Dynamic Analysis of Hydrodynamic Behavior of A Flatfish Cage System Under Wave Conditions

This paper presents a simulation model based on the finite element method. The method is used to analyze the motion response and mooring line tension of the flatfish cage system in waves. The cage system consists of top frames, netting, mooring lines, bottom frames, and floats. A series of scaled physical model tests in regular waves are conducted to verify the numerical model. The comparison results show that the simulated and the experimental results agree well under the wave conditions, and the maximum pitch of the bottom frame with two orientations is about 12o. The motion process of the whole cage system in the wave can be described with the computer visualized technology. Then, the mooring line tensions and the motion of the bottom frame with three kinds of weight are calculated under different wave conditions. According to the numerical results, the differences in mooring line tensions of flatfish cages with three weight modes are indistinct. The maximum pitch of the bottom frame decreases with the increase of the bottom weight.

Propagation behavior of acoustic wave in wood

We used acoustic tests on a quarter-sawn poplar timbers to study the effects of wood anisotropy and cavity defects on acoustic wave velocity and travel path, and we investigated acoustic wave propagation behavior in wood. The timber specimens were first tested in unmodified condition and then tested after introduction of cavity defects of varying sizes to quantify the transmitting time of acoustic waves in laboratory conditions. Two-dimensional acoustic wave contour maps on the radial section of specimens were then simulated and analyzed based on the experimental data. We tested the relationship between wood grain and acoustic wave velocity as waves passed in various directions through wood. Wood anisotropy has significant effects on both velocity and travel path of acoustic waves, and the velocity of waves passing longitudinally through timbers exceeded the radial velocity. Moreover, cavity defects altered acoustic wave time contours on radial sections of timbers. Acous-tic wave transits from an excitation point to the region behind a cavity in defective wood more slowly than in intact wood.

Nonlinear Dynamic Behavior of Moored Buoy Excited by Free Surface Waves

In this paper, studied are the dynamics of a moored buoy near the surface subjected to wave excitation. According to the physical structure, submersible buoy moored by tethered line is modeled firstly. Then from the differential equations, the natural frequencies are estimated by neglecting the coupling between tangential and normal direction. By use of numerical integration method, solutions are obtained. On this basis, strange attractors and bifurcation phenomena are obtained by applying Poineare map, phase plots and bifurcation diagram, showing the existence of the chaotic response in this system when wave steepness is high enough.

Dynamical behaviors of traveling wave solutions to a Fujimoto-Watanabe equation

We study dynamical behaviors of traveling wave solutions to a Fujimoto-Watanabe equation using the method of dynamical systems. We obtain all possible bifurcations of phase portraits of the system in different regions of the threedimensional parameter space. Then we show the required conditions to guarantee the existence of traveling wave solutions including solitary wave solutions, periodic wave solutions, kink-like（antikink-like） wave solutions, and compactons. Moreover, we present exact expressions and simulations of these traveling wave solutions. The dynamical behaviors of these new traveling wave solutions will greatly enrich the previews results and further help us understand the physical structures and analyze the propagation of nonlinear waves.

Edge Plasma behavior during Improved Confinement by Lower Hybrid Wave Heating in HT-6M Tokamak

Lower hybrid heating (LHH) has been successfully carried out in the HT-6M toka-mak. The H-mode has been obtained with a power threshold of 50 kW under a boronized wall condition. Both energy and particle confinements have been improved along with a dropped edge plasma density and an increase electron temperature during the LHH phase. A negative Er well plays a key role of triggering and sustaining the good confinement. Both electrostatic fluctuation of the plasma potential and the density fluctuations dropped to an ultra-low level. The observation of an enhanced Er shear before the reduction in turbulence level is consistent with an increased Er shear as the cause of turbulence suppression.

WAVE PROPAGATION IN PIEZOELECTRIC/PIEZOMAGNETIC LAYERED PERIODIC COMPOSITES

This paper is concerned with the dynamic behaviors of wave propagation in layered periodic composites consisting of piezoelectric and piezomagnetic phases. The dispersion relations of Lamb waves axe derived. Dispersion curves and displacement fields are calculated with different piezoelectric volume fractions. Numerical results for BaTiO3/CoFe2O4 composites show that the dispersion curves resemble the symmetric Lamb waves in a plate. Exchange between the longitudinal （i.e. thickness） mode and coupled mode takes place at the crossover point between dispersion curves of the first two branches. With the increase of BaTiO3 volume fraction, the crossover point appears at a lower wave number and wave velocity is higher. These findings are useful for magnetoelectric transducer applications.

