Influence of Inter-Particle Distance, Entrapped Water Volume and Salinity of Water on the Escape Velocity of Particles on a Riverbank

The mechanism of erosion of a riverbank is not easy to analyze and each sediment particle is under influence of number of forces. Among all these forces, force of cohesion between the particles plays a very dominant and significant role, and, till date, not much progress has been made to analyze this force in a deterministic manner. A particle is bound to its neighboring particles under this force of cohesion. In this paper, the analysis of forces acting on a particle on a riverbank has been made with a model called the Truncated Pyramid Model. A particle requires a certain velocity to escape from the riverbank and determination of the escape velocity can pave the way for finding out other parameters like entrainment rate, erosion coefficient and so on. Calculation and estimation of riverbank erosion rate is an important aspect of river basin management. In this paper it has been shown that the escape velocity is dependent on certain micro-level parameters like inter-particle distance and volume of the water bridge between two adjacent particles. Also, for saline water the particle requires less velocity to escape compared to the pure-water scenario. The findings of the present paper exactly fall in line with the results of another paper where the researchers showed that cohesive force between the particles decreases as water turns from pure to impure.

A Relativistic Escape Velocity Maximum of Light Speed

There are parallels between the time distortion equations of General and Special Relativity. The time distortion in Special Relativity limits the “Real” velocity of a particle to the speed of light |c| by slowing the velocity of bosons/energy and increasing the mass of fermion||lepton (or matter) particles. In General Relativity, the gravitational slowdown of bosons/gravitons limits the escape velocity |v Esc| to light speed. |v Esc = (2GM/r)0.5| can also be written as |v Esc2 = 2GM/r|. So an alternate grammar for the equation could be The above contests currently held properties of Schwarzschild Objects. Relativistic theory predicts the slowdown of gravitons/bosons, while their velocity only approaches zero. The different mathe-matical logic of Gravitational Force ||GF|| GF = GMm/r2 would mean no limit on the force. Matter formed through compression of bosons can escape after formation by absorbing kinetic energy from the slowing photons/bosons in its surroundings. So matter formation can occur via a steady-state mechanism. The limit on v Esc allows matter to escape in events that parallel both the Big Bang and Cyclic cosmology. Additional arguments are made as to the validity of relativity.

基于Velocity的代码生成引擎的设计与实现

在软件开发过程中,采用代码生成技术可以显著减少开发者的重复性工作量。此外,还可以提升代码的质量并提高可维护性。本文讨论的代码生成引擎基于Velocity开源模板和Struts2注解,实现了模型驱动的开发模式。实践表明,其可以很好地满足基于业务对象模型生成全栈式Web应用代码的需求。

建筑热羽流影响下空气污染物跨楼层扩散特性

采用风洞实验和数值模拟,以单侧通风6层建筑为研究对象,考虑水平来流和太阳辐射引起的近壁面热羽流的耦合作用,探究了不同理查德森数Ri下建筑壁面热流运动、温度分布及污染物在竖直方向的跨楼层扩散传播特性。研究表明:当Ri≤5.64时,水平风力占主导,建筑2/3高度以下迎风面有明显的下行及向两侧的流动,1层释放的污染物对2层及以上楼层几乎没有影响,此时归一化净逃逸速度NEV~*基本保持不变;当Ri>5.64时,壁面热浮升力作用不能被忽略,随着Ri的增大,NEV~*明显增大,表明有更多污染物从1层室内扩散出来,沿迎风面向上运动的热流对高层室内产生影响,导致污染物跨楼层传播的风险增大。

基于Dijkstra算法的煤矿水灾时期最优逃生路径设计

煤矿水灾事故发生后,最棘手的问题就是如何能在最短的时间内实现安全逃生。本文通过在台东山煤矿矿工井下的实际测量,得出井下巷道的类型、坡度、风速、是否设置局部障碍物等对巷道通行难易程度影响的大小,还提出了一种新型水中逃生速度曲线模型,得出不同水位高度不同身高对巷道通行时间的影响大小,继而得出当量长度的计算公式。本文还提出了安全系数的概念,只能当巷道的安全系数值大于0.5时才具备逃生条件。然后提出了加入等高线数值考量的Dijkstra算法最优路径的求取方法,多个安全逃生出口的K则最优路径的优化,以及对K则最优路径提出了新的理解,进行了延伸。最后以台东山煤矿基础数据,以1.7 m平均身高为例,对最优逃生路径的求取进行了实验验证,对实际煤矿水灾时期的逃生具有重大的指导意义。

