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In this paper, a modified boundary element method (BEM) for time-harmonic scattering computation analysis in two-dimensional (2-D), homogeneous, anisotropic and linear elastic plates is proposed. The aim of modification is to correct the spurious scattering introduced by inevitable model truncation at far-field in the traditional BEM model. The far-field wave displacement fields beyond the truncation points of BEM model are assumed to be the superposition of orthogonal propagating guided wave patterns, and are finally incorporated into BEM equation systems as the modified items to account for the contribution of infinite boundaries traditionally omitted. This method is simple and elegant, which has advantages on dimension reduction and needs no absorption medium or perfectly matched layer to suppress the reflected waves compared to FEM. Also, we can obtain the reflection and transmission coefficients of each mode directly without post-processing. This modified BEM is implemented to solve wave scattering problems due to a cavity-type defect at the interface in an infinite anisotropic multi-layered plate. The formulation is finally validated for several benchmark problems. [ABSTRACT FROM AUTHOR]

Purpose: This paper proposes a recommendation method that mines the semantic relationship between resources and combine it with collaborative filtering (CF) algorithm for crowdsourcing knowledge-sharing communities. Design/methodology/approach: First, structured tag trees are constructed based on tag co-occurrence to overcome the tags' lack of semantic structure. Then, the semantic similarity between tags is determined based on tag co-occurrence and the tag-tree structure, and the semantic similarity between resources is calculated based on the semantic similarity of the tags. Finally, the user-resource evaluation matrix is filled based on the resource semantic similarity, and the user-based CF is used to predict the user's evaluation of the resources. Findings: Folksonomy is a knowledge classification method that is suitable for crowdsourcing knowledge-sharing communities. The semantic similarity between resources can be obtained according to the tags in the folksonomy system, which can be used to alleviate the data sparsity and cold-start problems of CF. Experimental results show that compared with other algorithms, the algorithm in this paper performs better in mean absolute error (MAE) and F1, which indicates that the proposed algorithm yields better performance. Originality/value: The proposed folksonomy-based CF method can help users in crowdsourcing knowledge-sharing communities to better find the resources they need. [ABSTRACT FROM AUTHOR]

An analytical and meshless modeling for solving thickness shear vibration in an infinite piezoelectric quartz resonator with partial non-circular electrodes is proposed. Firstly, two-dimensional scalar differential equations derived by Tiersten and Smythe are adopted and transformed into the polar coordinate system. Secondly, displacement patterns for the electroded and unelectroded regions are assumed as a series of converging and outgoing cylindrical waves in the form of Bessel functions, where radiation conditions at infinity can be satisfied automatically. Finally, circumferential functions at interface are decomposed into Fourier series in order to deal with continuity conditions. It should be stressed that the general formulation proposed in this paper has a higher calculation accuracy and requires no division of the mesh compared to FEM/BEM, which can satisfy continuity conditions in an integrated manner over the whole interface or boundary. Resonance frequencies and mode shapes of different electrode shapes including circular, equilateral triangle, rectangular, elliptical, and pentagonal electrodes are numerically calculated and compared with FEM simulations, which efficiently validate high precision and wide applicability of this method. Utilizing this method, the influence of non-circular electrodes on the working performance of the quartz resonator is investigated systematically. The qualitative analysis and quantitative results obtained in this paper can provide the theoretical guidance for the design, measurement and manufacturing optimization of piezoelectric resonators. [ABSTRACT FROM AUTHOR]

This paper delves into the problem of fixed-time neural network adaptive prescribed performance control for a category of nonstrict-feedback systems with time-varying unknown control coefficients (UCCs). Firstly, two key technical lemmas are proposed. One is to put forward a novel fixed-time stability lemma with a more precise upper-bound estimate of the settling time. The other is to present a new lemma based on a category of type-B Nussbaum functions (TBNFs), which can effectively address the time-varying UCCs in the systems. Secondly, neural networks are employed to approach the uncertain nonlinear terms, and a fixed-time performance function and a nonlinear shifting function are constructed to eliminate the restriction of tracking error in terms of initial condition. Then, to overcome the singularity problem, the switched virtual controllers are designed with the help of the novel fixed-time stability lemma and dynamic surface control technique. It turns out that the tracking error converges to a predefined asymmetric constraint region within a fixed time and the closed-loop system is practically fixed-time stable. Finally, a numerical example and a mass-spring-damper system are provided to verify the effectiveness of the presented design method. [ABSTRACT FROM AUTHOR]

