bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement‐based V2V radio channel analysis and modelling for bridge scenarios at 5.9 GHz
Authors: Yu Junyi , Chen Wei , Li Fang , Li Changzhen , Wang Kehao , Yang Kun , Chang Fuxing
Published: October 2019

In this study, vehicle‐to‐vehicle (V2V) radio channel measurements at 5.9 GHz were conducted on a suspension bridge and a beam bridge. Given that a different structure of the two bridges will result in different channel properties, the authors study small‐scale and large‐scale propagation characteristics for the bridge scenarios based on measurement data. By using Akaike's information criteria, the study determines optimal small‐scale fading distribution. Owing to that Ricean distribution occupies the dominant position, Ricean K‐factors in the two bridge scenarios are modelled separately and compared with each other. Afterwards, power delay profiles, Doppler power spectral densities, root‐mean‐square (RMS) delay spread and RMS Doppler spread are estimated and analysed in different cases. They employ bimodal Gaussian mixture distribution (BGMD) to model the RMS delay spreads and the RMS Doppler spreads. Fitting results of the BGMDs show good matching levels. For the large‐scale propagation characteristics, path loss model for the beam bridge scenario is proposed based on the two‐ray theory. On the other hand, path loss for the suspension bridge scenario is modelled by using an empirical function derived from WINNER II. Finally, grey relational grade–mean absolute percentage error, and RMS error criteria prove the effectiveness of the two proposed path loss models.
User fairness for RSS‐based positioning in uplink cooperative NOMA
Authors: Celik Gokhan , Celebi Hasari
Published: October 2019

Geolocation of mobile nodes with non‐orthogonal multiple access (NOMA) is a crucial process for enabling advanced location‐based services (LBSs) in 5G networks. In this study, the authors investigate the theoretical limits of received‐signal‐strength (RSS)‐based positioning for uplink cooperative NOMA under different network conditions with special emphasis on the user fairness feature. In addition, they compare the performance of the RSS‐based positioning of cooperative NOMA with that of orthogonal multiple access (OMA). The Cramer‐Rao lower bounds are derived in order to show the fundamental limits of position estimation error by taking amplify‐and‐forward and decode‐and‐forward relaying into account. The numerical results for both schemes are presented and compared considering the effects of number of relays and user equipments, different relaying on the performance of RSS positioning. The effects of power allocation on the user fairness of cooperative NOMA are also investigated. The results show that the cooperative NOMA outperforms cooperative OMA in terms of positioning. It provides high precision position accuracy and user fairness under different network conditions. Hence, the results suggest that the RSS‐based positioning for uplink cooperative NOMA is a promising technique for achieving user fairness and supporting diversified low‐cost LBSs in 5G networks.
Scheduling algorithm based on preemptive priority and hybrid data structure for cognitive radio technology with vehicular ad hoc network
Authors: Pal Raghavendra , Prakash Arun , Tripathi Rajeev , Naik Kshirasagar
Published: October 2019

There are different types of messages containing different priorities in vehicular ad hoc networks. Hence, queue rescheduling is required according to priorities of arrived messages. In this study, a data structure with less computational complexity is proposed to minimise queuing delay. Further, to maintain quality of service, preemptive priority is applied to time‐bound safety messages by transferring non‐safety messages to other bands using the concept of cognitive radio technology. The time‐bound messages are transmitted using the dedicated short‐range communication spectrum without the need for spectrum sensing by vehicles. The other messages with no deadline constraint are switched to other bands near‐dedicated short‐range communication spectrum. The results show that 6.25% improvement in packet delivery ratio of cognitive radio‐enabled preemptive priority is achieved in comparison to existing cognitive radio protocol. The delay shows a slight increment of 1.1%. The packet delivery ratio of cognitive radio‐enabled non‐preemptive priority is improved by 3.24% while the delay is improved by 3.17%. The data storage required for storing sensing data of 50 channels for 10 days is only 45 Mb.
Non‐fragile control design and state estimation for vehicle dynamics subject to input delay and actuator faults
Authors: Sakthivel Rathinasamy , Mohanapriya Saminathan , Kaviarasan Boomipalagan , Ren Yong , Anthoni Selvaraj Marshal
Published: October 2019

In this study, the authors precisely concentrate on the issue of state estimator‐based non‐fragile reliable control design of the vehicle dynamics in critical situations via the extended dissipative theory. In particular, the vehicle dynamics for rollover mitigation with input time delay and the state estimator are represented by the Takagi–Sugeno (T‐S) fuzzy model. Moreover, by constructing a suitable Lyapunov–Krasovskii functional, sufficient conditions for asymptotic stability and extended dissipativity of the proposed T‐S fuzzy control system are formulated in terms of linear matrix inequalities (LMIs) such that the estimated state values are exactly synchronised with the actual state values of the considered vehicle model. Also, a non‐fragile reliable control design method is then presented via the formulated LMI‐based conditions, which can satisfactorily prevent the vehicle rollover in critical situations. Finally, the proposed theoretical results are verified through simulations wherein the significance and importance of the designed non‐fragile controller are clearly illustrated.
Coordinated formation control of wheeled mobile robots with switching communication topologies
Authors: Wang Zhanxiu , Liu Tengfei
Published: October 2019

