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Search Results: 1 - 10 of 61411 matches for " XiaoMin Yu "
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Two-dimensional Noncommutative atom Gas with Anandan interaction
Xiaomin Yu,Kang Li
Physics , 2011, DOI: 10.1103/PhysRevA.84.033617
Abstract: Landau like quantization of the Anandan system in a special electromagnetic field is studied. Unlike the cases of the AC system and the HMW system, the torques of the system on the magnetic dipole and the electric dipole don't vanish. By constructing Heisenberg algebra, the Landau analog levels and eigenstates on commutative space, NC space and NC phase space are obtained respectively. By using the coherent state method, some statistical properties of such free atom gas are studied and the expressions of some thermodynamic quantities related to revolution direction are obtained. Two particular cases of temperature are discussed and the more simple expressions of the free energy on the three spaces are obtained. We give the relation between the value of $\sigma$ and revolution direction clearly, and find Landau like levels of the Anandan system are invariant and the levels between the AC system and the HMW system are interchanged each other under Maxwell dual transformations on the three spaces. The two sets of eigenstates labelled by $\sigma$ can be related by a supersymmetry transformation on commutative space, but the phenomenon don't occur on NC situation. We emphasize that some results relevant to Anandan interaction are suitable for the cases of AC interaction and HMW interaction under special conditions.
Performance of Cross-Layer Design with Antenna Selection and Imperfect Feedback Information in MIMO Systems
Xiaoyu Dang,Xiangbin Yu,Xiaomin Chen
International Journal of Antennas and Propagation , 2012, DOI: 10.1155/2012/328457
Abstract: By combining adaptive modulation and automatic repeat request, a cross-layer design (CLD) scheme for MIMO system with antenna selection (AS) and imperfect feedback is presented, and the corresponding performance is studied. Subject to a target packet loss rate and fixed power constraint, the variable switching thresholds of fading gain are derived. According to these results, and using mathematical manipulation, the average spectrum efficiency (SE) and packet error rate (PER) of the system are further derived. As a result, closed-form expressions of the average SE and PER are obtained, respectively. These expressions include the expressions under perfect channel state information as special cases and provide good performance evaluation for the system. Numerical results show that the proposed CLD scheme with antenna selection has higher SE than the existing CLD scheme with space-time block coding, and the CLD scheme with variable switching thresholds outperforms that with conventional-fixed switching thresholds. 1. Introduction With the fast development of modern communication techniques, the demand for high data rate service is growing increasingly in the limited radio spectrum. For this reason, the future wireless communication systems will require spectrally efficient techniques to increase the system capacity. Cross-layer design (CLD), as a good work to improve the spectral efficiency (SE) and system throughput of future wireless systems while meeting the prescribed quality of service (QoS) requirements, has received much attention recently [1–3]. Especially, CLD combining adaptive modulation (AM) and automatic repeat request (ARQ) which is widely accepted as an efficient means to improve the overall performance of transmission in fading channels has been introduced in the improved 3G scheme, such as high-speed downlink packet access (HSDPA) [4–8]. Antenna selection (AS), which is a one promising approach to achieve the goal of providing performance benefits while significantly decreasing the hardware complexity and cost, has received considerable studies [9–11]. It can provide a good tradeoff between the performance, cost, and complexity and can be realized at both ends. Therefore, effective combination of cross-layer design and antenna selection techniques will receive much attention for practical purpose. The transmit antenna selection scheme with maximal ratio combining (MRC) is an effective diversity scheme [9, 10]. Based on this antenna selection scheme, the performance analysis of discrete-rate adaptive M-ray quadrature amplitude modulation
SVD-Aided Beamforming and Power Allocation Algorithm for Multiuser Turbo-BLAST System Uplink with Imperfect CSI
Xiaomin Chen,Xiangbin Yu,Dazhuan Xu
International Journal of Antennas and Propagation , 2012, DOI: 10.1155/2012/357381
Abstract: The SVD-aided joint transmitter and receiver design for the uplink of CDMA-based synchronous multiuser Turbo-BLAST systems is proposed in the presence of channel state information (CSI) imperfection. At the transmitter, the beamforming and power allocation schemes are developed to maximize the capacity of the desired user. At the receiver, a suboptimal decorrelating scheme is first proposed to mitigate the multiuser interference (MUI) and decouple the detection of different users with imperfect CSI, and then the iterative detecting algorithm that takes the channel estimation error into account is designed to cancel the coantenna interference (CAI) and enhance the bit error rate (BER) results further. Simulation results show that the proposed uplink CDMA-based multiuser Turbo-BLAST model is effective, the detection from every user is completely independent to each other after decorrelating, and the system performance can be enhanced by the proposed beamforming and power allocation schemes. Furthermore, BER performance can be enhanced by the modified iterative detection. The effect of CSI imperfection is evaluated, which is proved to be a useful tool to assess the system performance with imperfect CSI.
