Existing studies of the structural strength of longwall mining hydraulic support are mainly focused on the force acting on individual supports instead of the general mechanical characteristics of the support group in a fully mechanized coal seam working face. This study combines theoretical analyses and experiments to investigate the mechanical characteristics of a longwall mining hydraulic support

A new nonlinear rotor model supported by the rolling bearing is established under the consideration of the bearing with waviness fault, the unbalanced excitation, the nonlinear Hertz contact force, the varying compliance vibration, and, especially, the physical nonlinear stiffness of the shaft material. The expression with cubic nonlinear terms is adopted to characterize the physical nonlinear stiffness

According to the characteristics of the constant deceleration braking system of hoist, a variable step-size fruit fly optimization algorithm–complex Gaussian wavelet support vector data description method is proposed in this article to evaluate the performance of the brake system. This method takes the pressure–time curve of safety braking as the characteristic data and extracts the candidate characteristic

Multiaxial fatigue of the components is a very complex behavior. This analyzes the multiaxial fatigue failure mechanism, reviews and compares the advantages and disadvantages of the classic model. The fatigue failure mechanism and fatigue life under multiaxial loading are derived through theoretical analysis and formulas, and finally verified with the results of multiaxial fatigue tests. The model

To improve the intershaft seal performance of the dual-rotor turbofan engine and extend the life of the intershaft seal, a compliant cylindrical aerodynamic intershaft seal structure is proposed, which avoids the problem of leakage increase after tooth wear of intershaft labyrinth seal. According to the proposed seal structure, the force condition of the floating seal ring is analyzed, and an aeroelastic

Electrical agglomeration as a pretreatment means can reduce the exhaust particle number concentration of diesel engine. The charge of particle is an important factor affecting the coagulation process. Therefore, an experiment was carried out to study the charging characteristic of diesel particles. Zeta potential for diesel particle was used to represent the charged state and the charge of particles

The spray formation and breakup process in an open-end swirl injector were studied through experiments and numerical simulations. A high-speed shadowgraph system and a high-speed backlight system were adopted to record the spray. Volume of fluid was used as the interface tracking method to capture the evolution process. The filling process of the liquid film inside the injector was captured. The air

Introduction: As an important transportation, the research on the control strategy of forklift has not been widely carried out. Objectives: This article proposes a turning slip regulation control strategy, which includes the improved electronic differential velocity control and turning slip regulation control, to track the optimal slip ratio. Methods: First, combined with the basic structure and characteristics

The lightweight of axle hub has been recognized as a typical representative of reducing the quality of vehicles for energy saving and emission reduction. Therefore, a modeling analysis and lightweight design based on ANSYS for axle hub is proposed. Firstly, design dimensions and structural parameters of axle hub are modeled. The hub model is imported into workbench software to simulate the static analysis

Ocean acidification is a global issue with particular regional significance in the California Current System, where social, economic, and ecological impacts are already occurring. Although ocean acidification is a concern that unifies the entire West Coast region, managing for this phenomenon at a regional scale is complex and further complicated by the large scale and dynamic nature of the region

To improve the reliability and accuracy of dynamic machine in design process, high precision and efficiency of numerical computation is essential means to identify dynamic characteristics of mechanical system. In this paper, a new computation approach is introduced to improve accuracy and efficiency of computation for coupling vibrating system. The proposed method is a combination of piecewise constant

The study of water entry cavity and the analysis of load characteristics are hot topics in water entry research. The coupled Euler–Lagrange method is used to carry out simulation research on the water entry process of a cylinder. Aiming at the water vapor mixing phenomenon caused by structure slamming on the water at the initial time of water entry, the slamming load is further studied by correcting

In order to study the characteristics of a rolling lobe air spring, a vertical stiffness analytical model is constructed based on thermodynamics and hydrodynamics. The merit of this vertical stiffness analytical model is that an analytical solution of geometric parameters is obtained by an approximate analytic method. Meanwhile, experimental tests are carried out to verify the accuracy of the vertical

A negative stiffness mechanism consisting of a spring and cylinder is proposed, and a grounded dynamic vibration absorber is designed based on a quasi-zero stiffness vibration isolator to constitute the vibration isolator with a vibration absorber system. The range of parameters for attaining zero stiffness is derived from static analysis. The dynamic analysis of the vibration isolator with a vibration

A highly integrated electromechanical actuator was developed in this article, which aims at fulfilling the requirements of high power-to-weight ratio, high efficiency, high integration and low volume in military equipment. Three different transmission schemes were proposed for the integrated electromechanical actuator according to the differences in integration methods. Comparative analysis was conducted