The coordinated formation control of wheeled mobile robots (WMRs) with directed and switching communication topologies is studied. In particular, together with the non‐holonomic constraint, physical constraints on the velocity, acceleration and angular velocity are taken into account. Through dynamic feedback linearisation, the kinematic model of each robot is transformed into a double‐integrator subject to the physical constraints. Then, coordinated controllers with successive loops are developed for the formation control. The problem caused by the physical constraints is solved by introducing saturations to the control loops. It is proved that each controlled WMR admits an invariant set property, and the formation control objective is achievable as long as a mild joint connectivity condition is satisfied by the communication topology.
Algebraic approaches for the design of simultaneous observers for linear systems
Authors: Menini Laura , Possieri Corrado , Tornambe Antonio
Published: October 2019

In this study, algebraic techniques are proposed to design observers capable of estimating the state of multiple linear continuous‐time systems. In order to pursue this objective, first an algebraic technique is given to compute the set of all the linear inverses of the observability map of a single plant. Such a result is then used to characterise, through algebraic geometry tools, the simultaneous observability of multiple linear systems both in the forced and in the autonomous case. Such a characterisation is finally employed to design a single observer that is capable of estimating the state of multiple linear systems.
Multi‐parametric iterative algorithms for discrete periodic Lyapunov matrix equations
Authors: Wu Ai‐Guo , Zhang Wen‐Xue , Zhang Ying
Published: October 2019

Two multi‐parametric iterative algorithms are developed to solve the forward discrete periodic Lyapunov matrix equation associated with discrete‐time linear periodic systems. An important feature of one of the proposed algorithms is that the information in the current and the last steps is used to update the iterative sequence. Necessary and sufficient conditions for these two algorithms to be convergent are provided in terms of the roots of a set of polynomial equations. Based on these conditions, a two‐dimensional section method is established to search suboptimal tuning parameters for these two algorithms. In addition, convergence properties are also analysed for some special cases of the obtained algorithms. Finally, numerical examples are provided to illustrate the effectiveness of the proposed algorithms. It can be found that the presented algorithms have better convergence performance than some existing iterative algorithms by choosing proper tuning parameters.
Output tracking control of strict‐feedback non‐linear systems under asymmetrically bilateral and time‐varying full‐state constraints
Authors: Sun Yawen , Gao Shigen , Ning Lingbin , Dong Hairong , Ning Bin
Published: October 2019

The state feedback output tracking control problem is investigated for a class of uncertain non‐linear strict‐feedback system subject to asymmetrically bilateral and time‐varying full‐state constraints. Non‐linear mapping is employed to deal with full‐state constraints and the system is transformed into an uncertain pure‐feedback system. For the transformed system, an approximation‐free backstepping control scheme is proposed by using performance function rather than employing any estimator. It is shown that the proposed control strategy can guarantee that all signals in the closed‐loop system are bounded and the tracking errors can be made arbitrarily small by choosing proper control gains. Meanwhile, the states are set within the asymmetrically bilateral and time‐varying full‐state constraints. At last, two simulation examples are obtained to demonstrate the feasibility and effectiveness of the proposed control algorithm wherein the practical system for metro is considered.
Design and characterisation of advanced magnetic material‐based core for isolated power converters used in wave energy generation systems
Authors: Islam Md. Rabiul , Farrok Omar , Rahman Md. Ashib , Kiran Mahbubur Rahman , Muttaqi Kashem M. , Sutanto Danny
Published: October 2019

The oceanic wave energy generation has been drawn significant attention in the field of power engineering recently. These generation systems are basically direct drive electrical power generators connected to the wave energy devices with the variable frequency drives (VFDs). This study proposes an application of high‐frequency transformers at the output stages of VFDs for the galvanic isolation purpose among multiple output ports of VFDs in a wave farm. The design process of a high‐frequency magnetic link involves multiphysics problems that entail complex tradeoffs between electrical and magnetic properties including efficiency. Moreover, the performance of the magnetic link depends on the switching characteristics of the power switching devices and various excitation signals. Therefore, extensive multiphysics research in the field of design and optimisation of magnetic links is needed to develop next‐generation technologies. In this study, a finite‐element method‐based systematic process is presented for the design of amorphous alloy‐based core of the high‐frequency magnetic link. Two cores are developed and characterised in the laboratory. The characterised data obtained from the experiment can be used in the future design optimisation of other high‐frequency magnetic links.
Market model for clustered microgrids optimisation including distribution network operations
Authors: Batool Munira , Islam Syed , Shahnia Farhad
Published: October 2019

