Coverage of communication-based sensor nodes deployed location and energy efficient clustering algorithm in WSN

An effective algorithm based on signal coverage of effective communication and local energy-consumption saving strategy is proposed for the application in wireless sensor networks.This algorithm consists of two sub-algorithms.One is the multi-hop partition subspaces clustering algorithm for ensuring local energybalanced consumption ascribed to the deployment from another algorithm of distributed locating deployment based on efficient communication coverage probability(DLD-ECCP).DLD-ECCP makes use of the characteristics of Markov chain and probabilistic optimization to obtain the optimum topology and number of sensor nodes.Through simulation,the relative data demonstrate the advantages of the proposed approaches on saving hardware resources and energy consumption of networks.

A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter

This paper presents an AOT-controlled(adaptive-on-time,AOT)valley-current-mode buck converter for portable application.The buck converter with synchronous rectifier not only uses valley-current-mode control but also possesses hybridmode control functions at the same time.Due to the presence of the zero-current detection circuit,the converter can switch freely between the two operating modes without the need for an external mode selection circuit,which further reduces the design difficulty and chip area.The converter for the application of high power efficiency and wide current range is used to generate the voltage of 0.6–3.0 V with a battery source of 3.3–5.0 V,while the load current range is 0.05–2 A.The circuit can work in continuous conduction mode with constant frequency in high load current range.In addition,a stable output voltage can be obtained with small voltage ripple.In pace with the load current decreases to a critical value,the converter transforms into the discontinuous conduction mode smoothly.As the switching period increases,the switching loss decreases,which can significantly improve the conversion efficiency.The proposed AOT controlled valley current mode buck converter is integrated with standard 0.18μm process and the simulation results show that the converter provides well-loaded regulations with power efficiency over 95%.When the circuit switches between the two conduction modes drastically,the response time can be controlled within 30μs.The undershoot voltage is controlled within 25 mV under a large current hopping range.

Privacy Protection Based Access Control Scheme in Cloud-Based Services

With the rapid development of computer technology, cloud-based services have become a hot topic. They not only provide users with convenience, but also bring many security issues, such as data sharing and privacy issue. In this paper, we present an access control system with privilege separation based on privacy protection(PS-ACS). In the PS-ACS scheme, we divide users into private domain(PRD) and public domain(PUD) logically. In PRD, to achieve read access permission and write access permission, we adopt the Key-Aggregate Encryption(KAE) and the Improved Attribute-based Signature(IABS) respectively. In PUD, we construct a new multi-authority ciphertext policy attribute-based encryption(CP-ABE) scheme with efficient decryption to avoid the issues of single point of failure and complicated key distribution, and design an efficient attribute revocation method for it. The analysis and simulation result show that our scheme is feasible and superior to protect users' privacy in cloud-based services.

RUAP:Random Rearrangement Block Matrix-Based Ultra-Lightweight RFID Authentication Protocol for End-Edge-Cloud Collaborative Environment

Cloud computing provides powerful processing capabilities for large-scale intelligent Internet of things(IoT)terminals.However,the massive realtime data processing requirements challenge the existing cloud computing model.The edge server is closer to the data source.The end-edge-cloud collaboration offloads the cloud computing tasks to the edge environment,which solves the shortcomings of the cloud in resource storage,computing performance,and energy consumption.IoT terminals and sensors have caused security and privacy challenges due to resource constraints and exponential growth.As the key technology of IoT,Radio-Frequency Identification(RFID)authentication protocol tremendously strengthens privacy protection and improves IoT security.However,it inevitably increases system overhead while improving security,which is a major blow to low-cost RFID tags.The existing RFID authentication protocols are difficult to balance overhead and security.This paper designs an ultra-lightweight encryption function and proposes an RFID authentication scheme based on this function for the end-edge-cloud collaborative environment.The BAN logic proof and protocol verification tools AVISPA formally verify the protocol’s security.We use VIVADO to implement the encryption function and tag’s overhead on the FPGA platform.Performance evaluation indicates that the proposed protocol balances low computing costs and high-security requirements.

High-power microwaves response characteristics of silicon and GaAs solar cells

The high-power microwave(HPM)effect heats solar cells,which is an important component of a satellite.This creates a serious reliability problem and affects the normal operation of a satellite.In this paper,the different HPM response characteristics of two kinds of solar cells are comparatively researched by simulation.The results show that there are similarities and differences in hot spot distribution and damage mechanisms between both kinds of solar cell,which are related to the amplitude of HPM.In addition,the duty cycle of repetition frequency contributes more to the temperature accumulation of the solar cells than the carrier frequency.These results will help future research of damage assessment technology,reliability enhancement and the selection of materials for solar cells.