In this paper, a three-dimensional modified boundary element method (BEM) is proposed to solve the guided wave scattering problem by cavity-type flaws in an infinite plate. The aim of modification is to correct the artificial scattering introduced by inevitable modal truncation at far-field in the traditional BEM model. The far-field wave displacement fields beyond the BEM model are assumed to be the summation of orthogonal propagating guided wave patterns, and are finally incorporated into BEM equation sets as the modified items to account for the contribution of infinite boundaries traditionally omitted. With this improvement, the spurious reflected waves are eliminated. The method is formulated for a three-dimensional homogeneous, isotropic, elastic plate and its implementation is discussed in details. The formulation is finally validated for several benchmark problems. [ABSTRACT FROM AUTHOR]

To reduce multiplication operations in convolution of convolutional neural networks (CNNs), there are three widely used convolutional acceleration algorithms, i.e., Winograd, FFT and FFA. However, current accelerators based on these convolutional acceleration algorithms have issues on flexibility and efficiency. Firstly, some accelerators utilized a combination of these acceleration algorithms and employed multiple types of computational units to achieve their respective advantages. As a result, some computational units are left unused when the best-performing unit is working, which causes much area inefficiency. Secondly, current accelerators tend to choose small parameters of these convolutional acceleration algorithms to avoid unacceptable precision loss, as a result, they are hardly to support large kernel sizes and lack of flexibility. Thirdly, these acceleration algorithms are typically presented for 1-stride convolutions, consequently, few implementation considers the acceleration of large-stride convolutions, which is a major restriction to hardware flexibility. This paper proposed a stride-based convolution decomposition method (SCDM) to reform different convolution shapes (i.e., kernel sizes & strides) to an identical pattern. With the aid of SCDM, a Winograd-stretched and hardware-efficient design (WHD) is presented to utilize one uniform computational unit for the acceleration of different convolution shapes, which combines complementary performance advantages on both Winograd F(4,3)andF(4,2) units. Compared to current FFT-based or FFA-based works, WHD can stretch the use range of Winograd and simplify implementation, thereby achieving hardware flexibility and efficiency. Evaluation results show that 34.08%~55.41% operation reduction were achieved on six CNN models, while incurring a slight hardware overhead. [ABSTRACT FROM AUTHOR]

As convolutional neural networks (CNNs) become more and more diverse and complicated, acceleration of CNNs increasingly encounters a bottleneck of balancing performance, energy efficiency, and flexibility in a unified architecture. This paper proposed a Winograd-based highly efficient and dynamically Reconfigurable Accelerator (named WRA) for quickly evolving CNN models. A cost-effective convolution decomposition method (CDW) was proposed, and it extends the application of the fast Winograd algorithm. Based on CDW, a high-throughput and reconfigurable processing element (PE) array was designed to exploit the parallelism of Winograd. Besides, a highly compact memory structure employed four levels of data reuse schemes to achieve maximal data reuse and minimize external bandwidth requirement. Provided with dynamically reconfigurable capability, WRA implements CDW and other convolutions (e.g., standard convolution, depthwise separable convolution, and group convolution) on a unified hardware architecture. The WRA accelerator was implemented on a Xilinx XCVU9P platform running at 330 MHz clock frequency, controlled by a POWER8 processor via a coherent accelerator processor interface (CAPI) interface. At different configurations, WRA can provide 2.2–6.3 TOPS performance for different convolution shapes. The average performance and energy efficiency for VGG16/AlexNet/MobileNetV1/MobileNetV2 are 5288 GOP/s at 151.2 GOPs/W, 3478 GOP/s at 99.4 GOPs/W, 2674 GOP/s at 76.4 GOPs/W, and 2194 GOP/s at 62.7 GOPs/W. It achieves $1.7\times $ – $24\times $ speedup compared with the previous FPGA-based designs. [ABSTRACT FROM AUTHOR]

