A new code concept is used for the L1 civil（L1C） signal of the global positioning system（GPS）.The generation of L1C codes is quite different from the generation of traditional ranging codes.Thus,it is necessary to...A new code concept is used for the L1 civil（L1C） signal of the global positioning system（GPS）.The generation of L1C codes is quite different from the generation of traditional ranging codes.Thus,it is necessary to find a method for the correct generation to pave the way for future research.L1C codes are based on only one Legendre sequence which consists of Legendre symbols.To calculate these Legendre symbols,the Euler criterion is always used to evaluate quadratic residues.However,due to the great length of L1C codes,this procedure causes overflow problems.Therefore,the quadratic reciprocity law,some related theorems and properties are introduced to solve the problems.Moreover,if the quadratic reciprocity law,some related theorems and properties are used to calculate different Legendre symbols,the combination modes may vary,which causes a complex generation process.The proposed generation method deals with this complex generation process effectively.In addition,through simulations,it is found that the autocorrelation features of obtained Legendre sequences and L1C codes are in accordance with theoretical results,which proves the correctness of the proposed method.展开更多
This paper studied the reciprocity effect between wollastonite and a strain silicate bacterium from purple soil. We analyzed the changes of pH value, glucose (GLU) residual concentration, electrolyte and Mn, Si, Fe et...This paper studied the reciprocity effect between wollastonite and a strain silicate bacterium from purple soil. We analyzed the changes of pH value, glucose (GLU) residual concentration, electrolyte and Mn, Si, Fe etc. in the culture liquid with wollastonite after 48 h. The results show that the GLU wastage of silicate bacteria with wollastonite is 2.5 times of the bacterial contrast. It showed wollastonite could obviously accelerate silicate bacteria growth, but bacterial cell broken and distorted badly have been found by SEM analysis. The solubilization of silicate bacteria to Si element of wollastonite reached above 10 times. At the same time, three apices in FTIR of wollastonite (898 cm-1, 925 cm-1, 962 cm-1) descended obviously after the action of silicate bacteria, which shows that a great deal of Si has dissolved out. So we can get that wollastonite has remarkable effect to the growth of silicate bacteria and silicate bacteria has obvious solubilization to Si of wollastonite.展开更多
The ammunition loading system manipulator is susceptible to gear failure due to high-frequency,heavyload reciprocating motions and the absence of protective gear components.After a fault occurs,the distribution of fau...The ammunition loading system manipulator is susceptible to gear failure due to high-frequency,heavyload reciprocating motions and the absence of protective gear components.After a fault occurs,the distribution of fault characteristics under different loads is markedly inconsistent,and data is hard to label,which makes it difficult for the traditional diagnosis method based on single-condition training to generalize to different conditions.To address these issues,the paper proposes a novel transfer discriminant neural network(TDNN)for gear fault diagnosis.Specifically,an optimized joint distribution adaptive mechanism(OJDA)is designed to solve the distribution alignment problem between two domains.To improve the classification effect within the domain and the feature recognition capability for a few labeled data,metric learning is introduced to distinguish features from different fault categories.In addition,TDNN adopts a new pseudo-label training strategy to achieve label replacement by comparing the maximum probability of the pseudo-label with the test result.The proposed TDNN is verified in the experimental data set of the artillery manipulator device,and the diagnosis can achieve 99.5%,significantly outperforming other traditional adaptation methods.展开更多
A numerical triangulation and transformation into the time domain of a Kirchhoff approximation(KA)method is proposed for the modeling of bistatic scattering from an underwater non-penetrable target.The time domain sol...A numerical triangulation and transformation into the time domain of a Kirchhoff approximation(KA)method is proposed for the modeling of bistatic scattering from an underwater non-penetrable target.The time domain solution in this approximation can be split up into two parts:the solution of reflected field,contributing around the specular direction,and the solution of shadow radiation,contributing around the forward direction.An average solution in the time domain satisfying the reciprocity principle is presented.The solution is expressed in terms of non-singular functions.The proposed method is validated against a normal mode method for bistatic scattering from a rigid sphere.Moreover,the reflected and shadow highlights on the surface of the sphere are shown to verify the integration surface of the reflected field and shadow radiation.It is also tested against a finite element method and an experiment involving a scaled Benchmark Target Strength Simulation Submarine model.The time-angle bistatic spectra for the model are evaluated by the direct and transformed average solutions of KA,and the former accelerates its speed of calculation.The results are good,and show that this method can be used to predict the bistatic scattered field of a non-penetrable target.展开更多
Single cell temperature difference of lithium-ion battery(LIB) module will significantly affect the safety and cycle life of the battery. The reciprocating air-flow module created by a periodic reversal of the air flo...Single cell temperature difference of lithium-ion battery(LIB) module will significantly affect the safety and cycle life of the battery. The reciprocating air-flow module created by a periodic reversal of the air flow was investigated in an effort to mitigate the inherent temperature gradient problem of the conventional battery system with a unidirectional coolant flow with computational fluid dynamics(CFD). Orthogonal experiment and optimization design method based on computational fluid dynamics virtual experiments were developed. A set of optimized design factors for the cooling of reciprocating air flow of LIB thermal management was determined. The simulation experiments show that the reciprocating flow can achieve good heat dissipation, reduce the temperature difference, improve the temperature homogeneity and effectively lower the maximal temperature of the modular battery. The reciprocating flow improves the safety, long-term performance and life span of LIB.展开更多
