Brain lesions,such as those caused by stroke or traumatic brain injury(TBI),frequently result in persistent motor and cognitive impairments that significantly affect the individual patient's quality of life.Despit...Brain lesions,such as those caused by stroke or traumatic brain injury(TBI),frequently result in persistent motor and cognitive impairments that significantly affect the individual patient's quality of life.Despite differences in the mechanisms of injury,both conditions share a high prevalence of motor and cognitive impairments.These deficits show only limited natural recovery.展开更多
Electromagnetic interference(EMI)shielding materials principally attain shielding by reflecting electromagnetic waves through impedance mismatch caused by high conductivity,which inevitably leads to secondary electrom...Electromagnetic interference(EMI)shielding materials principally attain shielding by reflecting electromagnetic waves through impedance mismatch caused by high conductivity,which inevitably leads to secondary electromagnetic wave pollution.Consequently,the development of multifunctional,low-reflection electromagnetic shielding materials remains a significant challenge.Materials that are lightweight,possess high mechanical strength,exhibit excellent electromagnetic shielding absorption,and demonstrate low reflectivity have historically been the focus of significant interest.Natural silk,lightweight and strong,is an ideal composite matrix.Regenerated silk fibroin(RSF)synthesized via a bottom-up approach and cross-linked with polyvinyl alcohol(PVA)forms an aerogel matrix with remarkable compressive strength.In accordance with the principle of integrating functional design with structural design,spherical NiFe_(2)O_(4)particles were grown on the MXene surface via electrostatic self-assembly and combined with RSF/PVA as the aerogel absorptive layer,while RSF/PVA/MXene served as the reflective layer.A vertically oriented structure of Janus aerogel was prepared through sequential directed freezing.The resulting aerogel with 0.058 g/cm^(3) reveals the high compression strength(3.52 MPa).Reasonable functional and structural design enables aerogel to effectively dissipate incident electromagnetic waves through absorption,reflection,and reabsorption processes,achieving an average SET value of 48.05±1.75 dB and reaching a minimum reflection coefficient of 0.19.Furthermore,the aerogel displays remarkable infrared stealth capabilities.This lightweight,rigid,multifunctional aerogel is poised to play a significant role in the field of next-generation electronic devices.展开更多
Many findings have shown that positive and negative transfer from the first language influences the second language acquisition.Some observations illustrate that dialect incurs negative transfer on Mandarin learning.T...Many findings have shown that positive and negative transfer from the first language influences the second language acquisition.Some observations illustrate that dialect incurs negative transfer on Mandarin learning.Twenty-nine English learners of Huangshi dialect are surveyed about their living and education environment,their second language acquisition and Mandarin learning in an attempt to prove the existence of dialect interference on Mandarin and the second language acquisition and explain the reasons of the difference among dialect,Mandarin and the second language acquisition,based on sound analysis.展开更多
Here wc report calculation of the differential interference angles （including b≤p gild b≥p ） for singlet-triplet mixed states of Na2（A^1∑u^＋,ν=8-b^3∏0u,ν=14） system in collision with Na, in order to study t...Here wc report calculation of the differential interference angles （including b≤p gild b≥p ） for singlet-triplet mixed states of Na2（A^1∑u^＋,ν=8-b^3∏0u,ν=14） system in collision with Na, in order to study the collision- induced quantum interference on rotational energy transfer in an atom-diatom system. The calculation is based on the first-order Born approximation of time-dependent perturbation theory, and the anisotropic Lennard-Jones intcraction potentials are also employed, The relationships between differential interference angle and impact parameter, including collision diameter and velocity, are obtained,展开更多
This paper proposes the orthogonal and nonorthogonal schemes in the interference environments for visible light communication（ VLC） systems. The proposed schemes pay attention to the case when different bit streams ...This paper proposes the orthogonal and nonorthogonal schemes in the interference environments for visible light communication（ VLC） systems. The proposed schemes pay attention to the case when different bit streams from multiple cells are simultaneously transmitted, which consequently causes inter-cell interference（ ICI） and greatly deteriorates the bit error rate（ BER） and channel capacity performance of the system. The performance of the newdeveloped multi-cell system in indoor VLC systems is evaluated. The bipolar phase shift keying（ BPSK） modulation scheme with orthogonal pulses（ OPs） for multiple cells environments is employed to mitigate the ICI problem and improve the BER and channel capacity performances. Since the use of different OPs in each cell requires more number of OPs, which requires high bandwidth, OPs are reused at certain distances. Three different schemes, which are OPs,orthogonal and non-orthogonal pulses（ NOP） reuse, are compared. This paper investigates the impact of using these schemes and compared their performances in the ICI environments. The BER and channel capacity using the proposed schemes are comprehensively examined. Simulation and theoretical results showthat the OPs schemes are more effective in the interference areas of the room and significantly outperform NOP.展开更多
