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Concrete thermal parameters in a natural pouring environment are essential inputs for simulating the temperature field of a concrete dam. This paper proposes a two-stage thermal parameters inversion method for a concrete dam based on optimal temperature measuring point selection to improve the accuracy of parameters. Firstly, a selection method of optimal measuring point for thermal parameters inversion is presented and the temperature response sensitivity of measuring points when the parameters disturb is taken as the critical evaluation index. And then, an inversion model is established based on support vector regression (SVR) and particle swarm optimization (PSO). Finally, the proposed method is applied to the thermal parameter inversion of a concrete dam. The results show that the proposed method is effective for improving the inversion accuracy and obtaining accurate parameters. The average error of the inversion results based on the SVR-PSO model is 28.54% lower than that of the genetic algorithm optimization using a back propagation neural network (BPNN-GA). Besides that, the average error of the inversion results based on the optimal measurement points is 35.57% lower than that of the nonoptimized ones. [ABSTRACT FROM AUTHOR]

The structural and electronic transport properties of tetragonal CH3NH3SnBr3 single crystals (T-MASnBr3 SCs) are rarely reported. In this study, we synthesized T-MASnBr3 single crystals by volatilizing DMF solvent at room temperature. The crystal system and space group of the T-MASnBr3 SC are tetragonal and P4/mmm, respectively. In addition, the nitrogen atom in the methylamine group exhibits position disorder. The band gap of the T-MASnBr3 SC was determined to be 2.07 eV using the Tauc plot. Six fluorescence peaks and a lifetime up to 10 microseconds were observed in the steady-state fluorescence spectra and time-resolved fluorescence spectra of the T-MASnBr3 SC, respectively. The carrier mobility (electron) of T-MASnBr3 was 321 cm2 V−1 s−1. The curve of ln(square resistance) against T−1 was a straight line. The value of the activation energy (Ea) was 5421 J mol−1. The stability of the T-MASnBr3 SC was good before 473 K. The results indicate that T-MASnBr3 SCs have promising applications in the field of temperature sensors. [ABSTRACT FROM AUTHOR]

Multiphase permanent magnet (PM) motors are popularly adopted for their high torque density, high efficiency, and good fault tolerance. Open-circuit and short-circuit faults can result in high fluctuating torque and deteriorated dynamic performance. This article proposes a novel direct torque control (DTC) approach based on disturbance observer (DOB) to minimize the torque pulsations and enhance dynamic performance of a five-phase PM motor under open-circuit and short-circuit fault conditions. The novelty of the proposed strategy is the development of fault-tolerant switching table based on closed-loop mode of third harmonic current regulation and the incorporation of DOB. Based on the switching table, the proposed method can restrain the torque fluctuations caused by open-circuit fault and suppress y-axis current. The DOB is introduced to eliminate the external disturbances, which include torque fluctuations caused by short-circuit current and unmodel dynamic. Then, the proposed strategy is applicable to the PM motor, whose back electromotive force contains third harmonic, under open-circuit or short-circuit fault condition. This fault-tolerant DTC strategy can not only smooth fluctuating torque and ensure that its dynamic performance reaches the healthy performance, but also enhance the robustness against the external disturbances under both open-circuit and short-circuit fault conditions. The simulation and experimental results are presented to validate the proposed strategy. [ABSTRACT FROM AUTHOR]

The transition metal oxide Nb2O5 has advantages and potential in electrochemical catalysis. However, routine Nb2O5 catalyst has large bulk resistance and poor conductivity. In this study, the Nb2O5 crystal lattice@graphene oxide (Nb2O5‐CL@GO) composite is prepared. The lattice atoms effectively couple to the GO atoms because of few atom layers in Nb2O5‐CL@GO. Face‐type coupling (FTC) is formed between the crystal‐lattices face and GO face, which is benefited to increase the electron‐coupling area, to increase the synergistic effect. In thick Nb2O5 layer@GO (Nb2O5‐TL@GO), only edge atoms in the thick Nb2O5 layer are directly electron coupled with the GO, while the surface atoms on the thick Nb2O5 have weak electronic coupling to GO. Therefore, line‐type‐coupling (LTC) in Nb2O5‐TL@GO reduce exposure of electron‐coupling area. Compared with Nb2O5‐TL@GO, Nb2O5‐CL@GO exhibited excellent electrocatalytic activity and metallic properties in the electrolyte. In addition, the performance of Nb2O5‐CL@GO composite as an electrocatalytic electrode in dye‐sensitized solar cells is superior to that of the noble Pt. The power conversion efficiency (PCE) is 10.81% under 1‐sun illumination (AM 1.5 G, 100 mW cm−2). Compared with Si solar cells, DSCs based on Nb2O5‐CL@GO composite is suitable for use in low illumination intensity and radiation angle. Finally, the DSCs based Nb2O5‐CL@GO composite has good stability. The results are of great interest in the materials and interface science, electrocatalysts, and energy conversion. [ABSTRACT FROM AUTHOR]

The unconsolidated near surface and large, daily temperature variations in the desert environment degrade the vertical seismic profiling (VSP) data, posing the need for rigorous quality control. Distributed acoustic sensing (DAS) VSP data are often benchmarked using geophone surveys as a gold standard. This study showcases a new simulation-based way to assess the quality of DAS VSP acquired in the desert without geophone data. The depth uncertainty of the DAS channels in the wellbore is assessed by calibrating against formation depth based on the concept of conservation of the energy flux. Using the 1D velocity model derived from checkshot data, we simulate both DAS and geophone VSP data via an elastic pseudo-spectral finite difference method, and estimate the source and receiver signatures using matching filters. These field geophone data show high amplitude variations between channels that cannot be replicated in the simulation. In contrast, the DAS simulation shows a high visual similarity with the field DAS first arrival waveforms. The simulated source and receiver signatures are visually indistinguishable from the field DAS data in this study. Since under perfect conditions, the receiver signatures should be invariant with depth, we propose a new DAS data quality control metric based on local variations of the receiver signatures which does not require geophone measurements. [ABSTRACT FROM AUTHOR]

The gradation properties of earth-rock dam-filling materials primarily influence their mechanical properties after compaction. Herein, combined with the characteristics of rockfill gradation detection (RGD) requirements in practical engineering, an intelligent detection method for rockfill gradation based on video image (VI) recognition technology is proposed and applied to engineering applications. By designing a device for VI recording, multi-group RGD tests are conducted. Further, a method for rockfill identification and particle size gradation transformation based on VI is proposed. The accuracy and error of the RGD in traditional screening and VI recognition method are compared and analyzed. The results of the laboratory tests and engineering applications in a construction site reveal that the proposed RGD method is highly efficient, precise, and robust. • A special rockfill video image (VI) recording device is designed. • An intelligent control model for the VI recording parameters is developed. • A systematic and comprehensive RGD method based on VI recognition is proposed. [ABSTRACT FROM AUTHOR]

