Fading Zhao

Triboelectric nanogenerators (TENGs), which operate based on a combination of contact-electrification and electrostatic induction, have been widely studied as potential mechanical-energy harvesters and self-powered sensors, in which roles they have several advantages. As well as being able to harvest low-frequency mechanical energy – which is the most common type of such energy in the ambient environment – they are easy to make from a wide range of materials; low in cost; and environmentally friendly. This has led to an exponential growth in the popularity of TENGs, especially wearable ones. Hydrogels, meanwhile, are characterized by their high transparency, high stretchability, anti-freezing properties, and self-healing abilities, and have thus emerged as popular materials from which to fabricate wearable TENGs. Accordingly, this paper comprehensively reviews the literature on hydrogel-based TENGs, including work on their fundamental mechanisms; the synthesis and functionalization of the hydrogels used to fabricate them; how those hydrogels are incorporated into them; their most important properties; and their existing applications. As biomechanical sensing and mechanical energy harvesting are two of the most important potential applications for such devices, the challenges and benefits of facilitating such devices’ real-world use in these two areas are also explored. The review concludes that hydrogels are excellent materials for fabricating TENGs for potential application in wearable sensors and energy harvesters. And, as hydrogels and TENGs have already been used successfully, both separately and together, in various areas such as drug and nutrition delivery, the potential applications of hydrogel-based TENGs would appear to be nearly limitless.

Rather than using noble gas, room air is used as the working gas for an atmospheric pressure room-temperature plasma. The plasma is driven by submicrosecond pulsed directed current voltages. Several current spikes appear periodically for each voltage pulse. The first current spike has a peak value of more than 1.5 A with a pulse width of about 10 ns. Emission spectra show that besides excited OH, O, N2(C–B), and N2+(B–X) emission, excited NO, N2(B–A), H, and even N emission are also observed in the plasma, which indicates that the plasma may be more reactive than that generated by other plasma jet devices. Utilizing the room-temperature plasma, preliminary inactivation experiments show that Enterococcus faecalis can be killed with a treatment time of only several seconds.

<italic>Lactobacillus plantarum</italic>-12 can relieve colitis, and the results have some practical value in applications.

Abstract The aim of this study was to evaluate the mechanism of dielectric barrier discharge cold plasma (DBD‐CP) sterilizing function on milk and to analyze the influences of DBD‐CP on the structure and physicochemical performance of milk. It was verified that DBD‐CP sterilizing function resulted in a broken bacterial cell membrane, reduced activity of metabolic enzymes, and bacterial DNA destruction. DBD‐CP treatment would bring in some more stabilized structures obtained from scanning electron microscopy and Fourier‐transform infrared spectroscopy. The values of color, viscosity, pH, and titratable acidity showed an acceptable physicochemical property with DBD‐CP treatment at 70 V (120 s) and 80 V (120 s). Therefore, it indicated that DBD‐CP could be used as a new sterilization method for milk.

A high-efficiency inverse class-F microwave rectifier for wireless power transmission is described in this letter. The proposed inverse class-F harmonic termination network is realized by connecting a λ/12 open-ended transmission line in parallel with the diode cathode, and a λ/8 short-ended transmission line in series with the diode anode. This structure yields a compact layout, and measurement results have demonstrated a peak conversion efficiency of 80.4% for an input power of 13 dBm at 2.35 GHz, and an efficiency larger than 60% within the bandwidth 2.25-3 GHz and for a wide range of output loads.

In this article, a Schottky diode-based microwave rectifier that employs coupled transmission lines (CTLs) is proposed. CTL is herein used to enhance the voltage amplitude across the Schottky diode with the consequent increase in the rectifier efficiency, especially for low input powers. It is also shown that multiple cascaded CTLs can further enhance the rectifier conversion efficiency, even if this benefit is partially annihilated by the increased insertion loss. Several compact prototypes with single and dual CTLs for 2.45 GHz have been fabricated and measured for different input power levels. Particularly, a single CTL rectifier exhibits RF-to-dc conversion efficiency of 67.7% for an input power of 0 dBm, leading to an improvement of about 3% with respect to other referred rectifiers (with a dc load of 4.47 kQ), while dual CTL rectifier has an outstanding efficiency of 75.3% for an input power of only 5.5 dBm (with a dc load of 1.76 kQ). Passive voltage boost by means of CTLs can be applied to other rectifier circuits as also demonstrated.