In our previous theoretical studies [Meng-Tao Sun, Yong-Qing Lee, and Feng-Cai Ma, Chem. Phys.Left. 371 （2003） 342], we have reported the quantum interference on collision-induced rotational energy transfer on CO （...In our previous theoretical studies [Meng-Tao Sun, Yong-Qing Lee, and Feng-Cai Ma, Chem. Phys.Left. 371 （2003） 342], we have reported the quantum interference on collision-induced rotational energy transfer on CO （A ^1 Π,v = 3） with inert gases, which originates from the difference between the two A-related collision potential energy surfaces. The interference angle, which measures the degree of coherence, is presented in this paper. Based on the time-dependent first order Born approximation, taking into account the anisotropic Lennard-Jones interaction potentials, the relation of the interference angle with the factors, including experimental temperature, partner, and rotational quantum number, are obtained. The changing tendencies with them are discussed. This theoretical model is important to understanding and performing this kind of experiment.展开更多
The key to narrow-band interference excision in frequency domain is to determine the excision thresh- old in direct-sequence spread-spectrum （DS-SS） systems. The excision threshold is a non-linear function related t...The key to narrow-band interference excision in frequency domain is to determine the excision thresh- old in direct-sequence spread-spectrum （DS-SS） systems. The excision threshold is a non-linear function related to the number and the power of interference, and attempting to get the exact relation of threshold related to the number and the power of interference is almost impossible. The N-sigma algorithm determines the excision threshold using subsection function; however, the excision threshold determined by this method is not exact. A new method to determine the threshold of N-sigma algorithm is proposed. The new method modifies the scale factor N by use of the membership function. The threshold determined by this method is consecutive and smooth, and it is closer to the fact than that of the initial N-sigma algorithm. The GPS signal and single-tone （CW） interference （that is, typical narrow-band interference） are implemented in the simulation, and the results are presented to demonstrate the validity of the new algorithm.展开更多
Here we refer the native language to Chinese and the second language to English especially college English. According to linguistic study, there are certain native language interferences in secondlanguage acquisition...Here we refer the native language to Chinese and the second language to English especially college English. According to linguistic study, there are certain native language interferences in secondlanguage acquisition when one is learning the second language,i. e. when a Chinese is learningEnglish, due to the influence of mother tongue which is habitually applied in learning the second language, his pronounciation, his grammar and his vocabulary are quite likely influencedor interfered by his native language or his dialect. Unfortunately, we did find certain first language interferences in our English teaching and learning processes on various items or subjects.展开更多
Collisional quantum interference （CQI） on the intramolecular rotational energy transfer is observed in an experiment with a static cell, and the integral interference angles are measured. To obtain more accurate inf...Collisional quantum interference （CQI） on the intramolecular rotational energy transfer is observed in an experiment with a static cell, and the integral interference angles are measured. To obtain more accurate information, an experiment with a molecular beam is carried out, and thereby the relationship between the differential interference angle and the scattering angle is obtained. Based on the first-Born approximation of time-dependent perturbation theory, the theoretical model of CQI is developed in an atom-diatom system in the condition of the molecular beam, with the long-range interaction potential taken into account. The method of measuring correctly the differential interference angle is presented. The tendencies of the differential interference angle changing with the impact parameter and rel- ative velocity are discussed. The theoretical model presented here is important for understanding or performing the experiment in the molecular beam.展开更多
To study theoretically the relationship between the differential interference angle and the scattering angle in collisional quantum interference （CQI）, we have investigated the differential interference angle of the...To study theoretically the relationship between the differential interference angle and the scattering angle in collisional quantum interference （CQI）, we have investigated the differential interference angle of the atom-diatomic [case（a）] molecule system in detail. For the 2∏ electronic state in Hund＇s case （a）, the degree of the differential interference is also discussed. The differential interference angles of NO（X^2∏） are calculated quantitatively for the rotational energy transfer in Hund＇s case （a） induced by collision with He, Ne and Ar atoms. The method to calculate the differential interference angle is presented. Several factors that affect the differential interference angle are investigated. Finally the variation of the differential interference angle with the impact parameter and relative velocity is discussed.展开更多