This study explores the effects of the thermal stress, rotation, and magnetic fields on the propagation of surface waves in a symmetric five-layered inhomogeneous elastic plate. The harmonic wave solution was adopted to reduce the given partial differential equations to their corresponding ordinary differential equations, which were later solved using a classical method. The Mathematica software was

A numerical and experimental study was carried out to investigate the two-phase flow fields of the typical three valves used in the multiphase pumps. Under the gas volume fraction conditions in the range of 0%–100%, the three-dimensional steady and dynamic two-phase flow characteristics, pressure drops, and their multipliers of the ball valve, cone valve, and disk valve were studied, respectively,

The aim of this article mainly lies in two aspects. The first is to investigate the effect of inlet swirl distortion on the performance and stability of a low-speed compressor experimentally. The second is to quantify swirl pattern revolution through the compressor and find out background causes of the change in compressor performance. Swirl distortion makes the leading-edge incidence opposite between

The variable stiffness joint is a kind of flexible actuator with variable stiffness characteristics suitable for physical human–robot interaction applications. In the existing variable stiffness joints, the antagonistic variable stiffness joint has the advantages of simple implementation of variable stiffness mechanism and easy modular design of the nonlinear elastic element. The variable stiffness

Compared with four-stroke engines, single-cylinder two-stroke engines have the characteristics of small inertia, high rotational speed, and wide excitation frequency range. However, the structural vibration and noise generated by the two-stroke engine are very violent. Hence, it is necessary to reduce the vibration and noise of the single-cylinder two-stroke engine. Based on the design theory of the

Due to the enormous energy densities of liquid hydrocarbon fuels for future utilization on micro scale, there is a concern about the feasibility of scaling down reciprocating internal combustion engines from small scale to meso scale. By building a specialized test bench, the performance and combustion characteristics of a miniature internal combustion engine with a displacement of 0.99 cc were tested

Obstacle distance measurement is one of the key technologies for cable inspection robots on high-voltage transmission lines. This article develops a novel method based on binocular vision for extracting the feature points of images and reconstructing 3D scenes. The proposed method seamlessly incorporates camera calibration, dense stereo matching, and 3D reconstruction. We apply a novel calibration

Prior safety evaluations of interchange merging areas have mostly focused on traffic conflicts and operating speeds, without considering how these factors can influence the driver workload. Researches regarding the level of driver workload have largely concentrated on urban roads, tunnel sections, and basic freeway segments, without considering the impact of merging traffic flows on safety. Therefore

Due to imperfect design norms and guidelines for China’s truck escape ramp, previous studies have not been able to reflect the effect of wheel subsidence process on the deceleration of runaway vehicles. A discrete element method was used to establish an aggregate discrete element and a wheel discrete element. The three-dimensional discrete element model for an aggregate-wheel combination was established

Corrigendum to The Haze Extreme Co-movements in Beijing-Tianjin-Hebei Region and Its Extreme Dependence Pattern Recognitions. Sci Prog 103(2): 1–30. DOI: 10.1177/0036850420916315

To find the optimal one from all feasible module configuration schemes of high-end computer numerical control machine tools according to performance, cost, and delivery, this article studies the method of module configuration optimization. An ideal outranking cardinal point based on the module configuration optimization approach of vertical computer numerical control honing machine is proposed in this

Dynamic forces are very important boundary conditions in practical engineering applications, such as structural strength analysis, health monitoring and fault diagnosis, and vibration isolation. Moreover, there are many applications in which we have found it very difficult to directly obtain the expected dynamic load which acts on a structure. Some traditional indirect inverse analysis techniques are

Accurate and real-time position of preview point is significant to trajectory tracking control of vision-guided intelligent vehicle. The unavoidable delay of road automatic identification system weakens trajectory tracking control performance, and even deteriorates the vehicle stability. Therefore, a compensator for the delay of road automatic identification system was proposed which combines the current

Topology optimization is a widely used lightweight design method for structural design of the collaborative robot. In this article, a topology optimization method for the robot lightweight design is proposed based on finite element analysis of the assembly so as to get the minimized weight and to avoid the stress analysis distortion phenomenon that compared the conventional topology optimization method

The surrounding rock may become unstable or even fall down and the initial support may crack and be destroyed when the construction method of the underground excavation tunnel is not properly selected in the turn line of metro. . A section of the Santunbei turn line of Urumqi Metro Line 1# was taken as the engineering background. The proposed construction method was analyzed by numerical simulation

In rape combine harvester, side cutter must be equipped to cut off tangled rapeseed twigs. Inappropriate cutting speed would increase the repeated cutting and missing cutting of side cutter, which lead to serious header loss. In allusion to the problems mentioned above, bidirectional electric drive side cutter and a cutting speed follow-up adjusting system were proposed. The kinematic law of side cutter

