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This article discusses the fault estimation (FE) and fault accommodation (FA) methods for fractional-order systems. First, two Lyapunov theorems of input-to-state practical stability are presented for fractional-order systems, based on which an adaptive FE/FA scheme is provided. Such a scheme ensures the faulty system is input-to-state practically stable (ISpS) with respect to estimation errors. Furthermore, new results are extended to fractional-order switched and interconnected systems: for the former, an FE/FA method is proposed which fully reveals the tradeoff between the value of the fractional order, each mode's dynamics, and switching law; for the latter, a cyclic-small-gain theorem of the fractional-order system is given under which both decentralized and distributed FE/FA methods are proposed.

To achieve higher coding efficiency, the latest Versatile Video Coding (VVC) standard adopts a series of new intra coding techniques, including the quadtree plus multi-type tree (QTMT), intra sub-partitions (ISP) and intra block copy (IBC). However, this makes the intra coding more complicated, as VVC needs to traverse all prediction modes and partition types of QTMT to find the optimal combination. In this paper, we propose a fast algorithm for VVC from two aspects of mode selection and prediction terminating to reduce coding complexity. For the mode selection, adaptive mode pruning (AMP) is proposed to remove non-promising modes. First, since the newly introduced modes (IBC and ISP) are not effective for all blocks, learning-based classifiers are designed to remove them intelligently. Second, for normal modes, an ensemble decision strategy is proposed to sort the candidate modes and increase the probability of being the optimal mode for the top few candidates; thus, we can remove redundant candidates more efficiently. In terms of prediction terminating, we find that different optimal modes of current depth level lead to different termination probabilities of remaining intra predictions. Therefore, mode-dependent termination (MDT) is proposed to select an appropriate model through the optimal mode and terminate unnecessary intra predictions of remaining depth levels. The proposed algorithm is implemented on VVC test model, and simulation results show that it can achieve 51%-53% time savings with only 0.93%-1.08% BDBR increases.

In this work, a novel approach to rapidly densify ceramic matrix composite was developed by combining ceramic and composite processing. Cf preform, which was injected and impregnated with slurries containing ZrSi2 and phenolic resin, was consolidated by spark plasma sintering at 1550 °C/50 MPa for 5 min. During densification, ZrSi2 and resin carbon converted to ZrC and SiC, newly formed particles were incorporated in the preform preferentially in the fiber randomly orientated layer. Although all the composites exhibit non-brittle fracture manner, their flexural strength and toughness only reach maximum in the sample with a carbon to ZrSi2 molar ratio of 3:1.

The growth of Zn dendrites and self-corrosion reaction during electrochemical cycling is a long-standing issue impeding the practical application of zinc-ion batteries. Although various surface engineering strategies have shown great promise in suppressing zinc dendrites, the protective layers unavoidably hinder Zn2+ diffusion, resulting in increased internal impedance/polarization. Therefore, constructing smart interface protective layers with fast Zn2+ transfer kinetics is highly desirable but remains a key challenge. Here, an Mg-Al layered double hydroxide (LDH)-based artificial solid electrolyte interface (SEI) with Zn-ion diffusion channels is proposed. The well-aligned interlayer channels in the Mg-Al LDH skeleton is proved to efficiently engineer the distribution of Zn2+ ions and facilitate Zn2+ diffusion between the electrode/electrolyte interface, thus giving rise to stable Zn deposition. Moreover, the mechanically robust Mg-Al LDH artificial SEI acts as an interfacial layer to constrain H2O-induced corrosion and hydrogen evolution reaction. Consequently, the Mg-Al LDH artificial SEI improves the Coulombic efficiency to 99.2% for more than 2000 cycles, and an ultralong lifespan of 1400 h has been achieved at 0.5 mA cm−2. Notably, the zinc-ion capacitors by pairing the Zn@LDH anode and high-loading active carbon cathode deliver outstanding cycling stability with a high capacity retention of 93.7% up to 10000 cycles at the high areal current density of 37.5 mA cm−2, portending the feasibility of practical applications.

This paper is concerned with the state estimation problem for an automatic guided vehicle (AGV). A novel set-membership filtering (SMF) scheme is presented to solve the state estimation problem in the trajectory tracking process of the AGV under the unknown-but-bounded (UBB) process and measurement noises. Different from some existing traditional filtering methods, such as Kalman filtering method and [Formula: see text] filtering method, the proposed SMF scheme is developed to provide state estimation sets rather than state estimation points for the system states to effectively deal with UBB noises and reduce the requirement of the sensor precision. Then, in order to obtain the state estimation ellipsoids containing the true states, a set-membership estimation algorithm is designed based on the AGV physical model and S-procedure technique. Finally, comparison examples are presented to illustrate the effectiveness of the proposed SMF scheme for an AGV state estimation problem in the present of the UBB noises.

Environmental investment prediction has attracted much attention in the last few years. However, there are still great challenges in investment prediction modeling, e.g., 1) effective environmental indicators must be accurately selected to avoid the curse of dimensionality; 2) effective environmental data must be reasonably selected to downsize the scale of historical data; 3) the higher interpretability and lower complexity of prediction models must be considered. To address the above three challenges, a new environmental investment prediction model using fuzzy rule-based system (FRBS), evidential reasoning (ER) approach, and subtractive clustering (SC) algorithm is proposed in the present work, called FRBS-ERSC. In this new model, the FRBS is the core component for the modeling of environmental investment prediction and therefore provides good interpretability and complexity to environmental managers. Meanwhile, the ER approach is used as an improvement technique of the FRBS to combine the strengths of different feature selection methods for better indicator selection, and the SC algorithm is used as another improvement technique of the FRBS to select effective environmental data. An empirical case of environmental investment prediction is studied based on data on 31 provinces in China ranged from 2005 to 2018. The experimental results show that the proposed FRBS-ERSC not only provides interpretable and scalable environmental investment prediction based on effective indicator selection and data selection, but also produces satisfactory accuracy compared to some existing models.

