Abstract:To solve the problem that the electronic skin tactile sensor which can be used on the surface of complex three-dimensional carrier such as robots is difficult to have high flexibility and stretchability and pressure detection function, a new method of flexible and stretchable electronic skin pressure tactile sensor is proposed from the selection of materials, structural optimization and new manufacturing process. The novel AgNWs/PDMS composite material is used. The new "sandwich" sensor array structure based on a semi-circular and circular shaped conductive film electrode layer and an array of "porous PDMS" is proposed, which greatly improves the flexibility and stretchability of the tactile sensor. And a highly flexible and stretchable electronic skin pressure tactile sensor is produced. The results show that the electronic skin pressure tactile sensor has good flexibility and stretchability, and the elastic stretch rate of the sensor exceeds the elasticity of human skin by 30%, then it can cover the surface of complex three-dimensional carriers such as robots to measure the pressure and distribution under different load conditions. Also the novel tactile sensor has high linearity, sensitivity and small hysteresis error in both natural and stretching states. Therefore, the tactile sensor laid the foundation for the development of flexible and intelligent robots.

Abstract:As a new micro-machining technology, water-assisted laser machining (WaLM) has a broad development prospect. The invention and main technical contents of WaLM are summarized, the main research achievements in theoretical and experimental fields for each kind of WaLM technology are introduced in detail, and the technical differences and applied scopes of each WaLM technology are discussed in this paper. The WaLM technology has obvious advantages in solving the problems of precision loss and efficiency reduction caused by laser thermal damage. Various WaLM devices and combination technologies also provide the reference for solutions of engineering problems.

Abstract:To improve the quality of products in deep drawing process, the deep reinforcement learning method is used to optimize the blank holder force (BHF). A new BHF control model based on the integration of deep reinforcement learning and finite element simulation is proposed, and the BHF control strategy is optimized by combining the perception ability of deep neural network with the decision-making ability of reinforcement learning. The proposed control model uses the deep neural network to deal with huge state space and avoids the fitting of system dynamics. By utilizing a novel strategy network structure, the BHF control strategy is divided into global and local parts, and the control effect is improved. Meanwhile, the theoretical knowledge of BHF is used to initialize the replay experience, which improves the learning efficiency of deep reinforcement learning algorithm in BHF control tasks. Experiments show that the proposed BHF control model can optimize BHF control strategy more effectively than traditional deep reinforcement learning algorithm. The comprehensive performance of the proposed control model in three quality indicators (internal stress, thickness and material utilizing rate) is better than that of the traditional deep reinforcement learning algorithms.

Abstract:To investigate the effect of lapping machine geometric errors on flank face roughness of diamond cutting tools, a mathematic model of lapping machine geometric errors and surface profile of tool flank face is built. The error propagation of lapping machine is modeled based on the theory of multi-body system. And a quantified relationship between machine errors and roughness is established using the algorithm of spline filter. The influence principle of end face and radial errors of spindle and sway, and the straightness error of reciprocates on roughness are analyzed. The result shows that the influence proportion of spindle, sway and reciprocating geometric moving errors on roughness are 98.18%, 1.59% and 0.23% respectively, hence roughness of flank face is mainly affected by spindle end face and radial errors which offers a guidance to the design and manufacturing of lapping machine and optimization of lapping technics for diamond cutting tools.

Abstract:Aiming at improving the effectiveness for detecting the small pieces of metal foreign object detection (MFOD) scattered in large area of wireless charging system (WCS) of Electric Vehicle (EV), a method for analyzing the electromagnetic characteristics of MFOD coil is presented. The principle of MFOD based on the mistuned appearance of resonant circuits disturbed by metal foreign object (MFO) is introduced. The main factors of affecting the electromagnetic characteristics of MFOD coil are analyzed, and the general design scheme for MFOD coil is proposed as combination of several printed circuit board(PCB) type small coils by series-parallel connection. By the Maxwell simulation, the influences of MFO entering above the MFOD coil on the magnetic field of MFOD coil are analyzed, and the influences of parameters and structural type of MFOD coil on electromagnetic characteristics of MFOD coil are obtained. The simulation result verifies that the presented design scheme for MFOD coil can restrain the induced electric noise under the condition of WCS of EV. The method can be used to guide the design of MFOD coil in WCS of EV.

