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Sampling from the lattice Gaussian distribution has emerged as a key problem in coding and decoding while Markov chain Monte Carlo (MCMC) methods from statistics offer an effective way to solve it. In this paper, the sliced lattice Gaussian sampling algorithm is proposed to further improve the convergence performance of the Markov chain targeting at lattice Gaussian sampling. We demonstrate that the Markov chain arising from it is uniformly ergodic, namely, it converges exponentially fast to the stationary distribution. Meanwhile, the convergence rate of the underlying Markov chain is also investigated, and we show the proposed sliced sampling algorithm entails a better convergence performance than the independent Metropolis-Hastings-Klein (IMHK) sampling algorithm. On the other hand, the decoding performance based on the proposed sampling algorithm is analyzed, where the optimization with respect to the standard deviation $\sigma >0$ of the target lattice Gaussian distribution is given. After that, a judicious mechanism based on distance judgement and dynamic updating for choosing $\sigma $ is proposed for a better decoding performance. Finally, simulation results based on multiple-input multiple-output (MIMO) detection are presented to confirm the performance gain by the convergence enhancement and the parameter optimization.

In a majority of research on covert communications, knowledge about channel state information (CSI) of main channel and/or warden channel is assumed to be known or partially known. However, a covert user may not afford to perform channel estimation in practice, and acquiring the warden’s CSI is even impossible. In this paper, we investigate covert communications over non-coherent Rayleigh fading channels, in both i.i.d. fast fading and slow fading cases. We observe that the purpose of covert communication in many scenarios is to hide the existence of the sender, not the receiver. Therefore, we allow the receiver to work in full-duplex mode such that it can emit artificial noise (AN) while receiving signals simultaneously. We analyse the achievable covert rates with fixed and varying AN power and show that in both fast and slow fading cases, it is possible to achieve a positive covert rate. For the slow fading case, we further extend the proposed strategy to a multi-user scenario, in which multiple other users share the same spectral resource and cause interference at the warden. Extensive simulations are performed to verify the correctness of our analysis, which provide new insights on the AN design problem in non-coherent channels.

Synthesizing cost-effective, highly active and stable electrocatalysts for hydrogen evolution reaction (HER) is incredibly critical for scalable hydrogen production through electrochemical water splitting, yet it remains a significant challenge. Noble metal-based materials are generally considered the most excellent electrocatalysts for HER, but their scarcity and high cost impede their comprehensive application. Herein, an auspicious strategy to couple highly active precious metals with transition metals as excellent HER catalysts is presented, which not only can effectively reduce the dosage of the precious metals, but also greatly improve the performance of catalysts. The desired electrocatalysts, based on nitrogen-doped carbon-RhNi alloy nanoparticles anchored on reduced graphene oxide nanosheets (NC-RhNi/rGO), are obtained from pyrolysis of bimetallic RhNi-MOFs/GO precursor. The as-prepared NC-RhNi/rGO catalyst achieves noticeable HER performance, with overpotentials of 37 and 34 mV at the current density of 10 mA cm−2 in 1.0 M KOH and 0.5 M H2SO4, respectively, which are better than that of commercial Pt/C. Experimental results reveal that the superior activities are a benefit of the synergistic effect of bimetallic alloy and the collective effects of unique architecture, where the synergistic effect can facilitate electron transfer and the unique architecture provides rich active sites. This work provides a promising approach for the synthesis of highly efficient nanocomposite electrocatalysts for HER.

Lattices are a popular field of study in mathematical research, but also in more practical areas like cryptology or multiple-input/multiple-output (MIMO) transmission. In mathematical theory, most often lattices over real numbers are considered. However, in communications, complex-valued processing is usually of interest. Besides, by the use of dual-polarized transmission as well as by the combination of two time slots or frequencies, four-dimensional (quaternion-valued) approaches become more and more important. Hence, to account for this fact, well-known lattice algorithms and related concepts are generalized in this work. To this end, a brief review of complex arithmetic, including the sets of Gaussian and Eisenstein integers, and an introduction to quaternion-valued numbers, including the sets of Lipschitz and Hurwitz integers, are given. On that basis, generalized variants of two important algorithms are derived: first, of the polynomial-time LLL algorithm, resulting in a reduced basis of a lattice by performing a special variant of the Euclidean algorithm defined for matrices, and second, of an algorithm to calculate the successive minima - the norms of the shortest independent vectors of a lattice - and its related lattice points. Generalized bounds for the quality of the particular results are established and the asymptotic complexities of the algorithms are assessed. These findings are extensively compared to conventional real-valued processing. It is shown that the generalized approaches outperform their real-valued counterparts in complexity and/or quality aspects. Moreover, the application of the generalized algorithms to MIMO communications is studied, particularly in the field of lattice-reduction-aided and integer-forcing equalization.