Abstract A novel kind of hollow carbon spheres with artificial surface openings is fabricated as highly effective supercapacitor electrode. This kind of carbon sphere possesses typical hierarchical mesoporous structure with surface area of 670.0 m2 g−1, much higher than that of the conventional hollow carbon spheres and solid carbon spheres. The electrochemical performance of the prepared hollow carbon spheres with surface openings, hollow carbon spheres and solid carbon spheres electrode are evaluated in acidic aqueous electrolyte. The hollow carbon sphere with surface openings electrode shows the optimal capacitive performance due to the specific surface openings and hierarchical mesoporous structure which can provide a large ion-accessible surface area and a loose channel for the electrolyte ions to diffuse into the internal of the spheres, making the internal charge storage sites work more effectively. The hollow carbon spheres with surface openings electrode achieves a remarkable specific capacitance of 272.2 F g−1, much higher than that of the hollow carbon spheres and solid carbon spheres. Besides, the hollow carbon spheres with surface openings preserves 96.9% of its initial capacitance after 10000 charge-discharge cycles, suggesting a perfect cycle life. [ABSTRACT FROM AUTHOR]

Multiphase permanent-magnet (PM) brushless motors are popularly adopted for their high efficiency and high power density. However, short-circuit phase fault results in serious problems, such as increased torque fluctuations and deteriorated dynamic performance. This paper proposes a new vectorial approach to minimize pulsating torque and improve dynamic performance in a five-phase PM motor with short-circuit fault. The novelty of the proposed strategy is voltage feedforward compensation based on the relation of the short-circuit current and its fault-phase back electromotive force. First, the compensatory voltages are used to eliminate the impact of the short-circuit current. Then, its combination with the orthogonal reduced-order transformation matrices derived from fault-tolerant current references can improve the dynamic performance of the faulty PM motor. The effect of the short-circuit phase fault on the PM motor model under rotating synchronous frame is also discussed. This control strategy allows minimal reconfiguration of the control structure from healthy operation to fault-tolerant one and exhibits the improved dynamic performance. The simulated and experimental results are presented as validation for the proposed strategy. [ABSTRACT FROM PUBLISHER]

A five-phase fault-tolerant permanent-magnet (FTPM) motor can offer high torque density, low torque ripple, and good fault-tolerant capability. In order to improve operation performance under an open-circuit fault condition, this paper proposes a new remedial field-oriented control (RFOC) strategy for a five-phase FTPM motor. The novelty of the proposed RFOC strategy lies in the orthogonal reduced-order transformation matrix, which is derived from the fault-tolerant current references, and a new zero-sequence current related to torque ripple. The pulsation of the neutral voltage can be neglected in the RFOC strategy, having no effect on the control action. Also, the effect of the open-circuit fault on the motor drive model under the transformation matrix is discussed. A five-phase FTPM motor drive is prototyped and the proposed RFOC strategy is evaluated in terms of the steady-state and dynamic performances. The simulated and experimental results are given to verify the proposed strategy. [ABSTRACT FROM PUBLISHER]

This paper investigates the unbalanced magnetic force (UMF) produced by angular eccentricity in a magnetic screw. The principle of eccentricity is briefly outlined and an analytical expression that can be used to predict UMF of a magnetic screw is established. A 3D magnetic screw model with helically magnetized permanent magnets (PM) has been built and simulated in ANSYS Maxwell with different angular eccentricities. Comparing the finite elements (FE) simulation and analytical calculation results, there is a certain difference in the UMF of the magnetic screw, which is also caused by the asymmetry of the magnetic screw structure. It has been shown that compared to the linear tubular PM motor with the same thrust force capability, the magnetic screw has a much small UMF, which greatly simplifies the mechanical design of the magnetic screw. [ABSTRACT FROM AUTHOR]

Tubular motors are suitable for active vehicle suspension due to their zero net radial force and volumetrically efficient. This paper proposes a new low-cost tubular fault-tolerant (TFT) interior permanent-magnet (IPM) motor for the high reliability operation of the active vehicle suspension system. The key is that the proposed motor incorporates the concept of fault-tolerant teeth to provide the desired decoupling among phases and adopts the ferrite magnet material to reduce the usage of rare-earth PMs. Its electromagnetic performances are investigated, such as flux linkage, back electromotive force, mutual- and self-inductances, and detent and thrust forces. A finite-element method is employed to verify the theoretical analysis, showing that the proposed TFT PM motor not only has the merits of low-cost, strong mechanical integrity, but also offers good fault-tolerant ability and high thrust force capability. [ABSTRACT FROM PUBLISHER]

common feature in seismic imageries of the crust and mantle is a layering pattern. Layering structures do exist in multiple scales, such as layered strata and unconformities in local and regional scales, and undulating seismic discontinuities in the crust and mantle. However, layering artifact also exists due to limitations in seismic processing and data coverage. There is a tendency for seismic stacking methods to over-map reflectors and scatters into along-isochron layers. In contrast, seismic tomography methods tend to under-map sub-horizontal layers with along-raypath smears and artifacts of various de-mean processes. To better identify signals and artifacts in seismic imageries, it is necessary to understand the origins of various artifacts and make careful comparison between the solutions of different data and methods. [ABSTRACT FROM AUTHOR]

Seismic studies of the crustal structure beneath the Three Gorges Reservoir (TGR) region in Central China have been limited by the sparse and uneven distribution of seismic stations. To increase the station coverage, we made three deployments of a mobile seismologic array in the TGR region during the three summers from 2008 to 2010. Here we present interpretations along a west-east profile through the central TGR region based on new seismic waveform data and a velocity model constrained by regional earthquake data. Two strong mid-crustal reflection interfaces at depths around 10 and 20 km are seen under the TGR. The shallow reflector defines the bottom of the Zigui (秭归) basin. The new waveform data show that the amplitude of the Moho reflection is quite weak, and beneath the Moho, there is a strong reflector around 54-km depth. It is likely that in the TGR region, the Moho is a gradient rather than a sharp boundary. We speculate that the gradient Moho and the 54-km-deep reflector in the upper mantle in the TGR region may be by-products of the Qinling (秦岭)-Dabie (大别) orogen. [ABSTRACT FROM AUTHOR]

For the first time, nonstoichiometric WO2.72 was used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Oxygen-vacancy-rich WO2.72 nanorod bundles with notable catalytic activity for triiodide and thiolate reduction were prepared in this study. The photovoltaic parameters of dye-sensitized solar cells (DSSCs) with WO2.72 nanorod bundles as CEs are superior compared with those of the WO3-based cells, and nearly the same as those of the precious metal Pt-based cells. In a non-corrosive organic redox couple, the performance of WO2.72 CEs is better than that of Pt and WO3 CEs in DSSCs. [ABSTRACT FROM AUTHOR]

Abstract: We hypothesized that lack of a functional serotonin transporter (SERT) would increase basal blood pressure and enhance the development of deoxycorticosterone acetate (DOCA)-salt hypertension compared to wild type (WT) controls. Mean arterial blood pressure was measured in WT and SERT knockout (KO) mice and rat models through radiotelemetry. Basal blood pressures were not different between respective WT and KO. Moreover, blood pressure elevated similarly (∼50 mm Hg) in all strains given DOCA and salt. Thus, the lack of functional SERT did not prevent development of DOCA-salt induced hypertension or modify basal blood pressure significantly. [Copyright &y& Elsevier]