Abstract:Now the subjective evaluation methods used in vehicles equipped with dual clutch transmission for shift quality causes the discreteness of evaluation results and the simple objective evaluation method leads to the evaluation results being limited to the data and ignoring the subjective knowledge guidance. The shift quality evaluation index is determined from three dimensions of time, longitudinal acceleration and engine speed. Based on the hierarchical clustering method and expert knowledge, the shift quality evaluation system is scientifically established. According to the evaluation system, the subjective weight of the shift quality evaluation index is obtained by combining the Delphi method and the analytic hierarchy process. The objective weight of the shift quality evaluation index is calculated by the coefficient of variation method, and the combined weight is given based on the principle of optimal allocation. Then the method of determining the membership function based on data difference and fuzzy threshold is proposed. Finally, the fuzzy comprehensive evaluation model of shift quality is established. The data based on the data difference and the fuzzy threshold are proposed. The experimental data is used to verify the effectiveness of fuzzy comprehensive evaluation model and coefficient of variation method in shift quality evaluation, and the fuzzy comprehensive evaluation model is verified more efficiency and accuracy, relative to the simple objective evaluation method. Each index reveals shift quality by re-evaluation of the right size for the two shift quality importance which provides effective guidance for improving the shift quality of the vehicle.

Abstract:To better solve the problem of clutch engagement process caused by variability of the clutch engagement trajectory and the tracking deviation under uncertain factors such as system parameter perturbation and external load disturbance, the optimization and tracking control method of the clutch engagement trajectory are proposed. Taking the clutch engagement process in the heavy-duty reverse shifting of the loader V-type working condition as the research object, a quadratic performance index function combining the jerk and friction work is established. Under the non-stationary random term with parameterized expression in the disturbance matrix, the variable torque optimal trajectory under the time-varying optimal control law and weight coefficient adjustment is obtained by constructing the Hamiltonian function and solving the Riccati differential equation based on Pontryagin maximum principle. To improve the tracking accuracy of the optimal trajectory under perturbation of nonlinear characteristic actuator, the quality optimization problem of the engagement process is transformed into a single target problem of trajectory tracking. The controller designed by sliding mode control method with exponential approach law achieves accurate tracking with tracking error within 0.3%, and its stability analysis is carried out by Lyapunov theory. The numerical simulation results show that the control method achieves the minimization of the friction work under the condition that the clutch engagement impact is lower than the national standard. The control method proposed in the paper will be beneficial to improve the quality of the clutch engagement process and have theoretical engineering reference value for solving similar problems.

Abstract:A multivariate process fault diagnosis model is proposed based on convolutional neural network (CNN), aiming at extracting effective features from complex multivariate processes and improving fault diagnosis performance. First, the high-dimensional process signals are normalized and then converted into images. Second, a lightweight CNN network composing of multi-layer convolution filters and sub-sampling filters is convolved with images through multiple convolution kernels, using local connections and shared weights to remove noise and interference information to obtain the high-level abstract representations of process data. Finally, a Softmax layer is used in a supervised way to implement fault diagnosis. Tennessee Eastman Process is used to verify the effectiveness of proposed model and compare the performance between the proposed model with classical classifiers and deep neural networks. The results show that the fault diagnosis accuracy is improved by converting high-dimensional process signals into images. The t-SNE visualization analysis method is used to illustrate the powerful feature extraction ability of proposed model. The features extracted by the proposed model are sent to the traditional classifiers and the accuracy of fault identification is significantly improved, which further illustrates the benefit of effective feature extraction for improving the fault diagnosis accuracy and reliability. Compared to unsupervised learning, the proposed model with the guidance of label helps to extract more efficient, stable, and abstract feature representations.