Despite several works on secrecy coding for fading and MIMO wiretap channels from an error probability perspective, the construction of information-theoretically secure codes over such channels remains an open problem. In this paper, we consider a fading wiretap channel model where the transmitter has only partial statistical channel state information. Our channel model includes static channels, i.i.d. block fading channels, and ergodic stationary fading with fast decay of large deviations for the eavesdropper's channel. We extend the flatness factor criterion from the Gaussian wiretap channel to fading and MIMO wiretap channels, and establish a simple design criterion where the normalized product distance / minimum determinant of the lattice and its dual should be maximized simultaneously. Moreover, we propose concrete lattice codes satisfying this design criterion, which are built from algebraic number fields with constant root discriminant in the single-antenna case, and from division algebras centered at such number fields in the multiple-antenna case. The proposed lattice codes achieve strong secrecy and semantic security for all rates $R, Comment: 23 pages (double column), 3 figures. Final version. Appendix II has been removed from the final version due to a bug in Corollary II.5

Cache-aided content delivery is studied in a multi-server system with $P$ servers and $K$ users, each equipped with a local cache memory. In the delivery phase, each user connects randomly to any $\rho$ out of $P$ servers. Thanks to the availability of multiple servers, which model small base stations with limited storage capacity, user demands can be satisfied with reduced storage capacity at each server and reduced delivery rate per server; however, this also leads to reduced multicasting opportunities compared to a single server serving all the users simultaneously. A joint storage and proactive caching scheme is proposed, which exploits coded storage across the servers, uncoded cache placement at the users, and coded delivery. The delivery \textit{latency} is studied for both \textit{successive} and \textit{simultaneous} transmission from the servers. It is shown that, with successive transmission the achievable average delivery latency is comparable to that achieved by a single server, while the gap between the two depends on $\rho$, the available redundancy across servers, and can be reduced by increasing the storage capacity at the SBSs., Comment: Published in WCNC, 2018

Sampling from the lattice Gaussian distribution is emerging as an important problem in coding and cryptography. In this paper, the classic Metropolis-Hastings (MH) algorithm from Markov chain Monte Carlo (MCMC) methods is adapted for lattice Gaussian sampling. Two MH-based algorithms are proposed, which overcome the restriction suffered by the default Klein's algorithm. The first one, referred to as the independent Metropolis-Hastings-Klein (MHK) algorithm, tries to establish a Markov chain through an independent proposal distribution. We show that the Markov chain arising from the independent MHK algorithm is uniformly ergodic, namely, it converges to the stationary distribution exponentially fast regardless of the initial state. Moreover, the rate of convergence is explicitly calculated in terms of the theta series, leading to a predictable mixing time. In order to further exploit the convergence potential, a symmetric Metropolis-Klein (SMK) algorithm is proposed. It is proven that the Markov chain induced by the SMK algorithm is geometrically ergodic, where a reasonable selection of the initial state is capable to enhance the convergence performance., Submitted to IEEE Transactions on Information Theory

Zinc hydroxystannate ( ZHS) coated magnesium salt whisker (M-HOS) was synthesized via co-precipitation method and was applied to flexible PVC materials. Zinc hydroxystannate coated M-HOS flame retardants were characterized by XRD and ESEM, the effect of ZHS coated M-HOS to the thermal and flame retardant properties of flexible PVC are analyzed by thermal analysis, limited oxygen index (LOI) and cone calorimeter test. Results showed that ZHS coating is asymmetrical, and the fire retardation and smoke suppressant properties of PVC filled with zinc hydroxystannate coated M-HOS were favorable.

There exist two issues among popular lattice reduction (LR) algorithms that should cause our concern. The first one is Korkine-Zolotarev (KZ) and Lenstra-Lenstra-Lovasz (LLL) algorithms may increase the lengths of basis vectors. The other is KZ reduction suffers much worse performance than Minkowski reduction in terms of providing short basis vectors, despite its superior theoretical upper bounds. To address these limitations, we improve the size reduction steps in KZ and LLL to set up two new efficient algorithms, referred to as boosted KZ and LLL, for solving the shortest basis problem (SBP) with exponential and polynomial complexity, respectively. Both of them offer better actual performance than their classic counterparts, and the performance bounds for KZ are also improved. We apply them to designing integer-forcing (IF) linear receivers for multi-input multi-output (MIMO) communications. Our simulations confirm their rate and complexity advantages., MATLAB codes are available in: https://codeocean.com/2017/06/22/boosted-korkine-zolotarev-lpar-kz-rpar-and-lenstra-ndash-lenstra-ndash-lov%C3%A1sz-lpar-lll-rpar-algorithms/code

In this paper, the static constitutive model of rubber damping materials, the equipment needed in experiment and the method of experiment design optimization are studied, providing new experiment design and theoretical basis for accurate design and application of vehicle rubber damper.

