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1.
《Ultrasonics》2013,53(1):203-210
Electrical discharge machining (EDM) is a powerful and modern method of machining. In the EDM process, a vapor bubble is generated between the tool and the workpiece in the dielectric liquid due to an electrical discharge. In this process dynamic behavior of the vapor bubble affects machining process. Vibration of the tool surface affects bubble behavior and consequently affects material removal rate (MRR). In this paper, dynamic behavior of the vapor bubble in an ultrasonic assisted EDM process after the appearance of the necking phenomenon is investigated. It is noteworthy that necking phenomenon occurs when the bubble takes the shape of an hour-glass. After the appearance of the necking phenomenon, the vapor bubble splits into two parts and two liquid jets are developed on the boundaries of the upper and lower parts of the vapor bubble. The liquid jet developed on the upper part of the bubble impinges to the tool and the liquid jet developed on the lower part of the bubble impinges to the workpiece. These liquid jets cause evacuation of debris from the gap between the tool and the workpiece and also cause erosion of the workpiece and the tool. Curved tool and workpiece affect the shape and the velocity of the liquid jets during splitting of the vapor bubble. In this paper dynamics of the vapor bubble after its splitting near the curved tool and workpiece is investigated in three cases. In the first case surfaces of the tool and the workpiece are flat, in the second case surfaces of the tool and the workpiece are convex and in the third case surfaces of the tool and workpiece are concave. Numerical results show that in the third case, the velocity of liquid jets which are developed on the boundaries of the upper and lower parts of the vapor bubble after its splitting have the highest magnitude and their shape are broader than the other cases.  相似文献   

2.
蒋国峰  周刚  宋一 《应用声学》2016,24(2):130-132
针对某机载惯导设备在外场的测试需求,设计了以PC-104为显示、控制和数据处理核心,并扩展程控数字表、多通道矩阵板,构建了原位测试仪的硬件电路。根据系统的功能要求和硬件电路特性,利用LabWindows/CVI虚拟仪器平台编制了人机接口界面和测试程序,控制硬件电路对某惯导设备的静态电阻和在线电压进行测试,并接收、分析、处理惯导原位工作时输出的实时串行数据,完成对惯导设备的静态测试和动态性能监测,实现对某机载惯导设备原位测试过程的自动化和测试结果管理的智能化,提高了测试效率和测试精度。该仪器通过改变或控制测试仪器的类别,可实现对多路信号多种性能指标的测试。应用结果表明,该测试仪具有性能稳定、操作简便、应用领域广、通用性强等特点。  相似文献   

3.
本文以解析GPS的时间信息和位置信息为目标,通过使用嵌入式GPS模块和AVR控制器,设计和制作GPS授时与定位装置,实现时间信息和位置信息的解析和显示等问题。本文首先给出了基于GPS模块和AVR控制器的授时与定位装置的整体构架,然后对各个部分的 硬件进行详细设计,给出了硬件设计电路和软件设计框图。最后对所设计的基于GPS模块和AVR控制器的授时与定位装置进行实物制作,证明了设计内容的正确性和可行性,具有一定的实际应用价值。  相似文献   

4.
为解决近红外光谱法分析物质浓度过程中缺乏可测度分析而导致测量过程存在一定盲目性问题,研究在已知测量条件、样品种类、被测组分以及建模分析方法的条件下,利用近红外光谱谱线特性作为参数,在大量样品近红外光谱采集和标准法测得浓度数据等工作前,对被测物质浓度的分析误差做大致估算。经过大量尝试和试验提出等效信噪比(ESNR)和谱线重叠系数(OC)两个重要参数,其中ESNR反映待测组分吸光度占总吸光度的比重,而OC则反映待测组分近红外光谱曲线间的重叠程度。通过理论仿真得到光谱分析中用经典的偏最小二乘回归建立定量分析模型时谱线特性与物质浓度分析误差的关系,分别计算ESNR和OC与被测组分浓度分析误差(RMSE)的关系,并且研究两个谱线参数的独立性。利用理论分析得到结果对浓度为8%~12%乙醇水溶液进行可测度分析,并与近红外光谱法分析的实际结果进行比较。研究通过理论仿真得到使用光谱分析中经典的偏最小二乘回归建立定量分析模型时谱线特性与物质浓度分析误差的关系,其中ESNR与RMSE成反比关系,而OC与被测组分分析误差成非线性的单调关系,并且验证了ESNR和OC两个参数的独立性。通过理论计算和乙醇水溶液近红外光谱检测实验对等效信噪比和谱线重叠系数与光谱分析浓度误差的定量关系进行讨论,通过理论分析得到的乙醇浓度RMSE预估值为0.30%,近红外光谱分析实际RMSE为0.32%,相对误差6.67%,二者结果相符。实现了在测量条件、样品种类、被测组分以及建模分析方法已知的条件下基于近红外光谱分析的待测组分含量理论误差的定量计算和实验验证。该研究明确了对近红外光谱法分析物质浓度有明确定量关系的两个谱线参数,给出了使用光谱分析中经典的偏最小二乘回归建立定量分析模型时的分析误差经验曲线,以及利用曲线进行近红外光谱法待测组分浓度可测度分析方法。结果表明所提出的ESNR和OC两个谱线特性参数的有效性,以及分析误差预估方法的有效性。为近红外光谱法待测组分浓度定量分析提供了有效、快捷的预估方法,完善了近红外光谱法成分含量可测度分析理论,对近红外光谱法物质浓度定量分析研究具有一定指导意义。  相似文献   

