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Considering the strong nonlinearity of Unmanned Aerial Vehicles (UAVs) resulting from high Angle of Attack (AoA) and fast maneuvering, we present a multi-model predictive control strategy for UAV maneuvering, which has a small amount of online calculation. Firstly, we divide the maneuver envelope of UAV into several sub-regions on the basis of the gap metric theory. A novel algorithm is then developed to determine the ploytopic model for each sub-region. According to this, a Robust Model Predictive Control based on the Idea of Comprehensive optimization (ICE-RMPC) is proposed. The control law is designed offline and optimized online to reduce the computational expense. Then, the ICE-RMPC method is applied to design the controllers of sub-regions. In addition, to guarantee the stability of whole closed-loop system, a multi-model switching control strategy based on guardian maps is put forward. Finally, the tracking performance of proposed control strategy is demonstrated by an illustrative example.

Ni–Fe–Sn electrocatalyst supported on nickel foam (Ni–Fe–Sn/NF) with high efficiency of hydrogen evolution reaction (HER) has been successfully fabricated through one-step potentiostatic electrodeposition route. The optimized Ni–Fe–Sn/NF displayed an extremely low overpotential of, respectively, 144 and 180 mV at 50 and 100 mA cm−2 for HER in alkaline condition. Moreover, it could retain its superior stability for at least 12 h. The remarkable electrocatalytic activity of our electrocatalyst is ascribed to the high conductivity originated from synergistic effects between Ni, Fe, and Sn during HER process.

The object-based video forgery detection aims to expose tampered regions from video sequences without any codec information. However, existing methods mainly focus on manually selected features and models for a specific task, either splicing or copy-move, while the general representation ability of deep learning models and the correlation of different forensic features have not been fully explored. In this letter, we propose a dual-stream framework to jointly discover and integrate effective features for object-based video forgery detection. First, two different types of branches are employed to extract discriminative features. Then, after the dual-stream feature fusion, a Conditional Random Field (CRF) layer is utilized to further refine segmentation results. Finally, we consider temporal consistency by incorporating the video tracking strategy. Depth information is adopted to refine the localization results. Extensive experiments on four datasets show that the proposed method achieves competitive performance against the state-of-the-art methods.

Ultrasmall nitrogen-doped carbon-coated CoSe2/ZnSe nanospheres (CoSe2/ZnSe@C nanospheres) are fabricated by direct selenization of a delicately designed Co1.6Zn0.4-(benzimidazole)4 metal–organic framework (MOF) nanosheet precursor and used as the anode materials in sodium-ion batteries (SIBs). The fabricated CoSe2/ZnSe@C nanospheres deliver a remarkable rate performance (395 mAh g−1 at 0.1 A g−1 and 341 mAh g−1 at 5.0 A g−1) and excellent long-term durability (346 mAh g−1 after 2500 cycle at 2.0 A g−1). The superior Na storage performance of the fabricated CoSe2/ZnSe@C nanospheres could be mainly attributed to their ultrasmall particle sizes and the phase boundaries between CoSe2 and ZnSe, which improve the kinetics of the electrode, relieve the volume change during the charge/discharge process, and provide extra Na+ storage sites. This work opens up possibilities to fabricate metal selenide–based hybrid materials with desired nanostructures and compositions from rationally designed multimetal MOF precursors for high-performance anode materials in SIBs.

Application of nitrogen-doped carbon for electroreduction of CO2 to CO receives increasing attentions, and improving the CO selectivity of carbon-based materials is prominent. Here we introduce a halogen-assisted calcination strategy for constructing two-dimensional (2D) nitrogen-doped carbon from ZIF-8 precursor. Benefitting from the abundant graphitic-N (G-N) and the enlargement of electrochemical surface area (ECSA), 2D nitrogen-doped carbon presents excellent catalytic activity with the high faradaic efficiency (FE) of CO reaching 99.5% and current density of −2.6 mA cm−2 at a low potential of −0.5 V (vs. RHE) in H-type cell, with the long-term stability up to more than 20 h. A positive correlation between FECO and the ratio of G-N (the ratio of graphitic-N content to total N content.) is revealed. The halogen-assisted calcination can effectively increase the G-N ratio and enlarge ECSA, thereby increasing FECO, which is a promising strategy for improving CO selectivity of carbonaceous materials.

The visual inspection algorithms are the core of automatic optical inspection system on surface mounting machines. This article is concerned with the development of precise positioning algorithms for circular mark points and transistor (TR) components on surface mounting devices. To handle nonuniform illumination or occlusion of other components, a polar coordinate transform and smoothness selection based circular mark point location method is proposed. The TR components are fundamental chips in electronic products and have various package types. The illumination changes, background disturbance, and the diversity of package types have imposed great challenges on the development of the uniform algorithm for detection and location of TR components. To deal with these issues, the 1-D integral image based TR component detection and location algorithm is proposed and the coordinates and orientation of the component are calculated simultaneously. The efficiency of the proposed methods is tested on real images and compared with classical Hough transform method, commercial algorithms on SMT482 device, and two methods of Halcon software.

Superhydrophobic surfaces – driven from natural biology – are being increasingly studied in many engineering fields. This study fabricated hydrophobic AAO/Ni coatings and superhydrophobic AAO/Ni/Ni...

The size effect on the activity of a catalyst has been a focal issue since ideal catalysts were pursued, whereas that on the degradation of a catalyst, by reaction intermediates such as CO, is little discussed. We demonstrate that the dehydrogenation of methanol-d4 on supported Rh nanoclusters precovered with CO (Rh-CO clusters) was obstructed, indicated by a decreased production of CO and D2; the obstructive effect exhibits a remarkable dependence on the cluster size, with a minimum at a cluster diameter near 1.4 nm. The decreased production arose from a decreased reaction probability controlled by the increased activation energy for each dehydrogenation step (including formation of methoxy-d3), adsorption energies of CO, and repulsion from the CO array on the Rh-CO surface. The effects of these factors in deactivating the clusters varied separately with the cluster size. Consequently, the size effect on the CO poisoning should be taken into account in engineering the cluster size to optimize the catalytic performance.

