Experimental Study on the Mechanical Parameters Relating to the Impact Tendency of Coal Sample

Coal burst remains one of the gravest safety risks that will be encountered in mining in the future, because the stress conditions will become more complex as mining depths increase. Various influencing elements exist, and varied geological and mining circumstances might result in diverse coal burst phenomena. The impact propensity of coal has variations as a result of the distinct physical and mechanical qualities of each. To identify the impact propensity of coal and then understand the rules of coal burst occurrence, laboratory tests can be conducted to identify the physical and mechanical parameters affecting coal samples. The mechanical properties, energy absorption, and energy dissipation characteristics of coal samples were examined experimentally in this paper using coal samples that were taken from the mine. On the basis of the evaluation of the impact inclination parameters for four fundamental coal samples, novel impact inclination indicators and the relationship between the fractures in the coal sample and the impact inclination parameters were discussed. The following are the key conclusions: 1) On-site samples of No. 15 coal from the Qi yuan Coal Mine were taken (15 s) and processed in accordance with the guidelines for the coal specimen impact inclination test. The accuracy of the specimen was sufficient for the test. 2) Analysis is done on the mechanical relevance and calculation techniques of the four fundamental coal sample impact tendency characteristics, dynamic failure time (DT), elastic strain energy index (WET), impact energy index (KE), as well as uniaxial compressive strength (RC). 3) Regarding the rock burst danger of rock samples, the potential use of the ratio of pre-peak and post- peak deformation modulus to Kλ and the residual elastic strain energy index CEF as the impact propensity indices of coal samples are discussed. It is possible to utilize two new impact propensity indices to evaluate the impact propensity of coal samples, according to test results that reveal a linear correlation between two new impact inclination indexes and four fundamental impact tendency indexes. 4) The statistical analysis of the crack ratio with the four impact propensity indicators after coal specimen failure, and the correlation among the crack ratio with the indicators, are both done. The findings indicate that the four impact propensity indicators have a linear relationship with the crack ratio of the coal sample surface cracks.

Impact parameter and beam energy dependence for azimuthal asymmetry of direct photons and free protons in intermediate energy heavy-ion collisions

Hard photon emitted from energetic heavy ion collisions is of very interesting since it does not experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we have calculated the impact parameter and beam energy dependence for azimuthal asymmetry, characterized by directed transverse flow parameter F and elliptic asymmetry coeffcient v2, of direct photons and the corresponding free protons in intermediate energy heavy-ion collisions. It is further shown the anti-correlated azimuthal asymmetry between direct photons and free protons.

Impact parameter dependence of the scaling of anisotropic flows in intermediate energy heavy-ion collisions

The scaling behaviors of anisotropic flows of light charged particles are studied for 25 MeV/u 40Ca＋40Ca collisions at different impact parameters by the isospin-dependent quantum molecular dynamics model. The nucleon- number scaling of elliptic flow exists and the scaling of the ratios of v4/v2 2 and v3/（v1v2） is applicable to collisions at almost all impact parameters except for peripheral collisions.

Determination of the impact parameter in high-energy heavy-ion collisions via deep learning

In this study,Au+Au collisions with an impact parameter of 0≤b≤12.5 fm at√(s_(NN))=200 GeV are simulated using the AMPT model to provide preliminary final-state information.After transforming this information into appropriate input data(the energy spectra of final-state charged hadrons),we construct a multi-layer perceptron(MLP)and convolutional neural network(CNN)to connect final-state observables with the impact parameters.The results show that both the MLP and CNN can reconstruct the impact parameters with a mean absolute error approximately 0.4 fm,although the CNN behaves slightly better.Subsequently,we test the neural networks at different beam energies and pseudorapidity ranges in this task.These two models work well at both low and high energies.However,when conducting a test for a larger pseudorapidity window,the CNN exhibits a higher prediction accuracy than the MLP.Using the Grad-CAM method,we shed light on the'attention'mechanism of the CNN model.

ρ meson impact parameter distributions

In this paper, the p meson impact parameter dependent parton distributions and the impact parameter dependent form factors are introduced and discussed. By employing a Gaussian form wave packet, we calculate the impact parameter distributions of the p meson based on a light-cone constituent quark model.