SVD-Aided Power Allocation and Iterative Detection Scheme for Turbo-BLAST System with Imperfect Channel State Information
Xiaomin Chen,Xiangbin Yu,Dazhuan Xu
International Journal of Antennas and Propagation , 2011, DOI: 10.1155/2011/505606
Abstract: A new technique that combines adaptive power allocation and iterative detection based on singular value decomposition (SVD) is introduced for the modified Turbo-BLAST system with imperfect channel state information (I-CSI). At the transmitter, in order to maximize the capacity performance, the MIMO channel is decomposed into several parallel eigen subchannels by SVD, and then proper power based on the water-filling principle is allocated to every subchannel subject to the total transmit power constraint. At the receiver, the modified MMSE detector taking the CSI imperfection into account is used to remove the coantenna interference, and then the turbo idea is employed for iterative detection to lower the system BER. As a result, the BER performance is effectively enhanced. Numerical results show that the introduced SVD-aided adaptive power allocation method is valid to improve not only the capacity but also the BER performance in the presence of channel state information imperfection, while the iterative detector can further lower the BER results. 1. Introduction Multiple-input multiple-output (MIMO) systems can provide a significant capacity increment over the conventional one through appropriate space-time processing [1, 2]. Bell labs layered space-time (BLAST) structure is one of the promising architectures thanks to the advantages of low detection complexity and high data rates [3]. The new system which combined BLAST structure with turbo idea is called Turbo-BLAST that can offer a reliable and practical solution to high data-rate transmission for wireless communications [4]. One of the attractive features of MIMO system is a multiplexing gain and consequently a higher capacity performance over single-input single-output system. When channel state information (CSI) is perfect, the water-filling power allocation strategy [5–7] is optimized to improve the capacity performance for MIMO systems. Practically, CSI at the receiver is subject to the error due to nonreal time data processing, and so forth [8]. For the modified Turbo-BLAST system, the task of designing the effective link adaptive technique becomes more challenging in the presence of CSI imperfection. Recently, various contributions have also considered the MIMO transceiver design problem for systems with either partial or imperfect CSI at the transmitter [9–12]. In these references, the effect of I-CSI on the capacity performance of MIMO system is investigated in [9, 10]. Based on the perfect and imperfect CSI, the performance of adaptive modulation schemes in MIMO systems is analyzed in
Adaptive Transmit Antenna Selection and Power Allocation Scheme for Turbo-Blast System with Imperfect Channel State Information
Xiaomin Chen;Dazhuan Xu;Xiangbin Yu
PIER C , 2009, DOI: 10.2528/PIERC09071503
Abstract: In this paper, a new technique that combines adaptive transmit antenna selection, transmit power allocation and iterative detection is introduced for the modified Turbo-BLAST system. At the transmitter, in order to minimize the BER performance of the overall system, an adaptive transmit antenna selection scheme is proposed to select the appropriate antenna subset for the actual transmission, and the proper power is allocated for the selected antennas subject to the total transmit power constraint. At the receiver the modified MMSE detector taking the imperfect CSI into account is used to remove the co-antenna interference. Finally the turbo principle is employed for iterative detection to further lower the BER results. Simulation results show that the introduced adaptive transmit antenna selection and power allocation algorithm can significantly improve the BER performance, and the iterative detection technique can further enhance the performance.
Application Study on Multi-Vary Analysis  [PDF]
Xiaomin Xu
Modern Mechanical Engineering (MME) , 2013, DOI: 10.4236/mme.2013.31005

In this article, we studied the bearings made by one company in Shanghai. Through statistical process controlling the quality characteristic of bearings’ diameters and multi-vary analysis is applied to find the key variation factors which have an influence on the quality characteristic of the bearings, the quality level of the bearings of this company is improved.

