Direction Finding Research Articles

Electrodynamic modeling of a four-channel antenna with an operating frequency band of octave

The actual problem of electrodynamic modeling of a four-channel antenna with an octave operating frequency range has been considered. The results of numerical electrodynamic modeling of a four-channel antenna have been presented. The considered antenna with an octave operating frequency range is a rectangular curtain comprising four independent non-equidistant channels. Numerical electrodynamic modeling of a four-channel antenna has been carried out in the ANSYS HFSS software package, with the convergence parameter DeltaS = 0.01. As a result of the simulation, the frequency characteristics of each channel have been obtained: VSWR, gain, reflection coefficient, directional pattern. The antenna provides a scanning angle as part of an ultra-wideband digital antenna array of at least ±30° in azimuth and from 0° to 60° in elevation. The gain of the antenna channels in the operating frequency range is not lower than 6 dB. According to the simulation results, the VSWR of each channel of the antenna in the operating frequency range does not exceed 2.55. To minimize the influence of mutual coupling of channels on the antenna characteristics, the distance from the phase centers of the curtain emitters to other elements of the ultra-wideband digital antenna array should be at least a wavelength in free space at the lower frequency of the operating frequency range. It has been shown that the considered four-channel antenna provides an octave operating frequency band and can be used as part of an ultra-wideband digital antenna array for direction finding of radiation sources.

An evaluation of sexual function and health-related quality of life following laparoscopic surgery in individuals living with endometriosis.

What is the relationship between sexual function, health-related quality of life (HRQoL), and laparoscopic surgery in individuals living with endometriosis? A higher number of laparoscopic surgeries is significantly associated with poorer HRQoL and greater levels of sexual dysfunction in individuals with endometriosis. Prior research indicates that endometriosis is associated with lowered HRQoL and sexual function and that these outcomes are influenced by endometriosis-related symptom profiles, medical, and surgical management. A limited number of studies have examined changes in sexual function in individuals with endometriosis following laparoscopic surgery or following repeated surgeries. A cross-sectional community-based online survey was used to examine the relationships between sexual function, HRQoL, and laparoscopic surgery (n = 210). Individuals with a self-reported diagnosis of endometriosis were recruited via online advertising through social media and gynaecology clinics. Endometriosis-specific data (e.g. diagnostic delay, symptom experience) was collected in addition to engagement with laparoscopic surgery, level of HRQoL (EuroQol-5 Dimension: EQ-5D-5L), and sexual function (Female Sexual Function Index: FSFI). Bivariate correlational analyses and hierarchical multiple regression were used to determine the associations between the variables of interest. Individuals with endometriosis have substantially poorer HRQoL in comparison to Australian normative samples, with greater levels of endometriosis-related symptom burden, distress, and pain significantly associated with lower levels of HRQoL. The mean FSFI score was suggestive of clinically significant female sexual dysfunction, with the lowest level of function noted in the domain of sexual pain and the highest level of function noted in the sexual satisfaction domain. A greater number of laparoscopic surgeries was significantly associated with poorer overall HRQoL and greater levels of sexual dysfunction. The cross-sectional nature of the data precludes direct findings of causality and further longitudinal research is recommended. The information pertaining to engagement in laparoscopic surgery was self-report in nature and was not medically verified. The study's findings highlight the pervasive impact of endometriosis on all domains of living, emphasizing the need to extend treatment planning beyond that of physical pain management alone. Early referral for assessment and management of sexual wellbeing is recommended prior to, and post-surgical intervention, with a focus on maintaining post-surgical changes, potentially reducing the need for multiple surgeries. The study was not associated with research funding. Author CN reports grant funding from the Australian Government and Medical Research Future Fund (MRFF) and was a previous employee of CSL Vifor (formerly Vifor Pharma Pty Ltd). N/A.

Effect of COVID-19 fear on nurse performance through insecurity and job satisfaction