This letter presents two preprocessing techniques for narrow-band interference （NBI） rejection in Time- Division-Duplex （TDD） CDMA systems. In the proposed methods, at the transmitter, by using Karhaunen-Loeve Tra...This letter presents two preprocessing techniques for narrow-band interference （NBI） rejection in Time- Division-Duplex （TDD） CDMA systems. In the proposed methods, at the transmitter, by using Karhaunen-Loeve Transform and Discrete Fourier Transform, the transmitted power is set to zero in the directions of the eigenvectors that will be severely contaminated by NBI; and therefore less part of the transmitted energy will be polluted by NBI in channel. The processing is transferred from receiver to transmitter, and thus the complexity of the receiver is significantly reduced. It is assumed that channel state information can be estimated at the transmitter because in symmetric TDD systems each receiver in turn also acts as a transmitter.展开更多
Collisional quantum interference （CQI） in the intramolecular rotational energy transfer was observed in experiment by Sha and co-workers. The interference angle, which measuring the degree of the coherence, were mea...Collisional quantum interference （CQI） in the intramolecular rotational energy transfer was observed in experiment by Sha and co-workers. The interference angle, which measuring the degree of the coherence, were measured in the experiment of the static cell. Based on the first Born approximation of time dependent perturbation theory, taking into accounts the anisotropic Lennard-Jones interaction potentials, this paper describes the theoretical model of CQI in intramolecular rotational energy transfer in an atom-diatom collision system. In the model, the differential interference angle for the experiment of the molecular beam is calculated, the changing tendencies of the differential interference angle with the impact parameter and collision partners are obtained. This theoretical model is important for understanding or performing this kind of experiments.展开更多
Cognitive Radio （CR） can use the fre- quency band allocated to a Primary User （PU） on the premise that it will prevent significant of avoiding causing great interference to the PU. In this paper, we consider a wid...Cognitive Radio （CR） can use the fre- quency band allocated to a Primary User （PU） on the premise that it will prevent significant of avoiding causing great interference to the PU. In this paper, we consider a wideband CR system where the Secondary User （SU） mini- raises its interference to the PU by jointly al- locating the optimal sensing threshold and sub- carrier power. A multi-parameter optimization problem is formulated to obtain the joint opt- imal allocation by alternating direction opti- mization, which minimises the total interfer- ence to the PU over all of the subcarriers sub- ject to the constraints on the throughput, Bit Error Rate （BER） and maximal total power of the SU, the subcarrier rate and interference power of the PU, and the false alarm and mis- detection probabilities of each subcarrier. The simulation results show that the proposed joint allocation algorithm can achieve the desired mitigation on the interference to the PU at the different subcarrier gains.展开更多
As for ultra-precision grinding of difficult-to-process thin-walled complex components with ball-end grinding wheels,interference is easy to occur.According to screw theory and grinding kinematics,a mathematical model...As for ultra-precision grinding of difficult-to-process thin-walled complex components with ball-end grinding wheels,interference is easy to occur.According to screw theory and grinding kinematics,a mathematical model is established to investigate the interference and grinding characteristics of the ball-end wheel.The relationship between grinding wheel inclination angle,C axis rotation angle,grinding position angle and grinding wheel wear are analyzed.As the grinding wheel inclination angle increases,the C axis rotatable range decreases and the grinding position angle increases.The grinding position angle and wheel radius wear show a negative correlation with the C axis rotation angle.Therefore,a trajectory planning criteria for increasing grinding speed as much as possible under the premise of avoiding interference is proposed to design the grinding trajectory.Then grinding point distribution on the ball-end wheel is calculated,and the grinding characteristics,grinding speed and maximum undeformed chip thickness,are investigated.Finally,a complex structural component can be ground without interference,and surface roughness and profile accuracy are improved to 40.2 nm and 0.399 lm,compared with 556 nm and 3.427 lm before ultra-precision grinding.The mathematical model can provide theoretical guidance for the analysis of interference and grinding characteristics in complex components grinding to improve its grinding quality.展开更多
For decreasing the multiple access interference of weaker signal acquisition in direct sequence spread spectrum（DSSS） systems,a new single decision algorithm is presented.The maximum value of correlation results is ...For decreasing the multiple access interference of weaker signal acquisition in direct sequence spread spectrum（DSSS） systems,a new single decision algorithm is presented.The maximum value of correlation results is conventionally detected.However,there may be not only one strong peak among correlation results when the cross-correlation noise is strong enough to affect the correlation results.The proposed algorithm decreases the false alarm probability through the decision of the ratio of the maximum value and the second maximum value of the correlation results.Theoretical analysis and simulation results indicate that the proposed algorithm effectively suppresses the acquisition problem of multiple access interference in DSSS system.展开更多
