Resource Allocation for IRS Assistedmm Wave Wireless Powered Sensor Networks with User Cooperation

In this paper,we investigate IRS-aided user cooperation(UC)scheme in millimeter wave(mmWave)wirelesspowered sensor networks(WPSN),where two single-antenna users are wireless powered in the wireless energy transfer(WET)phase first and then cooperatively transmit information to a hybrid access point(AP)in the wireless information transmission(WIT)phase,following which the IRS is deployed to enhance the system performance of theWET andWIT.We maximized the weighted sum-rate problem by jointly optimizing the transmit time slots,power allocations,and the phase shifts of the IRS.Due to the non-convexity of the original problem,a semidefinite programming relaxation-based approach is proposed to convert the formulated problem to a convex optimization framework,which can obtain the optimal global solution.Simulation results demonstrate that the weighted sum throughput of the proposed UC scheme outperforms the non-UC scheme whether equipped with IRS or not.

Stackelberg Game for Wireless Powered and Backscattering Enabled Sensor Networks

This paper investigates a wireless powered and backscattering enabled sensor network based on the non-linear energy harvesting model, where the power beacon(PB) delivers energy signals to wireless sensors to enable their passive backscattering and active transmission to the access point(AP). We propose an efficient time scheduling scheme for network performance enhancement, based on which each sensor can always harvest energy from the PB over the entire block except its time slots allocated for passive and active information delivery. Considering the PB and wireless sensors are from two selfish service providers, we use the Stackelberg game to model the energy interaction among them. To address the non-convexity of the leader-level problem, we propose to decompose the original problem into two subproblems and solve them iteratively in an alternating manner. Specifically, the successive convex approximation, semi-definite relaxation(SDR) and variable substitution techniques are applied to find a nearoptimal solution. To evaluate the performance loss caused by the interaction between two providers, we further investigate the social welfare maximization problem. Numerical results demonstrate that compared to the benchmark schemes, the proposed scheme can achieve up to 35.4% and 38.7% utility gain for the leader and the follower, respectively.

Low Cost,Low Power Magnetic IEDs Detection Method Using Biaxial Magnetometry Digital Sensors

The magnetic improvised explosive devices （IEDs）, also commonly known as a type of a sticky bomb, is simply constructed devices yet very lethal. This paper puts forward the idea of an electronic compass that is capable of sensing the change of a magnetic field generated by a magnet and translating it into interpretable data, which could act as the base for the further studies and assist in developing a greener automated system for detecting this device. The electronic compass is specifically chosen for reducing power consumption of systems in addition to the fact that it is available at a low cost.

Calculation of Skin Depths and Eddy-Current Power Losses for Magnetic Position Sensors

We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current excitation, induces secondary currents and fields between magnetic material and magnetic position sensor. In this paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar. The analytical model is derived from basic field and circuit theory considering a linear approximation for a nonlinear permeability. Thus the skin depths and eddy-current power losses from the model in eddy-current modeling techniques at various frequencies of an excited current source can be calculated. The proposed configuration is capable of predicting the skin depths and eddy-current power losses for a magnetic position sensor and has a consistence with experiments.

Single Band EBG Antenna for Wireless Power Transfer Applications

This work demonstrates the design of a single band Electromagnetic Band Gap(EBG)antenna by employing an open stub EBG microstrip of a patch antenna for better achievements in terms of its performance to be utilized in a reconfigurable harvester to operate over a wide input power range.The EBG antenna has been used to gather RF energy and a FET-transistor has been obtain-able to determine and control the powerflow with the intention to operate at the same time for a different level of input power.The measured data of the EBG antenna shows a directivity of 8.52 dBi,a gain of 7.18 dBi,a return loss of-27 dB with a radiation efficiency of 84.3%,showing a clear enhancement in directivity,peak realized gain,and radiation efficiency by 41.76%,25.61%,and 17.12%respectively compared with a regular reference antenna;without utilized the EBG structure.Moreover,the harvester design accomplishes 40%of RF-DC power conversion efficiency over a wide dynamic input power range from-15 to 27 dBm,and its peak is around 78%.The harvester is designed to work at the ISM band for 915 MHz and is suitable for Wireless Power Transfer(WPT)uses.