Polycrystalline diamond compact bits have been widely used in the Oil and Gas drilling industry, despite the fact that they may introduce undesired vibration into the drilling process, for example, stick-slip and bit bounce, which accelerate the failure rate and lead to higher drilling costs. First, we develop an innovative ridge-ladder-shaped polycrystalline diamond compact cutter, which has ridge-shaped

The hydraulic structure of conventional geophysical drill bit is designed for the general stratum. When conventional geophysical drill bit pierces into a limestone stratum, the shape of cuttings is large because of the high brittleness of limestone. The cuttings are ground repeatedly; this phenomenon can reduce drilling efficiency and increase drilling costs. According to the characteristics of limestone

In order to accurately improve and predict chatter stability region of machining process, an optimization method of machining process with non-uniform allowance of integral impeller was proposed. The modal parameters of the workpiece process system were obtained using the finite element analysis. Based on the regenerative chatter analysis theory, a limit comparison diagram of the stability with uniform

Floor stress distribution is the main index for evaluating the mining effect of upper protective coal seam. However, parameters currently used in theoretical analysis of mining-induced stress lack practicality. Therefore, in this article, a model for calculating floor stress during mining of upper protective coal seams was established based on the theory of elastic mechanics. Subsequently, the stress

The structural design of vehicles plays an important role in improving vehicle safety and driving performance. In this study, the frame structure of a van-type electric truck was taken as a research object. Stress, strain, and modal analyses of this frame structure were performed using Abaqus, a finite element software, to verify the rationality and safety of the structural design. The frame structure

Shear key joints are commonly used in constructions of precast concrete segmental bridges. Most researches focused on shear performance of the dry joints with the identical-strength concrete, leaving a research gap on that of composite joints between different concrete segments. This research aims to investigate shear behavior of shear key joint between reactive powder concrete and high strength concrete

Jet dispenser is widely used in microelectronic packaging, semiconductor industry, life science, and rapid manufacturing fields. As the requirement for dispensing accuracy and speed become higher and higher, especially for viscous materials, the traditional mechanisms cannot meet the high precision dispensing. This paper presents a new jetting dispenser using the complaint mechanism with amplifier

With the development of pipeline construction, the additional stress and strain becomes the key factor to induce the damage for oil and gas pipeline. The in-line inspection of pipeline bending strain which is based on high-end tactical-grade inertial measurement unit has become routine practice for the oil and gas pipelines over recent years. However, these accurate inertial measurement units are large

In this paper, a full-scale model of Low Vibration Track was established and three working conditions were applied to a single bearing block; these include: vertical load at the end of the track slab, combination of horizontal and vertical load at the end of the track slab, and vertical load at the middle of the track slab. By applying four times static wheel load to the full-scale model, the relationship

Based on Hertz contact theory, an elastic-plastic contact mechanics model of outer cylinder under different contact angles of axis is proposed. The relationship among contact angle, load and contact deformation, contact stiffness and contact area is established. The finite element method is used to simulate the elastic-plastic contact process of the cylinder. The influence of the load and radius of

Seasonal variations in the temperatures of the hemispheres induce seasonal energy cycles between the hemispheres that drive tropical cyclones. Because the northern hemisphere has warmed more than the southern hemisphere, climate energy cycles develop between the hemispheres as well. The seasonal and climate energy cycles appear to interact among themselves, and tropical cyclone counts are affected

To investigate the performance of engine cooling water pump in automobile with variable rotating speed, experimental tests and numerical simulation are carried out on an engine cooling water pump under the rotating speed of 2650, 2960, 3700, and 4300 r/min. The hydraulic performance under 3700 r/min rotating speed and the cavitation performance under 340 L/min flow rate are tested and analyzed. The

This article develops a rapid performance evaluation approach for lower mobility hybrid robot, which provides guidance for manipulator evaluation, design, and optimization. First, a general position vector model of gravity center for the lower mobility hybrid robot in the whole workspace is constructed based on a general inverse kinematic model. A performance evaluation index based on gravity-center

To solve the problems that the borehole depth is shallow and the drilling efficiency is low during the gas drainage drilling in soft coal seam with current cuttings removal method, a new technology of reverse circulation pneumatic cuttings removal is proposed. The working principle of reverse circulation pneumatic cuttings removal is analyzed, and the kinetic equation of cuttings in the inner hole

Symptomatic intracerebral hemorrhage is a serious potential complication of recombinant tissue-type plasminogen activator thrombolysis in acute ischemic stroke. We investigated the optimal imaging and clinical parameters to predict symptomatic intracerebral hemorrhage in acute ischemic stroke patients after recombinant tissue-type plasminogen activator therapy. We retrospectively reviewed 151 acute