To solve the problem of the low interference success rate of air defense missile radio fuzes due to the unified interference form of the traditional fuze interference system,an interference decision method based Q-lea...To solve the problem of the low interference success rate of air defense missile radio fuzes due to the unified interference form of the traditional fuze interference system,an interference decision method based Q-learning algorithm is proposed.First,dividing the distance between the missile and the target into multiple states to increase the quantity of state spaces.Second,a multidimensional motion space is utilized,and the search range of which changes with the distance of the projectile,to select parameters and minimize the amount of ineffective interference parameters.The interference effect is determined by detecting whether the fuze signal disappears.Finally,a weighted reward function is used to determine the reward value based on the range state,output power,and parameter quantity information of the interference form.The effectiveness of the proposed method in selecting the range of motion space parameters and designing the discrimination degree of the reward function has been verified through offline experiments involving full-range missile rendezvous.The optimal interference form for each distance state has been obtained.Compared with the single-interference decision method,the proposed decision method can effectively improve the success rate of interference.展开更多
Pointing mechanism is widely used in aerospace field,and its pointing accuracy and stability have high requirements.The pointing mechanism will be affected by external interference when it works.In order to eliminate ...Pointing mechanism is widely used in aerospace field,and its pointing accuracy and stability have high requirements.The pointing mechanism will be affected by external interference when it works.In order to eliminate the impact of interference forces on the output accuracy of the mechanism,firstly,this paper proposes a design method for highprecision pointing mechanisms based on interference separation,aiming at the high-precision pointing requirements of pointing mechanisms.Based on the screw theory,a synthesis method for inner compensation mechanisms has been proposed.And a new type of double-layer parallel mechanism has been designed to compensate for interference forces.Then,the kinematics and dynamics of the mechanism are carried out.An evaluation index for compensating external interference forces is proposed.The interference compensation analysis is conducted for the pointing mechanism.The correctness of the proposed interference force compensation coefficient is verified.Finally,in order to find the optimal solution for the workspace and interference force compensation coefficient of the pointing mechanism,multi-objective optimization design of the structural parameters of the mechanism was carried out based on the particle swarm optimization algorithm.This provides a theoretical basis for the prototype design of the subsequent double-layer parallel mechanism.This double-layer parallel mechanism combines the advantages of large load-bearing capacity,large workspace,and high output accuracy.It can be better applied in the aerospace field where high-precision pointing and force interference compensation are integrated.展开更多
A high-precision method of detecting motion straightness was proposed based on the prin- ciple of plane mirror interference after analyzing the motion straightness error of a linear stage. De- tection experiments were...A high-precision method of detecting motion straightness was proposed based on the prin- ciple of plane mirror interference after analyzing the motion straightness error of a linear stage. De- tection experiments were carried out and the motion straightness errors were separated by the linear regression method. Finally, linear measurement uncertainty of the detection method was estimated. The results showed that this detection method was simple and accurate, and was especially suitable for precision detection of motion straightness error in the small travel movement of ultra-precision machining.展开更多
A novel communication receiver which uses lapped transform(LT) incorporating modified median filter(MMF) algorithm was designed for narrow band interference(NBI) excision.Comparing to traditional Fourier Transform,LT ...A novel communication receiver which uses lapped transform(LT) incorporating modified median filter(MMF) algorithm was designed for narrow band interference(NBI) excision.Comparing to traditional Fourier Transform,LT has longer basis vectors,less spectral leakage,thus better frequency resolution.The LT domain MMF algorithm takes full advantages of the direct sequence spread spectrum signal,as well as the characteristics of LT,performs the transform domain filtering twice.The first filtering locates the position of interference and mitigates most of them.The second filtering is performed in a small neighborhood of the located interference.So LT domain MMF algorithm can completely mitigate the interference without distorting the desired signal.The simulation results demonstrate the improved BER(Bit Error Rate)performance and increased robustness of our receiver.展开更多
基金supported by the Defitech Foundation(Morges,CH)to FCHthe Bertarelli Foundation-Catalyst program(Gstaad,CH)to FCH+2 种基金the Wyss Center for Bio and Neuroengineering the Lighthouse Partnership for AI-guided Neuromodulation to FCHthe Fonds de recherche du Quebec-Sante(FRQS#342969)to CEPthe Neuro X Postdoctoral Fellowship Program to CEP。
文摘Brain lesions,such as those caused by stroke or traumatic brain injury(TBI),frequently result in persistent motor and cognitive impairments that significantly affect the individual patient's quality of life.Despite differences in the mechanisms of injury,both conditions share a high prevalence of motor and cognitive impairments.These deficits show only limited natural recovery.