This paper proposes a market model for the purpose of optimisation of clustered but sparse microgrids (MGs). The MGs are connected with the market by distribution networks for the sake of energy balance and to overcome emergency situations. The developed market structure enables the integration of virtual power plants (VPPs) in energy requirement of MGs. The MGs, internal service providers (ISPs), VPPs and distribution network operator (DNO) are present as distinct entities with individual objective of minimum operational cost. Each MG is assumed to be present with a commitment to service its own loads prior to export. Thus an optimisation problem is formulated with the core objective of minimum cost of operation, reduced network loss and least DNO charges. The formulated problem is solved by using heuristic optimization technique of Genetic Algorithm. Case studies are carried out on a distribution system with multiple MGs, ISP and VPPs which illustrates the effectiveness of the proposed market optimisation strategy. The key objective of the proposed market model is to coordinate the operation of MGs with the requirements of the market with the help of the DNO, without decreasing the economic efficiency for the MGs nor the distribution network.
Coordinated design of PSS and unified power flow controller using the combination of CWT and Prony methods with the help of SPEA II multi‐objective optimisation algorithm
Authors: Naghshbandy Ali Hesami , Faraji Ayda
Published: October 2019

Since the initial objective of power system stabiliser (PSS) units and flexible AC transmission system (FACTS) devices is the damping of inter‐area and local oscillations, it is very substantial that the network electromechanical oscillatory modes are identified for tuning the controller of large‐scale interconnected power systems. In this research, a method based on the combination of continuous wavelet transform and Prony algorithm is presented to study low‐frequency electromechanical oscillations of the power system. The coordinated design of PSS and FACTS parameters become a multi‐objective optimisation problem that will be solved using the SPEA II. The residue method is used to improve damping and satisfy the controller constraints of the suggested power systems. Finally, the proposed method of mode estimation and controller design is simulated on the two well‐known test case systems, namely IEEE 2‐area 4‐generator and New England‐New York 68‐bus 16‐generator systems using MATLAB software. The results represent accurate performance and validity of the proposed method to improve oscillation damping, dynamic stability of the power systems.
Reliability assessment of integrated energy system considering the uncertainty of natural gas pipeline network system
Authors: Yang Hejun , Zhang Yeyu , Ma Yinghao , Zhang Dabo , Sun Lei , Xia Shiwei
Published: October 2019

Natural gas, as a clean fossil energy, has been widely used in power generation system by converting chemical energy into electrical energy through gas turbines. However, the natural gas pipeline network system (NGPNS) is comprised of many equipments, and the failure of any equipment will probably cause the outage of gas turbines. Therefore, this study proposes an analytical method which can incorporate the uncertainty of NGPNS into the reliability assessment of integrated energy system. Firstly, on the basis of an analytical technique, NGPNS's operating states and the corresponding state probabilities are simulated. Secondly, a state transferring and equivalence technique is proposed for transferring the unreliability of NGPNS to the involved outage of gas turbines. Thirdly, an equivalent reliability model of gas turbine is established for taking into account the uncertainty of NGPNS. Finally, the NGPNS is connected to the Roy Billinton Test System through the coupling of gas turbines between electrical and gas networks. The results of case studies verify the correctness and effectiveness of the proposed algorithm.
Binary tomography on the isometric tessellation involving pixel shape orientation
Authors: Nagy Benedek , Lukić Tibor
Published: October 2019

In this study, a tomography reconstruction problem of binary images is considered on the isometric grid. On this grid, the triangle pixels have two types of orientations, accordingly, the authors call them delta or nabla shape pixels. The proposed reconstruction method uses data of projections of three natural directions. They are the lane directions of the triangular tessellation (these directions are somewhat analogous to row/column directions on the rectangular grids). The projection ray, penetrating through a grid lane, now not passing through the middle of pixels (i.e. through the middle line of triangle shape pixels), as usually taken, but little bit shifted from the middle parallel to the lane. This method provides the exact information about the number of nabla and delta shape triangle pixels in each lane of the image. This additional information is included in the reconstruction process to improve the quality of reconstruction. They formulate the suggested model into an energy‐minimisation problem and apply a gradient‐based approach for its minimisation. They show and analyse various experimental results on test images. The presented approach shows both better quality reconstructions and shorter running time than the earlier approaches.
Efficient data handover and intelligent information assessment in software‐defined vehicular social networks
Authors: Sohail Muhammad , Wang Liangmin , Ali Rashid , Rahim Sajjad , Yao Jiaying
Published: October 2019

Emerging trends in future Intelligent Transportation System allow vehicles to have on‐board sensors and digital computers, which might help in real‐time information exchange among neighbour vehicles. However, considering infected sensors, computer malfunctioning, and selfishness, legitimate vehicles might inject untrustworthy information into the network. In this situation, to find the credibility of disseminated information in less time delay is the key agenda. To provide a better solution and seamless interconnectivity among vehicles, the authors have proposed software‐defined vehicular social networks (VSN). The proposed scheme takes advantage of social connections among vehicles, which are created and maintained over software‐defined networking (SDN) cloud. The choice of using SDN cloud is due to its open flow nature, as the devices are more programmable and can be used to optimise the network operation. SDN based on these social connections is able to efficiently handover relevant data from truster to trustee vehicle. The closeness of the relationship between two vehicles in these VSN is modelled and assessed with TrustWalker algorithm by applying novel three‐valued subjective logic operations. In the end, to validate the proposed scheme, packet loss and delay are considered as important network evaluation metrics. Performance analysis is done under different schemes and simulation results support the proposed scheme in terms of execution time.
Efficiency‐based approach to quantifying ‘tuneability’ performance in frequency‐agile narrowband antennas
Authors: James Oliver , Hilton Geoff , Beach Mark
Published: October 2019