Abstract:To improve the accuracy of repeated deployment and positioning of solar panel, a solar panel repeatable expandable mechanism was developed. The expandable mechanism adopts the principle of internal staggered transmission of tether to realize the synchronous and repeated deployment function of the secondary windsurfing board, and adopts two horizontal and vertical arrangements to adapt to different deployment conditions of the solar windsurfing board. Based on engineering reality, two factors, hinge gap and windsurfing flexibility, were introduced to establish a dynamic model of expandable solar windsurfing, and simulation and numerical analysis were performed. The analysis results show that the accuracy of the terminal pose of solar sails decreases with the increase of hinge clearance, while the flexibility directly leads to the error in the expansion of solar sails. However, when the two are coupled, the effect of clearance on the accuracy of terminal pose can be compensated. The developed prototype of the expandable mechanism was used to test the solar wing deployment performance and the accuracy of repeated deployment positioning. The experimental results verified rational design of the hinge joint clearance, and the coupling effect of the flexibility of windsurfing and hinge clearance can compensate for the windsurfing repeatedly deployed end position error. Reasonably matching the two factors within the allowable error range can make the hinge gap value have a larger desirable range, which is beneficial for improving the positioning accuracy of the mechanism.

Abstract:To obtain gear meshing surfaces with good contact characteristics, multi-point contact gears with ladder shape of teeth is proposed based on the principle of conjugate curves. Four-point contact gears with ladder shape of teeth is taken as an example to present the design of basic tooth profiles and tooth surface design of hob. Basic tooth profiles are divided into two sections, non-working profiles and working profiles containing convex part and concave part. A circular arc and a parabolic curve are adopted as working tooth profiles to generate the upper meshing surface and the lower meshing surface respectively. Non-working tooth profiles contain a transition profile and a dedendum profile. Two circular arcs are adopted for non-working profiles. According to basic tooth profiles and gear meshing theory, the equations of the hob’s working, transition and dedendum surfaces are derived and solved by a developed program. The exactitude solid model of the hob is set up. The hob was manufactured and applied for generating gears. The four-point contact gear drive with ladder shape of teeth is acquired and the gear box prototype was assembled. The contact pattern of the gear drive is detected. Results show that the gears satisfy the design requirement. The paper is an extension of the principle of conjugate curve. The research method is suitable for other multi-point contact gears with ladder shape of teeth.

Abstract:To improve the stability of the atmospheric inductively coupled plasma (ICP) torch, a demountable ICP torch whose dielectric tubes were located by a special part was designed, and its heat transfer and flow characteristics were studied. Through the simulation by COMSOL Multiphysics, it is found that the annular heating and fluid backflow are the main reasons for thermal damage and etching damage of the torch. Therefore, the service life of the torch can be effectively improved by using ceramics as the material of the central and middle dielectric tubes and adjusting the position of the induction coil. In addition, the jet morphology was monitored by a CCD camera. It is found that the overall length (L) and the half-width (W) of the jet linearly changes with the radio frequency power (P_w), the working gas flow (Q₂) and the cooling gas flow (Q₃). However, when the P_w, Q₂ and Q₃ are too big or small, the fluctuation of the jet increases, the ICP jet will become unstable. The results show that when P_w, Q₂ and Q₃ are set to 900-1 000 W, 650 mL·min^-1 and 16 L·min^-1 respectively, the demountable torch can generate stable ICP jet. The fluctuation of L and W can be controlled within 0.5 mm and 0.25 mm respectively, which is suitable for the processing of fused quartz and other optical surfaces.

