Contrary to the other multi-carrier modulation systems, the coherent optical orthogonal frequency division multiplexing communication system with an offset quadrature amplitude modulation (CO-OFDM-OQAM) possesses inhe...Contrary to the other multi-carrier modulation systems, the coherent optical orthogonal frequency division multiplexing communication system with an offset quadrature amplitude modulation (CO-OFDM-OQAM) possesses inherent imaginary interference (IMI). This has an important impact on the channel estimation process. Currently, a variety of frequency-domain channel estimation methods have been proposed. However, there are various problems that still exist. For instance, in order to reduce the influence of IMI, it is necessary to insert more guard intervals between the training sequence and the payload, leading to the occupation of excessive spectrum resources. In order to address this problem, this work designs a high spectral efficient frequency-domain channel estimation method for the polarization-division-multiplexing CO-OFDM-OQAM systems. First, the working principle of the proposed method is described in detail. Then, its spectral efficiency, power peak-to-average ratio, and channel estimation performance are studied based on simulations. The simulation results show that the proposed method improves the spectral efficiency without worsening the power peak-to-average ratio. The channel estimation capability of this method is verified in three scenarios of long-distance transmissions, including back-to-back, 100 km, and 200 km transmissions. .展开更多
In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel mod...In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel model, the cascaded propagation loss of relay link and the cascaded probability density function(PDF) of channel fading are derived. Moreover, the theoretical performance of the UAV-based relay system, i.e., the outage probability, bit error rate(BER), and channel capacity, is also analysed and derived. Simulation results show agreement with theoretical results for the hill, mountain, and sea scenarios, indicating the accuracy of both the simulations and derivations.展开更多
This paper studied an architecture model of turbidite channel systems based on the shallow- layer high resolution 3D seismic information in the deepwater area in the Niger Delta continental slope, West Africa as a pro...This paper studied an architecture model of turbidite channel systems based on the shallow- layer high resolution 3D seismic information in the deepwater area in the Niger Delta continental slope, West Africa as a prototype model. Different types of channel systems were identified and the corresponding architecture models were established. The controlling factors, evaluation criteria and spatial distribution of different channel systems were analyzed. This study shows that turbidite channel systems of West Africa could be classified into three types; confined, semi-confined and unconfined, according to the condition of canyon and the levees on both sides. Oil one hand, along the transport direction, channel system evolves from confined to unconfined. Within channel systems, channel complexes, including two types of incised and enveloped, are the most important reservoir bodies. On the other hand, there is a channel complex evolution from incised to enveloped vertically. The geological factors exert impacts of different levels on the architecture of the turbidite channels in different sedimentary systems or even within the same system.展开更多
To reduce channel noise,fading,and inter-user interference effectively in the chaotic communication systems with multi-user,a blind channel equalization algorithm based on dual unscented Kalman filter algorithm is pro...To reduce channel noise,fading,and inter-user interference effectively in the chaotic communication systems with multi-user,a blind channel equalization algorithm based on dual unscented Kalman filter algorithm is proposed.Assuming that the coefficients of a multi-input multi-output (MIMO) channel can be described by an autoregressive model,two separate state-space representations are used for the signals and coefficients.Then two unscented Kalman filters are used to estimate chaotic signals and channel coefficients simultaneously.The simulation results indicate that the algorithm can effectively track the coefficients of the multi-path fading channel in chaotic MIMO communication systems at a fast convergence speed.展开更多
Human normal endometrium was examined in ultrathin sections.Nucleolar channel system(NCS) appeared in the endometrial epithelial cells during the early and mid secretory phase of menstrual cycle.The NCS was a hollow b...Human normal endometrium was examined in ultrathin sections.Nucleolar channel system(NCS) appeared in the endometrial epithelial cells during the early and mid secretory phase of menstrual cycle.The NCS was a hollow ball like structure of different sizes and was composed of 2 to 5 rows of tubules embedded in an amporphous matrix.On its surface there were numerous electron dense particles resembling ribosomes,It was usually located within or associated with the nucleolus,SOmetimes,it was close to the nuclear envelope or protruding out from the nucleus .On occasion,NCS with simplified structure was found in the perinuclear cytoplasm.Concepts concerning the genesis,involution and function(s) of the NCS were disussed.展开更多
