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The preference of the proper distribution for modelling data is often a substantial concern to researchers and practitioners. For this reason, new statistical distributions or the generalizations of well-known distributions have been proposed for exible modeling. Weighted distributions are one of the generalization methods for these distributions. In this article, we proposed e new discrete distribution which takes length and area biased exponential distributions as an underlying distribution. Main statistical properties of these proposed distributions are obtained and real-life examples which have been used in literature are used for illustration of these distributions.

The preference of the proper distribution for modelling data is often a substantial concern to researchers and practitioners. For this reason, new statistical distributions or the generalizations of well-known distributions have been proposed for exible modeling. Weighted distributions are one of the generalization methods for these distributions. In this article, area biased beta, Rayleigh and log-normal distributions are introduced. Some main statistical properties, like probability density functions, cumulative distribution functions, moments and the estimation of the parameters of these distributions are obtained. Real data examples are used for illustration of these distributions.

Time series analyzing is very important tool for economic and financial system. However, recent developments show that financial systems are known in a structural change. Therefore, nonlinear time series have been analyzed for past decades because of these changes. In this paper, we consider Threshold Autoregressive (TAR) model. The most popular method for estimating the parameters and threshold value is least square (LS) method. However, LS method is not robust to the outliers and departures from normality. Therefore, we propose a robust version of estimation in order to provide robust results. JEL classification numbers: C01, C22, C13. Keywords: Threshold Autoregressive Model, Iterated Weighted Least Square, Skew Normal, Long Tailed Symmetric Distribution, Robustness.

Background & objective: Corona pandemic has had profound effects on the practice of healthcare delivery across the globe. The institutional practices and protocols had to be rewritten to cope up with the surge of corona patients and to save the staff and the non-corona patients. We evaluated the emergency surgery cases during the first wave of COVID-19 after the decision to stop elective surgeries, in regard to differences in terms of case distribution, patient profile, anesthesia methods used and the management, and compared with an equivalent period before the pandemic. Methodology: Patient files related to emergency surgery from October-November 2019 and April-May 2020, were retrospectively evaluated. Assessment parameters included age, gender, surgical discipline, ASA score, type of anesthesia, time to discharge, reoperation, laparoscopic or open surgery. Results: The most common surgical cases in both periods belonged to general surgery. While the number of patients in ASA-I decreased during the COVID period, those in ASA-II increased. We found that while general anesthesia was preferred in majority of the surgeries during the non-COVID period, spinal anesthesia gained popularity in the COVID period (p < 0.05). Conclusion: The decrease in the number of patients with ASA-I indicates a change in the surgeons’ priorities in emergency surgery cases. Although there is a worldwide approach to the use of laparoscopic surgery, the use of open surgical techniques increased in our hospital. Key words: Covid-19; Pandemic, Emergency surgery Citation: Akcaalan Y, Erkilic E, Gulec H, Gumus T, Ozturk L, Kayan G, Kanbak O, Celik N. Effects of the COVID-19 pandemic on the approach to emergency surgery: a comparative study. Anaesth. pain intensive care 2022;26(3):469-473; DOI: 10.35975/apic.v26i4.1949 Received: Sep 29, 2021; Reviewed: Jan 10, 2022; Accepted: Mar 26, 2022

The pairwise comparisons or post-hoc methods are used for determining the source of the difference of group means in one-way ANOVA. These methods are mostly depend on normality assumption. However, nonnormal distributions are more prevalent than normal distribution. Therefore, robust estimation methods become very important tools in statistical analysis. In this paper, we assume that the distribution of the error terms is Azzalini's skew $t$ and obtain the robust estimators in order to make post-hoc tests in one-way ANOVA. We use maximum likelihood (ML) methodology and compare this methodology with some of robust estimators like M estimator, Wave estimator, trimmed mean and modified maximum likelihood (MML) methodology with Monte Carlo simulation study. Simulation results show that the proposed methodology is more preferable. We also compare power values of the test statistics and conclude that the test statistics based on the ML estimators are more powerful than the test statistics based on other methods.

The arcsine distribution is very important tool in statistics literature especially in Brownian motion studies. However, modelling real data sets, even when the potential underlying distribution is pre-defined, is very complicated and difficult in statistical modelling. For this reason, we desire some flexibility on the underlying distribution. In this study, we propose a new distribution obtained by arcsine distribution with Azzalini’s skewness procedure. The main characteristics of the proposed distribution are determined both with theoretically and simulation study.

