Currently, the selection of receiving traces in geometry design is mostly based on the horizontal layered medium hypothesis, which is unable to meet survey requirements in a complex area. This paper estimates the opti...Currently, the selection of receiving traces in geometry design is mostly based on the horizontal layered medium hypothesis, which is unable to meet survey requirements in a complex area. This paper estimates the optimal number of receiving traces in field geometry using a numerical simulation based on a field test conducted in previous research (Zhu et al., 2011). A mathematical model is established for total energy and average efficiency energy using fixed trace spacing and optimal receiving traces are estimated. Seismic data acquired in a complex work area are used to verify the correctness of the proposed method. Results of model data calculations and actual data processing show that results are in agreement. This indicates that the proposed method is reasonable, correct, sufficiently scientific, and can be regarded as a novel method for use in seismic geometry design in complex geological regions.展开更多
Northeast China is a unique place to study intra-plate volcanism. We analyzed P-wave receiver function data recorded by 111 permanent broadband seismic stations in Northeast China. The results show that the crustal th...Northeast China is a unique place to study intra-plate volcanism. We analyzed P-wave receiver function data recorded by 111 permanent broadband seismic stations in Northeast China. The results show that the crustal thickness varies from 27.9 km beneath the eastern flank of the Songliao Basin to 40.7 km beneath the Great Xing'an Range region. The large depth variations of the Moho can be largely but not completely explained by surface topography. The residual Moho depth calculated based on the Airy's isostasy model indicates that the Moho is dynamically uplifted by 〈3 km beneath the eastern flank of the Songliao Basin and the Changbaishan region. We suggest that a mantle upwelling, which has been proposed by several recent seismic studies, might have caused the uplift.展开更多
Hyperthyroidism refers to a clinical state that results from inappropriately hight hyroid hormone levels in the tissues;.Ⅰ-131 therapy plays a critical role and provides a remarkable curative effect in targeting thyr...Hyperthyroidism refers to a clinical state that results from inappropriately hight hyroid hormone levels in the tissues;.Ⅰ-131 therapy plays a critical role and provides a remarkable curative effect in targeting thyroid diseases. Thyroid cells can take up isotope I-131, which emits not only beta rays but also展开更多
Drug dependence is a serious global health problem.To assist individuals with drug addiction,China alone has established 678 Compulsory Detoxification Detention Centers (CDDCs) that treat over300,000i ndividuals who...Drug dependence is a serious global health problem.To assist individuals with drug addiction,China alone has established 678 Compulsory Detoxification Detention Centers (CDDCs) that treat over300,000i ndividuals who are required by national law to receive compulsory treatment;because community-based outpatient treatment failed.展开更多
To address the problem that it is difficult to detect an intermediate frequency(IF)signal at the receiving end of a communication system under extremely low signal-to-noise ratio(SNR)conditions,we propose a stochastic...To address the problem that it is difficult to detect an intermediate frequency(IF)signal at the receiving end of a communication system under extremely low signal-to-noise ratio(SNR)conditions,we propose a stochastic resonance(SR)-enhanced sine-signal detection method based on the sign function.By analyzing the SR mechanism of the sine signal and combining it with the characteristics of a dual-sequence frequency-hopping(DSFH)receiver,a periodic stationary solution of the Fokker-Planck equation(FPE)with a time parameter is obtained.The extreme point of the sine signal is selected as the decision time,and the force law of the electromagnetic particles is analyzed.A receiving structure based on the sign function is proposed to maximize the output difference of the system,and the value condition of the sign function is determined.In order to further improve the detection performance,in combination with the central-limit theorem,the sampling points are averaged N times,and the signal-detection problem is transformed into a hypothesis-testing problem under a Gaussian distribution.The theoretical analysis and simulation experiment results confirm that when N is 100 and the SNR is greater than 20 dB,the bit-error ratio(BER)is less than 1.5×10^(-2) under conditions in which the signal conforms to the optimal SR parameters.展开更多
In recent years,the semi-airborne transient electromagnetic method(SATEM)has been rapidly developed in China.Based on the theoretical development of the long grounding wire source transient electromagnetic method,the ...In recent years,the semi-airborne transient electromagnetic method(SATEM)has been rapidly developed in China.Based on the theoretical development of the long grounding wire source transient electromagnetic method,the unmanned aerial vehicle is equipped with the receiving coil to collect the electromagnetic response data at high altitude,making the TEM no longer affected by the terrain and greatly improving the actual working efficiency.However,its flight altitude has not been concerned for a long time.It is generally believed that the change of flight altitude only affects the amplitude of the received response.However,under special circumstances,the electromagnetic response data received at different flight altitudes in the near and far regions may lose the characteristic information of the target geological body.This paper simulates the low resistance thin layer model and analyzes the electromagnetic responses of different receiving heights under different transceiver distances.The results show that in the near area,when the flight altitude is higher than 30 meters or more,the received electromagnetic response will lose the information of the shallow lowresistance thin layer,while in the far area,the change of flight altitude has no obvious influence on the characteristic electromagnetic response information of the received geological body.展开更多
