Antenna Impedance Matching Using Deep Learning

We propose a deep neural network (DNN) to determine the matching circuit parameters for antenna impedance matching. The DNN determines the element values of the matching circuit without requiring a mathematical description of matching methods, and it approximates feasible solutions even for unimplementable inputs. For matching, the magnitude and phase of impedance should be known in general. In contrast, the element values of the matching circuit can be determined only using the impedance magnitude using the proposed DNN. A gamma-matching circuit consisting of a series capacitor and a parallel capacitor was applied to a conventional inverted-F antenna for impedance matching. For learning, the magnitude of input impedance S11 of the antenna was extracted according to the element values of the matching circuit. A total of 377 training samples and 66 validation samples were obtained. The DNN was then constructed considering the magnitude of impedance S11 as the input and the element values of the matching circuit as the output. During training, the loss converged as the number of epochs increased. In addition, the desired matching values for unlearned square and triangular waves were obtained during testing.

Dielectric Properties of Serum in Children with Suspected Immunodeficiency and Suffering from Recurrent Respiratory Infections

Despite considerable progress in the diagnosis of various diseases, an ideal, simple tool for diagnosing patients with respiratory tract infections has not yet been invented. Many simple diagnostic tests are widely available to most doctors, provided they are aware of the prevalence of primary immunodeficiency. Other, more accurate studies are available only to immunologists. The aim of the study was to investigate the occurrence of dependence between selected physical parameters of serum such as: electrical conductivity, electrical permeability, dielectric loss factor, and selected parameters of the immune system. In addition, we have also included the ionogram (Na, K, Cl, Ca, Mg) and glucose concentration. As a result of research, the statistically significant, but very weak correlations between impedance magnitude |Z| and platelet counts (PLT), mean platelet volume (MPV) and chloride ions (Cl-) were found. The statistically significant differences according |Z| between children with and without deficiency in parameters of the immune system were noticed. Values of |Z| are higher in the case of children without deficiency in parameters of the immune system. The method of impedance measurements presented in our work is significantly easier then biosensors presented by other scientists. Taking into account our results, it can be stated that this method is promising for fast and easy detection of immunological disorders.

Surface impedance properties of a wire grid embedded in a chiral medium

The surface impedance characteristics of a wire grid composed of infinitely long parallel conducting wires embedded in lossless and lossy frequency-dispersive chiral background media have been investigated. Using wavefield decomposition approach for a chiral background and with the application of impedance boundary conditions for a wire grid, an analytic expression for the surface impedance of a wire grid with a chiral background has been derived. It is shown that the surface impedance magnitude of a wire grid with chiral nihility background is close to zero and almost independent of incident polar angles. A strong chiral background significantly enhances the surface impedance magnitude of a wire grid for incident polar angles closer to right angle as compared to the free space background. The same electromagnetic appearance of a wire grid with frequency-dispersive chiral and free space background media at some critical frequency has also been discussed which may find applications in electromagnetic illusions. It is also shown that if the value of incident polar angles are closer to right angle then the impedance magnitude of a wire grid embedded in the realistic chiral background is smaller as compared to the same wire grid when placed in the free space background.

Development of an Ultrasensitive Impedimetric Immunosensor Platform for Detection of Plasmodium Lactate Dehydrogenase

Elimination of malaria is a global health priority. Detecting an asymptomatic carrier of Plasmodium parasites to receive treatment is an important step in achieving this goal. Current available tools for detection of malaria parasites are either expensive, lacking in sensitivity for asymptomatic carriers, or low in throughput. We investigated the sensitivity of an impedimetric biosensor targeting the malaria biomarker Plasmodium lactate dehydrogenase (pLDH). Following optimization of the detection protocol, sensor performance was tested using phosphate-buffered saline (PBS), and then saliva samples spiked with pLDH at various concentrations. The presence of pLDH was determined by analyzing the sensor electrical properties before and after sample application. Through comparing percentage changes in impedance magnitude, the sensors distinguished pLDH-spiked PBS from non-spiked PBS at concentrations as low as 250 pg/mL (p = 0.0008). Percentage changes in impedance magnitude from saliva spiked with 2.5 ng/mL pLDH trended higher than those from non-spiked saliva. These results suggest that these biosensors have the potential to detect concentrations of pLDH up to two logs lower than currently available best-practice diagnostic tools. Successful optimization of this sensor platform would enable more efficient diagnosis of asymptomatic carriers, who can be targeted for treatment, contributing to the elimination of malaria.