过载和攻击时间约束下的非线性最优制导方法

考虑导弹过载受限条件下,对以期望时间为攻击目标的非线性最优制导问题进行了研究。首先,建立了非线性最优制导问题的理论模型,基于庞特里亚金极大值原理和饱和函数方法建立了最优轨迹的最优性条件。其次,根据最优性条件和哈密尔顿轨迹参数化方法,建立了最优轨迹的参数化微分方程组,使得通过数值积分即可生成从飞行状态到最优制导指令映射关系的数据集。然后,通过前馈神经网络对上述映射关系进行近似,实现了非线性最优制导指令的毫秒量级实时生成。最后,通过数值仿真验证了所提非线性最优制导指令生成方法的有效性。

Performance of the Wind Farm Parameterization Scheme Coupled with the Weather Research and Forecasting Model under Multiple Resolution Regimes for Simulating an Onshore Wind Farm

We use the Wind Farm Parameterization(WFP) scheme coupled with the Weather Research and Forecasting model under multiple resolution regimes to simulate turbulent wake dynamics generated by a real onshore wind farm and their influence at the local meteorological scale. The model outputs are compared with earlier modeling and observation studies. It is found that higher vertical and horizontal resolutions have great impacts on the simulated wake flow dynamics. The corresponding wind speed deficit and turbulent kinetic energy results match well with previous studies. In addition, the effect of horizontal resolution on near-surface meteorology is significantly higher than that of vertical resolution. The wake flow field extends from the start of the wind farm to downstream within 10 km, where the wind speed deficit may exceed 4%. For a height of 150 m or at a distance of about 25 km downstream, the wind speed deficit is around 2%. This indicates that, at a distance of more than 25 km downstream, the impact of the wind turbines can be ignored. Analysis of near-surface meteorology indicates a night and early morning warming near the surface, and increase in near-surface water vapor mixing ratio with decreasing surface sensible and latent heat fluxes. During daytime, a slight cooling near the surface and decrease in the near-surface water vapor mixing ratio with increasing surface sensible and latent heat fluxes is noticed over the wind farm area.

Numerical analysis of hydroabrasion in a hydrocyclone

The velocity profiles and separation efficiency curves of a hydrocyclone were predicted by an Euler-Euler approach using a computational fluid dynamics tool ANSYS-CFX 14.5. The Euler-Euler approach is capable of considering the particle-particle interactions and is appropriate for highly laden liquid-solid mixtures. Pre- dicted results were compared and validated with experi- mental results and showed a considerably good agreement. An increase in the particle cut size with increasing solid concentration of the inlet mixture flow was observed and discussed. In addition to this, the erosion on hydrocyclone walls constructed from stainless steel 410, eroded by sand particles （mainly SiOz）, was predicted with the Euler-La- grange approach. In this approach, the abrasive solid particles were traced in a Lagrangian reference frame as discrete particles. The increases in the input flow velocity, solid concentration, and the particle size have increased the erosion at the upper part of the cylindrical body of the hydrocyclone, where the tangential inlet flow enters the hydrocyclone. The erosion density in the area between the cylindrical to conical body area, in comparison to other parts of the hydrocyclone, also increased considerably. Moreover, it was observed that an increase in the particle shape factor from 0.1 to 1.0 leads to a decrease of almost 70 % in the average erosion density of the hydrocyclone wall surfaces.

2-D Numerical Simulation of Natural Gas Hydrate Decomposition Through Depressurization by Fully Implicit Method

Natural gas hydrate, as a potential energy resource, deposits in permafrost and marine sediment with large quantities. The current exploitation methods include depressurization, thermal stimulation, and inhibitor injection. However, many issues have to be resolved before the commercial production. In the present study, a 2-D axisymmetric simulator for gas production from hydrate reservoirs is developed. The simulator includes equations of conductive and convective heat transfer, kinetic of hydrate decomposition, and multiphase flow. These equations are discretized based on the finite difference method and are solved with the fully implicit simultaneous solution method. The process of laboratory-scale hydrate decomposition by depressurization is simulated. For different surrounding temperatures and outlet pressures, time evolutions of gas and water generations during hydrate dissociation are evaluated, and variations of temperature, pressure, and multiphase fluid flow conditions are analyzed. The results suggest that the rate of heat transfer plays an important role in the process. Furthermore, high surrounding temperature and low outlet valve pressure may increase the rate of hydrate dissociation with insignificant impact on final cumulative gas volume.

