Comparative Study of SVD and QRS in Closed-Loop Beamforming Systems

We compare two closed-loop beamforming algorithms, one based on singular value decomposition (SVD) and the other based on equal diagonal QR decomposition (QRS). SVD has the advantage of parallelizing the MIMO channel, but each of the sub-channels has different gain. QRS has the advantage of having equal diagonal value for the decomposed channel, but the subchannels are not fully parallelized, hence requiring successive interference cancellation or other techniques to perform decoding. We consider a closed-loop system where the feedback information is a unitary beamforming matrix. Due to the discrete and limited modulation set, SVD may have inferior performance to QRS when no modulation set selection is performed. However, if the selection of modulation set is performed optimally, we show that SVD can outperform QRS.Comment: Milcom 200

Modulated Unit-Norm Tight Frames for Compressed Sensing

In this paper, we propose a compressed sensing (CS) framework that consists of three parts: a unit-norm tight frame (UTF), a random diagonal matrix and a column-wise orthonormal matrix. We prove that this structure satisfies the restricted isometry property (RIP) with high probability if the number of measurements $m = O(s \log^2s \log^2n)$ for $s$-sparse signals of length $n$ and if the column-wise orthonormal matrix is bounded. Some existing structured sensing models can be studied under this framework, which then gives tighter bounds on the required number of measurements to satisfy the RIP. More importantly, we propose several structured sensing models by appealing to this unified framework, such as a general sensing model with arbitrary/determinisic subsamplers, a fast and efficient block compressed sensing scheme, and structured sensing matrices with deterministic phase modulations, all of which can lead to improvements on practical applications. In particular, one of the constructions is applied to simplify the transceiver design of CS-based channel estimation for orthogonal frequency division multiplexing (OFDM) systems.Comment: submitted to IEEE Transactions on Signal Processin

Towards Top-Down Stereoscopic Image Quality Assessment via Stereo Attention

Stereoscopic image quality assessment (SIQA) plays a crucial role in evaluating and improving the visual experience of 3D content. Existing binocular properties and attention-based methods for SIQA have achieved promising performance. However, these bottom-up approaches are inadequate in exploiting the inherent characteristics of the human visual system (HVS). This paper presents a novel network for SIQA via stereo attention, employing a top-down perspective to guide the quality assessment process. Our proposed method realizes the guidance from high-level binocular signals down to low-level monocular signals, while the binocular and monocular information can be calibrated progressively throughout the processing pipeline. We design a generalized Stereo AttenTion (SAT) block to implement the top-down philosophy in stereo perception. This block utilizes the fusion-generated attention map as a high-level binocular modulator, influencing the representation of two low-level monocular features. Additionally, we introduce an Energy Coefficient (EC) to account for recent findings indicating that binocular responses in the primate primary visual cortex are less than the sum of monocular responses. The adaptive EC can tune the magnitude of binocular response flexibly, thus enhancing the formation of robust binocular features within our framework. To extract the most discriminative quality information from the summation and subtraction of the two branches of monocular features, we utilize a dual-pooling strategy that applies min-pooling and max-pooling operations to the respective branches. Experimental results highlight the superiority of our top-down method in simulating the property of visual perception and advancing the state-of-the-art in the SIQA field. The code of this work is available at https://github.com/Fanning-Zhang/SATNet.Comment: 13 pages, 4 figure

Fire and post-fire performance of circular steel tube confined reinforced concrete columns

[EN] Fire and post-fire behaviours of reinforced concrete columns confined by circular steel tubes, also known as circular steel tube confined reinforced concrete (STCRC) columns, are investigated in this paper. 5 full-scale specimens exposed to fire and 47 specimens after fire exposure were tested. Temperatures across the sections, displacement versus time curves, fire resistance, load versus displacement responses and load-bearing capacities were measured and discussed. A finite element (FE) model was developed using the program ABAQUS, and validated against the test results from the present study. Simplified design methods were proposed for predicting the fire resistance and residual load-bearing capacity of the STCRC columns under and after fire exposure, respectively.The research presented in this paper was sponsored by the National Natural Science Foundation (No. 51508131), the Fundamental Research Funds for the Central Universities (HIT.NSRIF.201860), China Postdoctoral Science Foundation (No.2016M591535); their financial support is highly appreciated.Liu, F.; Yang, H.; Zhang, S. (2018). Fire and post-fire performance of circular steel tube confined reinforced concrete columns. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 787-793. https://doi.org/10.4995/ASCCS2018.2018.7002OCS78779

Behavior of innovative T-shaped multi-partition steel-concrete composite columns under concentric and eccentric compressive loadings