Abstract:To achieve the development of glycerol as biodiesel byproduct in the industry of hydrogen production, the glycerol reforming process for hydrogen production in a membrane-assisted fluidized bed reactor is numerically simulated on the basis of the two-fluid model and the kinetic theory of granular flow coupled with the glycerol reforming kinetic model, where the CO₂ sorption kinetic model and hydrogen separation model are implemented. The gas component and particle concentrations as well as temperature are predicted, and the multiphase flow behaviors and reaction characteristics during the reforming process are evaluated. The mutual interaction mechanism of the two enhancing methods including membrane hydrogen separation and carbon dioxide sorption is discussed, and the impact of operating parameters on reforming performance is examined. The result reveals that the concentration polarization resistance will be restricted with the rising hydrogen permeation. At the sorbent to catalyst ratio of 1∶1, the relative hydrogen yield is improved by 5% compared to the reforming process without sorbents. When the membrane thickness is reduced from 300 μm to 30 μm, the CO₂ sorption rate can be increased by 1.4%. The utilization of catalyst-sorbent bi-functional particles can enhance CO₂ sorption and hydrogen separation. The hydrogen permeation is improved by almost 20%.

Abstract:To effectively describe the influence of factors such as the assembly personnel level and the workpiece quality on the job quality of aircraft assembly and establish a reasonable proactive schedule for the assembly process, a support vector regression (SVR) prediction model and a two-level iterative search algorithm are developed. Firstly, with collecting relevant historical quality data, a SVR prediction model is trained by taking the data of assembly personnel level, workpiece quality and so on as input and job quality as output. On the basis of the trained SVR prediction model, a job list-based tabu search framework is adopted to search the neighborhood of job list, and the optimization of personnel allocation is achieved through the serial scheduling generation scheme with embedded personnel assignment search module. The results of numerical experiments show that the predicted value of job quality obtained by the SVR prediction model can be controlled within 5% in comparison with the measured value, and the highest prediction accuracy is 97.38%. The mean deviation between the two-level iterative search algorithm and CPLEX is between 9.99% and 27.54%, which is the smallest among proactive scheduling generation methods. In the uncertain environment, the right shift algorithm can obtain the optimal or sub-optimal mean makespan and mean deviation in the baseline schedules obtained by the two-level iterative search algorithm. The SVR prediction model can effectively predict the job quality of aircraft assembly, and the two-level iterative search algorithm can meet the requirement of constructing proactive scheduling for aircraft assembly.

Abstract:Limited to the calculation capability of computers and computational cost, some physical assumptions for flows are needed in the realistic simulation, such as inviscid flow, incompressible flow and so on, which will take various degrees of error in the simulation results. To solve this problem, a numerical method used to solve the weak compressible viscous flow is presented here that is capable to solve the weak compressible viscous flow whether there is a static or moving solid body in the flow field. Starting from the state equation of water, the velocity and pressure governing equations for weak compressible viscous flows are derived rigorously. Considering the effect of solid body, the Boundary Data Immersion Method (BDIM), which can accurately represent moving bodies in flow and underwater acoustic simulations, is employed to couple the fluid sub-domain and solid sub-domain. Therefore, the flow field with the effects of the compression and viscosity is solved by coupling the weak compressible viscous flow and the BDIM. The effectiveness and accuracy of our method are validated by three two dimensional cases, and the results indicate that the novel method simulates the flow flied accurately and effectively for both a static and moving solid body.

Abstract:This paper first analyzes the influencing factors of free lane change of autonomous driving vehicle, and uses the traditional mathematical model to establish a vehicle lane change rule model based on the benefits, safety and necessity of lane change. Second, in view of the different factors considered in lane changing decision-making under different driving conditions, this paper proposes to extract decision variables from three aspects: physics-based features, interaction-aware features and road-structure-based features, and designs a feature extraction algorithm to make the factors considered in lane changing model decision-making more comprehensive. Then, for the multi-parameter and non-linearity problems existing in the decision-making process of autonomous lane change, a support vector machine (SVM) decision-making model based on Bayesian optimization algorithm (BOA) is proposed. Finally, the proposed model is verified on the NGSIM data set. The comparison test shows that the established BOA Gaussian-SVM model has a high comprehensive prediction performance, and the recognition rate of channel change behavior can reach 92.97%, which is better than other models and much higher than rule-based model. At the same time, simulation experiments are carried out on Airsim platform, and the results prove the effectiveness of BOA Gaussian-SVM decision model.

