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The sandy area along the Great Wall in northern Shaanxi Province of China, is located in the transition zone between the Maowusu Desert and the loess hills and gullies region, with a vast territory and large per capita of cultivated agricultural land. However, the cultivated land quality is generally poor due to the local natural conditions. It is of practical significance to find ways to improve the quality of agricultural land and put forward targeted measures for its improvement. Through the analysis of farmland gradation results in the study area, we calculated an improvement potential index with a model to determine the primary limiting factors of agricultural land quality in the study area. The results indicate that both singe-factor and combined-factor limitations exist in the region. The single-factor limiting types include soil thickness, organic content, irrigation, salinization, etc., while the combined-factor limiting types include the combinations of the irrigation water source and irrigation firm probability, soil structure and organic matter, soil thickness and soil texture, and so on. Through the analysis of the potential index model results, we determined the main limiting factors in agricultural production, which vary spatially throughout the region, and suggested targeted measures to improve the cultivated land quality. These measures will then promote revitalization of sandy rural areas along the great wall in northern Shaanxi Province, China.

Electrocatalytic nitrogen reduction reaction (N2RR) in an aqueous solution suffers from unsatisfactory activity and selectivity for possible practical utilization. As the emerging catalyst for N2RR among various candidate non-metal catalysts, black phosphorus (BP) is promising but hasn’t been improved enough to solve those issues due to hugely exposed but inert surface P sites. In this work, a series of metals are chosen to adjust the coordination environment of inert surface P sites in bilayered BP (BPBL-M) by subsurface intercalation. The design principles of N2RR catalysts is investigated based on proton-coupled electron transfer theory by density functional theory (DFT). The BPBL-M with low-expanded interlayer-distances shows higher activity than bare BPBL and the first hydrogenation step for NNH* formation is potential determining step, where the activated N-N bond length correlates with N2RR activity. Meanwhile, the selectivity of N2RR on BPBL-M is regulated by intercalation as well. Considering the activity and selectivity altogether, the surface sites of BP yields higher activity and selectivity than the intrinsic BPBL after intercalation of Ni, Bi, Pd, and Ga. This model provides a new strategy from a theoretical perspective to activate the inert surface P sites to realize high intrinsic activity and high P site density for N2RR and broad new insight to design efficient 2D catalysts for N2RR.

The sol-gel process has been applied to cotton fabrics to cover the fibers with a silica-based film, which can improve their thermal oxidation and combustion behaviors. Silica sol, silane coupling agent 3-glycidoxypropyltrimethoxysilane (KH560) and flame retardant zinc borate (ZB) are used together to prepare SiO2-KH560-ZB hybrid sol, which is then finished on the surface of cotton fabric through impregnation and baking. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), limiting oxygen index analysis (LOI) and microscale combustion calorimetry (MCC) are used to characterize functional groups, thermal stability and flammability properties of finished fabrics. Surface morphology of sol modified cotton fabrics are analyzed by scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDX). Results show the sols are successfully converted into gel coatings onto cotton fabrics, and continuous smoldering phenomenon of resulted fabrics disappears. ΔLOI/Δm of SiO2-KH560-ZB coated cotton fabric reaches the highest of 0.37%/g, char residue rate is as high as 28.43% and the peak heat release rate (PHRR) is reduced by 26.9% (83.7 W/g). KH560 has a significant coupling effect on combining components in the sol system and increases compatibility between sols and cotton fabrics. ZB (cooling, separation, dilution and suppression), silica sol (physical barrier) and KH560 show excellent synergistic effects in enhancing overall flame retardancy.

In this paper, a nonlinear parameter-excited model of spinning pipes conveying fluid is proposed by considering the spinning speed and flow velocity are perturbed periodically, and the stability and nonlinear parametric vibrations of such system are studied analytically and numerically. With taking the viscoelastic material and geometrical nonlinearity due to extensible pipe axis into account, the differential equations governing two transverse vibrations of the pipe are derived by the Hamilton principle. The system stability is then analyzed via the multiple scales method, and the nonlinear responses and spatial vibration shapes are investigated using numerical simulation. The contributions of some significant parameters on the vibrations of the system are discussed in detail. It is revealed that not any other motion but combination parametric resonance with quasi-periodic motion mode can occur in the present system, and it is induced fully by the periodically perturbed fluid. A perturbed spinning motion cannot result in any parametric resonance, however it has an opposite effect on the parametric vibrations as compared to that with constant spinning speed. The flow velocity, nonlinearity and viscoelastic damping all have significant impacts on the present parametric vibrations. Moreover, the pipe performs different aperiodic whirling motions in the first two modes, and the perturbed spinning speed will lead to a gentler motion of the pipe as compared to the case of constant spinning speed.

Carbon fibre-reinforced silicon carbide composites (C/SiC) are a type of high-temperature structural ceramics that can be widely applied in aerospace, hypersonic aircraft, and military fields. However, the practical application of such materials in some complex high-temperature environments is still limited owing to drawbacks such as the bulging problem. In this study, the bulging of a C/SiC coating in a high-temperature wind tunnel is investigated. The surface data of specimens in the high-temperature arc wind tunnel were obtained using optical visualisation equipment, and the entire process of the formation of coating bulges, and their evolution and fusion is illustrated. Then, a fully coupled thermal fluid-solid simulation model is established, and the influence of defects on the internal heat transfer of materials is analysed. Further, the thermal fluid-solid coupling simulation technology is also used to analyse the bulging process of the coating to understand the mechanism of chemical reactions in defects between the coating and substrate. This work can serve as a guide for the screening and improvement of the material coating process.