Annealed Rh nanoclusters on an ordered thin film of Al2O3/NiAl(100) were shown to exhibit a promoted reactivity toward the decomposition of methanol-d4, under both ultrahigh vacuum and near-ambient-pressure conditions. The Rh clusters were grown with vapor deposition onto the Al2O3/NiAl(100) surface at 300 K and annealed to 700 K. The decomposition of methanol-d4 proceeded only through dehydrogenation, with CO and deuterium as products, on Rh clusters both as prepared and annealed. Nevertheless, the catalytic reactivity of the annealed clusters, measured with the production of either CO or deuterium per surface Rh site from the reaction, became at least 2–3 times that of the as-prepared ones. The promoted reactivity results from an altered support effect associated with an annealing-induced mass transport at the surface. Our results demonstrate a possibility to practically prepare reactive Rh clusters, regardless of the cluster size, that can tolerate an elevated reaction temperature, with no decreased reactivity.

During the production process of electronic products, the accuracy of chip component placement on printed circuit boards is crucial and directly affects the realization of product functions. This article introduces a rectangular pin part positioning method based on point set registration to obtain the exact position of the chip component during the placement process. The model point set is built from the component’s datasheet. The feature points extracted from the component image are filtered according to the structure feature and the reckon angle to construct a data point set. A rigid point set registration algorithm is used to solve the alignment problem between these two point sets to obtain the offset and rotation angle. Compared with the Halcon algorithm, the Samsung method, and the state-of-the-art method, the positioning results show an advantage.

Microbial electrochemical systems (MESs) can be incorporated with membrane filtration that assists the bioelectrochemical treatment. Herein, a dynamic membrane (DM) was created on the carbon cloth-based anode electrode in a dynamic membrane microbial electrochemical system (DMES) and evaluated for treating domestic wastewater. The advantage of this DMES was demonstrated via comparing to the one without DM filtration. It was found that DMES achieved a current density of 15.75 ± 0.86 A m−3 at 10 Ω, which is significantly higher than that of the control system with no DM filtration (6.60 ± 0.22 A m−3). Moreover, the DMES effluent had a turbidity of 11.1 ± 0.3–16.7 ± 0.5 NTU under the varied water fluxes, which is much lower than that from the control system (29.3 ± 0.8–34.8 ± 0.5 NTU). The use of a stainless-steel current collector as a part of DM could increase the current generation. However, adding one more layer of DM showed a limited improvement of the DMES performance at the expense of an additional capital cost. When fed with actual domestic wastewater for an extended operation for 30 days, DMES showed relatively stable treatment performance and was able to maintain turbidity lower than 5 NTU. This study has provided the initial results of employing the DM concept in the anode of an MES for enhanced treatment performance and electricity generation. Several challenges to be addressed were identified and discussed with further investigation.

Aiming at the oscillation suppression of spacecraft with large flexible appendages, we propose a control strategy using H∞ control. The weighting functions are designed for the specific flexible modes of the spacecraft and the frequency of harmonic interference in its operating environment. Taking into account the structural uncertainty of systematic modeling and the comprehensive performance requirements of system bandwidth constraint and attitude stability, the H∞ comprehensive performance matrix is constructed. A space telescope with a large flexible solar array is presented as an illustrative example, and a control design that meets the requirement for pointing accuracy is proposed. The simulation results show that the designed controller satisfies the requirements of attitude stability and high pointing accuracy and has effectively suppressed the disturbance of endemic frequency. The design scheme and selection method of the weight function shown in this paper can be a reference for the controller design for oscillation suppression of this type of spacecraft with flexible structures.

It is very important for swimming coaches to analyse a swimmer’s performance at the end of each race, since the analysis can then be used to change strategies for the next round. Coaches rely heavily on statistics, such as stroke length and instantaneous velocity, when analysing performance. These statistics are usually derived from time-consuming manual video annotations. To automatically obtain the required statistics from swimming videos, we need to solve the following four challenging computer vision tasks: swimmer head detection; tracking; stroke detection; and camera calibration. We collectively solve these problems using a two-phased deep learning approach, we call Deep Detector for Actions and Swimmer Heads (DeepDASH). DeepDASH achieves a 20.8% higher F1 score for swimmer head detection and operates 6 times faster than the popular Faster R-CNN object detector. We also propose a hierarchical tracking algorithm based on the existing SORT algorithm which we call HISORT. HISORT produces significantly longer tracks than SORT by preserving swimmer identities for longer periods of time. Finally, DeepDASH achieves an overall F1 score of 97.5% for stroke detection across all four swimming stroke styles.

The corrosion behavior of an ultralow iron nickel-based alloy Inconel 625 under high-temperature water has been evaluated. The results show that surface oxidation and pitting were the principal corrosion mechanisms of Inconel 625 during the initial immersion period. The surface layer of the oxide film is first Ni-enriched and then Fe-enriched as immersion time increases. The iron ions dissolved from the autoclave could lead to the formation of NiFe2O4 and have a great influence on the oxidation behavior of Inconel 625. The oxides nucleated by solid-state reactions with selective dissolution of Fe and Ni and then grew up through precipitation of cations from solution.