三级阀控液压操动机构建模及冲击特性研究

针对高速大功率三级阀控液压缸操动机构在冲击载荷下压力波动剧烈、制动末速度较大、相应实验成本高、部分实验参数难以获取等问题,结合主阀的实际复杂结构,采用综合建模与实验验证的方法建立三级阀和液压缸非线性动力学模型;分析阀控液压缸系统的位移、速度和冲击压力特性;研究柱塞参数(长度、直径、初始间隙)、柱塞形状与冲击压力峰值、制动末速度之间的关系,并确定合理取值区间与合适的柱塞形状。结果表明:液压缸柱塞结构和设计参数是导致阀控液压缸操动系统冲击压力峰值过高、制动末速度较大的主要原因;圆锥型柱塞对降低液压缸压力波动及制动末速度的效果显著。

基于AERMOD模式的大气扩散参数方案比较研究

在美国法规空气质量模式AERMOD的框架下,比较了4种已被广泛应用的扩散参数化方案(基于边界层微气象要素的AERMOD湍流参数化方案,基于湍流观测资料和扩散函数的Tub-Obs方案,Briggs参数化方案,NEPA方案).分析了不同稳定度、不同扩散参数方案下的污染物SO2地表浓度差别.总体来说,在中性和不稳定条件下,4种方案模拟结果的差别不大;在稳定条件下,AERMOD方案的地面浓度明显低于Briggs和NEPA方案,可能是由于AERMOD方案不能很好地识别局地湍流的贡献.

海面风应力拖曳系数参数化方案对风暴潮数值模拟的影响

为了比较不同的海面风应力拖曳系数参数化方案在风暴潮数值模拟中的效果,采用9种不同的风应力拖曳系数参数化方案对湛江附近海域15个热带气旋风暴潮进行数值模拟。模拟结果表明,不同风应力拖曳系数参数化方案对热带气旋风暴潮增水最大值的数值模拟效果不完全相同,在风暴潮数值模拟中要选择合适的风应力拖曳系数参数化方案;文中Smith(1980)、Yelland和Taylor(1998)风应力拖曳系数参数化方案增水最大值模拟的误差较小,这也说明两种参数化方案在风暴潮数值模拟中外推到热带气旋高风速范围内是可行的。另外,数值模拟结果也表明,在选择合适海面风应力参数化方案情况下,文中采用的风暴潮模式对强热带气旋增水的数值模拟效果较好。

Quantum Mechanical Approach for Rutherford Scattering and Nuclear Scattering with Born Approximation

Rutherford classical scattering theory, as its quantum mechanical analogue, is modified for scattering cross-section and the impact parameter by using quantum mechanical momentum, (de Broglie hypothesis), energy relationship for matter oscillator (Einstein’s oscillator) and quantum mechanical wave vectors, and , respectively. It is observed that the quantum mechanical scattering cross-section and the impact parameter depended on inverse square law of quantum action (Planck’s constant). Born approximation is revisited for quantum mechanical scattering. Using Bessel and Neumann asymptotic functions and response of nuclear surface potential barrier, born approximations were modified. The coulombic fields inside the nucleus of the atom are studied for reflection and transmission with corresponding wave vectors, phase shifts and eigenfunctions Bulk quantum mechanical tunneling and reflection scattering, both for ruptured and unruptured nucleus of the atom, are deciphered with corresponding wave vectors, phase shifts and eigenfunction. Similar calculation ware accomplished for quantum surface tunneling and reflection scattering with corresponding wave vectors, phase shifts and eigenfunctions. Such diverse quantum mechanical scattering cross-section with corresponding wave vectors for tunneling and reflection, phase shifts and eigenfunctions will pave a new dimension to understanding the behavior of exchange fields in the nucleus of the atom with insides layers both ruptured and unruptured. Phase shifts, δl for each of the energy profile (partial) will be different and indeed their corresponding wave vectors for exchange energy eigenvalues.

不同对流参数化方案试验中凝结加热的特征及对暴雨中尺度模拟结果的影响

使用20 km分辨率的MM5模式,分别选用KUO,GRELL,KAIN-FRITSCH和BETTS-MILLER(以下简称KU,GR,KF和BM)等4种不同对流参数化方案,对1996年8月3～4日石家庄特大暴雨过程作数值模拟试验,分析比较了4个不同试验中网格尺度(显式方案)和次网格尺度(对流参数化方案)凝结加热的水平、垂直分布和时变特征;研究探讨了凝结加热分布及差异对暴雨中尺度模拟结果的可能影响.分析显示,暴雨过程中,4个不同对流参数化方案试验所得到的次网格尺度凝结加热基本都呈单峰特征、加热峰值在对流层中层,但加热层厚度和强度在不同试验间存在差别;4个试验的网格尺度凝结加热的垂直范围表现出较好的一致性,加热重心位于对流层低层,但加热强度仍有所不同;GR和KF及BM试验的总凝结加热率的垂直分布特征主要受其网格尺度凝结加热率特征的影响、加热重心在对流层低层,而KU试验的总凝结加热率的垂直分布特征由其次网格尺度凝结加热率特征所决定、加热重心在对流层中层.研究表明,尽管4个试验在暴雨期间总凝结加热的垂直分布差异并不显著,但对暴雨中尺度模拟的影响却不能忽视.凝结加热的分布特征及演变直接影响与暴雨发生发展密切关联的物理量场的中尺度结构和演变;凝结加热对暴雨中尺度的影响具有连锁性,由加热差异波及局部环流细致结构和强度及其变化的差异,进而影响暴雨发生发展的细致特征.在20 km或更高一些分辨率的条件下,对于描述温带/中纬度暴雨的发展和结构,选用KF方案得到的模拟结果可能更具物理合理性;而KU方案模拟结果容易出现格点气柱的水汽和温度被过量调整的不合理情况.要得到一个可信的中尺度模拟结果,对降水模拟结果进行细化特征的验证、特别是随时间演变特征的验证分析是非常重要的,因为降水的细致演变特征与凝结加热及与之相联系的物理量场的中尺度演变特征密切关联.