CONSTRUCTION AND QUALITATIVE BEHAVIOR OF SOLUTIONS FOR A MODEL EQUATION FOR FLUID FLOW IN A PIPE

This paper investigates the following model equation:where A>0 and p'(v)<0.It proves that the equation admits a unique global discontinuous solution on in a class of piecewise continuous and piecewise smooth drictiom with a backward rarefaction wave and a forward shock wave under certain conditions.

EXPONENTIAL ATTRACTOR FOR THE GENERALIZED SYMMETRIC REGULARIZED LONG WAVE EQUATION WITH DAMPING TERM

The global fast dynamics for the generalized symmetric regularized long wave equation with damping term is considered. The squeezing property of the nonlinear semi_group associated with this equation and the existence of exponential attractor are proved. The upper bounds of its fractal dimension are also estimated.

LARGE TIME BEHAVIOR OF SOLUTIONS TO1-DIMENSIONAL BIPOLAR QUANTUM HYDRODYNAMIC MODEL FOR SEMICONDUCTORS

In this article, we study the 1-dimensional bipolar quantum hydrodynamic model for semiconductors in the form of Euler-Poisson equations, which contains dispersive terms with third order derivations. We deal with this kind of model in one dimensional case for general perturbations by constructing some correction functions to delete the gaps between the original solutions and the diffusion waves in L2-space, and by using a key inequality we prove the stability of diffusion waves. As the same time, the convergence rates are also obtained.

Study of the Voltammetric Behavior of Heme and Its Direct Analysis Application

The electroanalytical method of ferriheme was studied by linear sweep voltammetry in medium of 0.05 mol/L Tris+0.05 mol/L NH3?NH4Cl buffer at hang mercury drop electrodes (HMDE). Heme exhibits two pair reversible redox peaks and one irreversible peak. The cathodic peak potentials are?;0.236 V, ?0.422 V and ?1.408 V respectively. The first and the third peaks can be used for directly quantitative determination of heme concentrations. The peak currents are good linear relationship with heme concentration in ranges of 3×10?6–6×10?5 mol/L and 3×10?7–1.5×10?5 mol/L respectively.

Wavelet Analysis of Average

The identification method in the CurveExpert-1.40 software environment revealed asymmetric wavelets of changes in the average monthly temperature of New Delhi from 1931 to 2021.The maximum increment for 80 years of the average monthly temperature of 5.1℃was in March 2010.An analysis of the wave patterns of the dynamics of the average monthly temperature up to 2110 was carried out.For forecasting,formulas were adopted containing four components,among which the second component is the critical heat wave of India.The first component is the Mandelbrot law(in physics).It shows the natural trend of decreasing temperature.The second component increases according to the critical law.The third component with a correlation coefficient of 0.9522 has an annual fluctuation cycle.The fourth component with a semi-annual cycle shows the influence of vegetation cover.The warming level of 2010 will repeat again in 2035-2040.From 2040 the temperature will rise steadily.June is the hottest month.At the same time,the maximum temperature of 35.1℃in 2010 in June will again reach by 2076.But according to the second component of the heat wave,the temperature will rise from 0.54℃to 16.29°C.The annual and semi-annual cycles had an insignificant effect on the June temperature dynamics.Thus,the identification method on the example of meteorological observations in New Delhi made it possible to obtain summary models containing a different number of components.The temperature at a height of 2 m is insufficient.On the surface,according to space measurements,the temperature reaches 55°C.As a result,in order to identify more accurate asymmetric wavelets for forecasting,the results of satellite measurements of the surface temperature of India at various geographical locations of meteorological stations are additionally required.