Apart from physical health problems, the COVID-19 outbreak also affected psychological health, causing extreme fear of this pandemic. Thus, this study aims to investigate the relationship between nurse performance and the fear of COVID-19 mediated by job insecurity and job satisfaction with conservation of resources theory as the lens. Data from 260 nurses were collected through an online structured questionnaire and analyzed using structural equation modeling-partial least squares. The direct effect findings show that COVID-19 fear influences job insecurity (p < 0.05) but does not influence job satisfaction and nurse performance (p > 0.05). Besides, job insecurity significantly influences job satisfaction and nurse performance (p < 0.05). On the other hand, job satisfaction has no effect on nurse performance (p > 0.05). Then, the indirect effect results show that job insecurity fully mediates the influence of COVID-19 fear on job satisfaction and nurse performance (p < 0.05). Likewise, job satisfaction partially mediates the influence of job insecurity on nurse performance (p < 0.05) but does not mediate the fear of COVID-19 on nurse performance (p > 0.05). These findings provide evidence that the fear of COVID-19 plays an essential role for job insecurity, influencing job satisfaction and nurse performance. These results can develop strategies for better human resource management in nursing staff and provide pragmatic insight into the impact of the COVID-19 pandemic. AcknowledgmentThe authors thank Universitas Negeri Padang for its support in completing this article. We also thank all members for their support and cooperation.

Non‐Hermitian Broadside Coupled Split Ring Resonators with Directional Sensitivity

AbstractDirectional radiofrequency (RF) sensing, also known as radio direction finding, is essential in various applications that involve localizing RF sources. However, existing RF sensing technologies face challenges due to their large antenna sizes and complex RF signal processing circuits, which hinder the realization of miniaturized subwavelength direction sensors. In this article, a non‐Hermitian broadside coupled split ring resonators (BC‐SRRs) are presented, which can identify the direction of an incident RF signal with angles ranging from 0° to 180°. The non‐Hermitian Hamiltonian of the system, which can be interpreted by the temporal coupled mode theory, gives rise to asymmetric resonant modes of the BC‐SRRs. The asymmetry allows the direct measurement of RF wave incident angle by probing the resonant strength of the two BC‐SRRs. For the proof of concept, a one‐stage Dickson voltage multiplier is employed to rectify the RF signals and demonstrate angle sensing ability by relating the rectified voltage to the incident angle. The results showcase the potential of the proposed technique using non‐Hermitian BC‐SRRs as a pathway toward subwavelength antenna‐based radio direction finding.

Development of the national consensus statement on ear health and hearing check recommendations for Aboriginal and Torres Strait Islander children aged under 6 years attending primary care: systematic scoping review and e-Delphi

BackgroundEarly detection of long-term, often asymptomatic, middle ear infection in young Aboriginal and Torres Strait Islander children is more likely to be achieved when ear health and hearing checks are routinely undertaken in primary healthcare. Evidence consistently demonstrates the adverse impacts of this condition on the development and wellbeing of children and their families. We aimed to develop feasible, evidence- and consensus-based primary healthcare recommendations addressing the components and timing of ear health and hearing checks for Aboriginal and Torres Strait Islander children aged under 6 years, not already known to have, nor being actively managed for, ear and hearing problems.MethodsA 22-person working group comprising Aboriginal and Torres Strait Islander and non-Indigenous members from the primary healthcare, ear, hearing, and research sectors provided guidance of the project. A systematic scoping review addressed research questions relating to primary health ear health and hearing checks for Aboriginal and Torres Strait Islander and other populations at increased risk of persistent ear health problems. Twelve primary studies and eleven guidelines published between 1998 and 2020 were identified and reviewed. Quality and certainty of evidence and risk of bias ratings were completed for studies and guidelines. In the absence of certain and direct evidence, findings and draft recommendations were presented for consensus input to a 79-member expert panel using a modified e-Delphi process. Recommendations were finalised in consultation with working group members and presented to expert panel members for input on considerations relating to implementation.ResultsOverall, the quality, certainty, and directness of evidence in the studies and guidelines reviewed was low. However, the findings provided a basis and structure for the draft recommendations presented during the consensus-building process. After two e-Delphi rounds, seven goals and eight recommendations on the components and timing of Ear Health and Hearing Checks in primary healthcare for young Aboriginal and Torres Strait Islander children were developed.ConclusionsThe systematic scoping review and consensus-building process provided a pragmatic approach for producing strong recommendations within a reasonably short timeframe, despite the low quality and certainty of evidence, and paucity of studies pertaining to primary healthcare settings.

Design of an acoustic direction finding system based on split array frequency domain beamforming algorithm

According to the technical requirement, the principle of the acoustic direction finding and positioning algorithm is introduced, and based on the engineering implementation requirements of split array frequency domain beam forming algorithm, a hardware implementation method based on FPGA +DSP is introduced, which use FPGA to realize the logic control and two pieces of MS320C6678 multi-core DSP to realize the digital beam forming. The hardware system design scheme can realize the program-controlled amplification, filtering, collection, real-time data storage and beam forming processing of the multi-channel acoustic analog signals for acoustic receiving array. At the same time, it can also communicate with the upper computer to achieve upper computer instructions, data transmission, and parameter settings. It has been verified through engineering practice that this scheme has high data processing efficiency and reliable direction finding calculation effect.