Sr(Ti0·3Fe0.7)O3-δ (STF) materials with satisfactory stability and no rare-metal elements have attracted increasing research interest as oxygen electrodes of solid oxide electrochemical cells. However, STF-based electrodes are still limited by their modest catalytic activities at low temperatures. This can be improved by A-site deficiency of STF-based materials; however, data related to the influence of A-site deficiency of perovskite-oxide-based materials on sintering behavior and electrochemical performance are still lacking. Herein, porous electrodes with different Srx (Ti0·3Fe0.7)O3-δ compositions (x = 0.85–1) were prepared. The effects of A-site cation deficiency ratios and sintering temperatures on the microstructures and electrochemical performance of the as-obtained STF electrodes were investigated. Electrochemical performance was improved for A-site deficient Srx (Ti0·3Fe0.7)O3-δ. For Sr0·9(Ti0·3Fe0.7)3-δ electrode material sintered at 1050 °C, the lowest polarization resistance measured at 700 °C was ~0.14 Ω⸳cm2 but increased at higher x values. At sintering temperatures above 1050 °C, the sintering diffusion occurred, where the electrolyte diffused through the deficient electrodes to form a dense layer at the electrode/electrolyte interface. On the other hand, although the presence of such diffused dense layer did not have significant effect on the electrochemical performance of the cells, it could be prevented by using lower sintering temperatures (≤1000 °C) to avoid possible negative effects on comprehensive performance. For the electrode obtained at x = 0.9 and sintered at 1000 °C, the overall polarization resistance was recorded as 0.099 Ω⸳cm2 at 700 °C. In sum, these findings look promising for future research.

The structure, surface topography and magnetic properties of LaCoO3 (LCO) thin films deposited epitaxially on the SrTiO3 substrates have been investigated in detail. The LCO thin films show a typical ferromagnetic-paramagnetic (FM-PM) phase transition at 78 K. Based on the measurements of isothermal magnetization around the Curie point, the magnetic entropy change (ΔSM) of LCO thin films under various applied magnetic fields were obtained. By utilizing scaling theory, all of the ΔSM curves can be re-scaled, confirming that the FM-PM phase transition is second-order magnetic phase transition. Moreover, the magnetic entropy change -ΔSM features a maximum around TC, whereas, power law fitting of - Δ S M max with H gives n = 0.9704, which is obviously deviating from the standard value n = 2/3 for the Landau mean field model. This indicates that the mean field theory cannot be used to explain the critical behavior of LCO thin films which implies that the critical behavior of LCO thin films may involve complex magnetic interactions. These interactions are correlated with a long-term puzzling finding in this system why its Curie point is always around 80 K regardless of the different fabrication methods and conditions used in the film growth.

The effects of the coefficient of friction and coefficient of restitution on the static packing characteristics of a polydisperse spherical pebble bed are numerically investigated using the discrete element method. Several important static packing characteristics under different coefficients of friction and restitution are presented and discussed. The results show that the coefficients of friction and restitution impose opposite effects on the packing heights and global packing factor. Neither the coefficient of friction nor restitution affected the oscillation width of the wall, whereas their effects are primarily reflected in the oscillation amplitude of the radial local packing factor and the axial local packing factor distribution at the top of the pebble bed. In both the contact force distribution and coordination number distribution, a left-shifted phenomenon appearing as the coefficient of friction occurred, and only the magnitude of the maximum frequency is affected when the coefficient of restitution changed from 0.1 to 0.9. In all simulation cases, the effects of the coefficients of friction and restitution are similar to that of cross-impact.

Transparent laser ceramics are the attractive gain medium for solid-state lasers. However, they have not been applied to the fiber lasers due to the difficulty of forming green fibers by traditional methods. In this study, a novel route combined aqueous gelcasting with capillary glass tube was designed to prepare Yb:YAG transparent ceramic fiber with a diameter of 1.0 mm and 43.0 mm in length for the first time. The slurry with high solid loading and low viscosity was smartly inhaled into the capillary glass tube to conquer the difficulty of casting. The green fibers without cracks and deformation had highly dense microstructure. The in-line transmittance of highly doped 15.0 at.% Yb:YAG transparent ceramic disc prepared from the same preparation conditions of Yb:YAG ceramic fiber was 80.0 % at 1064 nm. This study provides a novel route to prepare transparent ceramic fiber differing from extrusion processing, promoting the development of fiber laser.

The existing bearing temperature fault detection and early warning system has a high false alarm rate and insufficient early warning ability. For this reason, in this study, a method for detecting the abnormal bearing temperature of high-speed trains based on spatiotemporal fusion decision-making was proposed. First, the temperature characteristics of similar bearings were compared and analyzed with different spatial distributions. Then, a bearing abnormal temperature rise detection model based on the analytic hierarchy process (AHP) entropy method was proposed. Second, the temperature characteristics of the same bearings were compared and analyzed with different time distributions. A real-time prediction model of high-speed train bearing temperature anomalies based on Bi-directional Long Short-Term Memory (BILSTM) was proposed. Finally, the D-S evidence theory was used to combine the anomaly detection model based on the AHP entropy method and the anomaly detection model based on BILSTM real-time prediction. Through the comprehensive diagnosis and decision-making of high-speed train bearings from two dimensions of space and time, a more comprehensive and accurate anomaly detection model was realized. The experimental results showed that the spatiotemporal comparison fusion decision model successfully eliminated the misjudgment phenomenon of single-dimension model diagnosis and that it has good early warning ability.

Ti3C2 is the first member of two-dimensional (2D) transition metal carbide or carbonitride (MXene) with excellent photothermal effect in disease treatment on an animal model, which shows a potential prospect on clinical application. However, in-depth details on the biosafety of MXene were insufficient. Metabolomics approach has offered an excellent alternative with numerous bioinformation, which can demonstrate the response of an organism to external stimuli at the molecular level. In this study, two different concentrations (100 and 500 mg/L) of MXene were used to treat human umbilical vein endothelial cells (HUVECs), and under both conditions, no obvious acute cytotoxicity was observed by cell proliferation and apoptosis measurement. We used a platform combining LC-MS/MS, GC-MS, and bioinformatics to analyze the changes of HUVECs metabolome after treatment with different concentrations of MXene, and the results indicated that —high concentrations (500 mg/L) of MXene can cause significant changes in the energy metabolism of HUVECs, showing obvious inhibition of tricarboxylic acid (TCA) cycle with the enhancement of glycolysis, fatty acid biosynthesis, and lipid accumulation, which are closely related to the functional disorder of mitochondria. The metabolomics results of the novel MXene-cell system extend the knowledge on the biological effect of MXene, possibly enabling technological innovations and material modifications.