基金supported by Key R&D Program of Shandong Province,China(No.2025CXGC010407).
文摘Electromagnetic interference(EMI)shielding materials principally attain shielding by reflecting electromagnetic waves through impedance mismatch caused by high conductivity,which inevitably leads to secondary electromagnetic wave pollution.Consequently,the development of multifunctional,low-reflection electromagnetic shielding materials remains a significant challenge.Materials that are lightweight,possess high mechanical strength,exhibit excellent electromagnetic shielding absorption,and demonstrate low reflectivity have historically been the focus of significant interest.Natural silk,lightweight and strong,is an ideal composite matrix.Regenerated silk fibroin(RSF)synthesized via a bottom-up approach and cross-linked with polyvinyl alcohol(PVA)forms an aerogel matrix with remarkable compressive strength.In accordance with the principle of integrating functional design with structural design,spherical NiFe_(2)O_(4)particles were grown on the MXene surface via electrostatic self-assembly and combined with RSF/PVA as the aerogel absorptive layer,while RSF/PVA/MXene served as the reflective layer.A vertically oriented structure of Janus aerogel was prepared through sequential directed freezing.The resulting aerogel with 0.058 g/cm^(3) reveals the high compression strength(3.52 MPa).Reasonable functional and structural design enables aerogel to effectively dissipate incident electromagnetic waves through absorption,reflection,and reabsorption processes,achieving an average SET value of 48.05±1.75 dB and reaching a minimum reflection coefficient of 0.19.Furthermore,the aerogel displays remarkable infrared stealth capabilities.This lightweight,rigid,multifunctional aerogel is poised to play a significant role in the field of next-generation electronic devices.
文摘Many findings have shown that positive and negative transfer from the first language influences the second language acquisition.Some observations illustrate that dialect incurs negative transfer on Mandarin learning.Twenty-nine English learners of Huangshi dialect are surveyed about their living and education environment,their second language acquisition and Mandarin learning in an attempt to prove the existence of dialect interference on Mandarin and the second language acquisition and explain the reasons of the difference among dialect,Mandarin and the second language acquisition,based on sound analysis.
基金This work was supported by National Natural Science Foundation of China(No.10374040).
