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Tower cranes with slender jib transporting bulky loads are commonly applied in the construction site. Human-operated commands induce vibrations of the cantilever jib, swing, and twisting of the suspended load. Coupled oscillations among jib deflection, load swing and load twisting exhibit complex dynamic behavior. Furthermore, coupled-system frequencies significantly differ from uncoupled frequencies of the jib and pendulum. Unfortunately, little attention has been directed at the coupled-oscillation dynamics and control of jib deflection, load swing, and load twisting. A dynamic model of a tower crane slewing a slender jib and moving a distributed-mass load is derived. The fully coupled effects among jib deflection, load swing, and load twisting are described in the model. Then, an equation for predicting coupled-system frequencies is presented from the analytical model. Meanwhile, a hybrid piecewise smoother is proposed to filter out coupled oscillations among jib deflection, load swing and load twisting. Many experiments validate the utility of frequency-estimation equation and verify the success of the smoother. [ABSTRACT FROM AUTHOR]

In this article, the experimental investigations on a 263-GHz gyrotron are presented. With the change of the operating magnetic field and the beam energy, the operating frequency is adjusted and the output power is also varied. It is found that when the operating magnetic field changes from 9.59 to 9.82 T at a fixed operating voltage of 20 kV and a beam current of 0.8 A, the operating frequency increases from 263.39 to 264.84 GHz, the frequency-tuning range is about 1.45 GHz, and the output power is from 26 to 463 W. When the operating voltage increases from 14.4 to 22.2 kV at a fixed operating magnetic field of 9.65 T, the operating frequency decreases from 263.68 to 263.40 GHz, the frequency-tuning range is 0.28 GHz, and the output power changes from 52 to 424 W. When the operating magnetic field is fixed at 9.65 T and the operating voltage is fixed at 20 kV, but the beam current increases from 120 to 880 mA, the output power increases from 21 to 277 W, the operating frequency increases from 263.396 to 263.425 GHz, and the frequency-tunable range is 0.029 GHz. The effects of the axial position of the gyrotron in the superconducting magnet system on the operating frequency, the frequency-tuning range, and the output power are also investigated experimentally. When the beam current is increased, the nonstationary phenomenon is observed. [ABSTRACT FROM AUTHOR]

Personality analysis is widely used in occupational aptitude tests and entrance psychological tests. However, answering hundreds of questions at once seems to be a burden. Inspired by personality psychology, we propose a multimodal attention network with Category-based mean square error (CBMSE) for personality assessment. With this method, we can obtain information about one’s behaviour from his or her daily videos, including his or her gaze distribution, speech features, and facial expression changes, to accurately determine personality traits. In particular, we propose a new approach to implementing an attention mechanism based on the facial Region of No Interest (RoNI), which can achieve higher accuracy and reduce the number of network parameters. Simultaneously, we use CBMSE, a loss function with a higher penalty for the fuzzy boundary in personality assessment, to help the network distinguish boundary data. After effective data fusion, this method achieves an average prediction accuracy of 92.07%, which is higher than any other state-of-the-art model on the dataset of the ChaLearn Looking at People challenge in association with ECCV 2016. [ABSTRACT FROM AUTHOR]

This communication presents an omnidirectional rectenna array with an enhanced RF power distributing strategy. The proposed rectenna array consists of three bidirectional subarray antennas, a $3\times $ 3 RF power distributing network, and a three-element rectifier array. Utilizing the $3\times $ 3 network to redistribute the varying RF power received by the three antennas, the RF-to-dc power conversion efficiency of the rectenna array can be enhanced under the illumination of electromagnetic (EM) waves with arbitrary incident angles. Measurement results reveal that the proposed rectenna array has an improved omnidirectional-harvesting capability compared with the design without RF power distributing strategy, thus can be readily used for RF energy-harvesting applications. [ABSTRACT FROM AUTHOR]

As a terahertz (THz) radiation source, the frequency-tunable gyrotron is promising in application and attractive to researchers. In this article, the nonstationary phenomenon in a frequency-tunable gyrotron operating in different regimes—gyromonotron, transition, and gyro-backward-wave oscillator (BWO)—has been investigated in detail by 3-D particle in cell (PIC) simulation. Simulated results demonstrate that among the three regimes, gyromonotron has the strongest capability to keep stationary, and nonstationary oscillations are most likely to occur in the transition regime. Moreover, in the gyro-BWO regime, the capability of the system to maintain steady-state operation gets slightly improved with the increase in the axial mode. The corresponding interpretation is based on detuning frequency and feedback mechanism. Finally, the effect of the velocity spread on the nonstationary behavior has also been studied. Investigations reveal that the stability of stationary oscillations would be weakened when velocity spread is considered. The results in this article may be of benefit of a deeper insight into the nonstationary phenomenon in a frequency-tunable gyrotron. [ABSTRACT FROM AUTHOR]