Обобщённое неравенство Крамера – Рао в случае совместного пеленгования по азимуту и углу места в условиях сложной электромагнитной обстановки

In this work, a generalized expression is obtained for the Cramer–Rao lower bound in the case of a joint estimation of azimuth and elevation angle in an arbitrary coordinate system in which the vector complex radiation pattern is determined, under conditions of a complex electromagnetic environment, including the presence of noise correlation in spatial channels and differences in its intensity. A theorem is formulated for the Fisher information of joint estimates of azimuth and elevation angle in the case of a multi-channel detector-direction finder with an antenna system described in the selected coordinate system by a vector complex radiation pattern. Dependences of the root-mean-square error of direction finding in azimuth and elevation on the signal-to-noise ratio and true directions to the radio source are obtained, calculated using known and generalized expressions for the Cramer–Rao lower bound. The condition for the applicability of the existing and proposed in the article expression for the Fisher information matrix is obtained. The concept of the “energy” center of the antenna system is given. To confirm the reliability of the obtained generalized expressions for the lower bound of the dispersion of the Cramer–Rao inequality, statistical modeling is carried out. The use of the obtained expressions in practice will allow the most optimal synthesis of antenna devices depending on the structure and characteristics of the direction finder antenna system, the number of antennas and the characteristics of the radio receiving path. Generalized expressions for the lower Cramer–Rao bound are the foundation for organizing the operation of intelligent radio monitoring systems, allowing for a well-founded choice of the optimal antenna array structure that provides the required direction-finding efficiency.

Aerial RIS-Assisted Direction Finding Under Doppler Effect Based on Atomic Norm Minimization

Aerial RIS-Assisted Direction Finding Under Doppler Effect Based on Atomic Norm Minimization

Influence of refracting atmospheric profiles on trace velocity and arrival time

The influence of the atmospheric profile on the trace velocity and arrival time has received little attention, although these properties of sound propagation are important for direction finding and localization. The refracting temperature profile causes the received sound to be delayed or advanced in time compared to that for the temperature at ground height, and the situation is made anisotropic in the presence of wind. We consider refraction by linear temperature and logarithmic wind profiles on the trace velocity and arrival time for distant impulses received at the ground, and use this information in small arrays for direction finding and large arrays for localization.

Determination of the Direction to the Source of Radio Emission in a Radio Direction Finder with a Five-Element Ring Antenna Array and Total Difference Processing

One of the methods for measuring the direction of arrival of an electromagnetic wave from a radio source by an automatic direction finder with a small antenna base and a limited number of channels of the radio receiving path is proposed. The problems that arise during the implementation of this method are listed, and suggestions for their solution are presented. A block diagram has been obtained and a layout of a radio direction finder has been created, in which the processing device is implemented using a two-channel LimeSDR transceiver. The results of the radio direction finder test for detecting and evaluating the direction of an unmanned aerial vehicle are presented.

Comparison of two options for building three-coordinate electronic intelligence stations

The subject–coordinate measurement methods in ground electronic intelligence (ELINT) stations. The goal is to conduct a comparative analysis of two options for the composition ground ELINT stations in terms of accuracy of measuring coordinate information. The tasks to be solved are as follows: assessing the accuracy of determining the coordinates of the time difference of arrival method (TDOAМ) and hybrid method (HM); obtaining analytical ratios for estimating the root-mean-square error (RMSE) of the accuracy of measuring the altitude of radio emission sources (RES) of these methods; on the basis of the obtained estimates and analytical ratios, a comparative analysis of the methods, under conditions where the accuracy of the coordinate information obtained by both methods is commensurate; and development of recommendations regarding the practical application of HM coordinate measurements. The methods used are: the theory of measurements and the theory of evaluation of coordinate information. The following results were obtained: a comparative analysis of the TDOAМ and HM was performed according to the RMSE of the determination of plane coordinates and the altitude of the RES. The accuracy assessment was performed in a known way, based on the linearization of the functional dependence between the measured primary parameters (range differences, elevation angle) and spatial coordinates by expanding in a Taylor series with the deduction of the first two terms of the series. Calculations have shown that the presence of the third side station has very little effect on the accuracy of determining plane coordinates. Significant differences appear only in the results of estimating the RMSE of the RES altitude. To compare the methods, analytical relationships were obtained for estimating the RMSE of the altitude measurement. The condition is determined under which the accuracy of determining the altitude for the HM is not worse than that for the TDOAМ (the accuracy is the same). Starting from this value and further, when using the HM, the altitude is determined more accurately. Conclusions. An HM of high-precision determination of 3 coordinates in ELINT stations, based on measuring two distance differences and direction finding (DF) in the elevation plane, can, with a smaller number of side stations (two instead of three), provide accuracy no worse than the known TDOAM. However, this requires that the RMSE value for DF in elevation should be tenths of degrees. The practical application of HM is possible for the issuance of target designations on air defense missile systems radar.

