Abstract:In order to deal with the complex situation that parametric uncertainty and correlation coexist in the automotive powertrain mounting system (PMS),an uncertainty analysis method for calculating the natural frequency and decoupling rate of PMS was proposed.In the proposed method,the multi-dimensional parallelepiped model was firstly constructed to describe the PMS parameters with uncertainty and correlation.Then,the uncertain responses of the natural frequency and decoupling rate were calculated by integrating the regulation technique,Taylor series expansion and central difference method.Next,the analysis procedure of the proposed method was presented.Finally,the Monte Carlo method was used as a reference method for comparison and verification.The numerical analysis results show that the correlation of uncertain parameters of PMS has a certain influence on the inherent characteristics of the system.The method presents acceptable computational accuracy and higher computational efficiency in solving the uncertain response of PMS,which provides important reference for the calculation,evaluation and optimization design of the inherent characteristics of automotive PMS.

Abstract:In order to improve the rescue efficiency of the advanced automatic crash notification (AACN) system,a driver injury prediction algorithm was proposed,and the overall design of the AACN system terminal was conducted based on this algorithm.First,the amount of speed change,the direction of the accident,the driver′s age,gender,whether to wear the seat belt,and whether the driver′s side airbag inflated were selected as the influencing factors of the driver′s injury.Next,a Logistic regression model was analyzed and developed based on traffic accident data.The effectiveness of the model was verified by using the Hosmer-Lemeshow test table,and the best trigger threshold was obtained through sensitivity analysis.Then,the AACN system terminal was designed.Finally,an actual case was used to test the accuracy of the injury prediction algorithm and the effectiveness of AACN system terminal.The results of the case study show that the proposed driver injury prediction algorithm and the AACN system are highly accurate,which can effectively predict the driver′s injury and help the rescue center work out an active rescue plan.The research results can be used to solve the problem that existing centralized AACN systems′ efficiency is not high and their accuracy is greatly affected by human factors.Consequently,they provide a reference for the design of driver injury prediction algorithm in the decentralized AACN system.

Abstract:In order to improve the serious problem of "[KG-*2]collision" when the retarder is installed in the transmission system of a semi-trailer vehicle,and to improve the braking energy recovery rate during retarding conditions,a scheme of energy recovery type retarder installed in the hub on both sides of the front axle of semi-trailer was proposed.According to the regulation of retarder braking performance in GB/T 32692-2016,the retarder parameters were matched,and the corresponding retarder control strategy was proposed.According to the quality requirements of the electric semitrailer train in the control strategy,the quality estimation algorithm was studied,and based on the particle swarm algorithm,the braking torque distribution at low braking intensity was studied.A joint simulation platform was built through Matlab/Simulink and TruckSim to simulate and verify the quality estimation algorithm,the economy of electric semitrailer trains and braking safety.The simulation results show that the quality estimation algorithm can accurately estimate the quality of electric semitrailer trains; the energy recovery retarder can meet the retardation requirements of electric semi-trailer vehicles,improve the braking energy recovery rate,and can effectively improve the "[KG-*2]collision" problem of the electric semi-trailer train during slow braking.Related research provides new ideas for improving the braking energy recovery rate of electric semi-trailer vehicles during slow braking,and can improve the "[KG-*2]collision" problem and improve braking safety.

Abstract:In order to improve the microstructure and properties of hot spraying coating for bearing of high speed rolling mill,induction remelting was carried out on the Ni60A coating which was prepared on the surface of GCr15 Bearing Steel by high energy flame spraying.The porosity,microstructure and microhardness of the coating before and after induction remelting were analyzed comparatively by metallographic microscope,scanning electron microscope,X-ray diffractometer and microhardness tester.The effect of induction remelting on the microstructure and microhardness of the coating and interface was investigated.The results show that the porosity of nickel based coating prepared by high energy flame spraying is as high as 509%,and there are many surface pore defects,as well as there are obvious interface cracks and pore defects at the interface between the coating and the substrate,showing typical mechanical bonding and poor interface bonding properties.However,after the induction remelting,the microstructure of the coating is dense,the porosity is only 027%,the defects of the coating are obviously reduced,and the bonding interface between the coating and the substrate shows strong metallurgical fusion characteristics.Additionally,the amount of hard phase in the coating increases significantly,and the microhardness of the coating and interface is greatly improved.Therefore,the induction remelting process can not only improve the surface quality of hot spraying coating for high-speed rolling mill bearings,but also improve the interface bonding characteristics of the coating.The application of induction remelting technology can improve the coating surface structure property,and it may be used in the surface strenthening of high-speed rolling mill bearings for some point.