Abstract:To improve the operation stability and anti-interference ability of oil-gas two-phase hydrodynamic seal, the response motion of its sealing compensation ring was studied, and the following dynamic characteristics of oil-gas two-phase hydrodynamic seal were revealed. Considered the comprehensive effect of temperature and deformation on sealing ring and fluid film, a finite element analysis model of fluid-solid-thermal coupling between sealing ring and fluid film was established by using MATLAB software. The dynamic stiffness and damping coefficients of the fluid film were calculated, the forced vibration model of the oil-gas two-phase dynamic pressure seal was solved, and the response motion of the compensating ring was analyzed. The effects of rotational speed, differential pressure, oil-gas ratio, spring stiffness and O-ring damping on the angular and axial amplitudes of motion response of the seal compensation ring were discussed, and the following dynamic characteristics of the seal are analyzed. The results show that the following dynamic characteristics of the seal can be improved by increasing the rotational speed and the oil-gas ratio. The increase of pressure difference, spring stiffness and O-ring damping is not conducive to the follow-up response motion of the compensating ring, in which the response amplitude of the compensating ring is insensitive to the change of spring stiffness and O-ring damping in the early period of increase, and the response amplitude of the compensating ring decreases sharply in the later period of increase. The research results provide theoretical support for the optimization of compensation mechanism and dynamic performance research of oil-gas two-phase hydrodynamic seals, and a method of solving the following dynamic characteristics of oil-gas two-phase hydrodynamic seals based on fluid-solid-thermal coupling is obtained.

Abstract:To investigate the nonlinear viscoelastic response of E-glass fiber reinforced epoxy resin matrix composite, Schapery's model was used to describe the nonlinear viscoelasticity of composites, and the tensile creep/creep-recovery tests were carried out for [90]₁₆ transverse specimens and [±45]_4S shear specimens at different stress levels. According to the observed residual phenomena, a viscoplastic strain component was introduced into the Schapery's model and a method based on the analytical procedure for identifying the nonlinear viscoelastic parameters was proposed. The Schapery's nonlinear parameters g₀, g₁, g₂ and aσ were calculated, which are functions of the applied stress. The results show that the E-glass/epoxy composite exhibits obvious nonlinear viscoelasticity if the applied stress is higher than 53% of the tensile strength in transverse direction and 31% of the shear strength in the in-plan shear direction. In the transverse direction, the nonlinear parameters g_0T and g_2T are independent of stress, while g_1T increases linearly with stress, and a_σT decreases linearly with stress. In the in-plane shear direction, the nonlinear parameters g_0S and g_2S increase exponentially with stress, while g_1S increases linearly with stress, and a_σS decreases linearly with stress. Compared with the traditional nonlinear parameter identification method, the proposed method can obtain the relationship between nonlinear parameters and the applied stress conveniently and accurately.

Abstract:Considering the CFRP Flat-Joggle-Flat (FJF) adhesively bonded joint, the Bonded Beam element (BBe) of the curved segment was constructed, a semi-analytical model for adhesive stress analysis of such joint was proposed, and the stress results were compared with those of the 3D Finite Element Model (FEM). Meanwhile, the adhesive width and thickness were considered to study their effects on the adhesive stress. The results show that the distributions of adhesive peel stress and shear stress in semi-analytical model are basically in consistent with those in 3D FEM. The adhesive peel stress and shear stress at the end of overlap zone calculated in semi-analytical model has an absolute error value of 5.4% and 3.7% respectively compared with the corresponding stress calculated in 3D FEM. With the same adhesive width, both the adhesive peel stress and shear stress at the end of overlap zone appear to be smaller as the adhesive thickness increases. With the same adhesive thickness, both the adhesive peel stress and shear stress at the end of overlap zone appear to descend as the adhesive width increases. Moreover, both the adhesive peel stress and shear stress at the fillet of overlap zone descend with the increasing of adhesive width for the same adhesive thickness, while rising as the adhesive thickness increases for the same adhesive width. This model can offer some references for the mechanical analysis and design of the CFRP FJF adhesively bonded joints.

