Electromagnetic Wave Sensor Research Articles

Measurement and analysis of void fraction in horizontal plug flow based on electromagnetic wave sensor

Void fraction measurement is a crucial challenge in two-phase flow, which is related to the measurement of phase flow and the calculation of pressure drop. In this study, a coaxial line phase sensor is designed for void fraction acquisition and the void fraction of the plug measured has a well time-domain and Probability Density Functions (PDF) distribution characteristics. Four typical correlations were selected to compare with the measured values of the sensors, the mean absolute errors (MAPE) are 19.88 %, 18.94 %, 18.25 %, and 17.19 %, respectively. Considering the nonlinear and strong coupling between the flow characteristic parameters and the void fraction, the flow parameters were analyzed and selected by Pearson correlation coefficient. The Kernel ridge regression methods were employed to select effective variables for model training, and the Extreme gradient boosting (XGboost) machine learning model was proposed. The prediction accuracy of the model is 1.65 % (current data) and 4.18 % (literature data), respectively.

Research Progress of Human–Computer Interaction Technology Based on Gesture Recognition

Gesture recognition, as a core technology of human–computer interaction, has broad application prospects and brings new technical possibilities for smart homes, medical care, sports training, and other fields. Compared with the traditional human–computer interaction models based on PC use with keyboards and mice, gesture recognition-based human–computer interaction modes can transmit information more naturally, flexibly, and intuitively, which has become a research hotspot in the field of human–computer interaction in recent years. This paper described the current status of gesture recognition technology, summarized the principles and development history of electromagnetic wave sensor recognition, stress sensor recognition, electromyographic sensor recognition, and visual sensor recognition, and summarized the improvement of this technology by researchers in recent years through the direction of sensor structure, selection of characteristic signals, the algorithm of signal processing, etc. By sorting out and comparing the typical cases of the four implementations, the advantages and disadvantages of each implementation and the application scenarios were discussed from the two aspects of dataset size and accuracy. Based on the abovementioned discussion, the problems and challenges of current gesture recognition technology were discussed in terms of the biocompatibility of sensor structures, wearability and adaptability, stability, robustness, and crossover of signal acquisition and analysis algorithms, and the future development directions in this field were proposed.

Broadband plasmon-induced transparency to an anapole mode induced absorption conversion Janus metastructure by a waveguide structure in the terahertz region.

A Janus metastructure (MS) assisted by a waveguide structure (WGS) resting on anapole modes and exhibiting direction-dependent behavior has been developed in the terahertz (THz) region. Ultra-broadband absorption is formed by the destructive interference through the anapole as well as Janus trait and is shaped by nested WGS. In this design, vanadium dioxide (VO2) is expected to attain functional transformation from plasmon-induced transparency (PIT) to absorption. The insulating nature of the VO2 results in the creation of the PIT, which is characterized by a wide and high transmission window ranging from 1.944 THz to 2.284 THz, corresponding to the relative bandwidth of 7.4% above 0.9. However, when the VO2 reaches the metallic state, a high absorptivity of 0.921 at 2.154 THz can be implemented in the -z-direction owing to the excitement of the toroidal dipole and electric dipole moments in the near-infrared region. And in the +z-direction, the broadband absorption above 0.9 in the 1.448-2.497 THz range takes shape in virtue of surface plasmon polariton modes, in which intensely localized oscillation of free electrons is confined to the metal-dielectric interface supported by the WGS. Noting that the MS is equipped with a favorable sensitivity to the incidence angle, we develop an ultra-broadband backward absorption in the TM mode from 0.7-10 THz nearly all above 0.9 when the incidence angle changes from 30°-70°. Moreover, owing to the highly symmetrical structure, the MS exhibits exotic polarization angular stability. All the awesome properties make this MS a good candidate for various applications such as in electromagnetic wave steering, spectral analysis, and sensors.