文摘Here wc report calculation of the differential interference angles （including b≤p gild b≥p ） for singlet-triplet mixed states of Na2（A^1∑u^＋,ν=8-b^3∏0u,ν=14） system in collision with Na, in order to study the collision- induced quantum interference on rotational energy transfer in an atom-diatom system. The calculation is based on the first-order Born approximation of time-dependent perturbation theory, and the anisotropic Lennard-Jones intcraction potentials are also employed, The relationships between differential interference angle and impact parameter, including collision diameter and velocity, are obtained,
基金The National High Technology Research and Development Program of China(863 Program)(No.2013AA013601)the National Natural Science Foundation of China(No.61223001)+6 种基金the Natural Science Foundation of Jiangsu Province(No.BK20140646)the Research Fund of National Mobile Communication Research Laboratory(No.2014A032014B032014B04)the Research Fund of Zhongxing Telecommunication Equipment Corporationthe Fundamental Research Funds of the Central Universities(No.2242014K40033)the United Creative Foundation of Jiangsu Province(No.BY2013095-1-18)
文摘This paper proposes the orthogonal and nonorthogonal schemes in the interference environments for visible light communication（ VLC） systems. The proposed schemes pay attention to the case when different bit streams from multiple cells are simultaneously transmitted, which consequently causes inter-cell interference（ ICI） and greatly deteriorates the bit error rate（ BER） and channel capacity performance of the system. The performance of the newdeveloped multi-cell system in indoor VLC systems is evaluated. The bipolar phase shift keying（ BPSK） modulation scheme with orthogonal pulses（ OPs） for multiple cells environments is employed to mitigate the ICI problem and improve the BER and channel capacity performances. Since the use of different OPs in each cell requires more number of OPs, which requires high bandwidth, OPs are reused at certain distances. Three different schemes, which are OPs,orthogonal and non-orthogonal pulses（ NOP） reuse, are compared. This paper investigates the impact of using these schemes and compared their performances in the ICI environments. The BER and channel capacity using the proposed schemes are comprehensively examined. Simulation and theoretical results showthat the OPs schemes are more effective in the interference areas of the room and significantly outperform NOP.
基金The project supported by National Natural Science Foundation of China under Grant No. 10374040
文摘In our previous theoretical studies [Meng-Tao Sun, Yong-Qing Lee, and Feng-Cai Ma, Chem. Phys.Left. 371 （2003） 342], we have reported the quantum interference on collision-induced rotational energy transfer on CO （A ^1 Π,v = 3） with inert gases, which originates from the difference between the two A-related collision potential energy surfaces. The interference angle, which measures the degree of coherence, is presented in this paper. Based on the time-dependent first order Born approximation, taking into account the anisotropic Lennard-Jones interaction potentials, the relation of the interference angle with the factors, including experimental temperature, partner, and rotational quantum number, are obtained. The changing tendencies with them are discussed. This theoretical model is important to understanding and performing this kind of experiment.
文摘The key to narrow-band interference excision in frequency domain is to determine the excision thresh- old in direct-sequence spread-spectrum （DS-SS） systems. The excision threshold is a non-linear function related to the number and the power of interference, and attempting to get the exact relation of threshold related to the number and the power of interference is almost impossible. The N-sigma algorithm determines the excision threshold using subsection function; however, the excision threshold determined by this method is not exact. A new method to determine the threshold of N-sigma algorithm is proposed. The new method modifies the scale factor N by use of the membership function. The threshold determined by this method is consecutive and smooth, and it is closer to the fact than that of the initial N-sigma algorithm. The GPS signal and single-tone （CW） interference （that is, typical narrow-band interference） are implemented in the simulation, and the results are presented to demonstrate the validity of the new algorithm.
文摘Here we refer the native language to Chinese and the second language to English especially college English. According to linguistic study, there are certain native language interferences in secondlanguage acquisition when one is learning the second language,i. e. when a Chinese is learningEnglish, due to the influence of mother tongue which is habitually applied in learning the second language, his pronounciation, his grammar and his vocabulary are quite likely influencedor interfered by his native language or his dialect. Unfortunately, we did find certain first language interferences in our English teaching and learning processes on various items or subjects.
基金Project supported by the National Natural Science Foundation of China （Grant No 10374040）,
文摘Collisional quantum interference （CQI） on the intramolecular rotational energy transfer is observed in an experiment with a static cell, and the integral interference angles are measured. To obtain more accurate information, an experiment with a molecular beam is carried out, and thereby the relationship between the differential interference angle and the scattering angle is obtained. Based on the first-Born approximation of time-dependent perturbation theory, the theoretical model of CQI is developed in an atom-diatom system in the condition of the molecular beam, with the long-range interaction potential taken into account. The method of measuring correctly the differential interference angle is presented. The tendencies of the differential interference angle changing with the impact parameter and rel- ative velocity are discussed. The theoretical model presented here is important for understanding or performing the experiment in the molecular beam.