In the constant-temperature indoor environment, the static principles of rubber materials for vibration damping in vehicles and the load and application scope of the experiments are studied in this paper. Basic experiments are carried out for common rubber materials in vehicle system by using advanced experimental equipment.

In this paper, we consider the problem of polar coding for block fading channels without any instantaneous channel state information (CSI). We first decompose a block fading channel of $T_{c}$ symbols per coherent interval into $T_{c}$ binary-input sub-channels in a mutual-information-preserving way, and then design a multilevel (MLC) polar coding scheme for them. The proposed scheme achieves the ergodic mutual information of binary-input block fading channels with only channel distribution information (CDI). Simulations results are presented to compare the performance of the proposed MLC scheme and polar codes designed for i.i. d. fading channels with interleaving, which can provide some guidance for practical designs.

In this paper we show that any sequence of infinite lattice constellations which is good for the unconstrained Gaussian channel can be shaped into a capacity-achieving sequence of codes for the power-constrained Gaussian channel under lattice decoding and non-uniform signalling. Unlike previous results in the literature, our scheme holds with no extra condition on the lattices (e.g. quantization-goodness or vanishing flatness factor), thus establishing a direct implication between AWGN-goodness, in the sense of Poltyrev, and capacity-achieving codes. Our analysis uses properties of the discrete Gaussian distribution in order to obtain precise bounds on the probability of error and achievable rates. In particular, we obtain a simple characterization of the finite-blocklength behavior of the scheme, showing that it approaches the optimal dispersion coefficient for \textit{high} signal-to-noise ratio. We further show that for \textit{low} signal-to-noise ratio the discrete Gaussian over centered lattice constellations can not achieve capacity, and thus a shift (or "dither") is essentially necessary., Comment: 20 pages, 2 figures - added two sections (IV-C and IV-D) on finite dithers and reduced peak power

We consider the problem of polar coding for secure communications over the two-way wiretap channel, where two legitimate users communicate with each other simultaneously while a passive eavesdropper overhears a combination of their exchanged signals. The legitimate users wish to design a cooperative jamming code such that the interference between their codewords can jam the eavesdropper. In this paper, we design a polar coded cooperative jamming scheme that achieves the whole secrecy rate region of the general two-way wiretap channel under the strong secrecy criterion. The chaining method is used to make proper alignment of polar indices. The randomness required to be shared between two legitimate users is treated as a limited resource and we show that its rate can be made negligible by increasing the blocklength and the number of chained blocks. For the special case when the eavesdropper channel is degraded with respect to the legitimate ones, a simplified scheme is proposed which can simultaneously ensure reliability and weak secrecy within a single transmission block. An example of the binary erasure channel case is given to demonstrate the performance of our scheme., 28 pages, 7 figures

In this work, an explicit wiretap coding scheme based on polar lattices is proposed to achieve the secrecy capacity of the additive white Gaussian noise (AWGN) wiretap channel. Firstly, polar lattices are used to construct secrecy-good lattices for the mod-$\Lambda_s$ Gaussian wiretap channel. Then we propose an explicit shaping scheme to remove this mod-$\Lambda_s$ front end and extend polar lattices to the genuine Gaussian wiretap channel. The shaping technique is based on the lattice Gaussian distribution, which leads to a binary asymmetric channel at each level for the multilevel lattice codes. By employing the asymmetric polar coding technique, we construct an AWGN-good lattice and a secrecy-good lattice with optimal shaping simultaneously. As a result, the encoding complexity for the sender and the decoding complexity for the legitimate receiver are both O(N logN log(logN)). The proposed scheme is proven to be semantically secure., Comment: Submitted to IEEE Trans. Information Theory, revised. This is the authors' own version of the paper