A novel technique based on sub-wavelength plasma structure effects on enhancement of RF communication signals on a receiving antenna is carried out in this paper in laboratory experiments and analyzed by corresponding...A novel technique based on sub-wavelength plasma structure effects on enhancement of RF communication signals on a receiving antenna is carried out in this paper in laboratory experiments and analyzed by corresponding numerical simulations.Considerable intensification on receiving signal gain up to -10 d B in comparison with that without the plasma modulation is observed experimentally in -1 GHz RF band,with an effective enhancement bandwidth of -340 MHz and the fractional bandwidth of -34%.Then,the optimal modulation parameters of plasma are further studied by a numerical simulation.It is shown that the number density,the layer thickness,and the collision frequency of the plasma,as well as the relative distance between the plasma layer and antenna synergistically affect the modulation.Compared to the metallic antenna with the same overall dimension,the modulated antenna covered by the subwavelength plasma structure features higher receiving efficiency and lower radar cross section in the studied RF band.The mechanism of the reception enhancement is further revealed by analyzing characteristics of electromagnetic scattering and electric field distribution in the subwavelength plasma layer.The results then exhibit scientific significance and application potential of sub-wavelength plasma modulation on compact receiving antennas with higher performance and better feature of radar stealth.展开更多
The influence of the selection of receiving slits and the use of standard samples with random orientation on the result of quantitative texture analysis was tested and discussed. The result proves that it will improve...The influence of the selection of receiving slits and the use of standard samples with random orientation on the result of quantitative texture analysis was tested and discussed. The result proves that it will improve the precision of the analysis to use proper slits and a randomly oriented standard sample. A simple method was given to interpolate the correction curves of random intensities.展开更多
The influence of close-up feed strategies on growth performance and dietary NE in light-weight feedlot steers during a 56 d receiving period was evaluated. Dietary treatments were formulated to meet the average metabo...The influence of close-up feed strategies on growth performance and dietary NE in light-weight feedlot steers during a 56 d receiving period was evaluated. Dietary treatments were formulated to meet the average metabolizable amino acid requirements of calves during 1) the initial 7 d;2) the initial 14 d;and 3) the initial 21 d following arrival into the feedlot, assuming average interval DMI of 2.8, 3.0, and 3.6 kg/d, respectively. Thereafter, all steers received dietary treatment 3. Fish meal was the source of supplemental protein. One hundred eight medium-framed crossbred steers (168.4 ± 5.0 kg) were blocked by weight and assigned to 18 pen groups (6 steers per pen). P-value (≤0.10) was considered as statistically significant. Daily weight gain (linear effect, P = 0.09) and gain efficiency (linear effect, P = 0.08) decreased as the close-up interval increased. DMI was not influenced by feeding program (P = 0.46). The ratio of observed to expected dietary NEm (linear effect P = 0.06) and NEg (linear effect, P = 0.05) decreased as length of close-up interval increased. Morbidity was low (18%) and not affected (P > 0.40) by dietary treatments. It is concluded that the addition of a close-up diet formulated to meet the metabolizable amino acid requirements of shipping stressed calves during the initial 7 d in the feedlot, when feed intakes are comparatively low, will have long-term beneficial effect on cattle growth performance and dietary NE.展开更多
Taking 13 water-receiving areas on the East Route of the South-to-North Water Diversion Project(ERSNWDP)in Shandong Province as the study area,and comparing it with Jiangsu Province on the ERSNWDP and the Middle Route...Taking 13 water-receiving areas on the East Route of the South-to-North Water Diversion Project(ERSNWDP)in Shandong Province as the study area,and comparing it with Jiangsu Province on the ERSNWDP and the Middle Route of the South-to-North(MRSNWDP),the current water-saving potential of the water-receiving areas within the municipalities of Shandong was analyzed.Different water-saving scenarios were constructed and analyzed with key water-saving indexes in various industries.These indexes include the effective utilization coefficient of farmland irrigation water,total water consumption of industrial sectors with an added value of over 10000 RMB,average leakage rate of the urban public water supply pipe network and the penetration rate of water-saving appliances.Based on the scenarios,comprehensive water-saving potential of the 13 water-receiving area cities was calculated.The