Generalized Newton’s Theory of Universal Gravitation and Black Holes

The Newton’s theory of universal gravitation is generalized. Significantly strong at short distances central interaction of bodies and particles is established in comparison with Newtonian. A connection is found with Black Holes, with the horizon of events. Possibility of systematization of all Black Holes is shown. An illustration is given on the example of Black Hole SgrA*.

质点沿光滑半球下滑运动的数值计算

利用Matlab编程,求解质点沿光滑半球下滑时,半球的速度和加速度随时间变化以及质点相对球心的角速度和角加速度随时间的变化,并进一步讨论了不同的初始条件对质点在半球上的运动时间及质点与半球脱离位置的影响.

Forming and breaking the ceiling of inlet gas velocity regarding to separation efficiency of cyclone

The maximum-efficiency inlet velocity(MEIV)is a ceiling of inlet gas velocity that defines separation efficiency during cyclone design and operation.Experiment and computational fluid dynamics(CFD)simulation exhibited that an apex cone at the dust outlet can break the ceiling and improve the sepa-ration efficiency.The phenomenon is closely related to the effect of excessive high inlet gas velocity on the back-mixing escape of fine particles,which is the final result of back mixing,entrainment by the rapid upward airflow,and secondary separation of the inner vortex.In the center of the inner vortex,the airflow rotates slowly and moves rapidly upward.This elevator type of airflow delivers re-entrained particles to the vortex finder.A higher inlet gas velocity accelerates the elevator,causing more entrained particles to escape.This explains the decrease in efficiency at an excessively high inlet gas velocity.When an apex cone is installed at the dust outlet,the back-mixing is significantly weakened because the vortex core is bounded to the center of separator,while the transport effect of rapid upward airflow is weakened by the decrease in axial velocity in the center.Therefore,particle escape is weakened even at excessive high inlet gas velocities.Instead,the centrifugal effect is enhanced because of increased tangential velocity of the gas and particles.Consequently,the ceiling of inlet gas velocity is broken.

原位涂覆整体式SCR催化剂的储氨性能研究

随着排放法规对氨逃逸限值日益加严,研究选择性催化还原(SCR)催化剂的储氨性能至关重要。以原位涂覆制备的铜基分子筛SCR催化剂为研究对象,采用In-situFTIRs和NH_(3)-TPD表征化学吸附特征,并根据国VI排放法规循环进行发动机台架性能测试。结果表明,在200~450℃内NOX转化率接近100%,NH_3脱附分别对应弱酸、中强酸和强酸位。其中,强酸位上形成的吸附物种NH_(4)^(+)热稳定性好。空速对SCR催化涂层氨存储影响较小,且停喷前后氨逃逸量占比与反应耗氨量占比成正相关性。300~400℃内,停喷前/停喷后氨逃逸量与反应耗氨量占比由高到低依次均是40000 h^(-1)>60000 h^(-1)>20000 h^(-1)。探明了氨存储与氨逃逸、NO_(X)转化率之间的关联性,以及空速、温度、尿素喷射等因素的影响规律,对SCR催化剂配方和尿素喷射控制策略开发提供参考。

Crustal structure of seismic velocity in southern Tibet and east-westward escape of the crustal material——An example by wide-angle seismic profile from Peigu Tso to Pumoyong Tso

The reflecting events from Moho and other interfaces within the crust are recog-nized from the wavefield characteristics of P- and S-wave for the 480km long wide-angle seismic profile between Peigu Tso and Pumoyong Tso. Then, seismic crustal structures of P- and S-wave velocities and Poisson ratio under the nearly east-west profile in southern Tibet are interpreted by fitting the observed traveltimes with the calculated ones by forward modelling. Our interpreting results demonstrate that the crustal thickness varies remarkably in the east-west direction, showing a pattern that the crust could be divided into three parts bounded by the west of Dingri and the east of Dinggy? respectively, where the depth of Moho is about 71km for the western part, about 76km for the middle and about 74km for the eastern. There is one lower velocity layer (LVL) at the bottom of the upper crust with depth of 20—30 km. One of the distinct features is that the thickness of LVL abruptly thins from 24km on the west to 6km on the east. The other is that the velocity variation in the crust along east-west direction for both P- and S-wave displays a feature as quasi-periodic variation. The lower velocity (compared to the average value for the continent of the globe) in the lower crust and three sets of north-southward active normal faults are probably attributed to the coupling process of material delamination in the lower crust, crustal thicking and east-westward escape of the crustal material accompanied with the continental col-lision between India and Eurasia Plate.

