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Carbon materials have excellent catalytic effects on the hydrogen storage performance of MgH2. Here, carbon-supported Ni3S2 (denoted as Ni3S2@C) was synthesized by a facile chemical route using ion exchange resin and nickel acetate tetrahydrate as raw materials and then introduced to improve the hydrogen storage properties of MgH2. The results indicated the addition of 10 wt.% Ni3S2@C prepared by macroporous ion exchange resin can effectively improve the hydrogenation/dehydrogenation kinetic properties of MgH2. At 100 °C, the dehydrogenated MgH2 Ni3S2@C-4 composite could absorb 5.68 wt.% H2. Additionally, the rehydrogenated MgH2 Ni3S2@C-4 sample could release 6.35 wt.% H2 at 275 °C. The dehydrogenation/hydrogenation enthalpy changes of MgH2 Ni3S2@C-4 were calculated to be 78.5 kJ mol−1/−74.7 kJ mol−1, i.e., 11.0 kJ mol−1/7.3 kJ mol−1 lower than those of MgH2. The improvement in the kinetic properties of MgH2 was ascribed to the multi-phase catalytic action of C, Mg2Ni, and MgS, which were formed by the reaction between Ni3S2 contained in the Ni3S2@C catalyst and Mg during the first hydrogen absorption–desorption process.

Magnesium hydride (MgH2) is a potential material for solid-state hydrogen storage. However, the thermodynamic and kinetic properties are far from practical application in the current stage. In this work, two-dimensional vanadium carbide (V2C) MXene with layer thickness of 50−100 nm was fist synthesized by selectively HF-etching the Al layers from V2AlC MAX phase and then introduced into MgH2 to improve the hydrogen sorption performances of MgH2. The onset hydrogen desorption temperature of MgH2 with V2C addition is significantly reduced from 318 °C for pure MgH2 to 190 °C, with a 128 °C reduction of the onset temperature. The MgH2 + 10 wt% V2C composite can release 6.4 wt% of H2 within 10 min at 300 °C and does not loss any capacity for up to 10 cycles. The activation energy for the hydrogen desorption reaction of MgH2 with V2C addition was calculated to be 112 kJ mol−1 H2 by Arrhenius's equation and 87.6 kJ mol−1 H2 by Kissinger's equation. The hydrogen desorption reaction enthalpy of MgH2 + 10 wt% V2C was estimated by van't Hoff equation to be 73.6 kJ mol−1 H2, which is slightly lower than that of the pure MgH2 (77.9 kJ mol−1 H2). Microstructure studies by XPS, TEM, and SEM showed that V2C acts as an efficient catalyst for the hydrogen desorption reaction of MgH2. The first-principles density functional theory (DFT) calculations demonstrated that the bond length of Mg−H can be reduced from 1.71 A for pure MgH2 to 2.14 A for MgH2 with V2C addition, which contributes to the destabilization of MgH2. This work provides a method to significantly and simultaneously tailor the hydrogen sorption thermodynamics and kinetics of MgH2 by two-dimensional MXene materials.

Hydrogen can serve as a carrier to store renewable energy in large scale. However, hydrogen storage still remains a challenge in the current stage. It is difficult to meet the technical requirements applying the conventional storage of compressed gaseous hydrogen in high-pressure tanks or the solid-state storage of hydrogen in suitable materials. In the present work, a gaseous and solid-state (G-S) hybrid hydrogen storage system with a low working pressure below 5 MPa for a 10 kW hydrogen energy storage experiment platform is developed and validated. A Ti–Mn type hydrogen storage alloy with an effective hydrogen capacity of 1.7 wt% was prepared for the G-S hybrid hydrogen storage system. The G-S hybrid hydrogen storage tank has a high volumetric hydrogen storage density of 40.07 kg H2 m−3 and stores hydrogen under pressure below 5 MPa. It can readily release enough hydrogen at a temperature as low as −15 °C when the FC system is not fully activated and hot water is not available. The energy storage efficiency of this G-S hybrid hydrogen storage system is calculated to be 86.4%–95.9% when it is combined with an FC system. This work provides a method on how to design a G-S hydrogen storage system based on practical demands and demonstrates that the G-S hybrid hydrogen storage is a promising method for stationary hydrogen storage application.