Highlights • Modified particle filter with Markovian packet dropout and delay is proposed for general nonlinear networked system. • The behavior of proposed filter in terms of its error covariance is assessed by conditional Cramér-Rao lower bound. • An upper bound of the Cramér-Rao lower bound is presented for some nonlinear networked systems. • Some necessary conditions for bounded error covariance of proposed filter are given. Abstract This technical note is concerned with particle filter for the discrete-time nonlinear networked control system. First, modified particle filter algorithm with Markovian packet dropout and time delay is proposed, and its error covariance is benchmarked by Markovian Cramér-Rao lower bound. Second, an upper bound of the Markovian Cramér-Rao lower bound is presented for some special nonlinear networked systems. Third, some necessary conditions for the boundness of error covariance are given by obtaining some sufficient conditions for the bounded Markovian Cramér-Rao lower bound. Finally, numerical examples are presented to illustrate the efficiency of proposed particle filter. [ABSTRACT FROM AUTHOR]

We consider a Lévy risk process and a Sparre-Andersen risk process with Parisian ruin in the presence of a constant dividend barrier. We demonstrate that with few exceptions, ruin occurs with probability one. Subsequently, generalizations to certain dependent risk processes are discussed. Despite the mathematical nature of this paper, its goal is to convey some simple conclusions to the actuarial community. The reader may focus solely on the introduction and conclusion sections (Sections 1 and 5, respectively) as well as the numerical illustrations. [ABSTRACT FROM AUTHOR]

This paper addresses the extremal problem of the null subcarriers based Doppler scale estimation in underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) communication. The cost function constructed of the total energy of null subcarriers through discrete Fourier transform (DFT) is proposed. The frequencies of null subcarriers are identified from non-uniform Doppler shift at each tentative scaling factor. Then it is proved that the cost function can be fitted as a quadratic polynomial near the global minimum. An accurate Doppler scale estimation is achieved by the location of the global scarifying precision and increasing the computation minimum through polynomial interpolation, without complexity. A shallow water experiment is conducted to demonstrate the performance of the proposed method. Excellent performance results are obtained in ultrawideband UWA channels with a relative bandwidth of 67%, when the transmitter and the receiver are moving at a relative speed of 5 kn, which validates the proposed method. [ABSTRACT FROM AUTHOR]

We propose a scheme to realize storage and retrieval of two-component optical soliton in a coherent atomic system. The system under consideration is a cold, lifetime-broadened four-level atomic gas with a tripod configuration working at the condition of double electromagnetically induced transparency. We show that due to the existence of two dark states, the optical absorption of the probe pulse can be largely reduced. In addition, the two orthogonal polarization components of the probe pulse with a form of vector optical soliton cannot only be slowed down substantially but also be stored and retrieved robustly by switching a control laser field off and on. We also show that it is possible to achieve a memory of N-component optical soliton by using the N dark states in a (N + l)-pod system (N > 2). The results reported here may have promise in applications for light information processing in a weak nonlinear regime. [ABSTRACT FROM AUTHOR]

Fully homomorphic encryption (FHE) allows arbitrary computation on encrypted data and thus has potential in privacy-preserving computing. However, efficiency is still the bottleneck. In this paper we present an area-efficient and highly unified reconfigurable multi-core architecture (named ReMCA) for full Residue Number System (RNS) variant of Fan-Vercauteren variant of Brakerski’s scheme (RNS-BFV), which employs a variable number of reconfigurable processing elements (PEs) and RNS channels. The PE unit can be flexibly configured as NTT, INTT or modular multiplier, thereby avoiding the need of other extra computational units. To reduce the computational complexity, ReMCA merges the pre/post-processing into NTT/INTT and unifies the read/write structure of NTT and INTT. Also, a conflict-free memory access pattern that doesn’t need separate bit-reversal operation is proposed to optimize the memory access. Furthermore, targeting different computational requirements, a unified hardware architecture mapping model and data memory organization model are introduced, and all the computing units that RNS-BFV involved are optimized and mapped on ReMCA. ReMCA is evaluated on a Xilinx Virtex-7 FPGA platform. Running at 250MHz, it can perform 2260 homomorphic multiplication per second. When normalized to the same parameter set, the throughput and Area-Time-Products (ATPs) of ReMCA achieve $1.45\times \sim 5.51\times $ and $1.58\times \sim 5.12\times $ improvements. [ABSTRACT FROM AUTHOR]

