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This letter presents a method for accurately calculating radio frequency (RF) power in a standing wave transmission line system. The proposed approach utilizes two directional couplers in conjunction with a low‐level radio frequency control system. RF power is determined through the application of proposed equations derived from amplitude and phase measurements of coupling signals obtained from the two directional couplers. Experimental validation of the method is conducted using two directional couplers with directivities of 26 and 28 dB, respectively, operating at 162.5 MHz across the entire wavelength. Results indicate that employing a single directional coupler yields average power errors of approximately 6.6% and 5.8%, respectively. However, by implementing the proposed method, the measurement error can be reduced to approximately 1.0%. [ABSTRACT FROM AUTHOR]

This paper presents a composite control algorithm for the radio telescope servo control system to address the target tracking and matched/mismatched disturbance suppression problems. The algorithm consists of the equivalent-input-disturbance (EID) approach and the optimal control method. An EID estimator is developed using the difference between the estimated output of the state observer and the measurement output and then the estimate of the EID is fed forward into the control input to reject the disturbance. A cost function with clear physical meaning is selected and the weighting parameters are adjusted for the optimal controller to improve tracking performance. Considering the nonminimum phase characteristics of the radio telescope system, the state observer gain is computed using the linear matrix inequality (LMI) method. The system stability is analyzed using the small gain theorem, and the linear quadratic regulator (LQR) control method is utilized to determine the state feedback gain. Finally, the composite controller is designed for an identified telescope model. Simulation results show that for the tracking performance, the settling time of proposed method is 1.13 s and reduces by about 0.32 s and 0.87 s than that of the ADRC controller and PI controller, respectively. For the antidisturbance performance, the RMS value and the maximum error of the proposed method are 0.0039 and 0.0128, which are 42.86% and 40.38% of the ADRC controller and 30.71% and 27.77% of the PI controller, respectively, which indicates that the proposed method has better control performance. In addition, the proposed controller has certain robustness to systematic parameter perturbations. [ABSTRACT FROM AUTHOR]

The severity of the 2014–15 West African Ebola epidemic in Liberia was coupled with widespread misunderstanding of the virus among citizens and the proliferation of rumours. Rumour control during outbreaks is imperative to reduce the public's fears about a disease. In Liberia, a tracker system was developed to detect rumours as quickly as possible through SMS (short message service) text messaging. This study focused on assessing rumour circulation in newspapers and on radio and rumour control over time. It relied on a content analysis of SMS messages from the 'DeySay' tracker, print and audio communications of newspapers, and radio programmes, in the time frame between January 2014 and March 2015. The findings show that more rumours appeared in newspapers but were more likely to be overtly characterised as such on the radio. DeySay accurately predicted rumours before they appeared on the radio and in newspapers, supporting its usefulness in future health epidemics. [ABSTRACT FROM AUTHOR]

For many faiths and especially for Muslims, Mecca as well as Kaaba, hold a spiritually important place. Although communication takes place in the form of either human to human or human to the device, however, internet's great future is promised by the internet of things (IoT). Machines as well as computers identify the objects along with metadata recording or using radio waves to control individual targets with the help of a Radiofrequency identification system (RFID), which is an automatic technology. This paper aims to propose an RFID based IoT framework for monitoring pilgrims vital along with health signs by engaging them with slice during Hajj. Facilitation regarding detection as well as monitoring of Personal RFID data of pilgrims is the result of this system. [ABSTRACT FROM AUTHOR]

Summary: The full‐duplex radio transmission technique is a prominent feature in the physical layer of the new IEEE 802.11ax standard for promoting the use of WiFi 6, also called HEW (High‐Efficiency Wireless local area network). Based on this unprecedented technique, a WiFi transmitter has the ability to transmit and receive data simultaneously using the same radio channel, thereby doubling the network capacity and spectral efficiency. However, many challenges related to the MAC (medium access control) layer (including full‐duplex configurations, hidden relationship, unbalance between data streams, and overhead) should be addressed to fully benefit from this technique. The aim of this paper is to design, implement, and assess a new Full‐Duplex MAC protocol by meeting the inherent challenges in controlling full‐duplex radio communications. Accordingly, an efficient and coordinated control protocol is proposed, whose basic principle is to exchange all relevant control information and transmit data without loss or unnecessary delay. The performance evaluation of the proposed protocol demonstrates that the results obtained are the best, especially when the network is dense or the traffic from the access point is heavy. [ABSTRACT FROM AUTHOR]

