtained when the clearance value of the motor key components is 0.01mm.At the same time the motor ’ s leakage experiment has also been done to verify the validity of the simulation results , which lays a foundation for the study of motor internal leakage effect on the low speed performance .  相似文献   

6.
Based on archaeological research findings in the Three Gorges region as well as the distribution of prehistoric sites in this area,the following conclusion can be derived:the unique physical and geographical conditions and variations in the Three Gorges region make local people of different ages seek their survival and development in the favorable environment along the riverbanks.Environment evolution has direct impact on the selection of location for survival.The increase of sites quantity reflects the favorable natural environment,but the decrease just reflects the consequence of such natural disasters as flood.  相似文献   

7.
On the basis of static characteristics of free surface of molten pools in laser processing, starting with the change of surface tension, the uniform numerical models are developed for both the liquid and solid regions of metals by applying the enthalpy source method and the porous region model. The flow and heat transfer characteristics in the molten pools and the distribution of surface tension on free surface are disclosed. The shape of free surface is analyzed by considering the static forces on the free surface and by combining with the calculated results of the molten pool. The model is applied to analyzing the laser processing of AISI 304 stainless steel, and the effects of different processing tech nics and material properties on shaping of free surface are discussed.  相似文献   

8.
P systems based multi-objective optimization algorithm   总被引:1,自引:0,他引:1  
Based on P systems, this paper proposes a new multi-objective optimization algorithm (PMOA). Similar to P systems, PMOA has a cell-like structure. The structure is dynamic and its membranes merge and divide at different stages. The key rule of a membrane is the communication rule which is derived from P systems. Mutation rules are important for the algorithm, which has different ranges of mutation in different membranes. The cooperation of the two rules contributes to the diversity of the population, the conquest of the muhimodality of objective function and the convergence of algorithm. Moreover, the unique structure divides the whole population into several sub populations, which decreases the computational complexity. Almost a dozen popular algorithms are compared using several test problems. Simulation results illustrate that the PMOA has the best performance. Its solutions are closer to the true Pareto-optimal front  相似文献   

9.
P systems based multi-objective optimization algorithm   总被引:2,自引:0,他引:2  
Based on P systems, this paper proposes a new multi-objective optimization algorithm (PMOA). Similar to P systems, PMOA has a cell-like structure. The structure is dynamic and its membranes merge and divide at different stages. The key rule of a membrane is the communication rule which is derived from P systems. Mutation rules are important for the algorithm, which has different ranges of mutation in different membranes. The cooperation of the two rules contributes to the diversity of the population, the conquest of the muhimodality of objective function and the convergence of algorithm. Moreover, the unique structure divides the whole population into several sub populations, which decreases the computational complexity. Almost a dozen popular algorithms are compared using several test problems. Simulation results illustrate that the PMOA has the best performance. Its solutions are closer to the true Pareto-optimal front  相似文献   

10.
Based on the corresponding theories of engineering thermodynamics and hydro-dynamics, a careful study is made of the characteristics of air flow in different duct-embedded ways. According to critical Reynolds number, the atmospheric critical velocity of the duct with different diameters, which makes laminar flow different from turbulent flow, is calculated. Given the condition in which a forced flow occurs and the wind strength is larger than the atmospheric pressure gradient along the air-duct, a rational ratio of the length to the diameter is presented. Based on the above theory and field test data on soil temperature and embankment settlement, the advantages and disadvantages are discussed in details of all duct-embedded ways that might affect the stability of embankment.  相似文献   

11.
基于长白山火山区水系长度,对所得到的长白山火山区的卫星图像进行处理,采用多重分形对其水系流域地貌特征进行分析,提取了水系分布的特征参数,根据各项参数刻画流域内部地形的精细结构,突出异常局部的变化趋势,证实了长白山火山区水系流域地貌具有一定的多重分形特征.多重分形可以全面地对地貌形态的总体特征进行定量化描述,所得到的各项参数在研究长白山火山区水系的分布和特征产生积极意义,为进一步研究提供了新的方法和思想.  相似文献   

12.
同步12导联ECG的多重分形分布   总被引:3,自引:2,他引:1  
同步12导联ECG各个导联之间存在着多重分形奇异谱分布.人的ECG多重分形奇异谱面积12导均值由人体神经自律控制,反映的是人体的神经控制强弱,而不是心脏本身的病变程度;心脏本身的生理病理活动对ECG多重分形奇异谱面积12导均值起着一种调制作用.导联的多重分形奇异谱面积分布参量指标可以用来指征冠心病.  相似文献   