The numerical simulation was conducted to investigate the coupling effects of H2 and CO2 on the laminar flame speed and reaction pathways of the biogas-hydrogen mixtures. The same proportions of H2 and CO2 were considered in the study. The dilution effects, chemical effects and thermal effects of H2 and CO2 were isolated, while the contributions of different effects were also calculated to identify the dominating factor. The results show that H radical pool plays the important role in the variation of laminar flame speed of biogas-hydrogen mixture. The coupling dilution effects of H2 and CO2 lead to the considerable decrease of H radical and dominate the decreased laminar flame speed. The H2 chemical effects improve R84 (OH + H2 = H2O + H) and R3 (O + H2 = H + OH) quite effectively, which results in the reduced dropping trends of H radical and laminar flame speed from BG60H40 to BG40H60. The CO2 chemical effects suppress the major H radical production reactions of R84, R3, R99 (OH + CO = H + CO2) and R10 (O + CH3 = H + CH2O) more apparently at the fuel-rich condition, while importance of major consumption reactions (R53: H + CH4 = CH3+H2, R52: H + CH3(+M) = CH4(+M) and R58: H + CH2O = HCO + H2) are higher at the fuel-rich condition. This dominates the more evident decrease of H radical and laminar flame speed at the fuel-rich condition. Based on the ROP analysis, R3, R46 (H + HO2 = 2OH), R52, R84, R99 and R158 (2CH3(+M) = C2H6(+M)) have the major contributions on the chemistry transition caused by the coupling effects of H2 and CO2. The decreased contribution of R158 and R99 indicate the weakened CH4-related chemistry while the increased contributions of R3, R46, R52 and R84 indicate the improved H2-related chemistry in the biogas-hydrogen flame. Furthermore, coupling effects of H2 and CO2 or H2/CO2-related chemistry can be monitored by the contribution variations of R84 and R99 on the OH radical concentration.

Increased generation of spent lithium-ion batteries (LIBs) has driven the exploration of new methods for reusing and/or recycling LiCoO₂ cathode materials. Herein, an electrochemical relithiation method was proposed to directly regenerate LiCoO₂ cathode materials using the waste LiₓCoO₂ electrode as a base. It was shown that Li⁺ was successfully inserted into the waste LiₓCoO₂ electrode, and this relithiation process became faster with either a higher Li₂SO₄ concentration or a higher cathodic current density. The XRD analysis confirmed that the peak positions of the relithiation products were consistently close to those of a standard LiCoO₂ material. The crystal structure of the relithiation products was restored with a post-annealing process. The activation energy for electrochemical relithiation (Eₐ) was estimated at 22 kJ mol–¹, and the constant of equilibrium constant k₀ was determined as 1.35 × 10–⁶ cm s–¹. The relithiation process was controlled by the charge transfer process when the Li₂SO₄ concentration was high (e.g., 1, 0.8, and 0.5M), and a lower concentration at 0.01–0.3 M led to a diffusion control pattern. The electrode made of the regenerated LiCoO₂ materials had a charge capacity of 136 mAh g–¹, close to that of the commercial LiCoO₂ electrode (140 mAh g–¹). A potential mechanism of electrochemical relithiation was proposed involving lithium defects, relithiation, and crystal regeneration.

Electric power steering (EPS) systems are prone to oscillations because of a very small phase angle margin, so a stable controller is required to increase the stability margin. In addition, the EPS system has parameter disturbances in the gain of the torque map under different conditions, which requires a certain degree of robustness in the control design. This paper synthesizes the multidimensional performance requirements considering the stability margin, robustness, and bandwidth of the system to form an H∞ optimization matrix with multidimensional performance output in using the structured H∞ control design. The structured H∞ controller not only retains the characteristics of traditional H∞ controllers with excellent robust performance and high stability margin but also has a lower order, which can be better applied in practice. Based on the performance requirements of the system and practical implementation, the structured H∞ controllers with different orders were designed, and the feasibility of the structured controller was confirmed through comparison and theoretical analysis.

A series of LiNi0.5-xCuxMn0.5O2 (0 ≤ x ≤ 0.05) samples were synthesized through a combination of co-precipitation (CP) and solid-state reaction. The synthesized cathode materials were systematically investigated by X-ray diffraction (XRD), Rietveld refinement, inductively coupled plasma (ICP) spectroscopy, X-ray photoelectron spectroscopy (XPS), and charge-discharge tests. The structural measurements indicated that Cu2+ was successfully doped into the structure of the LiNi0.5Mn0.5O2 material. The results of the electrochemical measurements suggest that the electrochemical performances of LiNi0.5Mn0.5O2 can be obviously improved by Cu -doping, and the best doping amount is 1 mol%. Specifically, the capacity retention of a 1 mol% Cu-doped sample is 18% higher than that of pure LiNi0.5Mn0.5O2 in the range of 2.5~4.6 V at 0.2 C. Most importantly, the cycle stability of LiNi0.5Mn0.5O2 at high currents can also be improved by Cu-doping. We found that Cu-doping can lower the Li/Ni cation mixing, enlarge the migration channels of lithium ions, reduce migration resistance, and retard polarization, and in turn, it can improve the electrochemical properties of LiNi0.5Mn0.5O2.

The limited amount of electron mediators (EMs) excreted by microorganisms has restricted electricity generation and the related pollutant removal in microbial fuel cells (MFCs). The polyphenolic-rich plants contain simple polyphenols or anthraquinones that have promising electron-shuttling potential, but this has not been well understood. Herein, four herbal plants Polygonum multiflorum (T. fallopia), rhubarb (B. rheum), radix rubiae (L. Rubia) and semen cassiae (Catsia tora Linn) were selected and then studied to produce EMs to stimulate electricity generation in MFCs. B. rheum had the highest redox activity and 2% acid pretreatment contributing the most to the release of electroactive substances. The highest power density (18.67 W/m3) and Coulombic efficiency (29.03%) and the lowest internal resistance (29.02 Ω) were achieved in MFCs with B. rheum addition compared to other herbal plants. The satisfactory COD (93.68%) and NH4+-N (39.68%) removal were also obtained with a 0.01 g/L dosage. Confocal laser scanning microscopy and high throughput sequencing analysis showed that B. rheum had the least negative effects on biofilm microstructure and microbial species, corresponding to its outstanding performance. These findings first suggested that B. rheum can be regarded as a promising redox mediator to improve MFC performance. This study provided a new thinking to apply herbal wastewater or pharmaceutical waste in improving the bioelectrochemical system.