In this article, it is assumed that the distribution of the error terms is the Birnbaum-Saunders distribution in the process of one-way ANOVA. The Birnbaum-Saunders distribution has been widely used in reliability analysis especially in fatigue-life models. In reliability analysis, nonnormal distribution is much more common than the normal distribution. We obtain the estimation of the parameters og interest by maximum likelihood method. We also propose new test statistics based on these estimators . The efficiencies of the maximum likelihood estimators and the Type I errors obtained by using the proposed estimators are compared with normal theory via Monte Carlo simulation study. At the end of the study, the real life example is given just for the illustration of the method.

First of all, we establish an identity for higher-order differentiable functions. Then, we prove some integral inequalities for mappings that have continuous derivatives up to the order $n-1$ with $n\geq 1$ and whose n-th derivatives are the element of $L_{1}, ~L_{r}$, and $L_{\infty }.$ In addition, estimates of new composite quadrature rules are examined. Finally, natural applications for exponential and logarithmic functions are given.

Censoring can be occurred in many statistical analyses in the framework of experimental design. In this study, we estimate the model parameters in one-way ANOVA under Type II censoring. We assume t...

In this article, we assume that the distribution of the error terms is skew t in two-way analysis of variance (ANOVA). Skew t distribution is very flexible for modeling the symmetric and the skew d...

Smart antenna systems utilize space-division multiple access (SDMA) to allow multiple users to simultaneously access the limited wireless spectrum, hence increasing the data rates, quality, and performance of wireless systems. On the other hand, the additional hardware/software requirements of the smart antenna systems and the associated costs hinder the application of this promising technology in commercial wireless communication systems. To alleviate these cost issues, the hybrid smart antenna array (HSAA) is proposed as a low-cost, high-performance adaptive beamforming algorithm combining the advantages of antenna switching and adaptive digital beamforming. By using directive antennas as array elements with optimized element tilt angles and selecting a subset of the array elements for beamforming, the hardware and computational costs are significantly reduced. An array optimization approach using a genetic algorithm (GA) was developed to find the optimal tilt angles of the directional elements on the array, given the directional antenna patterns and the number of array elements used in beamforming. Computer simulations as well as experiments with 2.4 and 60 GHz receivers implementing the HSAA with the GA-optimized arrays showed that a similar performance to a fully adaptive system can be achieved by using a subset of the array elements with increased convergence speed.

The development and use of genetic programming (GP) software to synthesize true-3D artificial magnetic conductor (AMC) ground planes is presented, with the focus on achieving a lower frequency response (particularly in the high VHF to low UHF bands), low-profile, broadband designs without the use of absorbing or magnetic materials. Metallic 3D patterns are embedded in one or more substrate layers with a PEC bottom, and the patterning in the unit cell is allowed to extend into neighboring unit cells, thus achieving a lower frequency response with much smaller unit cell size and thickness. Four designs synthesized using the developed GP software are presented with achieved bandwidths ranging from 32.7% to 71.1% when using the ±90 ° reflection phase criterion. Further, it is shown that through the use of a parametric study, the center frequency (0 ° reflection phase) of one of the designs can be reduced from 381.3 MHz to 87.8 MHz, which is a 77% reduction. The edge of the square unit cell size for this miniaturized design is λ0/51 and the thickness is λ0/61 at 83.9 MHz.

In this letter, a realistic method for feeding the dual-polarized cylindrical long-slot array (CLSA) antenna is presented. A compact lumped-element balun with 2.5:1 bandwidth is designed, fabricated, measured, and used for feeding the dipole-mode, while a compact microstrip coupled-line impedance transformer is used for feeding the slot mode of the antenna. Simulation results of these feeds are compared to experimental measurements, and the overall performance of the dual-polarized CLSA antenna with these feeds is also simulated. Simulation results agree with measured data, and it is shown that this antenna has the capability of achieving four polarization modes [vertical, horizontal, left-handed circular polarization (LHCP), right-handed circular polarization (RHCP)]. The gain over 225-450 MHz ranges from -1.42 to -3.15 dBi for the dipole mode, -0.44 to -2.24 dBi for the slot mode, -1.76 to -2.70 dBic for the LHCP mode, and -1.80 to -2.68 dBic for the RHCP mode.

