Frequency Modulation System Research Articles

Analysis of power system frequency and active power based on wind-storage combined frequency modulation system

Abstract To solve the problem of frequency and active power regulation of power systems, this paper proposes a wind-storage combined frequency modulation strategy. The mathematical models of doubly-fed induction machines, pump turbines, and wind turbines are established. Based on wind power frequency modulation, the doubly-fed variable-speed pumped storage unit is added to establish a combined frequency modulation system, and a simulation model on Simulink to analyze the participation of different parts of the combined system in frequency modulation and the active power output of the unit when the load changes. The simulation results show that when the load increases or decreases, the addition of a doubly-fed variable speed pumped storage unit can effectively improve the frequency modulation performance of the system, reduce the fluctuation numbers and amplitude, and reduce the deviation after stabilization. By changing its active power output, a new balance of the system power can be reached, which is conducive to the secure and steady functioning of the power system.

Frequency Regulation Adaptive Control Strategy of Wind Energy Storage System for Wind Speed Uncertainty

In order to reduce the negative influence of wind speed randomness and prediction error on frequency modulation, the reliability of the wind storage system was assessed effectively. In the wind storage frequency modulation system, a state of charge (SOC) adaptive adjustment method for wind speed randomness is proposed. Firstly, through the correlation analysis between the standby capacity of frequency modulation and the output power of wind turbine, the uncertainty of its frequency modulation capacity is revealed. Secondly, in view of the uncertainty of wind turbine frequency modulation, the output power of energy storage frequency modulation is optimized with the goal of minimizing the frequency modulation power deviation of the wind storage front under the framework of model predictive control, and the improved whale optimization algorithm (WOA) is used to solve the problem. Finally, the simulation results show that, under the given 5 min continuous disturbance, the root mean square of frequency regulation of the proposed restoration method is reduced by 56.65% compared to the SOC recovery base point set to 0.5. Under continuous large perturbations, the maximum frequency deviation is reduced by 0.0455 Hz. This effectively shows that this method can not only improve the frequency modulation reliability of wind power system but also improve the continuous frequency modulation capability of energy storage system.

Integrated control strategy of BESS in primary frequency modulation considering SOC recovery

AbstractThis paper proposes a comprehensive control strategy for a battery energy storage system (BESS) participating in primary frequency modulation (FM) while considering the state of charge (SOC) recovery. On the one hand, when the frequency fluctuations are outside the dead zone of the FM, variable coefficient virtual sag control and variable coefficient virtual inertia control are coordinated for more accurate primary FM. Also, an assisted FM strategy is proposed, where the temporal alignment of assisted FM is determined by the regional segmentation of the frequency deviation and SOC, and it enables the BESS to recover SOC concurrently during its involvement in primary FM. On the other hand, when the frequency fluctuations are inside the dead zone of the FM, typical S‐type functions are deployed to dynamically establish the mutual constraints relationships of SOC recovery demand coefficient and frequency deviation. Subsequently, the recovery control coefficients are derived, and accordingly, a SOC recovery strategy is proposed. Finally, simulation results verify the efficacy of the proposed control strategy in the grid primary FM system and demonstrate that the strategy expedites the SOC recovery and concurrently diminishes the conventional unit output.

Analysis of age criteria for provision of the personal frequency-modulated system: An integrative review

RESUMO Objetivo: analisar criticamente se a legislação garantidora do dispositivo Sistema de Frequência Modulada Pessoal abrange a população adequada de escolares com deficiência auditiva no critério idade, de forma a favorecer o desenvolvimento das habilidades necessárias para a comunicação, a alfabetização e a aprendizagem dessas crianças. Métodos: trata-se de uma análise legislativa das normas referentes ao uso do dispositivo Sistema de Frequência Modulada Pessoal. Para a busca da legislação pertinente, foram utilizados bancos de dados públicos, tais como: o portal do Planalto e o portal do Ministério da Saúde. Foram consultadas as leis, portarias e diretrizes Brasileiras no que se refere ao uso do Dispositivo Sistema de Frequência Modulada Pessoal. Revisão da Literatura: foram identificadas na Revisão de Literatura a Portaria n. 1.274 de 25 de junho de 2013, o Relatório do CONITEC sobre o FM no ano de 2020 e a Portaria GM/MS Nº 2.465, de 27 de setembro de 2021 que regulamentam o dispositivo Sistema de Frequência Modulada Pessoal. Conclusão: é evidente que a portaria inicial de 2013, a qual regulamentava o fornecimento do Sistema FM, foi revista e atualizada, uma vez que não contemplava crianças menores de 6 anos, em fase de máxima aprendizagem da linguagem oral, pré-alfabetização e letramento, mesmo que estivessem inseridas em instituições escolares.