We study the problem of recovering an $s$-sparse signal $\mathbf{x}^{\star}\in\mathbb{C}^n$ from corrupted measurements $\mathbf{y} = \mathbf{A}\mathbf{x}^{\star}+\mathbf{z}^{\star}+\mathbf{w}$, where $\mathbf{z}^{\star}\in\mathbb{C}^m$ is a $k$-sparse corruption vector whose nonzero entries may be arbitrarily large and $\mathbf{w}\in\mathbb{C}^m$ is a dense noise with bounded energy. The aim is to exactly and stably recover the sparse signal with tractable optimization programs. In this paper, we prove the uniform recovery guarantee of this problem for two classes of structured sensing matrices. The first class can be expressed as the product of a unit-norm tight frame (UTF), a random diagonal matrix and a bounded columnwise orthonormal matrix (e.g., partial random circulant matrix). When the UTF is bounded (i.e. $\mu(\mathbf{U})\sim1/\sqrt{m}$), we prove that with high probability, one can recover an $s$-sparse signal exactly and stably by $l_1$ minimization programs even if the measurements are corrupted by a sparse vector, provided $m = \mathcal{O}(s \log^2 s \log^2 n)$ and the sparsity level $k$ of the corruption is a constant fraction of the total number of measurements. The second class considers randomly sub-sampled orthogonal matrix (e.g., random Fourier matrix). We prove the uniform recovery guarantee provided that the corruption is sparse on certain sparsifying domain. Numerous simulation results are also presented to verify and complement the theoretical results., Comment: 12 pages, double column. Accepted for publication in the IEEE Transactions on Signal Processing

Explicit coding schemes are proposed to achieve the rate-distortion function of the Heegard-Berger problem using polar codes. Specifically, a nested polar code construction is employed to achieve the rate-distortion function for the doubly-symmetric binary sources when the side information may be absent. The nested structure contains two optimal polar codes for lossy source coding and channel coding, respectively. Moreover, a similar nested polar lattice construction is employed when the source and the side information are jointly Gaussian. The proposed polar lattice is constructed by nesting a quantization polar lattice and a capacity-achieving polar lattice for the additive white Gaussian noise channel.

Adaptive sensing has the potential to achieve near optimal performance by using current measurements to design subsequential sensing vectors. Existing adaptive sensing methods are usually based on recursive bisection or known structures of certain sparse representations. They suffer from either wasting extra measurements for detecting large coefficients, or missing these coefficients because of violations of these structures. In this paper, intra-scale variable density sampling (InVDS) is presented to capture the heterogeneous property of coefficients. First, Latin hypercube sampling with good uniformity is employed to find areas containing large coefficients. Then, the neighborhoods of $K$ largest coefficients are measured according to the block-sparsity or clustering property. Finally, the denoising-based approximate message passing algorithm is introduced to enhance the performance of image reconstruction. The probability that our sampling method fails to obtain large coefficients is analyzed. The superiority of InVDS is validated by numerical experiments with wavelet, discrete cosine, and Hadamard transforms.

Sampling from the lattice Gaussian distribution is emerging as an important problem in coding and cryptography. In this paper, the conventional Gibbs sampling algorithm is demonstrated to be geometrically ergodic in tackling with lattice Gaussian sampling, which means its induced Markov chain converges exponentially fast to the stationary distribution. Moreover, as the exponential convergence rate is dominated by the spectral radius of the forward operator of the Markov chain, a comprehensive analysis is given and we show that the convergence performance can be further enhanced by usages of blocked sampling strategy and choices of selection probabilities.

Green buildings are vital to sustainability. In order to make Singapore’s landscape green, the BCA Green Mark is launched to recognize a building’s sustainability performance and evaluate its environmental impact. The author discusses the benefit of green buildings and how Singapore become the leader in this field.

The safety is a prerequisite for the nuclear power plants’ operation. Various measures have been considered at the design stage to ensure the reliability of the NPPs. During the nuclear power plants’ operation, equipment reliability management is one of the primary means to ensure NPPs operate safety. RCM, Reliability-centered Maintenance, an important method for the equipment reliability management in NPPs, can be used to complete FMEA analysis for the systems and components, and develop or optimize maintenance strategies to ensure the effectiveness of preventive maintenance strategy according to RCM decision logic. At the same time, it can be used to find the insufficient of the design, improve the control logic and layout. This article describes the RCM analysis process, illustrates the application and effectiveness of the RCM analysis in maintenance and control optimization combined with the practice of nuclear power plants.

In this paper, we propose a low-complexity, secrecy capacity achieving polar coding scheme for the cognitive interference channel with confidential messages (CICC) under the strong secrecy criterion. Existing polar coding schemes for interference channels rely on the use of polar codes for the multiple access channel, the code construction problem of which can be complicated. We show that the whole secrecy capacity region of the CICC can be achieved by simple point-to-point polar codes due to the cognitivity, and our proposed scheme requires the minimum rate of randomness at the encoder.