The purpose of this study was to investigate the relationship between the self-esteem and the social value size of national youth judo team athletes. Data were collected by Coopersmith Self-Esteem Inventory adapted to Turkish by Özoğlu (1988) and Multidimensional Social Values Scale developed by Yavuz Bolat (2013) with a questionnaire developed by the researchers to gather personal information. Working group of the research consist of Turkish youths (15-19 years old) are struggling in national judo team between 2015-2016 year in a total 118 athletes including 58 women and 60 men. Data were analysed by using SPSS 20 statistical programme, with oneway anova test. Results showed that there is a positive relation between the selfesteem and the social value size that family values, religious values, traditional values, scientific values but political values have not found a significant relationship between self-esteem. As a result of that social value perceptions effect on self-esteem levels of young national judoka and that correlates positively with each other. ÖzetBu araştırmanın amacı genç milli judo takım sporcularının sahip oldukları sosyal değer boyutları ile özsaygı düzeyleri arasındaki ilişkiyi incelemektir. Katılımcıların sosyal değer boyutlarının ve özsaygı düzeylerini belirlemek için araştırmacılar tarafından geliştirilen Kişisel Bilgi Formu ve Coopersmith (1959) tarafından geliştirilen, ülkemizde Özoğlu (1988) tarafından geçerlilik ve güvenilirlik çalışması yapılan ‘Benlik Saygısı Envanteri (Coopersmith Self-Esteem Inventory) ve Yavuz Bolat (2013) tarafından geliştirilen Çok Boyutlu Sosyal Değerler Ölçeği (Multidimensional Social Values Scale ) uygulanmıştır. Araştırmanın çalışma grubunu 2015-2016 yılları arasında Türk genç (15-19 yaş arası) milli judo takımında mücadele eden 58 kadın 60 erkek olmak üzere toplam 118 sporcu oluşturmaktadır. Araştırmanın verileri SPSS 20 istatistik programı kullanılarak, çözümlemeler için oneway anova testi kullanılmıştır. Elde edilen bulgularda sosyal değer boyutları olan aile değerleri, dini değerler, geleneksel değerler, bilimsel değerler ve çalışma değerleri ile özsaygı düzeyleri arasında pozitif yönlü anlamlı bir ilişkiye rastlanırken siyasi değerler ve boyutu ile özsaygı arasında anlamlı bir ilişkiye rastlanmamıştır. Sonuç olarak genç milli judocularda sosyal değer algılarının özsaygı seviyeleri üzerine etkisinin olduğu ve birbirleri ile pozitif yönde paralellik gösterdiği söylenebilir.

Two wideband cylindrical long-slot antenna arrays (CLSAs) integrated with hybrid electromagnetic band-gap (EBG)/ferrite ground planes are designed for communication applications in 150-600-MHz (lower) and 0.7-6.5-GHz (upper) bands. The CLSA designs are compact, the lower and upper bands designs' dimensions being 78 × 63 cm2 (height × diameter and 29 × 48 cm2, respectively. The hybrid EBG/ferrite ground plane, previously developed and experimentally verified by the authors for planar arrays, was used to both eliminate the slot radiation toward the center of the cylinder and was found to be also important in enhancing the wideband properties of the array. Simulation results show that, under normal operation mode (all array elements have equal phases), the CLSA produces omnidirectional coverage over a wide bandwidth. In challenging environments, the CLSA can also be used in the phased array mode to produce directive and steerable beam patterns. In phased array mode, the beam can be steered 360 ° field of view (FOV) in azimuth without any distortion in the beam pattern and with more than 10 dB gain increase over the normal operation mode.

Emerging homeland security applications require low-cost and fast, deployable, high-frequency (HF) radar systems and the ability to operate in challenging terrain environments. With the need to cover as many border and coastal areas as possible, taking advantages of available transmitter resources to track targets using passive radar technologies is yet another area of research of considerable interest. In this paper, we describe the development of an HF radar system that meets these operational challenges, and we also highlight some recent implementation of the passive radar technology for homeland security applications. Specifically, we describe the design of a novel, electrically small HF antenna system consisting of three helical elements, one connected to the feed port while the other two are folded arms terminated with switchable loads. The antenna is 0.90-m (ka range from 0.44 at 30 MHz down to 0.08 at 5.7 MHz. The achieved bandwidths range from 1.4% up to 12% and associated efficiencies range from 66.2% to 76% within the HF band (3‐30 MHz). As for the operational requirement in challenging terrain environments, a setup in a hilltop-type environment with a slope terrain and surface roughness was considered. A propagation modeling and ray-tracing approach was used to evaluate the impact of such terrain conditions on the effective interelement spacing of an HF radar antenna array and the subsequent impact on its beamforming and beam steering performance. It is shown that while the effect of the slope on the effective interelement spacing of the array could be very significant, diffraction effects from surface roughness resulted in a much smaller, but significant, error of about 18°. Results from some initial work on the implementation of passive radar technology, with focus on addressing the bandwidth requirement to ensure practical resolution values, are also described. It is shown that signals from wide-band transmitters (e.g., High Definition Television [HDTV] signals) rather than those from radio stations are required to provide acceptable range resolution. These as well as simulation and experimental results of the antenna design, and results from beamforming simulations illustrating the effect of a rough hilltop terrain on the HF radar performance are described.

