Multi-Barycenter Mechanics, N-Body Problem and Rotation of Galaxies and Stars

In the present paper, the establishment of a systematic multi-barycenter mechanics is based on the multi-particle mechanics. The new theory perfects the basic theoretical system of classical mechanics, which finds the law of mutual interaction between particle groups, reveals the limitations of Newton’s third law, discovers the principle of the intrinsic relationship between gravity and tidal force, reasonably interprets the origin and change laws for the rotation angular momentum of galaxies and stars and so on. By applying new theory, the multi-body problem can be transformed into a special two-body problem and for which an approximate solution method is proposed, the motion law of each particle can be roughly obtained.

Experimental study and numerical simulation of the impact of under-sleeper pads on the dynamic and static mechanical behavior of heavy-haul railway ballast track

Laying the under-sleeper pad(USP)is one of the effective measures commonly used to delay ballast degradation and reduce maintenance workload.To explore the impact of application of the USP on the dynamic and static mechanical behavior of the ballast track in the heavy-haul railway system,numerical simulation models of the ballast bed with USP and without USP are presented in this paper by using the discrete element method(DEM)-multi-flexible body dynamic(MFBD)coupling analysis method.The ballast bed support stiffness test and dynamic displacement tests were carried out on the actual operation of a heavy-haul railway line to verify the validity of the models.The results show that using the USP results in a 43.01%reduction in the ballast bed support stiffness and achieves a more uniform distribution of track loads on the sleepers.It effectively reduces the load borne by the sleeper directly under the wheel load,with a 7.89%reduction in the pressure on the sleeper.Furthermore,the laying of the USP changes the lateral resistance sharing ratio of the ballast bed,significantly reducing the stress level of the ballast bed under train loads,with an average stress reduction of 42.19 kPa.It also reduces the plastic displacement of ballast particles and lowers the peak value of rotational angular velocity by about 50%to 70%,which is conducive to slowing down ballast bed settlement deformation and reducing maintenance costs.In summary,laying the USP has a potential value in enhancing the stability and extending the lifespan of the ballast bed in heavy-haul railway systems.

The main causes and corresponding solutions of skin pigmentation in the body

The skin's normal color is primarily determined by the quantity and distribution of pigment,the level of hemoglobin in the skin's blood vessels,and various optical factors.Additionally,mechanical damage from clothing renders certain areas of the body more susceptible to hyperpigmentation,such as the elbows and knees.According to research,various factors such as gender and weight have been found to influence skin color.The mechanism of body skin pigmentation has been extensively studied with a particular focus on melanogenesis and related signaling pathways.Therefore,this article primarily focuses on elucidating the mechanisms governing body pigmentation while discussing strategies for managing skin whitening,encompassing influential factors and whitening methods.

Pseudo-rigid-body Model for Corrugated Cantilever Beam Used in Compliant Mechanisms

Common compliant joints generally have limited range of motion, reduced fatigue life and high stress concentration. To overcome these shortcomings, periodically corrugated cantilever beam is applied to design compliant joints. Basic corrugated beam unit is modeled by using pseudo-rigid-body method. The trajectory and deformation behavior of periodically corrugated cantilever beam are estimated by the transformation of coordinate and superposition of the deformation of corrugated beam units. Finite element analysis（FEA） is carried out on corrugated cantilever beam to estimate the accuracy of the pseudo-rigid-body model. Results show that the kinetostatic behaviors obtained by this method, which has a relative error less than 6%, has good applicability and corrugated cantilever beam has the characteristics of a large range of motion and high mechanical strength. The corrugated cantilever beam is then applied to design a flexible rotational joint to obtain a larger angle output. The paper proposes a pseudo-rigid-body model for corrugated cantilever beam and designed a flexible rotational joint with large angle output.

Joint Bearing Mechanism of Coal Pillar and Backfilling Body in Roadway Backfilling Mining Technology

In the traditional mining technology,the coal resources trapped beneath surface buildings,railways,and water bodies cannot be mined massively,thereby causing the lower coal recovery and dynamic disasters.In order to solve the aforementioned problems,the roadway backfilling mining technology is developed and the joint bearing mechanism of coal pillar and backfilling body is presented in this paper.The mechanical model of bearing system of coal pillar and backfilling body is established,by analyzing the basic characteristics of overlying strata deformation in roadway backfilling mining technology.According to the Ritz method in energy variation principle,the elastic solution expression of coal pillar deformation is deduced in roadway backfilling mining technology.Based on elastic-viscoelastic correspondence principle,combining with the burgers rheological constitutive model and Laplace transform theory,the viscoelastic solution expression of coal pillar deformation is obtained in roadway backfilling mining technology.By analyzing the compressive mechanical property of backfilling body,the time formula required for coal pillar and backfilling body to play the joint bearing function in roadway backfilling mining technology is obtained.The example analysis indicates that the time is 140 days.The results can be treated as an important basis for theoretical research and process design in roadway backfilling mining technology.