SIMULASI PENENTUAN LOKASI GANGGUAN SATU FASA PADA JARINGAN TEGANGAN MENENGAH 20 KV BERBASIS ARDUINO MEGA 2560 DILENGKAPI DENGAN MONITORING MELALUI VTSCADA

Danu Nur Ashifa, Arkhan Subari in this paper explain that in a distribution network of 20 KV, short circuit interference often occurs. Short circuit interference will produce a fault current that is felt by protection equipment. Each fault current will differ depending on the distance of the interference. Determining the distance of interference can not be displayed in SCADA, SCADA will only display the amount of interference and which equipment works. Determination of distance is carried out after analysis by the officer. Based on this matter the compiler makes a simulation tool where the tool can monitor the location of the disturbance from the nearest protective equipment that feels a single phase short circuit interference. The simulation tool consists of Arduino Mega 2560 which functions as a control center. The input used is a potentiometer as a simulator of the impedance magnitude that occurs during a single phase short circuit where the potentiometer will provide input in the form of a signal. And Omron LY2N relay which functions as protection equipment. After the experiment, the results obtained are that the tool can determine the location of interference from the nearest protection equipment based on changes in the bits read by Arduino. The larger the bits read by Arduino, the more distant the interference occurs from the protection equipment. 125 bits will produce an Arduino impedance calculation of 2.6 ohms so that the fault location is 0 km from PMT while 1023 bits will produce an impedance calculation of 21.30 ohms so that the fault location is 4.5 km from SSO.

Electrical Impedance-Based Methodology for Locating Carcinoma Emulators on Breast Models

There is a worldwide need for new methodologies to prediagnose breast cancer in an early stage, which helps to notably increase the possibility of saving the mammary gland or patient’s life. This work describes a new methodology proposal based on electrical impedance for the localization of preclinical carcinoma emulators in agar phantoms of the breast. The impedance is systematically measured through eight Ag/AgCl electrodes uniformly distributed in a ring arrangement placed on the breast agar phantom. The fundamental idea of the proposed location algorithm, named Anomaly Tracking Circle algorithm, is to find the breast agar area defined by straight lines joining the electrode pairs having the minimum difference value of the defined normalized impedance magnitude along the measurement sweep. Such difference is obtained with respect to a breast agar phantom without carcinoma emulator. The proposed methodology was evaluated through seven experimental agar models, six of them having carcinoma lobe emulators with different locations and electrical conductivities. According to the obtained results, the described methodology can obtain the location zone of preclinical-emulated carcinomas with an 83.33% success.

The effect of precipitation and deposition layer growth on impedance measurements

The objective of the study was to examine how precipitation and deposition layer growth in an electrochemical cell impact impedance measurements. A measurement system, based on Electrochemical Impedance Spectroscopy (EIS), was used to observe the impedance of an electrochemical cell while precipitation was occurring. The measurement system was also used together with measurements of the solution concentration (in parts per million, ppm) to examine what impact deposition layer growth has on an electrochemical cell. Experimental results indicate a measurable change in the impedance magnitude as the ionic concentration is altered through precipitation. A change in both impedance magnitude and the interfacial capacitance was observed when a deposition layer was established within an electrochemical cell. Results show that impedance measurements are susceptible to changes in solution conductivity and to the presence of a deposition layer in an electrochemical cell. Impedance measurements may be used as an indicator for deposition layer growth, but changes in the solution concentration should be considered when creating a model.

Preliminary studies on monitoring fouling layers on a charged electrode using Electrical Impedance Spectroscopy

The objective of the study described in this paper was to examine whether fouling on an electrode surface can be monitored through impedance measurements using a modified Electrochemical Impedance Spectroscopy technique. The attempt was to evaluate a measurement system that could monitor fouling, within an electrochemical cell, by using EIS to find one single frequency to measure the impedance magnitude. An electrical potential difference was applied to the electrochemical cell to generate an electrical field to accelerate the deposition layer growth on one electrode. Experimental results show that the magnitude of the electrochemical cell impedance was in the range of 110 Ω over the duration of the experiment, which lasted one week. A measurable change in the impedance magnitude was detected when a deposition layer, caused by fouling, was present on one of the electrodes. The measurement frequency was selected specifically for the purpose to increase the deposition layer influence on the measured impedance magnitude, which was achieved by selecting a frequency that kept the capacitive reactance as low as possible. Results indicate that a measurement system, using one frequency, is capable of monitoring the deposition layer by measuring the magnitude of the electrochemical cell impedance.