Many communications systems require reconfigurable band access in compact form factors. Contemporary literature routinely reports ‘tuneability’ (or frequency agility) in input response terms (S11), yet repeatable efficiency data were reported in <40% of cases surveyed. Despite the low efficiencies associated with many tuneable narrowband antennas, e.g. electrically small antennas (ESAs), reference methods to quantify tuneability in terms of a tuned range of realised antenna efficiency, average efficiency in the band and integrated efficiency–bandwidth product do not exist and thus have not been widely adopted. Here, these metrics have been formulated for general application to efficiency‐based tuneability assessment of narrowband antennas. Application to a set of fixed‐frequency/varactor‐tuned ESAs (ka = 0.19–0.31) in the ultra‐high frequency band is demonstrated. Tuning range of 10% or 25% realised efficiency was found to be several times narrower than S11 < −6 dB tuning range for antennas in this study and in the literature, highlighting the need for a shift to efficiency‐based tuneability reporting in support of RF system design analysis. The integrated efficiency–bandwidth product has been demonstrated for combined efficiency and reconfigurability comparison of tuneable antennas, providing a platform for future performance grading of a diverse range of antenna tuning technologies.
Tunable balanced bandpass filter with constant absolute bandwidth and high common mode suppression
Authors: Song Kaijun , Wang Xi , Fan Maoyu , Chen Yuxuan , Patience Shema Richard , Iman Abdelqani Mohamed , Fan Yong
Published: October 2019

A reconfigurable balanced bandpass filter with constant absolute bandwidth (ABW) and high common‐mode (CM) suppression by using the interdigital coupling compensation circuit structure is presented here. The odd‐ and even‐mode equivalent circuits of the presented balanced bandpass filter are presented and analysed. The differential mode and CM signals are misaligned by the half‐wavelength resonators, which are coupled by interdigital coupling circuit to improve the coupling coefficient and decrease the circuit dimension. Changing the voltage of the four varactors, which are placed at two ends of the half‐wavelength resonators with interdigital coupling circuits, can tune the coupling coefficient and resonant frequency at the same time. A tunable balanced bandpass filter with ABW is designed and realised. The measured results indicate that the differential‐mode tuning centre frequency range extends from 0.97 to 1.72 GHz, the 3 dB ABW is 80 ± 5 MHz, and the CM suppression is >30 dB in the differential‐mode operating passband. Experimental results are in good agreement with the theoretical and simulated ones.
Zero‐bias elimination with selective non‐commensurate sampling for PN code tracking
Authors: Ma Chunjiang , Ni Shaojie , Tang Xiaomei , Xiao Zhibin , Sun Guangfu
Published: October 2019

Zero bias is the main source of error in high‐precision applications based on pseudo‐noise (PN) ranging. This study proposes a selective non‐commensurate sampling frequency design method applied to the digital code‐tracking loop which can effectively suppress the code‐phase zero bias caused by incomplete sampling of the spread spectrum signal. The maximum (MAX) and standard deviation (STD) of the zero bias independent of code and the initial phase are used to design the sampling frequency. The code correlation reference waveform is utilised to establish a statistical analysis model of the digital discriminator zero bias. Analytical expressions of the zero‐bias MAX and STD are derived. The performance of the proposed method is assessed as per code Doppler, binary offset modulation, and thermal noise. Fibre optic time synchronisation equipment is used to determine the feasibility of eliminating PN code‐tracking zero bias based on selective non‐commensurate sampling.
New rotation vector algorithm based on a high‐order polynomial
Authors: Guo Xiaole , Liu Xixiang , Yan Jie , Wang Yixiao , Zeng Jichao , Pan Shuguo
Published: October 2019

To effectively compensate the non‐commutativity error existing in attitude computation, a new rotation vector algorithm is presented in this study. In order to calculate the rotation vector, a high‐order polynomial which accurately describes the angular motion of carrier is introduced. By this algorithm, it is easy to increase the attitude computation accuracy without the need for increasing the output frequency of the gyro. The algorithm's performance is compared with classical multi‐sample algorithm and optimal coning algorithm in the context of coning motion. Simulation results demonstrate that the new algorithm outperforms optimal coning algorithm in high dynamic environment and classical multi‐sample algorithm in low dynamic environment (by 2–3 and 1–2 orders, respectively).
Research on influence of special‐shaped honeycomb radar absorbing structure for wide‐band absorbing design
Authors: Ming‐liang Wang , Jia‐qi Liu , Xin Liu , Xin‐ying Zhao , Sheng‐jun Zhang , Lei Mu , Xia Ai , Guo‐bin Wan , Wei‐dong Wang , Ju‐yan Zhao
Published: October 2019

To realise wide‐band stealth of radar absorbing material, a special‐shaped honeycomb radar absorbing structure within nested cone‐shaped scattering configuration is designed. Based on the HS theory and the impedance matching design, the rule about the influence of the geometry parameter and electromagnetic parameter on the absorbing performance is analysed. In addition, the reflectivity performance is analysed on the condition of oblique incidence angles. By optimising the geometry parameters of the special‐shaped honeycomb structure and designing the multilayer composite structure based on impedance matching theory, the results indicate that the two absorbing peaks can be formed for the special‐shaped honeycomb radar absorbing structure, and the reflectivity is improved for both the vertical and oblique incidence angles.
Research on modelling and calculation method of river ice electromagnetic scattering
Authors: Huang Pingping , Shi Qiang , Tan Weixian , Xu Wei , Hu Chufeng
Published: October 2019