[EN] T-shaped multi-partition steel-concrete composite column, composed of several concrete-filled rectangular steel hollow sections, is considered as an innovative composite member with the ability to accommodate neighboring wall thickness with great easiness. This paper intends to study the behavior of this innovative composite member under concentric and eccentric compressive loadings. A finite element (FE) analysis model accounting for the influences of confinement effects, geometric and material nonlinearities is developed using the program ABAQUS. The ultimate strength and load-strain responses predicted from the analysis are validated against the test results in the experiments conducted by the authors. The comparisons indicate that the FE model reasonably estimates the responses of the concentrically and eccentrically loaded T-shaped multi-partition steel-concrete composite columns. The verified model is then utilized to numerically investigate the working mechanism of the columns. The load distribution between the infilled concrete and the steel tubes and the stress distribution of the concrete during the loading process are analyzed. Moreover, parametric studies are performed to investigate the behavior of T-shaped multi-partition steel-concrete composite columns under different loadings. The studied parameters include steel to concrete area ratio, concrete compressive strength, steel yield strength and load eccentricity. Combined with the experimental results, FE analysis and parametric studies, the design recommendations for T-shaped multi-partition steel-concrete composite columns under different loadings are proposed.The research work reported in this paper were supported by National Key Research and Development Program (2016YFC0701201), and National Natural Science Foundation of China (Grant No. 51578187); their financial supports are highly appreciated.Chen, J.; Zhang, S.; Huang, Z.; Zhang, X.; Guo, L. (2018). Behavior of innovative T-shaped multi-partition steel-concrete composite columns under concentric and eccentric compressive loadings. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 289-296. https://doi.org/10.4995/ASCCS2018.2018.7004OCS28929

On the Capacity Region of Reconfigurable Intelligent Surface Assisted Symbiotic Radios

In this paper, we are interested in reconfigurable intelligent surface (RIS)-assisted symbiotic radio (SR) systems, where an RIS assists a primary transmission by passive beamforming and simultaneously acts as an information transmitter by periodically adjusting its reflecting coefficients. The above modulation scheme innately enables a new multiplicative multiple access channel (M-MAC), where the primary and secondary signals are superposed in a multiplicative and additive manner. To pursue the fundamental performance limits of the M-MAC, we focus on the characterization of the capacity region of such systems. Due to the passive nature of RISs, the transmitted signal of the RIS should satisfy the peak power constraint. Under this constraint at the RIS as well as the average power constraint at the primary transmitter (PTx), we analyze the capacity-achieving distributions of the transmitted signals and characterize the capacity region of the M-MAC. Then, theoretical analysis is performed to reveal insights into the RIS-assisted SR. It is observed that: 1) the capacity region of the M-MAC is strictly convex and larger than that of the conventional TDMA scheme; 2) the secondary transmission can achieve the maximum rate when the PTx transmits the constant envelope signals; 3) and the sum rate can achieve the maximum when the PTx transmits Gaussian signals and the RIS transmits the constant envelope signals. Finally, extensive numerical results are provided to evaluate the performance of the RIS-assisted SR and verify the accuracy of our theoretical analysis

Occurrence and molecular characterization of Cryptosporidium in dogs in Henan Province, China

BACKGROUND: Cryptosporidiosis in dogs has been reported worldwide, involving both asymptomatic and diarrheic dogs. Large-scale surveys of Cryptosporidium infection in dogs have been performed in some countries using differents diagnostic methods. But, few data are available on the infection rate and molecular characteristics of Cryptosporidium spp. in dogs in China. RESULT: In this study, 770 fecal samples from 66 locations in Henan Province were examined. The average Cryptosporidium infection rate was 3.8%, with dogs in kennels having the highest rate of 7.0% (χ(2) = 14.82, P < 0.01). The infection rate was 8.0% in dogs younger than 90 days, which was significantly higher than that in the other age groups (1.1–3.8%;χ(2) = 18.82, P < 0.01). No association was noted between the infection rate and the sex of the dogs. Twenty-nine Cryptosporidium-positive samples were amplified at the small subunit rRNA (SSU rRNA), 70-kDa heat shock protein (HSP70), and actin loci using PCR. Sequence analysis of these amplicons identified only Cryptosporidium canis, which showed 100% identity with the published sequences of the SSU rRNA, HSP70, and actin genes. CONCLUSIONS: Our results confirm that C. canis is popular in the dog population in China, considering the large number of dogs in China and the close contact between dogs and humans, the role of C. canis in the transmission of human cryptosporidiosis warrants attention

Hexa-μ2-acetato-triaqua-μ3-oxido-triiron(III) nitrate acetic acid solvate

The asymmetric unit of the title compound, [Fe3(CH3COO)6O(H2O)3]NO3·CH3COOH, consists of a hexa-μ2-acetato-triaqua-μ3-oxo-triiron(III) macrocation, a nitrate ion and an acetic acid solvent mol­ecule. In the cation, each Fe3+ ion is coordinated by four carboxyl­ate O atoms, one central bridged O atom and one water mol­ecule, resulting in distorted FeO6 octa­hedra. A network of O—H⋯O hydrogen bonds helps to establish the packing