带剪切销抗爆容器定向泄压特性研究

为优化机载抗爆容器的结构设计并拓展其工程应用,研究了带剪切销抗爆容器的定向泄压特性。利用LS-DYNA软件建立了内爆载荷下带剪切销抗爆容器的数值模型,开展了容器内爆试验,获得了剪切销临界直径,并验证了模型可靠性,阐明了抗爆容器内冲击波的传播与载荷分布规律,分析并讨论了泄压过程中泄压盖的运动规律,建立了不同泄压盖质量下药量与剪切销直径之间的函数关系,探究了剪切销的临界断裂问题。结果表明:100 g TNT内爆试验得到剪切销临界直径为22 mm,TNT爆炸后冲击波在容器内往复式传播,约3.8 ms时泄压盖冲出容器,5.0 ms时容器底部残存压力约为0.5 MPa;容器底部超压峰值约为144 MPa,罐体与泄压盖交汇形成的角隅处超压峰值约为149 MPa,且罐体在角隅处产生应变增长效应,角隅处成为新的危险点。剪切销的变形断裂过程会影响泄压盖的运动规律,导致泄压盖速度曲线中出现下降段,剪切销直径越大,下降段持续时间越长。TNT药量与剪切销临界直径呈正比,二者的线性关系不受泄压盖质量的影响。

LARGE-TIME BEHAVIOR OF SOLUTIONS OF QUANTUM HYDRODYNAMIC MODEL FOR SEMICONDUCTORS

A one-dimensional quantum hydrodynamic model （or quantum Euler-Poisson system） for semiconductors with initial boundary conditions is considered for general pressure-density function. The existence and uniqueness of the classical solution of the corresponding steady-state quantum hydrodynamic equations is proved. Furthermore, the global existence of classical solution, when the initial datum is a perturbation of t he steadystate solution, is obtained. This solution tends to the corresponding steady-state solution exponentially fast as the time tends to infinity.

Pre-Failure Behavior of Deep-Situated Osaka Clay

Great interest has been aroused on deeply-situated Osaka clay since Kobe Earthquake in 1994. In this paper is presented the analysis on the results of a series of lab tests on Osaka clay situated from 100 m to 1500 m under the ground. The wave velocity method, bender element method, LDT and the formula derived by the authors are used, focus is put on the pre-failure mechanical behavior of the clay. The analysis shows that, (i) pore-pressure coefficient B is less than 1.0, (ii) the relationship between shear modulus and Poisson's ratio is not in agreement with that reported before, (iii) the modulus measured with LDT is still less than that measured with bender element method, and (iv) there are two threshold strains, within which the clay can be considered as elastic, and both of them are larger than that reported before.

Human Activity Recognition Based on Frequency-Modulated Continuous Wave and DenseNet

With the development of wireless technology, Frequency-Modulated Continuous Wave (FMCW) radar has increased sensing capability and can be used to recognize human activity. These applications have gained wide-spread attention and become a hot research area. FMCW signals reflected by target activity can be collected, and human activity can be recognized based on the measurements. This paper focused on human activity recognition based on FMCW and DenseNet. We collected point clouds from FMCW and analyzed them to recognize human activity because different activities could lead to unique point cloud features. We built and trained the neural network to implement human activities using a FMCW signal. Firstly, this paper presented recent reviews about human activity recognition using wireless signals. Then, it introduced the basic concepts of FMCW radar and described the fundamental principles of the system using FMCW radar. We also provided the system framework, experiment scenario, and DenseNet neural network structure. Finally, we presented the experimental results and analyzed the accuracy of different neural network models. The system achieved recognition accuracy of 100 percent for five activities using the DenseNet. We concluded the paper by discussing the current issues and future research directions.

Nanometer ultrastructural brain damage following low intensity primary blast wave exposure

Blast-induced mild traumatic brain injury（m TBI） is of particular concern among military personnel due to exposure to blast energy during military training and combat.The impact of primary low-intensity blast mediated pathophysiology upon later neurobehavioral disorders has been controversial.Developing a military preclinical blast model to simulate the pathophysiology of human blast injury is an important first step.This article provides an overview of primary blast effects and perspectives of our recent studies demonstrating ultrastructural changes in the brain and behavioral disorders resulting from open-field blast exposures up to 46.6 k Pa using a murine model.The model is scalable and permits exposure to varying magnitudes of primary blast injuries by placing animals at different distances from the blast center or by changing the amount of C4 charge.We here review the implications and future applications and directions of using this animal model to uncover the underlying mechanisms related to primary blast injury.Overall,these studies offer the prospect of enhanced understanding of the pathogenesis of primary low-intensity blast-induced TBI and insights for prevention,diagnosis and treatment of blast induced TBI,particularly m TBI/concussion related to current combat exposures.