Seafood provides a range of health benefits due to its nutritional and bioactive components. However, the bioactive peptides derived from Mytilus edulis proteins were seldom reported, especially their beneficial effects related to bone growth in vitro and in vivo. In this study, the water soluble protein from Mytilus edulis was isolated and the osteogenic activity of Mytilus edulis protein was determined in vivo. The protein from Mytilus edulis was subjected to simulated digestion in vitro, and the hydrolysate of different stages for osteogenic activity by osteoblast proliferation. It was found that the hydrolysate, derived from proteins hydrolyzed by pepsin for 2 h and trypsin for 3 h, showed high osteogenic activity, which induced an increase of 35.56 ± 2.92% in mouse-MC3T3-E1-preosteoblast-cell growth and the alkaline-phosphatase activity was 2.94 ± 0.10 mU, which was an increase of 19.78% compared with that of the control. Moreover, the molecular weight distribution of the peptides and the composition of the free amino acids were determined in order to evaluate the nutritional properties. These findings showed that the water soluble protein from Mytilus edulis could be used in functional food as a bioactive ingredient, which would be beneficial for bone growth and health.

A compact high-efficiency and high-power class-F microwave rectifier for the frequency of 2.45 GHz is described in this letter. The proposed rectifying circuit mainly consists of a high reverse breakdown voltage Schottky diode for high power conversion, and a novel harmonic termination circuit, resulting in a simpler and more compact structure. The microwave rectifier has been optimized with the aid of a simulation software, and the manufactured prototype exhibits a measured microwave-to-dc conversion efficiency larger than 80% for an input power level of 31 dBm, in good agreement with simulation results.

Food safety is of constant major concern worldwide. Each year, hundreds of millions of people fall ill due to consuming contaminated food, and the resulting economic loss runs into hundreds of billions of dollars. To mitigate these issues, we developed Tribo-sanitizer, which utilizes a freestanding rotational triboelectric nanogenerator (FSR-TENG) to convert mechanical energy into sustainable, low-cost or free electricity that powers an ultraviolet-C (UVC) lamp for food-safety applications. Thanks to the air gap in its circuit – a design inspired by a natural phenomenon, lightning, which can lead to electrical breakdown of air – the optimal FSR-TENG can generate a high voltage output of more than 4,000 V. This high electrical output, in turn, enables brighter illumination of the UVC lamp. Tribo-sanitizer’s decontamination efficacy was evaluated against a gram-positive bacterial strain (Listeria monocytogenes) and a gram-negative one (Escherichia coli O157:H7) inoculated in a liquid buffer, on a polymer widely used in the food-packaging industry, and on two types of fresh produce. Tribo-sanitizer achieved a 5.03-log reduction and a 5.95-log reduction for E. coli O157:H7 in buffer solution and on polyethylene terephthalate (PET), respectively, in line with the 5-log reduction recommended in government guidelines for microbial control. The log reductions for L. monocytogenes in buffer solution and on PET were 4.36 and 3.81, respectively. Lesser effectiveness was observed with the apples and romaine lettuce, likely due to these fresh produce samples’ greater surface roughness as compared to PET, one of the most widely used polymers for the construction of food packaging and drinks bottles. Our results also demonstrate that biomechanical motions can provide Tribo-sanitizer with sufficient power to achieve bacterial inactivation, demonstrating its excellent potential for use in low-resource settings. With further improvements, it could help mitigate severe food-safety problems around the world, leading to a more secure and sustainable food system.

An in-package voltage-sensing integrated magnetometer for low frequency neural recording at room temperature is presented. The detection system consists of a voltage mode CMOS amplifier with an active biasing circuit and a Metglas/Polyvinylidene fluoride (PVDF)-based magnetoelectric (ME) unimorph sensor measuring 10×3×0.025 mm in volume, representing the smallest ME sensor volume reported to date. Over the frequency range of interest (0.5 Hz–1 kHz), both theories and experiments are in excellent agreement and the fabricated magnetometer exhibits a frequency independent signal-to-noise ratio (SNR) at the system level. The magnetometer achieves a SNR of 3000 and detects a minimum detectable field of 30 nano-Tesla waveform. This system in package provides a feasibility demonstration of integration of ME sensors directly with NMOS readout electronics aimed at tiny magnetic field detection for bio-imaging applications.