Sparse unmixing is an important technique for analyzing and processing hyperspectral images (HSIs). Simultaneously exploiting spatial correlation and sparsity improves substantially abundance estimation accuracy. In this article, we propose to exploit nonlocal spatial information in the HSI for the sparse unmixing problem. Specifically, we first group similar patches in the HSI, and then unmix each group by imposing simultaneous a low-rank constraint and joint sparsity in the corresponding third-order abundance tensor. To this end, we build an unmixing model with a mixed regularization term consisting of the sum of the weighted tensor trace norm and the weighted tensor $\ell _{2,1}$ -norm of the abundance tensor. The proposed model is solved under the alternating direction method of multipliers framework. We term the developed algorithm as the nonlocal tensor-based sparse unmixing algorithm. The effectiveness of the proposed algorithm is illustrated in experiments with both simulated and real hyperspectral data sets. [ABSTRACT FROM AUTHOR]

Motion-induced unwanted cable swing and liquid sloshing degrade the effectiveness and safety of suspended liquid container. The manipulations of cable-suspended liquid container become more challenging due to the coupled pendulum-sloshing dynamics. This article develops the dynamic modeling of cable-suspended liquid container with coupled pendulum-sloshing dynamics. Afterward, a novel control method is proposed for controlling the coupled pendulum-sloshing dynamics. Numerous simulated and experimental results obtained from a small-scale industrial crane carrying a liquid container validated the dynamic behavior of the nonlinear model and demonstrated the effectiveness of the control method. [ABSTRACT FROM AUTHOR]

Frequency-tunable gyrotron is a promising terahertz (THz) radiation source for many modern applications. Actually, a resonator-based gyrotron oscillator can play dual functions: gyromonotron and reflected-type gyro-backward-wave oscillator (BWO) corresponding to the forward-wave and backward-wave operation. The performances of the gyromonotron and the reflected-type gyro-BWO for a 0.5-THz frequency-tunable gyrotron have been theoretically investigated in detail. The calculated results indicate that the frequency tunability, the field profile of the axial mode, and the beam–wave interaction efficiency of the gyromonotron and the reflected-type gyro-BWO are dramatically different from each other. The gyromonotron state can switch to the reflected-type gyro-BWO state by means of increasing the operating magnetic field. In addition, we have systematically investigated the characteristics of the 0.5-THz frequency-tunable gyrotron with different beam–wave interaction structures, especially for the reflected-type gyro-BWO. It is found that the tapered angle of the output section has a significant effect on the frequency tunability of the reflected-type gyro-BWO, and the multisection cavity can improve the performance of the reflected-type gyro-BWO. The results of this study may be beneficial for getting a deeper insight into the physics of the forward-wave and backward-wave operation of a frequency-tunable gyrotron. [ABSTRACT FROM AUTHOR]

In this paper, we further consider the leader-following attitude consensus problem of multiple rigid body systems subject to jointly connected switching networks by a distributed attitude feedback control law. Since the network is switching, the closed-loop system is discontinuous. We overcome this difficulty by a generalized Barbalat's lemma. Moreover, we remove two restrictive assumptions in the literature. As a result, our control law is fully distributed and the result is global. [ABSTRACT FROM AUTHOR]

Continuously frequency-tunable terahertz (THz) gyrotrons are attractive for modern applications. Nevertheless, it is challenging to generate a broadband, continuously frequency-tunable range for a single-mode operation gyrotron. In this article, a frequency-tuning scheme based on multimode switching and axial mode transition is employed to effectively enhance the frequency-tunable capacity of a THz gyrotron. A 0.5-THz broadband, continuously frequency-tunable gyrotron with four operating modes TE $_{5,7,q}$ , TE $_{10,5,q}$ , TE $_{3,8,q}$ , and TE $_{1,9,q}$ ($q = 1, 2, 3\ldots $) working successively has been theoretically investigated in detail and the principle of the operating mechanism is proposed in this article. By means of changing the operating magnetic field and the beam energy, the four operating modes are excited successively. Numerically calculated results show that a 10-GHz level continuous frequency tuning range is obtainable. The frequency can be tuned from 500.3 to 510.8 GHz successively. Meanwhile, the output power always remains at hundreds of watts level, which is typically favorable for modern applications. Besides, the corresponding magnetron injection gun (MIG) is optimized to meet the requirements of the broadband frequency-tunable gyrotron. The electron beam quality versus the operating voltage or the operating magnetic field has also been studied. The principle could benefit the development of broadband, frequency-tunable THz gyrotrons. [ABSTRACT FROM AUTHOR]