In this paper, experiments were performed to investigate the coupling effects of venting and nitrogen addition ratio (χ) on flame behavior and pressure evolution during hydrogen–air deflagration within and outside a 1-m-high vertical duct with a vent on its top. Experimental results reveal that χ has significant effects on the pressure–time histories in the duct. Helmholtz oscillations of the internal overpressure were observed in all tests, and acoustic type oscillations appears in the tests only for χ = 25% and 30%. For a certain χ, the maximum overpressure (Pmax) increased with the distance to the vent, i.e., the highest overall explosion overpressure was attained near the duct bottom; however, the difference in Pmax between various measuring points decreases with an increase in χ. In all tests, a pressure peak in the duct was observed shortly after external explosion. The maximum internal and external overpressure decreased as χ was increased.

In this work, a Co9S8/NiS composite is successfully electrodeposited on Ni foam using a cyclic voltammetry method. This method is one of several effective strategies for the in-situ growth of self-supporting arrays for electrode material, which facilitates the effective combination of Co9S8 and NiS coated on the skeleton of Ni foam without any binder. The presence of wrinkle stripes on the surface of Co9S8/NiS composite provides abundant active sites. As expected, the Co9S8/NiS composite exhibits a high capacitance (2288 F g−1 and 2.52 F cm−2 at 1.0 A g−1). Furthermore, Co9S8-NiS/NF//N-rGO/NF HSCs device delivers a maximum specific energy of 47.41 Wh kg−1 at the specific power of 400 W kg−1. This work demonstrates the great potential of the Co9S8/NiS composite in supercapacitors and provides an effective reference scheme for the preparing the metal sulfide materials with enhanced charge storage performance.

Waste particleboards are largely generated from discarded furniture, floor, and other building materials, which can to be efficiently utilized as energy source by pyrolysis technologies. However, due to the existence of the adhesives and ash inside, waste particleboards are relatively hard to be pyrolyzed and form certain amounts of nitrogenous compounds. In order to improve the pyrolysis reactivity and tune the pyrolytic products, wood is proposed to be blended with waste particleboards for the co-pyrolysis treatment. In this study, the pyrolysis characteristics and chemical composition of pyrolytic vapors of samples with different blending ratios were studied using the TGA and Py-GC-MS analyses. The results showed as increasing the weight percentage of poplar wood, the pyrolysis activation energy and char residue content of the blends were gradually reduced, which was almost a linear correlation. Nevertheless, the chemical composition and distribution of pyrolytic vapors products of the samples was varied nonlinearly with blending ratio, and poplar wood exhibited a significant influence on the production of pyrolytic compounds from waste particleboards. The yields of most pyrolysis products reached the highest when the ratio of poplar wood was 50%, which probably indicated the existence of a synergy effect during the co-pyrolysis of different types of feedstock. It is believed that the results of this study are beneficial to the pyrolysis conversion of waste wood-based materials.

Low-dimensional magnetic materials with high stabilities and outstanding magnetic properties are essential for the next generation of spintronic devices. We will discuss the intrinsic magnetism in ...

Electrocatalytic oxygen evolution in acidic media is crucial for promoting water splitting. Herein, we report an Ag1/IrOx single atom catalyst (SAC) with Ag single atoms embedded in an IrO2 matrix ...