A Comparison of Voice Amplifiers and Personal Communication Systems for Hypophonia: An Exploration of Communicative Participation.

The primary purpose of this study was to evaluate how individuals with hypophonia (HP; also referred to as HP participants) and their primary communication partners (PCPs; also referred to as PCP participants) rate communicative participation before and after experience with a speech amplification device. A secondary purpose was to evaluate pre- and post-device effects on self-rated communicative participation for each of the three speech amplification devices trialed outside of the laboratory. Seventeen individuals with HP and their PCPs participated in a crossover design study that compared three different amplification devices: a wired belt-pack amplifier, a wireless stationary amplifier, and a personal frequency modulation (FM) system. Both the individuals with HP and their PCPs self-rated communicative participation at baseline and after trialing each device following 1-week device trial periods at home. Patient-reported outcome measures included the Communicative Effectiveness Survey (CES) and the Voice Activity and Participation Profile (VAPP). Following study completion, participants indicated whether they would like to select a specific device to continue using. Overall, HP participants rated communicative participation following device use higher than that in the pre-device condition, with the FM system resulting in the overall highest VAPP ratings and second highest CES ratings. Furthermore, HP and PCP participants rated these measures similarly. Finally, HP participants who selected a device to continue using self-reported lower total communicative effectiveness scores and greater voice activity limitations and participation restrictions at baseline in comparison to the nonselectors. This study contributes to an increased understanding of how communicative participation is experienced within this clinical population resulting from speech amplification. It is suggested that the inclusion of participation-based outcome measurement is essential to ensure a multidimensional and comprehensive approach to device prescription for individuals with HP.

Resistência ao uso do Sistema FM por crianças e adolescentes: fato ou mito? Uma análise de prontuários de pacientes atendidos em um serviço de saúde auditiva

ABSTRACT Purpose: to compare the use of the Frequency Modulation (FM) System by children and adolescents in a public hearing health center in the state of São Paulo. Methods: the analysis of medical records based on eligibility criteria. Data were collected from 340 participants born between 1998 and 2011, fitted with FM System, and who attended the follow-up appointment after fitting the device. Data were analyzed descriptively and inferentially. Results: hard-of-hearing children and adolescents of both genders from all over Brazil, attending elementary, middle or high school in public or private schools, participated. The data showed that 115 children and 155 adolescents effectively used the device, especially at school. The main difficulty for children was the lack of support from teachers; for adolescents, it was the feeling of embarrassment. Conclusion: some difficulties, especially on children, in adhering to the use of FM Systems were identified. Hence, to ensure the FM System's effective use, the importance of providing guidance and awareness of its benefits to patients, and their family members and teachers, during the fitting appointment and follow-up consultations, is emphasized.

The Effects of Using Hearing Aids and Hearing Assistive Technologies on Programmable Ventriculoperitoneal Shunt.