5.
Ultrasonic evaluation of the physical and mechanical properties of granites   总被引:3,自引:0,他引:3  
Masonry is the oldest building material that survived until today, being used all over the world and being present in the most impressive historical structures as an evidence of spirit of enterprise of ancient cultures. Conservation, rehabilitation and strengthening of the built heritage and protection of human lives are clear demands of modern societies. In this process, the use of nondestructive methods has become much common in the diagnosis of structural integrity of masonry elements.With respect to the evaluation of the stone condition, the ultrasonic pulse velocity is a simple and economical tool. Thus, the central issue of the present paper concerns the evaluation of the suitability of the ultrasonic pulse velocity method for describing the mechanical and physical properties of granites (range size between 0.1-4.0 mm and 0.3-16.5 mm) and for the assessment of its weathering state. The mechanical properties encompass the compressive and tensile strength and modulus of elasticity, and the physical properties include the density and porosity. For this purpose, measurements of the longitudinal ultrasonic pulse velocity with distinct natural frequency of the transducers were carried out on specimens with different size and shape. A discussion of the factors that induce variations on the ultrasonic velocity is also provided.Additionally, statistical correlations between ultrasonic pulse velocity and mechanical and physical properties of granites are presented and discussed. The major output of the work is the confirmation that ultrasonic pulse velocity can be effectively used as a simple and economical nondestructive method for a preliminary prediction of mechanical and physical properties, as well as a tool for the assessment of the weathering changes of granites that occur during the serviceable life. This is of much interest due to the usual difficulties in removing specimens for mechanical characterization.  相似文献   

6.
素有“液体黄金”之称的橄榄油已成为健康食用油的代名词,不仅身价陡增,而且在非产地市场也已成为一种畅销油。在橄榄油检测技术中光谱法与其他技术相比具有快速、无损、无样品处理等优势而备受关注,而不同的光谱检测方法在检测的物质成分上各有侧重,例如红外光谱法侧重于脂肪酸含量的检测、拉曼光谱法侧重于分子的检测、荧光光谱法侧重于光敏物质的检测以及吸收光谱法侧重于光敏物质和不饱和脂肪酸的检测等。荧光及吸收光谱对光敏物质反应极其灵敏,而橄榄油富含叶绿素等光敏物质,因此荧光及吸收光谱成为一种鉴别橄榄油的有效技术手段。叶绿素是一种含有环卟啉结构的有机分子,该类分子结构具有吸光特性,且不同的叶绿素吸收光谱各异,其中绿色植物的叶绿素a含量最多。为深入研究叶绿素的吸收光谱及荧光特性在橄榄油鉴别中的应用,将特级初榨橄榄油中掺入不同比例的玉米油,已达到间接调控橄榄油中叶绿素含量的目的,测量不同掺伪比例橄榄油的荧光及吸收光谱并研究与叶绿素浓度的相关性,以此来研究叶绿素浓度与掺伪量对橄榄油吸收光谱及荧光特性的影响。取10份同批次的特级初榨橄榄油,将其中9份按照等比例稀释,并对10份样品按照掺伪量依次排序;依次采集这10份样品的荧光及吸收光谱,比较叶绿素浓度与掺伪量的相关性及对这两种光谱技术在橄榄油鉴别中的影响。随着叶绿素浓度的上升,荧光强度由弱变强,并在某一时刻后会出现荧光强度急剧减弱的现象,即聚集荧光猝灭。这种现象主要是由于叶绿素的环卟啉分子结构引起的分子间π-π作用,使未被激发的低能分子与高能分子堆叠在一起,能量的辐射跃迁(荧光)也转变为分子间的能量转移(热能交换)。对于吸收光谱,随着叶绿素浓度的上升,吸收光谱的强度也逐渐增强。橄榄油中叶绿素吸收的能量主要去向包括镁电子辐射跃迁产生荧光以及分子间热能交换两部分,而橄榄油的吸收光谱并未出现类似于聚集荧光猝灭的现象,且吸收光谱强度与掺伪浓度间存在近似线性相关的关系。结果表明:当聚集荧光猝灭出现时,叶绿素吸收的能量仍然与浓度呈线性相关,此时高、低能分子堆叠引起的热能交换效率提高。  相似文献   