Two-dimensional vanadium carbide (V2C) and titanium carbide (Ti3C2) MXenes were first synthesized by exfoliating V2AlC or Ti3AlC2 and then introduced jointly into magnesium hydride (MgH2) to tailor the hydrogen desorption/absorption performances of MgH2. The as-prepared MgH2-V2C-Ti3C2 composites show much better hydrogen storage performances than pure MgH2. MgH2 with addition of 10 wt % of 2V2C/Ti3C2 initiates hydrogen desorption at around 180 °C; 5.1 wt % of hydrogen was desorbed within 60 min at 225 °C, while 5.8 wt % was desorbed within 2 min at 300 °C. Under 6 MPa H2, the dehydrided MgH2-2V2C/Ti3C2 can start to recover hydrogen at room temperature, and 5.1 wt % of H2 is obtained within 20 s at a constant temperature of 40 °C. The reversible capacity (6.3 wt %) does not decline for up to 10 cycles, which shows excellent cycling stability. The addition of 2V2C/Ti3C2 can remarkably lower the activation energy for the hydrogen desorption reaction of MgH2 by 37% and slightly reduce the hydrogen desorption reaction enthalpy by 2 kJ mol-1 H2. It was demonstrated that the combination of V2C and Ti3C2 promotes the hydrogen-releasing process of MgH2 compared with addition of only V2C or Ti3C2, while Ti3C2 impacts MgH2 more significantly than V2C in the hydrogen absorption process of MgH2 at ambient temperatures. A possible mechanism in the hydrogen release and uptake of the MgH2-V2C-Ti3C2 system was proposed as follows: hydrogen atoms or molecules may preferentially transfer through the MgH2/V2C/Ti3C2 triple-grain boundaries during the desorption process and through the Mg/Ti3C2 interfaces during the absorption process. Microstructure studies indicated that V2C and Ti3C2 mainly act as efficient catalysts for MgH2. This work provides an insight into the hydrogen storage behaviors and mechanisms of MgH2 boosted by a combination of two MXenes.

The Mg17Al12-BaO composite is synthesized via mechanical milling and the effect of BaO on the hydrogen sorption properties of Mg17Al12 is studied. Experimentally, we prepare the Mg17Al12-Ba, Mg17Al12-BaO, Mg17Al12-BaF2, and Mg17Al12-BaCl2 mixtures and find that the Mg17Al12-BaO composite shows a superior hydrogen storage performance. For instance, the hydrogenation (dehydrogenation) enthalpy of the Mg17Al12 decreases from 62.4 (91.2) to 58.6 (71.7) kJ mol-1 after adding BaO. When 1.0 wt % of H2 is absorbed/desorbed, the hydrogen absorption/desorption temperature of the Mg17Al12-BaO is 181/271 °C, which is 73/37 °C lower than that of the Mg17Al12. Furthermore, the catalytic mechanism of BaO on the hydrogenation of Mg17Al12 (110) surface is investigated by density functional theory (DFT). Calculations indicate that compared with the Mg17Al12 (110) surface, the adsorption energy and dissociation barrier of hydrogen on the Mg17Al12-BaO (110) surface are both improved significantly. Our experimental and theoretical results are helpful for understanding the effect of metal oxide on hydrogen storage properties of Mg17Al12.

The magnetorheological (MR) fluid damper, as a new generation of high-performance and intelligent vibration damping devices for engineering structures, has broad application prospects in structural vibration reduction. Nonlinear hysteresis is a complex phenomenon of MR dampers. In this paper, the phenomenological model is used to simulate the dynamics of MR dampers. To accurately and efficiently identify the parameters of the phenomenological model, the hierarchical enhanced particle swarm optimization (HEPSO) algorithm is proposed. This algorithm applies a hierarchical optimization mechanism and introduces media particles to the enhanced PSO (EPSO) algorithm to improve the optimization process of parameter identification and enhance the performance of the PSO algorithm without reducing the possibility of finding the optimal solution. Compared with the standard PSO (SPSO) algorithm and the EPSO algorithm, the HEPSO algorithm has a higher efficiency, accuracy and robustness in identifying a highly nonlinear hysteretic system problem.