results show that the water-saving potential of the study area is at a relative high level.However,some cities still have a certain amount of water-saving potential for agriculture and industry to be elevated.Under the recommended water-saving scenario,the water-saving potential is 1.134 billion m3,accounting for 5.33%of the current total water consumption,of which 460 million m3 is in agriculture,600 million m3 in industry,is and 74.20 million m3 in urban domestic sector.Comprehensive water-saving measures for the study area were proposed from the aspects of agricultural,industrial and domestic water uses.Agricultural and industrial water saving are more significant.The major cities for agricultural water saving include Jining City,Heze City,Weifang City and Jinan City;the focus cities of industrial water saving mainly include Weihai City,Jining City and Qingdao City and etc.;the key water-saving areas for urban use mainly include Zaozhuang City,Jining City and Heze City.展开更多
Designing an Ethernet switch that can assure normal interaction of protocol packets between switches in a network environment of massive traffic is an important matter. Taking the L3 Ethernet switch based on Applicati...Designing an Ethernet switch that can assure normal interaction of protocol packets between switches in a network environment of massive traffic is an important matter. Taking the L3 Ethernet switch based on Application Specific Integrated Circuit (ASIC) as an example,this article analyzes several typical issues about packet receiving and sending by the CPU in a multi-progress environment,including CPU load,software and hardware queue settings,and communication mechanism between CPU and the switch chip. This article gives solutions to these issues mentioned above. The solutions are applicable to Network Processor (NP) issues as well.展开更多
I feel that this award was not made to me as a man,but to mywork—a life s work in the agony and sweat of the human spirit,not for glory and least of all for profit,but to create out of thematerials of the human spiri...I feel that this award was not made to me as a man,but to mywork—a life s work in the agony and sweat of the human spirit,not for glory and least of all for profit,but to create out of thematerials of the human spirit something which did not exist before,sothis award is only mine in trust.It will not be difficult to fred a dedi-cation for the money part of it commensurate with the purpose andsignificance of its origin.But I would like to do the same with the ac-claim too,by using this moment as a ...展开更多
This paper presents the design,fabrication,packaging,and characterization of a high-performance CMUT array.The array,which features rectangular cells fabricated using a sacrificial release process,achieves a receiving...This paper presents the design,fabrication,packaging,and characterization of a high-performance CMUT array.The array,which features rectangular cells fabricated using a sacrificial release process,achieves a receiving sensitivity of-231.44 d B(re:1 V/μPa)with a 40 d B gain.Notably,the CMUT array exhibits a minimal sensitivity variation of just 0.87 d B across a temperature range of 0 to 60°C.Furthermore,the output voltage non-linearity at 1 k Hz is approximately 0.44%.These test results demonstrate that the reception performance of the 67-element CMUT array is superior to that of commercial transducers.The high performance and compact design of this CMUT array underscore its significant commercial potential for hydrophone applications.展开更多
The South China Block(SCB)was formed through the Neoproterozoic amalgamation of the Yangtze Block(YB),the Cathaysia Block(CB),and the accreted components of the Jiangnan orogenic belt(JNO),it is bounded by the Jiangs...The South China Block(SCB)was formed through the Neoproterozoic amalgamation of the Yangtze Block(YB),the Cathaysia Block(CB),and the accreted components of the Jiangnan orogenic belt(JNO),it is bounded by the Jiangshan–Shaoxing–Pingxiang fault(JSPF)and the Jiujiang–Shitai–Jishou fault(JSJF)(Yao et al.,2019).The SCB has undergone a series of complex geological events,including Paleozoic orogeny,Mesozoic collisions with the North China Craton(NCC)and the Indochina Block,as well as the intracontinental orogeny,leading to extensive lithospheric modifications and magmatic activities(Zhang H J et al.,2023;Fig.1).展开更多
Unmanned aerial vehicles(UAVs)may be subjected to unintentional radio frequency interference(RFI)or hostile jamming attack which will lead to fail to track global navigation satellite system(GNSS)signals.Therefore,the...Unmanned aerial vehicles(UAVs)may be subjected to unintentional radio frequency interference(RFI)or hostile jamming attack which will lead to fail to track global navigation satellite system(GNSS)signals.Therefore,the simultaneous realization of anti-jamming and high-precision carrier phase difference positioning becomes a dilemmatic problem.In this paper,a distortionless phase digital beamforming(DBF)algorithm with self-calibration antenna arrays is proposed,which enables to obtain distortionless carrier phase while suppressing jamming.Additionally,architecture of high precision Beidou receiver based on anti-jamming antenna arrays is proposed.Finally,the performance of the algorithm is evaluated,including antenna calibration accuracy,carrier phase distortionless accuracy,and carrier phase measurement accuracy without jamming.Meanwhile,the maximal jamming to signal ratio(JSR)and real time kinematic(RTK)positioning accuracy under wideband jamming are also investigated.The experimental results based on the real-life Beidou signals show that the proposed method has an excellent performance for precise relative positioning under jamming when compared with other anti-jamming methods.展开更多