7.
与地理环境相关的中国铁路客运网拓扑结构   总被引:1,自引:0,他引:1       下载免费PDF全文
谭江峡  王杜鹃  王鑫  王茹  蔡勖 《物理学报》2008,57(11):6771-6776
以中国铁路车站作为“节点”,每辆列车经过的相邻两个停靠车站之间连接一条“边”,构成有方向有权重的中国铁路客运网.首先研究了该网络的拓扑结构,包括连接度、聚集系数、最短路径和强度,结果表明中国铁路客运网的连接度分布,强度分布都是介于指数分布和幂率分布之间,是一个具有小世界性质的阶层网络.修建铁路需考虑人口分布,行政区域等因素.铁路固定设施成本高,修建完成后很难做变动,因此需考虑诸多空间地理环境对中国铁路客运网的影响,如站点的连接度和站点的相连站点之间的平均行驶距离之间的关系、车站的分布密度与人口密度的关系, 关键词: 铁路客运网 拓扑统计 小世界 地理环境  相似文献   

8.
多层石墨烯具有超宽的光谱吸收范围及独特的光电性能,是制作下一代光电探测器件的理想材料。以石墨烯的带间隧穿理论为基础,提出了一个多层石墨烯纳米带结构的光电探测器模型,纳米带的两端与源极和漏极相连,夹在半导体基质和上下栅极之间。利用这个模型,建立了多层石墨烯纳米带探测器的光电转换机制,讨论了上栅极电压不同时探测器的工作原理,研究了源-漏极间光电流及暗电流与入射光能量的关系,探讨了探测器的偏置电压,耗尽层长度以及带隙取值对暗电流的影响,并分析了不同参数下探测器响应率以及探测率随入射光能量的变化关系。结果表明,探测器的响应率随纳米带层数的增加而增加,受带隙,耗尽层长度和偏置电压的影响,最大的响应率约为103 A·W-1; 通过限制上栅压,带隙等变量可以控制系统暗电流,增大探测器的探测率,最高探测率约为109 cm·Hz1/2·W-1。多层石墨烯纳米带结构可以增强探测器对入射光的吸收,提高探测器的灵敏度以及对弱光的探测能力,实现对太赫兹到远红外波段入射光的有效探测,探测性能远高于许多量子结构和窄带半导体结构的光电探测器。  相似文献   

9.
Histological and histochemical analyses were carried out in order to evaluate the influence of the topical application of a synthetic juvenile hormone on the secretory cycle and degeneration of the venom gland of Apis mellifera. Newly emerged workers received the topical application of synthetic hormone and the results were compared to the normal development of the secretory cycle in virgin and mated queens. The first worker group received the juvenile hormone diluted in hexane (2 microg/microL), the second received only 1 microL of hexane, and the third did not receive any kind of application. After the application the workers were returned to the colony and collected at the ages of 14 and 25 days of adult life. The groups with virgin queens and the other with mated queens, did not receive the treatment. The results show that the individuals treated with juvenile hormone and with pure hexane presented differences in the histological and cytochemical aspects of the secretory cells of the venom gland. The data indicate that both the juvenile hormone and hexane accelerate the activity of the secretory cycle and the degeneration of the venom gland; however, the juvenile hormone proved to be more effective than hexane.  相似文献   