Electromagnetic Wave Sensors for Noninvasive Blood Glucose Monitoring: Review and Recent Developments

Electromagnetic Wave Sensors for Noninvasive Blood Glucose Monitoring: Review and Recent Developments

Electrostatically Induced Voltage Generated in Two Ungrounded Metal Cases When Charged Object Moves Away from the Cases

Static electricity is used in numerous practical applications, such as copy machines and dust collectors. When a person gets up from a chair or walks in a room using an air conditioner, the person's body becomes charged. When a charged body approaches or moves away from the metal case of an electronic device, the electronic device suffurs a malfunction or failure due to the electrostatically induced voltage. The electrostatically induced voltage of a charged body moving away from a metal case is higher than the voltage induced when the charged body approaches the metal case. We conducted an experimental study on the electrostatically induced voltage generated in two ungrounded metal cases when a charged body moves away from the metal cases. The results showed that electrostatically induced voltages of 0.4 to 0.5 times was generated in the two ungrounded metal cases against the voltage of the charged body when each electrostatic induction electrode with a spark gap and each electromagnetic wave sensor is used of a noncontact electrostatic measuring device. We believe that these results will aid in the prevention of malfunction or failure of electronic devices.

Narrowband and wideband EMW path loss in underwater wireless sensor network

PurposeUtilization of electromagnetic wave (EMW) sensors in an underwater environment has the potential to increase the data rate compared to acoustic-based sensors because of the ability to use larger signal bandwidth. Nevertheless, EMW signals has the drawback of large signal attenuation in underwater, attributed to the high relative permittivity and conductivity of water compared to the atmosphere, hence employment of wide signal bandwidth is necessary to balance the data rate-attenuation trade-off. The purpose of this paper is to analyze the characteristics of both narrowband and wideband EMW signal propagation underwater and devise a path loss model for both cases.Design/methodology/approachPath loss measurement was conducted using a point-to-point configuration in a laboratory water tank while transmitting narrowband and wideband signals between a pair of wideband underwater antennas. The wideband underwater antennas use buffer-layer structures as the impedance matching layer to optimize the antenna performance when operating underwater. The path loss for narrowband signal was modeled using a multi-layer propagation equation in lossy medium considering losses at the medium boundaries. For the case of the wideband signal, a modified version of the model introducing power integration over bandwidth is adopted. These models were formulated through numerical simulations and verified by measurements.FindingsThe measured narrowband path loss marked an 80 dB attenuation using 800 MHz at 2 m distance. The proposed narrowband model agrees well with the measurements, with approximately 3 dB modeling error. Utilization of the proposed wideband path loss model resulted in a reduction of the gradient of the path loss curve compared to the case of the narrowband signal. The measured wideband path loss at 2 m distance underwater was approximately −65 dB, which has been shown to enable a working signal-to-noise ratio of 15 dB. This proves the potential of realizing high data rate transmission using the wideband signal.Originality/valueThe paper proposed a wideband propagation model for an underwater EMW sensor network, using power integration over bandwidth. The effectiveness of using wideband EMW signals in reducing path loss is highlighted, which is seldom discussed in the literature. This result will be of useful reference for using wideband signals in designing a high data rate transmission system in underwater wireless sensor networks, for example, in link budget, performance estimation and parameter design of suitable transmission scheme.

Electrostatically Induced Voltage in Metal Box When Charged Object Like Hand Moves Away From the Box to Three Directions

When a charged human body stands up from a chair or walks in a room using an air conditioner, a malfunction or failure of electronic devices is caused occasionally by the static electricity. When the charged human body operates the electronic device by a charged hand, an instantaneous electrostatically high induced voltage is generated in the metal case of the electronic device. Such the induced voltage is generated in a metal case when a charged object of charged hand moves near the metal case. An experiment is conducted where an induced voltage is measured using a real experimental setup when a charged object moves away from the metal case to the left, right, or back. The voltage induced in the metal case is measured using a spark gap and an electromagnetic wave sensor. The results show that the voltages induced in the metal case are -0.6 times the voltage of a charged object when the charged object moves away from the metal case. The induced voltage of 6 kV is generated in the metal case for the charged hand of -10 kV. The results will be beneficial in solving the malfunction or failure of electronic devices caused by induced voltages.

