Rocket-based combined-cycle (RBCC) powered vehicles have been widely recognized as the most promising aircraft solution that could dramatically reduce the cost of space transportation. Researchers and scientists worldwide have conducted considerable overall design researches to cope with the challenges in RBCC development including mode transition, thermal protection and thrust enhancement. According

The dual-drive feed mechanism (DDFM) based on the drive at the center of gravity (DCG) principle has been widely adopted in computer numerical control (CNC) machines and industrial robots that require high precision and high stability. The friction force affected by feed rates and moving parts positions can change the contact stiffness of kinematic joints, which can further impact on dynamic characteristics

Periodic elastic waveguides, such as rods, beams, and shafts, exhibit frequency bands where wave reflections at impedance discontinuities cause strong wave attenuation by Bragg scattering. Such frequency bands are known as stop bands or band gaps. This work presents a shape optimization technique for one-dimensional periodic structures. The proposed approach, which aims to maximize the width of the

A six degrees-of-freedom parallel platform in a 6-RR-RP-RR configuration with high accuracy, high stiffness and a large working stroke is studied for application to the sub-mirror adjustment system of a large-aperture telescope. To meet the performance requirements, the parallel platform adopts a self-centering and well-designed offset universal hinge. The two hinge axes of the offset hinge do not

The axial location of full-span boundary layer suction is studied to explore the influences of suction slot on the cascade performance. At the design condition, the slot with 50% axial location shows a superior capability to reduce the total pressure loss. At the near stall condition, the more upstream of the suction slot is moved, the more total pressure loss is reduced, and the suction slot with

The poor real-time performance and target occlusion occurred easily when the UAV was tracking the target. In this paper, a target tracking method based on the Back Propagation neural network fusion Kalman filter algorithm was developed to solve the position prediction problem of the UAV target tracking in real time. Firstly, the target tracking algorithm was used to acquire the center position coordinates

In this study, methods to mitigate anomalous wave propagation in 2-D Bond-Based Peridynamics (PD) are presented. Similarly to what happens in classical non-local models, an irregular wave transmission phenomenon occurs at high frequencies. This feature of the dynamic performance of PD, limits its potential applications. A minimization method based on the weighted residual point collocation is introduced

The object of this fundamental research will be to reveal the effects of variable coefficient of static friction on the static behavior of disc spring. On account of the complex relationship between friction and normal pressure, based on contact mechanics and fractal theory, a model for predicting variable coefficient of static friction of 3 D fractal surface is induced. Then the method proposed by

The objective of this paper is to numerically study the heat transfer and hydrodynamic performance of a graphene-based hybrid nanofluid flowing through a microchannel for electronics cooling applications. Different concentrations of Graphene-Platinum/water hybrid nanofluid were employed as coolants. The thermophysical properties used in this study were considered to be temperature-dependent. The microchannel

Aiming at some shortcomings of the existing non-contact two-dimensional high-precision measurement methods, this paper proposes a two-dimensional high-precision non-contact automatic measurement method based on the corner coordinates of the image. Firstly, this paper designs a set of simple image acquisition device and explains the advantages of the Canny operator used in the image contour detection

Functionally graded material (FGM) has an important application prospect in aircraft engineering, especially in smart aircraft. The dynamic behavior of FGM has been widely investigated so far but more work is needed for the porous FGM pipes conveying fluid. In this paper, a sensible pore distribution function related with the volume fraction of metal and ceramic is proposed for the dynamic modeling

Humanoid robotic hand actuated by shape memory alloy (SMA) represents a new emerging technology. SMA has a wide range of potential applications in many different fields, ranging from industrial assembly to biomedicine applications, due to the characteristic of high power-to-weight ratio, low driving voltages and noiselessness. However, nonlinearities of SMA and complex dynamic models of SMA-based robotic

In this paper, a manipulator of the bionic mantis robot is designed inspired by the anatomical structure of the mantis front leg. A geometrical method is utilized to calculate the forward kinemics. Then, by analyzing the mantis motion video frame by frame, each of the front leg joints angles is measured in crawling and preying motion, which are used as interpolation conditions to solve the planned

Wind turbine blade is the key component to capture wind power, and it is mainly composed of glass fiber reinforced polymer (GFRP). Due to the randomness and volatility of wind speed in nature, wind turbine blade is usually subjected to the alternate action of normal and extreme wind loads during its long-term service. In this study, a reliability model that considering the stochastic wind loads and

The combination of sliding/rolling motion can influence the degree of precision degradation of ball screw. Precision degradation modeling and factors analysis can reveal the evolution law of ball screw precision. This paper presents a precision degradation model for factors analysis influencing precision due to mixed sliding-rolling motion. The precision loss model was verified through the comparison

High precision, efficiency and reliability are the unremitting pursuits of machinery manufacturing industry. As one of the pivotal function parts of high-end NC machine tool, precise linear guideway determines the machining precision and operation performance. Accurate evaluation and prediction of surface topography are the crucial effects on the matching performance of linear guideway. In this paper

In the present work, a novel hybrid finishing process that combines the two preferred methods in industries, namely, chemical-mechanical polishing (CMP) and magneto-rheological finishing (MRF), has been used to polish monocrystalline silicon wafers. The experiments were carried out on an indigenously developed double-disc chemical assisted magnetorheological finishing (DDCAMRF) experimental setup.