Indoor localization systems are crucial in addressing the limitations of traditional global positioning system(GPS)in indoor environments due to signal attenuation issues.As complex indoor spaces become more sophistic...Indoor localization systems are crucial in addressing the limitations of traditional global positioning system(GPS)in indoor environments due to signal attenuation issues.As complex indoor spaces become more sophisticated,indoor localization systems become essential for improving user experience,safety,and operational efficiency.Indoor localization methods based on Wi-Fi fingerprints require a high-density location fingerprint database,but this can increase the computational burden in the online phase.Bayesian networks,which integrate prior knowledge or domain expertise,are an effective solution for accurately determining indoor user locations.These networks use probabilistic reasoning to model relationships among various localization parameters for indoor environments that are challenging to navigate.This article proposes an adaptive Bayesian model for multi-floor environments based on fingerprinting techniques to minimize errors in estimating user location.The proposed system is an off-the-shelf solution that uses existing Wi-Fi infrastructures to estimate user’s location.It operates in both online and offline phases.In the offline phase,a mobile device with Wi-Fi capability collects radio signals,while in the online phase,generating samples using Gibbs sampling based on the proposed Bayesian model and radio map to predict user’s location.Experimental results unequivocally showcase the superior performance of the proposed model when compared to other existing models and methods.The proposed model achieved an impressive lower average localization error,surpassing the accuracy of competing approaches.Notably,this noteworthy achievement was attained with minimal reliance on reference points,underscoring the efficiency and efficacy of the proposed model in accurately estimating user locations in indoor environments.展开更多
In recent years,propelled by the rapid iterative advancements in digital imaging technology and the semiconductor industry,encompassing microelectronic design,manufacturing,packaging,and testing,time-of-flight(ToF)-ba...In recent years,propelled by the rapid iterative advancements in digital imaging technology and the semiconductor industry,encompassing microelectronic design,manufacturing,packaging,and testing,time-of-flight(ToF)-based imaging systems for acquiring depth information have garnered considerable attention from both academia and industry.This technology has emerged as a focal point of research within the realm of 3D imaging.Owing to its relatively straightforward principles and exceptional performance,ToF technology finds extensive applications across various domains including human−computer interaction,autonomous driving,industrial inspection,medical and healthcare,augmented reality,smart homes,and 3D reconstruction,among others.Notably,the increasing maturity of ToF-based LiDAR systems is evident in current developments.This paper comprehensively reviews the fundamental principles of ToF technology and LiDAR systems,alongside recent research advancements.It elucidates the innovative aspects and technical challenges encountered in both transmitter(TX)and receiver(RX),providing detailed discussions on corresponding solutions.Furthermore,the paper explores prospective avenues for future research,offering valuable insights for subsequent investigations.展开更多
The Shanghai Tianma 65 m radio telescope(TMRT)is a large,fully rotatable radio telescope with multiple scientific purposes.The main body of the telescope and four low-frequency receiving systems,including L,C,and S/X ...The Shanghai Tianma 65 m radio telescope(TMRT)is a large,fully rotatable radio telescope with multiple scientific purposes.The main body of the telescope and four low-frequency receiving systems,including L,C,and S/X bands,were completed between 2008 and 2012.From 2013 to 2017,four high-frequency receiving systems,including Ku,K,Ka,and Q bands,were constructed and their performance was comprehensively tested.There are three main innovations.(1)A fully movable large radio telescope system with advanced performance and complete functions has been built.(2)An advanced,reliable main reflector adjustment system has been completed,overcoming gravity deformation and creating a large antenna with a main reflective surface accuracy of 0.28 mm(root mean square)for any elevation.(3)Five innovative technologies have been developed to achieve high-precision pointing in any direction within 3″.The TMRT has made a crucial contribution to the orbital measurement and positioning of China’s lunar and deep space probes.Significantly enhancing China's ability to participate in international VLBI observations and radio astronomy,this has facilitated a series of achievements in observational radio astronomical research,in areas such as VLBI,spectral lines,and pulsars.展开更多