THE ACCRETION OF MOVING COSMIC STRING

The accretion of matter onto moving cosmic string is discussed carefully.It is found that the'accreting matter in the wake has not only transverse velocity but also vertical velocity.The vertical velocity of the accreting matter depends on that of moving string.

Tangent-impulse transfer from elliptic orbit to an excess velocity vector

The two-body orbital transfer problem from an elliptic parking orbit to an excess veloc-ity vector with the tangent impulse is studied. The direction of the impulse is constrained to be aligned with the velocity vector, then speed changes are enough to nullify the relative velocity. First, if one tangent impulse is used, the transfer orbit is obtained by solving a single-variable function about the true anomaly of the initial orbit. For the initial circular orbit, the closed-form solution is derived. For the initial elliptic orbit, the discontinuous point is solved, then the initial true anomaly is obtained by a numerical iterative approach; moreover, an alternative method is proposed to avoid the singularity. There is only one solution for one-tangent-impulse escape trajectory. Then, based on the one-tangent-impulse solution, the minimum-energy multi-tangent-impulse escape trajectory is obtained by a numerical optimization algorithm, e.g., the genetic method. Finally, several examples are provided to validate the proposed method. The numerical results show that the minimum-energy multi-tangent-impulse escape trajectory is the same as the one-tangent-impulse trajectory.

人造飞船逃逸地球三种方法的理论分析与数值模拟

本文从三种逃逸地球的方法——“单次点火逃逸、两次点火逃逸(Oberth效应)、三次点火逃逸(Edelbaum效应)”出发,研究讨论了三种逃逸方式在喷气变轨时消耗燃料的多少以及飞船运行时间的计算方法,并根据理论进行了VPyhton数值模拟,模拟出的飞船三种逃逸方式和理论上的情况一致,最后又根据理论进行了GeoGebra作图定量分析比较了三种逃逸方式在燃料消耗以及运行时间上的大小关系。

Partitioning Anatolian Kinematics into Tectonic Escape and Slab Rollback Dominated Domains

Anatolia is the global archetype of tectonic escape,as witnessed by the devastating 2023 Kahramanmaraş Earthquake sequence,and the 2020 Samos Earthquake,which show different kinematics related to the framework of the escape tectonics.Global Positioning System(GPS)motions of the wedge-shaped plate differ regionally from northwestwards to southwestwards(from east to west).Anatolia was extruded westward from the Arabian-Eurasian collision along the North and East Anatolian fault systems,rotating counterclockwise into the oceanic free-faces of the Mediterranean and Aegean,with dramatic extension of western Anatolia in traditional interpretations.However,which is the dominant mechanism for this change in kinematics,extrusion related to the Arabia/Eurasia collision or rollback of the African slab beneath western Anatolia is still unclear.To assess the dominant driving mechanisms across Anatolia,we analyze recent GPS velocity datasets,and decomposed them into N-S and E-W components,revealing that westward motion is essentially constant across the whole plate and consistent with the slip rates of the North and East Anatolia fault zones,while southward components increase dramatically in the transition area between central and western Anatolia,where a slab tear is suggested.This phenomenon is related to different tectonic driving mechanisms.The ArabiaEurasia collision drives the Anatolian Plate uniformly westwards while western Anatolia is progressively more affected by the southward retreating African subducting slab west of the Aegean/Cypriot slab tear,which significantly increases the southward component of the velocity field and causes the apparent curve of the whole modern velocity field.The 2020 and 2023 earthquake focal mechanisms also confirm that the northward colliding Arabian Plate forced Anatolia to the west,and the retreating African slab is pulling the upper plate of western Anatolian apart in extension.We propose that the Anatolian Plate is moving westwards as one plate with an additional component of extension in its west caused by the local driving mechanism,slab rollback(with the boundary above the slab tear around Isparta),rather than separate microplates or a near-pole spin of the entire Anatolian Plate,and the collisionrelated extrusion is the dominant mechanism of tectonic escape.