Emerging homeland security applications require low-cost and rapid installation of HF radar systems in challenging terrain environments. One example concerns hills with natural slope and surface irregularity and roughness. In this letter, through the investigation of radio-wave propagation in such an environment, we examine the effect of the slope and surface roughness of the terrain on the performance of HF radars. It is shown that the slope and surface irregularity affect the effective electrical spacing between array elements and cause beamforming and scanning errors, which lead to misdetection of targets. It is also shown by an investigation of an actual HF radar site in the area of Koko Head in Hawaii that scattering from surface roughness of the terrain adds extra error to the phase difference between antenna array elements (~30°), hence degrades the radar performance further.

The use of the noninvasive microwave method for measuring changes in lung water content has been previously reported and validated in animal experiments. The approach is based on measuring the transmission coefficient across the thorax and correlating results with changes in lung water content. In this letter, we extend this technique to the monitoring of multiple vital signs including heart rate and breathing as well as the changes of lung water content from a single transmission coefficient measurement. Using a short-time Fourier transform-based digital signal processing method, it is shown that these vital signs can be accurately detected and extracted from a single microwave transmission coefficient measurement. Experimental measurements were made on a thorax phantom model, and the obtained data confirmed the validity and accuracy of the proposed approach. The radiation bio-safety aspects of this approach were evaluated using a DASY4 near-field scanner, often used for certifying cell phones. Obtained results for a 30-mW input power show that the specific absorption rate (SAR) values are about one third of the FCC safety standard at the operating frequency of 915 MHz. The microwave applicator design together with the experimental procedure and the extracted vital signs results are presented, and avenues for future clinical implementation are discussed.

A novel design for an electrically small high-frequency (HF) antenna suitable for coastal radar applications is presented. The principle design objectives were to develop an HF antenna resonant at multiple frequencies that is also compact and easily transportable for deployment to coastal sites and on floating platforms. The compact antenna achieves practical performance values for radiation resistance, bandwidth, and gain while maintaining small values of ka. The design presented in this letter consists of a meandering line antenna composed of helical elements and switchable folded arms. The value of ka ranges down to 0.16 at 5.7 MHz. The antenna is self-resonant at multiple frequencies including 5.7, 16.1, 20.6, and 28.1 MHz for open-circuit mode and 15.1, 18.5, and 26.1 for the short-circuit mode. In all cases, input impedances were easily matched to 50-Ω coaxial feed lines, and the achieved bandwidths ranged from 1% to 12% within the HF band (3-30 MHz). The antenna is 90 cm high with a small ground disk of 60 cm diameter. Simulation results and prototype experimental measurements are presented.

The hybrid smart antenna approach utilizes a subset of array elements selected according to the receive signal strengths to perform beamforming, thus improving the computational efficiency, and reducing the hardware implementation cost. The previous implementations and published experimental results of this algorithm have been based on continuous-wave (CW) transmit signals, and without modulation. In order to verify the operation of the hybrid smart antenna algorithm with modulated waveforms, the developed 2.4- and 60-GHz testbeds are modified to generate and receive data modulated waveforms. The modifications also include the use of preamble bits at the beginning of each data frame transmitted, and implementation of a sliding window correlator at the receiver to synchronize with the data frames. Binary phase shift keying (BPSK) modulation is used with a 1 megabit per second (Mb/s) data rate for information transfer. The obtained beam patterns agree well with the theoretical results thus verifying the developed hybrid smart antenna algorithm.