A facile and eco‐friendly dimethyl sulfoxide‐mediated solution aging (DMSA) treatment is presented to control the crystallization dynamics of methylammonium (MA)‐free wide‐bandgap (WBG) perovskite films, enhancing film quality, and morphology for high‐performance tandem solar cells. The comprehensive structural, morphological, and characterization analyses reveal that the DMSA treatment significantly enhances composition and morphology homogeneity while suppressing halide segregation. Consequently, opaque, and semi‐transparent MA‐free WBG perovskite solar cells (PSCs) exhibit remarkable power conversion efficiencies (PCEs) of 18.28% and 17.61%, respectively. Notably, the unencapsulated DMSA‐treated devices maintain 95% of the initial PCE after 900 h of continuous operation at 55 °C ± 5 °C. Furthermore, stacking semi‐transparent DMSA‐treated PSCs as top cells in a 4T tandem configuration, along with silicon heterojunction (SHJ), lead–tin (Pb–Sn) alloyed PSCs, and organic photovoltaics (OPV) as bottom cells, yields impressive PCEs of 28.09%, 26.09%, and 25.28%, respectively, for the fabricated tandem cells. This innovative approach opens new avenues for enhancing the photo‐stability and photovoltaic performance of perovskite‐based tandem solar cells. [ABSTRACT FROM AUTHOR]

The structure, mobility and memristor properties of tetragonal CH3NH3PbBr3 single crystals (T-MAPbBr3 SC) are rarely reported. In this study, we synthesized T-MAPbBr3 SC with the P4/mmm (123) space group by the growing, dropping and growing (GDG) crystal seed method. A CH3NH3+ cation is a disordered state in T-MAPbBr3 SC. The mobility values of T-MAPbBr3 SC under light and dark conditions are 464.28 and −1685.3 cm2 V−1 s−1, respectively. The carrier types under light and dark conditions are holes and electrons, respectively. The memristor based on T-MAPbBr3 SC has a wide and low operating voltage window (0–0.9 V). The high and low resistances of the memristor based on T-MAPbBr3 SC achieve values of 41 and 0.35 GΩ, respectively. The values of high and low resistances are relatively stable for 100 cycles. Thus, the memristor device based on T-MAPbBr3 SC has good applications in the field of memristors. [ABSTRACT FROM AUTHOR]

Lead halide‐based salts exhibit good photoelectric properties; however, the use, leakage, and recovery of toxic lead require careful consideration. Therefore, developing a lead‐free optoelectronic material conveniently and quickly is very important. Moreover, there is relatively little research on the salts of bismuth halides. In this study, we synthesized [PEA]3[Bi2I9] single crystals (SC) by volatilizing N,N‐dimethylformamide (DMF) solvent at 70°C. The crystal system and spatial group of [PEA]3[Bi2I9] are monoclinic and P21/n, respectively. The Tauc plot reveals the optical band gap of the [PEA]3[Bi2I9] SC at 2.048 eV. The carrier mobility of [PEA]3[Bi2I9] SC is 47.4 cm2 V−1 s−1. Steady‐state fluorescence and time‐resolved fluorescence spectrum indicate that there are four fluorescence peaks and about 7 μs lifetime, respectively. The photodetector based on [PEA]3[Bi2I9] SC under different voltages (0.5, 1, 1.5, 2, and 2.5 V) exhibits stability and regularity with turning‐on/off of the light. In addition, thermogravimetric analysis (TGA) tests indicate that [PEA]3[Bi2I9] SC has considerable thermal stability at temperatures up to 260°C, showing promise for becoming a high temperature resistant and nontoxic sensor with good application prospects. [ABSTRACT FROM AUTHOR]

This paper describes parallel simulation of the memory/computation-intensive acoustic wave equation with CPU template buffer optimization. Considering the 8-core CPU shared storage platform as an example, we obtain a one-time speed-up ratio of 6.7× compared with the serial program by using a coarse-grained OpenMP parallel scheme. Then, data is vectorized on the template buffer using the single instruction-multiple data (SIMD) technique to further exploit the computing potential of the CPUs. We apply an 8-channel parallel vector to simulate seismic wavefields with the 256-bit advanced vector extensions (AVX) instruction set. This increases the computing bandwidth, thus eliminating a significant volume of the computing instructions and obtaining a secondary speed-up ratio of 3–7×. In addition, we use 32-byte data alignment, shortest data direction vectorization, and loop tiling optimization algorithm to achieve faster program execution. Finally, we analyze the factors affecting the secondary speed-up of AVX through three-dimensional modeling experiments with the salt model. The results indicate that the memory, cache, and register can better cooperate with each other and the speed-up is increased by optimizing the AVX algorithm. [ABSTRACT FROM AUTHOR]

Rapidly finding a new type of perovskite-like photoelectric material is very important. However, the preparation process and device construction of current electrodes are complicated during the screening of photoelectric materials. In addition, interdigital electrodes (IEs) based on Au, Ag, and other noble metals are very fragile and easily punctured during repeated testing. In this study, we prepared durable, low-cost, and convenient IEs on flat indium tin oxide (ITO) with a distance of 70 microns by laser etching. To prove the feasibility and effectiveness of the ITO-IEs, classic mixed cationic perovskites (MCPs) were selected and prepared on ITO-IEs to test their photoelectric performance. The photocurrent density of IEs based on MCPs reaches 21.68 μA cm−2 at 386 nm, 30 W m−2, and 2.5 V bias voltage. The photocurrent response of the MCP ITO-IEs is effective up to 0.5 W m−2, indicating high photocurrent sensitivity. The values of R and D based on MCP ITO-IEs are 7.23 mA W−1 and 2.36 × 1010 Jones at 386 nm with 30 W m−2 and 2.5 V bias voltage, respectively. These results indicate that durable, low-cost, and convenient ITO-IEs and design thought can effectively screen new perovskite-like photoelectric materials. [ABSTRACT FROM AUTHOR]

To solve the problems of poor positioning accuracy and non-automatic processing seen in the machining of long ladder shaft gears, a fixture structure scheme with a new type of double collect chuck (DCC) is proposed. The design rationality, clamping stability, and repeat clamping positioning accuracy of the proposed DCC were analyzed and investigated based on theory calculation, simulation analysis, and engineering application tests. First, the clamping performance of DCC was investigated through theory calculation and simulation analysis. The test results showed that the structure of DCC maintained effective clamping and the repeat clamping positioning accuracy was steadily controlled within 0.008 mm. Meanwhile, efficiently automated machining of long ladder shaft gear was realized based on extended design and engineering application of automatic up and down mechanism when the structure of DCC was applied. Furthermore, the machining accuracy of the gear was steadily controlled within DIN8 (DIN5480-2 standard). Additionally, based on extended design and engineering tests, the automatic up and down machining improves production efficiency and machining accuracy. Thus, the novel fixture structure scheme provides a new approach for automatic up and down machining of long ladder shaft gear. [ABSTRACT FROM AUTHOR]