The memristor is a foundational device for an artificial synapse, which is essential to realize next-generation neuromorphic computing. Herein, an optoelectronic memristor based on a two-dimensional (2D) transitional-metal trichalcogenide (TMTC) is designed and demonstrated. Owing to the excellent optical and electrical characteristics of titanium trisulfide (TiS3), the memristor exhibits stable bipolar resistance switching (RS) as a result of the controllable formation and rupturing of the conductive aluminum filaments. Multilevel storage is realized with light of multiple wavelengths between 400 and 808 nm, and the synaptic properties such as conduction modulation and spiking timing-dependent plasticity (STDP) are achieved. On the basis of the photonic potentiation and electrical habitual ability, Pavlovian-associative learning is successfully established on this TiS3-based artificial synapse. All these results reveal the large potential of 2D TMTCs in artificial neuromorphic chips.

The effect of Ti and Sb elements addition on the microstructures and corrosion resistance of hot-dip galvanized Zn-11Al-3Mg alloy was investigated by scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and Electrochemical workstation, respectively. Results showed that the grain size of the alloy was obviously refined with the addition of Ti and Sb elements, due to Al3Ti phase as the nucleation substrate resulted in the transformation of Al-rich phase from dendrite to petal-like. In addition, the pitting corrosion resistance of the alloy has been significantly enhanced.

An efficient and eco-friendly protocol for synthesizing difluoromethylated oxindoles through a visible-light induced one-pot tandem reaction of N-arylacrylamides, difluoroacetic acid and PhI(OAc)2 was developed. This reaction proceeded in the absence of any additive, base, metal-catalyst and external photosensitizer, using cheap and easily available CHF2CO2H as the difluoromethylation reagent and bulk biomass-derived 2-MeTHF as the sole solvent. 26 Examples of N-arylacrylamide substrates were investigated, and all of them successfully underwent difluoromethylation to deliver the target products in good to excellent yields.

The state-of-health (SOH) estimation of lithium-ion batteries (LIBs) is of great importance to the safety of systems. In this article, a novel ensemble learning method is proposed to accurately estimate the SOH of LIBs. A feature defined as the duration of the same charging voltage range (DSCVR) is extracted as the key health indicator for the LIB. The Pearson correlation analysis is performed to select four optimal indicators that are used as inputs of the prediction model. A random learning algorithm named extreme learning machine (ELM) is applied to extract the mapping knowledge relationship between the health indicators and the SOH due to its fast learning speed and efficient tuning mechanism. Moreover, an ensemble learning structure is proposed to reduce the prediction error of the single ELM models. A reliable decision-making rule is then designed to evaluate the credibility of the output of each single ELM model and remove the unreliable outputs, thereby significantly improving the accuracy and reliability of the estimation results. The testing results on two public data sets show that the proposed method can accurately estimate the SOH in 1 ms and is robust to the operating temperature and load profile. The average root-mean-square error (RMSE) is as low as 0.78%. The proposed method does not require any additional hardware or downtime of the system, which makes the method suitable for online practical applications. Nanyang Technological University The work of Bin Gou was supported in part by the National Natural Science Foundation of China (NSFC) under Grant 51907163. The work of Yan Xu was supported in part by the Nanyang Assistant Professorship from Nanyang Technological University.

This paper studies ordering and pricing issues of a retailer who faces a linear-sensitive demand. The definition of a reasonable retail price is put forward. After that, a deterministic model for trading off sales revenue and total cost is constructed, in which the retailer determines the optimal ordering schedule and the optimal retail price simultaneously for the sake of maximizing its total profit. It is shown that the acquired retail prices are all reasonable. During the process of derivation, both ordering time points and the optimal retail price are expressed as functions of ordering times. By solving a quadratic programming model with an undetermined parameter, we demonstrate that the optimal ordering time points of the retailer are equidistant time points on the given selling periods. Further, the sensitivity of each parameter is analyzed and some meaningful conclusions are drawn. Finally, the ordering times is obtained by analyzing the derivatives of the profit function.

The pyrolysis tar from Naomaohu coal was separated by distillation apparatus. Four components of heavy oil above 320°C were analyzed. The result showed the colloid content was 28.84% and the asphaltene content was 35.12%, and both were difficult to convert in hydrogenation. 13C-NMR results showed that the relative molar ratio of aromatic carbon in heavy oil was 71.16%, which indicated that aromatic compounds in heavy fraction were dominant. The heavy fraction was treated by suspension bed and fixed bed cracking. The asphaltene and colloid were almost completely converted. The yield of naphtha with boiling point below 180°C was 66.95%, and the diesel with boiling point higher than 180°C was 17.84%. Oxygen, nitrogen and sulfur contained in heteroatoms were almost completely removed. Catalytic reforming of naphtha was carried out. The results showed that the number of cycloalkanes decreased by 60.23%, and the number of aromatics increased by 65.8%, which indicated that the dehydrogenation and aromatization of cycloalkanes occurred mainly. While the number of n-alkanes decreased by 13.42%, which indicated that the isomerization and cyclization of n-alkanes occurred simultaneously. The catalytic reforming oil contained more benzene, toluene, xylene and ethylbenzene, and the contents were 11.97%, 23.15%, 21.43% and 3.48% respectively. In the direct conversion process of heavy oil from coal pyrolysis, the transmissibility of basic structural units of coal was significantly reflected.