Vector perturbation (VP) precoding is a promising technique for multiuser communication systems operating in the downlink. In this work, we introduce a hybrid framework to improve the performance of lattice reduction (LR) aided precoding in VP. First, we perform a simple precoding using zero forcing (ZF) or successive interference cancellation (SIC) based on a reduced lattice basis. Since the signal space after LR-ZF or LR-SIC precoding can be shown to be bounded to a small range, then along with sufficient orthogonality of the lattice basis guaranteed by LR, they collectively pave the way for the subsequent application of an approximate message passing (AMP) algorithm, which further boosts the performance of any suboptimal precoder. Our work shows that the AMP algorithm can be beneficial for a lattice decoding problem whose data symbols lie in integers $\mathbb{Z}$ and entries of the lattice basis may bot be i.i.d. Gaussian. Numerical results confirm the low-complexity AMP algorithm can improve the symbol error rate (SER) performance of LR aided precoding significantly. Lastly, the hybrid scheme is also proved effective when solving the data detection problem of massive MIMO systems without using LR., Comment: under revision in IEEE Trans. Signal Processing

We consider joint channel estimation and faulty antenna detection for massive multiple-input multiple-output (MIMO) systems operating in time-division duplexing (TDD) mode. For systems with faulty antennas, we show that the impact of faulty antennas on uplink (UL) data transmission does not vanish even with unlimited number of antennas. However, the signal detection performance can be improved with a priori knowledge on the indices of faulty antennas. This motivates us to propose the approach for simultaneous channel estimation and faulty antenna detection. By exploiting the fact that the degrees of freedom of the physical channel matrix are smaller than the number of free parameters, the channel estimation and faulty antenna detection can be formulated as an extended atomic norm denoising problem and solved efficiently via the alternating direction method of multipliers (ADMM). Furthermore, we improve the computational efficiency by proposing a fast algorithm and show that it is a good approximation of the corresponding extended atomic norm minimization method. Numerical simulations are provided to compare the performances of the proposed algorithms with several existing approaches and demonstrate the performance gains of detecting the indices of faulty antennas., Accepted for publication in the IEEE Transactions on Vehicular Technology

The nouniformity of rock and soil materials and differences of boundary conditions caused the differentiation of stress field, together with the elastic-plastic characteristics of sliding zone material control the progressive unstable failure process. In this paper, The analysis of engineering example shows that the mechanical criterion is reasonable to judge the state of progressive slope evolution.

The unstable failure of rock and soil slope was a progressive evolution process from local failure to total failure. The no-uniformity of rock and soil materials and differences of boundary conditions caused the discrepancy of stress field, together with the elastic-plastic characteristics of the sliding zone which controls the progressive unstable failure process. In this paper, any point of slop sliding zone was taken for the research object. On basis of limit slice method, the mechanical condition of slice was considered as a plane strain problem. According to Mohr-Coulomb linear failure criterion the stress state of a point is obtained with selecting stress function to establish the mechanical criterion of progressive slope failure. The analysis of engineering example shows that the mechanical criterion is reasonable to estimate the state of progressive slope evolution.

City, is consisting of a series continuous or intermittent public space images, and every image for each of our people living in the city is varied: may be as awesome as forbidden city Meridian Gate, like Piazza San Marco as a cordial and pleasant space and might also be like Manhattan district of New York, which makes people excited and enthusiastic. To see why, people have different feelings because the public urban space ultimately belongs to democratic public space, people live and have emotions in it. In such domain, people can not only be liberated, free to enjoy the pleasures of urban public space, but also enjoy urban life which is brought by the city's charm through highlighting the vitality of the city with humanism atmosphere. To a conclusion, no matter how ordinary the city is, a good image of urban space can also bring people pleasure.

This article demonstrated the necessity of building energy-saving design in our country. Analyzed the advanced building energy conservation technology applied to the BedZED in United Kingdom, such as solar energy technology, ventilation technology and water-saving technology. In accordance with the practice in Residential area in China, the realization way of building energy conservation technology is presented, in order to achieve the aim of sustainable development.

The thesis analyses the early stage of the planning and design in Taiyuan xicun renovation project from the green building perspective. It summarizes the strengths and shortages on the basis of Four Conservations and One Protection (area conservation, energy conservation, water conservation, material conservation and environmental protection). By analyzing the problems in planning and designing modern residential area, this thesis aims to provide some suggestions to the green building idea.

This paper introduces a soldering defect inspection system for a special integrated circuit board aided by the computer vision. Space occluder is fixed on this special integrated circuit board, which makes the light blocked from the CCD camera to the chip pins to be inspected. This system can inspect the light blocked soldering defects of the chip pins through the structure design of hardware system and the software system. It is a cheap but automatic soldering defect inspecting system, and can do the soldering defect detection instead of manual visual inspection, and improve the detection speed and stability.