This paper addresses the issues of channel estimation in a Multiple-Input/Multiple-Output (MIMO) system. Markov Chain Monte Carlo (MCMC) method is employed to jointly estimate the Channel State Information (CSI) and t...This paper addresses the issues of channel estimation in a Multiple-Input/Multiple-Output (MIMO) system. Markov Chain Monte Carlo (MCMC) method is employed to jointly estimate the Channel State Information (CSI) and the transmitted signals. The deduced algorithms can work well under circumstances of low Signal-to-Noise Ratio (SNR). Simulation results are presented to demonstrate their effectiveness.展开更多
In this paper, the effect of channel estimation errors upon the Zero Forcing (ZF) precoding Multiple Input Multiple Output Broadcast (MIMO BC) systems was studied. Based on the two kinds of Gaussian estimation error m...In this paper, the effect of channel estimation errors upon the Zero Forcing (ZF) precoding Multiple Input Multiple Output Broadcast (MIMO BC) systems was studied. Based on the two kinds of Gaussian estimation error models, the performance analysis is conducted under different power allocation strategies. Analysis and simulation show that if the covariance of channel estimation errors is independent of the received Signal to Noise Ratio (SNR), imperfect channel knowledge deteriorates the sum capacity and the Bit Error Rate (BER) performance severely. However, under the situation of orthogonal training and the Minimum Mean Square Error (MMSE) channel estimation, the sum ca- pacity and BER performance are consistent with those of the perfect Channel State Information (CSI) with only a performance degradation.展开更多
A data acquisition system (DAS) to implement high-speed, real-time and multi-channel data acquisition and store is presented. The control of the system is implemented by the combination of complex programable logic ...A data acquisition system (DAS) to implement high-speed, real-time and multi-channel data acquisition and store is presented. The control of the system is implemented by the combination of complex programable logic device (CPLD) and digital signal processing (DSP), the bulk buffer of the system is implemented by the combination of CPLD, DSP, and synchronous dynamic random access memory (SDRAM), and the data transfer is implemented by the combination of DSP, first in first out (FIFO), universal serial bus (USB) and USB hub. The system could not only work independently in single-channel mode, but also implement high-speed real-time multi-channel data acquisition system (MCDAS) by the combination of multiple single-channels. The sampling rate and data storage capacity of each channel could reach up to 100 million sampiing per second and 256 MB respectively.展开更多
Objective To determine whether formation of the nucleolar channel system (NCS) in human endometrium depends on the presence of progesteronal steroids. Materials & Methods Tissues of late proliferative endometrium ...Objective To determine whether formation of the nucleolar channel system (NCS) in human endometrium depends on the presence of progesteronal steroids. Materials & Methods Tissues of late proliferative endometrium were obtained from 5 normally cycling women of reproductive age. Half of each tissue was cultured in the DMEM medium containing diethylstilbesterol (25 μg/mL) plus medroxyprogesterone acetate (25 μg/mL) (E + P culture). As a control, the other half was cultured in the medium alone. After 100 h incubation, the tissues were assessed for the formation of NCS with transmission electron microscope.Results NCS was observed in the endometrial epithelium treated with E + P or the medium alone. Moreover, giant mitochondria and glycogen accumulation were both seen in epithelia derived from both types of cultures.Conclusion Progesterone would be not indispensable for the formation of NCS in human endometrium. Transition of proliferative endometrium to the secretory stage in vitro could occur even in the absence of both estrogen and progesterone.展开更多
This paper studies the problems of H-infinity performance optimization and controller design for continuous-time NCSs with both sensor-to-controller and controller-to-actuator communication constraints (limited commu...This paper studies the problems of H-infinity performance optimization and controller design for continuous-time NCSs with both sensor-to-controller and controller-to-actuator communication constraints (limited communication channels). By taking the derivative character of network-induced delay into full consideration and defining new Lyapunov functions, linear matrix inequalities (LMIs)-based H-infinity performance optimization and controller design are presented for NCSs with limited communication channels. If there do not exist any constraints on the communication channels, the proposed design methods are also applicable. The merit of the proposed methods lies in their Jess conservativeness, which is achieved by avoiding the utilization of bounding inequalities for cross products of vectors. The simulation results illustrate the merit and effectiveness of the proposed H-infinity controller design for NCSs with limited communication channels.展开更多
