Interface engineering has been employed on commercial Bi0.5Sb1.5Te3 (BST) to obtain synergistically enhanced thermoelectric performance via incorporating amorphous Sb2S3 nano spheres.
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...•Conducting interface engineering via incorporating Sb2S3 in Bi0.5Sb1.5Te3.•Decoupling thermal and electrical properties via introducing Sb/BST interfaces.•Obtaining a high zT of ∼ 1.31 at 330 K in Bi0.5Sb1.5Te3-0.4%Sb2S3.
Tremendous efforts have been focusing on the improvement of p-type (Bi, Sb)2Te3-based thermoelectric materials for commercial applications. In this study, we achieve versatile interface engineering through a surface decoration of Bi0.5Sb1.5Te3 by amorphous Sb2S3 combining with spark plasma sintering, which introduces semi-coherent Sb/Bi0.5Sb1.5Te3 interfaces and dopes S into Bi0.5Sb1.5Te3. Semi-coherent Sb/Bi0.5Sb1.5Te3 interfaces strongly scatter phonons and lower energy carriers, leading to decreased thermal conductivity and increased Seebeck coefficient, while the electrical conductivity is not sacrificed due to the compromise of the slightly reduced carrier mobility by interfacial scattering and the increased carrier concentration by S doping. Benefited from the decoupled thermoelectric properties, a significantly enhanced power factor of 3345.40 μW m−1 K−2 and a low thermal conductivity of 0.78 W m−1 K−1 is obtained in Bi0.5Sb1.5Te3-0.4%Sb2S3, leading to a high peak zT of ∼ 1.31 at 330 K, which shows a 54% enhancement compared with pristine Bi0.5Sb1.5Te3. Moreover, a conversion efficiency of ∼ 7.6% can be predicted in a single leg Bi0.5Sb1.5Te3-0.4%Sb2S3-based module under a cold side temperature of 300 K and hot side temperature of 480 K. This study paves a facile amorphous Sb2S3 induced interface engineering strategy for the development of high performance (Bi,Sb)2Te3-based thermoelectric materials.
In the field of sound source identification, robust and accurate identification of the targeted source could be a challenging task. Most of the existing methods select the regularization parameters ...whose value could directly affect the accuracy of sound source identification during the solving processing. In this paper, we introduced the ratio model ℓ1/ℓ2 norm to identify the sound source(s) in the engineering field. Using the alternating direction method of multipliers solver, the proposed approach could avoid the selection of the regularization parameter and localize sound source(s) with robustness at low and medium frequencies. Compared with other three methods employing classical penalty functions, including the Tikhonov regularization method, the iterative zoom-out-thresholding algorithm and the fast iterative shrinkage-thresholding algorithm, the Monte Carlo Analysis shows that the proposed approach with ℓ1/ℓ2 model leads to stable sound pressure reconstruction results at low and medium frequencies. The proposed method demonstrates beneficial distance-adaptability and signal-to-noise ratio (SNR)-adaptability for sound source identification inverse problems.
Near-field acoustic holography (NAH) based on equivalent source method (ESM) is an effective method for identifying sound sources. Conventional ESM focuses on relatively low frequencies and cannot ...provide a satisfactory solution at high frequencies. So its improved method called wideband acoustic holography (WBH) has been proposed, which has high reconstruction accuracy at medium-to-high frequencies. However, it is less accurate for coherent sound sources at low frequencies. To improve the reconstruction accuracy of conventional ESM and WBH, a sound source identification algorithm based on Bayesian compressive sensing (BCS) and ESM is proposed. This method uses a hierarchical Laplace sparse prior probability distribution, and adaptively adjusts the regularization parameter, so that the energy is concentrated near the correct equivalent source. Referring to the function beamforming idea, the original algorithm with order
can improve its dynamic range, and then more accurate position information is obtained. Based on the simulation of irregular microphone array, comparisons with conventional ESM and WBH show that the proposed method is more accurate, suitable for a wider range of frequencies, and has better reconstruction performance for coherent sources. By increasing the order
, the coherent sources can be located accurately. Finally, the stability and reliability of the proposed method are verified by experiments.
This very paper focuses on the preparation of an eco-friendly and efficient photocatalyst aiming to degrade organic dyes in wastewater. The cheap and abundant straws were carbonized to prepare porous ...carbon pieces in this study. A simple hydrothermal method was employed to prepare the porous carbon/CdS (PC/CdS) composite. CdS nanoparticles were anchored on these porous carbon sheets, forming the PC/CdS composite. The composite was annealed at 300, 400, and 600 °C, respectively, and then these samples were characterized by SEM, TEM, XRD, and FTIR. As an important parameter, the porosities of PC and the PC/CdS were characterized by BET method. Particularly, the photo-electronic response of PC/CdS has been characterized by EIS, PL, and transient photocurrent. It is found that the carrier mobility and shape of PC itself and the annealing process improved the photocatalytic activity, as well as adsorption ability. Those composites were able to thoroughly degrade RhB within 90 min under the irradiation of visible light. What is interesting and quite different from other reports is that there was no conjugated part of RhB left in the solution after photocatalytic degradation.