Integer coefficient selection is an important decoding step in the implementation of compute-and-forward (C-F) relaying scheme. Choosing the optimal integer coefficients in C-F has been shown to be a shortest vector problem (SVP) which is known to be NP hard in its general form. Exhaustive search of the integer coefficients is only feasible in complexity for small number of users while approximation algorithms such as Lenstra-Lenstra-Lovasz (LLL) lattice reduction algorithm only find a vector within an exponential factor of the shortest vector. An optimal deterministic algorithm was proposed for C-F by Sahraei and Gastpar specifically for the real valued channel case. In this paper, we adapt their idea to the complex valued channel and propose an efficient search algorithm to find the optimal integer coefficient vectors over the ring of Gaussian integers and the ring of Eisenstein integers. A second algorithm is then proposed that generalises our search algorithm to the Integer-Forcing MIMO C-F receiver. Performance and efficiency of the proposed algorithms are evaluated through simulations and theoretical analysis., IEEE Transactions on Wireless Communications, to appear.12 pages, 8 figures

In this paper, we design polar codes and polar lattices for i.i.d. fading channels when the channel state information is only available to the receiver. For the binary input case, we propose a new design of polar codes through single-stage polarization to achieve the ergodic capacity. For the non-binary input case, polar codes are further extended to polar lattices to achieve the egodic Poltyrev capacity, i.e., the capacity without power limit. When the power constraint is taken into consideration, we show that polar lattices with lattice Gaussian shaping achieve the egodic capacity of fading channels. The coding and shaping are both explicit, and the overall complexity of encoding and decoding is $O(N \log^2 N)$., Comment: 22 pages, 9 figures, extended version of ISIT 2016 submission. Some simulation results have been updated

Based on lattice Gaussian distributions and ideal lattices, we present a unified framework of lattice coding to achieve the channel capacity and secrecy capacity of wireless channels in the presence of Gaussian noise. The standard additive white Gaussian-noise (AWGN) channel, block fading channel, and multi-input multi-output (MIMO) fading channel are considered, which form a hierarchy of increasingly challenging problems in coding theory. To achieve channel capacity, we apply Gaussian shaping to a suitably defined good lattice for channel coding. To achieve secrecy capacity, we use a secrecy-good lattice nested with a coding lattice.

In this work we show that algebraic lattices con- structed from error-correcting codes achieve the ergodic capacity of the fading channel. The main ingredients for our construction are a generalized version of the Minkowski-Hlawka theorem and shaping techniques based on the lattice Gaussian distribution. The structure of the ring of integers in a number field plays an important role in the proposed construction. In the case of independent and identically distributed fadings, the lattices considered exhibit full diversity and an exponential decay of the probability of error with respect to the blocklength.

As a key sampling scheme in Markov chain Monte Carlo (MCMC) methods, Gibbs sampling is widely used in various research fields due to its elegant univariate conditional sampling, especially in tacking with multidimensional sampling systems. In this paper, a Gibbs-based sampler named as symmet- ric Metropolis-within-Gibbs (SMWG) algorithm is proposed for lattice Gaussian sampling. By adopting a symmetric Metropolis- Hastings (MH) step into the Gibbs update, we show the Markov chain arising from it is geometrically ergodic, which converges exponentially fast to the stationary distribution. Moreover, by optimizing its symmetric proposal distribution, the convergence efficiency can be further enhanced.

According to the durability test results of pen cylinders, including failure modes and fatigue life data, life distribution of pen cylinder is studied. The parameters of Weibull distribution of pen cylinder are estimated by least square method. Using Weibull distribution test, the goodness-of-fit test of the pen cylinder life distribution is carried out. Results of goodness-of-fit test show fatigue life distribution of pen cylinder complies with Weibull distribution with two parameters.

In the past, two main approaches for the purpose of authentication, including information-theoretic authentication codes and complexity-theoretic message authentication codes (MACs), were almost independently developed. In this paper, we propose a new cryptographic primitive, namely, artificial-noise-aided MACs (ANA-MACs), which can be considered as both computationally secure and information-theoretically secure. For ANA-MACs, we introduce artificial noise to interfere with the complexity-theoretic MACs and quantization is further employed to facilitate packet-based transmission. With a channel coding formulation of key recovery in the MACs, the generation of standard authentication tags can be seen as an encoding process for the ensemble of codes, where the shared key between Alice and Bob is considered as the input and the message is used to specify a code from the ensemble of codes. Then, we show that the introduction of artificial noise in ANA-MACs can be well employed to resist the key recovery attack even if the opponent has an unlimited computing power. Finally, a pragmatic approach for the analysis of ANA-MACs is provided, and we show how to balance the three performance metrics, including the completeness error, the false acceptance probability, and the conditional equivocation about the key. The analysis can be well applied to a class of ANA-MACs, where MACs with Rijndael cipher are employed., 12 pages, 4 figures, submitted for possible publication