Abstract:To calculate the straightness error of the axis of hole accurately, an error evaluation method based on rotating projection was proposed. According to the homogeneous coordinate transformation and rotating projection, the measuring points are rotated to the same plane around the least square line. The spatial problem was transformed into a plane problem. Three control points were pre-selected in the plane point set. Considering the distance from control points and measurement points to the control line, the control points were continuously updated by using the distance ratio coefficient until the absolute value of the distance between the three control points and the control line was the largest. The three control points met the criteria of "high and low and high" or "low and high and low" in the minimum area. This method does not need complex nonlinear optimization process, and has small calculation amount and high accuracy of evaluation result. Rotating projection preserves the distance relationship between the measuring points, which avoids the problem of missing the control points combination in direct projection. The results show that the method has higher accuracy than other evaluation methods and takes less than 0.1s.

Abstract:degree rotating nozzle was introduced into water jet propulsion system. Based on the comprehensive analysis of the kinematic characteristics and amphibious environment adaptability of the existing amphibious robot, an amphibious vector water-jet driving device is designed by combining hollow driving wheel and axial-flow blade. Based on the momentum theorem and the theory of pressure and energy loss in the flow-path, the prediction of two-dimensional thrust and motor speed of amphibious water jet drive device was established. Based on the principle of energy conservation and viscous resistance moment, a prediction model of driving motor torque was established. CFD simulation of the device was carried out to obtain the flow characteristics such as pressure and velocity in the inner channel of the propeller. Finally, a wheel-pump combination amphibious thruster was made and tested under water. The thrust of the micro-wheel-pump combination amphibious thruster with a characteristic size of is 6.5 N at a speed of 2 800 r/min. The comparison error between the experimental results and the simulation results is less than 8%, which verifies the effectiveness of the configuration and the two-dimensional vector thrust characteristics.

Abstract:In this paper an implicit preconditioned gridless method is developed for solving Euler equations at low Mach numbers. The conservative preconditioned system is obtained by multiplying a preconditioning matrix of the type of Weiss and Smith to the time derivative of the three dimensional Euler equations, which are discretized under the clouds of points distributed in the computational domain by using a gridless technique. The implementations of the preconditioned gridless methods are mainly based on the frame of the traditional gridless method without preconditioning, therefore the modifications corresponding to the affect terms of preconditioning such as spectral radius, artificial dissipation and farfield boundary condition are first addressed in the paper. The lower-upper symmetric Gauss-Seidel(LU-SGS) algorithm is then introduced by reordering and splitting the cloud of points to form the implicit preconditioned gridless method. The proposed method is validated by simulating flows over typical airfoils and wing. The numerical results show that the convergence of the method presented is much faster than its explicit counterpart. It is also demonstrated that the presented methods still functions for compressible transonic flow simulations and additionally, for nearly incompressible flow simulations at low Mach numbers as well. Finally, the flows over wing-body configuration at low Mach number are simulated, which intends to show the potential ability of the method presented for coping with flows over practical aerodynamic geometries.