Aiming at evaluating and predicting rapidly and accurately a high sensitivity receiver’s adaptability in complex electromagnetic environments,a novel testing and prediction method based on dual-channel multi-frequenc...Aiming at evaluating and predicting rapidly and accurately a high sensitivity receiver’s adaptability in complex electromagnetic environments,a novel testing and prediction method based on dual-channel multi-frequency is proposed to improve the traditional two-tone test.Firstly,two signal generators are used to generate signals at the radio frequency(RF)by frequency scanning,and then a rapid measurement at the intermediate frequency(IF)output port is carried out to obtain a huge amount of sample data for the subsequent analysis.Secondly,the IF output response data are modeled and analyzed to construct the linear and nonlinear response constraint equations in the frequency domain and prediction models in the power domain,which provide the theoretical criteria for interpreting and predicting electromagnetic susceptibility(EMS)of the receiver.An experiment performed on a radar receiver confirms the reliability of the method proposed in this paper.It shows that the interference of each harmonic frequency and each order to the receiver can be identified and predicted with the sensitivity model.Based on this,fast and comprehensive evaluation and prediction of the receiver’s EMS in complex environment can be efficiently realized.展开更多
基金supported by the National Natural Science Foundation of China(No.41304115)National Key S&T Special Projects(No.2016ZX050 24001-003)+2 种基金Open Fund for Sichuan Province Key Laboratory of Natural Gas Geology(No.2015trqdz02)the Research Project,CNPC(No.2016A-33)"Young and Middle-aged Key Teachers"Training Program in Southwest Petroleum University
文摘Currently, the selection of receiving traces in geometry design is mostly based on the horizontal layered medium hypothesis, which is unable to meet survey requirements in a complex area. This paper estimates the optimal number of receiving traces in field geometry using a numerical simulation based on a field test conducted in previous research (Zhu et al., 2011). A mathematical model is established for total energy and average efficiency energy using fixed trace spacing and optimal receiving traces are estimated. Seismic data acquired in a complex work area are used to verify the correctness of the proposed method. Results of model data calculations and actual data processing show that results are in agreement. This indicates that the proposed method is reasonable, correct, sufficiently scientific, and can be regarded as a novel method for use in seismic geometry design in complex geological regions.
文摘Northeast China is a unique place to study intra-plate volcanism. We analyzed P-wave receiver function data recorded by 111 permanent broadband seismic stations in Northeast China. The results show that the crustal thickness varies from 27.9 km beneath the eastern flank of the Songliao Basin to 40.7 km beneath the Great Xing'an Range region. The large depth variations of the Moho can be largely but not completely explained by surface topography. The residual Moho depth calculated based on the Airy's isostasy model indicates that the Moho is dynamically uplifted by 〈3 km beneath the eastern flank of the Songliao Basin and the Changbaishan region. We suggest that a mantle upwelling, which has been proposed by several recent seismic studies, might have caused the uplift.
基金supported by a fund from the Key Project of Natural Science Foundation of Tianjin [16JCZDJC36100]Medical and Health Technology Innovation Project of the Chinese Academy of Medical Sciences [2017-I2M-1-016]+2 种基金Fundamental Research Funds for the Central Universities [3332018116]PUMC Youth Fund [3332015101]Fundamental Research Funds for CAMS&PUMC [2016ZX310074]
文摘Hyperthyroidism refers to a clinical state that results from inappropriately hight hyroid hormone levels in the tissues;.Ⅰ-131 therapy plays a critical role and provides a remarkable curative effect in targeting thyroid diseases. Thyroid cells can take up isotope I-131, which emits not only beta rays but also
基金supported by the National Natural Science Foundation of China [No.71774175]
文摘Drug dependence is a serious global health problem.To assist individuals with drug addiction,China alone has established 678 Compulsory Detoxification Detention Centers (CDDCs) that treat over300,000i ndividuals who are required by national law to receive compulsory treatment;because community-based outpatient treatment failed.
基金Project supported by the Natural Science Foundation of Hebei Province of China(Grant Nos.F2019506031,F2019506037,and F2020506036)the Frontier Innovation Program of Army Engineering University(Grant No.KYSZJQZL2005)the Basic Frontier Science and Technology Innovation Program of Army Engineering University(Grant No.KYSZJQZL2020).
文摘To address the problem that it is difficult to detect an intermediate frequency(IF)signal at the receiving end of a communication system under extremely low signal-to-noise ratio(SNR)conditions,we propose a stochastic resonance(SR)-enhanced sine-signal detection method based on the sign function.By analyzing the SR mechanism of the sine signal and combining it with the characteristics of a dual-sequence frequency-hopping(DSFH)receiver,a periodic stationary solution of the Fokker-Planck equation(FPE)with a time parameter is obtained.The extreme point of the sine signal is selected as the decision time,and the force law of the electromagnetic particles is analyzed.A receiving structure based on the sign function is proposed to maximize the output difference of the system,and the value condition of the sign function is determined.In order to further improve the detection performance,in combination with the central-limit theorem,the sampling points are averaged N times,and the signal-detection problem is transformed into a hypothesis-testing problem under a Gaussian distribution.The theoretical analysis and simulation experiment results confirm that when N is 100 and the SNR is greater than 20 dB,the bit-error ratio(BER)is less than 1.5×10^(-2) under conditions in which the signal conforms to the optimal SR parameters.