In this paper, we study the adaptive fuzzy formation control of multiple autonomous agents with prioritized missions. For a platoon of autonomous agents in an unknown environment containing multiple obstacles, formation control is investigated, where each agent is modeled by a second-order nonlinear system under unknown external disturbance in the Brunovsky form. We introduce the systematic procedure of null-space-based projection to convert the prioritized multimission control problem into a behavioral control problem. Then, we further develop a class of nonlinear-fast-terminal-sliding-mode-based adaptive control strategies that combine the fuzzy logic systems by jointly considering both kinematic and dynamic levels of the agents. The proposed controllers can guarantee each individual agent to achieve the predesigned desired pattern and drive the entire systems to achieve the prescribed missions. A simulation example with five agents demonstrates the effectiveness of the algorithm. Finally, the strategies are experimentally validated using a platoon of Pioneer 3AT and 3DX mobile robots. [ABSTRACT FROM AUTHOR]

Sign language recognition (SLR) is an important and challenging research topic in the multimedia field. Conventional techniques for SLR rely on hand-crafted features, which achieve limited success. In this paper, we present attention-based 3D-convolutional neural networks (3D-CNNs) for SLR. The framework has two advantages: 3D-CNNs learn spatio-temporal features from raw video without prior knowledge and the attention mechanism helps to select the clue. When training 3D-CNN for capturing spatio-temporal features, spatial attention is incorporated into the network to focus on the areas of interest. After feature extraction, temporal attention is utilized to select the significant motions for classification. The proposed method is evaluated on two large scale sign language data sets. The first one, collected by ourselves, is a Chinese sign language data set that consists of 500 categories. The other is the ChaLearn14 benchmark. The experiment results demonstrate the effectiveness of our approach compared with state-of-the-art algorithms. [ABSTRACT FROM AUTHOR]

Hyperspectral unmixing has attracted much attention in recent years. Single sparse unmixing assumes that a pixel in a hyperspectral image consists of a relatively small number of spectral signatures from large, ever-growing, and available spectral libraries. Joint-sparsity (or row-sparsity) model typically enforces all pixels in a neighborhood to share the same set of spectral signatures. The two sparse models are widely used in the literature. In this paper, we propose a joint-sparsity-blocks model for abundance estimation problem. Namely, the abundance matrix of size $m\times n$ is partitioned to have one row block and $s$ column blocks and each column block itself is joint-sparse. It generalizes both the single (i.e., $s=n$) and the joint (i.e., $s=1$) sparsities. Moreover, concatenating the proposed joint-sparsity-blocks structure and low rankness assumption on the abundance coefficients, we develop a new algorithm called joint-sparse-blocks and low-rank unmixing. In particular, for the joint-sparse-blocks regression problem, we develop a two-level reweighting strategy to enhance the sparsity along the rows within each block. Simulated and real-data experiments demonstrate the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Millimeter wave (mmWave) communication is a key technology for fifth generation (5G) wireless communication systems due to its tremendous bandwidth available to support high data rate transmission. This article investigates the recent developments and future challenges in 5G mmWave channel sounders, measurements, and models. Various channel sounders are comprehensively classified and compared. Channel measurements in diverse indoor and outdoor scenarios for different mmWave bands are surveyed. Meanwhile, a comparison of multiple mmWave bands, validation of mmWave massive multiple-input multiple-output (MIMO) channel properties, and measurement and modeling of human blockage effects are shown. Different channel modeling approaches including deterministic, semi-deterministic, and stochastic modeling methods are summarized. Some future research directions are also given. [ABSTRACT FROM AUTHOR]