The error sources of state of charge(SOC) estimation of li-ion battery based on Kalman filter is analyzed in this paper. To LiFePO4 power battery, the extremely flat part during the normal SOC range of SOC-OCV curve will require strong restriction to the voltage detection especially. This paper aims at the influence of the measuring precision of the voltage and current signal of battery management system (BMS) to SOC estimation of the li-ion battery including LiFePO4 battery. A simulation analysis is performed independently in Simulink on the assumption that other factors are under ideal conditions, in which the effects of Gaussian white noise and offset error of measurement of BMS are discussed respectively to simulate the actual vehicle condition. The principle to the precision index design of BMS is proposed according to the analysis result, in addition, a high-precision data acquisition system is developed as a precise calibration benchmark device for BMS.

This paper presents a simple and low cost solution for the implementation of a screw relaxing sensor based on ultra-high frequency (UHF) radio frequency identification (RFID) passive tags.The proposed method opportunistically uses the natural capability of a metallic screw (or a metallic part fixed on a plastic screw) to realize an electrical continuity between two electrical lines, which is exploited to realize an open/closed switch mechanism associated to the tightened/relaxed screw status.Several switch-like possible realizations are described according to different working environments and situations, as well as tag-sensor implementation schemes.Three tag-sensors are designed and manufactured to comply with metallic or non-metallic application surfaces and to work within the UHF RFID Chinese band 920.5 -924.5 MHz, showing a reliable discrimination capability between well-tightened and relaxed screw states.Finally, parameters such as maximum detection surface and minimum detection time are evaluated for completing the analysis of the presented detection system.

This manuscript deals with the design of a metamaterial-based surface structure for high efficiency wireless power harvesting or collection. Differently from the previously presented structures which require the use of thicker and low-loss (and for this reason high cost) dielectric substrates, the presented work employs a dual-layer structure with a thin low-loss material and an air gap; they allow for the design of very high absorption efficiency metamaterial-based surfaces, with noticeably reduced costs. Furthermore, the air gap thickness can be used as a new degree-of-freedom (more easily adjustable than the thickness of a single-layer structure) for the optimization of other design requirements such as bandwidth or structure sizes. In comparison with other existing designs, the proposed metasurface shows a comparable absorption efficiency of 84.4% but with a larger power collection surface and lower costs.

This letter discusses a nonlinear Schottky diode modeling method for microwave rectifier design and fast optimal diode selection. Diode power losses due to the diode series resistor, junction capacitor, built-in potential, and breakdown voltage are analyzed based on the current–voltage diode characteristic curve which can accurately predict the maximum achievable power conversion efficiency (PCE) of the rectifier circuit in both low and high input power regions. Closed-form equations are then derived to predict the PCE of a given diode at a specific working condition (input power, frequency, and load value), which can be a very useful tool for fast optimal diode selection. The proposed model has been verified both numerically and experimentally for different Schottky diodes and working frequencies, finding very good correspondence with circuit simulation results and confirming the reliability of the discussed method.

An ultrahigh-frequency (UHF) radio frequency identification (RFID) tag structure which includes both received signal demodulation and reflected signal amplification abilities for standard compatibility is described in this letter. To let demodulation and reflected signal amplification features coexist, a simple RF switch is used to separate the reception and reflection signal paths, and a reflection amplifier (RA) is connected to one of the two RF switch paths to realize the amplified reflection state. The RF switch can guarantee good impedance matching under reception/reflection conditions; moreover, by selecting it judiciously, i.e., with a low insertion loss, it is possible to simultaneously achieve high tag sensitivity and reflection amplification. Measurement on a tag prototype has revealed a maximum read range of 96 m (with a tag sensitivity of −42 dBm) and an average power consumption of 1.134 mW.