The self-discharge and effumability of supercapacitors with aqueous electrolytes are prevalent problems. In this study, we used Na2S2O3·5H2O as the electrolyte for aqueous supercapacitors. Na2S2O3 in Na2S2O3·5H2O can dissolve in crystalline water molecules by itself and the transformation between the solid and liquid states of Na2S2O3·5H2O electrolytes is reversible. The electrolyte based on liquating Na2S2O3 in 5H2O electrolytes has better thermal stability than that based on 2 M Na2S2O3 and 2 M KOH electrolytes. The electrochemical result indicates that the energy storage mechanism of a supercapacitor based on liquating Na2S2O3 in 5H2O leads to a double-layer supercapacitor via Na+ and S2O32− ion adsorption. The self-discharge behavior of the supercapacitor using liquating Na2S2O3 in 5H2O is effectively suppressed by the slow charge redistribution of Na+ and S2O32− ions in solid electrolytes formed from the liquid state. Finally, the supercapacitor using liquating Na2S2O3 in 5H2O has good cycling stability. [ABSTRACT FROM AUTHOR]

Machining of deep hole keyway often suffers from low processing accuracy, low processing symmetry degree between keyway and the reference plane and is difficult to control. In order to enhance the processing quality, a mathematical model of space symmetry error was established based on space projection, orthogonal combination and linear fitting methods so as to study rotatable and shift-able space objects. The space symmetry error was separated into included angle error and displacement error between the fitting straight line and the benchmark line. Through included angle rotation and location measurement along with quantitative translation, the space symmetry error compensation was realized. On the basis of the proposed methods, a Double combined manual self-centering fixture (DCMSF) was designed to realize the radial self-centering and axial location for effective clamping of deep hole keyway, and the reference plane of built-in straight slot was derived out to make it detectable and controllable. Meanwhile, an Online multi-degree of freedom symmetry detection device (OMFSDD) and corresponding Numerical control (NC) programs were also designed for automatic detection and control of symmetry error. Subsequently, mass production of high symmetric deep hole keyway were realized by means of NC gear shaper servo control of rotating shaft angle compensation and bi-directional cutter back-off amount translation compensation, and combination of NC control of fixed angle processing. Deep hole keyway processing experiments indicate that the proposed method can steadily keep the symmetry within 0.03 mm. Thus, the rationality and accuracy of the proposed method was validated which provides a novel approach to high precision deep hole keyway processing. [ABSTRACT FROM AUTHOR]

The n-type Ce:ZnO (NL) grown using a hydrothermal method was deposited on a p-type boron-doped nanoleaf diamond (BDD) film to fabricate an n-Ce:ZnO NL/p-BDD heterojunction. It shows a significant enhancement in photoluminescence (PL) intensity and a more pronounced blue shift of the UV emission peak (from 385 nm to 365 nm) compared with the undoped heterojunction (n-ZnO/p-BDD). The prepared heterojunction devices demonstrate good thermal stability and excellent rectification characteristics at different temperatures. As the temperature increases, the turn-on voltage and ideal factor (n) of the device gradually decrease. The electronic transport behaviors depending on temperature of the heterojunction at different bias voltages are discussed using an equilibrium band diagram and semiconductor theoretical model. [ABSTRACT FROM AUTHOR]

• A continuum-discrete multiscale coupling (CDMC) method for the pristine and defected SWCNTs is proposed. • A variationally consistent meshless computational scheme is built based on the proposed nonlinear multiscale model. • CDMC method is accurate and efficient for nonlinear mechanics of pristine and defected of SWCNTs. • CDMC method is suitable for large scale problems of SWCNTs, especially containing defects. A continuum-discrete multiscale coupling (CDMC) method is developed for predicting the large deformation and buckling behaviors of pristine and defected single-walled carbon nanotubes (SWCNTs). With the use of the moving least squares (MLS) approximation as the linkage for the deformations of the discrete atomic structure and the corresponding continuum model, the delicate microstructures of pristine or defected SWCNTs which possess abnormal properties can be involved accurately in the mechanic model built by this CDMC method. Based on the proposed CDMC method, a variationally consistent meshless computational scheme is developed. As the degree of freedom of SWCNTs can be chosen freely in the context of CDMC method, the numerical computational efficiency is higher than that of the fully atomistic simulations. Various numerical tests are carried out for simulating the nonlinear large and buckling deformations of SWCNTs. The results compared with those of the fully atomistic simulations show that CDMC method is accurate and efficient for predicting the nonlinear mechanical properties of pristine and defective SWCNTs and has great potential for dealing with large scale boundary problems. [ABSTRACT FROM AUTHOR]

In modern education, personalized learning has garnered increasing attention, with cognitive diagnosis (CD) serving as a fundamental component. The objective of CD is to deeply comprehend students' cognitive abilities, thereby identifying individual differences and providing support for personalized learning. However, many existing models ignore the influence of data noise and confidence in students' responses. In addition, most existing methods equally extract evidence of students' strengths and weaknesses from their overall responses, disregarding the characteristics of various types of relationships in students' correct and incorrect responses. To this end, this study proposes a Confidence-guided Multigraph Model (CMM) for CD. First, to capture the changes and uncertainties in the student's cognitive process, CMM dynamically calculates the confidence scores of the students' responses. Second, CMM constructs multiple graphs to represent various relationships in students' correct and incorrect responses. Then, CMM aggregates the unique information within the students' correct and incorrect responses from various graphs. Finally, CMM uses a joint training strategy of multigraph iteration to simulate students' cognitive ability in multiple dimensions. Extensive experimental results on two real-world datasets clearly demonstrate the efficacy of our proposed model. This innovative approach provides a novel perspective for the development of CD and lays the foundation for more accurate personalized learning support. • We considered confidence information to reduce the impact of data noise and sparsity. • A model using multi-graph to represent different types of relationships is developed. • We design a joint training strategy to integrate multiple levels of information. • Our model achieves more precise and robust results in diagnosis results. [ABSTRACT FROM AUTHOR]

Seafloor acoustic reflectivity is fundamental for both underwater detection and ocean acoustic field prediction, especially in shallow-water offshore regions. This paper presents a procedure to estimate the seafloor reflectivity in shallow water based on the direct wave and seafloor reflection data from single-channel seismic records of sparker sources. We apply the procedure to a seismic line acquired in the western part of the Taiwan Strait. To resolve the uncertainty in the inversion results, we implement strict quality control on the data obtained from seismic records and utilized for the inversion calculation. According to the preprocessing results, it is recommended to exclude the bubble pulses and their surface reflections, which are unstable and act as noise, from the estimated source wavelet applied to the inversion calculation. The calculation results show a significant level of directional variation in the acoustic energy radiated from the sparker source, and this variation should be considered in the calculation of seafloor reflectivity. In this work, the seafloor reflectivity is calibrated with relatively stable calculated values that correspond to known types of sediment, and the directivity constant of a sparker source is estimated (≈ 0.2), which is defined as the amplitude ratio between horizontally propagating seismic waves and vertically propagating seismic waves. The resulting relationship between the seafloor reflectivity and the sediment type is consistent with those of previous research, indicating the feasibility of our procedure. [ABSTRACT FROM AUTHOR]