Steady-state and transient electronic transport properties of β-(Al_(x)Ga_(1-x))_(2)O_(3)/Ga_(2)O_(3)heterostructures:An ensemble Monte Carlo simulation

The steady-state and transient electron transport properties ofβ-(Al_(x)Ga_(1-x))_(2)O_(3)/Ga_(2)O_(3)heterostructures were investigated by Monte Carlo simulation with the classic three-valley model.In particular,the electronic band structures were acquired by first-principles calculations,which could provide precise parameters for calculating the transport properties of the two-dimensional electron gas(2DEG),and the quantization effect was considered in theΓvalley with the five lowest subbands.Wave functions and energy eigenvalues were obtained by iteration of the Schrödinger–Poisson equations to calculate the 2DEG scattering rates with five main scattering mechanisms considered.The simulated low-field electron mobilities agree well with the experimental results,thus confirming the effectiveness of our models.The results show that the room temperature electron mobility of theβ-(Al_(0.188)Ga_(0.812))_(2)O_(3)/Ga_(2)O_(3)heterostructure at 10 k V·cm^(-1)is approximately153.669 cm^(2)·V^(-1)·s^(-1),and polar optical phonon scattering would have a significant impact on the mobility properties at this time.The region of negative differential mobility,overshoot of the transient electron velocity and negative diffusion coefficients are also observed when the electric field increases to the corresponding threshold value or even exceeds it.This work offers significant parameters for theβ-(Al_(x)Ga_(1-x))_(2)O_(3)/Ga_(2)O_(3)heterostructure that may benefit the design of high-performanceβ-(Al_(x)Ga_(1-x))_(2)O_(3)/Ga_(2)O_(3)heterostructure-based devices.

Optimization design of autofocusing metasurface for ultrasound wave application

In this paper,two optimized autofocusing metasurfaces(AFMs)with different desired focal distances are designed by using particle swarm optimization(PSO)algorithm.Based on the ffnite element simulation software COMSOL Multiphysics,the performance of ultrasound transducer(UT)with AFM at different design parameters in Airy distributions(r0,ω)and the bottom thickness(d)of AFM are simulated and analyzed.Based on the simulation data,the artiffcial neural network model is trained to describe the complex relationship between the design parameters of AFM and the performance parameters of UT.Then,the multiobjective optimization function for AFM is determined according to the desired performance parameters of UT,including focal position,lateral resolution,longitudinal resolution and absolute sound pressure.In order to obtain AFMs with the desired performance,PSO algorithm is adopted to optimize the design parameters of AFM according to the multiobjective optimization function,and two AFMs are optimized and fabricated.The experimental results well agree with the simulation and optimization results,and the optimized AFMs can achieve the desired performance.The fabricated AFM can be easily integrated with UT,which has great potential applications in wave ffeld modulation underwater,acoustic tweezers,biomedical imaging,industrial nondestructive testing and neural regulation.

Stacked arrangement of substrate integrated waveguide cavity-backed semicircle patches for wideband circular polarization with filtering effect

We present a novel broadband circularly polarized(CP)antenna with filtering effect for X-and Kuband satellite wireless communication.The structure comprises a driven layer(also a filtering layer)and a stacked layer(also a CP layer).The bandpass filtering response consists of two radiation nulls,which is the combined effect of a substrate integrated waveguide(SIW)cavity-backed aperture and embedded driven patch.

Secure Authentication Protocol for Mobile Payment

With the increasing popularity of fintech, i.e., financial technology, the e-commerce market has grown rapidly in the past decade, such that mobile devices enjoy unprecedented popularity and are playing an everincreasing role in e-commerce. This is especially true of mobile payments, which are attracting increasing attention.However, the occurrence of many traditional financial mishaps has exposed the challenges inherent in online authentication technology that is based on traditional modes of realizing the healthy and stable development of mobile payment. In addition, this technology ensures user account security and privacy. In this paper, we propose a Secure Mutual Authentication Protocol(SMAP) based on the Universal 2 nd Factor(U2 F) protocol for mobile payment. To guarantee reliable service, we use an asymmetric cryptosystem for achieving mutual authentication between the server and client, which can resist fake servers and forged terminals. Compared to the modes currently used, the proposed protocol strengthens the security of user account information as well as individual privacy throughout the mobile-payment transaction process. Practical application has proven the security and convenience of the proposed protocol.