In this paper, we provide a comprehensive survey on designs and analyses of various relay-destination transceiving schemes, such as zero-forcing (ZF), minimum mean squared error (MMSE), and maximum information rate (MIR) criteria, in multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying systems. In the first part of the paper, we suggest a new framework for the transceiver designs utilizing a decomposable property of the error covariance matrix to give a general insight on the system and make the analysis more tractable. Then, in the second part of the paper, we provide an in-depth analysis on their diversity performance. Our analysis embraces two different scenarios, namely, the diversity-multiplexing tradeoff (DMT) and the diversity-rate tradeoff (DRT). First, we derive compact closed-form expressions for the DMT through tight upper and lower bounds. Then, we observe that while our DMT analysis accurately predicts performance of the ZF and MIR schemes, the MMSE-based designs exhibit a complicated rate-dependent behavior and, thus, are very unpredictable via DMT for finite rate cases. Thus, second, we highlight this interesting observation and characterize the diversity of the MMSE schemes at all finite rates. This leads to closed-form expressions for the DRT which reveals relationship between diversity, spectral efficiency, and the number of antennas at each node. The DRT analysis compliments our work on DMT, and thus, the paper provides a complete understanding on the diversity of MIMO AF relaying systems.

The reliability of the pneumatic cylinder was investigated by routine life test. The results show that the failures of the pneumatic cylinder can be described as a Weibull distribution and fatigue fracture of the aluminum end cap and the head of install bolt is the major failure for the pneumatic cylinder. The pneumatic cylinder life distribution parameters were estimated by the median rank method in combination with maximum likelihood method. The distribution model for the reliability of the pneumatic cylinder was also proposed here.

Measurement and control system is the key equipment for testing and analyzing of the dynamic characteristics for a nonlinear absorber.It is the necessary means of accomplishing to design the rationalization of the nonlinear absorber. This article has conducted the detailed research in the new development of absorber test equipment to the desing of system structure, The constituent of software system, and The process design, and The development of the computer program based on virtual techniques. Debugging and running this software system have shown that the precision and reliability of it have been proved.

Development of special rubber shock absorber test equipment for vehicle will become very important, this equipment can test and analysis of dynamic characteristics for rubber shock absorber.The paper discusses the problem on optimum design of electro-hydraulic servo system which drives the vibration set. A closed system for controlling mechanical position or motion using feedback from the electro-hydraulic servo valve of the device as an input has been used in hydraulic servo system. The maximum region of design parameters has been defined for hydraulic servo cylinder as a core element of the electro-hydraulic exciting system. Established the mathematical model of the system, and the dynamic characteristics of the hydraulic servo cylinder are investigated by utilizing the simulation software MATLAB. The results of computer emulation show that this method is practical.

Antenna arrays that incorporate MIMO technology for indoor–outdoor network interconnection on the same terminal, i.e., for DCS 1800, PCS 1900, WCDMA, 3G, 802.11a/b/g, Bluetooth®, ZigBee®, WiMAX™, and UWB standards, are proposed. Staircase profile printed circuit antennas, monopoles (PCM), and slots (PCS) with VSWR < 2 bandwidth mainly from 1.12 to 10.1 GHz are previously designed, simulated, constructed, and measured as antenna elements for those arrays. For comparison, prototypes for two-element PCM and PCS MIMO arrays have been constructed and measured. The choice should be made according to the directivity required by the final application and portable device size. For the worst signal interference case, the operational bandwidth ranges from 1.5 to 9.9 GHz and from 1.7 to 11.4 GHz for the PCM and the PCS MIMO arrays, respectively. VSWR is basically below two, average capacity loss 0.32 bps/Hz with respect to the ideal uncorrelated (2,2) case and envelope correlation lower than 20 dB. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:889–895, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25047

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 Processing

Recently, we have developed a PHYsical layer Phase Challenge-Response Authentication Scheme (PHY-PCRAS) for independent multicarrier transmission. In this paper, we make a further step by proposing a novel artificial-noise-aided PHY-PCRAS (ANA-PHY-PCRAS) for practical orthogonal frequency division multiplexing (OFDM) transmission, where the Tikhonov-distributed artificial noise is introduced to interfere with the phase-modulated key for resisting potential key-recovery attacks whenever a static channel between two legitimate users is unfortunately encountered. Then, we address various practical issues for ANA-PHY-PCRAS with OFDM transmission, including correlation among subchannels, imperfect carrier and timing recoveries. Among them, we show that the effect of sampling offset is very significant and a search procedure in the frequency domain should be incorporated for verification. With practical OFDM transmission, the number of uncorrelated subchannels is often not sufficient. Hence, we employ a time-separated approach for allocating enough subchannels and a modified ANA-PHY-PCRAS is proposed to alleviate the discontinuity of channel phase at far-separated time slots. Finally, the key equivocation is derived for the worst case scenario. We conclude that the enhanced security of ANA-PHY-PCRAS comes from the uncertainty of both the wireless channel and introduced artificial noise, compared to the traditional challenge-response authentication scheme implemented at the upper layer., 33 pages, 13 figures, submitted for possible publication