In order to verify the feasibility of using microwave to study Yellow River ice, the reflected power of pure ice and mixed ice is measured by electromagnetic waves of different polarisations and frequencies in the microwave chamber. The measured data of microwave chamber measurement was processed to obtain radar cross section values. Based on the experiments in the microwave chamber, this study presents a reflection model for calculating the reflection of pure ice. The calculated value obtained by the model is consistent with the measured values, which also proves the validity of the model. The results of this study will provide some basis for the follow‐up study of retrieval Yellow River ice thickness.
Fast high‐resolution imaging method for wide‐band rotating targets
Authors: Xiang Hu , Li Shaodong , Xiang Long , Chen Wenfeng , Yang Jun
Published: October 2019

To reduce the computation burden of inverse synthetic aperture radar on rotating targets imaging, a fast distributed simultaneous multiple orthogonal matching pursuit method is proposed in this study. In the proposed method, the distributed matching sparse representation model of the rotating targets is firstly established. Also then the total number of iterations is reduced by using multi‐atom recognition strategy. Simultaneously, the computational complexity of each iteration is also reduced through QR decomposition. High‐resolution image of the rotating targets can thus be obtained efficiently. Theoretical analysis and simulation results verify the effectiveness of the proposed method.
Detection of stationary humans using time‐division UWB MIMO through‐wall radar
Authors: Xinxin Sun , Liangnian Jin , Qinghua Liu
Published: October 2019

Existing radars for stationary human detection need to process echo data from all channels simultaneously, which requires the radar system with high performance. Another limitation of existing technology is poor positioning due to sidelobe interference. Here, a time‐division ultra‐wideband multiple‐input multiple‐output (MIMO) radar is presented for stationary human detection using the incoherence of respiratory echoes. Based on the delay‐and‐summation imaging method, the maximum coherence factor (MCF) is weighted to suppress sidelobe, band‐pass incoherence factor is weighted to distinguish stationary objects and human targets, and the variance factor is weighted to achieve accurate positioning. Experimental results show that this method can effectively suppress the noise, filter off the echo of the stationary object, and provide the distance and azimuth information of hidden human targets accurately.
Spectral‐factorisation Root‐MUSIC algorithm for super‐resolution ISAR imaging
Authors: Liu Qiuchen , Wang Yong
Published: October 2019

Inverse synthetic aperture radar (ISAR) is widely used in both military and civil fields recently. The fast Fourier transformation is the conventional method to obtain high‐resolution ISAR images, but it is Rayleigh limited and has high sidelobes. Root‐MUSIC served as a super‐resolution method can break the Rayleigh limit. Whereas Root‐MUSIC has computational redundancy as its roots are presented as conjugated pairs. Here, a spectral factorisation Root‐MUSIC (SF‐Root‐MUSIC) is proposed for super‐resolution ISAR imaging. SF‐Root‐MUSIC efficiently reduces the order of rooting‐polynomial of Root‐MUSIC into half and has a similar resolution ability as Root‐MUSIC. The computational complexity of SF‐Root‐MUSIC is significantly reduced compared to Root‐MUSIC. Simulated signal, MIG‐25 data, and real measured Yak‐42 data are employed to validate the validity of the proposal.
Experimental research of drone monitoring using multi‐static passive radar
Authors: Lü Min , Yi Jianxin , Wan Xianrong , Liu Yuqi
Published: October 2019

The rapid development of the drone poses potential dangers and challenges for air traffic safety. The reliable monitoring of the drones has attracted much attention around the world in recent years. This study investigates the feasibility and practicability of the multi‐static passive radar (MPR) system for the drone monitoring. The authors conduct a series of drone‐monitoring experiments using a digital‐television‐based MPR system developed in Wuhan University. The typical experimental results of the drone detection and tracking are discussed in this study in detail. The agreement is achieved between the experimental results and the ground truth from the global position system of the drones. It demonstrates advantages and prospects of the drone monitoring by the MPR system.
Insect wing‐beat frequency automatic extraction and experimental verification with a Ku‐band insect radar system
Authors: Zhang Tianran , Liu XiangRong , Hu Cheng , Wang Rui , Liu Changjiang , Li Wenqing
Published: October 2019