The nano SiC coatings were prepared on the surface of graphite by laser irradiation under different laser energy densities (7.07–14.15 kJ/cm2). The influence of laser energy density on the structure and quality of coatings was systematically investigated. The results show that laser irradiation can transform the preset micron-SiC particle coating into nano-SiC particle coating. The nano-SiC coating prepared by laser irradiation can effectively enhance the high temperature oxidation resistance of the graphite substrate. When the laser energy density is 7.07 kJ/cm2, the prepared coating displays a single crystal structure and a good morphology without cracks and spheroidization. The coating prepared under the laser density of 10.61 kJ/cm2 shows a mixed crystal structure with obvious spheroidization. Further increase the laser energy density to 14.15 kJ/cm2, the main structure of prepared coating turns to polycrystalline and obvious cracks can be observed. The cross-section analysis of coating prepared under laser energy density of 7.07 kJ/cm2 indicates that there existed elemental diffusion between the coating and the substrate which increased the adhesion of coating. The calculations based on the Arrhenius formula present that this prepared coating has higher activation energy and therefore it has better high temperature oxidation resistance than the other prepared coatings.

Cu–Sn–Zn (CSZ) coatings are widely applied in communication devices due to their excellent performance in electrical/thermal conductivity, solderability, and corrosion resistance. Particularly, a novel TiO2–sol-enhanced electrodeposition method has been proposed to prepare CSZ–TiO2 nanocomposite coatings with different volume fractions of TiO2–sol. A series of CSZ–TiO2 nanocomposite coatings were prepared in the current study. The crystal phase, surface morphology, and micro- to nanostructures of sol-enhanced nanocomposite coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Based on the prior research, we studied the microhardness, surface friction behavior, and corrosion behavior of the coatings. Our results indicate that adding 12.5 mL L−1 TiO2–sol increased the average microhardness of CSZ coating from 325 to 421 HV and reduced the corrosion rate by 42.8%. Those results reveal that the TiO2–sol affected the performance of CSZ coatings depends on the volume added. Additionally, we investigated the effects of TiO2–sol volume fraction on the morphology, microhardness, dry sliding wear-resistant capability, and corrosion-resistant capability.

Rechargeable magnesium ion batteries are potential candidates to replace the lithium ion batteries due to their high volumetric energy density, dendrite free cycling, and low costs. In present work, we have critically reviewed the recent advances made in the field of cathode materials development to achieve the high reversible capacities and working potentials. In first part, carbon-based cathodes such as fluorine-doped graphene nanosheets and graphite fluoride (CF0.8) are discussed in terms of compatibilities of positive electrode materials and electrolyte solutions for rechargeable magnesium-ion batteries. Whereas, the second part of this review focuses on crystal structure of vanadium oxide and its capability to accommodate the Mg2+ ions. Likewise, electrochemical performance of selected vanadium oxide based cathodes including VO2 (B), FeVO4.0.9H2O, Mo2.5+yVO9+δ, RFC/V2O5 and V2O5/Graphene composite, are discussed at different temperatures. To support the future research on magnesium ion batteries, particularly positive electrode material developments, several innovative research directions are proposed.

Interatomic potential plays an important role in molecular dynamics simulation, which determines both the efficiency and accuracy of the simulations. Lattice inversion is a method which can be used to develop interatomic potential from first principle results directly. In present work, a robust potential model based on lattice inversion is proposed. Then the potential model is applied to develop interatomic potentials for eight common FCC metals. The cohesive energy curves calculated using first principle calculations can be well reproduced, which verifies the reliability of the developed potential. Additional physical properties, including equilibrium lattice constant and cohesive energy, elastic constants, are predicted and found reasonable agreement with corresponding first principle results.

Flue gas carbonation of three commonly used cement-based building products, concrete masonry blocks, cement-bond fiberboards and cement-bond bead boards, was studied to investigate the feasibility of using as-captured cement kiln flue gas to accelerate hydration and store carbon dioxide for emission reduction. Compared to pure gas carbonation, the use of flue gas does not require chemical separation which is energy-intensive. However, the reaction efficiency was low because of low CO2 concentration in flue gas. It could take up to two weeks to achieve required strength. This paper presents an innovative process in which flue gas carbonation was carried out in 5 h with 7 cycles of injection and release. Cement-based building products could achieve 5-6% CO2 uptake independent from types of products. Compared to pure gas carbonation, degree of carbonation was low in flue gas but strength gain was in the same order of magnitude. Reaction product was typical calcium silicate carbo-hydrates, a carbonate modified hydrate. The size of carbonate crystal was much smaller by flue gas carbonation. However, their contribution to strength gain was comparable to larger crystals in pure gas carbonation. The successful capture and utilization of cement kiln flue gas made it feasible to establish a network to link cement plants (CO2 sources) to concrete plants (CO2 sinks) for emission reduction through utilization.