It is known that dynamic channel assignment(D CA ) strategy outperforms the fixed channel assignment(FCA) strategy in omni-direc tional antenna cellular systems. One of the most important methods used in DCA w as chan...It is known that dynamic channel assignment(D CA ) strategy outperforms the fixed channel assignment(FCA) strategy in omni-direc tional antenna cellular systems. One of the most important methods used in DCA w as channel borrowing. But with the emergence of cell sectorization and spatial d ivision multiple access(SDMA) which are used to increase the capacity of cel lular systems, the channel assignment faces a series of new problems. In this pa per, a dynamic channel allocation scheme based on sectored cellular systems is p roposed. By introducing intra-cell channel borrowing (borrowing channels from n eighboring sectors) and inter-cell channel borrowing (borrowing channels from n eighboring cells) methods, previous DCA strategies, including compact pattern ba sed channel borrowing(CPCB) and greedy based dynamic channel assignment(GDCA) schemes proposed by the author, are improved significantly. The computer simu lation shows that either intra-cell borrowing scheme or inter-cell borrowing s cheme is efficient enough to uniform and non-uniform traffic service distributi ons.展开更多
Due to the large number of users and the time-varying characteristics of wireless channels, it is very tough to inform the transmitter of full channel information in real multi-user MIMO broadcast systems. On the othe...Due to the large number of users and the time-varying characteristics of wireless channels, it is very tough to inform the transmitter of full channel information in real multi-user MIMO broadcast systems. On the other hand, the capacity of multi-user systems greatly depends on the knowledge of the channel at the transmitter while this is not always the case in single-user MIMO systems. In this paper, we investigate combined user selection and zero-forcing precoding schemes that use partial channel information, i.e., very low amount of channel information at the base station. We show that while greatly reducing the complexity and channel knowledge feedback load, the proposed schemes preserve the optimality of zero-forcing scheme in term of achievable ergodic sum capacity in limit of large number of active users.展开更多
A potential acceleration of a quantum open system is of fundamental interest in quantum computation, quantum communication, and quantum metrology. In this paper, we investigate the "quantum speed-up capacity" which ...A potential acceleration of a quantum open system is of fundamental interest in quantum computation, quantum communication, and quantum metrology. In this paper, we investigate the "quantum speed-up capacity" which reveals the potential ability of a quantum system to be accelerated. We explore the evolutions of the speed-up capacity in different quantum channels for two-qubit states. We find that although the dynamics of the capacity is varying in different kinds of channels, it is positive in most situations which are considered in the context except one case in the amplitude-damping channel. We give the reasons for the different features of the dynamics. Anyway, the speed-up capacity can be improved by the memory effect. We find two ways which may be used to control the capacity in an experiment: selecting an appropriate coefficient of an initial state or changing the memory degree of environments.展开更多
Based on more than 4000 km 2D seismic data and seismic stratigraphic analysis, we discussed the extent and formation mechanism of the Qiongdongnan deep sea channel. The Qiongdongnan deep sea channel is a large incised...Based on more than 4000 km 2D seismic data and seismic stratigraphic analysis, we discussed the extent and formation mechanism of the Qiongdongnan deep sea channel. The Qiongdongnan deep sea channel is a large incised channel which extends from the east boundary of the Yinggehai Basin, through the whole Qiongdongnan and the Xisha trough, and terminates in the western part of the northwest subbasin of South China Sea. It is more than 570 km long and 4–8 km wide. The chaotic (or continuous) middle (or high) amplitude, middle (or high) continuity seismic facies of the channel reflect the different lithological distribution of the channel. The channel formed as a complex result of global sea level drop during early Pliocene, large scale of sediment supply to the Yinggehai Basin, inversion event of the Red River strike-slip fault, and tilted direction of the Qiongdongnan Basin. The large scale of sediment supply from Red River caused the shelf break of the Yinggehai Basin to move torwards the S and SE direction and developed large scale of prograding wedge from the Miocene, and the inversion of the Red River strike-slip fault induced the sediment slump which formed the Qiongdongnan deep sea channel.展开更多