With the introduction of the unlicensed spectrum at the 60 GHz range, the development of communication systems with data rates in Gb/s range has become feasible. However, there are quite significant challenges at this frequency range such as high propagation loss, oxygen absorption, antenna alignment and unavailability of high-gain, high power circuit elements. In this paper we present a novel 2-channel hybrid smart-antenna system operating at 60 GHz band which can be used with an antenna switching system to improve the signal power performance and to serve as an automated alignment system. The critical system parameters for a smart-antenna system at this frequency are the transmitter to receiver distance, element spacing, and antenna beamwidth. As the widely known beamforming assumptions may not hold for some configurations, a more general beamforming formulation is given in the paper to serve as a guideline for system designers. The twist angle of array elements is introduced as a new array design parameter. By selecting the optimal twist angle to help overlap radiation patterns, the fine alignment of the transmit and receive beams is established electronically using beamforming, thus reducing the cost of deployment and maintenance of the 60 GHz indoor communication systems.

The previously described hybrid smart-antenna system solves the transmitter receiver alignment problem of 60-GHz wireless systems when high gain antennas are used. Utilizing multiple highly directional array elements and coherently combining the outputs of a few elements adaptively, the hybrid smart antenna achieves the desired performance and results in significant hardware cost and computational complexity savings. For optimal alignment, however, the output power of the hybrid smart antenna should stay constant over the scanning range. This minimizes the so-called scalloping effects and necessitates a careful selection of the array elements being used in beamforming. In this letter, a genetic-algorithm solution to optimally adjust the beam pattern overlaps the array elements to minimize the output-power fluctuations in a given scan range. It is shown that while the hybrid algorithm may perform satisfactorily with less than one-third of the total number of the array elements (e.g., two or three elements in an array of ten antennas), there is an optimal number of elements for a given array that provides minimal power fluctuation in a specified scan range. A tradeoff between the acceptable level of power fluctuation and the total received power is identified.

International Conference on Advances in Natural and Applied Sciences (ICANAS) -- APR 21-23, 2016 -- Antalya, TURKEY WOS: 000376001000041 In statistical applications, some data set may exhibit the features like high skewness and kurtosis and heavy tailness that are incompatible with the normality assumption especially in finance and engineering. For these reason, the modeling of the data sets with alpha stable distributions will be reasonable approach. The stable distributions have four parameters. In literature, the estimation methods have been studied in order to estimate these unknown model parameters. In this study, we give small information about these proposed estimation methods and we compare these estimators with respect to robustness properties with a comprehensive simulation study, since the robustness property of an estimator has been an important tool for an appropriate modeling.

International Conference on Advances in Natural and Applied Sciences (ICANAS) -- APR 21-23, 2016 -- Antalya, TURKEY WOS: 000376001000076 The main aim of the present paper is to introduce phi(h)-convex stochastic processes and we investigate main properties of these mappings. Moreover, we prove the Hadamard-type inequalities for phi(h)-convex stochastic processes. We also give some new general inequalities for phi(h)-convex stochastic processes.

We study the behaviour of trimmed likelihood estimators (TLEs) for lifetime models with exponential or lognormal distributions possessing a linear or nonlinear link function. In particular, we investigate the difference between two possible definitions for the TLE, one called original trimmed likelihood estimator (OTLE) and one called modified trimmed likelihood estimator (MTLE) which is the finite sample version of a form for location and linear regression used by Bednarski and Clarke [Trimmed likelihood estimation of location and scale of the normal distribution. Aust J Statist. 1993;35:141–153, Asymptotics for an adaptive trimmed likelihood location estimator. Statistics. 2002;36:1–8] and Bednarski et al. [Adaptive trimmed likelihood estimation in regression. Discuss Math Probab Stat. 2010;30:203–219]. The OTLE is always an MTLE but the MTLE may not be unique even in cases where the OLTE is unique. We compare especially the functional forms of both types of estimators, characterize the difference with ...

Phased array antennas have and will continue to be a critically important component in the development of future wireless systems with applications in communications, radar, and satellite technologies. In spite of the significant advances in the design of modern phased array antennas, there continue to be significant and growing need for developing high performance systems that are also low cost and with beam steering capabilities. In this paper we describe some of the antenna array designs that focus on achieving this goal. We will start with one approach that is based on an analog phase-shifting approach and involves an integrated use of ferroelectric materials and the Continuous Transverse Stub (CTS) antenna array technologies. A complementary design which is based on digital beamforming and the utilization of the Hybrid Smart Antenna technique recently developed by our group will then be described. This will be followed with comments regarding the trade-off between the analog and digital phase shifting techniques. We will conclude the chapter with a description of a novel ultra-wideband and low profile ground plane which is based on a hybrid ferrite and Electromagnetic Band Gap (EBG) materials design. In all cases simulation results and experimental validation, whenever available, will be presented and aspects of the required future work to fully enable these technologies will be discussed.