Compression failure conditions of concrete-granite combined body with different roughness interface

Bedrock and concrete lining are typical composite structures in the engineering field and the stability of the geological body and engineering body is directly connected to the mechanical properties of the composite body.Under this background,the study provides the transverse isotropic equivalent model of concrete-granite double-layer composite based on the notion of strain energy equivalence.Assuming that the strength failure of concrete and granite meets the Mohr-Coulomb criterion,then the strength failure model of the combined body considering the joint roughness coefficient(JRC)is derived,and the influences of JRC,the height ratio of concrete to granite,and confining pressure on the strength failure characteristics of the combined body are emphatically analyzed.Finally,the model applicability is illustrated by the uniaxial and triaxial compression tests on concrete monomer,granite monomer and concretegranite composite samples(CGCSs)with different JRCs.The results revealed that the compressive strength of the composite is closer to the concrete with lower strength in the combined body under different confining pressures.Adding interface roughness causes to raise the compressive strength of the composite due to interfacial adhesion between concrete and granite,and a slowing growth trend is observed in compressive strength as roughness.The model can provide a certain reference for the stability design and evaluation of engineering rock mass.

A 3-DOF Pseudo-Rigid-Body Model for Tension-Based Compliant Bistable Mechanisms

Compliant bistable mechanisms, devices with two distinct stable equilibrium positions, are used in a variety of applications, such as switches, clasps, and valves. Many kinds of compliant bistable mechanisms were proposed and studied during the past decade. Among them, tension-based compliant bistable mechanisms, that incorporate tension pivots as their flexible members, feature in short travel distance and low power consuming. So far, the design of this kind of bistable mechanisms is done using finite element method through trial and error, thus is time-consuming. By treating the tension pivots as fixed-guided segments and their elongation as a spring, we developed a novel three degree-of-freedom （3-DOF） pseudo-rigid-body model （PRBM） for this kind of bistable mechanisms. The principle of virtual work is used to derive the force-deflection relationship of the PRBM model. The comparison between the PRBM results and the experimental results of the force-deflection characteristics shows that the PRBM can predict not only the bistable behavior of the tension-based bistable mechanisms, but also their soft spring-like post-bistable behavior and the spring-like force-deflection characteristics when pulling in the reverse direction from the as-fabricated position, which is called reverse behavior. The 3-DOF PRBM can be used to design and identify tension-based bistable mechanisms. Using the PRBM instead of the trial-and-error method can greatly reduce the development time of this kind of bistable mechanisms.

Mechanical Method on Bimaterial Body Boundary with Crack-tip

The problem of bimaterial body boundary, especially, microcosmic and macroscopic boundary behavior of bimetallic boundary, ceramic and metal, is paid close attention by many scholars in electronic device and communication, material science, aeronautical and astronautical engineering and et al. Modern photoelectric technology, such as laser technique, conveniently is used to measure geometrical stress field of bimaterial body, quantitatively analyse boundary mechanical behavior with crack-tip and composition of boundary matter element. One has put forward mechanical model, which is used to analyze joint energy, atom transition of matter of medium layer, diffusion and solid solution, by means of energy theory of quasi- continuous body. This paper recommended the theory, technology, and gives the results.

MATERIAL MULTIPOLE MECHANICS OF ELASTIC DIELECTRIC COMPOSITES

The overall mechanical and electrical behaviors of elastic dielectric composites are investigated with the aid of the concept of material multipoles. In particular, by introducing a statistical continuum material multipole theory, the effects of the electric-elastic interaction and the microstructure (size, shape, orientation,...) of inhomogeneous particles on the overall behaviors of the composites can be obtained. A basic solution for an ellipsoidal elastic inhomogeneity with electric polarization in an infinite elastic dielectric medium is first given, which shows that classical Eshelby 's elastic solution is modified by the presence of electric-elastic interaction. The overall macroscopic constitutive relations and their overall macroscopic material parameters accounting for electroelastic interaction effect are then derived for the elastic dielectric composites. Some quantitative calculations on the problems with statistical anisotropy, the shape effect and the electric-elastic interaction are finally given for dilute composites.

General Theory of Body Contouring: 2. Modulation of Mechanical Properties of Subcutaneous Fat Tissue

Subcutaneous white adipose tissue (sWAT) can be described micromechanically as a foam structure. It is shown that according to this model, mechanical stiffness of this tissue is primarily dependent on the average cell size and is almost independent of the dispersion of cell sizes in a local adipocytes’ population. Whereas the influence of natural fat renewal process with a rate of 10% per year must be of minor importance for mechanical properties of sWAT, induced adipocytes’ death can substantially reduce local sWAT stiffness. The sWAT which contains two or more different subpopulations of adipocytes of varying sizes with a spatially clustered structure can demonstrate significant inhomogeneity of their mechanical properties when compared with those of sWAT consisting of a single population of adipocytes. It is proposed that this effect may be an important pathophysiological feature of cellulite. Transformation of the cell shape from quasispherical to wrinkled or elliptical forms makes adipocytes more susceptible to thermo-mechanical stress reducing the strain needed to achieve the local plastic deformation. These mechanical features of sWAT are essential for understanding the mechanisms of different non-invasive and minimal invasive body contouring procedures.