10.
大功率盘形激光焊飞溅特征分析   总被引:2,自引:0,他引:2       下载免费PDF全文
焊接过程的在线监控是保证激光焊接质量的关键, 为此, 首先要找到焊接过程传感特征量变化规律以及与焊缝质量间的关系. 飞溅是大功率盘型激光焊接过程中的一个重要现象, 其特征与焊接质量、焊接过程稳定性以及能量利用率等有着密切的联系. 以大功率盘形激光焊接304不锈钢为试验对象, 研究焊接过程中的飞溅特征. 在紫外波段和可见光波段应用高速摄像机摄取焊接过程中产生飞溅的瞬态特征, 通过计算机图像处理技术分析飞溅的数量、面积、行程和质心高度特征参量. 以焊件熔宽作为衡量焊接质量与焊接过程稳定性的因素, 对飞溅特征量进行线性和高次拟合, 研究飞溅特征参量的波动规律, 并与焊件熔宽的变化对比, 探索焊接过程的飞溅特征参量变化规律. 试验结果表明, 根据飞溅特征量变化规律能够对大功率盘形激光焊接304不锈钢板焊接质量做出动态评估, 为实现焊接质量的在线监控提供了试验依据.  相似文献   

11.
土壤pH值是影响土壤养分转化和土壤肥力的关键因素,使用近红外光谱技术对土壤pH值进行检测可为土壤资源的开发利用提供重要依据。卷积神经网络作为深度学习在人工智能方面的典型算法,由于其结构具备“局部感知,权值共享”的能力,因此不仅能够对复杂的光谱数据进行特征抽取,还能够减少网络的训练参数,提高网络的运算效率。将卷积神经网络用于近红外光谱的建模分析,并提出一种基于一维卷积的卷积神经网络和近红外光谱的土壤pH值预测方法。网络由Python语言调用Tensorflow工具包搭建而成,其结构由输入层、卷积层、池化层以及全连接层四部分组成。以欧洲统计局在2008年-2012年开展的土地利用及覆盖面积统计调查所收集的矿物质土壤光谱样本数据集为研究对象,为消除光谱中存在的基线漂移,提高信噪比,对原始可见光近红外光谱(400~2 500 nm)进行一阶导数和Savitzky-Golay平滑处理。在模型训练过程中,随机选取15 000个样本作为训练集,剩余的2 272个样本作为测试集,探讨不同的卷积层个数及训练迭代次数对模型性能的影响,并采用ReLU激活函数及Adam优化器防止模型出现梯度消失现象,提高模型的稳定性,之后通过分析模型的拟合优度和运算成本确定模型的最佳性能,最后将网络模型与传统的BP和PLSR模型进行对比。结果显示,当模型迭代次数为2 500次,卷积层个数为4层时,模型达到最佳状态,模型对训练集的均方误差从1.898降到了0.097;模型对测试集的拟合优度为0.909,分别比BP和PLSR模型高0.117和0.218。使用卷积神经网络可以对土壤近红外光谱的内部特征信息进行抽取,从而实现对大面积土壤pH值的高效准确预测。CNNR模型可对农作物的合理栽种及精准施肥提供指导,从而达到土壤结构稳定和可持续发展的目的。基于卷积神经网络的近红外光谱回归方法也可以推广到其他土壤信息研究。  相似文献   

12.
13.
A comprehensive review is given about the enormous versatility of photoelectron spectroscopy to study the especially complex interaction of oxygen with metal surfaces and the nature of the reaction products. The great variety of well definable parameters of a photoemission experiment, e.g. energy, direction of incidence and polarization of the primary photon beam as well as the detection direction of the photocurrent, yields - through the distributions of energy, momentum and spin polarization of the photoelectrons - detailed insight in the kinetic, thermodynamic, electronic and structural aspects of oxygen adsorption on metal surfaces and incipient oxidation. Characteristic electron binding energies, multiplet and satellite structures of both the oxygen and substrate emission allow a distinction between possible states of adsorbed oxygen, i.e. condensed, molecularly and atomically adsorbed, and incorporated oxygen. Even a distinction between octahedral and tetrahedral oxygen coordination of oxide cations may be possible. Analysis of peak intensities (as a measure of coverages and concentrations) as a function of time and temperature provides information about the kinetics and thermodynamics of adsorbed layer and oxide formation. Angular resolved photoemission studies have led to the determination of absolute adsorption site geometries, individual ad-orbital symmetries and two-dimensional band structure formation within the oxygen overlayer. Measurement of the photoelectron spin-polarization offers a method to study surface magnetism, e.g. of ferromagnetic oxides. The determination of local work functions through the photoemission behavior of co-adsorbed rare gas atoms establishes a uniquely important tool to characterize heterogenous surfaces, e.g. oxygenated surfaces with coexisting oxygen states. Numerous different oxygen/metal systems are chosen to demonstrate the state of the art. Results from other surface spectroscopies and theoretical model calculations are, of course, considered and still open problems are named, e.g. the ionicity of the oxygen chemisorption bond. Problems inherent in sputter profiling through surface oxides as observed with photoemission are briefly addressed. This work is rounded by a list of about 600 references in alphabetic order of the reacting metals.  相似文献   