This paper presents a new method for the system identification of the channel roughness for the water diversion projects. According to the principle of hydraulics,the function relationship among channel roughness n, r...This paper presents a new method for the system identification of the channel roughness for the water diversion projects. According to the principle of hydraulics,the function relationship among channel roughness n, roughness height k s and hydraulic radius R is established,and then a linear model is deduced by means of the mathematical transformation to make use of the least square method for identification. Finally,based on the prototype observation data from the South-to-North Water Diversion Project and considering the influence of channel lengths,cross-section shapes and bottom slopes,etc,a universal formula is obtained for calculation of channel roughness by the system identification.展开更多
Background In real practice, two or more antihypertensive drugs are needed to achieve target blood pressure. We investigated the comparative beneficial actions of combination therapy of renin-angiotensin system inhibi...Background In real practice, two or more antihypertensive drugs are needed to achieve target blood pressure. We investigated the comparative beneficial actions of combination therapy of renin-angiotensin system inhibitors (RASI), with calcium channel blockers (CCB) over CCB monotherapy on the development of new-onset diabetes mellitus (NODM) in Korean patients during four-year follow-up periods. Methods A total of 3208 consecutive hypertensive patients without a history of diabetes mellitus who had been prescribed CCB were retrospectively enrolled from January 2004 to December 2012. These patients were divided into the two groups according to the additional use of RASI (the RASI group, n = 1221 and the no RASI group, n = 1987). Primary endpoint was NODM, defined as a fasting blood glucose ≥ 126 mg/dL or hemoglobin A1c ≥ 6.5%. Secondary endpoint was major adverse cardiac events (MACE) defined as total death, myocardial infarction (MI) and percutaneous coronary intervention (PCI). Results After propensity score-matched (PSM) analysis, two propensity- matched groups (939 pairs, n = 1878, C-statistic = 0.743) were generated. The incidences of NODM (HR = 1.009, 95% CI: 0.700–1.452, P = 0.962), MACE (HR = 0.877, 95% CI: 0.544–1.413, P = 0.589), total death, MI, PCI were similar between the two groups after PSM during four years. Conclusions The use of RASI in addition to CCB showed comparable incidences of NODM and MACE compared to CCB monotherapy in non-diabetic hypertensive Korean patients during four-year follow-up period. However, large-scaled randomized controlled clinical trials will be required for a more definitive conclusion.展开更多
Transmit diversity has been recently proposed to reduce the effects of fading channels in various wireless applications. Orthogonal transmit diersity (OTD) is one of the standardized techniques in 3G systems. In this ...Transmit diversity has been recently proposed to reduce the effects of fading channels in various wireless applications. Orthogonal transmit diersity (OTD) is one of the standardized techniques in 3G systems. In this paper, we apply orthogonal transmit diversity technique to multicarrier CDMA systems. Andlysis and simulation results show that performance benefits can be achieved compared with conventioal MC-CDMA systems in multipath fading channels.展开更多
In this paper the application of a cleaning system which was made up of a centrifugal fan with double channel and one sieve to 4LZ-3.5 combine was introduced. This cleaning system with double channel compared with the...In this paper the application of a cleaning system which was made up of a centrifugal fan with double channel and one sieve to 4LZ-3.5 combine was introduced. This cleaning system with double channel compared with the traditional air-sieve cleaning system of combines may omit one two sieves and simplify the transmission mechanism. It is also compared with the present cleaning system with double channel applied to some combines, such as the Commandor 112CS/ 228CS combines of Claas Corporation in Germany and the MAXIMIZERTMombincs of John Deerc company in U.S.A. It may omit one sieve and the preclcaner and simlify the transmission mechanism. The measuring results indicated that the cleaning ratio of wheat grain is 99.1% and the cleaning loss ratio of wheat is 0.17% when the feed rate is 4.01 kg/ s.展开更多
Offshore Nile Delta gas reservoirs are dominated by slope-channel systems of Plio-Pleistocene age. High-quality, three-dimensional seismic imaging has significantly helped in defining the geomorphology and architectur...Offshore Nile Delta gas reservoirs are dominated by slope-channel systems of Plio-Pleistocene age. High-quality, three-dimensional seismic imaging has significantly helped in defining the geomorphology and architectures of these channels. Integrating seismic, logs and core data from four wells resulted in understanding of different stages of channel development and reservoir quality. The studied reservoirs that are largely controlled by episodes of transgressive-regressive events resulted in deposition of fine grained sediment and shale. Sienna channel complex consists of unconfined channel system with clearly defined development stages. The stages include amalgamated or stacked channels followed by channel abandonment phases and local flooding events. The depositional pattern continued through the Late Pliocene-Pleistocene. SimSat-P1 and SimSat-P2 reservoirs are characterized by isolated sand bodies, most probably relics of fan depositional setting. The depositional scenario that is largely controlled by successive transgression and flooding events resulted in deposition of interbedded, sheet-like, fine grained sediment and shale.展开更多