Zirconia microspheres with high sphericity and hardness were successfully massively produced through a cost-effective spray granulation method by using an optimized slurry with high solid content and low viscosity which was formulated with a mixed dispersant. The influence of slurry solid content, binder addition as well as drying temperature on the shape and size of the sintered microspheres were studied. Furthermore, the formation mechanism of different granulated particles was analyzed based on the illustrated migration processes in the ZrO2 droplets with different contents of water and additives. Under the optimized conditions, the sintered ZrO2 spheres with tetragonal phase exhibit high sphericity with highest nano-hardness of 9.5 GPa, indicating it is possible to be used in the engineering fields. Such spray granulation method could directly serve for the industrial production of zirconia and other ceramic materials since it is a stable process with high yield, good granulating quality and strong controllability.

Due to the low chemical activity and large detonation cell size, methane-air continuous rotating detonation (CRD) is hard to be realized in a traditional small annular chamber without extra additives. In order to investigate the characteristics of methane-air CRD wave in a small chamber, three hollow chambers with Laval nozzles are adopted in this research. The methane-air CRD can be realized in a quite small chamber (diameter of 80 mm) under very particular condition. The operating range enlarges with the increase of chamber diameter. The CRD wave propagation frequencies vary apparently with chamber diameter while the propagation velocities stay in a quite narrow range of 1744–1812 m/s, and the relative deviation is within 4%. The CRD wave propagation process is very stable, and the propagation velocity accounts for 99% of the theoretical C-J velocity in the chosen test. Optical observation results illustrate that the reduction in chamber diameter or increase in nozzle contraction ratio will lead to CRD deterioration. By comparing the frequencies of high-frequency pressure and optical observations, the coupling of inducing shock wave and combustion flame is proved quantitatively.

Machining of NiTi alloys is a challenging task owing to their inherent material properties and unique phase transformation-based behaviors. In this study, the effects of super-elasticity on the machinability of room-temperature austenitic NiTi alloy were investigated through turning experiments conducted at various cutting speeds under the non-preheating and preheating conditions. As a result, the workpiece exhibited an unavoidable super-elastic shape recovery and underwent a partial phase transformation because the temperature of the workpiece had not exceeded the martensite desist temperature (Md) during machining under the non-preheating condition. The super-elastic recovery of the workpiece resulted in the deterioration of the machinability, through the decrease in the dimension accuracy, increase in the cutting resistance, and shortening of the tool life. The deterioration of the machinability caused by super-elasticity was intensified with the increase in the cutting speed. However, an excessively low cutting speed of 10 m/min induced severe built-up edge deposition on the machined surface. When the workpiece was preheated to a temperature above the Md, the dimension accuracy was enhanced, the cutting resistance decreased and the tool life was prolonged owing to the elimination of the effects of the super-elasticity. Therefore, machining at moderate cutting speeds in the range of 25 to 50 m/min after preheating the workpiece to a temperature above the Md can improves the machinability of room-temperature austenitic NiTi alloy.

Two new supramolecular polyoxmetalates were synthesized from 1, 4-bis[4-nitrile-pyridine)-N-methylene]phenyldibromide (L1) and 1, 2-bis[4-nitrile-pyridine)-N-methylene]phenyldibromide (L2) and (NH4)6Mo7–O24·4H2O under hydrothermal conditions. They are named p-[C20H18N2O4][Mo8O26] 0.5·H2O (1) and o-[C20H18N2O4][Mo8O26] ċ 0.5·H2O (2) respectively. The structures have been confirmed through single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra. The adsorption test of compound 1 and compound 2 in organic dyes were carried out. It was found that compound 1 had a good adsorption effect on methylene blue (MB) and rhodamine B (RhB). The adsorption effect of compound 2 on MB is stronger than that of compound 1.

Principal component active control is of great interest in recent times because of its extensive use in vibration and noise reduction applications. Existing analyses for such control systems mainly focus on simplified representations of the closed-loop system to obtain robust stability conditions, but they exclude key practical considerations, such as open-loop dynamics, periodic time-varying effects generated by the transformations between the time-domain harmonic signals and the estimation of their Fourier coefficients, multirate issues caused by the plant and the controller operating at different sampling rates, modeling errors, and particular ways of scaling the control actions. The contribution of this work is to include all the afore-mentioned effects to provide more accurate robustness conditions, which complement existing controller tuning procedures. The robustness analysis is conducted by first exploiting the time-lifting method to reformulate the linear-periodic-time-variant part of the discrete-time system into an equivalent linear-time-invariant representation. Then using the theoretical tool of integral quadratic constraints, standard forms of plant uncertainty and scaling of the control actions are incorporated. A vibration control example based on the Airbus EC-145 helicopter main rotor with On-Blade actuators is included to demonstrate the benefits of the contributions. The proposed design results are benchmarked against the mixed-sensitivity $\mathcal {H}_\infty $ method, highlighting strengths, and weaknesses by each approach for this particular application.

Background China is one of the world’s fastest-aging countries. Population aging and social-economic development show close relations. This study aims to illustrate the spatial-temporal distribution and movement of gravity centers of population aging and social-economic factors and thier spatial interaction across the provinces in China. Methods Factors of elderly population rate (EPR), elderly dependency ratio (EDR), per capita gross regional product (GRPpc), and urban population rate (UPR) were collected. Distribution patterns were detected by using global spatial autocorrelation, Kernel density estimation, and coefficient of variation. Further, Arc GIS software was used to find the gravity centers and their movement trends yearly from 2002 to 2018. The spatial interaction between the variables was investigated based on bivariate spatial autocorrelation analysis. Results The results showed a larger variety of global spatial autocorrelation indexed by Moran’s I and stable trends of dispersion degree without obvious convergence in EPR and EDR. Furthermore, the gravity centers of the proportion of EPR and EDR moved northeastward. In contrast, the economic and urbanization factors showed a southwestward movement, which exhibited an reverse trend compared to population aging indicators. Moreover, the movement rates of EPR and EDR (15.12 and 18.75 km/year, respectively) were higher than that of GRPpc (13.79 km/year) and UPR (6.89 km/year) annually during the study period. Further, the bivariate spatial autocorrelation variation is in line with the movement trends of gravity centers which showed a polarization trend of population aging and social-economic factors that the difference between southwest and northeast directions and exhibited a tendency to expand in China. Conclusions In sum, our findings revealed the difference in spatio-temporal distribution and variation between population aging and social-economic factors in China. It further indicates that the opposite movements of gravity centers and the change of the BiLISA in space which may result in the increase of the economic burden of the elderly care in northern China. Hence, future development policy should focus on the social-economic growth and distribution of old-aged supporting resources, especially in northern China.