The wing‐beat frequency is one of the most important behavioural parameters of migratory insects and is widely used to distinguish insect species due to the diversity of wing‐beat frequency among different species. Traditional insect radar has been able to achieve automatic extraction of the wing‐beat frequency. However, its low‐range resolution and fixed threshold detection may cause false alarms and reduce the precision of wing‐beat frequency. The authors’ Ku‐band insect radar system enables high‐resolution, full‐polarised detection of insects, but has not achieved automatic extraction of wing‐beat frequency yet. The authors propose an insect wing‐beat frequency automatic extraction algorithm based on a Ku‐band insect radar system. The algorithm adopts the constant false alarm rate detector and tracks the association algorithm to get target echo automatically and combines the amplitude spectrum method and the phase spectrum method to achieve wing‐beat frequency extraction. The authors carried out the outfield experiment using the radar system and used the collected data to test the proposed algorithm. The experiment results confirm that the algorithm can extract the wing‐beat frequency of insects automatically based on the Ku‐band insect radar system, which can improve system efficiency.
Sparse‐Bayesian‐learning‐based translational motion estimation of electromagnetic vortex imaging
Authors: Li Rui , Ma Zhi‐qiang , Zhang Qun , Luo Ying , Liang Bi‐shuai , Li Guang‐ming
Published: October 2019

The electromagnetic (EM) vortex imaging has been found to have a great potential application prospect in the imaging radar field. However, current studies focus on the motionless target, which seriously limits its application in practice. Therefore, to achieve EM vortex imaging for the motion target, this study proposes a parametric sparse representation model for EM vortex imaging that takes into account a translational motion target and uses the stepped frequency signal. An iterative algorithm is developed based on the sparse Bayesian learning (SBL) algorithm to estimate the velocity, and accomplish the EM vortex imaging exploiting SBL algorithm. Simulation results demonstrate that the proposed algorithm can improve velocity estimate accuracy in terms of relative error and achieve EM vortex imaging for the motion target.
Sea‐surface floating small target detection based on feature compression
Authors: Guo Zixun , Shui Penglang
Published: October 2019

Owing to characteristics of sea clutter and diversity of floating small targets, it is significant to extract features to jointly detect targets. Due to the complexity of detectors in high‐dimensional (HD) space, feature compression is an important procedure in the design of detector. Besides, considering that the capacities of detecting target about extracted features are varied with different datasets, feature selection is supposed to be an effective method. Here, it is found that building a feature‐compression matrix can realise that mapping the feature vectors in HD space into low‐dimensional space, where the matrix is built efficiently by using the results of feature selection. Whereas information about targets which is used in building feature‐compression matrix is unknown, a training sample generator which can emulate the fundamental state of targets to help to build a feature‐compression matrix is proposed. Finally, a one‐class classifier about the feature vector which has been compressed is provided with using a new 3D convexhull learning algorithm. The experiment results on the IPIX datasets show that the proposed detector attains better detection performance than several existing detectors.
Rotation error analysis on slant 45° dual polarisation radar feature extraction
Authors: Zhang Liang , Wang Yanhua , Li Yang
Published: October 2019

Polarisation is an inner property of electromagnetic wave. It has considerable significance to analyse the polarimetric feature of targets in target recognition and classification applications. Slant 45° dual polarisation measurement is widely used due to its low requirements on system complexity and data rate on the one hand, and good polarisation measure and anti‐interference capabilities on the other. However, its performance is seriously affected by rotation angle of the polarisations in transmission and reception. Here, the impact of rotation error of the transmit–receive polarisations on feature extraction is assessed by theoretical derivation at first. The variations with rotation angles of the transmit–receive polarisations are then simulated using standard scatterers and ground targets data. This permits quantification of the resulting rotation error on slant 45° dual polarisation measurement. The impact of the rotation error on H /α and polarimetric similarity features is also quantified in results. Some practical advices on system design, calibration, and feature application are given at last.
Radio frequency interference suppression filters design for HF radar based on SOCP
Authors: Wang Zhaoyi , Shi Shengnan , He Zishu , Hu Jinfeng
Published: October 2019

High‐frequency radar is easily affected by radio frequency interference (RFI) since it shares the band with many radio services. To mitigate the RFIs, this study designs receiver for radar's fast‐time processing. Two optimisation problems are, respectively, proposed, both involving an objective function accounting for maximising the signal‐to‐interference plus noise ratio, but are distinguished with different constrains for sidelobes control. Furthermore, the authors show that the two proposed problems both can be reformulated as the second‐order cone programming, hence some well‐established interior point methods can be introduced to resolve them. Simulation results show that the designed filters can precisely control the sidelobe level from different perspectives, with the RFIs suppressed to achievable greatest extent.
Polarised HRRP scattering centre estimation via atomic norm minimisation
Authors: Liu Haibo , Xi Ying , Wang Yanhua , Li Yang , Zhao Tong
Published: October 2019

The combination of polarisation and high‐resolution technology is a promising research direction for radar automatic target recognition. Fusing the polarisation information into the scattering centre model is able to refine the scattering structural information. This study proposes a fully‐polarised radar high range resolution profile (HRRP) scattering centre estimation method based on a multiple measurement vector atomic norm minimisation model. The estimation is performed in a continuous domain, thus avoids the basis mismatch problem. The experimental results demonstrate the superiorities of the proposed method in terms of accuracy and robustness.
Edge estimation method for non‐uniform envelope pulse based on instantaneous frequency
Authors: Sun Jingyun , Xu Jiacen , Ren Lixiang
Published: October 2019