Nowadays, controllable drug release is a vitally important strategy for cancer treatment and usually realized using implanting biocompatible devices. However, these devices need to be removed by another surgery after the function fails, which brings the risks of inflammation or potential death. In this article, a biodegradable flexible electronic device with controllable drug (paclitaxel) release was proposed for cancer treatment. The device is powered by an external alternating magnetic field to generate internal resistance heat and promote drug release loaded on the substrate. Moreover, the device temperature can even reach to 65 °C, which was sufficient for controllable drug release. This device also has similar mechanical properties to human tissues and can autonomously degrade due to the structure design of the circuit and degradable compositions. Finally, it is confirmed that the device has a good inhibitory effect on the proliferation of breast cancer cells (MCF-7) and could be completely degraded in vitro. Thus, its great biodegradability and conformity can relieve patients of second operation, and the device proposed in this paper provides a promising solution to complete conquest of cancer in situ.

Model composites consisting of SiC fiber embedded in β-Yb2Si2O7 matrix were processed by Spark Plasma Sintering method and the feasibility of tunable SiCf/Yb2Si2O7 interface in SiC-based CMCs were estimated. Weak and strengthened SiCf/Yb2Si2O7 interfaces were achieved by adjusting sintering temperatures. The indentation crack test and fiber push out experiments clearly demonstrated the different debonding mechanisms in the samples. Weak interfaces sintered at 1200 and 1250 °C exhibited crack deflection at interface in indentation test. Their low debond energy at the interface, which were comparable to those of PyC or BN, satisfied the well-recognized interfacial debond and crack deflection criteria for CMCs. The interface was strengthened by atomic bonding in model composite sintered at 1450 °C, leading to crack penetrating into SiC fiber and high debond energy. The strong interface may be promising in SiCf/SiC CMC to withstand higher combustion temperature, because Yb2Si2O7 will provide plastic deformation capacity, which would serve as weak interphase for crack deflection and energy dissipation. Therefore, it is possible to design the capability of SiCf/RE2Si2O7 interface for different requirements by adjusting interfacial strength or debond energy to reach optimal mechanical fuse mechanism in SiCf/SiC CMC.

Multiparameter integrated sensors are required for the next generation of flexible wearable electronics. However, mutual interference between detected signals is a technical bottleneck for a flexible tactile sensor to realize pressure-strain monitoring simultaneously and sensitively. Herein, a flexible dual-parameter pressure-strain sensor based on the three-dimensional (3D) tubular graphene sponge (TGS) and spider web-like stretchable electrodes is designed and fabricated. As the pressure-sensitive module, the unique 3D-TGS with an uninterrupted network of tubular graphene and high graphitic degree demonstrates great robust compressibility, supporting compression to ∼20% without shape collapse. The spider web-like stretchable electrodes as the strain-sensitive module are fabricated by a spray-embedded process based on the hierarchical multiscale hybrid nanocomposite of Ag nanowires (NWs) and carbon nanotubes (CNTs) with an optimal mass ratio. By comparing the output signals of spider web-like flexible electrodes, the magnitude and direction of the applied force can be effectively monitored simultaneously. Moreover, the potential applications of the flexible dual-parameter pressure-strain device in human-machine interaction are also explored, showing great promise in artificial intelligence and wearable systems.

An atomically dispersed structure is attractive for electrochemically converting carbon dioxide (CO2) to fuels and feedstock due to its unique properties and activity. Most single-atom electrocatalysts are reported to reduce CO2 to carbon monoxide (CO). Herein, we develop atomically dispersed indium (In) on a nitrogen-doped carbon skeleton (In-N-C) as an efficient catalyst to produce formic acid/formate in aqueous media, reaching a turnover frequency as high as 26771 h-1 at -0.99 V relative to a reversible hydrogen electrode (RHE). Electrochemical measurements show that trace amounts of In loaded on the carbon matrix significantly improve the electrocatalytic behavior for the CO2 reduction reaction, outperforming conventional metallic In catalysts. Further experiments and density functional theory (DFT) calculations reveal that the formation of intermediate *OCHO on isolated In sites plays a pivotal role in the efficiency of the CO2-to-formate process, which has a lower energy barrier than that on metallic In.

In recent years, discriminative correlation filter (DCF) based algorithms have significantly advanced the state of the art in visual object tracking. The key to the success of DCF is an efficient discriminative regression model trained with powerful multi-cue features, including both hand-crafted and deep neural network features. However, the tracking performance is hindered by their inability to respond adequately to abrupt target appearance variations. This issue is posed by the limited representation capability of fixed image features. In this work, we set out to rectify this shortcoming by proposing a complementary representation of a visual content. Specifically, we propose the use of a collaborative representation between successive frames to extract the dynamic appearance information from a target with rapid appearance changes, which results in suppressing the undesirable impact of the background. The resulting collaborative representation coefficients are combined with the original feature maps using a spatially regularised DCF framework for performance boosting. The experimental results on several benchmarking datasets demonstrate the effectiveness and robustness of the proposed method, as compared with a number of state-of-the-art tracking algorithms.

Mesoporous single crystals have attracted considerable attention owing to their wide applications in (photo)catalysis, photovoltaics, and numerous other electrical energy conversion and storage technologies. Here, by using low-valent Ti3+ precursors, we have successfully synthesized well-defined mesoporous single-crystal strontium titanate (MSC SrTiO3) without a template via a facile hydrothermal method. The BET surface area and average pore diameter of MSC SrTiO3 are 18.6 m2 g−1 and 22 nm, respectively. Moreover, the as-synthesized MSC SrTiO3 features abundant oxygen vacancies. By using time-dependent structural and morphological characterizations, a hypothetical crystal growth mechanism was proposed.