Summary: Radio spectrum is the backbone for wireless communication. Many recent studies show that most of the available spectrum has already been allocated. Cognitive radio (CR) provides a new dimension in the field of wireless communication and is considered as a life line for the spectrum scarcity problem as seen all around the world nowadays. CR enables the use of dynamic spectrum access, where secondary users (SUs) or unlicensed users are allowed to opportunistically use the spectrum when it is not being used by the primary users (PUs) or licensed users. Medium Access Control (MAC) protocols use the sensing capability and the primary users behavior to generate the transmission opportunities for SUs. This article proposes two Markov based hybrid access methods namely Hybrid‐P1 and Hybrid‐P2, where a secondary user (SU) dynamically decides it's transmission mode between overlay and underlay depending upon the primary users's (PU's) past and present behavior. Analytical results based on the Markov chain concept are very encouraging and verified through OMNeT++ simulator. This work also analyses the performance of overlay only and underlay only methods, which are well known data transmission techniques in the cognitive radio networks (CRNs). Simulation results show the 47% and 59% performance improvement in Hybrid‐P1 access method, when compared to the overlay only and underlay only access methods respectively. Furthermore simulation results also show the 54% and 65% performance improvement in Hybrid‐P2 access method, when compared to the overlay only and underlay only access methods respectively. [ABSTRACT FROM AUTHOR]

Summary: Device‐to‐device (D2D) enables direct communication between Vehicle‐to‐Everything (V2X) devices. For V2X communications, efficient power control and radio sub‐channel allocation schemes are expected to accommodate the growing demand for data traffic of the increasing number of vehicular devices. We propose to investigate the resource allocation problem for V2X networks. We categorize vehicle user equipment (VUEs) into safety and non‐safety VUEs and cellular user equipment (CUEs) into real‐time and non‐real‐time CUEs according to their communication types. The objective of the proposed model is to maximize the total throughput of the system while maintaining quality of service (QoS) for CUEs and VUEs. Chaotic Grey Wolf Optimization (CGWO) algorithm, a meta‐heuristic and evolutionary algorithm, is used to solve the resource allocation problem in V2X communications. Finally, comparisons between the proposed scheme and two other meta‐heuristic algorithms, namely, Particle Swarm Optimization (PSO) and GWO for resource allocation, are carried out. The simulation results prove the effectiveness and performance of the proposed scheme in terms of resource allocation for V2X. They also demonstrate that CGWO‐based resource allocation scheme outperforms both PSO‐based and GWO‐based resource allocation schemes in terms of total achieved throughput. [ABSTRACT FROM AUTHOR]

The control system is the central control unit of the radio telescope. It is used to monitor, control, coordinate, and manage software and hardware systems so as to satisfy the requirements of high-precision control in astronomical observation of radio telescope. The control system architecture is the foundation for the implementation of the control system, which determines the stability, scalability, and maintainability of the control system. Furthermore, the architecture design of the control system is closely geared towards the technological development of radio telescope and computer software architecture. In this article, we analyze the characteristic of the control system of a radio telescope in various steps and discuss the development of their architecture and middleware framework. System architecture and middleware framework of control system also serve as a useful reference for the design of other radio telescope control systems. [ABSTRACT FROM AUTHOR]