Hybrid electrocatalysts derived from surface self-reconstruction during reaction processes can facilitate charge transfer between different phases and nanostructures by their unique interfaces. Herein, amorphous/crystalline hybrid iron disulfide obtained by self-reconstruction is developed for the first time for the oxygen evolution reaction (OER). The amorphous/crystalline hybrid FeS2 catalyst exhibited a high OER activity with an overpotential of only 189.5 mV (IR-corrected) to deliver 10 mA cm−2 in 1.0 M KOH, which was superior to that of the commercial RuO2. Notably, in the two-electrode system with the amorphous/crystalline hybrid FeS2 as the anode electrocatalyst and Pt/C as the cathode, the catalytic activity towards the overall water splitting was enhanced with a voltage of only 1.43 V at 10 mA cm−2. The phase, composition and surface structure were changed greatly before and after the reaction. All these surface reconstructions after the OER reaction may play significant roles in the high electronic catalytic efficiency. Therefore, the study of the surface reconstruction of catalysts during the reaction process is very important for the structure-performance relationship and the design of efficient hybrid electrocatalysts. [ABSTRACT FROM AUTHOR]

FeS 2 without dopants often exhibits poor oxygen evolution reaction (OER) performance, and development of FeS 2 with excellent performance for OER is still a challenge. In this study, uniform FeS 2 microspheres were synthesized and supported on Ni foam (NF), showing excellent OER activity with a low overpotential of 170 mV at 10 mA/cm2 in 1.0 M KOH electrolyte, superior to NF, other FeS 2 on NF and most of Fe-containing non-noble metal OER catalysts in the existing literature (ranked top 4) under the same test conditions. The revealing of catalyst reconstruction during OER is essential for understanding the real active sites, but studies on FeS 2 reconstruction are rare. Herein, reconstruction of FeS 2 microsphere to core-shell FeS 2 @FeOOH during OER was observed using TEM, SEM, XRD, XPS and Raman spectroscopy. The special core-shell FeS 2 @FeOOH structure benefited the OER performance. This research has significance for the understanding and rational design of FeS 2 catalyst for OER. [Display omitted] • FeS 2 microspheres supported on Ni foam show excellent OER activity. • Reconstruction of FeS 2 microsphere to core-shell FeS 2 @FeOOH after OER was observed. • The special core-shell FeS 2 @FeOOH structure benefited OER. [ABSTRACT FROM AUTHOR]

The synergistic effect and unique interfacial structure of ternary transition metal (Co, Ni, Fe) sulfides are significant in improving the catalytic performance of oxygen evolution reaction (OER). Herein, the ultrathin Co 0.3 Ni 0.3 Fe 0.2 S ternary sulfide nanoparticles (Co 0.3 Ni 0.3 Fe 0.2 S NPs) anchored in carbon bubble structure with rich pore structures (Co 0.3 Ni 0.3 Fe 0.2 S NPs/C) were firstly constructed via a cost-effective and general solid-phase synthesis strategy. Co 0.3 Ni 0.3 Fe 0.2 S NPs/C has a crystalline structure of Co 1−x S, accompanying the shift of diffraction peaks, which indicate the doping of nickel and iron atoms into Co 1−x S lattice. Co 0.3 Ni 0.3 Fe 0.2 S NPs/C catalyst has good OER activity with a low overpotential of 322 mV at 100 mA cm−2 in 1.0 M KOH electrolyte, superior to single metal sulfide synthesized at the same conditions. More importantly, the Co 0.3 Ni 0.3 Fe 0.2 S NPs/C catalyst possesses excellent stability with a low current density decrease in the continuous 336 h I-t test. The good catalytic intrinsic activity may originate from the synergistic effect among the highly exposed Fe, Co, and Ni sulfide grown on the porous carbon bubbles and the unique reconstruction structure formed during the OER process. This work provides some reference significance for the systematic study of the synergistic effects between multicomponents and the relationship between interfacial modulation and OER. • Ternary sulfide nanoparticles anchored in carbon bubble structures with rich pore structures were prepared. • The synergistic effect and interfacial reconstructed structure of Co 0.3 Ni 0.3 Fe 0.2 S NPs/C favor enhancing OER activity. [ABSTRACT FROM AUTHOR]

At present, developing new organic–inorganic hybrid materials (OIHM) and studying their photoelectric properties is an important research field. In this work, the OIHM (CH3NH3)2HgCl4 (MA2HgCl4) single crystal and thin film are prepared. The results show that the crystal structure of MA2HgCl4 has a monoclinic crystal system with P21/c (14) space group (unit cell dimensions 7.776 × 12.917 × 10.993 Å, 90.00 × 96.366 × 90.00) by solving the single crystal diffraction data. The band gap of MA2HgCl4 is calculated to be approximately 3.21 eV. To the best of our knowledge, this is the first study on MA2HgCl4 for optoelectronic application. The photodetector based on MA2HgCl4 thin film is highly selective for ultraviolet (UV) light (369 nm), and has a poor response for visible light. The electrochemical impedance spectrum shows that the impedance value (2 kΩ) of the device under 369 nm UV light is four magnitudes lower than that (107 Ω) under dark. Thus, MA2HgCl4 has the nature of a photoconductor. The density functional theory indicates that the valence band maximum (VBM) of MA2HgCl4 is mainly derived from Cl‐3p state, Hg‐5d state and organic CH3NH3+ state also participate in the formation of the VBM band. The electron states of VBM and the conduction band minimum of MA2HgCl4 come from inorganic HgCl42− clusters. [ABSTRACT FROM AUTHOR]

• VC–MC is prepared as bifunctional electrode for DSC and supercapacitor. • The VC–MC shows higher activity behavior than VC and MC. • VC–MC is a potential electrode for a self-powered integrated electronics. Vanadium carbide embedded in mesoporous carbon (VC–MC) is prepared using an in-situ synthesis method as hybrid electrode for supercapacitor. The electrochemical performance of the VC and VC–MC electrodes are analyzed and compared through a combination of cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy measurements in 1 M H 2 SO 4 aqueous electrolyte. The introduced mesoporous structure of the hybrid electrode provides optimized conducting pathways for electrons and protons, thus improving the capacitive performance of VC–MC electrode compared to pristine VC electrode. The synthesized VC–MC electrode achieves a specific capacitance up to 191.2 F g−1, which is significantly higher than the pristine VC electrode (95.6 F g−1). Moreover, the VC–MC hybrid electrode exhibits an excellent cycle performance with 89.5% capacitance retention after 10,000 charge–discharge cycles, considerably higher than the pristine VC electrode. Apparently, the VC–MC hybrid electrode which shows desirable capacitive performance, excellent stability and enhanced electrochemical properties can be attributable to the combination of the advantages possessed by MC and VC. Moreover, VC–MC was applied as counter electrode in flexible dye-sensitized solar cell which generate power conversion efficiencies of 6.50%, much higher than those of the devices using VC and MC counter electrodes (4.14% and 5.28%). [ABSTRACT FROM AUTHOR]