Amplitude modulation measurement of symmetrical microwave power sensor

In order to reduce the mismatch error, a direct current （DC） calibration method is introduced when the modulated microwave signal is measured. The microwave power is input to the left section of the power sensor, and the DC power is input to the right of the power sensor. Due to the existence of parasitic loss and electromagnetic coupling, the microwave power results in a mismatch error. However, the DC power does not have the mismatch error. So the DC power applied in the right section can calibrate the mismatch error of the microwave power in the left section. The calibration factor is measured at different modulation rates and modulation depths.The measurement results show that the carrier frequency is the major factor influencing the measurement results. After calibration, the carrier frequency and the modulation rate have little effect on the output voltage. The frequency response becomes relatively flat in the frequency range up to 20 GHz, and the sensitivity on average is enhanced by about 0.12 mV/dBm. Therefore, the DC calibration method has a certain reference value for the terminal-type microwave power sensor.

Performance analysis of an improved dynamic power management model in wireless sensor node

The energy consumption in the wireless sensor networks is a very critical issue which attracts immediate attention for the sake of the growing demand of the billion dollar market in future. The Dynamic Power Management （DPM） technique is a way of controlling and saving the energy usage in a sensor node. Previously, researchers have proposed lifetime improving stochastic models for wireless sensor networks and limited work has been done focusing on the wireless sensor node. This paper proposes an analyser based Semi-Markov model for DPM in the event-driven sensor node. The power consumption comparison with previously proposed models without this analyser shows the analyser significant contributes to lifetime improvement. The improved model is more power efficient, presents how the DPM model observes the input event arrival and power states of the sensor node components, and then dynamically manages the power consumption of the overall system. Further, to observe the effect of event arrival, missed events, waiting time, processor utilization on the power consumption and lifetime, the proposed DPM system with the single server queuing model is developed.

Application of the thermoelectric MEMS microwave power sensor in a power radiation monitoring system

A power radiation monitoring system based on thermoelectric MEMS microwave power sensors is studied. This monitoring system consists of three modules： a data acquisition module, a data processing and display module, and a data sharing module. It can detect the power radiation in the environment and the date information can be processed and shared. The measured results show that the thermoelectric MEMS microwave power sensor and the power radiation monitoring system both have a relatively good linearity. The sensitivity of the thermoelectric MEMS microwave power sensor is about 0.101 mV/mW, and the sensitivity of the monitoring system is about 0.038 V/mW. The voltage gain of the monitoring system is about 380 times, which is relatively consistent with the theoretical value. In addition, the low-frequency and low-power module in the monitoring system is adopted in order to reduce the electromagnetic pollution and the power consumption, and this work will extend the application of the thermoelectric MEMS microwave power sensor in more areas.

Road surface condition sensor based on scanning detection of backward power

A method of detecting dry, icy and wet road surface conditions based on scanniag detection of single wavelength backward power is proposed in this letter. The detector is used to receive the backward scattered power which changes with the incidence angle. The relationship between backward power and incidence angle is used to find out the effective angle range and distinguish method. Experiment and simulation show that it is feasible to classifv these three conditions within incidence angle of 5.3 degree.

A capacitive membrane MEMS microwave power sensor in the X-band based on GaAs MMIC technology

This paper presents the modeling, fabrication, and measurement of a capacitive membrane MEMS microwave power sensor. The sensor measures microwave power coupled from coplanar waveguide （CPW） transmission lines by a MEMS membrane and then converts it into a DC voltage output by using thermopiles. Since the fabrication process is fully compatible with the GaAs monolithic microwave integrated circuit （MMIC） process, this sensor could be conveniently embedded into MMIC. From the measured DC voltage output and S-parameters, the average sensitivity in the X-band is 225.43μV/mW, while the reflection loss is below -14 dB. The MEMS microwave power sensor has good linearity with a voltage standing wave ration of less than 1.513 in the whole X-band. In addition, the measurements using amplitude modulation signals prove that the modulation index directly influences the output DC voltage.

