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In this paper, we investigate group decision making problems based on interval fuzzy preference relations. We define an uncertain power weighted average (UPWA) operator and an uncertain power ordered weighted average (UPOWA) operator, on the basis of the power average operator of Yager (IEEE Trans Syst Man Cybern A 31:724–731, 1988) and the uncertain geometric mean. In the situations where the weights of experts are known, we develop a method based on the UPWA operator for group decision making with interval fuzzy preference relations; and in the situations where the weights of experts are unknown, we develop a method based on the UPOWA operator for group decision making with interval fuzzy preference relations.

Logging while drilling is to transmit down‐hole measurement data to the surface timely and accurately to ensure the normal production. Drilling data transmission system includes mud pulse and electromagnetic wave. The transmission rate of these methods is only tens of bits per second. To solve the problems of slow transmission rate, low accuracy and long waiting time for drilling data, an acoustic wireless communication system based on orthogonal frequency division multiplexing (OFDM) is developed. The hardware and software design of the acoustic wireless communication system has been completed, and experiments have been carried out. The communication channel is drilling fluid, a frequency selective fading channel with Gaussian white noise and obvious multipath effect. OFDM can be used to solve the adverse effects of these problems on signal transmission. Schmidl–Cox algorithm is used for signal synchronization. Error control coding adopts CRC32 algorithm. The experimental results show that the transmission rate of BPSK mapped OFDM signal can reach 250 kbit/s when the bit error rate is 10−3. Compared with the traditional wireless communication system, an acoustic wireless communication system based on drilling fluid has the advantages of high data transmission rate, low bit error rate and strong anti‐multi‐path fading ability. Low data transmission rate, long waiting time and other problems seriously restrict the oil production efficiency and output. In order to solve the above problems, we developed a drilling data acoustic wireless communication system based on OFDM. Compared with traditional method, acoustic wireless communication system has advantages of high data transmission rate, low bit error rate and strong anti‐multi‐path fading ability.

Orthogonal frequency division multiplexing (OFDM) is a famous multi-carrier modulation technique as it has a vast range of features like robustness against multi-path fading, higher bandwidth efficiency, and higher data rates. Though, OFDM has its own challenges. Among them, high peak power to average power ratio (PAPR) of the transmitted signal is the major problem in OFDM. In recent years, deep learning has drastically enhanced the performance of PAPR. In addition, the excessive training data and high computational complexity lead to a considerable issue in OFDM system. Thus, this paper implements a new PAPR reduction scheme in OFDM Systems through hybrid deep learning algorithms. A new optimized hybrid deep learning termed O-DNN + RNN is implemented by integrating the deep neural networks (DNN) and recurrent neural networks (RNN), where the parameters of both DNN and RNN are optimized using Hybrid Reptile Dragonfly Search Algorithm (HR-DSA). The new deep learning model is adopted for determining the constellation mapping and demapping of symbols on each subcarrier. This new optimized hybrid deep learning helps in reducing the PAPR and maximizes the performance.

The FLASHForward experimental facility is a high-performance test-bed for precision plasma wakefield research, aiming to accelerate high-quality electron beams to GeV-levels in a few centimetres of ionized gas. The plasma is created by ionizing gas in a gas cell either by a high-voltage discharge or a high-intensity laser pulse. The electrons to be accelerated will either be injected internally from the plasma background or externally from the FLASH superconducting RF front end. In both cases, the wakefield will be driven by electron beams provided by the FLASH gun and linac modules operating with a 10 Hz macro-pulse structure, generating 1.25 GeV, 1 nC electron bunches at up to 3 MHz micro-pulse repetition rates. At full capacity, this FLASH bunch-train structure corresponds to 30 kW of average power, orders of magnitude higher than drivers available to other state-of-the-art LWFA and PWFA experiments. This high-power functionality means FLASHForward is the only plasma wakefield facility in the world with the immediate capability to develop, explore and benchmark high-average-power plasma wakefield research essential for next-generation facilities. The operational parameters and technical highlights of the experiment are discussed, as well as the scientific goals and high-average-power outlook. This article is part of the Theo Murphy meeting issue ‘Directions in particle beam-driven plasma wakefield acceleration’.

In this paper, a hybrid approach using clipping and companding techniques is introduced to reduce the peak to average power ratio (PAPR) of orthogonal frequency division multiplexing based differential chaos shift keying (OFDM-DCSK), which is the major drawback of the OFDM-DCSK. The hybrid function is processed at the end of the transmitter before transmitting the signal. However, there is no need for an inverse function at the receiver, which decreases the system complexity. Several techniques have been proposed in the literature for decreasing the PAPR value. Clipping and companding are active methods in terms of reducing the PAPR. Finally, the PAPR reduction and bit error rate (BER) performances are evaluated. The simulation results show that this technique gives better performance as compared with the clipping and companding techniques.

Using cryogenic laser technology, it is now possible to design and demonstrate lasers that have concomitant high average and peak powers, with near-diffraction-limited beam quality. We refer to these new laser systems as HAPP lasers. In this paper, we review important laser crystal materials properties at cryogenic temperature, with an emphasis on Yb lasers, and discuss the important design considerations, including the laser-induced damage threshold, nonlinear effects and thermal effects. A comprehensive model is presented to describe diode pulsed pumping with arbitrary duration and repetition rate, and is used with the Frantz–Nodvik equation to describe, to first order, the performance of HAPP laser systems. A computer code with representative results is also described.