The current work mainly investigates the corrosion resistance and conductivity of TiN layer on Ti–6Al–4V with liquid phase plasma electrolytic nitridation for PEMFC bipolar plate (BP). The X-ray diffraction (XRD) results show that TiN phase presents in the nitriding samples. The surface morphology analysis indicates that higher CH4NO2 concentration tends to form more compact structure. The potentiodynamic polarization test indicates that sample N-600 prepared by 600 g/L CH4NO2 concentration possesses the lowest corrosion current density of 0.57 μA cm−2 in the simulated PEMFC cathode potential (+0.6 VSCE), which completely satisfies the DOE 2020 technical targets. Meanwhile, sample N-600 also exhibits the highest corrosion resistance and stability in the potentiostatic polarization, electrochemical impedance spectroscopy (EIS) and high potential (+1.6 VSCE) polarization test. Interfacial contact resistance (ICR) results show that sample N-600 possesses the lowest ICR value of 6 ± 0.4 mΩ cm2, which fully meets the DOE 2020 requirements.

Developing efficient charge separation strategies is essential to achieve high-power conversion efficiency in the fields of chemistry, biology, and material science. Herein, we develop a facile strategy for fabrication of unique wafer-scale radial nanowire assemblies by exploiting shear force in rotary solution. The assembly mechanism can be well revealed by the large-scale stochastic dynamics simulation. Free electrons can be rapidly generated to produce quantitatively tunable current output when the radial nanowire assemblies rotate under the magnetic field. Moreover, the photoconductive performance of the radial semiconductor nanowire assemblies can be remarkably enhanced as the electron-hole recombination was retrained by the efficient charge separation under the rotating magnetic field. Such large-scale unique nanowire assemblies will facilitate the design of an efficient charge separation process in biosystem, sensors, and photocatalysis.

The rechargeable magnesium ion batteries (MIBs) are ideal candidates to replace currently commercialized high energy density lithium ion batteries (LIBs) owing to their cost effective and environmentally friendly nature. However, bad performance of MIBs is a big challenge for researchers. In this review, we have critically discussed the state-of-the-art research activities made for the development of Mg-ion battery electrolytes and cathode materials with fast magnesiation kinetics. Emphasizing the chemical structures of both organic and inorganic electrolytes and their compatibilities with different cathode materials, the kinetic properties of electrochemical reactions for achieving optimized energy and power densities, are critically reviewed. To tackle the large polarizations of MIBs, the latest and emerging hybrid ion electrochemistries such as Mg–Li, Mg–Na, aqueous rechargeable Mg–Na, and Mg–Zn hybrid ion batteries, are highlighted to elaborate the merits and challenges of each electrolyte and nanostructured cathodes. The cathode materials covered in this review include various kinds of inorganic materials (i.e. metal oxides, metal sulfides), organic polymers, Prussian blue analogous and NASICON-type Li/Na cathodes with high working potentials. At the end, this review discuss comprehensive future research strategies for exploring new cathodes with high working voltages for MIBs.

Hospital service quality (HSQ) evaluation is seriously challenged due to the uncertainties of evaluators’ subjective perception and the choice of evaluation methods. A new HSQ evaluation framework ...

The electrolyte, one of the key components for the energy storage in the vanadium redox flow battery (VRFB), hinders the further commercial applications of the VRFB due to the poor thermal stability of the positive electrolyte at the elevated temperature and the inferior activity on the interface of electrode. To enhance the performance of the positive electrolyte, a zwitterion-type molecule pyridinium propyl sulphobetaine (PPS) with negatively charged sulfonic group and positively charged pyridine group is adopted as the additive for the positive electrolyte. In this study, we have proved that PPS can be adsorbed on the electrode through sulfonic group and pyridine group under both positive potential and negative potential, which can effectively modify the interface of electrode. Compared to other additives containing –NH2/–SO3H groups, PPS containing pyridine group may effectively eliminate the side effects of protonation (–NH3+) and intermolecular hydrogen bonding (-SO3−---+H3N-) in acidic electrolyte. Moreover, the PPS-containing V(V) electrolyte presents a better stability at 50 °C compared to the blank V(V) electrolyte. As a consequence, with the addition of 1% PPS in positive electrolyte, the VRFB exhibits higher efficiencies (80.78% VE and 78.17% EE compared to 78.95% VE and 76.87% EE of the blank VRFB at 100 mA cm−2) and 76.28% capacity retention after 100 cycles which is 5.22% higher than that of the pristine VRFB. Herein, the study of zwitterion molecules provides a meaningful reference for the further research on organic additives for VRFB.

Bioelectrochemical systems (BESs) have been intensively studied in the past decade, but precise understanding of BESs performance is hindered by unclear definition of several key parameters. Herein, we analyze and discuss three sets of terms about conversion efficiency, energy performance, and pilot scale. It is suggested that ‘Coulombic recovery’ can avoid the misleading results because of different organic removals, compared with ‘Coulombic efficiency.’ Power density is not a suitable term to describe energy performance of BESs, and energy production/consumption should be reported in the energy unit such as kWh. Pilot-scale BESs should meet several criteria, including hydraulic capacity, use of actual wastewater, non-laboratory condition, and long-term operation. Proper use of those terms is strongly encouraged and will be critically important to BESs research and development.

Waste heat from anaerobic digesters can be converted to electricity by using thermoelectric generators (TEG). Herein, such energy was employed to power a microbial electrolysis cell (MEC) for producing hydrogen gas. Four TEG units could deliver a voltage of ~0.5 V, sufficient to drive the MEC that achieved a hydrogen production rate of 0.48 ± 0.13 m3 m−3 d−1. This rate was further improved to 0.75 ± 0.05 m3 m−3 d−1 when the temperature difference for TEG was increased from 18 to 28 °C. There was no significant difference between the TEG-powered MEC and power supply-supported MEC (at 0.6 V), in terms of current generation, hydrogen production, and organic removal. Ambient air was also studied as a cold-side source for TEG, although some challenges were encountered to maintain a large temperature difference. Those results will encourage further exploration of using TEG as a feasible power supply for sustainable MEC operation.