Abstract:A kind of dissimilar steel assembled wheel with B500CL as inner rim and Q345B as outer rim material is designed, and a multi-variable cyclic load fatigue endurance test method is used to predict the fatigue life of the wheel. Based on finite element method, the strength and stiffness of the wheel under different loads and the fatigue life and safety factor under different stress frequencies are calculated, and the key parts of local large stress are analyzed. A parameterized model is established in the turning condition, and 8 structural design variables are defined. The initial sample points are selected by using the optimal Latin hyper-square experimental design method and the Kriging approximate model of wheels is fitted. Taking the minimum mass, fatigue life and the maximum fatigue life safety coefficient of the wheel as the objective, and taking the stress and the maximum shape variables as the constraints, the multi-objective optimization of the wheel was carried out, and the bending fatigue test was conducted for verification. The results show that the dissimilar steel assembled wheels have good performance and meet the design life requirement after optimization. Compared with the wheel before optimization, the quality of dissimilar steel assembled wheels is reduced by 9.73%.

Abstract:To improve the reliability and performance of hydraulic axial piston pump, the reliability design method of volumetric efficiency, one of the main performance indexes of axial piston pump, was investigated. The instantaneous leakage flow rate and volumetric efficiency of the axial piston pump with the cylinder body at any instantaneous angle are deduced by comprehensively analyzing the instantaneous leakage of a single piston. The reliability and reliability sensitivity analysis method of the axial piston pump are established by using the random perturbation theory and the fourth-order moment technology, and the accuracy and rationality of the proposed method are verified by Monte Carlo method. The results show that the reliability of the hydraulic axial piston pump fluctuates periodically with the angle of the cylinder block, the reliability is the lowest when the piston passes through the top dead center, although the reliability fluctuates relatively greatly when the number of pistons is 9, but its overall reliability level is higher than that of the 8 pistons. The clearance between the slipper and the swash plate, and between the cylinder block and the port plate has a greater impact on the reliability, while the clearance between the piston and the piston chamber, and between the slipper and the piston ball hinge has a smaller impact. The method presented in this paper provides a theoretical reference for the research, design, process and quality control of axial piston pump.

Abstract:The high-temperature gas leakage flow generated by the turbine tip clearance not only reduces the turbine efficiency, but also exacerbates the thermal load on the tip. Based on experimental model and numerical calculation method of fluid-solid coupling, the flow mechanism of the interaction between gap flow and cooling jet at the tip of turbine groove and the effect of top jet cooling on the heat transfer effect of the groove wall are studied. The effects of the ratio of cooling hole inclination angle, the cooling hole inlet angle, and the thermal conductivity of the solid material on the Nu number of the wall surface are analyzed. The results show that the large blow ratio (M=1.5) can effectively improve the heat transfer between the rib and the bottom of groove near the pressure side, and the Nu number distribution is more uniform. The "jet effect" generated by the intake angle changes the high-speed zone of the cooling airflow. Relative position of the outlet, when the intake angle β>0°, the cooling gas can effectively block the high temperature fluid to reduce the Nu number of the wall surface. The low thermal conductivity material reduces the convective heat transfer of the airflow to the solid wall, so that the convective heat transfer of the wall surface is more uniform.

Abstract:To overcome some inherent drawbacks regarding the assessment of relationships between customer requirements and engineering characteristics, the determination of customer requirements weights and the prioritization of engineering characteristics in application of traditional QFD method, a novel QFD method considering expert’s psychological behavior character under probabilistic linguistic environment was proposed. Firstly, the initial weights of customer requirements were determined by using the probabilistic linguistic multiplicative analytic hierarchy process (PL-MAHP). With respect to the interrelationships among customer requirements into account, fuzzy cognitive map (FCM) was used to analyze and determine their final weights. Secondly, the probabilistic linguistic sets (PLTS) was applied to express the uncertainty and hesitancy of subjective assessments in evaluating the interrelations between customer requirements and engineering characteristics. in addition, the TODIM method was extended to probabilistic linguistic environment, the overall dominance of engineering characteristics was utilized to determine the importance ranking of engineering characteristics considering the psychological behaviors of decision makers. Finally, the proposed QFD method was applied in an empirical case concerning the product development of electric vehicle, the results proved that the method can effectively prioritise engineering characteristics in QFD, and comparison study with other relevant methods was also performed to show its merits.