We propose a scheme to obtain stable nonlinear optical pulses and realize their storage and retrieval in an ultracold ladder-type three-level atomic gas via electromagnetically induced transparency. Based on Maxwell-Bloch equations we derive a nonlinear equation governing the evolution of the probe-field envelope and show that optical solitons with an ultraslow propagating velocity and extremely low generation power can be created in the system. Furthermore, we demonstrate that such ultraslow optical solitons can be stored and retrieved by switching a control field off and on. Due to the balance between dispersion and nonlinearity, the ultraslow optical solitons are robust during propagation, and hence their storage and retrieval are more desirable than those of linear optical pulses. This raises the possibility of realizing the storage and retrieval of light and quantum information by using solitonic pulses. [ABSTRACT FROM AUTHOR]

For intelligent transportation research, the detection of companion vehicle patterns aids in excavating behavioral relation between vehicles. This paper builds a dynamic license plate corpus based on streaming automatic number plate recognition data and combines the monitoring cameras character division to mine companion vehicle groups in real time. First, we establish the traffic flow graph based on vehicle trajectory data, and the improved PageRank algorithm is used to obtain the influence of the monitoring cameras. Second, the time-sliding window mechanism in Spark Streaming is applied to the streaming data, and the creation and updating of vehicle dynamic license plate corpus are completed according to the driving trajectory data. Finally, the plate-number dynamic graph computing algorithm is proposed to establish the dynamic relation graph between vehicles based on dynamic corpus and character identification of monitoring cameras. The camera characters are used as the influencing factor to correlate with the graph formed by vehicle nodes. The companion groups are obtained by real-time calculation of the trim and weight in the graph. Experimental analysis on the real license plate recognition dataset shows that the proposed model can effectively reduce the complexity of data processing and can detect companion vehicle groups in real time. [ABSTRACT FROM AUTHOR]

The time evolution of residual entanglement in a three-qubit system embedded in a photonic crystal is investigated by using a modified conjugate gradient method. In the isotropic photonic crystal the phenomena of entanglement "sudden death" and entanglement "sudden birth" are found due to the decoherence induced by the environment and its memory effect. Compared with the environment of an isotropic photonic crystal, entanglement has a longer lifetime in the anisotropic photonic crystal if the transition frequency is near the band edge. However, once the entanglement disappears, at a finite time in the anisotropic photonic crystal, it cannot revive, which means the phenomenon of entanglement sudden birth cannot happen in the anisotropic photonic crystal. The tripartite entanglement decays faster than bipartite entanglement in both types of photonic crystal, which indicates that multipartite entanglement is more fragile than bipartite entanglement in resisting quantum noise. [ABSTRACT FROM AUTHOR]

The article offers information on the Anti-Monopoly Law (AML) of the People's Republic of China that took effect last August 2008. According to the article, AML is a comprehensive competition code that covers the familiar kinds of antitrust content depicted in the laws of more mature antitrust jurisdictions. It notes that its effectivity provides an opportunity to examine the ways AML has developed.

Entanglement plays an important role in quantum computation and information. We can only manipulate an entangled quantum state shared among several distant parties by local operations with classical communication (LOCC). Thus, it is of great importance to characterize the conditions by which we can determine whether one pure quantum state can be transformed to another pure state by LOCC. It is well known that separable operations and LOCC are not equivalent. Dozens of results have illustrated this difference. Little do we know about this difference despite these recent results. It is shown in this paper that if the initial state |ψ〉 and final state |ϕ〉 are genuine tripartite pure states in the Greenberger-Horne-Zeilinger (GHZ) class then |ψ〉 can be transformed to |ϕ〉 by separable operations if and only if |ϕ〉 can be transformed to |ϕ〉 by deterministic LOCC. That is, SEP equals LOCC on tripartite GHZ states. [ABSTRACT FROM AUTHOR]

The article discusses international security and relates it with the U.S. president Donald Trump. Topics discussed include decision of France and Germany concerning Iranian nuclear deal, Europe's military spending, and Trump's administration expectations from Europe and its aim of a unipolar world that will be led by the U.S.