基金Project supported by the National Natural Science Foundation of China (Grant No 10374040)the Fund of the Educational Department of Liaoning Province, China (Grant No 20060347)
文摘To study theoretically the relationship between the differential interference angle and the scattering angle in collisional quantum interference （CQI）, we have investigated the differential interference angle of the atom-diatomic [case（a）] molecule system in detail. For the 2∏ electronic state in Hund＇s case （a）, the degree of the differential interference is also discussed. The differential interference angles of NO（X^2∏） are calculated quantitatively for the rotational energy transfer in Hund＇s case （a） induced by collision with He, Ne and Ar atoms. The method to calculate the differential interference angle is presented. Several factors that affect the differential interference angle are investigated. Finally the variation of the differential interference angle with the impact parameter and relative velocity is discussed.
文摘This letter presents two preprocessing techniques for narrow-band interference （NBI） rejection in Time- Division-Duplex （TDD） CDMA systems. In the proposed methods, at the transmitter, by using Karhaunen-Loeve Transform and Discrete Fourier Transform, the transmitted power is set to zero in the directions of the eigenvectors that will be severely contaminated by NBI; and therefore less part of the transmitted energy will be polluted by NBI in channel. The processing is transferred from receiver to transmitter, and thus the complexity of the receiver is significantly reduced. It is assumed that channel state information can be estimated at the transmitter because in symmetric TDD systems each receiver in turn also acts as a transmitter.
基金Project supported by the Research Foundation of Department of Education of Liaoning Province (Grant No 20060347)the NNSFC (Grant No 10374040)
文摘Collisional quantum interference （CQI） in the intramolecular rotational energy transfer was observed in experiment by Sha and co-workers. The interference angle, which measuring the degree of the coherence, were measured in the experiment of the static cell. Based on the first Born approximation of time dependent perturbation theory, taking into accounts the anisotropic Lennard-Jones interaction potentials, this paper describes the theoretical model of CQI in intramolecular rotational energy transfer in an atom-diatom collision system. In the model, the differential interference angle for the experiment of the molecular beam is calculated, the changing tendencies of the differential interference angle with the impact parameter and collision partners are obtained. This theoretical model is important for understanding or performing this kind of experiments.
基金supported by the National Natural Science Foundation of China under Grant No. 61201143the Scientific Research Foundation for Introduced Talent of Nanjing University of Aeronautics and Astronautics under Grant No. 56YAH13029
文摘Cognitive Radio （CR） can use the fre- quency band allocated to a Primary User （PU） on the premise that it will prevent significant of avoiding causing great interference to the PU. In this paper, we consider a wideband CR system where the Secondary User （SU） mini- raises its interference to the PU by jointly al- locating the optimal sensing threshold and sub- carrier power. A multi-parameter optimization problem is formulated to obtain the joint opt- imal allocation by alternating direction opti- mization, which minimises the total interfer- ence to the PU over all of the subcarriers sub- ject to the constraints on the throughput, Bit Error Rate （BER） and maximal total power of the SU, the subcarrier rate and interference power of the PU, and the false alarm and mis- detection probabilities of each subcarrier. The simulation results show that the proposed joint allocation algorithm can achieve the desired mitigation on the interference to the PU at the different subcarrier gains.
基金the National Key Research and Development Program of China(No.2018YFB 1107600)。
文摘As for ultra-precision grinding of difficult-to-process thin-walled complex components with ball-end grinding wheels,interference is easy to occur.According to screw theory and grinding kinematics,a mathematical model is established to investigate the interference and grinding characteristics of the ball-end wheel.The relationship between grinding wheel inclination angle,C axis rotation angle,grinding position angle and grinding wheel wear are analyzed.As the grinding wheel inclination angle increases,the C axis rotatable range decreases and the grinding position angle increases.The grinding position angle and wheel radius wear show a negative correlation with the C axis rotation angle.Therefore,a trajectory planning criteria for increasing grinding speed as much as possible under the premise of avoiding interference is proposed to design the grinding trajectory.Then grinding point distribution on the ball-end wheel is calculated,and the grinding characteristics,grinding speed and maximum undeformed chip thickness,are investigated.Finally,a complex structural component can be ground without interference,and surface roughness and profile accuracy are improved to 40.2 nm and 0.399 lm,compared with 556 nm and 3.427 lm before ultra-precision grinding.The mathematical model can provide theoretical guidance for the analysis of interference and grinding characteristics in complex components grinding to improve its grinding quality.