Abstract:In order to improve the basic theory of boundary value problems for nonlinear quantum difference equations,in this paper,we study the solvability of nonlocal problems for second order three-point nonlinear (p,q)-difference equations.Firstly,the Green function of the boundary value problem of linear (p,q)-difference equation is calculated and the property of Green function is studied.Secondly,we obtain the existence and uniqueness of the positive solution for the problem by the Banach contraction mapping principle and the Guo-Krasnoselskii fixed point theorem in a cone.Next,we get the Lyapunov inequality for nonlocal problems of linear (p,q)-difference equations.Finally,two examples are given to illustrate the validity of the results.The results show that the existence and uniqueness of positive solutions for nonlocal problems of nonlinear (p,q)-difference equations are obtained,under the condition of nonlinear term f certain growth.The research results enrich the theory of solvability of quantum difference equations and provide important theoretical basis for the application of(p,q)-difference equation in mathematics,physics and other fields.

Abstract:In order to extend the basic theory of nonlinear discrete boundary value problems,this paper studied the sufficient conditions for the existence of positive solutions for a class of nonlinear second-order difference equations with three-point boundary value problems.Firstly,the expressions of the solutions for the corresponding three-point boundary value problems for second-order difference equations were given and their properties were proved; Secondly,by constructing suitable cone and integral operator in Banach space and utilizing Krasnoselskii's fixed point theorem in cones,the sufficient conditions for the existence of positive solutions of three-point boundary value problems for nonlinear second-order difference equations were obtained under the condition that the nonlinear term was allowed to change sign.Finally,two examples were given to illustrate the validity of the main theorems and results.The results show that the conditions of the theorem are proved and the discrete boundary value problems satisfies the existence condition of positive solutions.The method is effective in the theoretical proof of the second-order discrete boundary value problem,and has reference for the study of the nonlinear high-order multi-point discrete boundary value problems.

Abstract:In order to effectively improve the fault detection and monitoring performance of support vector machine (SVM) algorithm,a new fault detection algorithm of industrial process based on DW-ICA-SVM was proposed.Firstly,the training data was normalized.The independent component analysis (ICA) was used to obtain the independent component matrix of the data and extract the hidden non-Gaussian information.Then the Durbin-Watson (DW) criterion was used to calculate the DW values of the independent components (ICs).The DW method was used to effectively extract important noise information and select the important ICs.The ICs containing important information were used as the input of the SVM model to obtain the discriminant classification function.The ICs of test data were input to the model for fault detection and monitoring.Finally,the method was applied to the nonlinear numerical example and the Tennessee-Eastman industrial process,and compared with PCA,LPP,ICA,SVM and ICA-SVM methods.The results show that the proposed method reduces the autocorrelation among samples and effectively improves the fault detection rate.The proposed method strengthens the extraction and recognition of hidden non-Gaussian information to a certain extent,and provides a reference for improving the performance of SVM algorithm in fault detection of industrial process.

Abstract:In order to solve the problem of low accuracy of sentiment classification caused by neglecting the sentiment information of words in distributed word representation method,an improved sentiment analysis method incorporating weighted word vectors of sentiment information was proposed.According to the exclusive domain sentiment dictionary,combined with the dictionary and semantic rules,the sentiment information is integrated into the TF-IDF algorithm,and the weighted word vector representation method is obtained by using word2vec model.The method is used to compare the collected comments of tourist attractions in Hebei Province with the control group.The results show that compared with the sentiment analysis method based on distributed word vector representation,the accuracy and recall rate of positive text are increased by 61% and 66%,and the F value reached 903%,the accuracy and recall rate of negative text are increased by 60% and 72%,and the F value reached 896% by using the improved method of sentiment analysis integrated with sentiment information weighted word vector.Therefore,the improved method of sentiment analysis integrated with sentiment information weighted word vector can effectively improve the accuracy of sentiment analysis of comment text,and provide valuable reference for users to obtain more accurate comments.

Abstract:In order to enhance the aqueous solubility and stability of etoposide preparation,the central composite design-response surface method was used to optimize the prescription technology of etoposide nano-mixed micelles (ETP mPEG-PLA/P123).Based on the results of single factor test,central composite design-response surface method of three factors and five levels was carried out to optimize the prescription technology with drug dosage,the mass ratio of mPEG-PLA and hydration volume as independent variables,and the entrapment efficiency,drug loading and particle size as dependent variables.The critical micelle concentration (CMC) was determined by fluorescence probe method,and the physicochemical properties and release behavior of the prepared micelle preparations were evaluated.The results showed that the optimal prescription of ETP mPEG-PLA/P123 micelle preparation was that mPEG-PLA∶P123=38∶62,the drug dosage was 5 mg,and the hydration volume was 6 mL.After optimization,the entrapment efficiency and drug loading were 874% and 419%,the particle size was 1156 nm,PDI was 0216,and Zeta potential was -163 mV.The CMC value was 17×10-3 g/L,so mPEG-PLA/P123 micelles had high stability.In vitro release experiments,etoposide could be released from micelles slowly and continuously,up to 80% within 48 h.The optimized ETP mPEG-PLA/P123 nano-mixed micelles were able to enormously improve the aqueous solubility of etoposide,and the micelle preparation had good stability and a certain slow-release effect.The results of this study could provide theoretical guidance for further broadening the range of application of new etoposide preparations.

