Hybrid precoding can reduce the number of required radio frequency(RF)chains in millimeter-Wave(mmWave) massive MIMO systems. However, existing hybrid precoding based on singular value decomposition(SVD) requires the ...Hybrid precoding can reduce the number of required radio frequency(RF)chains in millimeter-Wave(mmWave) massive MIMO systems. However, existing hybrid precoding based on singular value decomposition(SVD) requires the complicated bit allocation to match the different signal-to-noise-ratios(SNRs) of different sub-channels. In this paper,we propose a geometric mean decomposition(GMD)-based hybrid precoding to avoid the complicated bit allocation. Specifically,we seek a pair of analog and digital precoders sufficiently close to the unconstrained fully digital GMD precoder. To achieve this, we fix the analog precoder to design the digital precoder, and vice versa. The analog precoder is designed based on the orthogonal matching pursuit(OMP) algorithm, while GMD is used to obtain the digital precoder. Simulations show that the proposed GMD-based hybrid precoding achieves better performance than the conventional SVD-based hybrid precoding with only a slight increase in complexity.展开更多
Earthquake engineers have made a lot of efforts to derive a comprehensive set of closed form expressions for performance evaluation of frames, which are already presented in guidelines such as SAC/FEMA. These analytic...Earthquake engineers have made a lot of efforts to derive a comprehensive set of closed form expressions for performance evaluation of frames, which are already presented in guidelines such as SAC/FEMA. These analytical expressions have been developed to estimate the annual probability of exceeding a limit state. In the process of such seismic assessments, some essential assumptions are adopted to simplify the process. One of these fundamental assumptions declares that drift demand at any seismic intensity level follows a lognormal distribution around its median. To investigate the validity of this assumption, this paper describes a case study of the types of errors that could be produced by using the sample median as the central tendency. Based on the Maximum Likelihood Estimation method as well as other statistical evidence, this paper proposes the use of the sample geometric mean instead of the sample median for the central tendency. Further, the results of seismic reliability evaluations of 4 sample frames are compared based on utilizing both the geometric mean and the sample median. In this process, both first and second order power law fits of the hazard curve are implemented to compare the effects of hazard estimation and the selection of the central tendency on the final results. It is observed in the application example that the sample geometric mean could lead to more accurate results.展开更多
In the present paper, we answer the question: for 0a what are the greatest value p(a) and the least value q(a) such that the double inequality Jp(a,b)aA(a,b)+ (1-a)G(a,b)Jq(a,b) holds for all a,b>0 with a is not eq...In the present paper, we answer the question: for 0a what are the greatest value p(a) and the least value q(a) such that the double inequality Jp(a,b)aA(a,b)+ (1-a)G(a,b)Jq(a,b) holds for all a,b>0 with a is not equal to?b ?展开更多
Today environmental assessment is considered and used as the basis and foundation of any kind of human activity. This is the science which gives human the consciousness about abilities and disabilities of his surround...Today environmental assessment is considered and used as the basis and foundation of any kind of human activity. This is the science which gives human the consciousness about abilities and disabilities of his surroundings. This study tried to assess and provide the potential survey of lands in Khuzestan province for agricultural activities by taking into account the climatic elements and displaying different elements in different seasons. To achieve this goal, first produced data were analyzed in GIS software and then the data was tested by professors and experts of department of soil science and was weighted using the Buckley geometric mean model. Finally, the obtained weights were applied in the software and the obtained results are as follow: except some east parts of Khuzestan province which have proper climate for agricultural activities, other regions are not in good conditions and it is necessary to use cultivation with low water requirements and high resistance to heat and sunlight in these areas.展开更多
We consider maps on positive definite cones of von Neumann algebras preserving unitarily invariant norms of the spectral geometric means. The main results concern Jordan *-isomorphisms between <em>C</em>*-...We consider maps on positive definite cones of von Neumann algebras preserving unitarily invariant norms of the spectral geometric means. The main results concern Jordan *-isomorphisms between <em>C</em>*-algebras, and show that they are characterized by the preservation of unitarily invariant norms of those operations.展开更多
In this paper, we consider the norms related to spectral geometric means and geometric means. When A and B are positive and invertible, we have ||A<sup>-1</sup>#B|| ≤ ||A<sup>-1</sup>σ<sub...In this paper, we consider the norms related to spectral geometric means and geometric means. When A and B are positive and invertible, we have ||A<sup>-1</sup>#B|| ≤ ||A<sup>-1</sup>σ<sub>s</sub>B||. Let H be a Hilbert space and B(H) be the set of all bounded linear operators on H. Let A ∈ B(H). If ||A#X|| = ||Aσ<sub>s</sub>X||, ?X ∈ B(H)<sup>++</sup>, then A is a scalar. When is a C*-algebra and for any , we have that ||logA#B|| = ||logAσ<sub>s</sub>B||, then is commutative.展开更多