一种改进的自适应逃逸微粒群算法及实验分析

分析了变异操作对微粒群算法(particleswarmoptimization,简称PSO)的影响,针对收敛速度慢、容易陷入局部极小等缺点,结合生物界中物种发现生存密度过大时会自动分家迁移的习性,给出了一种自适应逃逸微粒群算法,并证明了它依概率收敛到全局最优解.算法中的逃逸行为是一种简化的确定变异操作.当微粒飞行速度过小时,通过逃逸运动使微粒能够有效地进行全局和局部搜索,减弱了随机变异操作带来的不稳定性.典型复杂函数优化的仿真结果表明,该算法不仅具有更快的收敛速度,而且能更有效地进行全局搜索.

一种基于单纯形法的改进微粒群优化算法及其收敛性分析

针对现有微粒群优化算法难以兼顾进化速度和求解质量这一难题,提出一种基于单纯形法的改进微粒群优化算法(Simplex method based improved particle swarm optimization,SM-IPSO).该算法采用多个优化种群,分别在奇数种群和偶数种群上并行运行微粒群算法和单纯形法,并通过周期性迁移相邻种群间的最优信息,达到微粒群算法和单纯形法的协同搜索:单纯形借助微粒群算法跳出局部收敛点,微粒群依靠单纯形提高局部开发能力.为强化两种算法所起作用,一种改进的微粒速度逃逸策略和Nelder-Mead单纯形法也被提出.最后,在Linux集群系统上运行所提算法,通过优化五个典型测试函数验证了算法的有效性.

潜艇集体逃生舱上浮水动力性能

针对潜艇集体逃生舱上浮过程的水动力问题,建立了典型集体逃生舱水下运动的数学模型,并重点对其释放后的上浮速度进行了数学仿真计算。然后,根据该流场的特点,合理选择求解条件,利用Fluent软件进行仿真分析。两种计算方法的结果吻合较好,结果表明:该集体逃生舱水下运动数学模型是正确的,其稳定上浮速度较大,在设计中应当进行控制。

载人航天器月地返回再入问题研究

结合国外探月返回再入飞行的工程实践情况,对国外载人航天器月地返回再入几何约束、再入走廊约束、航天员过载限制约束,以及再入轨道、再入航程、再入方式和气动外形的选择策略进行了研究和分析。文章的研究结果可为我国载人探月及载人深空探测航天器返回再入设计提供参考。

煤层气开采过程中的逸散

分析煤层气的赋存方式、成藏过程以及开采过程中的逸散问题,通过定义逸散速度比与逸散距离比,提出了判断煤层气在开采过程中是否发生逸散的条件,模拟计算了开采过程中的煤层气逸散量及其分布情况,同时研究了围岩渗透率、煤层的初始含气量以及气井产量对煤层气逸散量的影响。若煤层气逸散距离比大于逸散速度比的最大值,则可以认为煤层气无法发生逸散。实例计算表明,距离井筒越远越容易发生逸散;开采过程中煤层气的逸散可以损失10%~15%储量,超过占储量10%的煤层气是在开采初期逸散的。高含气量和低含气量的煤层气在开采过程中的逸散量较少,而中等含气量的煤层气逸散较多。减少开采过程中煤层气逸散量的关键是在煤层中快速建立生产压差,实现开发初期的快速生产。

基于Helbing模型某化学品船机舱火灾人员逃生仿真研究

基于Helbing模型,对某型化学品船机舱火灾发生时人员逃生进行了三维数值模拟.在考虑火灾探测延时的情况下,计算了火灾综合因素影响下的逃生速度、人数与时间的变化关系.结果表明:在火场内综合因素的影响下,人员逃生速度迅速降低,并且机舱下层平台人员中尚有两人未安全逃生.根据计算结果分析该船机舱布置存在的问题,为类似化学品船的结构布置及机舱消防系统的设计提供参考.