The aim of this study is to reveal the major determinants which have impact on financial performance of paper and paper products firms listed in Borsa Istanbul. We examined the impact of the firm specific, industry specific and macroeconomic factors on Return on Assets and Return on Equity in paper and paper products firms listed in Borsa Istanbul during the period from 2011/01 to 2014/09 by using panel regression. The results show that except for Sales to Asset Ratio, firm specific and industry specific factors have statistically significant and material impact on both financial performance indicators. As macroeconomic factor, the impact of foreign trade deficit on the performance indicators is relatively weak. Through macroeconomic variables, commercial loan interest rate has no statistical significance for both ROA and ROE. The empirical result suggests that the impact of the variables on ROE is stronger compared to ROA.

In the literature (Zhang et al., and Rezk et al.), a hybrid beamforming algorithm utilizing a subset of array elements according to receive signal strength is proposed. The algorithm utilizes a smart switch which selects a subset of antennas that receive the signals with higher strength and a beamforming algorithm is performed to calculate the weights for the selected antennas. Since earlier results were based on simulations by Zhang et al., and Rezk et al., in this letter we present experimental results of testing a smart-antenna prototype with an eight-element array. This array is designed and implemented by the authors to verify the accuracy and performance of the proposed hybrid-beamforming algorithm. In general, the experimental results confirmed the simulation data. Specifically, it is shown that the proposed hybrid algorithm using a subset of the array has nearly the same performance as the adaptive system with the full array. Tradeoffs regarding beamwidth and the sidelobe levels are confirmed and additional experimental results illustrating the angle resolution of the developed system are presented

The development and use of genetic programming (GP) software to synthesize true-3D artificial magnetic conductor (AMC) ground planes is presented, with the focus on achieving a lower frequency response (particularly in the high VHF to low UHF bands), low-profile, broadband designs without the use of absorbing or magnetic materials. Metallic 3D patterns are embedded in one or more substrate layers with a PEC bottom, and the patterning in the unit cell is allowed to extend into neighboring unit cells, thus achieving a lower frequency response with much smaller unit cell size and thickness. Two designs synthesized using the developed GP software are presented with achieved bandwidths of 71.1% and 51.6% when using the ±90° reflection phase criterion.

Cognitive radio systems adaptively adjust their radio parameters based on the feedback from the electromagnetic environment. Therefore, it is expected that cognitive radio systems will have better performance if they are integrated with accurate site-specific propagation modeling. Our group has long standing expertise in propagation modeling utilizing geo-spatial tools and indoor building models, and has focus on integrating these models as part of the environment awareness engine in cognitive radios. In this paper, we present the preliminary results for a multi-antenna based spectrum sensing algorithm with adaptive thresholds. The results show that, an almost fixed detection rate of 85% can be achieved for a mobile cognitive radio in an urban environment when the thresholds are set based on the path loss information provided by site-specific propagation modeling. On the other hand, the spectrum sensing algorithm with a fixed threshold shows a great variability in the detection performance, going as low as 65% in regions with heavy fading, which leads to harmful interference.

The authors have previously proposed and experimentally verified a microwave medical sensor for monitoring vital signs including the lung water content. It is proposed that, with a careful and medically based designed array of such sensors, both surface and in-depth vital signs can be extracted accurately. For such array design, realistic human models can be used in full-wave simulators with the help of medical personnel. In this paper, the feasibility of detecting the edema in the lungs using the proposed microwave measurement method is studied using realistic human models in full-wave electromagnetic simulators (HFSS). Simulation results show that, the reflection and transmission coefficient phase exhibits a change with the increasing amount of edema as a proof of concept. The sensitivity and measurement accuracy can be increased by including the transmission coefficient measurements and further by using medically based designed sensor array.

A new L-band long slot antenna array design is described. Besides the use of long slot array to provide dual polarization radiation pattern in the 1-2 GHz band, the antenna is integrated with a metamaterial ground plane to provide compact design and improved gains. Simulation results of S-parameters and radiation patterns will be presented and the design trade-off will be discussed in details.