Carbon fiber–reinforced carbon matrix composites have been widely used for the manufacturing of thermostructural parts for several industries such as the aerospace and automotive. Drilling is an extremely common method used in the machining of carbon fiber–reinforced carbon matrix composites before assembly. However, their non-homogeneous, anisotropic, and brittle nature make difficult to guarantee

Compression ignition engines are one of the world’s largest consumers of fossil oil but have energy extraction efficiency limited to 35%. Addition of hydrogen alongside diesel fuel has been found to improve engine performance and efficiency; however, after a certain limit, hydrogen begins to show adverse effects, mainly because the ratio of oxygen to fuel decreases. This can be overcome by using oxyhydrogen

Field studies by squeezing rock deformation have shown that large deformation slips can occurs in tunnels in squeezing rock, the tunnels may be partially or completely broken. This article proposed two schemes for controlling the deformation of squeezing rock, which are “resistance combine release” Scheme 1 and “strong support” Scheme 2, the deformation characteristics and deformation mechanism of

In order to take advantage of different forms of heat pumps and to mitigate thermal imbalance underground caused by long-term operation of ground source heat pumps, hybrid ground source heat pump systems have received an increasing attention. In this research, based on the fact that abundant groundwater resources are commonly available in karst regions, a new strategy is introduced for selecting and

Extreme haze was often observed at many locations in Beijing-Tianjin-Hebei region within several hours when they occurred, which is referred to as extreme co-movements and extreme dependence in statistics. This article applies tail quotient correlation coefficient to explore the temporal and spatial extreme dependence patterns of haze in this region. Hourly PM2.5 station-level data during 2014-2018

Considering the multiple effects of product greenness and carbon emission trading, this article constructs a differential game model to study the collaborative innovation between enterprises in a green supply chain composed of one manufacturer and one supplier. This article examines the optimal green technology innovation strategies, optimal revenues of manufacturers and suppliers as well as the overall

The fatality rate can be dramatically reduced with the help of emergency medical services. The purpose of this study was to establish a computational algorithm to predict the injury severity, so as to improve the timeliness, appropriateness, and efficacy of medical care provided. The computer simulations of full-frontal crashes with rigid wall were carried out using LS-DYNA and MADYMO under different

The research on the sealing problems is of great significance in the design of turbines and aircraft engines, with the constant pursuit of high thrust ratio and low fuel consumption. A large number of experimental studies give information that the brush seal not only has good sealing characteristics, high sealing efficiency, but also has low manufacturing cost and simple structure.1–6 The leakage of

The past decades have witnessed a great advance in studies of switched systems which are widely applied in robot systems,1 networked systems,2 chemical process3 and so on. Switched systems, which comprised multiple subsystems and a signal deciding to activate one of them, can effectively model processes or multiple-mode systems. Moreover, the idea of controller switching is carried over to many intelligent

Hydrodynamic effects of mussel farms have attracted increased research attentions in recent years. The understanding of the hydrodynamic impacts is essential for predicting the sustainability of mussel farms. A large mussel farm includes thousands of mussel droppers, and the combined drag on the mussel droppers is sufficient to possibly affect the longevity of the entire long-lines. This article intends

The purpose of this study was to evaluate the functional and cosmetic outcomes of a new modified Fox pentagon technique performed using polytetrafluoroethylene in frontalis suspension surgery for blepharophimosis syndrome. This retrospective study enrolled 40 patients diagnosed with blepharophimosis syndrome from March 2016 to October 2018. All patients underwent frontalis suspension using a new modified

Rotary lip seal is used in various applications where the rotation shaft needs to be sealed, such as hydraulic pumps, fuel pumps, camshafts, crankshafts, and so on. Many thermal elastohydrodynamic lubrication models of rotary lip seal have been introduced, and most of these models neglect the asperity contact. This article proposes a mixed thermal elastohydrodynamic lubrication model of rotary lip

In order to study the heat transfer characteristics between two rough surfaces of two contacting blocks with different bulk temperatures and sliding reciprocating motion, a two-dimensional heat transfer model was used to analyze the dimensionless average heat flux, considering thermal contact conductance. The results of a series simulations were presented, covering a wide range of operating parameters

The beam pumping unit is widely used in oil fields as an oil extraction machine. However, due to its structural characteristics and the changing conditions of underground reservoirs, there are many factors affecting the efficiency of the beam pumping unit. How to quickly and accurately reflect the inefficient factors, and whether the efficiency of the pumping unit is reasonable, it is an urgent problem