The Massage Therapy of Balancing the Mechanism of the Body

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Conservation of Energy in Classical Mechanics and Its Lack from the Point of View of Quantum Theory

It is pointed out that the property of a constant energy characteristic for the circular motions of macroscopic bodies in classical mechanics does not hold when the quantum conditions for the motion are applied. This is so because any macroscopic body—lo-cated in a high-energy quantum state—is in practice forced to change this state to a state having a lower energy. The rate of the energy decrease is usually extremely small which makes its effect uneasy to detect in course of the observations, or experiments. The energy of the harmonic oscillator is thoroughly examined as an example. Here our point is that not only the energy, but also the oscillator amplitude which depends on energy, are changing with time. In result, no constant positions of the turning points of the oscillator can be specified;consequently the well-known variational procedure concerning the calculation of the action function and its properties cannot be applied.

The Yukawa potential in semirelativistic formulation via supersymmetry quantum mechanics

We apply an approximation to the centrifugal term and solve the two-body spinless-Salpeter equation （SSE） with the Yukawa potential via the supersymmetric quantum mechanics （SUSYQM） for arbitrary quantum numbers. Useful figures and tables are also included.

Mechanical Design of Long-Term Body-Adhered Medical Devices to Maximize On-Body Survival

Long-term, body-adhered medical devices rely on an adhesive interface to maintain contact with the patient. The greatest threat to on-body adhesion is mechanical stress imparted on the medical device. Several factors contribute to the ability of the device to withstand such stresses, such as the mechanical design, shape, and size of the device. This analysis investigates the impact that design changes to the device have on the stress and strain experienced by the system when acted on by a stressor. The analysis also identifies the design changes that are most effective at reducing the stress and strain. An explicit dynamic finite element analysis method was used to simulate several design iterations and a regression analysis was performed to quantify the relationship between design and resultant stress and strain. The shape, height, size, and taper of the medical device were modified, and the results indicate that, to reduce stress and strain in the system, the device should resemble a square in shape, be short in height, and small in size with a large taper. The square shape experienced 17.5% less stress compared to the next best performing shape. A 10% reduction in device height resulted in a 21% reduction in stress and 24% reduction in strain. A 20% reduction in device size caused a 7% reduction in stress and 2% reduction in strain. A 20% increase in device taper size led to a negligible reduction in stress and a 6% reduction in strain. The height of the device had the greatest impact on the resultant stress and strain.

以糖厂为主体的甘蔗机收推进模式

近年来,我国甘蔗种植面积逐年减少,切段式甘蔗联合收获机保有量大幅增加,机收率却多年低位徘徊。针对这一问题,本文从方法论视角阐明当前甘蔗产业生产关系与新质生产力之间的矛盾,是机收推进缓慢的主要原因。提出以提高甘蔗产业的竞争力和促进产业可持续发展为目标,调整甘蔗产业当前生产关系,将当前生产关系中的各方组成机收推进联合体,构建以糖厂为主体的机收推进模式。该模式以免费或低价机收为杠杆,糖厂组织、协调、管理甘蔗机械化生产,实现了糖厂有稳定优质蔗源、机收组织效益稳定、蔗农获得免费(或低价)砍收甘蔗,达到多方共赢,有利于稳定甘蔗种植面积和甘蔗产业可持续发展。以该模式为抓手,建立试点并推广应用,在当前条件下,有望打破目前机收推进缓慢僵局,实现甘蔗机收快速推进。

基于交通事故案例的3岁儿童乘员损伤机制研究

目的通过再现真实交通事故案例探究3岁儿童乘员碰撞损伤机制。方法应用车辆有限元模型和图斯特3岁儿童乘员损伤仿生模型(TUST IBMs 3YO-O),再现CIREN数据库中的交通事故案例,通过综合分析Δv、车辆质量和变形能反求碰撞前车辆的速度,设置碰撞仿真试验再现案例所描述的儿童乘员损伤,分析损伤机制。结果TUST IBMs 3YO-O模型完整地再现出碰撞事故中儿童乘员的损伤。儿童乘员头部运动学响应与生物力学响应表现出差异性,儿童乘员胸腔内部组织器官生物力学响应表明其没有出现损伤,但是胸部3 ms合成加速度达到54 g,超出阈值。结论未来乘员安全评价需要引入生物力学参数。应用高生物逼真度的人体生物力学模型再现交通事故中乘员损伤,不仅更加清晰观察事故中乘员的运动学响应,深度分析碰撞损伤机制,还为数字化评估提供参考依据,也将为儿童乘员保护装置研发和安全法规制定提供参考。