基金sponsored by National Natural Resources Foundation program(SKLGP2020K023).
文摘In recent years,the semi-airborne transient electromagnetic method(SATEM)has been rapidly developed in China.Based on the theoretical development of the long grounding wire source transient electromagnetic method,the unmanned aerial vehicle is equipped with the receiving coil to collect the electromagnetic response data at high altitude,making the TEM no longer affected by the terrain and greatly improving the actual working efficiency.However,its flight altitude has not been concerned for a long time.It is generally believed that the change of flight altitude only affects the amplitude of the received response.However,under special circumstances,the electromagnetic response data received at different flight altitudes in the near and far regions may lose the characteristic information of the target geological body.This paper simulates the low resistance thin layer model and analyzes the electromagnetic responses of different receiving heights under different transceiver distances.The results show that in the near area,when the flight altitude is higher than 30 meters or more,the received electromagnetic response will lose the information of the shallow lowresistance thin layer,while in the far area,the change of flight altitude has no obvious influence on the characteristic electromagnetic response information of the received geological body.
基金supported by National Natural Science Foundation of China(Nos.51577044 and 11605035)
文摘A novel technique based on sub-wavelength plasma structure effects on enhancement of RF communication signals on a receiving antenna is carried out in this paper in laboratory experiments and analyzed by corresponding numerical simulations.Considerable intensification on receiving signal gain up to -10 d B in comparison with that without the plasma modulation is observed experimentally in -1 GHz RF band,with an effective enhancement bandwidth of -340 MHz and the fractional bandwidth of -34%.Then,the optimal modulation parameters of plasma are further studied by a numerical simulation.It is shown that the number density,the layer thickness,and the collision frequency of the plasma,as well as the relative distance between the plasma layer and antenna synergistically affect the modulation.Compared to the metallic antenna with the same overall dimension,the modulated antenna covered by the subwavelength plasma structure features higher receiving efficiency and lower radar cross section in the studied RF band.The mechanism of the reception enhancement is further revealed by analyzing characteristics of electromagnetic scattering and electric field distribution in the subwavelength plasma layer.The results then exhibit scientific significance and application potential of sub-wavelength plasma modulation on compact receiving antennas with higher performance and better feature of radar stealth.
文摘The influence of the selection of receiving slits and the use of standard samples with random orientation on the result of quantitative texture analysis was tested and discussed. The result proves that it will improve the precision of the analysis to use proper slits and a randomly oriented standard sample. A simple method was given to interpolate the correction curves of random intensities.
文摘The influence of close-up feed strategies on growth performance and dietary NE in light-weight feedlot steers during a 56 d receiving period was evaluated. Dietary treatments were formulated to meet the average metabolizable amino acid requirements of calves during 1) the initial 7 d;2) the initial 14 d;and 3) the initial 21 d following arrival into the feedlot, assuming average interval DMI of 2.8, 3.0, and 3.6 kg/d, respectively. Thereafter, all steers received dietary treatment 3. Fish meal was the source of supplemental protein. One hundred eight medium-framed crossbred steers (168.4 ± 5.0 kg) were blocked by weight and assigned to 18 pen groups (6 steers per pen). P-value (≤0.10) was considered as statistically significant. Daily weight gain (linear effect, P = 0.09) and gain efficiency (linear effect, P = 0.08) decreased as the close-up interval increased. DMI was not influenced by feeding program (P = 0.46). The ratio of observed to expected dietary NEm (linear effect P = 0.06) and NEg (linear effect, P = 0.05) decreased as length of close-up interval increased. Morbidity was low (18%) and not affected (P > 0.40) by dietary treatments. It is concluded that the addition of a close-up diet formulated to meet the metabolizable amino acid requirements of shipping stressed calves during the initial 7 d in the feedlot, when feed intakes are comparatively low, will have long-term beneficial effect on cattle growth performance and dietary NE.
基金We would like to give our thanks to Water Resources Department of Shandong Province and Water Resources Research Institute of Shandong Province for their help.