Developing highly effective and stable counter electrode (CE) materials to replace rare and expensive noble metals for dye‐sensitized and perovskite solar cells (DSC and PSC) is a research hotspot. Carbon materials are identified as the most qualified noble metal‐free CEs for the commercialization of the two photovoltaic devices due to their merits of low cost, excellent activity, and superior stability. Herein, carbonaceous CE materials are reviewed extensively with respect to the two devices. For DSC, a classified discussion according to the morphology is presented because electrode properties are closely related to the specific porosity or nanostructure of carbon materials. The pivotal factors influencing the catalytic behavior of carbon CEs are also discussed. For PSC, an overview of the new carbon CE materials is addressed comprehensively. Moreover, the modification techniques to improve the interfacial contact between the perovskite and carbon layers, aiming to enhance the photovoltaic performance, are also demonstrated. Finally, the development directions, main challenges, and coping approaches with respect to the carbon CE in DSC and PSC are stated. [ABSTRACT FROM AUTHOR]

• A bifilar optical fiber embedding technique for concrete dams is proposed. • An error correction method of DTS temperature measurement data is proposed. • Light intensity attenuation is calculated based on symmetrical measurement points. • Experiments and case study verify the reliability of the error correction method. Conventional distributed optical fiber systems employed for internal temperature sensing in concrete dams suffer from low survival rate, insufficient measurement data, and low-accuracy temperature measurements that are subject to large fluctuations. Therefore, the present study proposes a bifilar optical fiber embedding technique running within each of the concrete dam blocks forming a dam. The proposed fiber optic network design is based on multiple considerations, including the embedding requirements of optical fiber to ensure good system longevity, the requirements of internal temperature monitoring in concrete dams to ensure the capture of adequate monitoring data, and the temperature measurement principle of distributed temperature sensing (DTS) systems to develop effective error correction methods. In terms of error correction, the light intensity attenuation caused by transmission- and wavelength-related losses is calculated based on the symmetrical temperature measurement points of the primary and secondary strands of the embedded bifilar optical fiber in conjunction with error correction theory to correct for temperature measurement fluctuations and thereby ensure the capture of accurate and stable temperature measurement data. Experimental error correction test results demonstrate that the mean absolute error (MAE) and root mean squared error (RMSE) of the error corrected temperature data obtained under various temperature conditions are reduced by 0.28 °C and 0.34 °C, with fluctuations that are decreased by 53.4% and 52.4%, respectively. The results derived from an actual engineering application under construction demonstrate that the survival rate of the embedded bifilar optical fibers is 100%. In addition, the average MAE and RMSE values of the temperature data obtained by the DTS system during the first water cooling stage are reduced by 0.14 °C and 0.22 °C, and their fluctuations are decreased by 41.5% and 47.0%, respectively. These results verify the reliability and feasibility of the error correction method proposed in this paper, and the method is demonstrated to provide reliable technical support for obtaining stable and high-precision DTS temperature data in concrete dams. [ABSTRACT FROM AUTHOR]

The control of surface elements and nanostructures is one of the effective ways to design and synthesize high performance catalysts. Herein, we, for the first time, prepare FeS2 crystal lattices on WS2 nanosheets (FeS2 CL@WS2 NS) by solvothermal methods for the oxygen evolution reaction (OER). The FeS2 CLs effectively prevent the oxidation and aggregation of WS2 nanosheets and increase the electrochemically active surface area. The abundant surface defect in the FeS2 CL@WS2 NS electrocatalyst reduces the stress between the crystal lattices of FeS2 and that of WS2. The overpotential (260 mV) of the FeS2 CL@WS2 NS electrocatalyst for the OER at a current density of 10 mA cm−2 is superior to those of WS2 NS/Ni foam (310 mV) and IrO2/Ni foam (300 mV) in 1.0 M KOH solution. An electrochemical–kinetic study shows that the Tafel slope of 54 mV per decade for the FeS2 CL@WS2 NS electrocatalyst is lower than those of WS2 NS (102 mV per decade) and IrO2/Ni foam (77 mV per decade). In addition, the charge transport resistor (2.3 Ω) of the FeS2 CL@WS2 NS electrocatalyst for the OER is smaller than that of WS2 NS. These faster kinetic properties, in turn, explain the high catalytic activity of the FeS2 CL@WS2 NS electrocatalyst for the OER. The XPS and HRTEM results of the post stability sample confirm that Fe2+ and W4+ are oxidized after durability measurement. Thus, we think that the FeS2 CL@WS2 NS electrocatalyst is a promising candidate for efficient, low-cost, and stable non-noble-metal-based OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Metal halide salts have attracted widespread attention because of their good physical and chemical properties. In this study, lead‐free copper halide salt CsCuCl3 single crystals and photodetectors were prepared. According to the single crystal diffraction data, the CsCuCl3 single crystal has a hexagonal structure with P6522 (179) space group (7.2399 × 7.2399 × 18.3096 Å, 90.000 × 90.000 × 120.000). The crystal structure along the z‐axis is a double‐stranded helix structure. To the best of our knowledge, this is the first study on CsCuCl3 for optoelectronic applications. The CsCuCl3 photodetector exhibits high light response, sensitivity, and selectivity under 369 nm ultraviolet light and invalid response for visible light (511 nm). The device based on CsCuCl3 is highly selective for ultraviolet light (2.43 µA/mW) and feature high anti‐interference of visible light (0.0119 µA/mW). The device has the strongest selectivity at 369 nm light, which is 200 times higher than that at 511 nm. The results will be of interest for applications in photodetectors, LEDs, devices, and metal halide salts. [ABSTRACT FROM AUTHOR]

The performance of lead halogen perovskite is often closely related to its crystal structure. However, the chemical and optoelectronic properties of tetragonal phase single crystal MAPbCl3 (SC T-MAPbCl3) are rarely reported. In this study, we synthesized SC T-MAPbCl3 with the P4/mcc (124) space group by a modified inverse temperature crystallization (M-ITC) method. The twist angle of the Cl anion on the equatorial plane of the PbCl64− octahedron around the c-axis is 8.4°. The resistance (62 MΩ) of SC T-MAPbCl3 obviously decreased to 3 MΩ under 395 and 404 nm ultraviolet light. The photodetector based on SC T-MAPbCl3 under 3 V bias voltage exhibits high sensitivity (2.60 μA cm−2 under 1 W m−2 light intensity). The high selectivity of the device is in the ultraviolet region, rather than the visible region. [ABSTRACT FROM AUTHOR]

Photodetectors play a key role in the military, aerospace, communications, bio-imaging, etc. In this study, we fabricate photodetector devices based on (CH3NH3)2FeCuI4Cl2 (MA2FeCuI4Cl2) and (CH3NH3)2InCuI6 (MA2InCuI6) for the first time. We find that the device based on MA2InCuI6 is highly selective for ultraviolet light (880 nA mW−1) and shows high anti-interference for visible-light (20–50 nA mW−1). The electrochemical impedance results indicate that the value (480 ± 10 Ω) of the resistance based on the MA2InCuI6 photodetector device is much smaller than that (1 ± 0.001 MΩ) based on the MA2FeCuI4Cl2 photodetector device, which in turn proves the difference in photoelectric response. [ABSTRACT FROM AUTHOR]