Because of the rapid increase of mobile traffic, flexible broadband supportive unmanned aerial vehicle (UAV)‐based 6G mobile networks using free space optical (FSO) links have been recently proposed. Considering the advancements made in UAVs, big data processing, and artificial intelligence precision control technologies, the formation of an additional wireless network based on UAV aerial platforms to assist the existing fixed base stations of the mobile radio access network is considered a highly viable option in the near future. In this paper, a combined time bound optimization scheme is proposed that can adaptively satisfy the control and communication time constraints as well as the processing time constraints in FSO‐based 6G UAV aerial networks. The proposed scheme controls the relation between the number of data flows, input data rate, number of worker nodes considering the time bounds, and the errors that occur during communication and data processing. The simulation results show that the proposed scheme is very effective in satisfying the time constraints for UAV control and radio access network services, even when errors in communication and data processing may occur. [ABSTRACT FROM AUTHOR]

Summary: The ever‐increasing service demand from wireless users under restricted bandwidth necessitates the development of suitable congestion control scheme for throughput maximization. A robust congestion controller design has been addressed in this work to sustain necessary Quality of Service in Cognitive Radio Network. The goal is to reduce packet loss while ensuring optimum utilization of available resources. Sliding mode controller proclaimed for its disturbance rejection capabilities and robustness has been used to design the proposed controller. Using the benefits of sliding mode control, dynamic event‐triggering strategies have been combined for better utilization in resource‐constrained environments. Control execution requires minimal updates while guaranteeing the desired closed‐loop system behavior. The controller efficacy has been validated in simulations. [ABSTRACT FROM AUTHOR]

Purpose: This study incorporates a gradient system imperfection model into an optimal control framework for radio frequency (RF) pulse design. Theory and Methods: The joint design of minimum‐time RF and slice selective gradient shapes is posed as an optimal control problem. Hardware limitations such as maximal amplitudes for RF and slice selective gradient or its slew rate are included as hard constraints to assure practical applicability of the optimized waveforms. In order to guarantee the performance of the optimized waveform with possible gradient system disturbances such as limited system bandwidth and eddy currents, a measured gradient impulse response function (GIRF) for a specific system is integrated into the optimization. Results: The method generates optimized RF and pre‐distorted slice selective gradient shapes for refocusing that are able to fully compensate the modeled imperfections of the gradient system under investigation. The results nearly regenerate the optimal results of an idealized gradient system. The numerical Bloch simulations are validated by phantom and in‐vivo experiments on 2 3T scanners. Conclusions: The presented design approach demonstrates the successful correction of gradient system imperfections within an optimal control framework for RF pulse design. [ABSTRACT FROM AUTHOR]

This paper presents a novel low-power CMOS extra low-frequency (ELF) waveform generator based on an operational trans-conductance amplifier (OTA). The generator has been designed and fabricated using 2.5-V devices available in 130-nm IBM CMOS technology with a ±1.2-V voltage supply. Using the same topology, two sets of device dimensions and circuit components are designed and fabricated for comparing relative performance, silicon area and power dissipation. The first design consumes 691 μW, while the second design consumes 943 μW using the same voltage supply. This low-power performance enables the circuit to be used in many micro-power applications. ELF oscillation is achieved for the two designs being around 3.95 Hz and 3.90 Hz, respectively, with negligible waveform distortion. The measured frequencies agree well with the simulation results. The first design is found to provide overall optimal performance compared to the second design at the expense of higher silicon area. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper focused on discrete movements of hand in reaching actions, which necessarily occur during machine operation. The relationship between the performance of a console operation and the operator's reaching actions was investigated by applying Fitts' law and by examining a state transition of the operation. A remote operation experimental system was built using two radio controlled construction equipments, and the operator training process was analyzed empirically with those methods. The results showed the covariance of the fitting error to Fitts' law decreased as the operators' skill improved, although the fitting itself to the law was not sufficiently good. And it was confirmed that the covariance of difficulty index of the reaching action increased. These facts indicated that skill level of the discrete motion during operation can be estimated by investigating two types of the covariance. [ABSTRACT FROM AUTHOR]

