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The stellarator Wendelstein 7-X (W7-X) has been designed to show that optimized stellarators can achieve and sustain fusion relevant plasma conditions. One of the main optimization criteria was the reduction of the neoclassical transport, which is considered as one of the most critical issues of the stellarator concept. While the demonstration of the neoclassical optimization will definitely be one...
Exploitation and using of clean and renewable energy to improve the domestic energy structure is important for building smart city. Photovoltaic (PV) power generation is a good choose, and modules inspection is an important direction of PV power generation. The manual inspection is a common way but is not feasible for large-scale PV systems in practice due to low efficiency, high error rate and long...
Approaches towards a linear THz accelerator technology based on a novel multilayer waveguid structure, are discussed. Theoretical and first experimental results on laser based THz generation, guns, accelerators as well as compact X-ray sources based on those devices are presented.
Ultrafast photoconductive switches were fabricated from GaAs embedded with ErAs nanoparticles and tested in two antenna types: a self-complementary square spiral, and a slot antenna designed for half-wave resonance at 567 GHz. These devices are designed for driving with 1550nm lasers. At least ∼46 μW of THz average power was generated from the spiral, and ∼5 μW from the resonant slot. This is the...
We investigate effects of bound water molecules on optical phonon vibrations that occur at frequencies as low as the terahertz (THz) region (300 GHz–10 THz) with both spectroscopy and molecular dynamics simulation.
The use of Inertial Measurement Unit (IMU) for gait analysis is gaining popularity because of its advantages of low cost and non-limited workspace. In this context, researchers are focusing on methods for automated data analysis. For example, many algorithms for stride length estimation have been developed. These algorithms rely on event detection to compute gait parameters during walking and on orientation...
Frequency modulated (FM) signals are frequently encountered in radar signal processing. In practice, such signals may experience distortions due to target radar cross section fluctuation, propagation fading, and line-of-sight obstruction. Such distortions make time-frequency presentations and analyses challenging. The problem becomes even more difficult for data with gapped missing samples, i.e.,...
In this paper, we propose a novel sparse array design for direction-of-arrival estimation based on the fourth-order statistics of the received signals. The utilization of fourth-order statistics provides a higher number of degrees of freedom and flexibility as compared to the commonly used covariance-based methods. The proposed sparse array design scheme yields the fourth-order difference co-array...
Benefitting from its non-volatility, low power, high speed, nearly infinite endurance, good scalability and great CMOS compatibility, magnetic tunnel junction (MTJ) embedded in conventional CMOS logic circuits has been proposed as one potentially powerful solution to introduce non-volatility in today's programmable logic circuits, which is envisioned to extend the Moore's law [1].
In this paper, we consider robust direction-of-arrival (DOA) estimation for an array that contains mis-calibrated sensors with unknown gain and phase uncertainties. We develop two robust DOA estimation algorithms based on the maximum correntropy criterion (MCC). In the first algorithm, adaptively optimized weighting factors are obtained and applied to each sensor to effectively mitigate the effect...
As a new emerging technology for wireless communications, massive multiple-input multiple-output (MIMO) faces a significant challenge to deploy a separate receiver chain of front-end circuits in a dense circuit board. In this paper, we apply the compressive sensing technique to reduce the required number of front-end circuits and the overall computational complexity. Unlike the commonly adopted random...
Radar-based automated fall detection systems are considered as an important and emerging technology for elderly assisted living. These radar systems provide non-intrusive sensing capabilities to detect fall events. Various studies have used micro-Doppler signatures to determine falls. However, Doppler radar fall detection systems suffer false alarms stemming from other sudden non-rhythmic motion articulations...
We propose a nonstationary jammer signal suppression technique based on parametric sparse reconstruction, where sparsely sampled data are considered. By assuming nonstationary jammers that are characterized by polynomial phase signatures, a data-dependent parametric dictionary matrix is designed. In order to obtain an accurate instantaneous frequency estimation at a low computational complexity, we...
A model is constructed for extrinsic photoconductivity in GaAs heavily doped with Er and driven around 1550 nm. The model is based on internal photoionization of ErAs nanoparticles in the diameter range 2.0 to 2.5 nm, which occurs via a resonant, bound-to-continuum electron transition between the Γ-point in the atomic-like ErAs and the Γ-valley in the GaAs. The model is consistent with all experimental...
We measured different sub-fractions of an asphaltene sample with a THz-TDS system. The results demonstrate good correlation between the terahertz absorption coefficient and the polarity of different sub-fractions.
In this newly reported discovery, common THz absorption signatures from lactose and biotin are found to significantly “red-shift” in frequency with increase in hydration, especially in the hydration range of ∼10 to 20% by weight. Interestingly, the associated linewidth (i.e., FWHM) sometimes broadens (consistent with the Lorentzian oscillator model) as in biotin, but other times narrows somewhat,...
Single image-based HDR imaging can inherently remove ghost artifacts which appear in multiple image-based HDR imaging. Most existing single-exposure HDR imaging methods apply complicated handing to overexposed areas in image, which perplexes the algorithm and introduces the probability of generating artifacts; moreover, they do not take into account the imaging properties of the camera. In this paper,...
We report recent research progress on the strong coupling between an ensemble of quantum emitters (QEs) or chiral molecules and plasmon in the nanoparticle cluster, including strong interaction between chiral molecules and orbital angular momentum of photon, multi-qubit entanglement for two-level QEs, resonant energy transfer and so on.
Based on exact numerical calculations and physical analyses, we demonstrate that there are two types of flat band in two-dimensional (2D) magnetic photonic crystals (PhCs). One has trivial topology with zero Chern number and the other has non-trivial topology with nonzero Chern number. Physical origins and topological properties of two types of flat band are studied comparatively.
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