文摘Contrary to the other multi-carrier modulation systems, the coherent optical orthogonal frequency division multiplexing communication system with an offset quadrature amplitude modulation (CO-OFDM-OQAM) possesses inherent imaginary interference (IMI). This has an important impact on the channel estimation process. Currently, a variety of frequency-domain channel estimation methods have been proposed. However, there are various problems that still exist. For instance, in order to reduce the influence of IMI, it is necessary to insert more guard intervals between the training sequence and the payload, leading to the occupation of excessive spectrum resources. In order to address this problem, this work designs a high spectral efficient frequency-domain channel estimation method for the polarization-division-multiplexing CO-OFDM-OQAM systems. First, the working principle of the proposed method is described in detail. Then, its spectral efficiency, power peak-to-average ratio, and channel estimation performance are studied based on simulations. The simulation results show that the proposed method improves the spectral efficiency without worsening the power peak-to-average ratio. The channel estimation capability of this method is verified in three scenarios of long-distance transmissions, including back-to-back, 100 km, and 200 km transmissions. .
基金supported by the National Key Scientific Instrument and Equipment Development Project(Grant No.2013YQ200607)China NSF Grants(Grant No.61631020)+2 种基金Aeronautical Science Foundation of China(Grant No.2017ZC52021)Fundamental Research Funds for the Central Universities(Grant No.NJ20160027)Open Foundation for Graduate Innovation of NUAA(Grant No.kfjj20160412 and kfjj20170405)
文摘In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel model, the cascaded propagation loss of relay link and the cascaded probability density function(PDF) of channel fading are derived. Moreover, the theoretical performance of the UAV-based relay system, i.e., the outage probability, bit error rate(BER), and channel capacity, is also analysed and derived. Simulation results show agreement with theoretical results for the hill, mountain, and sea scenarios, indicating the accuracy of both the simulations and derivations.
基金supported by Open Fund(PLC201203)of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology)National Science and Technology Major Project(2011ZX05030-005)Major Project of Education Department in Sichuan Province(13ZA0177)
文摘This paper studied an architecture model of turbidite channel systems based on the shallow- layer high resolution 3D seismic information in the deepwater area in the Niger Delta continental slope, West Africa as a prototype model. Different types of channel systems were identified and the corresponding architecture models were established. The controlling factors, evaluation criteria and spatial distribution of different channel systems were analyzed. This study shows that turbidite channel systems of West Africa could be classified into three types; confined, semi-confined and unconfined, according to the condition of canyon and the levees on both sides. Oil one hand, along the transport direction, channel system evolves from confined to unconfined. Within channel systems, channel complexes, including two types of incised and enveloped, are the most important reservoir bodies. On the other hand, there is a channel complex evolution from incised to enveloped vertically. The geological factors exert impacts of different levels on the architecture of the turbidite channels in different sedimentary systems or even within the same system.
基金Supported by National Natural Science Foundation of China (No. 60872123)Joint Fund of National Natural Science Foundation of China and Guangdong Provincial Natural Science Foundation (No. U0835001)Fundamental Research Funds for Central Universities (No. 2011ZM0033)
文摘To reduce channel noise,fading,and inter-user interference effectively in the chaotic communication systems with multi-user,a blind channel equalization algorithm based on dual unscented Kalman filter algorithm is proposed.Assuming that the coefficients of a multi-input multi-output (MIMO) channel can be described by an autoregressive model,two separate state-space representations are used for the signals and coefficients.Then two unscented Kalman filters are used to estimate chaotic signals and channel coefficients simultaneously.The simulation results indicate that the algorithm can effectively track the coefficients of the multi-path fading channel in chaotic MIMO communication systems at a fast convergence speed.
