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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]

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]

In remote sensing imaging systems, pan-sharpening is an important technique to obtain high-resolution multispectral images from a high-resolution panchromatic image and its corresponding low-resolution multispectral image. Due to the powerful learning capability of convolution neural networks (CNNs), CNN-based methods have dominated this field. However, due to the limitation of the convolution operator, long-range spatial features are often not accurately obtained, thus limiting the overall performance. To this end, we propose a novel and effective method by exploiting a customized transformer architecture and information-lossless invertible neural module for long-range dependencies modeling and effective feature fusion in this article. Specifically, the customized transformer formulates the panchromatic (PAN) and multispectral (MS) features as queries and keys to encourage joint feature learning across two modalities, while the designed invertible neural module enables effective feature fusion to generate the expected pan-sharpened results. To the best of our knowledge, this is the first attempt to introduce a transformer and a invertible neural network into the pan-sharpening field. Extensive experiments over different kinds of satellite datasets demonstrate that our method outperforms state-of-the-art algorithms both visually and quantitatively with fewer parameters and flops. Furthermore, the ablation experiments also prove the effectiveness of the proposed customized long-range transformer and effective invertible neural feature fusion module for pan-sharpening. [ABSTRACT FROM AUTHOR]

Terahertz (THz) communication is now being considered as one of possible technologies for the sixth generation (6G) wireless communication systems. In this paper, a novel three-dimensional (3D) space-time-frequency non-stationary theoretical channel model is first proposed for 6G THz wireless communication systems employing ultra-massive multiple-input multiple-output (MIMO) technologies with long traveling paths. Considering frequency-dependent diffuse scattering, which is a special property of THz channels different from millimeter wave (mmWave) channels, the relative angles and delays of rays within one cluster will evolve in the frequency domain. Then, a corresponding simulation model is proposed with discrete angles calculated using the method of equal area (MEA). The statistical properties of the proposed theoretical and simulation models are derived and compared, showing good agreements. The accuracy and flexibility of the proposed simulation model are demonstrated by comparing the simulation results of the relative angle spread and root mean square (RMS) delay spread with corresponding measurements. [ABSTRACT FROM AUTHOR]

For the past 50 years, open-ended coaxial lines were commonly employed for the determination of electromagnetic properties of various materials. In this article, the application of an open-ended hollow coaxial cable resonator (OE-HCCR) as a 1-D inclinometer for tilt measurements with 110 nanoradian (nrad) resolution is proposed and demonstrated. The coaxial cable resonant structure is formed between a metal post welded within the coaxial cable at the RF input end and the open end of the coaxial cable. A metal mass block, suspended in proximity to the open end in parallel is used to construct a pendulum structure, serving as the element responsive to a tilt. When the device is tilted, the distance between the mass block and the open end varies due to the displacement of the suspended pendulum. The change in the gap distance modifies the phase reflection coefficient associated with the open end, causing the resonance frequency of the coaxial cable resonator to change. By tracking the resonance frequency, the coaxial line resonator is effectively used as an inclinometer. The experimental results demonstrated that the novel device has a measurement resolution of 110 nrad over a range of 0–3 milliradians (mrad). Additionally, based on the same principle, a 2-D inclinometer based on two perpendicularly aligned OE-HCCRs, useful for simultaneous tilt measurements in two orthogonal dimensions is demonstrated. The open-ended coaxial cable resonator-based inclinometer holds several advantages, including high resolution, robustness, cost effectiveness, ease of signal interrogation, and user-configurable sensitivity and dynamic range. [ABSTRACT FROM AUTHOR]

In this paper, a novel 3-dimensional (3D) non-stationary geometry-based stochastic model (GBSM) is proposed to mimic the ship-to-ship multiple-input multiple-output (MIMO) communication channels. To reflect the realistic maritime propagation environment, the effects of rough sea surface scattering and evaporation duct propagation are investigated in the proposed channel model. The model considers the movements of transmitter (Tx), receiver (Rx), and scatterers, and is capable of capturing the channel characteristics, including non-stationary characteristics, spatial consistency, location-dependent property, etc. Through taking the array cluster evolution into account, the proposed channel model can describe massive MIMO channels and can easily switch to conventional MIMO channel model by adjusting corresponding parameters. Based on the proposed model, key statistical properties like delay/angular/Doppler power spectrum density (PSD), space-time correlation function (STCF), stationary interval, and root mean square (RMS) Doppler/delay spreads in multi-scenarios are derived. The usefulness and accuracy of the proposed model are demonstrated by comparing theoretical results, simulation results, and corresponding measurement results. [ABSTRACT FROM AUTHOR]

This article reports a technique to embed optical fiber into a copper mold plate for generating high-density thermal maps of the mold during the process of metal casting. The temperature measurements were based on acquiring and interpreting Rayleigh backscattering (RBS) signals from embedded fiber, using the interrogation technique of optical frequency domain reflectometry (OFDR). The instrumented mold plate was used to perform a cast-iron dip test and a steel dip test in a 200 lb induction furnace. The maximum temperatures recorded by the embedded fiber-optic sensors were 469 °C and 388 °C in the cast-iron and steel dip tests, respectively. The closely spaced and rapidly fluctuating temperature features that were imparted to the mold wall during solidification were successfully mapped with a high spatial resolution (0.65 mm) and a fast measurement rate (25 Hz) using a commercial OFDR interrogator (LUNA ODiSI 6108). Moreover, the thickness of the solidified steel shell was measured, and a thickness map of the shell was generated. A good correlation was observed between the thickness of the solidified shell and the temperature of the mold, as regions with higher and lower temperatures in the thermal profile of the mold corresponded to thicker and thinner areas on the shell, respectively. The dip testing experiments demonstrate that RBS-based fiber-optic sensing is a feasible and effective method for generating information-rich thermal maps of caster molds. The information obtained from thermal maps can be useful for improving the quality of the metal and productivity of the metal casting process. [ABSTRACT FROM AUTHOR]

This article presents an ultrasensitive open-ended hollow coaxial cable resonator (OE-HCCR) that was trained to detect impact events that occurred in the surrounding space through machine learning (ML) techniques. First, inspired by the well-known mass-based accelerometer, for the first time, we propose an OE-HCCR-based accelerometer with the addition of an inertial mass block as the element responsive to acceleration. The OE-HCCR is formed by a metal shorting post welded at the RF input end and the open end of the cable. The instantaneous displacements of the mass block mounted at the endface of the cable due to accelerations lead to variations of the gap distance between the mass block and the endface of the coaxial line, which can be accurately metered by the coaxial resonating structure. Impact events that occur in the surrounding space of the OE-HCCR result in vibrations transmitted to the OE-HCCR system and thereby measured by the OE-HCCR. Second, we demonstrated that employing ML algorithms to analyze the transient responses from the OE-HCCR makes unambiguous mappings between the transient responses of the OE-HCCR and the sources of vibrations possible, due to the ultrahigh sensitivity of the OE-HCCR and the spatial anisotropy of matter in the surrounding space. The preliminary results demonstrate the feasibility of using ML-assisted OE-HCCR system for locating impact events and recognizing different impactor implements that caused the impact events. [ABSTRACT FROM AUTHOR]