One pot facile transformation of CO2 to an unusual 3-D nano-scaffold morphology of carbon

An electrosynthesis is presented to transform CO2 into an unusual nano and micron dimensioned morphology of carbon, termed Carbon Nano-Scaffold (CNS) with wide a range of high surface area graphene potential usages including batteries, supercapacitors, compression devices, electromagnetic wave shielding and sensors. Current CNS value is over $323 per milligram. The morphology consists of a series of asymmetric 20 to 100 nm thick flat multilayer graphene platelets 2 to 20 µm long orthogonally oriented in a 3D neoplasticism-like geometry, and appears distinct from the honeycomb, foam, or balsa wood cell structures previously attributed to carbon scaffolds. The CNS synthesis splits CO2 by electrolysis in molten carbonate and has a carbon negative footprint. It is observed that transition metal nucleated, high yield growth of carbon nanotubes (CNTs) is inhibited in electrolytes containing over 50 wt% of sodium or 30 wt% of potassium carbonate, or at electrolysis temperatures less than 700 °C. Here, it is found that a lower temperature of synthesis, lower concentrations of lithium carbonate, and higher current density promotes CNS growth while suppressing CNT growth. Electrolyte conditions of 50 wt% sodium carbonate relative to lithium carbonate at an electrolysis temperature of 670 °C produced over 80% of the CNS desired product at 85% faradaic efficiency with a Muntz brass cathode and an Inconel anode.

Experimental realization of electromagnetic toroidal excitation for microwave applications

An experimental realization of resonant toroidal dipole excitation in the microwave regime is presented in this paper. The metasurface proposed herewith is an asymmetric double split-ring resonator exhibiting Fano-like resonance profile. One could observe that cascading the metasurface results in near-field transverse and longitudinal coupling creating dual-band toroidal moments on the structure. This planar scheme will simulate the development of enhanced light–matter interaction, electromagnetic wave slowdown and sensor design. Here we report the experimental realization of the phenomenon in the S-band frequencies, and the results are verified using multipole scattering analysis.

Real-Time Monitoring of Tetraselmis suecica in A Saline Environment as Means of Early Water Pollution Detection.

Biological water pollution, including organic pollutants and their possible transportation, via biofouling and ballast water, has the potential to cause severe economic and health impacts on society and environment. Current water pollution monitoring methods are limited by transportation of samples to the laboratory for analysis, which could take weeks. There is an urgent need for a water quality monitoring technique that generates real-time data. The study aims to assess the feasibility of three sensing techniques to detect and monitor the concentrations of the model species Tetraselmis suecica in real-time using eleven samples for each method. Results showed UV-Vis spectrophotometer detected increasing concentration of Tetraselmis suecica with R2 = 0.9627 and R2 = 0.9672, at 450 nm and 650 nm wavelengths, respectively. Secondly, low-frequency capacitance measurements showed a linear relationship with increasing concentration of Tetraselmis suecica at 150 Hz (R2 = 0.8463) and 180 Hz (R2 = 0.8391). Finally, a planar electromagnetic wave sensor measuring the reflected power S11 amplitude detected increasing cell density at 4 GHz (R2 = 0.8019).

Measurement of electrostatically induced voltages in two metal boxes using spark gaps and electromagnetic wave sensors

Electrostatically induced voltages are generated in metal boxes when a charged human body moves near boxes that have openings. The induced voltages occasionally cause malfunction and failure of electronic equipment. When a human body walks in office that uses air conditioner, the body is electrified. Hence, when a charged body, such as charged human body, moves near metal boxes, high induced voltages are generated in them. In the experiments, two metal boxes similar to the boxes of electronic equipment are used. The induced voltages generated in the two metal boxes are measured. The results will help to resolve electrostatic problem.

Silicon-Based Hybrid Integrated Photonic Chip for K ${}_{u}$ band Electromagnetic Wave Sensing

In this paper, we experimentally demonstrate a highly sensitive on-chip photonic electromagnetic wave sensor operating at 14.1 GHz with a 3 dB bandwidth of 4.84 GHz. The demonstrated electromagnetic sensor has several important advantages over conventional electrical electromagnetic sensors, including high sensitivity, compact in size, and strong immunity to electromagnetic interference. The sensor is comprised of a bowtie antenna and an asymmetric Mach-Zehnder interferometer (MZI). One arm of the MZI is an electro-optic polymer infiltrated one-dimensional slot photonic crystal waveguide (SPCW) and the other is a strip waveguide with teeth of subwavelength pitch. Bowtie antennas are designed and optimized to effectively collect 14.1 GHz microwave signal and applies it across the SPCW. The phase of the light guided in the SPCW therefore changes, and so does the amplitude of the output end of the MZI. The sensor is only 4.6 mm × 4.8 mm in size and has a low insertion loss of ~10 dB. Experimental results show the limit of detection at 14.1 GHz is 4.31 mW/m 2 , which is corresponding to a minimum detectable electric field of 1.8 V/m.