文摘Taking 13 water-receiving areas on the East Route of the South-to-North Water Diversion Project(ERSNWDP)in Shandong Province as the study area,and comparing it with Jiangsu Province on the ERSNWDP and the Middle Route of the South-to-North(MRSNWDP),the current water-saving potential of the water-receiving areas within the municipalities of Shandong was analyzed.Different water-saving scenarios were constructed and analyzed with key water-saving indexes in various industries.These indexes include the effective utilization coefficient of farmland irrigation water,total water consumption of industrial sectors with an added value of over 10000 RMB,average leakage rate of the urban public water supply pipe network and the penetration rate of water-saving appliances.Based on the scenarios,comprehensive water-saving potential of the 13 water-receiving area cities was calculated.The results show that the water-saving potential of the study area is at a relative high level.However,some cities still have a certain amount of water-saving potential for agriculture and industry to be elevated.Under the recommended water-saving scenario,the water-saving potential is 1.134 billion m3,accounting for 5.33%of the current total water consumption,of which 460 million m3 is in agriculture,600 million m3 in industry,is and 74.20 million m3 in urban domestic sector.Comprehensive water-saving measures for the study area were proposed from the aspects of agricultural,industrial and domestic water uses.Agricultural and industrial water saving are more significant.The major cities for agricultural water saving include Jining City,Heze City,Weifang City and Jinan City;the focus cities of industrial water saving mainly include Weihai City,Jining City and Qingdao City and etc.;the key water-saving areas for urban use mainly include Zaozhuang City,Jining City and Heze City.
文摘Designing an Ethernet switch that can assure normal interaction of protocol packets between switches in a network environment of massive traffic is an important matter. Taking the L3 Ethernet switch based on Application Specific Integrated Circuit (ASIC) as an example,this article analyzes several typical issues about packet receiving and sending by the CPU in a multi-progress environment,including CPU load,software and hardware queue settings,and communication mechanism between CPU and the switch chip. This article gives solutions to these issues mentioned above. The solutions are applicable to Network Processor (NP) issues as well.
文摘I feel that this award was not made to me as a man,but to mywork—a life s work in the agony and sweat of the human spirit,not for glory and least of all for profit,but to create out of thematerials of the human spirit something which did not exist before,sothis award is only mine in trust.It will not be difficult to fred a dedi-cation for the money part of it commensurate with the purpose andsignificance of its origin.But I would like to do the same with the ac-claim too,by using this moment as a ...
基金supported in part by the National Natural Science Foundation of China under Grant 61927807,62320106011,and 62304208China Postdoctoral Science Foundation under Grant 2023M733277 and2024T170848。
文摘This paper presents the design,fabrication,packaging,and characterization of a high-performance CMUT array.The array,which features rectangular cells fabricated using a sacrificial release process,achieves a receiving sensitivity of-231.44 d B(re:1 V/μPa)with a 40 d B gain.Notably,the CMUT array exhibits a minimal sensitivity variation of just 0.87 d B across a temperature range of 0 to 60°C.Furthermore,the output voltage non-linearity at 1 k Hz is approximately 0.44%.These test results demonstrate that the reception performance of the 67-element CMUT array is superior to that of commercial transducers.The high performance and compact design of this CMUT array underscore its significant commercial potential for hydrophone applications.
基金jointly sponsored by the Sinoprobe Laboratory of Chinese Academy of Geological Sciences(Grant No.JKYQN202303)National Natural Science Foundation of China(Grant No.U2344220)the China Geology Survey Project(Grant Nos.DD20230008,DD20240079)。
文摘The South China Block(SCB)was formed through the Neoproterozoic amalgamation of the Yangtze Block(YB),the Cathaysia Block(CB),and the accreted components of the Jiangnan orogenic belt(JNO),it is bounded by the Jiangshan–Shaoxing–Pingxiang fault(JSPF)and the Jiujiang–Shitai–Jishou fault(JSJF)(Yao et al.,2019).The SCB has undergone a series of complex geological events,including Paleozoic orogeny,Mesozoic collisions with the North China Craton(NCC)and the Indochina Block,as well as the intracontinental orogeny,leading to extensive lithospheric modifications and magmatic activities(Zhang H J et al.,2023;Fig.1).
基金supported by the Key Research and Development Program of Science&Technology Department of Sichuan Province(2021YFG0155)the Technical Innovation Fund of Southwest China Institute of Electronic Technology(H21004.2).
文摘Unmanned aerial vehicles(UAVs)may be subjected to unintentional radio frequency interference(RFI)or hostile jamming attack which will lead to fail to track global navigation satellite system(GNSS)signals.Therefore,the simultaneous realization of anti-jamming and high-precision carrier phase difference positioning becomes a dilemmatic problem.In this paper,a distortionless phase digital beamforming(DBF)algorithm with self-calibration antenna arrays is proposed,which enables to obtain distortionless carrier phase while suppressing jamming.Additionally,architecture of high precision Beidou receiver based on anti-jamming antenna arrays is proposed.Finally,the performance of the algorithm is evaluated,including antenna calibration accuracy,carrier phase distortionless accuracy,and carrier phase measurement accuracy without jamming.Meanwhile,the maximal jamming to signal ratio(JSR)and real time kinematic(RTK)positioning accuracy under wideband jamming are also investigated.The experimental results based on the real-life Beidou signals show that the proposed method has an excellent performance for precise relative positioning under jamming when compared with other anti-jamming methods.