Abstract:Ischemic stroke is a common acute cerebrovascular disease in the middle-aged and elderly,and one of the most fatal diseases in the world.There are limited treatment options that currently exist and only apply to a small proportion of stroke patients,so developing effective treatments to reduce brain damage is critical.Astrocytes are the core components of the central nervous system.Mitochondrial dysfunction is the initial event of ischemic stroke and plays an important role in neuronal survival and neurological function improvement.In this paper,based on the role of astrocytic mitochondria in the pathogenesis of ischemic stroke,the changes of the biological energy and dynamics of astrocytic mitochondria,the functional transfer to neurons and the regulation of astrocytic mitochondria on cerebral blood flow by astrocytic mitochondrice were discussed.Emphasized that astrocytic mitochondria can be used as one of the targets for the treatment of ischemic stroke,so as to better understand the role of astrocytic mitochondria in the process of ischemia-induced neuronal death,and to provide a theoretical basis for the new treatment of ischemic stroke.

Abstract:In order to solve the problem that the glass forming ability of Al-based amorphous alloy is not easy to be evaluated because of the easy precipitation of α-Al crystal in the glass forming process,a simple and feasible glass forming ability evaluation scheme was designedto optimize the composition of amorphous AlNiZr alloy.Firstly,nine kinds of AlNiZr alloy ingots with different compositions were prepared; Then,under the same preparation conditions,the alloy ribbons with different compositions were prepared by single-roll strip casting method; Finally,the ribbons were characterized by XRD,and the amorphous content of alloy ribbon was calculated based on the XRD results.The results show that the glass-forming ability of Al100-x-yNixZry increases with the increase of Ni content and decreases with the increase of Zr content; When the Zr content is 3% and the Ni content is further increased to 20% and 25%,[JP2]the glass-forming ability of the alloy is reduced,and Al82Ni15Zr3[JP] alloy has better glass-forming ability.By optimizing the compositions of amorphous AlNiZr alloy,a new evaluation scheme of glass-forming ability can be provided for the Al-based alloy without rare earth elements,and its application space in the field of equipment protection can be expanded.

Abstract:In order to clarify the influence of rainfall on the seepage field and stability of embankment slope,the mechanism of embankment slope water failure and its main influencing factors were studied.Under the specific control conditions of soil quality,compaction degree and erosion infiltration time,this study explored the erosion damage of subgrade slope under rainfall through slope model test,and then combined with GeoStudio program to find out the seepage field and stability change law of subgrade slope during rainfall.The results show that in the process of rainfall,the slope surface is scoured by rain water and the external structure is damaged,while the internal stability of the slope is reduced by the seepage action of rain water.The two effects from the outside to the inside simultaneously lead to the overall damage of the slope.With the increase of compaction degree of two kinds of soil slopes from 85% to 95%,the erosion amount of sandy soil slopes decreased by 4618%,and the slope safety factor increased by 1374%,while the erosion amount of cohesive soil slopes decreased by 3370%,and the safety factor increased by 1021%.With the increase of rainfall time,the scouring depth of cohesive soil slope tends to be stable in the later stage,while the scouring depth of sandy soil slope tends to increase; Under the same control conditions,the change of safety factor of cohesive soil slope before and after rainfall is smaller than that of sandy soil slope.Under the same control conditions,the water damage resistance and overall stability of the clay soil slope are stronger than that of the sandy soil slope.The research results are helpful for more comprehensive understanding of the water-damage mechanism of the embankment slope and the influence laws of the main factors in the process of rainfall,and improve the stability of the road support.

Abstract:In order to solve the problems that the irreversible loss existing in the gas cooler has a great influence on its heat transfer performance,in order to improve the thermal performance of the straight tube tube-in-tube gas cooler,the heat transfer process between carbon dioxide and cooling water in supercritical carbon dioxide tube-in-tube gas cooler was studied.By using Fluent software and entropy generation analysis method,the temperature distribution of carbon dioxide and cooling water along the pipe length was obtained throught changing the operating pressure,carbon dioxide mass flow,cooling water mass flow and inlet temperature;according to the entropy generation analysis method of the second law of thermodynamics,the thermodynamic process in the straight pipe casing was calculated,and the entropy generation distribution along the tube length was obtained.The results show that the entropy production along the tube length increases with the increase of pressure;with the increase of carbon dioxide mass flow,the entropy production gradually decreases;with the increase of cooling water mass flow rate,the increase of entropy production is not obvious;with the increase of cooling water inlet temperature,entropy production decreases.The research result may provide some reference for the operation parameters and structure design of CO2 heat pump gas cooler,as well as for the engineering application of CO2 heat pump.