秀丽隐杆线虫对声表面波刺激的行为响应

利用频率为8.8 MHz的声表面波,刺激位于压电基底上琼脂表面秀丽隐杆线虫,研究其对超声作用的行为响应。具体地,分析了超声刺激后线虫的转向和后退行为与声表面波辐照时长、基底振动幅度及脉冲重复频率的关系,发现线虫对高频声表面波脉冲刺激的响应与此前低频体波刺激所得规律一致,即类似于可感知脉冲重复频率的带通滤波器。通过比较温度感知缺陷突变体线虫与野生型线虫的行为,明确了机械振动在诱发线虫响应中占据主导地位,而超声热效应并非主要因素。在此基础上,尝试通过信号时-空分布的调节改变声场形态,研究线虫在声场中的趋避性,进而实现对线虫转向行为的初步干预。

水下爆炸冲击波和气泡行为自由面效应的实验研究

为研究自由面对水下爆炸冲击波、气泡行为和由气泡与自由面强耦合作用形成水幕的影响,设计了小当量PETN球形装药近水面水下爆炸实验系统,开展了5种典型工况水下爆炸实验,采用高速相机和压力传感器分别获取了气泡和水幕形态演变过程、水中测点压力时间历程。根据冲击波、气泡时序特征分别分析了其自由面效应,冲击波主要变现为截断效应,气泡与自由面相互作用表现为复杂的气泡形态演化和水幕生成及演化,通过高速图像结合压力时间历程分析,进一步从气泡水平半径、中心偏移位移和水幕最大高度定量分析气泡自由面效应。结果表明:随着爆深的减小,水面反射波程差减小,自由面对冲击波的截断效应增强,即冲击波正压作用时间减小,实测截断时间差与计算时间差的最大偏差为6.81%;随着比例爆深减小,自由面效应加剧,气泡和水幕形态趋于复杂化;气泡由球形演变为卵形以及更加复杂的形态,水幕由单一的水冢,逐渐转变为水冢-顶端飞溅水柱、水冢-垂直喷射水柱-水射流等复杂形态;气泡水平半径从第2个脉动周期不再保持脉动特征过渡到第1个脉动周期,甚至到第1次气泡膨胀阶段;气泡水平半径中心偏移位移呈现出两段式变化规律,在前期偏移位移快速增加阶段(偏移位移范围0~20 mm),4种比例爆深偏移位移呈现出近似线性变化规律,线性系数相近。

基于毫米波雷达稀疏点云的人体行为识别方法

目前利用毫米波雷达进行人体行为识别的方法在复杂场景下无法很好地区分相似动作,与此同时模型的鲁棒性和抗干扰能力也相对较差;针对以上两个问题,提出了一种通用的基于毫米波雷达稀疏点云的人体行为识别方法,该方法首先利用K-means++聚类算法对点云进行采样,然后使用基于注意力特征融合的点云活动分类网络进行人体行为特征的提取和识别,该网络可以兼顾点云的空间特征以及时序特征,对稀疏点云的运动有灵敏的感知能力;为了验证所提出方法的有效性和鲁棒性,分别在MMActivity数据集和MMGesture数据集上进行了实验,并在两个数据集上取得97.50%和94.10%的准确率,均优于其它方法;此外,进一步验证了K-means++点云采样方法的有效性,相较于随机采样,准确率提升了0.4个百分点,实验结果表明所提出方法能够有效地提升人体行为识别的准确率,且模型具有较好的泛化能力。

Rosenau方程的显式行波解及动力学行为

找到Rosenau方程的显式精确解十分困难,研究方法常采用数值离散求解技术.首先,采用李群分析法给出了Rosenau方程的对称群、约化常微分方程和群不变解;其次,构造了一种精确求解非线性偏微分方程的exp(-φ(ξ))展式法,利用此方法找到了Rosenau方程的显式行波解,分析了解的动力学行为;最后,所获得的显式行波解既证明了Rosenau方程显式精确解的存在性,又可用于验证数值解的精度、检验数值离散方案的优劣,为工程领域的实际应用提供理论依据和参考.