Engineering field nurtures a variety of superalloys and its wide applications due to the inherent properties of such material. The prime concern of working engineers is to explore reliability, quality, economy, and machinability analysis of these superalloys. In this work, sustainable machining of Monel 400superalloy using PVD multilayer coated carbide tool under dry turning was studied. Surface roughness

This paper deals with Marangoni convective flow of Carreau fluid. Boundary condition for momentum equation is considered to be Marangoni type. Thermal energy produces when current passes through the electrical conductor and this process is called Joule heating. Viscous dissipation is also applied in thermal equation. Nonlinear mixed convection for temperature is considered. Governing equations of PDE's

Combining wheeled structure with hopping mechanism, this paper purposes a self-balanced hopping robot with hybrid motion pattern. The main actuator which is the cylindrical cam, optimized by particle swarm optimization (PSO), is equipped with the motor to control the hopping motion. Robotic system dynamics model is established and solved by Lagrangian method. After linearization, control characteristics

Theory of Critical Distances (TCD) collects several methods adopted in failure prediction of components provided with stress concentration features. The idea of evaluating stress effect in a zone rather than in a single point was proposed decades ago but, only thanks to relatively recent works, TCD concepts showed to be a successful extension of Linear Elastic Fracture Mechanics (LEFM), able to assess

Primary focus of the current investigation is to analyze the effect of friction stir processing upon AlCoCrCuFe addition on Copper metal-metal surface composites. Copper surface composite along with the prepared novel AlCoCrCuFe high-entropy alloy (HEA) formulated through arc melting technique as reinforcement material is developed in the course following Friction Stir Processing (FSP) technique. Effect

This paper presents a new approach to predict the residual stresses caused by welding in a butt-welded specimen. Based on the developed three-dimensional finite element model, both the process of material filling and the effects of phase transformation are considered through the material properties which depend on both the temperature and temperature history. For simulating the change in volume caused

The classical method to find possible solutions for path synthesis problem of planar mechanisms is continuation method. However, this method has some disadvantages such as producing unwanted extraneous and degenerate solutions and also producing mechanisms having defects. Moreover, many of the solutions are cognate of each other which can be obtained geometrically. Thus, finding the most feasible solution

The noise transmission of aeronautical panels is an important phase of the design process of an airplane. In this work an analytical Navier-type solution, based on higher-order layer-wise shell models, is proposed for the analysis of the sound insulation of laminated panels. The considered multilayered structures are laminated with cross-ply composite layers embedded with interlaminar viscoelastic

This paper is intended to study the dynamic oscillatory behavior of chloride ion inside electrically charged open carbon nanocones (CNCs) using the molecular dynamics (MD) simulations. The small and wide ends of nanocone are assumed to be identically and uniformly charged with positive electric charges. In the simulation, the Tersoff-Brenner (TB) and the Lennard-Jones (LJ) potential functions are employed

Fuzzy logic is widely known as a value-based technique. Whale optimization algorithm (WOA), on the other hand, is a nature-inspired optimization technique. Hybridization of these two techniques is proposed for path planning and control, over multiple mobile robots in static and dynamic environments. The effectiveness of the resulting technique, known as ‘Fuzzy-WOA’, is tested through MATLAB simulation

Heat and mass transfer in a viscous flow over a non-uniform porous plate of variable thickness is investigated in this paper. The variably heated plate is stretched/shrunk in a stagnant fluid with variable velocity and has the non-uniform species concentration. The governing partial differential equations are simplified and solved numerically. The transport of heat and mass in the flow regime is governed

Manufacturing errors widely exist in and deteriorate the dynamic property of planetary gear train (PGT). To solve this problem, the ring gear is often designed with a thin rim to compensate for the effects of manufacturing errors via the elastic deflections of the rim. Existing dynamic models of the PGT only consider the effects of either the elasticity of the rim of the ring gear or the manufacturing

In this paper, modeling impact dynamics of a piston and its cylinder body in a hydraulic cylinder is investigated. The studied system consists of two identical hydraulic cylinders controlled by a pressure sequence valve. The impact is assumed as a linear one dimensional and purely translational viscoelastic impact of rigid bodies. Four impact models, the Kelvin-Voigt, the Maxwell, the standard-solid