基金This work was supported and funded by the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University(IMSIU)(Grant Number IMSIU-RPP2023011).
文摘Indoor localization systems are crucial in addressing the limitations of traditional global positioning system(GPS)in indoor environments due to signal attenuation issues.As complex indoor spaces become more sophisticated,indoor localization systems become essential for improving user experience,safety,and operational efficiency.Indoor localization methods based on Wi-Fi fingerprints require a high-density location fingerprint database,but this can increase the computational burden in the online phase.Bayesian networks,which integrate prior knowledge or domain expertise,are an effective solution for accurately determining indoor user locations.These networks use probabilistic reasoning to model relationships among various localization parameters for indoor environments that are challenging to navigate.This article proposes an adaptive Bayesian model for multi-floor environments based on fingerprinting techniques to minimize errors in estimating user location.The proposed system is an off-the-shelf solution that uses existing Wi-Fi infrastructures to estimate user’s location.It operates in both online and offline phases.In the offline phase,a mobile device with Wi-Fi capability collects radio signals,while in the online phase,generating samples using Gibbs sampling based on the proposed Bayesian model and radio map to predict user’s location.Experimental results unequivocally showcase the superior performance of the proposed model when compared to other existing models and methods.The proposed model achieved an impressive lower average localization error,surpassing the accuracy of competing approaches.Notably,this noteworthy achievement was attained with minimal reliance on reference points,underscoring the efficiency and efficacy of the proposed model in accurately estimating user locations in indoor environments.
文摘In recent years,propelled by the rapid iterative advancements in digital imaging technology and the semiconductor industry,encompassing microelectronic design,manufacturing,packaging,and testing,time-of-flight(ToF)-based imaging systems for acquiring depth information have garnered considerable attention from both academia and industry.This technology has emerged as a focal point of research within the realm of 3D imaging.Owing to its relatively straightforward principles and exceptional performance,ToF technology finds extensive applications across various domains including human−computer interaction,autonomous driving,industrial inspection,medical and healthcare,augmented reality,smart homes,and 3D reconstruction,among others.Notably,the increasing maturity of ToF-based LiDAR systems is evident in current developments.This paper comprehensively reviews the fundamental principles of ToF technology and LiDAR systems,alongside recent research advancements.It elucidates the innovative aspects and technical challenges encountered in both transmitter(TX)and receiver(RX),providing detailed discussions on corresponding solutions.Furthermore,the paper explores prospective avenues for future research,offering valuable insights for subsequent investigations.
基金supported by National Natural Science Foundation of China(12273098).
文摘The Shanghai Tianma 65 m radio telescope(TMRT)is a large,fully rotatable radio telescope with multiple scientific purposes.The main body of the telescope and four low-frequency receiving systems,including L,C,and S/X bands,were completed between 2008 and 2012.From 2013 to 2017,four high-frequency receiving systems,including Ku,K,Ka,and Q bands,were constructed and their performance was comprehensively tested.There are three main innovations.(1)A fully movable large radio telescope system with advanced performance and complete functions has been built.(2)An advanced,reliable main reflector adjustment system has been completed,overcoming gravity deformation and creating a large antenna with a main reflective surface accuracy of 0.28 mm(root mean square)for any elevation.(3)Five innovative technologies have been developed to achieve high-precision pointing in any direction within 3″.The TMRT has made a crucial contribution to the orbital measurement and positioning of China’s lunar and deep space probes.Significantly enhancing China's ability to participate in international VLBI observations and radio astronomy,this has facilitated a series of achievements in observational radio astronomical research,in areas such as VLBI,spectral lines,and pulsars.
基金supported by the National Natural Science Foundation of China(62071473).
文摘Aiming at evaluating and predicting rapidly and accurately a high sensitivity receiver’s adaptability in complex electromagnetic environments,a novel testing and prediction method based on dual-channel multi-frequency is proposed to improve the traditional two-tone test.Firstly,two signal generators are used to generate signals at the radio frequency(RF)by frequency scanning,and then a rapid measurement at the intermediate frequency(IF)output port is carried out to obtain a huge amount of sample data for the subsequent analysis.Secondly,the IF output response data are modeled and analyzed to construct the linear and nonlinear response constraint equations in the frequency domain and prediction models in the power domain,which provide the theoretical criteria for interpreting and predicting electromagnetic susceptibility(EMS)of the receiver.An experiment performed on a radar receiver confirms the reliability of the method proposed in this paper.It shows that the interference of each harmonic frequency and each order to the receiver can be identified and predicted with the sensitivity model.Based on this,fast and comprehensive evaluation and prediction of the receiver’s EMS in complex environment can be efficiently realized.