The novel human infectious coronaviruses (CoVs) responsible for severe respiratory syndromes have raised concerns owing to the global public health emergencies they have caused repeatedly over the past two decades. However, the ongoing coronavirus disease 2019 (COVID-19) pandemic induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has received unprecedented attention internationally. Monitoring pathogenic CoVs in environmental compartments has been proposed as a promising strategy in preventing the environmental spread and tracing of infectious diseases, but a lack of reliable and efficient detection techniques is still a significant challenge. Moreover, the lack of information regarding the monitoring methodology may pose a barrier to primary researchers. Here, we provide a systematic introduction focused on the detection of CoVs in various environmental matrices, comprehensively involving methods and techniques of sampling, pretreatment, and analysis. Furthermore, the review addresses the challenges and potential improvements in virus detection techniques for environmental surveillance.

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.

A reverse-blocking AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (RB-MISHEMT) is proposed and fabricated. Compared with the conventional MISHEMT with ohmic drain, the proposed device features a hybrid Schottky-ohmic drain with a low work function Tungsten (W), based on which the state-of-the-art ultralow turn-on voltage ( ${V} _{\mathrm{ on}}$ ) of 0.25 V could be realized without degradation in on-state characteristics. In addition, the fabricated RB-MISHEMT exhibits the excellent reverse blocking voltage of −1332 V (at ${V} _{\mathrm{ GS}}= 0$ V) and forward blocking voltage of 1315 V (at ${V} _{\mathrm{ GS}} = -15$ V) with a specific on-resistance ( ${R} _{\mathrm{ on,sp}}$ ) of 3.5 $\text{m}\Omega $ cm2, leading in the highest power figure-of-merit (FOM) of > 494 MW/cm2. The good thermal stability could also be observed in fabricated RB-MISHEMT. The corresponding operation mechanism of RB-MISHEMT are also revealed by Silvaco ATLAS simulations. These results demonstrate the great potential in power electronics applications.

Transfer printing has emerged as a deterministic assembly technique for moving thin-film semiconductors into desired layouts by using rubber stamps; however, replicating transfer printing for different semiconductors fails to achieve high efficiency, hindering the fast development of flexible hybrid electronics. In this work, a novel transfer printing technique using droplet stamps is developed based on Laplace pressure and surface tension. The working principle is explained by liquid bridge analysis and demonstrated by a 100% yield of transfer printing a batch of thin-film semiconductors with different materials, sizes, and shapes. Besides, the droplet stamps are used in fabricating epidermal hybrid optoelectronics for accurate blood pressure monitoring to verify their high working efficiency. Thus, taking advantage of eliminating Poisson effects and solving the incompatibility with conventional fabrication technologies, this technique will play an enabling role in hybrid integration and high-fidelity fabrication.

Analyzing scattered wave to recognize object is of fundamental significance in wave physics. Recently-emerged deep learning technique achieved great success in interpreting wave field such as in ultrasound non-destructive testing and disease diagnosis, but conventionally need time-consuming computer postprocessing or bulky-sized diffractive elements. Here we theoretically propose and experimentally demonstrate a purely-passive and small-footprint meta-neural-network for real-time recognizing complicated objects by analyzing acoustic scattering. We prove meta-neural-network mimics a standard neural network despite its compactness, thanks to unique capability of its metamaterial unit-cells (dubbed meta-neurons) to produce deep-subwavelength phase shift as training parameters. The resulting device exhibits the “intelligence” to perform desired tasks with potential to overcome the current limitations, showcased by two distinctive examples of handwritten digit recognition and discerning misaligned orbital-angular-momentum vortices. Our mechanism opens the route to new metamaterial-based deep-learning paradigms and enable conceptual devices automatically analyzing signals, with far-reaching implications for acoustics and related fields., The authors present a passive meta-neural-network for real-time recognition of objects by analysis of acoustic scattering. It consists of unit cells termed meta-neurons, mimicking an analogous neural network for classical waves, and is shown to recognise handwritten digits and misaligned orbital-angular-momentum vortices.

This paper proposes a flexible data-driven method for online estimating the State of Health (SOH) of Li-ion batteries in both charging and discharging modes. Based on comprehensive battery aging data analytics, a novel health indicator called voltage variance during equal time interval (VVETI) is extracted. The VVETI can be extracted during either charging or discharging mode. For online applications, the indicator is derived from a small segment of charge/discharging curves. Unlike existing methods, the indicator can be extracted in various voltage ranges which is highly flexible for application. Then, a hierarchical ensemble model of extreme learning machine (ELM) is proposed as the machine learning engine for accurate SOH estimation. The proposed method is tested on three open datasets and reports a very high accuracy (average RMSE below 0.5% under appropriate voltage ranges).

Slag flow behaviour is critically important in the lower zone of the ironmaking blast furnace, and is closely related to the selection of charged raw materials, coke bed permeability, process stability and hot metal quality. To better understand the effect of slag properties on flow behaviour in the coke bed, a numerical approach was applied to characterize the slag flow through funnel analogues. These analogues were used to represent molten slag flow through the inter-particle voids of a coke packed bed. A critical funnel neck size, through which no slag flowed was experimentally established and confirmed by numerical modelling. The influence of slag wettability on the occurrence of blockage was also determined via numerical modelling. An increase in either contact angle or surface tension can make the occurrence of blockage easier. For a constant neck size, the relationship between surface tension and contact angle is non-linear. The status of the remaining slag in the funnel corresponding to different slag wettabilities was differentiated in terms of the blockage in the upper part and hanging in the lower part of the funnel. Modelling was also undertaken of slag flow through the inter-particle void between spherical particles to evaluate empirical correlations for predicting the remaining slag in the packed bed. These results show that the numerical approach is very useful in providing some level of guidance to help understand and predict the slag flow behaviour in the blast furnace ironmaking process.