基金supported by the National High Technology ResearchDevelopment Program of China (863 Program) (2008AA0248)
文摘For decreasing the multiple access interference of weaker signal acquisition in direct sequence spread spectrum（DSSS） systems,a new single decision algorithm is presented.The maximum value of correlation results is conventionally detected.However,there may be not only one strong peak among correlation results when the cross-correlation noise is strong enough to affect the correlation results.The proposed algorithm decreases the false alarm probability through the decision of the ratio of the maximum value and the second maximum value of the correlation results.Theoretical analysis and simulation results indicate that the proposed algorithm effectively suppresses the acquisition problem of multiple access interference in DSSS system.
基金National Natural Science Foundation of China(61973037)National 173 Program Project(2019-JCJQ-ZD-324).
文摘To solve the problem of the low interference success rate of air defense missile radio fuzes due to the unified interference form of the traditional fuze interference system,an interference decision method based Q-learning algorithm is proposed.First,dividing the distance between the missile and the target into multiple states to increase the quantity of state spaces.Second,a multidimensional motion space is utilized,and the search range of which changes with the distance of the projectile,to select parameters and minimize the amount of ineffective interference parameters.The interference effect is determined by detecting whether the fuze signal disappears.Finally,a weighted reward function is used to determine the reward value based on the range state,output power,and parameter quantity information of the interference form.The effectiveness of the proposed method in selecting the range of motion space parameters and designing the discrimination degree of the reward function has been verified through offline experiments involving full-range missile rendezvous.The optimal interference form for each distance state has been obtained.Compared with the single-interference decision method,the proposed decision method can effectively improve the success rate of interference.
基金Supported by the National Natural Science Foundation of China(52275032)the Natural Science Foundation of Hebei Province(E2022203077)+1 种基金the Hebei Provincial Science and Technology Plan(22371801D)the Hebei Provincial Science and Technology Research and Development Program-Central Guidance for Local Science and Technology Development Fund(246Z1818G).
文摘Pointing mechanism is widely used in aerospace field,and its pointing accuracy and stability have high requirements.The pointing mechanism will be affected by external interference when it works.In order to eliminate the impact of interference forces on the output accuracy of the mechanism,firstly,this paper proposes a design method for highprecision pointing mechanisms based on interference separation,aiming at the high-precision pointing requirements of pointing mechanisms.Based on the screw theory,a synthesis method for inner compensation mechanisms has been proposed.And a new type of double-layer parallel mechanism has been designed to compensate for interference forces.Then,the kinematics and dynamics of the mechanism are carried out.An evaluation index for compensating external interference forces is proposed.The interference compensation analysis is conducted for the pointing mechanism.The correctness of the proposed interference force compensation coefficient is verified.Finally,in order to find the optimal solution for the workspace and interference force compensation coefficient of the pointing mechanism,multi-objective optimization design of the structural parameters of the mechanism was carried out based on the particle swarm optimization algorithm.This provides a theoretical basis for the prototype design of the subsequent double-layer parallel mechanism.This double-layer parallel mechanism combines the advantages of large load-bearing capacity,large workspace,and high output accuracy.It can be better applied in the aerospace field where high-precision pointing and force interference compensation are integrated.
基金Supported by National Defense Basic Scientific Research Project(A222013)High Quality CNC Machine Tool and Basic Manufacturing Equipment Scientific Major Project(2012ZX04010-061)
文摘A high-precision method of detecting motion straightness was proposed based on the prin- ciple of plane mirror interference after analyzing the motion straightness error of a linear stage. De- tection experiments were carried out and the motion straightness errors were separated by the linear regression method. Finally, linear measurement uncertainty of the detection method was estimated. The results showed that this detection method was simple and accurate, and was especially suitable for precision detection of motion straightness error in the small travel movement of ultra-precision machining.
文摘A novel communication receiver which uses lapped transform(LT) incorporating modified median filter(MMF) algorithm was designed for narrow band interference(NBI) excision.Comparing to traditional Fourier Transform,LT has longer basis vectors,less spectral leakage,thus better frequency resolution.The LT domain MMF algorithm takes full advantages of the direct sequence spread spectrum signal,as well as the characteristics of LT,performs the transform domain filtering twice.The first filtering locates the position of interference and mitigates most of them.The second filtering is performed in a small neighborhood of the located interference.So LT domain MMF algorithm can completely mitigate the interference without distorting the desired signal.The simulation results demonstrate the improved BER(Bit Error Rate)performance and increased robustness of our receiver.