A novel symmetrical microwave power sensor based on MEMS technology

A novel symmetrical microwave power sensor based on MEMS technology is presented. In this power sensor, the left section inputs the microwave power, while the fight section inputs the DC power. Because of its symmetrical structure, this power sensor provides more accurate microwave power measurement capability without mismatch uncertainty and temperature drift. The loss caused by the microwave signal is simulated in this power sensor. This power sensor is designed and fabricated using GaAs MMIC technology. And it is measured in the frequency range up to 20 GHz with an input power in the 0-80 mW range. Over the 80 mW dynamic range, the sensitivity can achieve about 0.2 mV/mW. The difference between the input power in the two sections is below 0.1% for an equal output voltage. In short, the key aspect of this power sensor is that the microwave power measurement is replaced with a DC power measurement.

A micromachined inline type microwave power sensor with working state transfer switches

A wideband 8-12 GHz inline type microwave power sensor, which has both working and non-working states, is presented. The power sensor measures the microwave power coupled from a CPW line by a MEMS membrane. In order to reduce microwave losses during the non-working state, a new structure of working state transfer switches is proposed to realize the two working states. The fabrication of the power sensor with two working states is compatible with the GaAs MMIC （monolithic microwave integrated circuit） process. The experimental results show that the power sensor has an insertion loss of 0.18 dB during the non-working state and 0.24 dB during the working state at a frequency of 10 GHz. This means that no microwave power has been coupled from the CPW line during the non-working state.

CMOS vision sensor with fully digital image process integrated into low power 1/8-inch chip

A digital still camera image processing system on a chip, different from the video camera system, is pre- sented for mobile phone to reduce the power consumption and size. A new color interpolation algorithm is proposed to enhance the image quality. The system can also process fixed patten noise （FPN） reduction, color correction, gamma correction, RGB/YUV space transfer, etc. The chip is controlled by sensor regis- ters by inter-integrated circuit （I2C） interface. The voltage for both the front-end analog and the pad cir- cuits is 2.8 V, and the volatge for the image signal processing is 1.8 V. The chip running under the external 13.5-MHz clock has a video data rate of 30 frames/s and the measured power dissipation is about 75 roW.

Advances in organic thermoelectric materials and devices for smart applications

Organic thermoelectric(OTE)materials have been considered to be promising candidates for large area and low‐cost wearable devices owing to their tailorable molecular structure,intrinsic flexibility,and prominent solution processability.More importantly,OTE materials offer direct energy conversion from the human body,solid‐state cooling at low electric consumption,and diversified functions.Herein,we summarize recent developments of OTE materials and devices for smart applications.We first review the fundamentals of OTE materials from the viewpoint of thermoelectric performance,mechanical properties and bionic functions.Second,we describe OTE devices in flexible generators,photothermoelectric detectors,self‐powered sensors,and ultra‐thin cooling elements.Finally,we present the challenges and perspectives on OTE materials as well as devices in wearable electronics and fascinating applications in the Internet of Things.

A novel SOI pressure sensor for high temperature application

The silicon on insulator（SOI） high temperature pressure sensor is a novel pressure sensor with highperformance and high-quality. A structure of a SOI high-temperature pressure sensor is presented in this paper.The key factors including doping concentration and power are analyzed. The process of the sensor is designed with the critical process parameters set appropriately. The test result at room temperature and high temperature shows that nonlinear error below is 0.1%, and hysteresis is less than 0.5%. High temperature measuring results show that the sensor can be used for from room temperature to 350℃ in harsh environments. It offers a reference for the development of high temperature piezoresistive pressure sensors.