The measurement and prediction of gas pulsations are performed along the discharge pipeline of a reciprocating compressor for a refrigerator. A regression based experimental model of the one-dimensional acoustic field...The measurement and prediction of gas pulsations are performed along the discharge pipeline of a reciprocating compressor for a refrigerator. A regression based experimental model of the one-dimensional acoustic field is developed. First, the conventional method for gas pulsation measurement and prediction, which separates the incident and reflected wave of acoustic waves traveling in the frequency domain, is discussed. Then, regression based on our proposed simple model, which is able to predict gas pulsation compared to the conventional method, is introduced for the analysis of a reciprocating compressor(The conventional method requires the value of sound speed in the piping line for the reciprocating compressor). A numerical prediction is made for the regression method. Three power spectrum values along the discharge pipeline are used for analysis, and two values are used for verification. Our results are in a good agreement with the conventional method.展开更多
The design solutions for breadth cam mechanism was presented. The main topics of the shape design for breadth cam was to calculate the coordinate at each contact point to determine the cam profile. The proposed method...The design solutions for breadth cam mechanism was presented. The main topics of the shape design for breadth cam was to calculate the coordinate at each contact point to determine the cam profile. The proposed method according to velocity and geometric relationships of instant velocity centers can easily determine each contact point at any instant moment. The cam profile was defined by contouring of the contact points. And also a program was developed by using Microsoft Visual C++ program,which can quickly and easily draw a 2D cam profile through the displacement diagram. Finally,the program was used to confirm the accuracy on the breadth cam profile design by computer animation graphically.展开更多
An overview of some popular rotary and reciprocating positive displacement( PD) pump types is given with the objective of presenting and comparing the respective sizing relationships and performance features. Reciproc...An overview of some popular rotary and reciprocating positive displacement( PD) pump types is given with the objective of presenting and comparing the respective sizing relationships and performance features. Reciprocating pumps discussed are the piston and plunger types. Rotary pumps addressed are gear( external and internal),vane,lobe,screw,and liquid ring pumps. To put the relative pump sizes in perspective,attention is fixed on the rotors or reciprocating elements of PD pumps,just as impellers indicate the sizes of rotodynamic pumps. The size of a PD pump is found from a dimensionless combination of displacement flow rate,rotative speed and diameter. The flow rate,head( or pressure rise) and power are related through the component efficiencies. The cavitation coefficient,often close to unity,connects the rotor tip speed or piston speed with the required NPSH,which can also be affected by the pressure rise of the pump due to leakage across the internal clearances. Operational effects due to cavitation,ingestion of gas or abrasives,and viscous and non-Newtonian fluids are discussed.展开更多
基金supported by the National High Technology Research and Development Program of China(863Program)(2011AA110101)the National Basic Research Program of China(973Program)(2009CB724002)
文摘A new code concept is used for the L1 civil（L1C） signal of the global positioning system（GPS）.The generation of L1C codes is quite different from the generation of traditional ranging codes.Thus,it is necessary to find a method for the correct generation to pave the way for future research.L1C codes are based on only one Legendre sequence which consists of Legendre symbols.To calculate these Legendre symbols,the Euler criterion is always used to evaluate quadratic residues.However,due to the great length of L1C codes,this procedure causes overflow problems.Therefore,the quadratic reciprocity law,some related theorems and properties are introduced to solve the problems.Moreover,if the quadratic reciprocity law,some related theorems and properties are used to calculate different Legendre symbols,the combination modes may vary,which causes a complex generation process.The proposed generation method deals with this complex generation process effectively.In addition,through simulations,it is found that the autocorrelation features of obtained Legendre sequences and L1C codes are in accordance with theoretical results,which proves the correctness of the proposed method.
文摘This paper studied the reciprocity effect between wollastonite and a strain silicate bacterium from purple soil. We analyzed the changes of pH value, glucose (GLU) residual concentration, electrolyte and Mn, Si, Fe etc. in the culture liquid with wollastonite after 48 h. The results show that the GLU wastage of silicate bacteria with wollastonite is 2.5 times of the bacterial contrast. It showed wollastonite could obviously accelerate silicate bacteria growth, but bacterial cell broken and distorted badly have been found by SEM analysis. The solubilization of silicate bacteria to Si element of wollastonite reached above 10 times. At the same time, three apices in FTIR of wollastonite (898 cm-1, 925 cm-1, 962 cm-1) descended obviously after the action of silicate bacteria, which shows that a great deal of Si has dissolved out. So we can get that wollastonite has remarkable effect to the growth of silicate bacteria and silicate bacteria has obvious solubilization to Si of wollastonite.