Previously developed MATLAB code for designing planar (2D) metamaterial broadband ground planes is extended to design volumetric (3D) metamaterial structures. A 3D ground plane designed to operate as an artificial magnetic conductor (AMC) in the 225-450 MHz frequency range is presented. Its performance when used as the ground plane of the planar long slot array (PLSA) antenna and cylindrical long slot array (CLSA) antenna is evaluated and compared to the previously used absorbing ferrite ground plane, resulting in enhanced gain performance due to in phase reflection and minimal absorption.

This paper describes a new microwave-based method and associated measurement system for monitoring multiple vital signs (VS) as well as the changes in lung water content. The measurement procedure utilizes a single microwave sensor for reflection coefficient measurements, hence the name "microwave stethoscope (MiSt)," as opposed to the two-sensor transmission method previously proposed by the authors. To compensate for the reduced sensitivity due to reflection coefficient measurements, an improved microwave sensor design with enhanced matching to the skin and broadband operation, as well as an advanced digital signal processing algorithm are used in developing the MiSt. Results from phantom experiments and human clinical trials are described. The results clearly demonstrate that MiSt provides reliable monitoring of multiple VS such as the respiration rate, heart rate, and the changes in lung water content through a single microwave measurement. In addition, information such as heart waveforms that correlates well with electrocardiogram is observed from these microwave measurements. Details of the broadband sensor design, experimental procedure, DSP algorithms used for VS extraction, and obtained results are presented and discussed.

The MiSt measurement procedure for vital signs monitoring is based on the microwave reflection coefficient measurements on the patient chest using a novel microwave sensor. It is shown that MiSt provides integrated, multi-purpose, low-cost and non-invasive vital signs sensor that is capable of measuring heart-rate, respiration rate, changes in the lung water content, and the heartbeat waveform. In this paper, the improved microwave sensor design is presented. Human experiments are also conducted in clinical settings and comparisons with commercial FDA approved medical devices (Propaq LT) are given, thus, demonstrating the feasibility of MiSt in accurately detecting multiple VS. According to the human subject experiment results and its comparison with the Propaq data, the accuracy of the MiSt in measuring multiple VS including heart rate (HR), respiration rate (RR), and EKG has been established. Additional measurement capability of the lung water content is an important and unique asset of the proposed MiSt system. These experimental results clearly demonstrate the advantage of extracting multiple VS parameters using only single microwave measurement and make the MiSt a promising technology for implementation of the proactive healthcare delivery methods.

In this paper, preliminary human clinical trial results for the Microwave Stethoscope (MiSt) are presented. Benchmarking results using a Food and Drug Administration approved medical device, Propaq LT, have shown the feasibility of accurately detecting the heartbeat and respiration rates from a single measurement using the MiSt. Additionally and more importantly, the MiSt allows the non-invasive capturing of internal patient data such as the changes in the lung water content as well as the accurate heartbeat waveform that correlates very well with the electrocardiogram (ECG). All these encouraging results suggest that the MiSt has capabilities to monitor multiple vital signs including heart rate and respiration rate, and replace multiple sensors used to monitor heart rate and respiration rate.

The MiSt is a novel non-invasive vital signs sensor that can simultaneously measure and extract multiple vital signs parameters including the heart rate, respiration rate, heart waveform, and changes in lung water content from a single microwave measurement. The microwave applicator used to couple the microwave signal to the patient's chest and to measure the reflection from various body tissues play an important role in the MiSt operation for detecting multiple vital signs. In this paper, the design and characterization results of four different broadband electromagnetic couplers and their inherent tradeoffs are presented and discussed. It is shown that it is possible to achieve more than 10∶1 bandwidth.

In this paper, a dual-polarization ultra-wideband long-slot antenna arrays (LSA) integrated with hybrid electromagnetic band-gap (EBG)/ferrite ground planes is designed for communication radar applications. The dual-polarization was achieved by combining connected dipole and long slot array concept. Connected dipole mode provides horizontal polarization while long slot mode gives vertical polarization. The developed antenna is a cylindrical shape of the LSA with cylindrical EBG/Ferrite hybrid ground plane, which is designed to cover NTDR, and EPLRS bands. This antenna provides the omni directional pattern from 150 to 500 MHz. The hybrid EBG/Ferrite ground plane, previously developed and experimentally verified by the authors for planar arrays, both eliminating the slot radiation toward the center of the cylinder and was important in enhancing the wideband properties of the array. Antenna characteristics of the developed antennas were analyzed by simulations and the simulation results are presented.