In this study, the effect of rim thickness of hybrid gears on the root stress, joint stress, tooth stiffness, natural frequency, and dynamic behavior are examined numerically. Hybrid gears consist of two materials, which are steel for the teeth-rim and hub regions of gear, carbon fiber reinforced plastic (CFRP) for the web region. Adhesive bonding is assumed for the joining of steel and composite materials

Hysteretic damping of a material or structure loaded within its elastic region is the dissipation of mechanical energy at a rate independent of the frequency of vibration while at the same time directly proportional to the square of the displacement. Generally, reproducing this frequency-independent damping can be computationally complex and requires prior knowledge of the system’s natural frequencies

False (artificial) diffusion provides an erroneous estimation of molecular diffusion during the simulation of liquid micromixing. The present review introduces discretization methods, numerical grid types, and numerical errors to address the effect of false diffusion on the prediction of mixing efficiency of microfluidic devices. False diffusivity is characterized by the grid Peclet number, grid type

Because of the advantages of light weight, small size, and good maneuverability, the bio-inspired micro aerial vehicle has a wide range of application prospects and development potential in military and civil areas, and has become one of the research hotspots in the future aviation field. The beetle’s elytra possess high strength and provide the protection of the abdomen while being functional to guarantee

Contact of balls in screw nuts and bearings causes the nonlinearity of a ball screw feed system. The identification of nonlinear stiffness helps to understand and control the feed system. The axial vibration of the ball screw feed system can be descripted by a single-degree-of-freedom (SDOF) system with polynomial nonlinear terms. Since generalized frequency response functions (GFRFs) can be expressed

The number of synthesized kinematic chains usually is too large to evaluate individual characteristics of each chain. The concept of connectivity is useful to classify the kinematic chains. In this paper, an algorithm is developed to automatically compute the connectivity matrix in planar kinematic chains. The main work is to compute two intermediate parameters, namely the minimum mobility matrix and

Multi-unit serial mobile robot designed for obstacle avoidance, inspection or rescue task, should ideally be able to switch the head and tail as supporting stand to move forward wriggly, be lightweight and low energy consumption, aiming at adapting to complex application environment. This paper proposes a novel robot pitching unit based on a parallelogram mechanism, and a robot with the proposed units

The cold box, which comprises of several plate-fin heat exchangers (PFHE), is largely utilized in different industries. In this research, the computational fluid dynamics (CFD) technique has been used for investigating the impact of different fluid distributors on the rates of heat and mass transfer, in an industrial complex cold box equipped with plate-fins. While inlet and outlet fluid distributors

In this paper, the water droplet erosion (WDE) characteristics of four blade materials under different high-speed liquid-solid impingement conditions are tested with the experimental steps and data processing methods in ASTM-G73. On the basis of cumulative erosion curves, the maximum erosion rate (ERmax) is obtained to analyze the WDE resistance of the testing materials quantitatively. The effects

Thanks to their favorable strength-to-weight ratio, Aluminum-Zinc alloys are often used in high-performance industrial sectors. These alloys are characterized by poor erosion resistance, which could be increased by the deposition of thin films. For example, PVD (Physical Vapor Deposition) films can reduce wear and ensure appreciable performance in aggressive environments. This paper describes the effects

Comprehensive research has been carried out to investigate the effect of electrical conductivity (ĸ) of dielectric along with other process parameters in wire electrical discharge machining (WEDM) of Al 7075 alloy. Taguchi based design using L9 orthogonal array has been used to analyse the effect of open circuit voltage (VOC), pulse on time (TON), pulse frequency (fP) and servo sensitivity (SC) on

The article presents a new design solution for hydraulic gerotor machines. The main focus has been placed on the strain analysis of the behavior of a cycloidal gear set made of plastic. The gears comprise the main work unit of hydraulic gerotor machines, which are powered by driving the gear set. In state of the art, the rotational motion of the gear set was effected by driving the inner gear. This

The objective of current research is to analyze the MHD flow of a Maxwell fluid towards a stretching sheet with thermophoretic and stratification effects. The analysis of heat and mass transfer is presented in the presence of variable thermal conductivity and the Cattaneo-Christov theory. The Cattaneo-Christov theory is used instead of Fourier and Fick laws because Fourier and Fick's laws give parabolic

Electromechanical impedance (EMI) method has been widely used to evaluate structural health in recent years. In this method inexpensive, small, easy to apply, lightweight piezoelectric sensors are used to observe the changes in the structures. Different environmental conditions affect the piezoelectric sensor and the structure significantly. If the environmental impact is neglected, it causes misinterpretations

Fine finishing of spur gears reduces the vibrations and noise and upsurges the service life of two mating gears. A new magnetorheological gear profile finishing (MRGPF) process is utilized for the fine finishing of spur gear teeth profile surfaces. In the present study, the development of a theoretical mathematical model for the prediction of change in surface roughness during the MRGPF process is