Pulse edge estimation has always been an important issue in the field of electronic reconnaissance. Here, for the unknown received pulse with non‐uniform envelope, a novel pulse edge estimation method based on instantaneous frequency is proposed. By using sliding window detection for the standard deviation of segmented instantaneous frequency of the received signal, the pulse edge rough estimation can be obtained. Then, double threshold detection on the smoothed signal segment is performed to obtain the accurate pulse edge estimation. Moreover, the parameter setting and application of this method are analysed. The simulation results show that this method can obtain the accurate estimation of the edge of unknown pulse with non‐uniform envelope, and the robustness and low computational burden of the proposed method are also demonstrated.
Dual‐station radar‐based living body detection and localisation
Authors: Yan Chao , Jia Yong , Guo Yong , Zhong Xiaoling
Published: October 2019

In this study, a dual‐station radar signal processing algorithm based on vital signal correlation is presented to deal with the problem of detection and localisation of living body with low echo power in the multi‐target scenario. The algorithm is mainly divided into the following steps. First, a cross‐correlation operation is performed on the echo signal matrices, respectively, received by two radars at different positions to obtain the correlation matrix. Then constant false alarm rate processing is used to detect the targets and extract the distance of every target relative to the two radars. Finally, the position of the target is calculated by the triangulation algorithm to achieve the localisation of living bodies. The simulation result of MATLAB software shows that this algorithm can effectively detect and locate multiple targets with different echo intensities.
Experimental verification of an integrated radar communication system
Authors: Li Zengliang , Liu Jie , Yin Ning , Wang Youcheng
Published: October 2019

With the development of modern weapon techniques, radio frequency integrated technology has attracted widespread attention as a key technology to improve the informationalised level of missiles. Radar and communication are two typical electronic types of equipment, and their integration can support and promote the development of radio frequency integrated technology. In this study, experimental verification of an integrated radar–communication system is carried out. Firstly, the key technologies to achieve radar–communication integration are theoretically analysed. The solutions of the key issues, including signal separation, time synchronisation and frequency synchronisation, are proposed. Furthermore, a radar–communication demo is implemented and the experimental verification is carried out here to verify the feasibility of the proposed methods.
Patterning of thick electroplated CoPt magnets using SU‐8 micromoulds
Authors: Wang Yuzheng , Bowrothu Renuka , Yoon Yong‐Kyu , Arnold David P.
Published: October 2019

Recently, electroplated cobalt platinum (CoPt) magnetic films have been developed that afford thick (up to ∼100 μm), high‐energy‐density (up to ∼100 kJ/m3) permanent‐magnet microstructures. However, the aggressive electroplating conditions have shown to be incompatible with most thick‐film photoresist mould materials, making patterning these films an unanswered technical challenge. In this work, it is reported a complete process flow of fabricating and removing SU‐8 photoresist moulds to enable the ultra‐thick patterned CoPt magnets on silicon wafers. The implementation of thick SU‐8 2050 electroplating moulds makes it feasible to deposit 100 µm thick CoPt magnets in 4 h. A 25 nm thick sputtered titanium layer is used as a sacrificial layer to completely release the SU‐8 mould in hydrofluoric acid after electrodeposition. Compared to prior research, significantly improved pattern definition and constant magnetic performance are observed and characterised by optical profilometer, scanning electron microscope, and vibrating sample magnetometer.
Design and analysis of novel tri‐active layer channel amorphous‐IGZO thin‐film transistor
Authors: Dargar Shashi K. , Srivastava Viranjay M.
Published: October 2019

Among high‐field mobility materials, amorphous indium–gallium–zinc oxide (In–Ga–ZnO) (α‐IGZO) has been prominent for their use in thin‐film transistors (TFTs). In this Letter, the authors present a novel structure of TFT with tri‐active layer (TAL) channel consisting of α‐IGZO and In–SnO (ITO) materials. Further, the simulation‐based analysis of the proposed device and characteristics in comparison to the single and double active layer channel structures have been reported. This work also analyses the effect of front–back channel thickness‐ratios in double‐active layer channel TFTs. The proposed TAL channel TFT describes improved switching parameters such as lower threshold voltage (VTH) − 4.24 V, high field‐effect mobility (µFE) 38.4 cm2/V‐s, moderate subthreshold swing 0.398 mV/decade, and reasonably high ON‐to‐OFF current ratio (ION/IOFF) 0.18 × 1012. The electrical characteristics persuade the significance of the proposed structure in next‐generation flat‐panel displays.
Waveguide integrated GaN distributed Bragg reflector cavity using low‐cost nanolithography
Authors: Jia Simeng , Boulbar Emmanuel D. Le , Balram Krishna C. , Pugh Jon R. , Wang Tao , Allsopp Duncan W.E. , Shields Philip A. , Cryan Martin J.
Published: October 2019

This work presents the design, fabrication and measurement of gallium nitride (GaN) distributed Bragg reflector cavities integrated with input and output grating couplers. The devices are fabricated using a new, low‐cost nanolithography technique: displacement Talbot lithography combined with direct laser writing lithography. The finite‐difference time‐domain method has been used to design all the components and measured and modelled results show good agreement. Such devices have applications in GaN integrated photonics and biosensing.
Modified carbon black/nylon 6 fibres with excellent antistatic and mechanical properties
Authors: Xin Zhang , Shanshan Yin , Yang Meng , Jian Han , Juanjuan Su
Published: October 2019