The changes of protein digestibility, the peptides in the digestive juice and angiotensin I converting enzyme (ACE) inhibitory activity after heating of oysters were investigated. The digestibility of raw oysters was 71.1%, and that of oysters heated at 100 °C was 67.9%. A total of 169 and 370 peptides were identified from the digestion of raw oysters and heated oysters, respectively. According to UPLC-Q-TOF-MS spectra, the peptides with a molecular weight below 2000 Da accounted for 87.6% of the total peptides of raw oysters and 94% of heated oysters. Testing the ACE inhibitory activity in vitro, the IC50 values of raw oyster and cooked oyster were 6.77 μg/mL and 3.34 μg/mL, respectively. Taken together, the results showed that heated oysters could produce more active peptides and provide ACE inhibitory activity.

This communication deals with the design of discrete apertures (DAs) for wireless power transfer (WPT) within the Fresnel region and provides some design guidelines to enhance WPT efficiency. In fact, although the aperture excitations optimization problem, given two specific continuous or DAs, has been already researched, the effect of antenna arrays design choices (such as the number of antenna elements or their spacings) on the WPT efficiency has not been investigated yet. In order to do that, WPT efficiency formulation has been theoretically analyzed to understand the different antenna parameters contributions to the power transfer efficiency (PTE). After that, the problem of the array excitation optimization in the sense of maximum PTE has been revisited including cases with or without perfect impedance matching. Finally, different array designs and relative achievable PTEs have been compared systematically, and it is shown that arrays with interelement spacing in the order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.3\lambda $ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.4\lambda $ </tex-math></inline-formula> (tightly coupled arrays) provide the largest PTE (also for oblique WPT cases) when the array excitation is calculated taking into account the impedance mismatching.

Power quality(PQ) monitoring is an important issue to electric utilities and many industrial power customers. This paper presents a new distributed monitoring instrument based on Digital Signal Processing (DSP) and virtual measuring technology. The instrument is composed of EOC module, Feeder Control Unit(FCU) and Supervision Unit(SU). EOC module is used to implement the data acquisition and high speed data transmission of busbar voltage; FCU performs data acquisition and processing of feeders; SU based on virtual measuring technology is used to further analyze and process power quality parameters, achieves data storage and management. Wavelet-transformation which is implemented into SU detects transient power quality disturbance, while digital filtering, windowing, the software fixed-frequency sampling method, linear interpolation and Fast Fourier Transformation(FFT) are realized by DSP. Therefore, the monitoring instrument not only implements real-time, comprehensive high-precision and management for all power quality parameters, but also helps confirm source of the disturbance, improve the quality of power supply and increase the stability performance of power system.

In this paper, a microwave rectifier based on a Schottky diode, a short-ended transmission line, and a microstrip coupled transmission line is proposed, resulting in a very simple and compact structure if compared with other similar designs. Furthermore, the proposed microwave rectifier is shown to be effective for achieving good impedance matching and, at the same time, it provides outstanding RF-to-DC conversion efficiency for input power as low as 1 mW. In particular the manufactured prototype exhibits a measured microwave-to-DC conversion efficiency of 62% which is a remarkable result if compared with state-of-the-art designs based on the same Avago HSMS285C or similar Schottky diodes.

Dominant frequency of blasting waveform attenuates with increasing propagation distance, leading to diverse diffractive effects on a roadway located in different sublevels. To investigate the roadway fracture characteristics in response to varying blasting wave frequencies and geo-stresses. Numerical simulation and experiments were performed by using discrete element methods and acoustic emission (AE) techniques, respectively. Roadway response differences in terms of microcracks propagation regions were primarily investigated, to reveal the relationships between damage-prone regions and the lateral pressure coefficient and blast waveform frequencies. The results showed that the excavation damage zone (EDZ) and the types of microcracks developed are primarily influenced by the principal stress direction. Low-frequencies blast waves contribute significantly to the overall damage to the surrounding rock around the roadway, while high-frequencies blast waves mainly damage the sides of the facing blast. Under the coupling effect of principal stress and blast wave, microcracks are more prone to generate in regions coupling with high-stress concentration regions induced by principal stress and disturbed regions diffracted by blast waves. With the results from this study, the roadway support should consider the difference in damage-prone regions triggered by blasting waves with varying dominant frequencies under different lateral pressure coefficients.