To investigate interaction between behind-the-ear (BTE) hearing aids, hearing assistive technologies, and programmable shunt valve to understand how use of BTE hearing aids in patients who underwent ventriculoperitoneal shunt (VPS) surgery affects the settings of a programmable shunt valve. In this study, we investigated the magnetic field (MF) generation of 3 BTE hearing aids made by different companies, 1 frequency modulated system using telecoil technology, and 1 wireless microphone technology and their interactions with 2 programmable shunt valves. All measurements were made in a silent booth using 2 different models. The influence of MF strength in the distance modeling was investigated based on the distance from source auditory prostheses. The measurements were recorded using a Gauss meter. In the anatomical modeling, the change in the settings and interaction of the valve in a bust mannequin were investigated. No MF created by BTE hearing aids was detected in the distance modeling. The highest value measured was 32.67 μT (<90 dB noise) when BTE hearing aids and frequency modulated systems were used, and this value decreased as the distance increased. No MF generation was observed at measurements done for distances >10 mm. In the anatomical modeling, the settings of both programmable valves did not change under all acoustic conditions. This is the first study to our knowledge examining the MF created by hearing aids and hearing assistive technologies and its impact on programmable valves and variations in their settings. Our findings showed that it is safe to use BTE hearing aids, frequency modulated systems, and wireless microphone technologies in patients with a programmable VPS.

Using Frequency Modulation System of Hearing-Impaired Students with Integrated Education

Purpose: The purpose of this study was to investigate and analyze the use of the frequency modulation (FM) systems. The degree of speech perception in various school environment and participation in the class using the FM systems for hearing-impaired students and teachers who use the FM systems in integrated education.Methods: Questions were composed of multiple-choice statements that can check for duplicate answers and short-answer for questions developed as a mobile app and implemented by sending individual text messages. The subjects were elementary, middle, and high school eight students receiving integrated education and their eight teachers.Results: The overall opinion of using the FM systems was ‘very satisfied’ for all students, and 75% of teachers showed more satisfaction. FM systems were used in various environments, curriculum activity, experiential learning, practice, group activities, and audiovisual education through media such as TV or computer. The FM system was helpful at any distance in quiet, noisy, or reverberant environments. Using the FM system, the hearing-impaired student felt positive effects when listening to the conversation of the teacher or other friends, but felt negative effects when the teacher and other friends did not understand the speech of the hearing-impaired student.Conclusion: FM systems provided a better classroom acoustic environment for hearing-impaired students. Understanding classroom acoustics such as noise situation, signal-to-noise ratio, and reverberation time expects effective physical integration for the integrated education of hearing-impaired students.

Impact of FM System Use on Acquisition of Phonological Awareness Skills for Children at Risk of Dyslexia: A Preliminary Classroom Study.

This study evaluated the effects of utilizing a frequency modulation (FM) system during phonological awareness intervention for students at risk for dyslexia in a classroom setting. Four first-grade students participated in an adapted-alternating single-case design study. Participants completed intervention targeting two phonological awareness skills and were assigned to wear an FM system during lessons targeting one skill and no FM system during lessons targeting the second skill. Performance was assessed using daily assessments on the skills targeted during intervention and one additional skill. Two participants demonstrated quicker and more pronounced improvement on the skill learned while wearing the FM system. The other two participants did not show improvement on any skill. For children who made gains as a result of phonological awareness intervention, the FM system was associated with quicker and greater improvement. FM systems show promise as a tool to use during phonological awareness training for at least some children at risk for dyslexia. https://doi.org/10.23641/asha.20540139.

A Low-Power and Wide Dynamic Range Digital Pixel Sensor for Intrinsic Optical Imaging in Image-Guided Neurosurgery and Neocortical Epilepsy

Purpose: Determining the borders of brain tumors, seizure foci, and their elimination in patients with brain tumors is very important in preventing cancer recurrence. Multispectral Optical Intrinsic Signal Imaging (MS-OISI) image-guided neurosurgery using visible-Near-Infrared (NIR) wavelengths have shown great potential for image-guided neurosurgery. One of the main challenges is the need for low-power consumption, high-speed and above 100dB dynamic range to capture both visible and NIR photons. The overarching goal of this work is to create a Digital Pixel Sensor (DPS) as a Complementary Metal-Oxide-Semiconductor (CMOS) camera for MS-OISI of the brain in image-guided neurosurgery that has a wide dynamic range, low power consumption, and high speed.&#x0D; Materials and Methods: The general view of neurosurgical system, DPS, and circuit operation of conventional Pulsed Frequency Modulation (PFM) DPS are given first. The proposed PFM DPS and circuit implementation are shown, as well as simulation results obtained using a circuit simulator. Finally, a comparison with other similar works is given.&#x0D; Results: The proposed pixel simulation results show that the performance parameters such as dynamic range and power consumption has improved in comparison to similar works. However, due to its complicated circuitry, it has a low spatial resolution, which can be compensated.&#x0D; Conclusion: The image sensor is post-layout simulated in 0.18μm CMOS technology with a 1.3V supply voltage, resulting in 140dB dynamic range and 7.69μW power dissipation with a 11% fill factor. The key novelty for the proposed PFM DPS is: in-pixel Analog-to-Digital Conversion (ADC), using a low voltage and high-speed dynamic comparator. Furthermore, this work uses a self-reset mechanism, which eliminates the need for an external pulse source, as well as variable reference voltage, which eliminates the necessity for a global constant reference voltage. All of these features demonstrate the excellent potential of the proposed pixel for MS-OISI image-guided neurosurgery.

