Comparative Study on Perimeter Intrusion Detection System of High-speed Railway

The perimeter intrusion detection system is critical to China’s railway safety.An efficient intrusion detection system can effectively avoid human casualties and property damage.This article makes a comprehensive comparison of popular detection systems in recent years.It first outlines the characteristics and classification of intrusion detection systems,and then introducestherelevantliteratureofcontactandnon-contactsystemsaccordingtodifferenttypes,andalsointroducesthe principles and architecture of the models they use in detail.Finally,the detection performance and suitable environment under different system models are analyzed by comparison.

Effect of temperature on heavy ion-induced single event transient on 16-nm FinFET inverter chains

The variations of single event transient(SET)pulse width of high-LET heavy ion irradiation in 16-nm-thick bulk silicon fin field-effect transistor(Fin FET)inverter chains with different driven strengths are measured at different temperatures.Three-dimensional(3D)technology computer-aided design simulations are carried out to study the SET pulse width and saturation current varying with temperature.Experimental and simulation results indicate that the increase in temperature will enhance the parasitic bipolar effect of bulk Fin FET technology,resulting in the increase of SET pulse width.On the other hand,the increase of inverter driven strength will change the layout topology,which has a complex influence on the SET temperature effects of Fin FET inverter chains.The experimental and simulation results show that the device with the strongest driven strength has the least dependence on temperature.

Location privacy protection of maritime mobile terminals

Mobile Edge Computing(MEC)can support various high-reliability and low-delay applications in Maritime Networks(MNs).However,security risks in computing task offloading exist.In this study,the location privacy leakage risk of Maritime Mobile Terminals(MMTs)is quantified during task offloading and relevant Location Privacy Protection(LPP)schemes of MMT are considered under two kinds of task offloading scenarios.In single-MMT and single-time offloading scenario,a dynamic cache and spatial cloaking-based LPP(DS-CLP)algorithm is proposed;and under the multi-MMTs and multi-time offloading scenario,a pseudonym and alterable silent period-based LPP(PA-SLP)strategy is proposed.Simulation results show that the DS-CLP can save the response time and communication cost compared with traditional algorithms while protecting the MMT location privacy.Meanwhile,extending the alterable silent period,increasing the number of MMTs in the maritime area or improving the pseudonym update probability can enhance the LPP effect of MMTs in PA-SLP.Furthermore,the study results can be effectively applied to MNs with poor communication environments and relatively insufficient computing resources.

Combined spatial-temporal energy harvesting and relay selection for cognitive wireless powered networks

In order to improve the Energy Efficiency(EE)and spectrum utilization of Cognitive Wireless Powered Networks(CWPNs),a combined spatial-temporal Energy Harvesting(EH)and relay selection scheme is proposed.In the proposed scheme,for protecting the Primary User(PU),a two-layer guard zone is set outside the PU based on the outage probability threshold of the PU.Moreover,to increase the energy of the CWPNs,the EH zone in the two-layer guard zone allows the Secondary Users(SUs)to spatially harvest energy from the Radio Frequency(RF)signals of temporally active PUs.To improve the utilization of the PU spectrum,the guard zone outside the EH zone allows for the constrained power transmission of SUs.Moreover,the relay selection transmission is designed in the transmission zone of the SU to improve the EE of the CWPNs.In addition to the EE of the CWPNs,the outage probabilities of the SU and PU are derived.The results reveal that the setting of a two-layer guard zone can effectively reduce the outage probability of the PU and improve the EE of CWPNs.Furthermore,the relay selection transmission decreases the outage probabilities of the SUs.

Using NSGA-Ⅲ for optimising biomedical ontology alignment

To support semantic inter-operability between the biomedical information systems, it is necessary to determine the correspondences between the heterogeneous biomedical concepts, which is commonly known as biomedical ontology matching. Biomedical concepts are usually complex and ambiguous, which makes matching biomedical ontologies a challenge. Since none of the similarity measures can distinguish the heterogeneous biomedical concepts in any context independently, usually several similarity measures are applied together to determine the biomedical concepts mappings. However, the ignorance of the effects brought about by different biomedical concept mapping’s preference on the similarity measures significantly reduces the alignment’s quality. In this study, a non-dominated sorting genetic algorithm (NSGA)-III-based biomedical ontology matching technique is proposed to effectively match the biomedical ontologies, which first utilises an ontology partitioning technique to transform the large-scale biomedical ontology matching problem into several ontology segment-matching problems, and then uses NSGA-III to determine the optimal alignment without tuning the aggregating weights. The experiment is conducted on the anatomy track and large biomedic ontologies track which are provided by the Ontology Alignment Evaluation Initiative (OAEI), and the comparisons with OAEI’s participants show the effectiveness of the authors’ approach.