不同积云对流参数化方案对华南气温和降水模拟的影响

[目的]研究4种积云对流参数化方案在华南地区气候模拟中的适用性。[方法]利用意大利国际理论物理研究中心(ICTP)发展的最新版区域气候模式RegCM4,选用Anthes-Kuo(KUO)、Grell-Arakawa&Schubert(GAK)、Grell-Fritsch&Chappell(GFC)和MIT-Emanuel(MIT)4种积云对流参数化方案,分别对华南地区气候进行了长达10年(2000～2009年)的高分辨率(水平分辨率25 km)数值积分,对比研究了4种不同积云参数化方案模拟的华南地区温度和降水的差异。[结果]对比同期Climatic Research Unit(CRU)观测的地面温度和降水资料,4种积云参数化方案基本上均抓住了华南地区温度和降水的时空分布特征,但对温度模拟出了-2℃(1℃)的冷(暖)偏差,且均低估了华南地区的降水,尤其是GAK和KUO方案,相对CRU观测低估降水50%左右;KUO和MIT方案对温度的模拟比其他2个方案优秀,而MIT和GFC对降水的模拟比KUO和GAK优秀。[结论]研究结果为RegCM4在华南地区的应用提供参考。

基于隐式参数化技术的车门内饰板安全性设计

合理设计车门内饰板形状和厚度可以有效地降低乘员损伤程度,同时减少内饰板质量。将隐式参数化技术运用在车门内饰板开发过程中,建立了参数化车门子系统有限元模型,利用多目标优化算法在近似模型基础上优化扶手形状和内饰板厚度。案例表明:该方法可以成功的解决车门内饰板安全性设计和轻量化要求的多目标问题,大大缩短开发周期。

中量级强冲击试验机摆锤部分的优化设计

中量级强冲击试验机的摆锤部分是整个实验机的核心,它的品质将决定整个试验的质量,在很大程度上也决定了整个试验机的使用寿命。因此,对其进行优化便势在必行。将中量级强冲击试验机摆锤部分进行结构简化,得出摆锤部分若干个典型的参数,以转动中心转轴所受冲量为研究对象,列出各参数与转动中心转轴所受冲量之间的关系式。应用MATLAB软件计算对应的结果。根据得出的数据,对试验机摆锤部分进行优化设计,从而达到减少转动中心转轴磨损,提高摆锤使用可靠性与寿命的目的。

Deuteron electromagnetic form factors in transverse plane with a phenomenological Lagrangian approach

A phenomenological Lagrangian approach is employed to study the electromagnetic properties of deuteron The deuteron is regarded as a loosely bound state of a proton and a neutron. The deuteron electromagnetic form factors are expressed in light-front representation in the transverse plane. The transverse charge density of the deuteron is discussed.

Study of the total reaction cross section via QMD

This paper presents a new empirical formula to calculate the average nucleon-nucleon （N-N） collisi011 number for the total reaction cross sections （aR）. Based on the initial average N-N collision number calculated by quantum molecular dynamics （QMD）, quantum correction and Coulomb correction are taken into account within it. The average N-N collision number is calculated by this empirical formula. The total reaction cross sections are obtained within the framework of the Glauber theory, aR of 23A1＋1：C, anAl＋12C, 25A1＋12C, 26A1＋12C and 27A1＋12C are calculated in the range of low energy. We also calculate the an of 27A1＋12C with different incident e^ergies. The calculated aR are compared with the experimental data and the results of Glauber theory including the aa of both spherical nuclear and deformed nuclear. It is seen that the calculated aR are larger than GR of spherical nuclear and smaller than aa of deformed nuclear, whereas the results agree well with the experimental data in low-energy range.