Perspectives on inclusion of students who are deaf or hard-of-hearing in Armenia

ABSTRACT Perspectives of administrators, educators, parents, and students concerning the educational experiences of students who are deaf or hard-of-hearing (DHH) were examined at two inclusive elementary/middle schools in Yerevan, Armenia. A qualitative study using a case study design was used. There were 33 participants including 15 educators, 6 parents, and 12 students. The students ranged from 9 to 14 years of age. The educators and parents were all typically hearing while 11 of the students were DHH and one was typically hearing. In total, there were 23 interviews and 13 classroom observations. Interviews focused on the following questions: Why is inclusion important? Why is inclusion successful? How can inclusion be improved? Themes emerging from the data included administrative support, frequency modulation (FM) systems, professional development, service delivery, and sign language. Implications are discussed and suggestions are offered to improve inclusion for students who are DHH.

Simulation and Analysis of Frequency Modulation System in MATLAB as Practical Assessment Method for Communication Engineering Course

COVID-19 pandemic hit has raised new challenges for Outcome-Based Education (OBE) system since the normalization of the online education delivery. Still, this era of endemic imposes challenges in satisfying OBE requirements, especially the students’ practical assessments. As an essential part of Communication Engineering, Frequency Modulation (FM) fundamental can be theoretically and mathematically explained during the online classes. However, its practical assessment needs to be done experimentally. Since buying the real devices and tools needed to create a complete FM system consumes high cost, software simulation is the best solution to accommodate the learning processes for all students. Hence, aided by the MATLAB simulation and analysis approaches, this paper presents the implementation of FM practical assessment at Universiti Teknologi MARA (UiTM) as an institute of higher education. For this task, students have built the FM system by using both mathematical and Simulink model. The model also emphasized students on the association between FM’s important parameters: modulating frequency, modulation index, frequency deviation, and bandwidth, with the type of FM, Narrow Band FM (NBFM) or Wide Band FM (WBFM). Results for all model configurations are recorded and analyzed accordingly. From this practical activity, students have demonstrated a better attainment for this course’s Program Outcome (PO) as compared to the conventional assessment methods.

An Efficient Radio Frequency Interference Mitigation Algorithm in Real Synthetic Aperture Radar Data

As a wideband radar system, a synthetic aperture radar (SAR) may conflict with several electromagnetic systems, such as frequency modulation (FM), TV, and other communication systems. These signals, termed as radio frequency interference (RFI), may severely interfere SAR systems from generating a high-resolution image. Numerous previous researches focused on the RFI suppression problem, among which the semiparametric methods have been verified to have the state-of-the-art performance. However, most of the semiparametric methods are computationally expensive and can hardly be used on wide-swath SAR imaging processing. In this article, an efficient semiparametric algorithm is proposed to suppress RFIs via alternating projections. It has comparable performance as the other methods but significantly improves the computational efficiency a lot. It is able to remove both narrowband and wideband RFIs and can be used directly on the Level-1 SAR data. Finally, multiple real SAR data are provided to demonstrate the effectiveness and efficiency of the proposed algorithm.