In this work, a method has been presented to analyze the influence of control saturation and structural flexibility on the stable radius of highly flexible aircraft. A dynamic model of aircraft is constructed followed by the analysis of kinetic characteristics. In this paper, the closed-loop stability boundary of highly flexible aircraft with open-loop instability is studied. The amplitude limit and bandwidth limit of the control signal are considered in the closed-loop stability boundary calculation. Our analysis shows that the boundary is related to the left eigenvector corresponding to the unstable poles and the amplitude constraint of the control signals. Stability of the boundary of feedback control system further reduces the limitation of the bandwidth of actuators. Focused on the phugoid instability of highly flexible aircraft, computational formulation of the closed-loop stable boundary is achieved. The Monte Carlo analysis has been employed to validate the stable region, under the LQR controller. Both the theory and simulations have nice correlations with each other which verify the stability of the closed-loop system, restricted by the open-loop system, and the influence of control signal bandwidth constraints.

The effects of heat treatment on the properties of electrodeposited Co–P–TiO2 nanocomposite coatings were systematically investigated. The TiO2 nanoparticles-reinforced Co–P–TiO2 nanocomposites wer...

Forward osmosis (FO) has shown advancement towards recovery of useful water from various waste streams. A major issue that arises is the accumulation of salts due to reverse solute flux (RSF) from a draw solution into a feed solution that can result in several negative effects such as decreased water flux and inhibition of biological activities. This paper aims to provide a concise discussion and analysis of methods that can help to alleviate the effects of solute buildup. New parameters, solute removal/recovery rate (SRR) and removal/recovery ratio (ReR), are proposed to help better define the performance of reducing solute buildup and employed in case studies to evaluate selected reduction methods. Solute removal can be accomplished by physical separation, chemical precipitation, and biological removal. Recovery of solutes, one step beyond removal, is discussed and demonstrated by using bioelectrochemical systems and electrodialysis as examples. This work has highlighted the concerns associated with solute buildup and will encourage further exploration of effective tools to mitigate solute buildup for improved performance of FO-based water/wastewater systems.

Some neurons in the primary visual cortex (V1) of human visual system (HVS) conduct dynamic center-surround computation, which is thought to contribute to compress the high dynamic range (HDR) scene and preserve the details. We simulate this dynamic receptive field (RF) property of V1 neurons to solve the so-called tone mapping (TM) task in this paper. The novelties of our method are as follows. (1) Cortical processing mechanisms of HVS are modeled to build a local TM operation based on two Gaussian functions whose kernels and weights adapt according to the center-surround contrast, thus reducing halo artifacts and effectively enhancing the local details of bright and dark parts of image. (2) Our method uses an adaptive filter that follows the contrast levels of the image, which is computationally very efficient. (3) The local fusion between the center and surround responses returned by a cortical processing flow and the global signals returned by a sub-cortical processing flow according to the local contrast forms a dynamic mechanism that selectively enhances the details. Extensive experiments show that the proposed method can efficiently render the HDR scenes with good contrast, clear details, and high structural fidelity. In addition, the proposed method can also obtain promising performance when applied to enhance the low-light images. Furthermore, by modeling these biological solutions, our technique is simple and robust considering that our results were obtained using the same parameters for all the datasets (e.g., HDR images or low-light images), that is, mimicking how HVS operates.

Two-dimensional (2D) metal–organic frameworks (MOFs) and their derivatives with excellent dimension-related properties, e.g. high surface areas, abundantly accessible metal nodes, and tailorable structures, have attracted intensive attention as energy storage materials and electrocatalysts. A major challenge on the road toward the commercialization of 2D MOFs and their derivatives is to achieve the facile and controllable synthesis of 2D MOFs with high quality and at low cost. Significant developments have been made in the synthesis and applications of 2D MOFs and their derivatives in recent years. In this review, we first discuss the state-of-the-art synthetic strategies (including both top-down and bottom-up approaches) for 2D MOFs. Subsequently, we review the most recent application progress of 2D MOFs and their derivatives in the fields of electrochemical energy storage (e.g., batteries and supercapacitors) and electrocatalysis (of classical reactions such as the HER, OER, ORR, and CO2RR). Finally, the challenges and promising strategies for the synthesis and applications of 2D MOFs and their derivatives are addressed for future development.

The characteristic of a flexible system with weak damping is that the amplitude characteristics show a large change, and the situation on the Nyquist chart is extremely complicated. Due to the existence of weak damping, the perturbation range of the flexible modal parameters allowed by the system is greatly compressed, and the robust stability is reduced, which brings challenges to the control design. To deal with this problem, the traditional H-inf loop shaping method often leads to the controller instability and poor robustness. In order to improve the stability margin of the system, increase the robustness and stability, and solve the problem of the instability of H-infcontrollers, this paper proposes a robust comprehensive design method based on phase control. In this method, by using the closed-loop pole configuration corresponding to the flexible mode at low frequency, the phase control is realized. Through the phase control, the apex of the Nyquist curve of the weakly damped mode of the system is limited to the Right half plane. The H-inf weighting function relaxes the pole configuration requirements, reduces the conservativeness of strict positive real, and combines the phase control with the H-inf optimization solution to obtain a robust and self-stable H-inf controller. A specific design example is given. The simulation results show that this control method has extremely high robustness. This design example can provide a certain degree of robust design for other weakly damp.