A multiple single-stage voltage multipliers in parallel is analyzed and proved theoretically to exhibit slowly changing input impedance with the wide load range in this letter. Based on this unique property, a low-power microwave rectifier consisting of two (which is the optimal number) single-stage voltage multipliers in parallel is designed, fabricated, and measured for different output load, which showed a good characteristics in both efficiency and load range, and kept power conversion efficiency (PCE) higher than 60% from 3 to 20 k <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$ </tex-math></inline-formula> , in good agreement with simulation results.

A low-voltage high-swing voltage-biased Colpitts voltage-controlled oscillator (VCO) is proposed for wireless applications. A small capacitive voltage divide factor is chosen to enhance the output swing and improve the phase noise performance. To further enhance the negative resistance, and thus decrease the start-up time, the bulk terminals of the gm-boosting transistors are dynamic-biased by the low-swing nodes provided by the inherent tapped capacitors in Colpitts VCOs. Due to the switching operation mode of the gm-boosting transistors and the absence of common-mode nodes for the switching transistors, the flicker noises up-conversion is largely suppressed. Designed in a 0.18-μm CMOS process, the postlayout simulation results show that it provides a phase noise of -127.66 dBc/Hz at 1 MHz offset centered at 3.76 GHz and a figure-of-merit (FoM) of 192.4 dBc/Hz while dissipating 4.71 mW from a 0.6 V supply. The tuning range is 17% (from 3.28 GHz to 3.89 GHz) and the 1/f <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> phase noise corner is only 60 kHz.

This paper describes a fast methodology for the optimization of antenna arrays for radiative wireless power transfer (WPT). The method is based on the maximization of the Rayleigh quotient but, instead of simulating the whole transmission/reception antenna array system, this paper proposes to exploit the single element far-field approximation to evaluate all entries of the transmission matrix, greatly reducing the required computational effort and therefore enabling the optimization of large antenna arrays. A numerical analysis is described to validate the proposed approach.

Ultrasonic partial discharge detector can discover and locate the partial discharge, and is used widely.Recently more and more ultrasonic sensor and partial discharge detector were produced by different producer.There are so many styles and kinds that detector functions are intermingled.For example, center frequency, frequency range, sensitivity are different widely, making the detect results are highly varied.So it is necessary strongly to standard the calibration technology and start application of ultrasonic partial discharge detector.The paper introduces the method and application for ultrasonic partial discharge detector calibration.

The vehicle front-end styling is a key factor for obtaining better performance of pedestrian protection.Based on the Pedestrian Protection Regulation of the European Commission(Directive 78/2009/EC) and the evaluation procedures of pedestrian protection in European New Car Assessment Program(Euro-NCAP),styling design was optimized for the front-end,including the hood,fender,ventilated cover plate,and bumper in a passenger car,using CAS(Computer-Aided Styling),in consideration of the requirements of head impact areas and leg impact areas.The results show that the optimized front-end styling effectively controls the impact areas,in favor of the pedestrian protection performance improvement,which provides practice in the styling design for new vehicles.

An intelligent control system of an electric water heater was designed,which mainly used in temperature accuracy with higher requirements for the experimental sites or industrial production environment.Nec78k0513d microcontroller was used as the core,Pt100 as temperature sensor.The circuit was simple,efficient and practical.The software used a fuzzy PID control algorithm to complete the intelligent control.The fact that the general water temperature is controlled by single method is improved by the system with fast dynamic response,high accuracy temperature and energy-saving features.

A real-time wind electrical energy quality monitoring system was designed.Based on LabVIEW and Matlab,the functions of data acquisition,analysis and processing,result show,data inquiry and abnormal condition warning were realized.The basic structure of this system and techniques for achieving system's hardware and software were introduced.The monitoring system was put into operation in a substation and favorable effect was achieved.

The pulse oximeter, a widely used noninvasive monitor of arterial oxygen saturation, has numerous applications in anesthesiology and clinic care. The calibration usually has to be made while using the oximeter to ensure the reliability of the measurement. This paper introduces a kind of pulse oxygen saturation calibrator,which can calibrate the output of oximeter exactly.