Comparison of Electromagnetic Wave Sensors with Optical and Low-frequency Spectroscopy Methods for Real-time Monitoring of Lead Concentrations in Mine Water

The feasibility of using novel electromagnetic wave sensors for real-time monitoring of metal pollution in water was assessed. Five solutions with different concentrations of lead (0, 1, 10, 50, 100 mg/L) were measured using several sensing methods: UV–Vis spectroscopy, low frequency capacitance and resistance measurements, and two sensing systems based on microwave technology. With this last approach, two sensing devices were used: a resonant cavity and a planar sensor with gold interdigitated electrode design printed on a PTFE substrate with a protective PCB lacquer coating. Results confirmed the ability of these systems to quantify the lead concentration as changes in spectrum signal at specific frequencies of the electromagnetic spectrum. Spectra were unique, with clearly observed shifts in the resonant frequencies of the sensors when placed in direct contact with different lead solutions, demonstrating the possibility of continuous monitoring with great sensitivity, selectivity, and high spatial and temporal resolution. Consequently, determination of trace and toxic metals using microwave spectroscopy is a promising alternative to traditional grab-sampling and laboratory based analyses. On-line and continuous monitoring of real-time metal concentrations offers the potential for a more effective emergency response and the platform for better scientific understanding and remediation of contaminated mine drainage.

Noninvasive <italic>In-Situ</italic> Measurement of Blood Lactate Using Microwave Sensors

This paper reports a novel electromagnetic sensor technique for real-time noninvasive monitoring of blood lactate in human subjects. The technique was demonstrated on 34 participants who undertook a cycling regime, with rest period before and after, to produce a rising and falling lactate response curve. Sensors attached to the arm and legs of participants gathered spectral data, blood samples were measured using a Lactate Pro V2; temperature and heart rate data was also collected. Pointwise mutual information and neural networks are used to produce a predictive model. The model shows a good correlation between the standard invasive and novel noninvasive electromagnetic wave based blood lactate measurements, with an error of 13.4% in the range of 0-12 mmol/L. The work demonstrates that electromagnetic wave sensors are capable of determining blood lactate level without the need for invasive blood sampling. Measurement of blood metabolites, such as blood lactate, in real-time and noninvasively in hospital environments will reduce the risk of infection, increase the frequency of measurement and ensure timely intervention only when necessary. In sports, such tools will enhance training of athletes, and enable more effecting training regimes to be prescribed.

RF 센서와 INS을 이용한 UUV 위치 추정

In this paper, we propose an underwater localization scheme through the fusion of an inertial navigation system (INS) and the received signal strength (RSS) of electromagnetic (EM) wave sensors to guarantee precise localization performance with high sampling rates. In this localization scheme, the INS predicts the pose of the unmanned underwater vehicle (UUV) by dead reckoning at every step, and the RF sensors corrects the UUV position functions using the Earth-fixed reference when the UUV is located in underwater wireless sensor networks (UWSN). The localization scheme and state modeling were conducted in the extended Kalman filter framework, and UUV localization experiments were conducted in a basin environment. The scheme achieved reliable localization accuracy during long-term navigation, demonstrating the feasibility of exploiting EM wave attenuation as Earth-fixed reference sensors.

Electrostatically induced voltage on conductive objects contained in metal box when charged body moves away from the box

Electrostatically induced voltage generated on printed circuit boards in a grounded metal box occasionally causes a malfunction and failure of the electronic equipment. A person who walks into a room that has an air conditioner can be electrified up to −10 kV or more. However, a microelectronics device malfunctions by an occurrence of induced voltage of less than 10 V. In the present paper, the induced voltages on an ungrounded one of two conductors that are contained in the metal box are measured and calculated when a charged body moves away from a partially opened metal box. The induced voltages are measured by the use of a spark gap and an electromagnetic wave sensor and are compared with the results from an electrostatic voltmeter. The induced voltages are calculated, moreover, by the use of q=cv, with the capacitances and charges. The results show that the induced voltages of −42% of the voltages of the charged body are generated in the metal box when a charged body moves away from the metal box. The results will be helpful in considering preventive measures of the malfunction and failure of electronic equipment.