文摘Human normal endometrium was examined in ultrathin sections.Nucleolar channel system(NCS) appeared in the endometrial epithelial cells during the early and mid secretory phase of menstrual cycle.The NCS was a hollow ball like structure of different sizes and was composed of 2 to 5 rows of tubules embedded in an amporphous matrix.On its surface there were numerous electron dense particles resembling ribosomes,It was usually located within or associated with the nucleolus,SOmetimes,it was close to the nuclear envelope or protruding out from the nucleus .On occasion,NCS with simplified structure was found in the perinuclear cytoplasm.Concepts concerning the genesis,involution and function(s) of the NCS were disussed.
文摘This paper addresses the issues of channel estimation in a Multiple-Input/Multiple-Output (MIMO) system. Markov Chain Monte Carlo (MCMC) method is employed to jointly estimate the Channel State Information (CSI) and the transmitted signals. The deduced algorithms can work well under circumstances of low Signal-to-Noise Ratio (SNR). Simulation results are presented to demonstrate their effectiveness.
基金by the National Natural Science Foundation of China (No.60496311).
文摘In this paper, the effect of channel estimation errors upon the Zero Forcing (ZF) precoding Multiple Input Multiple Output Broadcast (MIMO BC) systems was studied. Based on the two kinds of Gaussian estimation error models, the performance analysis is conducted under different power allocation strategies. Analysis and simulation show that if the covariance of channel estimation errors is independent of the received Signal to Noise Ratio (SNR), imperfect channel knowledge deteriorates the sum capacity and the Bit Error Rate (BER) performance severely. However, under the situation of orthogonal training and the Minimum Mean Square Error (MMSE) channel estimation, the sum ca- pacity and BER performance are consistent with those of the perfect Channel State Information (CSI) with only a performance degradation.
文摘A data acquisition system (DAS) to implement high-speed, real-time and multi-channel data acquisition and store is presented. The control of the system is implemented by the combination of complex programable logic device (CPLD) and digital signal processing (DSP), the bulk buffer of the system is implemented by the combination of CPLD, DSP, and synchronous dynamic random access memory (SDRAM), and the data transfer is implemented by the combination of DSP, first in first out (FIFO), universal serial bus (USB) and USB hub. The system could not only work independently in single-channel mode, but also implement high-speed real-time multi-channel data acquisition system (MCDAS) by the combination of multiple single-channels. The sampling rate and data storage capacity of each channel could reach up to 100 million sampiing per second and 256 MB respectively.
基金This study was supported by the National Science Fund of P.R.China (No.39970765)
文摘Objective To determine whether formation of the nucleolar channel system (NCS) in human endometrium depends on the presence of progesteronal steroids. Materials & Methods Tissues of late proliferative endometrium were obtained from 5 normally cycling women of reproductive age. Half of each tissue was cultured in the DMEM medium containing diethylstilbesterol (25 μg/mL) plus medroxyprogesterone acetate (25 μg/mL) (E + P culture). As a control, the other half was cultured in the medium alone. After 100 h incubation, the tissues were assessed for the formation of NCS with transmission electron microscope.Results NCS was observed in the endometrial epithelium treated with E + P or the medium alone. Moreover, giant mitochondria and glycogen accumulation were both seen in epithelia derived from both types of cultures.Conclusion Progesterone would be not indispensable for the formation of NCS in human endometrium. Transition of proliferative endometrium to the secretory stage in vitro could occur even in the absence of both estrogen and progesterone.
基金supported by the Funds for Creative Research Groups of China(No.60821063)the State Key Program of National Natural Science of China(No.60534010)+3 种基金the National 973 Program of China(No.2009CB320604)the Funds of National Science of China(No.60674021,60804024)the 111 Project(No.B08015)the Funds of PhD program of MOE,China(No.20060145019)
文摘This paper studies the problems of H-infinity performance optimization and controller design for continuous-time NCSs with both sensor-to-controller and controller-to-actuator communication constraints (limited communication channels). By taking the derivative character of network-induced delay into full consideration and defining new Lyapunov functions, linear matrix inequalities (LMIs)-based H-infinity performance optimization and controller design are presented for NCSs with limited communication channels. If there do not exist any constraints on the communication channels, the proposed design methods are also applicable. The merit of the proposed methods lies in their Jess conservativeness, which is achieved by avoiding the utilization of bounding inequalities for cross products of vectors. The simulation results illustrate the merit and effectiveness of the proposed H-infinity controller design for NCSs with limited communication channels.