14.
岳松  高冬平  张兆传  王韦龙 《中国物理 B》2016,25(11):118403-118403
The frequency characteristics of free oscillation magnetron(FOM) and injection-locked magnetron(ILM) are theoretically investigated.By using the equal power voltage obtained from the experiment data,expressions of the frequency and radio frequency(RF) voltage of FOM and ILM,as well as the locking bandwidth,on the anode voltage and magnetic field are derived.With the increase of the anode voltage and the decrease of the magnetic field,the power and its growth rate increase,while the frequency increases and its growth rate decreases.The theoretical frequency and power of FOM agree with the particle-in-cell(PIC) simulation results.Besides,the theoretical trends of the power and frequency with the anode voltage and magnetic field are consistent with the experimental results,which verifies the accuracy of the theory.The theory provides a novel calculation method of frequency characteristics.It can approximately analyze the power and frequency of both FOM and ILM,which promotes the industrial applications of magnetron and microwave energy.  相似文献   

15.
In this paper, we present the elementary principles of nonlinear quantum mechanics (NLQM), which is based on some problems in quantum mechanics. We investigate in detail the motion laws and some main properties of microscopic particles in nonlinear quantum systems using these elementary principles. Concretely speaking, we study in this paper the wave-particle duality of the solution of the nonlinear Schr?dinger equation, the stability of microscopic particles described by NLQM, invariances and conservation laws of motion of particles, the Hamiltonian principle of particle motion and corresponding Lagrangian and Hamilton equations, the classical rule of microscopic particle motion, the mechanism and rules of particle collision, the features of reflection and the transmission of particles at interfaces, and the uncertainty relation of particle motion as well as the eigenvalue and eigenequations of particles, and so on. We obtained the invariance and conservation laws of mass, energy and momentum and angular momentum for the microscopic particles, which are also some elementary and universal laws of matter in the NLQM and give further the methods and ways of solving the above questions. We also find that the laws of motion of microscopic particles in such a case are completely different from that in the linear quantum mechanics (LQM). They have a lot of new properties; for example, the particles possess the real wave-corpuscle duality, obey the classical rule of motion and conservation laws of energy, momentum and mass, satisfy minimum uncertainty relation, can be localized due to the nonlinear interaction, and its position and momentum can also be determined, etc. From these studies, we see clearly that rules and features of microscopic particle motion in NLQM is different from that in LQM. Therefore, the NLQM is a new physical theory, and a necessary result of the development of quantum mechanics and has a correct representation of describing microscopic particles in nonlinear systems, which can solve problems disputed for about a century by scientists in the LQM field. Hence, the NLQM built is very necessary and correct. The NLQM established can promote the development of physics and can enhance and raise the knowledge and recognition levels to the essences of microscopic matter. We can predict that nonlinear quantum mechanics has extensive applications in physics, chemistry, biology and polymers, etc.   相似文献   

16.
In this paper, we present the elementary principles of nonlinear quantum mechanics (NLQM), which is based on some problems in quantum mechanics. We investigate in detail the motion laws and some main properties of microscopic particles in nonlinear quantum systems using these elementary principles. Concretely speaking, we study in this paper the wave-particle duality of the solution of the nonlinear Schrödinger equation, the stability of microscopic particles described by NLQM, invariances and conservation laws of motion of particles, the Hamiltonian principle of particle motion and corresponding Lagrangian and Hamilton equations, the classical rule of microscopic particle motion, the mechanism and rules of particle collision, the features of reflection and the transmission of particles at interfaces, and the uncertainty relation of particle motion as well as the eigenvalue and eigenequations of particles, and so on. We obtained the invariance and conservation laws of mass, energy and momentum and angular momentum for the microscopic particles, which are also some elementary and universal laws of matter in the NLQM and give further the methods and ways of solving the above questions. We also find that the laws of motion of microscopic particles in such a case are completely different from that in the linear quantum mechanics (LQM). They have a lot of new properties; for example, the particles possess the real wave-corpuscle duality, obey the classical rule of motion and conservation laws of energy,momentum and mass, satisfy minimum uncertainty relation, can be localized due to the nonlinear interaction, and its position and momentum can also be determined, etc. From these studies, we see clearly that rules and features of microscopic particle motion in NLQM is different from that in LQM. Therefore, the NLQM is a new physical theory, and a necessary result of the development of quantum mechanics and has a correct representation of describing microscopic particles in nonlinear systems, which can solve problems disputed for about a century by scientists in the LQM field. Hence, the NLQM built is very necessary and correct. The NLQM established can promote the development of physics and can enhance and raise the knowledge and recognition levels to the essences of microscopic matter. We can predict that nonlinear quantum mechanics has extensive applications in physics, chemistry, biology and polymers, etc.  相似文献   