13.
为了探索期货市场中的非线性特征,选用大连和芝加哥期货市场中黄豆期货价格时间序列,借助配分函数分布图判定期货时间序列存在多重分形特征,并在此基础上利用多重分形谱对期货时序描述多重分形特征.结果表明,与芝加哥期货市场相比,大连期货市场的多重分形强度更大,风险更大.然后对时间序列进行小波变换,将处理后的时间序列的多重分形强度与原始序列进行比较,发现多重分形特征与时间序列中的噪声及长程相关性有关.  相似文献   

14.
多重分形方法在金属成矿潜力评价中的应用   总被引:4,自引:0,他引:4  
首先探讨了运用多重分形矩方法过程中数据网格化对结果的影响,随后研究了粤北韶关地区4292km2内1448个基岩样品的25项元素的分形分布规律.结果表明,金属地球化学场元素的α-f(α)曲线上凸且连续;地球化学场中元素在空间上的分布具有连续多重分形特征,与成矿密切相关的微量元素一般显示左侧开口明显大于右侧开口,而非主要成矿元素则右侧开口较大;f(α)曲线的形态特征对于判断金属成矿潜力具有一定的指示意义,所提出的非对称指数能很好地反映这一点.  相似文献   

15.
中国云南地区气候变化的多分维分析   总被引:3,自引:0,他引:3  
 利用昆明、丽江、景洪等9个站点1951~2001年的气象观测资料,对中国云南地区的气候变化时间序列进行了多重分维计算与分析,得出了云南地区气候变化的多分维谱特征,对不同海拔高度的丽江、景洪2站的多分维Dq值进行了对比分析,并对结果进行了讨论.  相似文献   

16.
采用基于小波变换模极大值的多重分形分析方法,讨论了大、小时间尺度下的结构函数和多重分形谱的特点。依据实例研究了不同时间下的同质TCP流(W eb)分别在大、小时间尺度下的分形特点;通过对不同协议的同质TCP流的协议本质及拥塞机制的分析,推断其所表现的多重分形谱特点与百分比的相关性;对同一TCP流中不同协议组成的分析,得到TCP总量与分量的多重分形谱特点以及与同质程度的关系。  相似文献   

17.
运用分形分布参数估计、函数盒维数以及多重分形分析等方法对我国沪铜期货价格时间序列进行了实证研究.结果表明,沪铜期货价格不服从正态分布,价格之间存在长记忆性,从而对有效市场假说提出了质疑.函数盒维数及多标度分析的结果揭示了期货价格的聚类特征及标度变化,说明用单一分形模型来描述期货价格是不充分的,多重分形分析方法为更好地描述期货价格的变化规律提供了有力的工具.  相似文献   

18.
常规雷达飞机目标回波的多重分形特性提供了对产生目标回波结构动力学特征的精细描述,为常规雷达飞机目标的分类和识别提供了新的途径.在介绍多重分形的研究方法以及常规雷达飞机目标回波数学模型的基础上,利用多重分形测度分析手段,详细分析常规雷达飞机目标回波的质量指数和多重分形奇异谱等多重分形特性曲线,并定义质量指数对称度Rτ、多重分形谱宽度Δσ和非对称指数Rσ等多重分形特征参数.实验结果表明:喷气式飞机、螺旋桨飞机和直升机这3类飞机目标的常规雷达回波数据具有显著不同的多重分形特征,所定义的3种多重分形特征参数可以作为常规雷达飞机目标分类和识别的有效特征.  相似文献   

19.
分形理论可以洞察隐藏于混沌现象中的精细。本文利用多重分维以及数理统计的方法定量、半定量地描述辽南金伯利岩岩田断裂构造与岩 (矿 )管 (脉 )分布的分维特征及其空间分维关系。从而有效地揭示并证实了各断裂构造在成岩成矿中相应的作用及其重要性 ,对指导找矿具有一定的现实意义  相似文献   

20.
为了理解酗酒对大脑功能的影响,已有研究多数是对被试者的脑电各节律特性分别进行分析,而缺乏分布特性研究.通过3种不同类型的实验,对酗酒者和正常对照组的脑电节律能量的头皮分布进行深入分析.结果表明,在3种不同认知任务下,酗酒者的α节律、δ节律和θ节律在枕区的能量都显著低于正常对照组;而酗酒者脑电β和γ节律在额区与颞区的能量显著高于正常对照组.不同的实验任务对各节律影响也不尽相同.α节律随着任务的不同,能量大小发生变化;枕区的θ节律、额区和颞区的δ节律能量分布在不同任务条件下也各不相同;而β能量则不受实验任务的影响.不同实验类型下酗酒者额区的脑电γ能量有所不同,而正常人却没有显著变化.因此慢波节律在不同区域能量的降低和快波节律在不同脑区能量的增加可能表明酒精长期作用会对大脑造成一定程度的损伤,进而影响大脑的认知过程,而且这种影响还通过皮层电活动头皮分布特性的不同得以体现.  相似文献   

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