文摘It is known that dynamic channel assignment(D CA ) strategy outperforms the fixed channel assignment(FCA) strategy in omni-direc tional antenna cellular systems. One of the most important methods used in DCA w as channel borrowing. But with the emergence of cell sectorization and spatial d ivision multiple access(SDMA) which are used to increase the capacity of cel lular systems, the channel assignment faces a series of new problems. In this pa per, a dynamic channel allocation scheme based on sectored cellular systems is p roposed. By introducing intra-cell channel borrowing (borrowing channels from n eighboring sectors) and inter-cell channel borrowing (borrowing channels from n eighboring cells) methods, previous DCA strategies, including compact pattern ba sed channel borrowing(CPCB) and greedy based dynamic channel assignment(GDCA) schemes proposed by the author, are improved significantly. The computer simu lation shows that either intra-cell borrowing scheme or inter-cell borrowing s cheme is efficient enough to uniform and non-uniform traffic service distributi ons.
文摘Due to the large number of users and the time-varying characteristics of wireless channels, it is very tough to inform the transmitter of full channel information in real multi-user MIMO broadcast systems. On the other hand, the capacity of multi-user systems greatly depends on the knowledge of the channel at the transmitter while this is not always the case in single-user MIMO systems. In this paper, we investigate combined user selection and zero-forcing precoding schemes that use partial channel information, i.e., very low amount of channel information at the base station. We show that while greatly reducing the complexity and channel knowledge feedback load, the proposed schemes preserve the optimality of zero-forcing scheme in term of achievable ergodic sum capacity in limit of large number of active users.
基金supported by the EU FP7 Marie–Curie Career Integration Fund(Grant No.631883)the Royal Society Research Fund(Grant No.RG150036)the Fundamental Research Fund for the Central Universities,China(Grant No.2018IB010)
文摘A potential acceleration of a quantum open system is of fundamental interest in quantum computation, quantum communication, and quantum metrology. In this paper, we investigate the "quantum speed-up capacity" which reveals the potential ability of a quantum system to be accelerated. We explore the evolutions of the speed-up capacity in different quantum channels for two-qubit states. We find that although the dynamics of the capacity is varying in different kinds of channels, it is positive in most situations which are considered in the context except one case in the amplitude-damping channel. We give the reasons for the different features of the dynamics. Anyway, the speed-up capacity can be improved by the memory effect. We find two ways which may be used to control the capacity in an experiment: selecting an appropriate coefficient of an initial state or changing the memory degree of environments.
基金This work is supported by the joint foundation of National Science Foundation of China (NSFC) and Guangdong Province U0635003, and also supported by the National Science Foundation of China ( NSFC), Grant 60772132.
基金Supported by the National High Technology Research and Development Program of China (863 Program, 2006AA09Z349)the National Basic Research Program of China (2007CB411703)
文摘Based on more than 4000 km 2D seismic data and seismic stratigraphic analysis, we discussed the extent and formation mechanism of the Qiongdongnan deep sea channel. The Qiongdongnan deep sea channel is a large incised channel which extends from the east boundary of the Yinggehai Basin, through the whole Qiongdongnan and the Xisha trough, and terminates in the western part of the northwest subbasin of South China Sea. It is more than 570 km long and 4–8 km wide. The chaotic (or continuous) middle (or high) amplitude, middle (or high) continuity seismic facies of the channel reflect the different lithological distribution of the channel. The channel formed as a complex result of global sea level drop during early Pliocene, large scale of sediment supply to the Yinggehai Basin, inversion event of the Red River strike-slip fault, and tilted direction of the Qiongdongnan Basin. The large scale of sediment supply from Red River caused the shelf break of the Yinggehai Basin to move torwards the S and SE direction and developed large scale of prograding wedge from the Miocene, and the inversion of the Red River strike-slip fault induced the sediment slump which formed the Qiongdongnan deep sea channel.