急倾斜极薄矿脉小型机械化留矿法开采采场稳定性分析

基于珊瑚钨矿急倾斜极薄矿脉小型机械化留矿法开采工艺,采用数值模拟方法分析了开采过程中采场的稳定性,探讨了采场长度、相邻采场开采时应控制的安全距离和回采顺序。结果表明:1)矿体采出后,采场上下盘围岩发生以水平向位移为主的相向位移,采空区上下两端与顶底板接触位置发生应力集中,采空区两侧围岩应力降低;2)采场长度对采场稳定性的影响较小,为提高单条采场生产能力,采场长度可由试验阶段的100 m增加到150~200 m;3)为减小相邻采场开采扰动,相邻采场开采时的安全距离应控制在4 m以上,局部地段围岩条件较差时还应适当加大;4)对于上下相邻采场,待采矿体位于已采采场的下盘围岩移动范围更有利于采场稳定性控制,建议采用从上向下的回采顺序。研究结果可为采矿工程实践提供一定的参数参考。

融合注意力机制的人体部位细分类方法

针对传统人体部位体型分类方法费时费力、成本较高的问题,设计一种融合注意力机制的体型分类网络(Attention Body Classification Net,A_BCN)。该网络由弱监督的注意力学习和数据增强两个模块组成,其中:弱监督的注意力学习模块通过注意力机制获得注意力图;数据增强模块通过注意力图指导图像的数据增强,包括注意力裁剪、注意力丢弃和注意力平均。将增强后的图像重新输入到网络中得到特征图,将得到的特征图和注意力图融合进行分类。在后续自制的人体图像数据集中,该算法准确率为90.52%,提高了分类准确率并节省了成本。

融合石膏组分和微纳米结构“双基因”调控的铁尾矿粉无熟料固结体力学性能

为了探究超细铁尾矿粉颗粒表面非晶态SiO_(2)和Al_(2)O_(3)在石灰-石膏体系中的水化固化机理及调控因素,本工作考察了石膏掺量和铁尾矿粉中微纳米级颗粒含量之间的匹配对固结体强度的影响,利用XRD、TG-DSC、SEM和化学滴定法测试分析了固结体试样中水化产物的种类、形貌及含量的变化,研究了这些变化对固结体强度的影响及作用机理。结果表明,超细铁尾矿粉中小于1.096μm的微纳米颗粒含量显著影响着铁尾矿粉在碱溶液中Si和Al元素的溶出行为,固结体强度随着这些微纳米颗粒含量的增加而提高。固结体中的主要水化产物是铝掺杂的水化硅酸钙(C-(A)-S-H)和钙矾石(AFt)。石膏掺量与铁尾矿粉中微纳米颗粒含量的最佳匹配值对固结体的强度具有显著影响,并且微纳米颗粒含量越高,对应的石膏最佳掺量越大。石膏组分保证了AFt的生成和稳定,同时也加速了铁尾矿粉颗粒表面非晶态成分的水化。本工作探明了固结材料中最佳石膏掺量与微纳米铁尾矿粉颗粒含量的关联关系及其机理,证实了微纳米级颗粒是无熟料固结体结构中的基本活性单元,石膏的掺入对微纳米颗粒的水化起到调控作用,水化后的微纳米颗粒演变为固结体的基本结构单元,这种组分和结构的“双基因”调控机制影响着固结体的力学性能。

缓倾斜厚大矿体机械化垂直分条上向分层干式充填采矿方法研究

当采用传统的上向分层干式充填采矿法开采缓倾斜厚大矿体时,常常面临着机械化程度低、矿石贫损率高等问题。针对此问题,提出了一种缓倾斜厚大矿体机械化垂直分条上向分层干式充填采矿法。其核心是将矿体沿走向方向上划分为若干分条,采用上向分层干式充填采矿法逐条回采,并在矿房一侧留设废石混凝土挡墙,随后在充填体上铺设耐磨钢板,且配备铲运机等机械化设备进行出矿和充填,从而提高机械化程度,降低矿石贫损率。首先,介绍了缓倾斜厚大矿体机械化垂直分条上向分层干式充填采矿法的采场布置方式、回采工作、充填工艺,并阐述了其技术优势。其次,以某地下金矿为例,将该方法与上向分层尾砂胶结充填采矿法进行了经济比较。研究表明:当采用该方法回采矿体时,每个采场可多获得收益105万元。研究成果可为类似矿山条件下缓倾斜厚大稀有贵重金属矿体安全高效回采提供技术指导。