The prevalence of burnout in oncology professionals: an overview of systematic reviews with meta-analyses including more than 90 distinct studies.

This overview of reviews aimed to summarize the prevalence of burnout and the dimensions of burnout (emotional exhaustion, depersonalization, and personal accomplishment) in oncology professionals around the world. The CINAHL, Embase, PsycINFO, and PubMed databases were searched from inception to September 13, 2023. AMSTAR 2 was used to assess the quality of reviews. The overlap between reviews was calculated. Twelve reviews were included. Overall, reviews showed that burnout was prevalent in oncologists and oncology nurses. On the other hand, no reviews meta-analyzed the prevalence of burnout in oncology radiation therapists. In addition, the dimensions of burnout, high emotional exhaustion, high depersonalization, and low personal accomplishment were highly prevalent across reviews in oncologists, oncology nurses, and oncology radiation therapists. In oncologists, the Americas (specifically Canada) showed the highest prevalence rates for high emotional exhaustion, whereas high depersonalization and low personal accomplishment were mainly prevalent in Europe and Asia, respectively. In oncology nurses, high emotional exhaustion and high depersonalization were mainly prevalent in Asia, whereas low personal accomplishment was more prevalent in the Americas (specifically Canada). The prevalence of overall levels of burnout was not meta-analyzed by continents. Some methodological improvements may help to make more robust the findings of this overview (e.g., specific subgroup meta-analyses by oncology specialties), which may help readers reach more precise, direct, and consistent findings. https://doi.org/10.17605/OSF.IO/QPWG5 .

Modeling of assessment criteria of physical fitness of sports radio direction finders at the stage of specialized basic training

The purpose of the article: to determine the dynamics of constructed mathematical models of indicators of physical fitness of sports radio direction finders at the stage of specialized basic training based on the results of pedagogical control. The methodology of the process of developing evaluation criteria of physical fitness of athletes from radio direction finding is based on the use of mathematical models for analysis, description and forecasting of their parameters. The process of modeling the evaluation criteria of physical fitness included the following stages: definition of the goal and tasks; selection of motor tests; choice of methods; building a model; checking its effectiveness; optimization and correction of the model; terms of use. The scientific novelty consists in the development of means and methods of physical training, the determination of data on the dynamics of the development of general and special motor qualities, the construction of models for evaluating the results of motor testing of young radio direction finders based on regression analysis, which allows modeling the relationship between the dependent variable (Y – evaluation points on the DCOLIFK scale and independent variables (X₁, X₂, ... Xn – quantitative results of motor testing). Assessment of the adequacy of the built models during the pedagogical experiment was carried out according to the coefficient of determination (R2). Conclusion. Constructed models of the dependence of the score on the DCOLIFK scale and the quantitative indicators of motor testing allowed for their interpretation, which includes the consideration of each regression coefficient and the assessment of their influence on the dependent variable, the optimization of the constructed models was carried out in order to determine the influence of each independent variable on Y, forecasting the level physical training based on the results of motor testing.

Concordance of clinical, histopathologic and direct Immunofluorescence findings in patients with intraepidermal immunobullous disorders.

To determine the concordance among clinical, histopathological and immunofluorescence as diagnostic methods for intraepidermal immunobullous disorders. The prospective cross-sectional study was conducted at the Institute of Skin Diseases, Karachi, from December 2020 to December 2022, and comprised adult patients of either gender presenting with complaints of bullae, vesicles, pustules and crusts on the skin or mucous membrane. Diagnostic findings of each patient as obtained by clinical assessment, microscopy and direct immunofluorescence were compared. Data was analysed using SPSS 19. Of the 81 patients, 41(50.6%) were males and 40(49.4%) were females. The overall median age was 35 years (interquartile range: 23 years), with 66(75%) patients aged 19-55 years. The predominant body site involved was the trunk 49(60.5%), followed by mucosa 26(32.1%). Clinical diagnosis detected 80(98.7%) cases, compared to 76(93.8%) by microscopy and 81(100%) by direct immunofluorescence. Direct immunofluorescence was found to be the gold standard for a confirmatory diagnosis of intraepidermal immunobullous disorders, especially when clinical and histopathology findings were inconclusive.