文摘The ammunition loading system manipulator is susceptible to gear failure due to high-frequency,heavyload reciprocating motions and the absence of protective gear components.After a fault occurs,the distribution of fault characteristics under different loads is markedly inconsistent,and data is hard to label,which makes it difficult for the traditional diagnosis method based on single-condition training to generalize to different conditions.To address these issues,the paper proposes a novel transfer discriminant neural network(TDNN)for gear fault diagnosis.Specifically,an optimized joint distribution adaptive mechanism(OJDA)is designed to solve the distribution alignment problem between two domains.To improve the classification effect within the domain and the feature recognition capability for a few labeled data,metric learning is introduced to distinguish features from different fault categories.In addition,TDNN adopts a new pseudo-label training strategy to achieve label replacement by comparing the maximum probability of the pseudo-label with the test result.The proposed TDNN is verified in the experimental data set of the artillery manipulator device,and the diagnosis can achieve 99.5%,significantly outperforming other traditional adaptation methods.
基金the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(project number SL2021PT108)。
文摘A numerical triangulation and transformation into the time domain of a Kirchhoff approximation(KA)method is proposed for the modeling of bistatic scattering from an underwater non-penetrable target.The time domain solution in this approximation can be split up into two parts:the solution of reflected field,contributing around the specular direction,and the solution of shadow radiation,contributing around the forward direction.An average solution in the time domain satisfying the reciprocity principle is presented.The solution is expressed in terms of non-singular functions.The proposed method is validated against a normal mode method for bistatic scattering from a rigid sphere.Moreover,the reflected and shadow highlights on the surface of the sphere are shown to verify the integration surface of the reflected field and shadow radiation.It is also tested against a finite element method and an experiment involving a scaled Benchmark Target Strength Simulation Submarine model.The time-angle bistatic spectra for the model are evaluated by the direct and transformed average solutions of KA,and the former accelerates its speed of calculation.The results are good,and show that this method can be used to predict the bistatic scattered field of a non-penetrable target.
基金Project(50803008)supported by the National Natural Science Foundation of ChinaProjects(14JJ4035,2011RS4067)supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project(2013-sdllmd-08)supported by the State Key Laboratory of Luminescent Materials and Devices(South China University of Technology),ChinaProjects(20100480946,201104508)supported by the China Postdoctoral Science Foundation,China
文摘Single cell temperature difference of lithium-ion battery(LIB) module will significantly affect the safety and cycle life of the battery. The reciprocating air-flow module created by a periodic reversal of the air flow was investigated in an effort to mitigate the inherent temperature gradient problem of the conventional battery system with a unidirectional coolant flow with computational fluid dynamics(CFD). Orthogonal experiment and optimization design method based on computational fluid dynamics virtual experiments were developed. A set of optimized design factors for the cooling of reciprocating air flow of LIB thermal management was determined. The simulation experiments show that the reciprocating flow can achieve good heat dissipation, reduce the temperature difference, improve the temperature homogeneity and effectively lower the maximal temperature of the modular battery. The reciprocating flow improves the safety, long-term performance and life span of LIB.
基金Project supported by the 2010 Yeungnam University Research Grant,Korea
文摘The measurement and prediction of gas pulsations are performed along the discharge pipeline of a reciprocating compressor for a refrigerator. A regression based experimental model of the one-dimensional acoustic field is developed. First, the conventional method for gas pulsation measurement and prediction, which separates the incident and reflected wave of acoustic waves traveling in the frequency domain, is discussed. Then, regression based on our proposed simple model, which is able to predict gas pulsation compared to the conventional method, is introduced for the analysis of a reciprocating compressor(The conventional method requires the value of sound speed in the piping line for the reciprocating compressor). A numerical prediction is made for the regression method. Three power spectrum values along the discharge pipeline are used for analysis, and two values are used for verification. Our results are in a good agreement with the conventional method.
基金Work supported by the Second Stage of Brain Korea 21 Projects
文摘The design solutions for breadth cam mechanism was presented. The main topics of the shape design for breadth cam was to calculate the coordinate at each contact point to determine the cam profile. The proposed method according to velocity and geometric relationships of instant velocity centers can easily determine each contact point at any instant moment. The cam profile was defined by contouring of the contact points. And also a program was developed by using Microsoft Visual C++ program,which can quickly and easily draw a 2D cam profile through the displacement diagram. Finally,the program was used to confirm the accuracy on the breadth cam profile design by computer animation graphically.
文摘An overview of some popular rotary and reciprocating positive displacement( PD) pump types is given with the objective of presenting and comparing the respective sizing relationships and performance features. Reciprocating pumps discussed are the piston and plunger types. Rotary pumps addressed are gear( external and internal),vane,lobe,screw,and liquid ring pumps. To put the relative pump sizes in perspective,attention is fixed on the rotors or reciprocating elements of PD pumps,just as impellers indicate the sizes of rotodynamic pumps. The size of a PD pump is found from a dimensionless combination of displacement flow rate,rotative speed and diameter. The flow rate,head( or pressure rise) and power are related through the component efficiencies. The cavitation coefficient,often close to unity,connects the rotor tip speed or piston speed with the required NPSH,which can also be affected by the pressure rise of the pump due to leakage across the internal clearances. Operational effects due to cavitation,ingestion of gas or abrasives,and viscous and non-Newtonian fluids are discussed.