In this paper, the fault-tolerant capability of the existing stator-flux-oriented decoupling control (SFOC) for the DTP-PM motor is investigated, and a simple fault-tolerant SFOC is further designed ...to enhance fault tolerance. Firstly, the mathematical model of the DTP-PM motor in the stator-flux-oriented rotating coordinate system is analyzed. An SFOC is proposed to guarantee healthy operation performance, considering torque, flux linkage, and harmonic currents. Secondly, the coupling relationship under open-phase conditions is assessed. The assessed result shows that the coupling relationship between the harmonic and fundamental components results in conflicts and poor post-fault operation. Thirdly, the proposed SFOC includes an automatic deactivation module to detect conflicts with a variable threshold. The conflicted harmonic current controllers can be excluded automatically. Hence, fault-tolerant control can be remedied without diagnosing the specific fault scenario, and excellent fault-tolerant capability can be achieved. Finally, experiments on a DTP-PM motor are carried out to verify the feasibility and effectiveness of the proposed strategy.
Deconvolution beamforming has gotten increased attention as a way to improve the spatial resolution of delay-and-sum beamforming. It has the ability to decrease sidelobes and increase resolution. ...However, compared to conventional beamforming, the extra computation of the deconvolution method is a drawback. A more efficient approach is developed to improve the computing speed of the deconvolution method. Specifically, when tackling deconvolution problems, this method improves computational performance by combining Fourier operation with a fast gradient algorithm called the double momentum gradient algorithm. We compare the proposed method with two known effective deconvolution methods, namely the fast Fourier transform non-negative least squares algorithm and the fast iterative shrinkage threshold algorithm. The results of simulation and experiment reveal that the proposed method tends to give a better spatial resolution within a short computational time and is more suitable for engineering applications.
The conventional equivalent source method for near-field acoustic holography is an effective noise diagnosis method using microphone array. However, its performance is limited by microphone spacing, ...so the effect is unsatisfied when the wave number is high. In this paper, to broaden the frequency suitability and improve the performance of sound source reconstruction with low signal-to-noise ratios, a block Bayesian compressive sensing method based on the equivalent source method is proposed. Numerical results show that this proposed method has a good reconstruction performance and makes wideband reconstruction possible. By changing the frequency, location, and signal-to-noise ratio of the sound source, the reconstruction performance of the proposed method can remain stable. Finally, the validity and practicability of the proposed method are verified by experiments.
The acoustic imaging (AI) technique could map the position and the strength of the sound source via the signal processing of the microphone array. Conventional methods, including far-field ...beamforming (BF) and near-field acoustic holography (NAH), are limited to the frequency range of measured objects. A method called Bregman iteration based acoustic imaging (BI-AI) is proposed to enhance the performance of the two-dimensional acoustic imaging in the far-field and near-field measurements. For the large-scale ℓ1 norm problem, Bregman iteration (BI) acquires the sparse solution; the fast iterative shrinkage-thresholding algorithm (FISTA) solves each sub-problem. The interpolating wavelet method extracts the information about sources and refines the computational grid to underpin BI-AI in the low-frequency range. The capabilities of the proposed method were validated by the comparison between some tried-and-tested methods processing simulated and experimental data. The results showed that BI-AI separates the coherent sources well in the low-frequency range compared with wideband acoustical holography (WBH); BI-AI estimates better strength and reduces the width of main lobe compared with ℓ1 generalized inverse beamforming (ℓ1-GIB).
Abstract
The genome of an organism is inherited from its ancestor and continues to evolve over time, however, the extent to which the current version could be altered remains unknown. To probe the ...genome plasticity of
Saccharomyces cerevisiae
, here we replace the native left arm of chromosome XII (
chrXIIL
) with a linear artificial chromosome harboring small sets of reconstructed genes. We find that as few as 12 genes are sufficient for cell viability, whereas 25 genes are required to recover the partial fitness defects observed in the 12-gene strain. Next, we demonstrate that these genes can be reconstructed individually using synthetic regulatory sequences and recoded open-reading frames with a “one-amino-acid-one-codon” strategy to remain functional. Finally, a synthetic neochromsome with the reconstructed genes is assembled which could substitute
chrXIIL
for viability. Together, our work not only highlights the high plasticity of yeast genome, but also illustrates the possibility of making functional eukaryotic chromosomes from entirely artificial sequences.
Single voltage vectors applied in the conventional model predictive torque control(MPTC)for multiphase motors do not only suffer from serious torque and stator flux ripples but also cause the large ...harmonic current.To address the aforementioned challenges,an MPTC using a modified dual virtual vector modulation method is proposed to improve the operational performance of a dual three-phase permanent magnet synchronous motor.Virtual voltage vectors are synthesized as the candidate control set to restrain the harmonic current.A transformation method is introduced to consider both the stator flux and torque in the duty cycle modulation.The torque and stator flux ripples are simultaneously reduced by addressing the limitations of nonuniform units.Furthermore,the null voltage vector is then inserted to expand the modulation range and improve the steady-state performance.Moreover,the sawtooth carrier is adopted to address the challenge of the asymmetric switch sequence caused by the modified modulation.Finally,the experimental results are presented to verify the effectiveness and superiority of the proposed MPTC method.
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