The development of nonprecious metal-nitrogen-carbon (M-N-C) materials with efficient metal utilization and abundant active sites for the oxygen reduction reaction (ORR) is of great significance for fuel cells and metal-air batteries. Ultrasmall 2 D Cox Zn2-x (benzimidazole)4 [Cox Zn2-x (bim)4 ] bimetallic metal-organic framework (MOF) nanosheets (≈2 nm thick) are synthesized by a novel bottom-up strategy and then thermally converted into a core-shell structure of sub-5 nm Co nanodots (NDs) wrapped with 2 to 5 layers of Co,N-codoped graphene (Co@FLG). The size of the Co NDs in Co@FLG could be precisely controlled by the Co/Zn ratio in the Cox Zn2-x (bim)4 nanosheet. As an ORR electrocatalyst, the optimized Co@FLG exhibits an excellent half-wave potential of 0.841 V (vs. RHE), a high limiting current density of 6.42 mA cm-2 , and great stability in alkaline electrolyte. Co@FLG also has great ORR performance in neutral electrolyte, as well as in Mg-air batteries. The experimental studies and DFT calculations reveal that the high performance of Co@FLG is mainly attributed to its great O2 absorptivity, which is endowed by the abundant Co-Nx and pyridinic-N in the FLG shell and the strong electron-donating ability from the Co ND core to the FLG shell. This elevates the eg orbital energy of CoII and lowers the activation energy for breaking the O=O/O-O bonds. This work sheds light on the design and fabrication of 2 D MOFs and MOF-derived M-N-C materials for energy storage and conversion applications.

A series of Co–P–TiO2 nanocomposite coatings were prepared via pulsed electrodeposition technique. TiO2 nanoparticles were embedded into the coating matrix using TiO2 sol. The phase constituents of...

Warranty claims forecasting plays an increasingly important role not only for preparing financial plans but also for optimizing warranty policy and improving after-sale services. In the case of new products, an important feature is that the new generation of products often has a close connection with the previous generations of products it replaces. Thus, the warranty claims data of the previous generations of products can be used for extracting reliability information of new products. In this context, we propose a warranty claims forecasting model considering usage rate for new products sold with a two-dimensional warranty. The accelerate failure time model is introduced to investigate the effect of usage rate on product degradation. The non-homogeneous Poisson process is used to model failure counts of repairable products and the constrained maximum likelihood estimation method is used to estimate model parameters. The results of data experiments based on both simulation and real data collected from an automobile manufacturer in China show that the proposed model considering the varying usage rate outperforms the traditional models in forecasting the number of warranty claims.

University-utility partnerships (UUPs) are mutually beneficial collaborations that promote and accelerate innovation in the water sector. The Leaders Innovation Forum for Technology (LIFT) program worked with representatives from universities and utilities to define successful methods and strategies for establishing strong university-utility collaborative partnerships. Overall, partners in a successful university-utility collaboration need to be honest and realistic to match university capabilities and utility needs. In order to manage expectations at both organizations, utilities and universities must understand their respective points of view. Building and maintaining strong relationships should be a primary concern. Successful UUPs are built upon strong relationships between organizations rather than just strong research ideas. Different implementation structures should be considered for UUPs depending on what works best for both organizations. Common hurdles to overcome when implementing UUPs include working across distances and managing risks related to financing, intellectual property, and public outreach. PRACTITIONER POINTS: University-utility collaborative partnerships are mutually beneficial and promote innovation throughout the water sector as a whole Establishing successful partnerships can be challenging, but difficulties can be mitigated by following the described best practices Partnerships can be structured and implemented in a variety of ways depending on the specific needs of each organization involved.

Due to the complex outsourcing characteristics of aviation equipment development, one key issue is how to coordinate quality and cost decisions during development. This article focuses on the quali...

Direct electrochemical reduction of CO2 to multicarbon products is highly desirable, yet challenging. Here, we present a potentiostatic pulse-electrodeposition of high-aspect-ratio CuxAuy nanowire arrays (NWAs) as high-performance electrocatalysts for the CO2 reduction reaction (CO2RR). The surface electronic structure related to the Cu:Au ratio in the CuxAuy NWAs could be facilely modulated by controlling the electrodeposition potential and the as-fabricated CuxAuy NWAs could be directly used as the catalytic electrode for the CO2RR. The morphology of the high-aspect-ratio nanowire array significantly lowers the onset potential of the alcohol formation due to the diffusion-induced enhancement of the local pH and CO concentration near the nanowire surface. Besides, the properly adjusted surface electronic structure of the CuxAuy NWA enables the adsorption of CO and facilitates the subsequent CO reduction to ethanol via the C-C coupling pathway. Owing to the synergistic effect of morphology and electronic structure, the optimized CuxAuy NWA selectively reduces CO2 to ethanol at low potentials of −0.5–−0.7 V vs. RHE with a highest Faradaic efficiency of 48%. This work demonstrates the feasibility to optimize the activity and selectivity of the Cu-based electrocatalysts toward multicarbon alcohols for the CO2RR via simultaneous adjustment of the electronic structure and morphology of the catalysts.

We consider a supply chain with one supplier providing basic products to two risk-averse retailers. Each retailer provides a warranty policy for the products to differentiate their products along with pricing strategy. Considering that the risk-aversion level of each retailer is private in most applications, we assume that the retailers’ risk-aversion levels are their respective private information in this paper. Each retailer may choose to disclose her private risk-aversion information to the supplier. We explore the risk-aversion information revelation mechanism of the retailers and propose the supplier’s decisions on whether to accept the revealed information. Our results show that the warranty period added to the product by each retailer is only related to each retailer’s warranty cost efficiency and the consumers’ sensitivity toward warranty. Each retailer is willing to share her risk-aversion level with the supplier only when the real value of her risk-aversion level is lower than the mean value of other participants’ estimation under both the no information leakage scenario and the information leakage scenario. Furthermore, we find that the information leakage has a negative effect on the supplier’s profit if he accepts the shared risk-aversion information.