Capturing the underlying semantic relationships of sentences is helpful for machine translation. Variational neural machine translation approaches provide an effective way to model the uncertain underlying semantics in languages by introducing latent variables. Multitask learning is applied in multimodal machine translation to integrate multimodal data. However, these approaches usually lack a strong interpretation in utilizing out-of-text information in machine translation tasks. In this paper, we propose a novel architecture-free multimodal translation model, called variational multimodal machine translation (VMMT), under the variational framework which can model the uncertainty in languages caused by ambiguity through utilizing visual and textual information. In addition, the proposed model can eliminate the discrepancy between training and prediction in the existing variational translation models by constructing encoders only relying on source data. More importantly, the proposed multimodal translation model is designed as multitask learning in which the shared semantic representation for different modes is learned and the gap among semantic representation from various modes is reduced by incorporating additional constraints. Moreover, the information bottleneck theory is adopted in our variational encoder–decoder model, which helps the encoder to filter redundancy and the decoder to concentrate on useful information. Experiments on multimodal machine translation demonstrate that the proposed model is competitive.

In order to realize the resource and sustainable utilization of quartz sand waste discarded from the mineral processing, Mg2+-doped cobalt blue composite pigments are prepared based on quartz sand via co-precipitation method followed by high-temperature crystallization. The obtained composite pigments are characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and magic angle spinning nuclear magnetic resonance. The results indicate that the incorporation of Mg2+ ion and quartz sand improves the color properties and decreases the production cost of composite pigments, and the color can be facilely adjusted by controlling the added amount of Mg2+. The optimal color properties are obtained as the molar ratio of Mg2+ to Co2+ is 6:4, and Mg2+ enters into the crystal lattice and occupies the tetrahedral sites of spinel cobalt blue. Therefore, this study is expected to develop feasible approach for the resource and sustainable utilization of quartz sand waste, and fabrication of low-cost bright cobalt blue composite pigments as well.

Active Lamb wave detection is an effective and simple monitoring method for structural health monitoring (SHM). Piezoelectric lead zirconate titanate (PZT) ceramics are most commonly used as transducers to excite and receive Lamb wave. However, due to their hardness, thickness and brittleness, PZT ceramics are severely limited in detecting damage on curved surface structures. Herein, we report that flexible PZT film sensor is an excellent candidate for receiving Lamb wave used in Lamb wave-based SHM of aircraft. An improved piezoelectric coefficient d33 (~130 pm V−1) is obtained in epitaxial PZT films grown on flexible inorganic mica substrates via van der Waals heteroepitaxy. Superior stable ferroelectricity and piezoelectricity retain in flexible PZT film after bending 104 cycles under a radius of 8 mm. As proven by experiment and simulation, flexible PZT film is demonstrated as an ultrasonic sensor with high sensitivity to be bonded on the curved aluminum plate for Lamb wave-based damage monitoring. Our work demonstrates that flexible PZT films have enormous potential for real-time light-weight and high-sensitivity receiver sensors for the SHM of aging aircraft.

Insufficient vascularization of grafts often leads to delayed tissue ingrowth and impaired tissue function in tissue engineering. The surface topography of grafts plays critical roles in angiogenesis. In the present study, we prepared silk fibroin (SF)-based microtopography films with the number of convex dots ranging from 37 to 4835/mm2. The convex dot-featured topography surfaces were characterized by scanning electron microscopy, a Profilm3D optical profilometer, atomic force microscopy, and a contact angle goniometer. The effect of microtopographic films on the proliferation, adhesion, and expression of angiogenic factors of human umbilical vein endothelial cells (HUVECs) was investigated. Our results demonstrated that the SF film surface with 2899 convex dots/mm2 significantly enhanced adhesion, viability, and levels of vascular endothelial growth factors and basic fibroblast growth factors of HUVECs and significantly downregulated the level of α-SMA in human aortic smooth muscle cells, indicating that the microtopographic films could promote angiogenesis. Furthermore, in vitro results showed that HUVEC proliferation was positively correlated with yes-associated protein (YAP) activation, suggesting that the enhanced angiogenesis was mediated via the YAP pathway. Finally, mice subcutaneous embedding model results indicated that the SF film surface with 2899 convex dots/mm2 could significantly enhance angiogenesis in vivo. Altogether, our results showed that the SF film surface with 2899 convex dots/mm2 promoted the angiogenesis of HUVECs and offered a novel angiogenesis-promoting strategy of implant surface design for tissue engineering.

This article addresses the issues of model reduction and actuator/sensor placement for flexible spacecraft with plant, actuator, and sensor faults. First, the sensitivity of controllability and observability with respect to faults is analyzed; Second, instead of a complete redesign of balanced truncation, a fault tolerant truncation method is proposed by estimating the bounds of Hankel singular value of faulty spacecraft and is fully based on the original balanced truncation structure; Third, a reconfiguration scheme of actuator/sensor placement is developed based on the reduced-order faulty flexible spacecraft.

This paper addresses the fault-tolerant control (FTC) issue for a class of multilayer interconnected nonlinear systems by using the inclusion principle. First, an overlapping decomposition method is proposed that expands the original interconnected system into a new one where each layer is not overlapped with each other. Second, for such an expanded system, the coupling effects among multiple layers are analyzed by using cyclic-small-gain theorem, and FTC schemes based on layer cooperation are further developed. Finally, the control designed for the expanded system is contracted back to the original interconnected system to achieve its FTC goal. An example of multiple pendulums is taken to illustrate the efficiency and applicability of the obtained theoretical results.