Size uniformity of single tracks has a significant influence on the quality of parts in metal additive manufacturing. Herein, the 7075 aluminum alloy single tracks were fabricated by self-developed liquid metal flow rapid cooling additive manufacturing equipment. The forming process of single tracks was observed by a high-speed camera. The effects of process parameters on the size uniformity of the single tracks were analyzed. The influence mechanism of size uniformity of the single tracks was revealed. The results show that the size uniformity of 7075 aluminum alloy single tracks increases with increasing discharge pressure, melt superheat and deposition distance, or decreasing nozzle travelling speed. The variation of the inclination angle of the solid-liquid interface and the distance between solid-liquid interface and liquid flow under different process parameters results in the variety of size uniformity of the single tracks. The work would provide a new technical idea and theoretical basis for investigating the size uniformity of single tracks prepared by additive manufacturing.

Lithium-ion (Li-ion) batteries have been widely applied in industrial applications. It is desired to predict the health state of batteries to achieve optimal operation and health management. However, accuracy is the biggest bottleneck for battery health prediction. In this paper, a new hybrid ensemble data-driven method is proposed to accurately predict the state-of-health (SOH) and remaining-useful-life (RUL) of Li-ion batteries. A health indicator is selected as feature inputs to predict the degradation trend of battery, after the Pearson correlation analysis. Two random learning algorithms are integrated to extract the inherent relationship between the extracted health indicator and practical SOH due to their good learning performance. Based on the estimated SOH, the nonlinear autoregressive (NAR) structure is designed to reduce the RUL prediction error of each learning model since the NAR structure makes good use of historical and current information. Finally, in order to quantitatively evaluate the prediction interval of the RUL, a Bootstrap-based uncertainty management method is designed. Test results on two publicly available datasets show that the proposed hybrid data-driven method can accurately predict the SOH and RUL of batteries. The proposed method does not require any other additional hardware or system downtime, which makes it suitable for online practical applications, such as energy storage systems and electric vehicles.

Energy storage system (ESS) management benefits the operation of all-electric ships (AESs) since its ability to balance the generation and demand. However, current works rarely consider the influence of navigation uncertainties, i.e., uncertain water waves and winds, and fail to address two characteristics of shipboard ESS, i.e., redundant capacity and distributed locations. In this paper, a two-stage robust optimal shipboard microgrid operation method is proposed to mitigate the pre-voyage and intra-voyage navigation uncertainties. The first stage is to regulate the onboard generation and voyage variables for addressing the worst pre-voyage navigation uncertainties and the second stage is an on-line recourse action which acts on intra-voyage uncertainty realization. To address the characteristics of shipboard ESS, the onboard batteries are separated into two groups and a multi-battery management strategy is proposed for the battery lifetime extension. An AES with 4 DGs and 4 batteries is used in the case studies. The simulation results show that the proposed method can well adapt to the navigation uncertainties and the multi-battery management can extend the battery lifetime by iteratively using different battery groups.

Structural ceramics such as C/SiC (carbon fiber reinforced silicon carbide) are of great importance for high temperature applications, where thermal ablation could occur and impair the structural integrity. Here we adopt in situ and real time optical visualization technique and numerical simulation to study the thermal ablation mechanisms of C/SiC subjected to oxyacetylene flame. The in situ optical setup captures the real time surface evolution at temperatures up to 1800℃, demonstrating clearly the formation of surface gas bubble, the flowing and merging process of liquid SiO2, which are later well reproduced and explained by the numerical simulation. Four different surface ablation regions on the sample subjected to thermal ablation have been identified by the captured images and flow field streamlines, which reveal the distribution and flow mechanism of SiO2 droplets on the C/SiC surface.

Spinel lithium manganese oxide ion-sieves have been considered the most promising adsorbents to extract Li+ from brines and sea water. Here, we report a lithium ion-sieve which was successfully loaded onto tubular α-Al2O3 ceramic substrates by dipping crystallization and post-calcination method. The lithium manganese oxide Li4Mn5O12 was first synthesized onto tubular α-Al2O3 ceramic substrates as the ion-sieve precursor (i.e. L-AA), and the corresponding lithium ion-sieve (i.e. H-AA) was obtained after acid pickling. The chemical and morphological properties of the ion-sieve were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Both L-AA and H-AA showed characteristic peaks of α-Al2O3 and cubic phase Li4Mn5O12, and the peaks representing cubic phase could still exist after pickling. The lithium manganese oxide Li4Mn5O12 could be uniformly loaded not only on the surface of α-Al2O3 substrates but also inside the pores. Moreover, we found that the equilibrium adsorption capacity of H-AA was 22.9 mg·g−1. After 12 h adsorption, the adsorption balance was reached. After 5 cycles of adsorption, the adsorption capacity of H-AA was 60.88% of the initial adsorption capacity. The process of H-AA adsorption for Li+ correlated with pseudo-second order kinetic model and Langmuir model. Adsorption thermodynamic parameters regarding enthalpy (∆ H), Gibbs free energy (∆ G) and entropy (∆ S) were calculated. For the dynamic adsorption–desorption process of H-AA, the H-AA exhibited excellent adsorption performance to Li+ with the Li+ dynamic adsorption capacity of 9.74 mg·g−1 and the Mn2+ dissolution loss rate of 0.99%. After 3 dynamic adsorption–desorption cycles, 80% of the initial dynamic adsorption capacity was still kept.