A self-powered piezoelectric energy harvesting interface circuit with efficiency- enhanced P-SSHI rectifier

The key to self-powered technique is initiative to harvest energy from the surrounding environment.Harvesting energy from an ambient vibration source utilizing piezoelectrics emerged as a popular method.Efficient interface circuits become the main limitations of existing energy harvesting techniques.In this paper,an interface circuit for piezoelectric energy harvesting is presented.An active full bridge rectifier is adopted to improve the power efficiency by reducing the conduction loss on the rectifying path.A parallel synchronized switch harvesting on inductor(P-SSHI)technique is used to improve the power extraction capability from piezoelectric harvester,thereby trying to reach the theoretical maximum output power.An intermittent power management unit(IPMU)and an output capacitor-less low drop regulator(LDO)are also introduced.Active diodes(AD)instead of traditional passive ones are used to reduce the voltage loss over the rectifier,which results in a good power efficiency.The IPMU with hysteresis comparator ensures the interface circuit has a large transient output power by limiting the output voltage ranges from 2.2 to 2 V.The design is fabricated in a SMIC 0.18μm CMOS technology.Simulation results show that the flipping efficiency of the P-SSHI circuit is over 80%with an off-chip inductor value of820μH.The output power the proposed rectifier can obtain is 44.4μW,which is 6.7×improvement compared to the maximum output power of a traditional rectifier.Both the active diodes and the P-SSHI help to improve the output power of the proposed rectifier.LDO outputs a voltage of 1.8 V with the maximum 90%power efficiency.The proposed P-SSHI rectifier interface circuit can be self-powered without the need for additional power supply.

The influence of pulsed parameters on the damage of a Darlington transistor

Theoretical research on the heat accumulation effect of a Darlington transistor induced by high power microwave is conducted,and temperature variation as functions of pulse repetitive frequency(PRF)and duty cycle(DC)are studied.According to the distribution of the electronic field and the current density in the Darlington transistor,the research of the damage mechanism is carried out.The results show that for repetitive pulses with the same pulse widths and different PRFs,the value of temperature variation increases with PRF increases,and the peak temperature has almost no change when PRF is lower than 200 k Hz;while for the repetitive pulses with the same PRF and different pulse widths,the larger the pulse width is,the greater temperature variation varies.The response of the peak temperature caused by a single pulse demonstrates that there is no temperature variation when the rising time is much shorter than the falling time.In addition,the relationship between the temperature variation and the time during the rising edge time as well as that between the temperature variation and the time during the falling edge time are obtained utilizing the curve fitting method.Finally,for a certain average power,with DC increases the value of temperature variation decreases.

A high EMS daisy-chain SPI interface for battery monitor system

A high EMS current-mode SPI interface for battery monitor IC(BMIC) is presented to form a daisychain bus configuration for the cascaded BMICs and the communication between the MCU and master BMIC.Based on analog and digital mixed filtering technique,the proposed daisy-chain can avoid the isolated communication issue in electromagnetic interference environment,and reduce the extensively required I/O ports of MCU,at the same time reduce the system cost.The proposed daisy-chain interface was introduced in a 6-ch battery monitor IC which was fabricated with 0.35μ m 30 V BCD process.The measurement result shows that the presented daisy-chain SPI interface achieves better EMS performance with different EMI injection while just consuming a total operation current up to 1 m A.

60 V tolerance full symmetrical switch for battery monitor IC

For stacked battery monitoring IC high speed and high precision voltage acquisition requirements,this paper introduces a kind of symmetrical type high voltage switch circuit.This kind of switch circuit uses the voltage following structure,which eliminates the leakage path of input signals.At the same time,this circuit adopts a high speed charge pump structure,in any case the input signal voltage is higher than the supply voltage,it can fast and accurately turn on high voltage MOS devices,and convert the battery voltage to an analog to digital converter.The proposed high voltage full symmetry switch has been implemented in a 0.18 μm BCD process;simulated and measured results show that the proposed switch can always work properly regardless of the polarity of the voltage difference between the input signal ports and an input signal higher than the power supply.

A congestion-aware OE router employing fair arbitration for network-on-chip

To meet the demand for high on-chip network performance, flexible routing algorithms supplying path diversity and congestion alleviation are required. We propose a CAOE-FA router as a combination of congestionawareness and fair arbitration. Buffer occupancies from downstream neighbors are collected to indicate the congestion levels, among the candidate outputs permitted by the odd-even(OE) turn model, the lightest loaded direction is selected; fair arbitration is employed for the condition of the same congestion level to replace random selection. Experimental results show that the CAOE-FA can reduce the average packet latency by up to 22.18% and improve the network throughput by up to 68.58%, with ignorable price of hardware cost.