Speech Enhancement via Mask-Mapping Based Residual Dense Network

Masking-based and spectrum mapping-based methods are the two main algorithms of speech enhancement with deep neural network(DNN).But the mapping-based methods only utilizes the phase of noisy speech,which limits the upper bound of speech enhancement performance.Maskingbased methods need to accurately estimate the masking which is still the key problem.Combining the advantages of above two types of methods,this paper proposes the speech enhancement algorithm MM-RDN(maskingmapping residual dense network)based on masking-mapping(MM)and residual dense network(RDN).Using the logarithmic power spectrogram(LPS)of consecutive frames,MM estimates the ideal ratio masking(IRM)matrix of consecutive frames.RDN can make full use of feature maps of all layers.Meanwhile,using the global residual learning to combine the shallow features and deep features,RDN obtains the global dense features from the LPS,thereby improves estimated accuracy of the IRM matrix.Simulations show that the proposed method achieves attractive speech enhancement performance in various acoustic environments.Specifically,in the untrained acoustic test with limited priors,e.g.,unmatched signal-to-noise ratio(SNR)and unmatched noise category,MM-RDN can still outperform the existing convolutional recurrent network(CRN)method in themeasures of perceptual evaluation of speech quality(PESQ)and other evaluation indexes.It indicates that the proposed algorithm is more generalized in untrained conditions.

Propagation characteristics of guided waves in a liquid filled pipe embedded in a porous medium

A model of a liquid-filled pipe embedded in a porous medium is built to research its wave propagation characteristics,and to analyze the effect of the parameters of porous media on the dispersion.The dispersion equations are established on the basis of the elastic-dynamic theory of the liquid-saturated porous solid.The characteristic of dispersion and the time domain waveform in pipes of different thicknesses and with different porous-medium parameters are discussed theoretically and numerically.Results reveal that the porosity has little impact on dispersion,and the attenuation of guided wave increases with porosity,whilst the porosity influences the displacement amplitude of the time domain waveform.It is hard to detect the permeability variation of the media by the dispersion.The drawn conclusion can provide some theoretical instruction and guidance for the nondestructive testing of buried pipe.

Propagation characteristics of low-frequency axisymmetric waves in fluid-filled pipes embedded in the viscoelastic medium

The propagation characteristics of the low-frequency axisymmetric waves in buried fluid-filled pipes are investigated theoretically,based on the Kennard thin-walled shell equations,the Helmholtz equation,and the Kelvin-Voigt linear viscoelastic model.Analytic expressions of the phase velocity are derived for both the fluid-dominated wave and the shell-compressed wave under lubricated contact,via considering the surrounding soil as a viscoelastic medium.The dispersion and attenuation curves of the two wave types are obtained and verified numerically.The ratio of the radial pipe wall displacements is analyzed,with particular emphasis on the effects of the thickness-to-radius ratio and the quality factor on the dispersion and attenuation characteristics of the fluid-dominated wave.The results show that the viscoelastic property has slight effects on the phase velocities of the two wave types,but it influences the attenuation severely.The fluid-dominated wave influences the radial pipe wall displacement significantly and is the primary carrier of leakage noise energy;its phase velocity increases as a function of the thickness-to-radius ratio while the attenuation decreases.It also shows that the dispersion and attenuation of the fluid-dominated wave decrease as a function of the quality factor.The work will provide insights and guidance for the leakage detection of buried fluid-filled pipes.

Interface wave propagation characteristics of liquid-immersed porous cylinder

This paper devotes to investigate the propagation characteristics of the interface wave on the liquid-immersed porous cylinder, and special emphasis is paid on the dependence of the dispersion relation on the porous media parameters. A model of liquid-immersed porous cylinder is established theoretically. Based on the elastic-dynamic theory of liquid-saturated porous solid and wave theory, the dispersion curves and transient response of open-pores and sealed-pores are simulated numerically, and their dependence on the cylinder radius and porous medium parameters are analyzed. The results show that the Stoneley-Scholte wave can be clearly distinguished with other waves in the time domain, and the Stoneley-Scholte wave dispersion relates intimately with the porosity of the porous medium and cylinder radius, whilst the permeability of the media has little effect on the dispersion property.

Towed line array sonar platform noise suppression based on spatial matrix filtering technology

The spatial matrix filter was designed and used for solving the problem to detect a weak target who was influenced by the strong nearby platform noise interference of the towed line array sonar. The MFP technology and the DOA estimation technology were combined together by using the sound propagation characteristics of both target and interference. The spatial matrix filter with platform noise zero response constraint was designed by the near-field platform noise normal modes copy vectors and the far-field plane wave bearing vectors together. The optimal solution of the optimization problem for designing the spatial matrix filter was deduced directly, and it was simplified by the generalized singular value decomposition. The total response error to the plane wave bearing vectors and the total response to the platform noise copy vectors were given. The phenomena that strong interferences existed in the bearing course and blind areas existed after filtering were analyzed by the correlation between the plat- form noise copy vectors and the plane wave bearing vectors. It could be found from simulations that it has less blind area and higher detection ability by using the spatial matrix filtering technology.

Second-order harmonic field characteristics at solid-solid interface with P wave incidence

The second-order harmonic field characteristics at the solid-solid interface with P wave incidence were evaluated according to the second-order potential theory.An isotropic solid-solid interface was established to solve the boundary value problem of second-order nonhomogeneous potential equation based on the Lagrange’s method of variation parameters.A numerical computation was performed to analyze the incident angle and second-order harmonic displacement.The results show that the longitudinal wave and transverse wave displacements of second-order harmonic field rapidly increase at a specific incidence angle.Moreover,the special solutions of displacement abruptly change for incident angle θw.Finally,the effect of boundary surface on second-order harmonic sound field is also discussed.