A 28.2 GHz (K-band) low-noise amplifier (LNA) using standard 0.18-μm CMOS technology was designed and implemented. To achieve sufficient gain, this LNA was composed of three cascaded common-source stages, and a peaking inductor (Lg3) was added in the input terminal of the third stage to boost the peak gain (S21) of 34.9% (simulation). Shunt RC feedback was adopted in the second and the third stage, respectively, for achieving good input and output impedance matching. At 28.2 GHz, this LNA achieved input return loss (S11) of -13.4 dB, output return loss (S22) of -20.5 dB, forward gain (S21) of 12.9 dB, reverse isolation (S12) of -50.2 dB, noise figure of 6.07 dB and input-referred 1-dB compression point (P1dB-in) of -10.8 dBm. The minimum noise figure was 5.75 dB at 28.8 GHz. The chip area was only 950 μm × 590 μm excluding the test pads. The power consumption was 30.56 mW from a 1.8-V power supply. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1148–1152, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23332 [ABSTRACT FROM AUTHOR]

This paper proposes a turnover-free control method for a teleoperated mobile agent (or vehicle) moving through uneven terrain. The teleoperated agent is primarily driven by an operator at a remote site and is able to react autonomously when a possible turnover is predicted. In order to predict the turnover, a low-cost terrain prediction sensor has been developed using a camera vision with a structured laser light. Since it is difficult for an operator to predict the reactive motion of the agent, a force reflection technique with a force feedback joystick is employed to intuitively recognize the inconsistency between the intended motion and the reactive motion of the agent. Finally, to verify the feasibility and effectiveness of the proposed method, experiments with the ROBHAZ-DT (actual mobile agent) have been carried out. In the experiments, the operator could recognize the reactive motion of the agent for turnover prevention through force reflection while the agent was moving on slopped terrain. © 2006 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Recently, the use of radio-controlled cranes in Finnish manufacturing industry has increased considerably. This development has resulted in the diversification of tasks, more effective use of cranes, and sometimes also the improvement of working conditions. The aim of this study was to investigate safety effects of radio control and to identify the conditions where the use of radio-controlled cranes is functional and, on the other hand, problematic. Data regarding experience in the use of radio-controlled cranes in Finnish industry were collected with a questionnaire. A total of 70 manufacturing enterprises responded: they had a total of 252 cranes equipped with a radio-control system. Data on cranes and their use, radio-control devices, safety, and the properties of radio- control systems were analyzed. The safety inspectors' observations on defects in the implementation of radio-controlled cranes gave additional information about factors to be considered in the evaluation of hazards. Ergonomic properties of the control devices were also studied. [ABSTRACT FROM AUTHOR]

A radiotelemetry stimulator for the conditioning of large animals by the application of high voltage, short duration pulses to the skin surface is described. The system uses commercial radio control assemblies to simplify construction. [ABSTRACT FROM AUTHOR]

The integration of data privacy and security into radio frequency identification (RFID) technology, particularly into RFID tags, has become one of the most attractive research areas. A crucial challenge in RFID technology research lies in providing an efficient protection for systems against information theft and illegitimate access. This article proposes a secure solution based on an RFID card for physical biometric access‐control applications. This is done by integrating two biometric modalities, namely face and fingerprint which are secured via a double watermarking technique. The suggested approach is ensured by two levels of watermarking. At the first level, the wavelet packet decomposition watermarking algorithm is used to insert features from the fingerprint (minutiae) in the face image of an authorized person. At the second level, the same watermarking algorithm is employed to insert the fingerprint watermark in the face features extracted by Gabor filters from the previously watermarked face image (at the first level). The obtained secured watermarked biometric data are then integrated in a 1‐kB high frequency proximity RFID card. This combination of both RFID technology and the double watermarking technique provides a biometric control access framework. Compared with the state‐of‐the‐art frameworks, the proposed one ensures a good compromise between a reduced computational complexity and a high level of data security while maintaining a small space of storage and a low cost compared to those of the marketed products. [ABSTRACT FROM AUTHOR]