The development of the Internet of Things (IoT) and artificial intelligence has accompanied the evolution of energy demand and structure in the new era, and the power sources for billions of distributed electronics and sensors have aroused worldwide interest. As an alternative energy harvesting technology, triboelectric nanogenerators (TENGs) have received remarkable attention and have shown attractive potential applications for use in micro/nano power sources, self-powered sensors, high-voltage power sources, and blue energy due to their advantages of small size, light weight, flexibility, low cost, and high efficiency at low frequency. In this review, we discuss high-performance TENGs from the perspectives of triboelectric charge density, output voltage, energy density, and corresponding quantification methods. Among these topics, the limitations, optimization methods and techniques, and potential directions to challenge these limits are comprehensively discussed and reviewed. Finally, we discuss the emerging challenges, strategies, and opportunities for research and development of highperformance TENGs.

Nowadays, the demand for communication multi-carriers’ channels, where the sub-channels are made mutually independent by using orthogonal frequency division multiplexing (OFDM), is widespread both for wireless and wired communication systems. Even if OFDM is a spectrally efficient modulation scheme, due to the allowed number of subcarriers, high data rate, and good coverage, the transmitted signal can present high peak values in the time domain, due to inverse fast Fourier transform operations. This gives rise to high peak-to-average power ratio (PAPR) with respect to single carrier systems. These peaks can saturate the transmitting amplifiers, modifying the shape of the OFDM symbol and affecting its information content, and they give rise to electromagnetic compatibility issues for the surrounding electric devices. In this paper, a closed form PAPR reduction algorithm is proposed, which belongs to selected mapping (SLM) methods. These methods consist in shifting the phases of the components to minimize the amplitude of the peaks. The determination of the optimal set of phase shifts is a very complex problem; therefore, the SLM approaches proposed in literature all resort to iterative algorithms. Moreover, as this calculation must be performed online, both the computational cost and the effect on the bit rate (BR) cannot be established a priori. The proposed analytic algorithm finds the optimal phase shifts of an approximated formulation of the PAPR. Simulation results outperform unprocessed conventional OFDM transmission by several dBs. Moreover, the complementary cumulative distribution function (CCDF) shows that, in most of the packets, the proposed algorithm reduces the PAPR if compared with randomly selected phase shifts. For example, with a number of shifted phases U=8, the CCFD curves corresponding to the analytical and random methods intersect at a probability value equal to 10−2, which means that in 99% of cases the former method reduces the PAPR more than the latter one. This is also confirmed by the value of the gain, which, at the same number of shifted phases and at the probability value equal to 10−1, changes from 2.09 dB for the analytical to 1.68 dB for the random SLM.

High peak-to-average power ratio (PAPR) in modern modulation schemes causes power amplifier nonlinearity due to transistor saturation and results in considerable power loss. To mitigate these effects and extend the linear range, this work proposes a novel harmonic injection technique aimed at enhancing the 1-dB compression point. A new analytical model based on Taylor series expansion and drain current derivatives is developed, enabling a fully integrated injection scheme that avoids conventional components such as circulators or frequency doublers. A new biasing method is also derived from this model. To address power loss under high PAPR, a new fully CMOS-integrated hybrid envelope-tracking modulator is introduced. A custom-designed sensing circuit removes the need for sensing resistors and external voltage references, significantly reducing output ripple. Moreover, a new current management scheme is introduced that removes the ripple-filtering burden from the linear amplifier, simplifying its design. A comprehensive mathematical analysis is also provided to characterize the trade-offs between the inductor value and switching frequency, enabling a fully integrated on-chip inductor solution. Results in 180 nm CMOS show improvements of 1.2 dB in output saturation power, 4.4 dB in P 1dB , and 12.5% in peak PAE. PAE at P 1dB improves by 14.6%, with EVM remaining below 5%.

Several high-speed wireless systems use Orthogonal Frequency Division Multiplexing (OFDM) due to its advantages. 5G has adopted OFDM and is expected to be considered beyond 5G (B5G). Meanwhile, OFDM has a high Peak-to-Average Power Ratio (PAPR) problem. Hybridization between two PAPR reduction techniques gains the two techniques’ advantages. Hybrid precoding-companding techniques are attractive as they require small computational complexity to achieve high PAPR reduction gain. Many precoding-companding techniques were introduced to increasing the PAPR reduction gain. However, reducing Bit Error Rate (BER) and out-of-band (OOB) radiation are more significant than increasing PAPR reduction gain. This paper proposes a new precoding-companding technique to better reduce the BER and OOB radiation than previous precoding-companding techniques. Results showed that the proposed technique outperforms all previous precoding-companding techniques in BER enhancement and OOB radiation reduction. The proposed technique reduces the Error Vector Magnitude (EVM) by 15 dB compared with 10 dB for the best previous technique. Additionally, the proposed technique increases high power amplifier efficiency (HPA) by 11.4%, while the best previous technique increased HPA efficiency by 9.8%. Moreover, our proposal achieves PAPR reduction gain better than the most known powerful PAPR reduction technique with a 99% reduction in required computational complexity.