Invited: Non-invasive sensing of livestock health parameters

Development of the livestock sector at EU and global level is challenging as it puts pressure on the environment as well as animal welfare. Livestock production accounts for over 40% of the overall EU agricultural output – in 2011 EU-27 farmers raised livestock with a total value of €154 billion . Products derived particularly from beef cattle, dairy cattle and small ruminants (i.e. sheep and goats) typically require farmers to graze their animals on grasslands to provide the necessary nutrition for sustainable productivity. For farmers to maintain sustainable livestock production, they must ensure that both livestock and their grazing environments are well managed. This is by no means a trivial task given that animals may be spread over large areas depending on the grazing system employed and geographical location, in addition to a farmer potentially owning many hundreds of animals. Currently farmers have no means to, remotely and in real-time, determine the location, condition and activity of their livestock and control (e.g. movement) of animals is still largely a manual process. The authors are seeking to address all of these issues through the development of a smart integrated sensor system; this paper focuses on one aspect of this system, namely the determination of animal health. A non-invasive electromagnetic wave sensor has been developed for in-situ determination of blood lactate concentration in dairy cows as a rapid indicator health status. It has been tested currently in the laboratory environment, and has been shown to deliver sensitivity to < 1 mmol-1 changes in lactate level over a range of concentrations (0-64 mmol-1) in defibrininated bovine blood through approx. 15mm of cow hide. The further development of this work will undoubtedly bring a step-change in the welfare of livestock across the sector, in addition to helping farmers maintain sustainable output to meet ever increasing pressures to produce.

Flexible electromagnetic wave sensor operating at GHz frequencies for instantaneous concentration measurements of NaCl, KCl, MnCl2 and CuCl solutions*

A novel electromagnetic wave sensor operating at GHz frequencies for real-time chlorides concentration analysis is reported. The sensor response to deionized water, NaCl, KCl, MnCl2 and CuCl solutions at various concentrations was tested. The sensing element, in the form of a silver pattern antenna that emits an electromagnetic field, was printed on a polyimide flexible laminate substrate to form a sensor to suit a broad range of applications, where a sensor could be placed in water reservoirs or fluid-carrying pipes for continuous analysis. The developed system confirmed the viability of using microwaves for real-time chloride solutions monitoring as the reflected signals represented by S11 parameters were unique with clearly observed shifts in the resonant frequencies and amplitude changes when placed in direct contact with 20 µl of each solution.

A Fluidic Cell Embedded Electromagnetic Wave Sensor for Online Indication of Neurological Impairment during Surgical Procedures

Lactate is known to be an indicator of neurological impairment during aortic aneurysm surgery. It is suggested that cerebrospinal fluid removed during such surgery could provide useful information in this regard. Medical professionals find the prospect of online detection of such analytes exciting, as current practice is time consuming and leads to multiple invasive procedures. Advancing from the current laboratory based analysis techniques to online methods could provide the basis for improved treatment regimes, better quality of care, and enhanced resource efficiency within hospitals. Accordingly, this article considers the use of a low power fluidic system with embedded electromagnetic wave sensor to detect varying lactate concentrations. Results are promising over the physiological range of 0 − 20 mmol/L with a calibration curve demonstrating an R2 value > 0.98.

Time domain reflectometry sensor-assisted freeze/thaw analysis in geomaterials

Freeze–thaw is a major source of damages and deteriorations for infrastructures in cold regions. Most of the existing investigations focus on soil behaviours in the completely frozen or completely thawed state. Tools to assist the determination of freeze/thaw status and its effects on geomaterials including soils are currently rare. This paper firstly introduced the design of an innovative guided electromagnetic wave sensor called Time Domain Reflectometry (TDR) tube that can non-destructively monitor the freeze/thaw process in standard sized soil specimens. An analysis algorithm was presented for interpreting TDR signals accordingly to determine the degree of freeze/thaw. The determined freeze/thaw statuses were then compared with deformation moduli obtained with compression test. An empirical relationship for freeze–thaw status-dependent mechanical properties was proposed based on the experimental observation. On the other hand, a framework of sensor-assisted analysis of freeze/thaw effects on soils was established. The framework concentrates on mechanical behaviours including stresses and deformations which are responsible for the distresses in the infrastructures. Poroelastic relationships, macro–micro relationship and the thermal dynamic equilibriums between phases were incorporated to obtain a close form solution for the simulation model. A simple case study was conducted to demonstrate the fusion of sensor data and computational simulation to investigate the freeze/thaw effects on soils.