Although metal silicates are considered as the promising electrode materials for lithium-ion batteries, metal silicate-based materials suffer from inadequate cycling performance and dimensional unreliability evoked by the large volume changes during cycling, which hinders their practical applications. In principle, the poor electrochemical kinetics during the redox reactions of metal silicates is originated from the instinct structure. Hence, the precise and delicate ability to construct hetero-layers to tailor intercalation reaction remains elusive. Herein, a facile strategy of designing and constructing heterostructure in a cobalt-copper silicates nano-architecture (CNT@CoCuSiOx) with synergistic interaction between cobalt silicate (Co2SiO4) with copper silicate (CuSiO3) on the surface of carbon nanotubes (CNTs). Moreover, Co2SiO4/CuSiO3 heterojunction with unbalanced charge distributions that rooted from in-situ generation on CNTs by a facile one-step hydrothermal process, can efficiently tailor the electrochemical activities of Cu3+/Cu2+ and Co3+/Co2+ redox reactions by elevating transfer of electrons and delivering the heterointerface effect. The tough and conductive nanostructure of CNTs basement facilitate the ion diffusion and improve the rate capability. The heterostructure-incorporated CNT@CoCuSiOx-(2/1) exhibits not only outstanding electrochemical capacity (545 mAh g−1 at 0.1 A g−1), superior ion/electron transmission efficiency but also robust cycling performance (516 mAh g−1 after 900 cycles at 0.5 A g−1 and an excellent capacity retention rate of 95%). Beyond energy storage, our delicate methodology in manipulating the electrochemical behavior of metal silicates opens up a critical insight into rational fabrication of next-generation anodes for lithium-ion battery.

Up to now, micro milling has been recognized as the most promising technique to mitigate the surface damage of large-aperture KDP crystal used in laser fusion facility. However, there are quantities of damages on the surface of large-aperture KDP crystal to be mitigated. Furthermore, the efficiency and accuracy of manual tool setting is relatively low, and it is easy to damage KDP crystal surface due to mis-operation. Therefore, an automatic tool setting technology for KDP crystal surface damage mitigation based on machine vision is proposed in this research. The automatic tool setting includes fast pre tool setting achieved by image ranging and final tool setting achieved by micro-chip detection. In the process of fast pre tool setting, real-time image of the micro milling cutter is obtained, and the distance between the tool tip and the KDP crystal surface is obtained by image ranging. Finally, the tool tip is quickly positioned 20 μm away from the KDP crystal surface. In the process of final tool setting, the micro milling cutter is retreated to a distance of about 50 μm away from the KDP crystal surface before detecting micro-chips. Therefore, the micro-chips covered by the micro milling cutter will be exposed and appear in the view field of microscope, so as to improve the micro-chip recognition rate. The results showed that the total time of automatic tool setting is 130 s, and the accuracy of automatic tool setting is better than 1.359 μm. Compared with manual tool setting, the automatic tool setting based on machine vision proposed in this research improves the safety, efficiency, and accuracy of independently developed mitigation system for KDP crystal surface damage.

Enabling materials with distinct features toward achieving high-performance energy storage devices is of huge importance but highly challenging. Commercial carbon cloth (CC), because of its appealing chemical and mechanical properties, has been proven to be an excellent conductive substrate for active electrode materials. However, its performance is notably poor when directly used as an electrode in energy storage, due to its low theoretical capacity and surface area. Herein, we successfully endow the CC with enhanced storage capacity via formation of a π-π stacking interaction by integrating electrochemically activated CC (denoted CC/ACC) with biomass-derived carbon (BMDC) (denoted π-CC/ECC@BMDC). The π-CC/ECC@BMDC electrode displays excellent storage performance with a high capacity of 2.53 mAh cm-2 under 0.2 mA cm-2 when used as anode material for lithium ion batteries (LIBs). Due to the induction energy, the negatively charged molecules of the CC/ACC functional groups interact with the BMDC during carbonization, creating the π-π stacking interaction. Based on first-principles calculations, the structural design of the tri-layer carbon enables the movement of electrons around the π-π stacking interaction, which significantly facilitates rapid transportation of electrons, creates three-dimensional (3D) ion tunnels for fast transportation of ions, and improves the electrode's mechanical and electronic properties.

Due to creating a passivated solid electrolyte interphase (SEI), high concentration (HC) electrolytes demonstrate peculiar physicochemical properties and outstanding electrochemical performance. However, the structures of such SEI remains far from clear. In this work, a hybrid abinitio and reactive molecular dynamics (HAIR) scheme is employed to investigate the concentration effect of SEI formation by simulating the reductive degradation reactions of lithium bis(fluorosulfonyl)imide (LiFSI) in 1,3 dioxalane (DOL) electrolytes at concentrations of 1 M, 4 M, and 10 M. The efficient HAIR scheme allows the simulations to reach 1 ns to predict electrolytes’ deep products at different concentrations. The simulation findings show that the most critical distinction between HC and its low concentration (LC) analogue is that anion decomposition in HC is much more incomplete when only S–F breaking is observed. These insights are important for the future development of advanced electrolytes by rational design of electrolytes.

In this study, the effect of axial heat conduction on thermal performance in a zigzag channel printed circuit heat exchanger (PCHE) with supercritical liquefied natural gas as the working fluid is studied by a numerical method under different conditions. The influence factors include Reynolds number, operating pressure, inlet temperatures of the cold side, and wall thermal conductivity. The results indicate that the axial heat conduction can greatly affect the thermal performance of the PCHE at low Reynolds numbers but decrease it at high Reynolds numbers for different working conditions. At the same average Reynolds number, the thermal performance of the PCHE decreases as the pressure increases, and the inlet temperature of 195 K provides the best thermal performance while the inlet temperature of 220 K is the worst among the three different inlet temperatures of the cold side. Furthermore, the reduction of wall thermal conductivity can improve the thermal performance of the PCHE due to the influence of axial heat conduction in the separation wall.

There is a broad consensus that subduction of the Paleo-Pacific oceanic plate has caused extensive magmatism, lithospheric deformation, and metal mineralization in the eastern margin of the Eurasia...