Novel Understanding of Electron States Architecture and Its Dimensionality in Semiconductors  [PDF]
Xiaomin Ren
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.32B075

Some important insights into the electron-states-architecture (ESA) and its dimensionality (from 3 to 0) in a semiconductor (or generally crystalline) material are obtained. The self-consistency of the set of density of states (DOS) expressions with different dimensionalities is remediated through the clarification and rearrangement of the wave-function boundary conditions for working out the eigenvalues in the wave vector space. The actually too roughly observed and theoretically unpredicted critical points for the dimensionality transitions referring to the integer ones are revealed upon an unusual assumption of the intrinsic energy-level dispersion (ELD). The ELD based quantitative physical model had been established on an immediate instinct at the very beginning and has been properly modified afterwards. The uncertainty regarding the relationship between the de Broglie wavelength of electrons and the dimensionality transitions, seeming somewhat mysterious before, is consequentially eliminated. The effect of the material dimensions on the ELD width is also predicted and has been included in the model. The continuous evolution of the ESA dimensionality is convincingly and comprehensively interpreted and thus the area of the fractional ESA dimensionalities is opened. Another new assumption of the spatial extension shrinkage (SES) closely related to the ELD has also been made and thus the understanding of the behavior of an electron or, in a general sense, a particle has become more comprehensive. This work would manifest itself a new basis for further development of nanoheterostructures (or low dimensional heterostructures including the quantum wells, quantum wires, quantum dots and especially the hetero-dimensional structures). Expected

When “Parents Privilege Competition” Will Not Be an Exclusive Resource?  [PDF]
Xiaomin Guo
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.64004
We describe a common social phenomenon in this article. It is that when children grow up, in addition to their talents and efforts in comparison with their peers, the parental background between children is also an important stake in their competition. Parents’ social status and superior power will result in more social resources and opportunities for children. We call this phenomenon “parents privilege competition”. The root cause of this phenomenon is the serious hardening of the stratum and the poor social mobility in vertical society, which makes it difficult for children to have an equal competitive environment. After analyzing the phenomenon, this article discusses the causes of this phenomenon and the solutions.
Multi-amplitude Differential Space-time Block Coding Scheme for Square/Non-Square Code Matrix in MIMO Systems
Xiangbin Yu,Xiaomin Chen,Yuyu Xin,Qiuming Zhu
Journal of Networks , 2012, DOI: 10.4304/jnw.7.5.884-892
Abstract: Differential space-time coding (DSTC) technique has become a good choice when channel estimations are difficult to obtain in multiple antennas system. On the basis of analyzing the existing DSTC schemes, by introducing multi-level quadrature amplitude modulation (MQAM) and matrix transform method, we develop a multi-amplitude differential space-time block coding (STBC) scheme for square or non-square code matrix in MIMO systems, and give the derivation of calculation formulae of the coding advantage in detail. The developed scheme can effectively avoid the performance loss of conventional DSTC schemes based on PSK modulation (i.e. single amplitude DSTC) in high spectrum efficiency. It can be applied to non-square code matrix case, and thus overcomes the shortcoming that existing DSTC schemes are only suitable for square code matrix. Compared with single amplitude DSTC schemes, our scheme has higher spectrum efficiency by carrying information not only on phases but also on amplitudes. Moreover, our scheme has linear decoding complexity, higher coding advantage, and higher code rate for more than two antennas. The simulations results show that the proposed scheme can provide lower BER than the existing single amplitude differential STBC schemes for both square and non-square code matrices
Latency Estimation-Based Data Delivery Scheme for Vehicular Ad Hoc Networks
Haigang Gong,Lingfei Yu,Ke Liu,Fulong Xu,Xiaomin Wang
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/527097
Abstract: Data delivery is the most compelling issue for the applications in vehicular ad hoc networks. The characteristics of VAENTs such as highly dynamic topology and the road-constrained mobility pose great challenges for data delivery in vehicular ad hoc networks. In this paper, a latency estimation-based data delivery (LED) scheme is presented. According to the current location and the moving direction of the vehicles, LED calculates the expected delivery latency (EDL) of each vehicle and chooses the vehicle with the shortest EDL as the next hop to forward data. Simulation results show that LED performs better than VADD. 1. Introduction Vehicular ad hoc networks have been envisioned to be promising in road safety and many other commercial applications, such as the intelligent transportation system (ITS), one of the most important applications of VANET, which have been deployed in USA, Europe, and Asia. For example, with the ITS, an emergency warning can help drivers behind a crashed vehicle (or incident) to avoid multicar collisions [1]. Besides, a vehicular network can be used to alert drivers to potential traffic jams, providing more convenience and efficiency. Vehicular ad hoc networks have some characteristics as follows: (1) the topology of VANETs changes rapidly due to the high mobility of the vehicles. Different from the traditional node-to-node pattern of routing which is based on the mobile node topology in mobile ad hoc networks (MANETs) [2–6], VANETs usually cannot establish a stable end-to-end path to transmit data packets due to the intermittent connectivity [7–9]. (2) The mobility of vehicle nodes in VANETs is constrained by predefined roads. Due to the buildings and other obstacles, the data delivery based on the V2V communications over VANETs is also constrained by the roads. Efficient data delivery based on infrastructure-less V2V communications is the most compelling issue for the mentioned applications in VANETs. However, the characteristics of VAENTs such as highly dynamic topology and the road-constrained mobility pose great challenges for data delivery in vehicular ad hoc networks. Some researches have been proposed to resolve data forwarding for vehicular networks. GPSR [4] is a geographical forwarding approach which always chooses the next hop closer to the destination. It is a classic and very efficient data delivery scheme in ad hoc networks, but it may not be suitable for sparsely connected vehicular networks and it cannot select a path with lower latency. Zhao and Cao present VADD [7], which utilizes the predictable mobility in
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