17.
We explore the intimate connection between spacetime geometry and electrodynamics. This link is already implicit in the constitutive relations between the field strengths and excitations, which are an essential part of the axiomatic structure of electromagnetism, clearly formulated via integration theory and differential forms. We review the foundations of classical electromagnetism based on charge and magnetic flux conservation, the Lorentz force and the constitutive relations. These relations introduce the conformal part of the metric and allow the study of electrodynamics for specific spacetime geometries. At the foundational level, we discuss the possibility of generalizing the vacuum constitutive relations, by relaxing the fixed conditions of homogeneity and isotropy, and by assuming that the symmetry properties of the electro-vacuum follow the spacetime isometries. The implications of this extension are briefly discussed in the context of the intimate connection between electromagnetism and the geometry (and causal structure) of spacetime.  相似文献   

18.
The effects of the concentration and complex index of refraction of hydrosols on the flux of solar radiation in the atmosphere and ocean have been studied by solving the equation of radiative transfer in model atmosphere-ocean systems. Scattering and absorption by aerosols, hydrosols, air and water molecules, as well as reflection and refraction at the ocean surface, are taken into account by applying the matrix method to the combined atmosphere-ocean system. Nine values of the index of refraction and four values of the concentration are assumed for the hydrosols. The flux of the solar radiation at the top of the atmosphere, just above and below the ocean surface, and at several depths in the ocean is calculated in the spectral interval between 0.3 and 0.8 μm. The flux of solar radiation in the atmosphere and ocean is significantly affected by the oceanic turbidity, as well as by the complex index of refraction of hydrosols.  相似文献   

19.
本文基于Hill动力学与Michaelis-Menten方程,建立理论模型研究两细胞间基因、蛋白耦合振荡中的噪声效应.研究发现,在Notch信号通路中,两细胞间基因、蛋白耦合振荡呈现了周期振荡特性,表明了细胞间信号传导的同步振荡特性.“内在”噪声和“外在”噪声对两细胞间基因、蛋白耦合振荡有着不同的作用.内噪声有利于细胞间Notch信号通路中各基因、蛋白表达再次提升.外噪声诱导通路中基因、蛋白的表达水平降低,周期振荡变得阻尼.内、外噪声共同作用不仅可使得基因表达适当并呈现出持续振荡模式,而且还可使得细胞间基因转录合成相应的蛋白过程呈现出持续振荡模式.从而表明了基因表达的内、外噪声共同作用有利于控制细胞间基因激活、蛋白合成保持周期节律性.本文理论结果揭示了内外噪声对细胞间Notch信号通路动力学的一种调控机制,确定了内外噪声各自的调控效应,澄清了内外噪声共同作用调控体系持续周期振荡的物理机制,理论结果符合实验,可为设计阻止Notch体系基因、蛋白变异导致的多种疾病和癌症的通路治疗方案提供理论依据.  相似文献   

20.
 分析了颗粒介质在冲击载荷下的加载、卸载本构关系,应用特征线理论对平面一维爆炸冲击波在颗粒介质中的衰减进行了计算。结果表明:组成颗粒的材料、孔隙率及炸药的爆速决定了初始冲击波峰值的大小。炸药爆速越高,介质孔隙率越大,材料本身的冲击阻抗越大,初始压力越高。炸药长度、材料本身的冲击阻抗及介质的孔隙率决定了冲击波的衰减速度。炸药长度越小,材料本身的冲击阻抗越大,介质的孔隙率越高,冲击波衰减越快。  相似文献   

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