Abstract V 2 O 3 @activated carbon (V 2 O 3 @C) composite catalysts with different mass ratios have successfully been fabricated using a facile one-step the reduction of ammonium vanadate (NH 4 VO 3) with AC in a high-temperature solid-state reaction. V 2 O 3 @C composites were further served as catalytic materials for counter electrodes (CEs) in encapsulation of dye sensitized solar cells (DSSCs). The morphology and microstructure of each V 2 O 3 @C composite were determined by scanning electron microscopy and X-ray diffraction. Cyclic voltammetry studies revealed that the V 2 O 3 @C composites showed a higher electrocatalytic activity than AC and V 2 O 3 for the reduction of triiodide ions. Electrochemical impedance spectroscopy and Tafel analysis data for the symmetrical cells indicated a lower charge transfer resistance and higher exchange current density for V 2 O 3 @C composite than AC and V 2 O 3. The experimental results showed that power conversion efficiencies (PCE) of 4.94, 5.55 and 5.32% were obtained for AC:NH 4 VO 3 mass ratios of 1:3, 2:3 and 4:3 as counter electrode toward the reduction of I 3 −/I− ions respectively, which were superior to higher than that of AC (2.10%) and V 2 O 3 (3.33%) electrode under the same conditions. The enhanced electrode performance can be ascribed to the combined effects of the relatively larger surface area and higher conductivity of V 2 O 3 @C composite catalysts. Graphical abstract Three V 2 O 3 @C CE-based DSSCs demonstrated PCE of 4.94, 5.55 and 5.32% were obtained for AC:NH 4 VO 3 mass ratios of 1:3, 2:3 and 4:3 respectively, which were superior to that of Pt (4.54%), AC (2.10%) and V 2 O 3 (3.33%) CE-based DSSCs from J-V curves. Unlabelled Image Highlights • V 2 O 3 @activated carbon composites as the counter electrode in DSSCs were prepared by a one-step direct pyrolysis reduction. • V 2 O 3 @ activated carbon with mass ratios of 2:3 exhibits higher PCE of 5.55% higher than others. • The hybrid V 2 O 3 @C obtains the potential for commercialization of noble-metal-free DSSCs. [ABSTRACT FROM AUTHOR]

Abstract Carbon molecular sieve is introduced as flexible supercapacitor electrode for the first time. The carbon molecular sieve electrode generates a specific capacitance of 108.0 F·g−1 and demonstrates an excellent stability with 98.5% preservation of its initial capacitance after 10,000 charging-discharging cycles. To further enhance the electrochemical performance, a flexible 3-D structured composite electrode is synthesized via an electrochemical polymerization method by depositing poly 3,4‑ethylenedioxythiophene film on the carbon molecular sieve surface, denoted as carbon molecular sieve@poly 3,4‑ethylenedioxythiophene. The specific capacitance of the composite electrode is up to 126.0 F·g−1, higher than both poly 3,4‑ethylenedioxythiophene (115.7 F·g−1) and carbon molecular sieve (108.0 F·g−1). Moreover, the flexible composite electrode preserves 96.0% of its initial capacitance after 10,000 charging-discharging cycles at 1.00 A·g−1. The superior performance of the composite electrode is attributed to the combined merits of the superior conductivity and excellent cycle stability of the carbon molecular sieve and 3-D porous network configuration of the poly 3,4‑ethylenedioxythiophene. [ABSTRACT FROM AUTHOR]

• Fe 1-x S nanocrystals/ultra-thin carbon nano-lamellar structure is fabricated. • The uniform dispersion of Fe 1-x S nanocrystals on the ultra-thin carbon layer favours the rapid complete reconfiguration. • The rapid reconfiguration creates new actual catalytic active species of amorphous iron-based oxide. • The reconfigured catalyst shows high OER activity and good stability in alkaline conditions. The surface reconfiguration of electrocatalysts during oxygen evolution reaction (OER) is much more important to reveal the actual catalytic active species, thus realizing the optimization of electrocatalyst activity. Herein, we demonstrate a simple strategy to achieve the complete electrochemical reconfiguration of Fe 1-x S nanocrystals/ultra-thin carbon (Fe 1-x S NCs/@ UT-C) nano-lamellar structure during the OER process. The uniform dispersion of Fe 1-x S nanocrystals on the ultra-thin carbon layer favors the rapid complete reconfiguration. Such rapid reconfiguration creates new actual catalytic active species of amorphous iron-based oxide transformed from Fe 1-x S, which is coupled with an ultra-thin carbon layer to facilitate the charge transfer of OER. More detailed, partly graphitization of the ultra-thin carbon layer not only affords to overcome the ohmic losses but also enhances the overall electrical conductivity and OER activity of the material. The Fe 1-x S NCs/@UT-C as pre-catalyst shows high OER activity with a low overpotential of only 303 mV at 100 mA cm−2 and a Tafel slope of 55 mV/dec. In addition, the reconfigured catalyst has good stability for 168 h in alkaline conditions. This work is beneficial to understand the reconfiguration of electrocatalysts and design high-efficiency nonprecious metal-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Petroleum geoscientists have been using cores and well logs to study source rocks and reservoirs, however, the inherent discontinuous nature of these data cannot account for horizontal heterogeneities. Modern exploitation requires better understanding of important source rocks and reservoirs at outcrop scale. Remote sensing of outcrops is becoming a first order tool for reservoir analog studies including horizontal heterogeneities. This work used ground-based hyperspectral imaging, terrestrial laser scanning (TLS), and high-resolution photography to study a roadcut of the Boone Formation at Bella Vista, northwest Arkansas, and developed an outcrop model for reservoir analog analyses. The petroliferous Boone Formation consists of fossiliferous limestones interbedded with chert of early Mississippian age. We used remote sensing techniques to identify rock types and to collect 3D geometrical data. Mixture tuned matched filtering classification of hyperspectral data show that the outcrop is mostly limestones with interbedded chert nodules. 1315 fractures were classified according to their strata-bounding relationships, among these, larger fractures are dominantly striking in ENE – WSW directions. Fracture extraction data show that chert holds more fractures than limestones, and both vertical and horizontal heterogeneities exist in chert nodule distribution. Utilizing ground-based remote sensing, we have assembled a virtual outcrop model to extract mineral composition as well as fracture data from the model. We inferred anisotropy in vertical fracture permeability based on the dominancy of fracture orientations, the preferential distribution of fractures and distribution of chert nodules. These data are beneficial in reservoir analogs to study rock mechanics and fluid flow, and to improve well performances. [ABSTRACT FROM AUTHOR]