Frequency Modulation Method and System of Photovoltaic Virtual Synchronous Generator Based on Computer Technology

With people’s attention to environmental protection, clean energy has become an important research and development direction. Among them, photovoltaic power generation has many advantages, such as simple process, no fuel consumption, no noise, no pollution and so on. The power grid capacity is becoming larger and larger, and has a great impact on the environment. Therefore, the grid connection of photovoltaic power generation will cause major problems for the planning, operation and dispatching of power grid. Virtual synchronous generator (hereinafter referred to as VSG) technology can simulate the inertia, primary frequency regulation and voltage regulation characteristics of synchronous generator, which has become an important way to improve the dynamic frequency response ability of the system. Therefore, VSG technology has become an important research technology of photovoltaic grid connected system, among which FM method will also become an important research direction. Firstly, this paper analyzes the VSG algorithm and its basic characteristics. Finally, this paper analyzes the control scheme of overall primary frequency regulation of photovoltaic power station (hereinafter referred to as PPS).

Research on battery SOH estimation algorithm of energy storage frequency modulation system

Based on the experimental data, the life characteristics of lithium-ion battery were analyzed. According to the experimental data statistics, the battery life changes with the number of cycles, the performance of the battery after repeated use is studied, and the changes of battery capacity, discharge efficiency, energy efficiency, internal resistance and other parameters with the battery life are explored. The mathematical model of battery life and battery usage times is established by curve fitting, and the SOH of battery is predicted according to this model. Finally, the SOH of Li ion battery is estimated according to the voltage curve fitting method. Firstly, the battery charging curves under different discharge rates and different SOH are normalized, and the charging voltage error after normalization calculation is compared. According to the existing experimental data, the SOH estimation algorithm of 92Ah lithium-ion battery is verified, the estimation accuracy of voltage curve fitting method is verified, and the estimation results of SOH are analyzed.

Hearing Aid Use in Children With Unilateral Hearing Loss: A Randomized Crossover Clinical Trial.

In children with mild to moderately severe unilateral hearing loss (UHL), assess whether subject-reported quality of life (QOL) and teacher- and parent-reported perception of listening difficulty are affected by use of a hearing aid (HA) with baseline accommodations, compared to children receiving only baseline accommodations. Randomized crossover clinical trial. Thirty-seven children 6-12 years of age with mild to moderately severe UHL and ≥80% word recognition scores in the poorer hearing ear were randomized into arm 1, using baseline accommodations (frequency-modulated system and strategic seating) for 12 weeks, followed by addition of a HA for 12 weeks. The other participants were randomized into the reverse methodology: arm 2, using a HA in addition to baseline accommodations for 12 weeks, followed by baseline accommodations alone. Surveys of QOL (Hearing Environments and Reflection on Quality of Life) and listening difficulties or challenges with hearing amplification (CHILD and LIFE-R questionnaires) were administered at 6-week intervals. Differences in mean survey scores, percent change, and improvement over time were computed between the two arms and inter-arm intervals. Per-protocol analysis was used. Of the 37 children enrolled, 34 children underwent the study interventions and were included in the analysis, (arm 1=20, arm 2=14) (mean [standard deviation] age=8 [1.5] years; 21 boys [61.8%]). Survey scores averaged across both arms during the HA interval (77.79 [15.13]) were significantly higher than during the baseline-only interval (69.67 [14.69], P=.036). There was no significant difference between trial arms in mean scores between the two HA intervals (P=.450) and two baseline-only intervals (P=.539). Hearing-related QOL and listening ability improved in children who met eligibility criteria with mild to moderately severe UHL with HA use compared with baseline accommodations alone. ClinicalTrials.gov identifier: NCT02269124. 1 Laryngoscope, 132:881-888, 2022.

The switch of DNA states filtering the extrinsic noise in the system of frequency modulation

There is a special node, which the large noise of the upstream element may not always lead to a broad distribution of downstream elements. This node is DNA, with upstream element TF and downstream elements mRNA and proteins. By applying the stochastic simulation algorithm (SSA) on gene circuits inspired by the fim operon in Escherichia coli, we found that cells exchanged the distribution of the upstream transcription factor (TF) for the transitional frequency of DNA. Then cells do an inverse transform, which exchanges the transitional frequency of DNA for the distribution of downstream products. Due to this special feature, DNA in the system of frequency modulation is able to reset the noise. By probability generating function, we know the ranges of parameter values that grant such an interesting phenomenon.