Interface is the Achilles' heel in flexible electronics, where slipping, delamination, or cracking resulting from the intrinsic mechanical property mismatch of different materials might fail the device or cause degradation. Robust connections with strong interfacial strength and low interfacial impedance are highly desired in all kinds of flexible devices, especially when they require stretchability. Here, a new strategy of employing homogeneity is proposed to facilely achieve robust connection without introducing a third-party interlayer. The key to this strategy is implementing different functions in the same component materials, and in this work, this strategy is demonstrated by exploring the uniformity of carbon nanotube (CNT) in thermoplastic polyurethane (TPU) elastomer. Tuning the uniformity of CNT in TPU elastomer, two kinds of CNT-TPU composites (CTCs) are fabricated. They present contrasting properties of conductivity (281 folds), Young's modulus (7.1 folds), and strain sensitivity (15.7 folds) with the same weight fraction of CNT (15 wt %), and thus they can respectively act as strain sensor and interconnector in all-CNT-based stretchable strain monitoring electronics. The interlocking effect caused by spontaneous entanglement of surface polymer chains and the reconstruction of percolation network at the interface during drying confer the connection with robustness. The practical value of this strategy has been exemplified by the fabrication of a robust epidermis device via additive manufacturing. This epidermis device is patterned in a fractal motif for conformal contact and can sensitively monitor body motions and radial artery pulse.

本工作提出了一种插层剂辅助的等离子体液相技术用于高 效地剥离高质量少层二维材料. 采用氯化锂为插层剂可快速剥离 石墨纸, 形成具有小D峰/G峰比(0.02)以及大碳氧比(31.5)的石墨烯 产物. 并且, 这种方法可以拓展至高质量少层2H相二硫化钼的制 备. 和传统的插层剂辅助电化学方法相比, 等离子体诱导产生的大 量活性粒子以及快速的电子转移, 使得插层剂辅助的等离子体液 相技术剥离的产物缺陷少且不会引入额外的基团. 这种可控的快 速剥离方法在制备其他各种类型的高质量二维材料方面都具有巨 大潜力.

The influence of brazing temperature and brazing time on the microstructure and shear strength of γ-TiAl/GH536 joints brazed with Ti−Zr−Cu−Ni−Fe−Co−Mo filler was investigated using SEM, EDS, XRD and universal testing machine. Results show that all the brazed joints mainly consist of four reaction layers regardless of the brazing temperature and brazing time. The thickness of the brazed seam and the average shear strength of the joint increase firstly and then decrease with brazing temperature in the range of 1090−1170 °C and brazing time varying from 0 to 20 min. The maximum shear strength of 262 MPa is obtained at 1150 °C for 10 min. The brittle Al3NiTi2 and TiNi3 intermetallics are the main controlling factors for the crack generation and deterioration of joint strength. The fracture surface is characterized as typical cleavage fracture and it mainly consists of massive brittle Al3NiTi2 intermetallics.

In this letter, the stacked dual-slotted substrate integrated cavities (SICs) are proposed to achieve a filtering antenna. The dual-slotted SIC shows dual-mode behavior (quasi-dual-slot mode and quasi-cavity mode), which can achieve multiorder response with fewer SICs. Furthermore, the antenna exists at two frequencies at which the electric field has opposite horizontal component ( $E_{x}$ ) near each slot. Thus, two radiation nulls can be obtained to enhance the frequency selectivity. The frequencies of the radiation nulls and the dual modes can both be controlled to some extent by the distance between the slots. For demonstration, a prototype at 9.65 GHz is designed with the fractional bandwidth of 9.1%, the gain of 7.2 dBi, and the frequency selectivity of 0.70.

In this paper, a new type of controller based on the combined integrating systems is proposed, which is called a combined integrating controller. The controller’s current output is determined only by the current input and the average value of the controller’s previous output. The innovation is to introduce a time-delay positive feedback in the controller. The memory characteristics of the time-delay term keep accumulating error information and repeatedly learning so that the system can stably track and restrain any input signal without error. Simultaneously, the combined integrating controller is applied to conventional process systems based on dynamic optimization estimation in the case study to show absolute superiority over the nonpredictive control method (such as the classical PID control method).

The diversity of hemicellulose oligomers enables many potential applications, but controlling yield and oligomer molar mass is challenging. Oligomer production by hydrolysis of softwoods was invest...

This paper studies the robust operation of a novel hybrid AC/DC multi-energy ship (MES) microgrid with flexible thermal loads and voyage. Apart from the diesel generators and battery storage, the photovoltaic system, combined cooling heat and power (CCHP) unit, thermal storage and power-to-thermal conversion unit are also included. Then, to guarantee a safe and reliable voyage, the diverse uncertainties from renewable energies, onboard power loads and outdoor temperature are addressed by a robust coordination method. This method coordinates all the onboard units in different timescales by the two-stage robust optimization (RO) approach. In this regard, the ship operating cost is minimized under the worst case of uncertainties, at the same time, all the operational constraints are fully satisfied. By the constraint linearization process, the robust coordination model is formulated as a mixed-integer linear programming (MILP) problem and solved by the efficient Cplex solver. Finally, the effectiveness of the proposed method is verified by the case study and comparisons with the existing ship operation benchmarks. The simulation results indicate that our method could reduce the ship operating cost and immune against the diverse uncertainties.

Salesforce compensation and pricing decisions have invoked the interest of several academicians and practitioners for a long period of time. However, dilemma of whether the pricing decisions should be made by the firm or delegated to the sales agent, especially the overconfident agent, is still unexplored. This study tries to investigate the problems associated with this dilemma by conducting a thorough study of the scenario, it studies a supply chain that the rational manufacturer hiring an overconfident sales agent to sell its products, the agent might overestimate the demand, or underestimate the variability of the demand. These behaviors are characterized as ability-based and precision-based overconfidence respectively. The models are designed for centralized pricing and delegated pricing settings, and the sensitivity analysis are conducted. Moreover, comparative studies have also been conducted to highlight the impacts of the two types of overconfidence on the compensation decisions under different pricing strategies. It was found out that, the manufacturer favors centralized pricing, while the sales agent prefers delegated pricing. The final decisions of both sides deviate considerably from the rational scenario, overconfidence prompts the agent to exert more efforts, which ultimately enhances manufacturer’s profits that the manufacturer should hire a more overconfident agent, while not guaranteeing a higher commission rate. Overconfidence leads to the decline of the agent’s actual utility, and the loss amount increases with the overconfidence level. The influences of the both types of overconfidence are substitutable. Managerial insights are also provided for various scenarios and propositions along with numerical illustration of the finding.