In this paper, a new direct vertex-centred finite volume method (CV-FEM) has been developed for the thermoelastic problem in functional graded material (FGM) based on Lord-Shulman theory. The heat conduction equation in Lord-Shulman theory is modified by considering the product term of spatial gradient of relaxation time and the heat flux rate, and it makes the present method more accurate to capture

In this paper, we investigate the challenges of controlling the ARAS-Diamond robot for robotic-assisted eye surgery. To eliminate the system’s inherent uncertainty effects on its performance, a cascade architecture control structure is proposed in this paper. For the inner loop of this structure, two different robust controls, namely, H∞ and μ-synthesis, with stability and performance analysis, are

Trolling mode atomic force microscopy (TR-AFM) can considerably reduce the liquid-resonator interaction forces, and hence, has overcome many imaging problems in liquid environments. This mode increases the quality factor (QF) significantly compared with the conventional AFM operation in liquid; therefore, the duration to reach the steady-state periodic motion of the oscillating probe is relatively

In this paper, a novel adaptive funnel fast nonsingular terminal sliding mode control for robotic manipulators with dynamic uncertainties is proposed. A modified funnel variable is utilized to transform the tracking error fall within funnel boundary, which improves the transient and steady-state tracking performance of robotic manipulators. Based on the transformed error, a novel funnel fast nonsingular

In this paper, the particle swarm optimization algorithm is used to address the non-central symmetry cam profile problem of rotary dobby modulator. Four types of classical curves are used as the motion characteristics of the heald frame, and then the non-central symmetry cam profile of each curve is obtained. The particle swarm optimization algorithm is used to optimize and reconstruct these cam profiles

Horizontal platform systems are mechanical systems that can exhibit both periodic and chaotic behaviour. Various control techniques have been developed to solve their chaos synchronization. However, the avoidance of control saturation is rarely considered in existing control techniques. In this paper, a model predictive controller is developed to address the input-constrained chaos synchronization

In this paper, a new tooth modification method considering the contact ratio of gears and a new method for calculating the mesh-in impact force of modified helical gears are proposed. The new method for calculating the mesh-in impact force is based on tooth contact analysis and loaded tooth contact analysis. The mesh-in impact position can be calculated accurately via the new method. First, the procedures

Solar cooling technologies can play a vital role in renewable energy applications development. Thermoelectric systems have shown promising advantages over traditional refrigeration systems such as high thermal comfort, active adaptability, no moving parts, and refrigerants free. In this work, a novel thermoelectric air-conditioning system (TEACS) driven by photovoltaics (PV) is experimentally and theoretically

In this paper, the singularity of a planar mechanism with kinematic redundancy is studied. First, the architecture of the mechanism and the concept schematic diagram for singularity avoidance are stated. Next, inverse kinematics model of the planar parallel mechanism with kinematic redundancy is established. For determining the unique inverse solution of the mechanism under certain initial installation

Operational modal analysis (OMA) is a procedure that allows the modal parameters of a structure to be extracted from the measured response to an unknown excitation generated during operation. Nonlinearity is inevitably and frequently encountered in OMA. The problem: The traditional OMA method based on linear modal theory cannot be applied to a nonlinear oscillation system. The solution: This paper

The electro-hydraulic system is widely used in industrial production due to its high power-to-weight ratio, but the heavy-duty characteristics make the electro-hydraulic system subject to large disturbance force even if the actuator moves slightly, especially in mobile machines and multi-actuators system. Therefore, a position and velocity constraints method based on barrier Lyapunov function is proposed

Machining is material removal from a workpiece. Current spindle technologies allow the material to be removed very quickly but unfortunately this compromises the accuracy of the desired machined trajectory on the workpiece. Proposed solution to the problem is restricting motion of the tool and giving rotation to the workpiece. This paper presents analysis of the accuracy of trajectory of material removal

The coupled heave and pitch motions of a ship sailing in head waves affect the stability of the marine rotor-bearing system. Based on the theory of analytical mechanics, this study establishes a dynamic model of the rotor-bearing system subjected to the coupled motions of heave and pitch, considering nonlinear oil film moments produced by the tilting of the rotor in the bearings. The nonlinear dynamic

In this paper, based on the parametric design of 3 D blades including typical cross-section and natural frequency calculation of the equivalent model, an integral method for aerodynamic performance and aeroelastic vibration analysis of blade with Gurney flap is proposed. Parametric design and unstructured grid are used to pre-process the blades with/without the Gurney flap. The discrete aerodynamic

In laser-assisted machining (LAM), the laser source is focused on the workpiece as a thermal source and locally increases the workpiece temperature and makes the material soft ahead of the cutting tool so using this method, the machining forces are reduced, which causes improving the surface quality and cutting tool life. Machinability of advanced hard materials is significantly low and conventional