基金Expert Comittee Key Special Found Project of State Council South-to-North Water Diversion Construction Committee(No.JGZXSY2009-11)
文摘This paper presents a new method for the system identification of the channel roughness for the water diversion projects. According to the principle of hydraulics,the function relationship among channel roughness n, roughness height k s and hydraulic radius R is established,and then a linear model is deduced by means of the mathematical transformation to make use of the least square method for identification. Finally,based on the prototype observation data from the South-to-North Water Diversion Project and considering the influence of channel lengths,cross-section shapes and bottom slopes,etc,a universal formula is obtained for calculation of channel roughness by the system identification.
文摘Background In real practice, two or more antihypertensive drugs are needed to achieve target blood pressure. We investigated the comparative beneficial actions of combination therapy of renin-angiotensin system inhibitors (RASI), with calcium channel blockers (CCB) over CCB monotherapy on the development of new-onset diabetes mellitus (NODM) in Korean patients during four-year follow-up periods. Methods A total of 3208 consecutive hypertensive patients without a history of diabetes mellitus who had been prescribed CCB were retrospectively enrolled from January 2004 to December 2012. These patients were divided into the two groups according to the additional use of RASI (the RASI group, n = 1221 and the no RASI group, n = 1987). Primary endpoint was NODM, defined as a fasting blood glucose ≥ 126 mg/dL or hemoglobin A1c ≥ 6.5%. Secondary endpoint was major adverse cardiac events (MACE) defined as total death, myocardial infarction (MI) and percutaneous coronary intervention (PCI). Results After propensity score-matched (PSM) analysis, two propensity- matched groups (939 pairs, n = 1878, C-statistic = 0.743) were generated. The incidences of NODM (HR = 1.009, 95% CI: 0.700–1.452, P = 0.962), MACE (HR = 0.877, 95% CI: 0.544–1.413, P = 0.589), total death, MI, PCI were similar between the two groups after PSM during four years. Conclusions The use of RASI in addition to CCB showed comparable incidences of NODM and MACE compared to CCB monotherapy in non-diabetic hypertensive Korean patients during four-year follow-up period. However, large-scaled randomized controlled clinical trials will be required for a more definitive conclusion.
文摘Transmit diversity has been recently proposed to reduce the effects of fading channels in various wireless applications. Orthogonal transmit diersity (OTD) is one of the standardized techniques in 3G systems. In this paper, we apply orthogonal transmit diversity technique to multicarrier CDMA systems. Andlysis and simulation results show that performance benefits can be achieved compared with conventioal MC-CDMA systems in multipath fading channels.
文摘In this paper the application of a cleaning system which was made up of a centrifugal fan with double channel and one sieve to 4LZ-3.5 combine was introduced. This cleaning system with double channel compared with the traditional air-sieve cleaning system of combines may omit one two sieves and simplify the transmission mechanism. It is also compared with the present cleaning system with double channel applied to some combines, such as the Commandor 112CS/ 228CS combines of Claas Corporation in Germany and the MAXIMIZERTMombincs of John Deerc company in U.S.A. It may omit one sieve and the preclcaner and simlify the transmission mechanism. The measuring results indicated that the cleaning ratio of wheat grain is 99.1% and the cleaning loss ratio of wheat is 0.17% when the feed rate is 4.01 kg/ s.
文摘Offshore Nile Delta gas reservoirs are dominated by slope-channel systems of Plio-Pleistocene age. High-quality, three-dimensional seismic imaging has significantly helped in defining the geomorphology and architectures of these channels. Integrating seismic, logs and core data from four wells resulted in understanding of different stages of channel development and reservoir quality. The studied reservoirs that are largely controlled by episodes of transgressive-regressive events resulted in deposition of fine grained sediment and shale. Sienna channel complex consists of unconfined channel system with clearly defined development stages. The stages include amalgamated or stacked channels followed by channel abandonment phases and local flooding events. The depositional pattern continued through the Late Pliocene-Pleistocene. SimSat-P1 and SimSat-P2 reservoirs are characterized by isolated sand bodies, most probably relics of fan depositional setting. The depositional scenario that is largely controlled by successive transgression and flooding events resulted in deposition of interbedded, sheet-like, fine grained sediment and shale.