Diamond like carbon (DLC) films with different C–C sp2/sp3 ratios were prepared by tuning the N2 flow rate in a filtered cathodic vacuum arc (FCVA) system. The increase of N2 flow rate facilitated the increase of C–C sp2/sp3 ratio (1.09–2.66), the growth of particle size (0.78–1.58 nm) and the improvement of surface roughness. The SBF immersion results, as well as WCAs (77.57°~71.71°), hemolysis rate (0.14–1.00%) and cytotoxicity level (0) demonstrated that the as-fabricated DLC film was promising for biomedical application. As a result of surface charge effect, the apatite layers formed in the SBF increased with the increase of C–C sp2/sp3 ratio until 1.74 and then showed a tiny decrease during 1.74–2.66. A raise of hemolysis and cytotoxicity was observed when sp2/sp3 ratio was increased. Moreover, a decrease of friction coefficient of Si surface induced by increasing sp2/sp3 ratio was respectively evidenced in ambient air and SBF lubrication environments., Graphical abstract Image 1, Highlights • The sp2/sp3 ratio of DLC film is tuned by varying the N2 flow rate. • The apatite formation ability increases with the increase of sp2/sp3 ratio until 1.74. • DLC films show good antihemolysis and low cytotoxicity level.

Nano coir cellulose whiskersare materials abstracted from mesocarp of coconut shell which was modified by using KH570 as a coupling agent and modified nano coir cellulose whiskers need to be dispersed in chitosan/polyvinyl alcohol (CS/PVA) mixture solution. Because of regular structure and high crystallinity, nano coir cellulose whiskers could be applied in medical materials.In this paper, the results obtained with solution casting method by characterizing and analyzing structure, thermal properties, crystallization behavior and morphology of nano coir cellulose whiskers enhanced CS/PVA composite filmby FTIR, DSC, TG, XRD and SEM test. Different content of modified nano coir whiskers and CS/PVA composite film were preparedand themechanical properties of the composite film were also conducted. The results show that the tensile strength and Young's modulus of the CS/PVA composite film with modified nano coir whiskers are significantly improved, and Elongation break increases at first and then decreases, which indicates nano coir cellulose whiskers are good materials for medical purpose.

Cherenkov radiation (CR) is the electromagnetic shockwaves generated by the uniform motion of charged particles at a velocity exceeding the phase velocity of light in a given medium. In the Reststrahlen bands of hexagonal boron nitride (hBN), hyperbolic phonon polaritons (HPPs) are generated owing to the coupling between mid-infrared electromagnetic waves and strong anisotropic lattice vibrations. This study theoretically and numerically investigates the generation of volume CR based on HPPs in hBN with super-large wavevectors. Results reveal that CR can be generated using free electrons with an extremely low kinetic energy of 1 eV—two orders of magnitude lower than that reported in extant studies. The findings of this investigation provide new insights into significantly reducing the electron energy required for CR generation and potentially open new research avenues in the fields of CR and HPP.

Precise size control and general synthesis of ultrafine noble metal-based catalysts are very important in electrochemical energy conversion technologies. Herein, we develop the ultrafine MCu (M = P...

Offloading has been widely adopted as an effective technique to overcome the processing and computation limitation in mobile networks. In this paper, a utility maximization model of mobile ad hoc environment with some malicious resource providers (RPs) is built. The price incentive mechanism obtained by solving the model can effectively promote RPs to share their idle resources to resource buyer (RB). To identify the malicious RPs, the mechanism of identification and processing the inaccurate data is designed and completed by RB. Combined with this mechanism, we propose a distributed optimization algorithm based on modified alternating direction method of multipliers (ADMM) algorithm to realize the maximum utility of the overall system. Finally, through comparative analysis, the simulation results verify the feasibility of the proposed distributed optimization algorithm and the necessity of identifying malicious RPs.

A three-dimensional finite element model of stratum-cement ring-casing-cement plug was established for the failure analysis of the cement plug seal in the abandoned oil and gas wells. The mechanical parameters, length, bottom fluid pressure and casing swaging length of the cement plug under non-uniform ground stress conditions were analyzed. The results showed that when the bottom of the cement plug was subjected to fluid pressure, the stress at the interface between the cement plug and the casing increased, and thereby the cement plug at the bottom and the cementation of the casing failed, resulting in a the decrease in the sealing performance of the cement plug, which may be sealed under fluid corrosion. As the modulus of elasticity and the radius of the cement plug increased, the cement plug stress and the cement failure length increased. As the cement plug length increased, the cement plug stress and the cement failure length decreased, while Poisson's ratio for the cement plug stress and the cement failure length increased. The increase of the bottom fluid pressure could increase the cement plug stress and the cementation failure length. In the abandoned well, where the casing was forged and then grinded after the casing was forged, the length of the casing milling increased, the plug stress of cement reduced. These findings can provide insightful potentials for the parameters of cement plugs when the cement plugs are closed in the offshore oil and gas wells.