Different contents of silicon carbide (SiC) nanowires were mixed with Poly(vinylidene fluoride) (PVDF) to facilitate the polar phase crystallization. It was shown that the annealing temperature and SiC content affected on the phase and crystalline structures of PVDF/SiC samples. Furthermore, the addition of SiC nanowire enhanced the transformation of non-polar α phase to polar phases and increased the relative fraction of β phase in PVDF. Due to the nucleating agent mechanism of SiC nanowires, the ion-dipole interaction between the negatively charged surface of SiC nanowires and the positive CH2 groups in PVDF facilitated the formation of polar phases in PVDF. [ABSTRACT FROM AUTHOR]

This paper reports a high-sensitivity resonant electrometer based on the mode localization of two degree-of-freedom weakly coupled resonators (WCRs). When charges are applied to the input electrodes, the effective stiffness of a specific resonator of the WCRs will be perturbed, leading to a drastic change in mode shape owing to the mode localization phenomenon. By measuring the shift of the amplitude ratio, the small charge fluctuation can be accurately sensed. The theoretical mode of the electrometer is established based on the transfer functions of the WCRs. In particular, we establish the design rules of the coupling factor according to the −3-dB bandwidth, amplitude ratio measurement errors, and frequency misalignment between the resonators. The experimental results show that the amplitude ratio-based sensitivity is $\sim 2151$ times higher than the frequency-based sensitivity. The amplitude ratio-based resolution of the electrometer is approximately 1.269 fC. [2016-0119] [ABSTRACT FROM AUTHOR]

Uniform leaky-wave antennas (LWAs) with limited length have suffered from the presence of high-level side lobes, which could lead to the reception of unwanted noise especially when the LWA is short. This communication examines how the phase constant of a short LWA can be manipulated to achieve side lobe suppression. The tapering of the phase constant is shown to result in higher order “image patterns,” which can be used advantageously for side lobe suppression. Validation of this principle is given by a cosine-shaped width-tapering profile design of a half-mode substrate-integrated waveguide (HMSIW) LWA. The measured results show that the side lobe level (SLL) of a short ($1.4 \lambda _0$) HMSIW LWA has been suppressed to below -16\;\dB in the entire space wave leakage region using this tapering profile. [ABSTRACT FROM PUBLISHER]

While significant work has been directed at suppressing the 2-D slosh, less success has been achieved with reducing the 3-D slosh in a moving rectangular container. Control of the 3-D slosh in a moving rectangular liquid container is very challenging because there are two fundamental modes and an infinite number of high modes. The dynamics of the 3-D slosh in a moving rectangular container are derived. The theoretic analysis shows that both the two fundamental and high modes have large impacts on the sloshing dynamics. A command smoothing technique is designed to suppress slosh for the two fundamental and high modes. Comparing with the combined input shaper and the low-pass filter scheme, the presented smoother provides more robustness to variations in the sloshing frequency. Simulations over a large range of various working conditions and system parameters are conducted to analyze the liquid sloshing dynamics and the robustness of the method. Experimental results obtained from a moving rectangular liquid container validate the simulated sloshing dynamics behavior and the effectiveness of the method. [ABSTRACT FROM PUBLISHER]

The overall performance of emission trading (ET), a market-based emission regulation tool, strongly relies on participants' participation and responses. In order to improve market design, it is important for policy makers to understand the participants' trading behaviors in different market environments. However, human behaviors cannot be easily modeled with conventional analytical methods due to its “bounded rationality” characteristics. In this paper, based on the complementary features between experimental and agent-based computational methods, a hybrid interactive simulation methodology is proposed to solve human behaviors related problems. Human-subjected experiment based on European Union Emissions Trading System price data in 2006 is conducted, the results show that there is no fixed emission trading interval for generation companies, and the strategic behaviors of market participants are observed. Major driving factors of emission trading are categorized into emission price, emission quantity and time related factors, which are in accordance with empirical analysis results on EU ETS 2005–2006 transaction dataset. Furthermore, more human-subjected experiments are conducted under different emission price scenarios to obtain samples for quantitative analysis. Based on thousands of samples obtained, the joint influences of driving factors on emission trading behaviors are analyzed. The quantitative analysis results obtained can reflect the trading patterns of human participants, which provide basis for constructing computer agents that can act as useful substitutes for human participants. [ABSTRACT FROM PUBLISHER]