Exploring Pt–free counter electrode catalysts for quasi–solid–state DSCs (QSDSCs) is significant for overcoming the high cost of Pt counter electrodes and their insufficient contact with the electrolyte. Herein, a two–dimensional (2D) layered MXene, V 2 C, is synthesized via a simple etching method as a counter electrode in QSDSCs. The impact of the etching time on the catalytic activity toward the regeneration of the I–/I 3 – redox couple in a quasi–solid–state electrolyte is investigated. After optimization, the V 2 C etched for 48 h shows a high catalytic activity caused by the constructed unique 2D lamellar structure, which can provide smooth diffusion channels for the penetration of the quasi–solid–state electrolyte to form sufficient contact between the V 2 C counter electrode and the electrolyte. As a result, the QSDSCs using the 2D layered V 2 C counter electrode generate a power conversion efficiency (PCE) of 7.48%. Moreover, the catalytic behavior of V 2 C is further improved by K+ intercalation, and the PCE value of the corresponding QSDSCs is enhanced to 8.30% under standard illumination (1.0 Sun) and to 10.19% under weak illumination (0.1 Sun). Meanwhile, the K+–intercalated V 2 C shows excellent stability, and 87.9% of the initial PCE of the device is retained after 1050 h in a durability test. This research is expected to provide meaningful support for the exploration of new counter electrode materials and the improvement of the contact between the counter electrode and quasi–solid–state electrolyte for the pursuit of high–performance and low–cost QSDSCs. [ABSTRACT FROM AUTHOR]

In this paper, the discrete-continuum mosaic (DCM) method is applied for predicting buckling of inner tubes of double-walled carbon nanotubes (DWNTs). The moving least squares (MLS) approximation is used for linking discrete atomic model and the corresponding continuum counterpart. Actual atomic positions are used as interaction points for the interlayer van der Waals (vdW) force of DWNTs, which can accurately capture the discreteness of non-bonded interactions, and a DCM contact model is constructed. A variationally consistent meshless computational scheme based on the DCM contact model is developed for simulating the buckling of inner tubes of DWNTs upon compression. Results show that both the lengths and radii of outer tubes can influence the buckling patterns of the corresponding inner tubes. The inner tubes of DWNTs with the interlayer spacing of 0.2034 nm have strongest buckling resistance for the case that the outer tubes are not extremely short. The local critical axial compression ratio of the inner tube increases with the lengths of the inner and outer tube increasing given that the interlayer spacing of a DWNT is less than 0.34 nm. • The discrete-continuum mosaic method is applied for predicting buckling of inner tubes of DWNTs. • The moving least squares approximation is used for linking the discrete atomic model and the continuum model. • The actual atomic positions are used as the interaction points for the van der Waals force. • A meshless computational scheme is built for simulating the buckling of inner tubes of DWNTs. [ABSTRACT FROM AUTHOR]

Active suspension has not been popularized for high energy consumption. To address this issue, this paper introduces the concept of a new kind of suspension. The linear motor is considered to be integrated into an adjustable shock absorber to form the hybrid active semiactive suspension (HASAS). To realize the superiority of HASAS, its energy consumption and regeneration mechanisms are revealed. And the system controller which is composed of linear quadratic regulator (LQR) controller, mode decision and switch controller, and the sliding mode control based thrust controller is developed. LQR controller is designed to maintain the suspension control objectives, while mode decision and switch controller decides the optimal damping level to tune motor thrust. The thrust controller ensures motor thrust tracking. An adjustable shock absorber with three regulating levels to be used in HASAS is trial produced and tested to obtain its working characteristics. Finally, simulation analysis is made with the experimental three damping characteristics. The impacts of adjustable damping on the motor force and energy consumption are investigated. Simulation results demonstrate the advantages of HASAS in energy conservation with various suspension control objectives. Even self-powered active control and energy regenerated to the power source can be realized. [ABSTRACT FROM AUTHOR]

This paper presents and compares two permanent magnet vernier (PMV) motors with fractional slot concentrated windings (FSCWs) and integral slot distributed windings (ISDWs). The ISDW PMV motor is newly proposed and optimized for a fair comparison with the existing FSCW one. The equations of back electromotive force of both motors are investigated and derived showing that the ISDW PMV motor has the potential to obtain higher torque capability. Also, their electromagnetic performances, such as torque capability, fault tolerance, loss, and efficiency, are calculated and compared by using the finite-element analysis. Then, the maximum power strategy for PMV motors operating at high speed is presented. The simulated results show that both motors possess excellent flux weakening capability. Finally, the effectiveness of the theoretical analysis is verified by the finite-element analysis results and experiments on a prototype FSCW PMV motor. [ABSTRACT FROM AUTHOR]

In this paper, a new linear wound-field flux reversal (LWFFR) machine for low-cost linear direct-drive applications is proposed. Similar to the conventional LWFFR machine, the proposed machine possesses the merit of a simple and compact long stator structure, a low cost, and a high flux adjustment ability. The novelty of the proposed machine is to be designed based on the magnetic gear effect. Hence, its force capability can be significantly improved without increasing the structural complexity and manufacturing cost. Meanwhile, the feasible combinations of mover pole and stator pole numbers for the LWFFR machines are extended, and thus provide a more flexible design choice. The operation principle and electromagnetic characteristic of a new optimal LWFFR machine are analyzed by means of the time-stepping finite-element method, verifying the effectiveness of the theoretical analysis. [ABSTRACT FROM AUTHOR]

While the CuBi2O4-based photocathode has emerged as an ideal candidate for photoelectrochemical water splitting, it is still far from its theoretical values due to poor charge carrier transport, poor electron–hole separation, and instability caused by self-photoelectric-corrosion with electrolytes. Establishing synthesis methods to produce a CuBi2O4 photocathode with sufficient cocatalyst sites would be highly beneficial for water splitting. Here, the platinum-enriched porous CuBi2O4 nanofiber (CuBi2O4/Pt) with uniform coverage and high surface area was prepared as a photocathode through an electrospinning and electrodeposition process for water splitting. The prepared photocathode material was composed of a CuBi2O4 nanofiber array, which has a freestanding porous structure, and the Pt nanoparticle is firmly embedded on the rough surface. The highly porous nanofiber structures allow the cocatalyst (Pt) better alignment on the surface of CuBi2O4, which can effectively suppress the electron–hole recombination at the electrolyte interface. The as-fabricated CuBi2O4 nanofiber has a tetragonal crystal structure, and its band gap was determined to be 1.8 eV. The self-supporting porous structure and electrocatalytic activity of Pt can effectively promote the separation of electron–hole pairs, thus obtaining high photocurrent density (0.21 mA/cm2 at 0.6 V vs. RHE) and incident photon-to-current conversion efficiency (IPCE, 4% at 380 nm). This work shows a new view for integrating an amount of Pt nanoparticles with CuBi2O4 nanofibers and demonstrates the synergistic effect of cocatalysts for future solar water splitting. [ABSTRACT FROM AUTHOR]

A composite catalyst of rosin carbon/Fe3O4 with marvellous morphology was synthesized and applied as a counter electrode (CE) in dye-sensitized solar cells (DSCs), demonstrating notable electrocatalytic activity for the reduction of I3−. Based on this CE, a high power conversion efficiency of 8.11% was achieved, comparable to that of the traditional Pt CE. [ABSTRACT FROM AUTHOR]

Pyridyl iodides were synthesized to serve as effective, economical, green and dual function additives for high efficiency and stable DSCs. Using commercial P25 as the photoanode, a high PCE of 7.81% was achieved with a pyridyl iodide-containing electrolyte. Meanwhile, DSCs based on our novel electrolytes demonstrated better stability. [ABSTRACT FROM AUTHOR]