Mechanisms for the Clinical Utility of Low-Frequency Stimulation in Neuromodulation of the Dorsal Root Ganglion

Dorsal root ganglion stimulation (DRG-S) involves the electrical modulation of the somata of afferent neural fibers to treat chronic pain. DRG-S has demonstrated clinical efficacy at frequencies lower than typically used with spinal cord stimulation (SCS). In a clinical study, we found that the frequency of DRG-S can be tapered to a frequency as low as 4 Hz with no loss of efficacy. This review discusses possible mechanisms of action underlying effective pain relief with very low-frequency DRG-S. We performed a literature review to explore the role of frequency in neural transmission and the corresponding relevance of frequency settings with neuromodulation. Sensory neural transmission is a frequency-modulated system, with signal frequency determining which mechanisms are activated in the dorsal horn. In the dorsal horn, low-frequency signaling (<20Hz) activates inhibitory processes while higher frequencies (>25Hz) are excitatory. Physiologically, low-threshold mechanoreceptors (LTMRs) fibers transmit or modulate innocuous mechanical touch at frequencies as low as 0.5-5 Hz, while nociceptive fibers transmit pain at high frequencies. We postulate that very low-frequency DRG-S, at least partially, harnesses LTMRs and the native endogenous opioid system. Utilizing lower stimulation frequency decreases the total energy delivery used for DRG-S, extends battery life, and facilitates the development of devices with smaller generators.

MIMO-employed coherent photonic-radar (MIMO-Co-PHRAD) for detection and ranging

Recently, the photonics-radar technology comes out as an attractive candidate in the arena of smart autonomous transportation, surveillance, and navigation-related applications owing to provide wide-spectra to attain improved and precise radar-resolutions. On the other hand, microwave radars, due to limited bandwidth, are incapable of coping with the demands of next-generation radar technology. Moreover, the atmospheric fluctuations become more prominent at higher frequencies and affect the radar’s performance significantly. Subsequently, the authors develop a 2 × 2 multi-input multi-output (MIMO) employed linear frequency-modulated continuous-wave coherent photonic-radar system (MIMO-Co-PHRAD) using OptiSystem™ and MATLAB™ to attain a prolonged detection-range with an enhanced visibility. The developed MIMO-Co-PHRAD is investigated with heterodyne- and homodyne-detection approaches under weak-to-strong regimes of the atmospheric fluctuations like Rain and Fog. A comparison is also drawn for both the demonstrated MIMO-equipped laser-driven coherent photonic-radar systems. The performance of both the developed MIMO-Co-PHRAD systems is evaluated by measuring the intensity of reflected-echoes, signal-to-noise ratio, and range-Doppler patterns. A contrast with the single-input single-output coherent photonic-radar (SISO-Co-PHRAD) is also established to validate the robustness of the demonstrated MIMO-Co-PHRAD.

Time-Varying RFI Mitigation for SAR Systems via Graph Laplacian Clustering Techniques

As a wideband radar system, the synthetic aperture radar (SAR) usually conflicts with several electromagnetic systems, such as frequency modulation (FM), TV, and other communication systems. These signals, which are radio frequency interference (RFI) for radar systems, severely interfere with SAR systems to generate a high-resolution image. Some previous parametric methods focused on the time-varying RFI model; however, they cannot realize the comparable effectiveness and efficiency against semi-parametric methods. However, previous semiparametric methods did not focus on the time-varying RFI case. Hence, in this letter, a graph Laplacian clustering (GLC) semiparametric algorithm is proposed to suppress RFIs by constructing the Laplacian embedding connections between different pulses of signals. As a result, locally time-varying interferences are clustered in a nonlinear low-dimensional manifold and can be effectively mitigated. The real SAR data with measured RFIs are provided to demonstrate the effectiveness and efficiency of the proposed algorithm.