As an important functional thin-film material in the field of electronic information, high-purity titanium (Ti) is widely used in different industries, such as integrated circuits, flat-panel displays and solar energy, indicating the importance of further research on Ti targets. Herein, a titanium target is placed in a UDP-650 closed-field nonequilibrium magnetron sputtering ion coating machine for deep etching to form racetrack grooves, and different positions of etching grooves are analyzed to understand the target etched behavior. The sputtering-induced etching of the Ti target, from shallow to deep regions, changes from the preferential sputtering of scratches and other defects in the edge area to the surface sputtering pits, with discontinuous distribution and uneven size, to grain boundary sputtering and, finally, to closely packed grain surface sputtering. The etching behavior of different regions exhibits different characteristics, mainly showing selective sputtering. The surface roughness of the sputtered area initially increases with the increase of sputtering depth and plasma density, followed by a slight decrease. Moreover, different degrees of incomplete recrystallization occur in different sputtering areas due to the uneven distribution of plasma on the target surface. The grain size increased from the transition area between sputtering and non-sputtering (112 μm) to the deepest sputtering area (139 μm). Moreover, the relationship between the cross-sectional grain size and sputter surface roughness renders a correlation coefficient of 0.802, indicating a strong influence of grain size on surface roughness. Therefore, it is of utmost importance to refine grains and increase the sputtering yield of the target as well as reduce the surface roughness of the target after etching to obtain a high-quality thin film.

This paper addresses a fault accommodation issue for flexible hypersonic vehicles by the static output feedback. Firstly, a longitudinal dynamics for hypersonic vehicles is established in the ODE-b...

To probe the coupling effect of the electron and Li ion conductivities in Ni-rich layered materials (LiNi0.8Co0.15Al0.05O2, NCA), lithium lanthanum titanate (LLTO) nanofiber and carbon-coated LLTO fiber (LLTO@C) materials were introduced to polyvinylidene difluoride in a cathode. The enhancement of the conductivity was indicated by the suppressed impedance and polarization. At 1 and 5 C, the cathodes with coupling conductive paths had a more stable cycling performance. The coupling mechanism was analyzed based on the chemical state and structure evolution of NCA after cycling for 200 cycles at 5 C. In the pristine cathode, the propagation of lattice damaged regions, which consist of high-density edge-dislocation walls, destroyed the bulk integrity of NCA. In addition, the formation of a rock-salt phase on the surface of NCA caused a capacity loss. In contrast, in the LLTO@C modified cathode, although the formation of dislocation-driven atomic lattice broken regions and cation mixing occurred, they were limited to a scale of several atoms, which retarded the generation of the rock-salt phase and resulted in a pre-eminent capacity retention. Only NiO phase “pitting” occurred. A mechanism based on the synergistic transport of Li ions and electrons was proposed.

A finite element model of temperature field for plasma spraying preset MCrAlY coating during laser cladding was constructed using ANSYS parametric design language (APDL) in accordance to characteristics of preset laser cladding. Influencing laws of laser cladding parameters on temperature field were analyzed. Results show that laser power influences temperature field of cladding samples more than laser scanning speed. Experimental results agree well with simulation results, which prove the accuracy and reliability of the constructed calculation model of temperature field. Heating and cooling laws in the laser cladding process could be mastered through this calculation model. Research conclusions provide some references to optimization parameters in preparing high-performance laser cladding coatings.

Probabilistic Fault Recoverability (FR) property reveals the capability of a system to accommodate faults under admissible input energy constraints in the sense of satisfactory probability. Motivated by the idea of probabilistic control methods, a class of admissible probability density functions is designed for detailed description of fault parameters, under which several probabilistic FR conditions are established. This significantly enlarges the range of recoverable faults obtained from the deterministic FR analysis. The tradeoffs between the risk of performance degradation and this increased recoverability margin are exactly achieved by allowing a small risk of FR violation. This paper analyzes the probability FR of dynamic systems with switching and interconnection characteristics, and applies the new results to several aircraft models including single longitudinal aircraft dynamic, Highly Maneuverable Technology (HiMAT) vehicle and meta aircraft. Simulation results show the efficiency of the proposed methods based on the comparison between deterministic and probabilistic cases.

Helicopters are widely used in maritime Search and Rescue (SAR) missions. To ensure the success of SAR missions, search areas need to be carefully planned. With the development of computer technology and weather forecast technology, the survivors’ drift trajectories can be predicted more precisely, which strongly supports the planning of search areas for the rescue helicopter. However, the methods used to determine the search area based on the predicted drift trajectories are mainly derived from the continuous expansion of the area with the highest Probability of Containment (POC), which may lead to local optimal solutions and a decrease in the Probability of Success (POS), especially when there are several subareas with a high POC. To address this problem, this paper proposes a method based on a Minimum Bounding Rectangle and K-means clustering (MBRK). A silhouette coefficient is adopted to analyze the distribution of the survivors’ probable locations, which are divided into multiple clusters with K-means clustering. Then, probability maps are generated based on the minimum bounding rectangle of each cluster. By adding or subtracting one row or column of cells or shifting the planned search area, 12 search methods are used to generate the optimal search area starting from the cell with the highest POC in each probability map. Taking a real case as an example, the simulation experiment results show that the POS values obtained by the MBRK method are higher than those obtained by other methods, which proves that the MBRK method can effectively support the planning of search areas and that K-means clustering improves the POS of search plans.

The high energy density and suitable operating voltage make rechargeable lithium ion batteries (LIBs) promising candidates to replace such conventional energy storage devices as nonrechargeable batteries. However, the large-scale commercialization of LIBs is impeded significantly by the degradation of the electrolyte, which reacts with the highly reactive lithium metal anode. Future improvement of the battery performance requires a knowledge of the reaction mechanism that is responsible for the degradation and formation of the solid-electrolyte interphase (SEI). In this work, we develop a hybrid computational scheme, Hybrid ab initio molecular dynamics combined with reactive force fields, denoted HAIR, to accelerate Quantum Mechanics-based reaction dynamics (QM-MD or AIMD, for ab initio RD) simulations. The HAIR scheme extends the time scale accessible to AIMD by a factor of 10 times through interspersing reactive force field (ReaxFF) simulations between the AIMD parts. This enables simulations of the initial chemical reactions of SEI formation, which may take 1 ns, far too long for AIMD. We apply the HAIR method to the bis(trifluoromethanesulfonyl)imide (TFSI) electrolyte in 1,3-dioxolane (DOL) solvent at the Li metal electrode, demonstrating that HAIR reproduces the initial reactions of the electrolyte (decomposition of TFSI) previously observed in AIMD simulation while also capturing solvent reactions (DOL) that initiate by ring-opening to form such stable products as CO, CH2O, and C2H4, as observed experimentally. These results demonstrate that the HAIR scheme can significantly increase the time scale for reactive MD simulations while retaining the accuracy of AIMD simulations. This enables a full atomistic description of the formation and evolution of SEI.