现有的GMD-TH(Geometric Mean Decomposition-Tomlison Harashima)预编码方案在发射端未对获得MIMO(Multiple-Input-Multiple-Output)信道增益矩阵优化,因而其误码率和分集增益无法获得令人满意的效果。为此,在原有MIMO系统GMD-TH预编...现有的GMD-TH(Geometric Mean Decomposition-Tomlison Harashima)预编码方案在发射端未对获得MIMO(Multiple-Input-Multiple-Output)信道增益矩阵优化,因而其误码率和分集增益无法获得令人满意的效果。为此,在原有MIMO系统GMD-TH预编码的基础上,提出一种基于格规约辅助的GMD-TH预编码方案。该方案采用基于格规约的算法对信道矩阵进行优化,经过优化的信道矩阵其列向量之间具有更好的正交性并且向量的长度更短,并且采用优化的信道矩阵提高了GMD-TH预编码MIMO系统的分集增益。仿真结果表明:相比于传统的线性预编码方案,该预编码方案有效地提高了MIMO分集增益,相同误码率下,信噪比降低3 dB以上,具有实用价值。展开更多
基金supported by the National Natural Science Foundation of China for Outstanding Young Scholars (Grant No. 61722109)the National Natural Science Foundation of China (Grant No. 61571270)the Royal Academy of Engineering through the UK–China Industry Academia Partnership Programme Scheme (Grant No. UK-CIAPP\49)
文摘Hybrid precoding can reduce the number of required radio frequency(RF)chains in millimeter-Wave(mmWave) massive MIMO systems. However, existing hybrid precoding based on singular value decomposition(SVD) requires the complicated bit allocation to match the different signal-to-noise-ratios(SNRs) of different sub-channels. In this paper,we propose a geometric mean decomposition(GMD)-based hybrid precoding to avoid the complicated bit allocation. Specifically,we seek a pair of analog and digital precoders sufficiently close to the unconstrained fully digital GMD precoder. To achieve this, we fix the analog precoder to design the digital precoder, and vice versa. The analog precoder is designed based on the orthogonal matching pursuit(OMP) algorithm, while GMD is used to obtain the digital precoder. Simulations show that the proposed GMD-based hybrid precoding achieves better performance than the conventional SVD-based hybrid precoding with only a slight increase in complexity.
文摘Earthquake engineers have made a lot of efforts to derive a comprehensive set of closed form expressions for performance evaluation of frames, which are already presented in guidelines such as SAC/FEMA. These analytical expressions have been developed to estimate the annual probability of exceeding a limit state. In the process of such seismic assessments, some essential assumptions are adopted to simplify the process. One of these fundamental assumptions declares that drift demand at any seismic intensity level follows a lognormal distribution around its median. To investigate the validity of this assumption, this paper describes a case study of the types of errors that could be produced by using the sample median as the central tendency. Based on the Maximum Likelihood Estimation method as well as other statistical evidence, this paper proposes the use of the sample geometric mean instead of the sample median for the central tendency. Further, the results of seismic reliability evaluations of 4 sample frames are compared based on utilizing both the geometric mean and the sample median. In this process, both first and second order power law fits of the hazard curve are implemented to compare the effects of hazard estimation and the selection of the central tendency on the final results. It is observed in the application example that the sample geometric mean could lead to more accurate results.
文摘In the present paper, we answer the question: for 0a what are the greatest value p(a) and the least value q(a) such that the double inequality Jp(a,b)aA(a,b)+ (1-a)G(a,b)Jq(a,b) holds for all a,b>0 with a is not equal to?b ?
文摘Today environmental assessment is considered and used as the basis and foundation of any kind of human activity. This is the science which gives human the consciousness about abilities and disabilities of his surroundings. This study tried to assess and provide the potential survey of lands in Khuzestan province for agricultural activities by taking into account the climatic elements and displaying different elements in different seasons. To achieve this goal, first produced data were analyzed in GIS software and then the data was tested by professors and experts of department of soil science and was weighted using the Buckley geometric mean model. Finally, the obtained weights were applied in the software and the obtained results are as follow: except some east parts of Khuzestan province which have proper climate for agricultural activities, other regions are not in good conditions and it is necessary to use cultivation with low water requirements and high resistance to heat and sunlight in these areas.
文摘We consider maps on positive definite cones of von Neumann algebras preserving unitarily invariant norms of the spectral geometric means. The main results concern Jordan *-isomorphisms between <em>C</em>*-algebras, and show that they are characterized by the preservation of unitarily invariant norms of those operations.
文摘In this paper, we consider the norms related to spectral geometric means and geometric means. When A and B are positive and invertible, we have ||A<sup>-1</sup>#B|| ≤ ||A<sup>-1</sup>σ<sub>s</sub>B||. Let H be a Hilbert space and B(H) be the set of all bounded linear operators on H. Let A ∈ B(H). If ||A#X|| = ||Aσ<sub>s</sub>X||, ?X ∈ B(H)<sup>++</sup>, then A is a scalar. When is a C*-algebra and for any , we have that ||logA#B|| = ||logAσ<sub>s</sub>B||, then is commutative.
文摘现有的GMD-TH(Geometric Mean Decomposition-Tomlison Harashima)预编码方案在发射端未对获得MIMO(Multiple-Input-Multiple-Output)信道增益矩阵优化,因而其误码率和分集增益无法获得令人满意的效果。为此,在原有MIMO系统GMD-TH预编码的基础上,提出一种基于格规约辅助的GMD-TH预编码方案。该方案采用基于格规约的算法对信道矩阵进行优化,经过优化的信道矩阵其列向量之间具有更好的正交性并且向量的长度更短,并且采用优化的信道矩阵提高了GMD-TH预编码MIMO系统的分集增益。仿真结果表明:相比于传统的线性预编码方案,该预编码方案有效地提高了MIMO分集增益,相同误码率下,信噪比降低3 dB以上,具有实用价值。