Flexible pressure sensing is required for the excellent sensing performance and dexterous manipulation of the measured objects in their potential applications. Particularly, the ability to measure and discriminate the direction of force, contact surface, and contact location in real time is crucial for robotics with tactile feedback. Herein, a three-dimensional elastic porous carbon nanotube (CNT) sponge is synthesized by chemical vapor deposition, which is successfully applied in the piezoresistive sensor. In situ scanning electron microscopy study intuitively illustrates the characteristics that the microfibers of the CNT sponge distort and contact with each other under an external force. As a result, new conductive paths are created at the contact points between the CNT microfibers, which provides a basic sensing principle for a piezoresistive sensor. The CNT sponge-based sensor has an ultrahigh sensitivity in a wide pressure range (0-4 kPa for 4015.8 kPa-1), a rapid response time of 120 ms, and excellent durability over 5000 cycles. Moreover, a finlike flexible double-sided electronic skin (e-skin) is fabricated by a simple method to achieve force direction detection, which has potential applications in intelligent wearable devices and human-machine interaction.

Through pyrolysis under a supercritical water (SCW) environment, the demetallization of Tsingtao vacuum residuum (VR) and Tahe atmospheric residuum (AR) with a total vanadium and nickel content above 300 ppm was studied. By introducing SCW, pyrolysis of heavy oil can be carried out in an emulsion structure in which heavy fractions rich in metals are concentrated in oil droplets. A metal removal rate higher than 90 % could be obtained in 2 h, which is faster than the pyrolysis under the nitrogen environment. Although two heavy oils have similar apparent properties, Tsingtao VR is characterized by the metal enrichment in the heaviest asphaltenes and the higher condensation activity of asphaltenes. Because of the preferential condensation of heavy fractions rich in metals, the liquid product yield of Tsingtao VR could be 15 wt% higher than that of Tahe AR at the metal removal rate of 70 to 90%.

This manuscript presents a novel structure of combined integration in the process industry and proposes an efficient method for identifying its parameters. Combined integrating processes are delay-time processes that widely exist in the industry. Conventional identification methods have a low-identification accuracy, a large vibration amplitude of the identification curve, and a poor effect for this kind of process. In this paper, a new variable forgetting factor recursive least squares method was adopted to ameliorate this problem. The method could quickly track the mutation of the ideal parameters of the process and accurately identify which of the parameters has high precision, small oscillation, and a smooth curve. The simulation results indicate that the proposed method is a significant improvement compared to the ordinary recursive least squares method and the recursive least squares with a fixed forgetting factor method, and a concise program can be verified. The experimental simulation based on the actual cut tobacco rebaking industrial process shows that the proposed method has improved identification precision and the best following effect.

Branched polyethylene (B-PE) elastomer was investigated for its potential medical application as a tarsus construct. The in vitro results showed that the B-PE and processed B-PE films or scaffolds did not exhibit noticeable cytotoxicity to the NIH3T3 fibroblasts and human vascular endothelial cells (ECs). The B-PE scaffolds with a pore size of 280–480 µm were prepared by using a gelatin porogen-leaching method. The porous scaffolds implanted subcutaneously in rats exhibited mild inflammatory response, collagen deposition and fast fibrovascularization, suggesting their good biocompatibility. Quantitative real-time PCR analysis showed low expression of pro-inflammatory genes and up-regulated expressions of collagen deposition and vascularization-related genes, validating the results of historical evaluation in a molecular level. The B-PE scaffolds and Medpor controls were transplanted in rabbits with eyelid defects. The B-PE scaffolds exhibited a similar elastic modulus and provided desirable repair effects with mild fibrous capsulation, less eyelid deformities, and were well integrated with the fibrovascular tissue compared with the Medpor controls.

MXenes are a new type of two-dimensional material, and they have attracted extensive attention because of their outstanding conductivity and rich surface functional groups that make surface enginee...

According to the statistics of the World Health Organization, an estimated 17.9 million people die from cardiovascular diseases each year, representing 31% of all global deaths. Continuous non-invasive arterial pressure (CNAP) is essential for the management of cardiovascular diseases. However, it is difficult to achieve long-term CNAP monitoring with the daily use of current devices due to irritation of the skin as well as the lack of motion artifacts suppression. Here, we report a high-performance skin-like optoelectronic system integrated with ultra-thin flexible circuits to monitor CNAP. We introduce a theoretical model via the virtual work principle for predicting the precise blood pressure and suppressing motion artifacts, and propose optical difference in the frequency domain for stable optical measurements in terms of skin-like devices. We compare the results with the blood pressure acquired by invasive (intra-arterial) blood pressure monitoring for >1500 min in total on 44 subjects in an intensive care unit. The maximum absolute errors of diastolic and systolic blood pressure were ±7/±10 mm Hg, respectively, in immobilized, and ±10/±14 mm Hg, respectively, in walking scenarios. These strategies provide advanced blood pressure monitoring techniques, which would directly address an unmet clinical need or daily use for a highly vulnerable population., We demonstrate skin-like optoelectronic systems that can monitor continuous non-invasive arterial pressure, which would directly address a clinical need or daily use for the population.

Development of efficient catalysts for ammonia production under ambient conditions is a challenge. In this work, edge-rich black phosphorus nanoflakes (eBP NFs) are synthesized for highly efficient photocatalytic nitrogen fixation. The eBP NFs synthesized by a chemical etching exfoliation method have a uniform size and about 90 nm wide and the flake-like structure is enshrouded with crystal-domain edges. Without using any cocatalysts, the eBP NFs catalyze nitrogen fixation at a rate of 2.37 mmol·h-1·g-1 under visible-light irradiation. The photocatalytic process is analyzed by photoelectrochemical and transient absorption measurements, which disclose electron transfer from eBP NFs to N2 for subsequent hydrogenation. Besides the facile and scalable synthesis method, eBP NFs with a high photocatalytic nitrogen fixation efficiency have great potential in ammonia production.