Nylon 6 (PA6) fibre has many advantages such as high strength, wear resistance, light weight, and good elasticity. However, PA6 fibre is prone to deformation in use and the antistatic ability is poor. In this Letter, the dispersion of carbon black (CB) was improved by physical methods and then added to the nylon 6 (PA6). The authors had studied that the dispersion of modified and unmodified CB in PA6 fibres with excellent mechanical properties and electrical conductivity. The results of Zeta potential and particle size test showed that the size of the CB particle modified was decreased and the absolute value of Zeta potential on the surface was increased. The results of scanning electron microscopy showed that the CB had a good dispersion in PA6; the results of thermogravimetric and Fourier transform infrared analysis showed that polystyrene sodium sulphonate was successfully coated on the surface of CB; when 5% modified CB was added in PA6 fibres, the mechanical properties of PA6 were hold up well. Interestingly, when 5% CB modified was added in PA6 fibres, the resistance of CB modified/PA6 fibre with excellent mechanical properties was reached up to 4.89 × 1011 Ω.
Evanescent wave ammonia sensor: influence of nanocrystalline TiO2 on V2O5 and MoO3
Authors: Chandrasekar Paramasivam , Subashini Thangaraj , Renganathan Balusamy , Prakash Thanigainathan
Published: October 2019

Clad‐modified fibre optic ammonia sensor was developed subsequently using pure V2O5, MoO3, and its composites with TiO2. Prior to the sensing measurement, the composite was synthesised and studied for the structural and microstructural properties using powder X‐ray diffractometer and field emission scanning electron microscope. The analysis confirms the existence of nanocrystalline anatase phase TiO2 in the grain boundaries of microcrystalline V2O5/MoO3 in the composites. Ammonia sensing measurement was performed for different concentrations of ammonia exposures up to 500 ppm. The obtained response was applied to calculate the sensitivity and it was found to be superior for the clad modified with composite material as compared to the pure microcrystalline samples are discussed in detail.
Preparation of GCE modified with ZnO@CoFe2O4 magnetic nanoparticles and its application in electrocatalytic determination of Acetaminophen
Authors: Asadpour‐Zeynali Karim , Lotfi Nasrin
Published: October 2019

In this work, a nanocomposite of zinc oxide (ZnO) and cobalt ferrite (CoFe2O4) was synthesised with a facile preparation method in order to fabricate a nanosensor for acetaminophen (AC) sensing. The ZnO nanoparticles were electrochemically deposited onto glassy carbon electrode (GCE) coated with magnetic nanoparticles CoFe2O4. The morphology and structure of ZnO@CoFe2O4 nanocomposite were investigated by scanning electron microscopy and energy dispersive X‐ray. The performance of the proposed sensor was characterised with cyclic voltammetry and differential pulse‐voltammetry techniques. The ZnO@CoFe2O4/GCE nanosensor shows excellent electrocatalytic activity for AC oxidation in phosphate buffer (pH = 7) solution and it exhibits a good linear relationship and the low limit of detection (LOD). The ZnO@CoFe2O4/GCE showed good sensitivity, selectivity, stability, reproducibility, larger specific area and fast response in comparison with other reported sensors. The result calibration diagram of using the differential pulse‐voltammetric technique has two linear ranges of 0.495–9.53 and 9.53–47.00 µm, and the LOD for AC by this method obtained 0.36 µm. The performance of this modified electrode was evaluated for measuring AC in some pharmaceutical formulations.
2D non-LTE modelling of a filament observed in the Hα line with the DST/IBIS spectropolarimeter
Authors: Schwartz P. , Gunár S. , Jenkins J. M. , Long D. M. , Heinzel P. , Choudhary D. P.
Published: October 2019

Context. We study a fragment of a large quiescent filament observed on May 29, 2017 by the Interferometric BIdimensional Spectropolarimeter (IBIS) mounted at the Dunn Solar Telescope. We focus on its quiescent stage prior to its eruption.

Aims. We analyse the spectral observations obtained in the Hα line to derive the thermodynamic properties of the plasma of the observed fragment of the filament.

Methods. We used a 2D filament model employing radiative transfer computations under conditions that depart from the local thermodynamic equilibrium. We employed a forward modelling technique in which we used the 2D model to produce synthetic Hα line profiles that we compared with the observations. We then found the set of model input parameters, which produces synthetic spectra with the best agreement with observations.

Results. Our analysis shows that one part of the observed fragment of the filament is cooler, denser, and more dynamic than its other part that is hotter, less dense, and more quiescent. The derived temperatures in the first part range from 6000 K to 10 000 K and in the latter part from 11 000 K to 14 000 K. The gas pressure is 0.2–0.4 dyn cm−2 in the first part and around 0.15 dyn cm−2 in the latter part. The more dynamic nature of the first part is characterised by the line-of-sight velocities with absolute values of 6–7 km s−1 and microturbulent velocities of 8–9 km s−1. On the other hand, the latter part exhibits line-of-sight velocities with absolute values 0–2.5 km s−1 and microturbulent velocities of 4–6 km s−1.