Physical-layer network coding (PLNC) allows two remote terminals to exchange information in two time slots via a half-duplex relay. In this paper, we consider PLNC in underwater acoustic (UWA) two-way relay networks, with particular attention on the recovery of the network-coded codeword at the relay. Considering multiple paths in UWA channels with large delay spreads and temporal variations, orthogonal-frequency division-multiplexing (OFDM) is used as an underlying modulation. Distinct from existing works which mainly focus on the flat-fading channel and the non-iterative PLNC decoding, we investigate three iterative receivers at the relay in doubly-selective UWA channels. To estimate the network-coded codeword, the three receivers respectively adopt i) a conventional decoding scheme to recover the codewords from two terminals independently; ii) a decoding scheme to recover the network-coded codeword directly, and iii) a joint decoding scheme to recover a composite codeword formed by the codewords from the two terminals. In the time-varying channel, the intercarrier interference (ICI) in the received signal has been explicitly addressed in three receivers. Extensive simulations and experimental results reveal that the decoding scheme for direct recovery of the network-coded codeword cannot work well in the multipath channel, and that with a lower complexity the performance of the iterative separate-decoding scheme can catch up with that of the joint decoding scheme. [ABSTRACT FROM PUBLISHER]

In this paper, we consider the cooperative output regulation of linear multi-agent systems under switching network. The problem can be viewed as a generalization of the leader-following consensus problem of multi-agent systems. Due to the limited information exchanges of different subsystems, the problem cannot be solved by the decentralized approach and is not allowed to be solved by the centralized control. By devising a distributed observer network, we can solve the problem by both dynamic state feedback control and dynamic measurement output feedback control. As an application of our main result, we show that a special case of our results leads to the solution of the leader-following consensus problem of linear multi-agent systems. [ABSTRACT FROM AUTHOR]

Microwave interferometers have been attractive devices for high-precision measurements of displacement-related physical quantities in a variety of scientific and engineering applications. However, due to the long operating wavelength, the displacement measurement resolution of microwave interferometers is limited to the micrometer scale. In this article, we propose and demonstrate a novel technology based on microwave interferometry for displacement measurements with potential picometer resolution. An open-ended (OE) transmission line resonator based on a homemade hollow coaxial cable is explored in proof-of-concept numerical and experimental investigations. The technique involves two stages of displacement sensitivity amplification: one is the open end-based phase sensitivity amplification, and the other is the destructive interference-based phase sensitivity amplification. We experimentally demonstrate a wavelength sensitivity amplification factor of 1800 through spectral interrogation where only the open end-based amplification is involved, and a phase sensitivity amplification factor of 1.4 million through phase interrogation where both the open end-based amplification and the destructive interference-based phase shift amplification are involved, i.e., two-stage phase shift amplified microwave interferometry (TPAMI). The numerical investigations and the experimental results match well. [ABSTRACT FROM AUTHOR]

A GaAs monolithic K-band left-handed frequency multiplier based on a composite right/left-handed coplanar-waveguide transmission line (TL), periodically distributed series planar Schottky varactor diode, and shunt rectangle spiral inductor has been successfully designed and fabricated. The anomalous dispersion of the left-handed TL and strong nonlinearity of the Schottky varactor are combined to effectively generate harmonics when a large signal is applied. The maximum output power of the second harmonic is 6.7 dBm (including 3.85-dBm loss from the measurement system), which was achieved when a 20-dBm fundamental frequency of 13.8 GHz is fed. High conversion efficiency for the second harmonic over a broad frequency range of 16.4–35.2 GHz has been obtained experimentally. [ABSTRACT FROM AUTHOR]

The dynamic surface control (DSC) technique was developed recently by Swaroop et at This technique simplified the backstepping design for the control of nonlinear systems in strict-feedback form by overcoming the problem of "explosion of complexity?' It was later extended to adaptive backstepping design for nonlinear systems with linearly parameterized uncertainty. In this paper, by incorporating this design technique into a neural network based adaptive control design framework, we have developed a backstepping based control design for a class of nonlinear systems in strict-feedback form with arbitrary uncertainty. Our development is able to eliminate the problem of "explosion of complexity" inherent in the existing method. In addition, a stability analysis is given which shows that our control law can guarantee the uniformly ultimate boundedness of the solution of the closed-loop system, and make the tracking error arbitrarily small. [ABSTRACT FROM AUTHOR]

Proposes a neural-network-based approximation method for discrete-time nonlinear servomechanism problem. Problem description; Discussion on approximating the solutions of the discrete regulator equations; Conclusion.