Developing advanced electrocatalysts to convert CO2 into liquid fuels such as ethanol is critical for utilizing intermittent renewable energy. The formation of ethanol, however, is generally less f...

Increasing use of NiTi alloy products makes it very important to improve the cutting performance of this material. This study presents the effect of cutting speed on radial shape recovery of work material which is supposed to deteriorate the dimension accuracy in cutting process of super-elastic NiTi alloy. The shape recovery of work material was investigated at the beginning of cutting process, during the stable part of cutting process and after feed stops respectively utilizing a high-speed camera and a cutting force dynamometer in orthogonal cutting experiments at various cutting speeds. The mechanism of the shape recovery was investigated by analyzing the crystallization phase state of work material before and after cutting using XRD and measuring the temperature distributions on the end surface of work material during orthogonal cutting experiments using non-reversible temperature indicating paints correspondingly. Results show that at relatively low cutting speed, the temperature of work material near the cutting point did not exceed the threshold temperature of phase transformation, and thus work material generated obvious shape recovery throughout the whole cutting process due to the phase transformation. Increasing cutting speed could increase the temperature of work material; when cutting speed increased to 100 m/min, the temperature of work material near the cutting point exceeded the threshold temperature of phase transformation, thus work material did not generate obvious shape recovery because it could not undergo any form of phase transformation during the stable part of cutting process and after feed stops. Consequently, increasing cutting speed could be proposed as an approach to improve dimension accuracy by inhibiting shape recovery of work material in cutting process of NiTi alloy.

Seawater oxygen evolution is one of the promising energy conversion technologies for large-scale renewable energy storage. It requires efficient catalysts to accelerate the oxygen evolution reactio...

This study explored the effect of diamond content (0, 0.3, 0.6, and 0.9 wt%) onTi(C0.5,N0.5)-based cermets prepared via vacuum sintering with respect to their final mechanical properties and microstructures, characterized using X-ray diffractionand scanning electron microscopy. After liquid phase sintering, all cermets exhibited a ‘black core/grey rim'and partial ‘white core/grey rim'structure. The cermet with 0.6 wt% diamond exhibited optimal mechanical properties with a Vickers hardness of 1795 ± 32 H V, transverse rupture strength of 2026 ± 45 MPa, and plane strain fracture toughness of 12.95 ± 0.3 MPa m1/2. This is due to grain refinement and the uniformly distributed ‘white core/grey rim'grains. During the incipient liquid formation stage,a higher carbon activity arising due to diamond graphitization may shift the equilibrium towards the product, thereby yielding additional white cores due to the consumption of heavy elements in the binder. Excessive diamond introduction inhibited the dissolution of Ti(C0.5,N0.5) into the binder, resulting in fewer white cores.

For the airports worldwide, it is important to establish a "passenger integrity system" based on the basic information of passengers and their related credit system. Correspondingly, this paper develops a new risk assessment model for the passenger graded security check by introducing several new technologies to obtain the passengers’ real-time status information as well as historical data. We first propose to deploy a variety of 5G-IoT devices to monitor the passengers in real time, including high-definition cameras, millimeter-wave security detectors, etc. We then rely on machine learning to analyze the passenger risk level and integrate improved analytic hierarchy process (AHP) with group decision theory, namely GD-AHP. According to the risk level, the passengers can be classified into known, ordinary and dangerous targets. The differentiated handling of different targets could significantly save the time of security check and improve the passenger experience.

Bi-directional image-text retrieval and matching attract much attention recently. This cross-domain task demands a fine understanding of both modalities for learning a measure of different modality data. In this paper, we propose a novel position focused attention network to investigate the relation between the visual and the textual views. This work integrates the prior object position to enhance the visual-text joint-embedding learning. The image is first split into blocks, which are treated as the basic position cells, and the position of an image region is inferred. Then, we propose a position attention to model the relations between the image region and position cells. Finally, we generate a valuable position feature to further enhance the region expression and model a more reliable relationship between the visual image and the textual sentence. Experiments on the popular datasets Flickr30K and MS-COCO show the effectiveness of the proposed method. Besides the public datasets, we also conduct experiments on our collected practical large-scale news dataset (Tencent-News) to validate the practical application value of the proposed method. As far as we know, this is the first attempt to test the performance on the practical application. Our method achieves the competitive performance on all of these three datasets.

Perovskite transition metal oxides with ABO3 structure are considered as potential alternative non-precious metal electrocatalysts for designing highly active and durable electrocatalysis for the oxygen evolution reaction (OER). Herein, we successfully enable LaFeO3 coated on nickel foam (denoted LFO@NF) perovskite with impressive OER activity by systematically tailoring the Fe cation sites and the introduction of oxygen vacancies. The cationic site involves dual cation modulation with Cr and Mo, which creates lattice distortions inducing strong electronic interaction, while the anionic site entails reduction via a hydrogen-treatment process, creating oxygen vacancy sites to improve the electronic conductivity of the perovskite oxide. As a result, the optimized LFO-based catalyst, specifically hydrogenated LaFe0.75Cr0.15Mo0.10O3-coated on the nickel foam (denoted H-LFCMO@NF), requires the lowest overpotential of 263 mV at 10 mA cm−2, and has superior kinetics and excellent stability, which are superior to its counterparts. Theoretical analysis also confirmed that the tailoring of the LFO@NF perovskite leads to an increase in the exposure of active sites, optimization of the adsorption energy of reaction intermediates and enhanced electronic conductivity. This work may provide a promising concept to enhance the performance of LFO-based perovskite electrocatalysts for alkaline OER and beyond.