Purpose: The purpose of this paper, computational fluid dynamics (CFD) work, is to promote turbulent thermal convection in a heated circular tube using a passive scheme of a slotted twisted sheet. Design/methodology/approach: The inventive design uses square-cut and conjugate triangular perforations to diversify the twisted tape for better thermal convection. The current novel passive scheme methodology is accomplished by carving the same square cuts and slitting various sizes of equilateral triangle perforations (side length varies between 8 and 16 mm). The re-normalisation group turbulence model and the semi-implicit method for pressure-linked equation method examine the turbulent thermal convection aspects of all simulations at different Reynolds numbers (6,000, 10,000 and 14,000). Findings: The analyses of simulations exhibit that the placement of a twisted tape with triangle perforations and equidistant square cuts can effectually promote thermal convection in a circular tube. A larger-sized triangle perforation can increase the thermal convection enhancement and thermal performance factor, but an enlarged perforation may decrease the thermal convection enhancement and thermal performance factor. As a result, compared with the smooth circular tube, the circular tube with the slotted twisted sheet slit by a 10 mm equilateral triangle brings about the maximum improvement ratio of the mean Nusselt number of about 2.8 at Re = 6,000. Under weighing the friction through the circular tube, the tube with the slotted twisted sheet slit by a 10 mm equilateral triangle gains the best thermal performance factor of about 1.36 at Re = 6,000. Research limitations/implications: The working fluid is water and its physical features are assumed to be constant. In addition, the fluid is considered a steady flow in this CFD work. Practical implications: These CFD predictions will benefit the development of heat exchanger tubes equipped with a slotted twisted sheet to acquire preferable thermal convection enhancement. Social implications: Higher thermal performance achieved by placing a slotted twisted tape in a heated tube will benefit society in lower energy consumption, machinery maintenance costs and impact on the environment. Originality/value: This study combined triangle perforations and square cuts on the twisted sheet. This combination can induce the fluid flow across the sheet to disturb the swirling flow and then promote the fluid mixing to increase thermal convection. Therefore, this modified tape can be a profitable passive device for designing a heat exchanger. [ABSTRACT FROM AUTHOR]

In this Rapid Communication, we investigate the universal properties of a spin-polarized two-component Fermi gas in one dimension (1D) using the Bethe ansatz. We discuss the quantum phases and phase transitions by obtaining exact results for the equation of state, the contact, the magnetic susceptibility, and the contact susceptibility, giving a precise understanding of the 1D analog of the Bose-Einstein condensation and Bardeen-Cooper-Schrieffer crossover in three dimensions (3D) and the associated universal magnetic properties. In particular, we obtain the exact form of the magnetic susceptibility χ~1/√T exp(-Δ/T) at low temperatures, where Δ is the energy gap and T is the temperature. Moreover, we establish exact upper and lower bounds for the relation between polarization P and the contact C for both repulsive and attractive Fermi gases. Our findings emphasize the role of pair fluctuations in strongly interacting 1D fermion systems that can shed light on higher dimensions. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we are concerned with the existence and uniqueness of positive solutions for the following fractional boundary value problems given bywhere is the standard Riemann–Liouville fractional derivative, subject either to the boundary conditions or for . Our analysis relies on a fixed point theorem of a sum operator. Our results can not only guarantee the existence of a unique positive solution, but also be applied to construct an iterative scheme for approximating it. Two examples are given to illustrate the main results. [Copyright &y& Elsevier]

We introduce a scheme based on adiabatic passage that allows for long-range quantum communication through tight-binding chain with always-on interaction. By adiabatically varying the external gate voltage applied on the system, the electron can be transported from the sender's dot to the aim one. We numerically solve the Schrodinger equation for a system with a given number of quantum dots, It is shown that this scheme is a simple and efficient protocol to coherently manipulate the population transfer under suitable gate pulses. The dependence of the energy gap and the transfer time on system parameters is analyzed and shown numerically. Our method provides a guidance for future realization of adiabatic quantum State transfer in experiments. [ABSTRACT FROM AUTHOR]