This paper is aimed to investigate the effect of roller working on the torsional fatigue properties of a typical low carbon steel referring by the resutls of FEM analysis. Three types of specimens had been prepared with plastic deformation value of 0, 0.5 and 1.0mm, respectively. The main results obtained in this study are as follows: (1) The torsional fatigue strength of roller-worked specimen with 1.0mm plastic deformation is increased more than twice of that of non-rollerworked specimens. (2) Surface hardness of roller worked specimen is much higher than that of the non-roller worked one, and compressed and elongated structure is formed at the notch bottom of the specimen. (3) Crack length along the axial direction of roller worked specimens is longer than that of the non-roller worked specimen, and plural cracks initiated and propagated in the roller worked specimens. (4) The residual stress distribution at the specimen’s notch bottom was analysed using FEM analysis and it is verified the same tendency as the experimental results.

Three kinds of materials, pure aluminum (Al1050), carbon steel (S25C) and eutectoid steel (NHH) with V-notch are used in this study to compare the effect of roller working on the fatigue properties among the test materials. As the result, all of the fatigue strengths are improved after roller working and the optimum deformation values exist for every test materials. Fiberized microstructure at the notch bottom, work hardening and compressive residual stress caused by roller working are considered as the main reasons for the fatigue strength improvement. The highest fatigue strength improvement of Al1050, S25C and NHH was 30%, 118% and 155%, respectively. The optimum fatigue improvement of NHH is the highest and it is much higher than that of Al1050, and the optimum deformation value of Al1050 is much lower than that of the other materials. Moreover, the roller working effect is much remarkable for the materials with better hardenability.

In this paper, design problems on rotating cone reactor have been studied and dynamics problems have been analyzed in detail, kinematics differential equation of mixture in rotating cone reactor and simulation model has been established. Rotating cone reactor prototype which was established preliminarily has been optimized with simulation software. Dynamics analysis and simulation is of great significance in raising the efficiency of BIO-FUEL-OIL flash pyrolysis rotating cone reactor, control production process reliably, and even optimizing design value and physical dimension which is reasonable in design and reducing the cost of product development process.

In this paper, we propose a new class of lattices constructed from polar codes, namely polar lattices, to achieve the capacity $\frac{1}{2}\log(1+\SNR)$ of the additive white Gaussian-noise (AWGN) channel. Our construction follows the multilevel approach of Forney \textit{et al.}, where we construct a capacity-achieving polar code on each level. The component polar codes are shown to be naturally nested, thereby fulfilling the requirement of the multilevel lattice construction. We prove that polar lattices are \emph{AWGN-good}. Furthermore, using the technique of source polarization, we propose discrete Gaussian shaping over the polar lattice to satisfy the power constraint. Both the construction and shaping are explicit, and the overall complexity of encoding and decoding is $O(N\log N)$ for any fixed target error probability., Comment: full version of the paper to appear in IEEE Trans. Communications

This paper proposes a compact 10 dB broadband directional coupler, which is constructed from two parallel E-plane rectangular waveguide with three apertures and three metallic posts attached on the apertures. The design has been simulated using Computer Simulation Technology (CST) Microwave Studio 3D simulator, the simulation shows that return loss of the compact directional coupler is below -25 dB between 7.7 GHz and 12.1 GHz, the coupling is 10.1±0.8 dB and the isolation is better than 38 dB in a fractional band of 44%. In order to measure and match the directional coupler, a waveguide-to-waveguide transition has been proposed, whose return loss is below -27 dB in the design band.

A five ports ridge waveguide power divider with compact sizes is proposed and analyzed in this paper. The whole structure of this power divider is symmetrical configuration, so it can easily dominate the phase and amplitude consistence of two output ports. This type of power divider can provide good phase and amplitude consistence between two output ports with low return loss, low insertion loss, high isolation and compact size in C-band. The simulation shows that return loss of the compact divider is below -18 dB between 2.8 GHz and 3.6 GHz, the insertion loss is lower than 0.1 dB, the isolation between two output ports is better than 20 dB, the phase and the amplitude of two output ports is absolutely consistent. In order to match the ridge waveguide, this paper presents the design of a transition from coaxial line to ridge waveguide.