The critical behavior of single phase Y2Fe17 melt-spun ribbons with the Th2Fe17-type crystal structure has been studied around the transition temperature (TC). This alloy undergoes a second-order ferromagnetic (FM)–paramagnetic (PM) phase transition at TC = 301 K. Various techniques, such as the modified Arrott plot, Kouvel–Fisher method, and critical isotherm analysis, were used to determine the critical exponents that were found to be β = 0.226(3), γ = 1.296(2), and δ = 6.804(5). The universality class of the critical phenomenon in the Y2Fe17 ribbons can be explained with the help of the renormalization group theory approach, in which the magnetic properties show a feature changing from three (3D)- to two-dimensional (2D) Ising model. The first-principles calculations based on density functional theory qualitatively explain the experimental results, confirming the strong correlation between lattice atoms and critical behavior in magnetic intermetallic Y2Fe17.

Facilitated transport membranes, with a uniform distribution of facilitated transport carriers, are highly desirable to reduce the separation energy barrier. Nevertheless, the disordered and random assembly of membrane building materials/blocks makes it hard to obtain the controlled uniform distribution of carriers within membranes. Covalent organic frameworks (COFs), equipped with a regular structure and tailored functionality, provide a favorable platform for the uniform distribution of carriers. Herein, we report an ion-exchange strategy to achieve a uniform distribution of facilitated transport carriers within a cationic COF membrane for efficient carbon capture. With the assistance of a small amount of flexible graphene oxide (GO), the potential defects between the junctions of cationic COF nanosheets were eliminated, and ultrathin (20–60 nm), defect-free COF membranes were obtained. By synergistically intensifying the diffusion selective and facilitated transport mechanisms within membranes, the optimized COF membrane exhibits a CO2 permeance of 164.2 GPU with a CO2/CH4 selectivity of 27, both of which exceed those of pure COF membranes in most literature studies. Our findings may stimulate further research on functionalized COF membranes and other kinds of organic framework membranes with uniformly distributed carriers for molecule separation.

Bismuth vanadate (BiVO4) is one of the most fascinating building blocks for the design and assembly of highly efficient artificial photosynthesis devices for solar water splitting. Our recent report has shown that borate treated BiVO4 (B-BiVO4) results in an improved water oxidation performance. In this study, further improvement of both the photoelectrochemical (PEC) activity and stability of B-BiVO4 was successfully achieved by introducing NiFeV LDHs as an oxygen evolution catalyst and interfacial hole transporter. Benefiting from the synergistic effect of co-catalyst and borate pretreatment, the as-prepared NiFeV/B-BiVO4 exhibited a high photocurrent density of 4.6 mA cm−2 at 1.23 VRHE and an outstanding onset potential of ∼0.2 VRHE with good long-term stability. More importantly, NiFeV was found to play a pivotal role in the critically efficient suppression of charge combination on the BiVO4 surface and acceleration of charge transfer rather than a mere electrocatalyst for water oxidation.

Co-catalysts have been widely studied to improve photocatalytic water oxidation efficiency, and the precise control of their oxidation states and minimizing particle sizes can optimize the practical performance. In this work, ultrafine cobalt oxide (CoOx) co-catalysts with specific Co valence states have been successfully synthesized, which are anchored on a tantalum oxynitride (TaON) host photocatalyst via a photochemical metal–organic deposition method. Photoelectrochemical and photoluminescence analyses prove that the Co2+ dominant CoOx co-catalyst is favorable for charge separation and transportation because of its excellent hole-capturing properties, consequently enhancing the photocatalytic water oxidation performance. The resultant TaON with the Co2+ dominant CoOx co-catalyst exhibits an outstanding O2 production rate up to 6.10 ± 0.17 mmol h−1 g−1 and possesses an excellent apparent quantum efficiency of 21.2% at 420 nm, which are among the best values of water-oxidation photocatalysts.

Recently, hydrogel-based flexible sensors have attracted tremendous attention for use in wearable soft electronics. However, under sub-zero temperatures, common hydrogel-based flexible devices are always out of work due to their poor stability in freezing environments. To endow hydrogel-based sensors with long-term stability and anti-freezing ability as well as multi-functional abilities, we developed a polydopamine-reduced graphene oxide (PDA-rGO)/sodium alginate (SA)/polyacrylamide (PAM) composite organohydrogel with dual crosslinking networks. The excellent conductivity of the organohydrogel is due to the well-dispersed rGO endowed by mussel-inspired chemistry and ions such as Ca2+, which give the organohydrogel strain, pressure, and temperature sensing capabilities with a high gauge factor (2.09) within a broad strain range (0–250%), short response time (200 ms), and a wide temperature detection range (−20 °C to 60 °C), respectively. Moreover, the assembled sensors can also detect multiple human motions such as finger bending, facial micro-expression, and hand gesture recognition. Especially, owing to the synergistic effects of ion transportation, water–glycerol binary solvent, and the reduced graphene oxide in the composite hydrogel, the organohydrogel achieved an unprecedented thermal sensitivity of 97.60% °C−1 at sub-zero temperatures, which is the most sensitive stretchable thermistor so far reported. Therefore, this as-prepared functional organohydrogel paves the way for potential applications in human–machine interactions and personalized multi-signal monitoring in a broad temperature range.

High-quality epitaxial LaCoO3 (LCO) thin films have been deposited on SrTiO3 (STO) substrates with pulsed laser deposition (PLD). We find that the LCO films undergo a typical ferromagnetic–paramagnetic (FM–PM) phase transition at ∼80 K. To understand the nature of magnetic phase transition, various methods, including the modified Arrott plot and critical isotherm analysis, were used to determine the critical exponents, which are β = 0.754(1) with a Curie temperature TC = 79.8(8) K and γ = 1.52(2) with TC = 79.9(2) K. The reliability of these critical exponents was confirmed using the Widom scaling relation and the scaling hypothesis. Further analysis revealed that the spin coupling within the LCO films exhibits two-dimensional (2D) long-range magnetic interaction and the magnetic exchange distance decays as J(r) ∼ r−(3.46). Our critical behavior analysis may shed new light on the further understanding of the origin of FM and the relatively fixed TC in LCO thin films.