Gridless Underdetermined DOA Estimation for Mobile Agents with Limited Snapshots Based on Deep Convolutional Generative Adversarial Network

Deep learning techniques have made certain breakthroughs in direction-of-arrival (DOA) estimation in recent years. However, most of the current deep-learning-based DOA estimation methods view the direction finding problem as a grid-based multi-label classification task and require multiple samplings with a uniform linear array (ULA), which leads to grid mismatch issues and difficulty in ensuring accurate DOA estimation with insufficient sampling and in underdetermined scenarios. In order to solve these challenges, we propose a new DOA estimation method based on a deep convolutional generative adversarial network (DCGAN) with a coprime array. By employing virtual interpolation, the difference co-array derived from the coprime array is extended to a virtual ULA with more degrees of freedom (DOFs). Then, combining with the Hermitian and Toeplitz prior knowledge, the covariance matrix is retrieved by the DCGAN. A backtracking method is employed to ensure that the reconstructed covariance matrix has a low-rank characteristic. We performed DOA estimation using the MUSIC algorithm. Simulation results demonstrate that the proposed method can not only distinguish more sources than the number of physical sensors but can also quickly and accurately solve DOA, especially with limited snapshots, which is suitable for fast estimation in mobile agent localization.

Direction finding of sources of electromagnetic radiation signals by digital antenna arrays with invariant phase center

Direction finding of sources of electromagnetic radiation signals by digital antenna arrays with invariant phase center

Indirect Effect of Customer Relations on Leadership/Top Management, Employee Relations and Process Management in Examining the Readiness of SMEs to Implement Lean Initiatives

Before deployment of lean initiative, it is of great significance to examine the readiness of manufacturing SMEs to ensure they have the prerequisite for successful implementation. Consequently, in order to determine how prepared Nigerian manufacturing SMEs are to successfully adopt lean initiatives, the study measures the indirect effects of customer relations on leadership/top management, employee relations, and process management. Data for the study was collected from manufacturing SMEs and analyzed using Smart PLS-SEM 4.1. The study's conclusions demonstrate the substantial indirect effects that customer relationships have on employee relations, leadership/top management, and process management. Additionally, a positive correlation between employee relations and leadership/top management and process management is indicated by the direct effect findings. The study reiterates the imperatives of customers at the center of lean philosophy and emphasizes the need for synergy between leadership and employees in effective process management. The study also provides a new insight into the indirect effect of customer relations and the need for top management and employee relations in assessing the manufacturing SMEs' preparedness to implement lean initiatives for the actualization of quality and continuous improvement.

Broadband Direction Finding Based on a Three-Element Time-Modulated Array

Broadband Direction Finding Based on a Three-Element Time-Modulated Array

Spatial Spectrum Direction Finding by Programmable Metasurface With Time Modulation

Spatial Spectrum Direction Finding by Programmable Metasurface With Time Modulation

Research on Direction Finding Method under Impulsive Noise Based on Nonuniform Linear Array

Direction of arrival (DOA) estimation under impulsive noise has always been an important research area in array signal processing. The traditional methods under impulsive noise mostly rely on prior parameters and have high computational complexity. Based on the filtering theory, we present an effective pretreatment filtering technology to cut out the impulse mixed in the array received data and employ the nonuniform linear array to improve the estimation performance further. First, according to the amplitude characteristics of impulse noise, the pretreatment filtering technology is proposed to cut out the impulse based on the median filter and sliding average filter, which is valid for both strong and weak impulsive noise. Second, the minimum redundant array is adopted to carry out array virtual expansion so that the array aperture can be increased and the estimation performance can be improved. Finally, based on the idea of matrix reconstruction, we propose the improved estimation of signal parameters via rotational invariance techniques algorithm and an improved root multiple signal classification algorithm for DOA estimation. Theoretical analysis and simulation results show that the proposed method has a simple processing process, small calculation load, good array expansion ability, and excellent noise adaptability. Moreover, the proposed methods greatly improve the direction-finding performance under the condition of low signal-to-noise ratio and strong impulsive noise.