In this study, Ni–P, Ni–W–P and Ni–B coatings were electrolessly plated on aluminium alloy substrates. All coatings were uniform and adherent with shiny metallic appearances. A systematic study was...

Nowadays, fierce competition and increasing customer requirements force manufacturers to continuously provide better after-sales services and supports. One such kind of after-sales services is product warranty which has been offered for almost all products in today’s market. In this paper, we study a new warranty policy, called piece-wise renewing free replacement warranty. Under this policy, the whole warranty period is divided into two sub-periods and once an item fails in a specific sub-period, it will be replaced by a new identical one and the warranty period is fully or partially renewed. The expected warranty cost and warranty cycle of this policy are derived from the manufacturer’s perspective. The proposed model is then modified by involving three sub-periods and a failure limit, respectively. In the latter scenario, when the number of item failures over a warranty cycle exceeds a pre-specified threshold, the manufacturer has to refund the item’s purchase price, and consequently the warranty ceases. A real-world case study is presented using warranty data of a battery manufacturer. It is found that for a given warranty period, the piece-wise renewing free replacement policy has a better performance than traditional fully renewing policy, in terms of expected warranty cost, warranty cycle, and cost rate.

Catalysts are critically important to accomplish hydrogen evolution reaction in microbial electrolysis cells (MECs). Herein, palladium nanoparticles were generated directly on a cathode electrode by bioelectrochemical reduction with Shewanella oneidensis MR-1 and then applied to produce hydrogen gas in MECs. The MEC with bioelectrochemically deposited Pd catalysts achieved a hydrogen production rate of 61.8 ± 2.0 L-H2 m−3 d−1, significantly higher than 38.5 ± 2.0 L-H2 m−3 d−1 with the Pd catalysts in the absence of microbial reduction. This improvement was related to a higher electrochemical active surface area of 40.5 ± 3.5 m2 g−1 and smaller Pd particle size (10–100 nm) on the cathode with bioelectrochemical deposition, compared to those of electrochemically-generated Pd catalysts (16.8 ± 2.8 m2 g−1 and 200–250 nm, respectively). The superior performance of the bioelectrochemically deposited Pd catalysts was supported by a much smaller charge transfer resistance of 15.4 Ω. Although microorganisms could help generate better Pd catalysts, the lack of strong bond between Pd nanoparticles and carbon cloth resulted in unstable hydrogen production performance. Applying a binding agent – Nafion led to consistent current generation and hydrogen production. The results of this study encourage further exploration of in situ deposition of catalysts via bioelectrochemical reactions for MEC applications.

Three kinds of IT-like non-fullerene electron acceptors, acting as electron transport layer, were introduced into the inverted perovskite solar cell. Based on systemically adjusting the thickness of the electron transport layer, the devices with three indacenodithieno[3,2-b]thiophene (IT) like (IT-like) non-fullerene acceptors wholly performed better superiority than that based on phenyl-C61-butyric acid methyl ester (PCBM), and a high efficiency of 14.29% was achieved by the device with ITIC electron transport layer. Comparing the detail parameters, the open-circuit voltage is all enhanced because the recombination loss is further suppressed with PCBM replacing by IT-like non-fullerenes. More importantly, the IT-like non-fullerenes show an unparalleled ability in extraction and transportation of photo-generated carrier and the radiation loss is largely inhabited. Benefits from the high quality perovskite film, lower recombination loss and trap passivation, the abnormal hysteresis effect is dramatically suppressed by IT-like non-fullerenes. By comparing with PCBM based devices, the hysteresis index (HI) of the inverted PSCs based on ITIC, ITIC-Th and IT-M are 1.78, 1.35, 1.83 and reduced by 47%, 46% and 60%, respectively. This work preliminary reveal the obvious advantage for the application of IT-like non-fullerenes in inverted perovskite solar cells, which shows great potential in preparing non-hysteresis, high efficient inverted perovskite solar cells.

Inverted planar perovskite solar cells (PSCs) with a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) layer as the hole transport layer (HTL) are shown to exhibit high power conversion efficiency (PCE). To date, efficient PTAA HTLs have required dopants to increase conductivity. These dopants, which include 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane and bis(trifluoromethane)sulfonimide lithium salt/4-tert-butylpyridine, are harmful to the stability of the devices and may increase the cost of the PSCs. We realized efficient inverted planar PSCs with nondoped PTAA as the HTL. We used contact angle, absorption spectra, X-ray diffraction, fluorescence spectra, and atomic force microscope to measure the impact of nondoped PTAA on the upper perovskite films. The results showed that the nondoped PTAAs work as effectively as the doped ones. The inverted planar PSCs based on nondoped PTAA exhibited relatively excellent performance. We achieved a higher PCE of 18.11% and a very small hysteresis index of 0.32% were using a very thin nondoped PTAA film. This efficient nondoped HTL provided an easy way for inverted planar PSCs to solve problems introduced by dopants. This study provides a reference for the future preparation of highly efficient and stable PSCs with nondoped HTL.

Planning of collision-free trajectory for robot motion under hard constraints and unpredictable environment is a difficult issue. To cope with this problem, this paper presents a novel replanning method based on receding horizon control and asymptotically optimal single-query motion planning. The approach, called the horizon-based lazy optimal rapidly-exploring random tree algorithm, enables real-time replanning in both static and dynamic environment with updated information. Previous feasible solutions are fully considered to generate new plans. Contributions include lazy steering and lazy collision checking search tree, forward tree pruning and sampling distribution online learning. The techniques are proven to be efficient, near optimal and fast responsive to change. Moreover, three experiments are performed to test the properties of the proposed algorithm numerically.