This paper experimentally investigated the effect of low vent burst pressure on the overpressure buildup and flame evolution during the vented methane-air deflagrations in a 1 m3 rectangular vessel. CFD software FLACS was assessed in simulation of vented methane-air explosions against the experiment. Experimental results demonstrate that four overpressure peaks of Popen, Pout, Pext and Pacc from the vent failure, flame venting, external explosion and acoustically enhanced combustion, respectively, were observed except for the free venting case, in which only two overpressure peaks of Pout and Pext were monitored. The flame behaviors corresponding to different overpressure peaks were monitored especially at Pacc, where an abrupt increase in flame luminosity was observed on the bottom of the vessel due to the combustion of pockets of flammable mixture. Popen and Pacc increase with the vent burst pressure while Pout and Pext are nearly independent of the vent burst pressure. Double flame accelerations were observed owing to the vent rupture and flame venting. The phenomena of Helmholtz oscillation and the bulk motion of flame bubble always appeared after the vent rupture. The predicted overpressure agrees reasonably well with the experimental data. The discrepancy of the predicted and measured maximum peak overpressures reduces with increasing vent burst pressure. The predicted maximum peak overpressure and external flame length are slightly larger than those in experiment, which would facilitate the safe design in explosion venting and offer a better guidance in risk assessment. The simulation results also show that two overpressure peaks were recorded resulting from the pressure wave propagating above the vessel and the external explosion, respectively.

In this study, experiments on the vented deflagration of hydrogen–methane–air mixtures were performed in a vertical rectangular duct with a vent at its top end. A nondimensional vent coefficient ( K v ) was employed to characterize the effects of vent area ( A v ) on flame evolution and pressure buildup within and outside the duct. The maximum internal overpressure was attained near the duct bottom for a certain K v . As K v was increased from 2.2 to 11.9, the maximum internal overpressure near the vent and at the center of the duct increased monotonically; however, a nonmonotonic trend was observed at the duct bottom. Helmholtz oscillations of the internal flame and overpressure were observed in the tests for low K v , and acoustic oscillations of the internal overpressure with a frequency of ~1200 Hz appeared in all tests. The maximum external overpressure first increased and then decreased with an increase in K v . The external explosion induced a pressure peak in the duct, and the effect of external explosion on the venting of the internal deflagrations was weakened as K v ≥ 7.8.

The compression properties, wear resistance and electrical conductivities of TiCx/Cu composites fabricated via thermal explosion reaction combined with hot press in Cu–Ti-CNTs system at various nano-sized TiCx content with similar size were investigated. Results show that nano-sized TiCx can be effectively enhanced the Cu matrix. The σUCS, σ0.2 and wear resistance increased with the increasing content of TiCx particles. The ef and electrical conductivities decreased with increase of TiCx content. The ultimate compressive strength (σUCS), yield strength (σ0.2), Brinell Hardness and wear resistance increase with sacrificing the ef and the electrical conductivities. The 30 vol.% TiCx/Cu composites possess the highest σUCS, σ0.2, Brinell Hardness, wear resistance and the lowest ef, electrical conductivities among the 25–30 vol.% TiCx/Cu.

Aluminum hydride (AlH3) is a binary metal hydride that contains more than 10.1 wt% of hydrogen and possesses a high volumetric hydrogen density of 148 kg H2 m−3. Pristine AlH3 can readily release hydrogen at a moderate temperature below 200 °C. Such high hydrogen density and low desorption temperature make AlH3 one of most promising hydrogen storage media for mobile application. This review covers the research activity on the structures, synthesis, decomposition thermodynamics and kinetics, regeneration and application validation of AlH3 over the past decades. Finally, the future research directions of AlH3 as a hydrogen storage material will be revealed.

In this study, NaAlH4−based hydrogen storage materials with dopants were prepared by a two-steps in-situ ball milling method. The dopants adopted included Ce, few layer graphene (FLG), Ce + FLG, and CeH2.51. The hydrogen storage materials were studied by non-isothermal and isothermal hydrogen desorption measurements, X-ray diffractions analysis, cycling sorption tests, and morphology analysis. The hydrogen storage performance of the as-prepared NaAlH4 with Ce addition is much better than that with CeH2.51 addition. This is due to that the impact of Ce occurs from the body to the surface of the materials. The addition of FLG further enhances the impact of Ce on the hydrogen storage performance of the materials. The hydrogen storage capacity, hydrogen sorption kinetics, and cycle performance of NaAlH4 with Ce + FLG additions are all better than NaAlH4 materials with the addition of either Ce or FLG alone. The NaAlH4 with Ce and FLG addition starts to release hydrogen at 85 °C and achieves a capacity of 5.06 wt% after heated to 200 °C. The capacity maintains at 4.91 wt% (94.7% of the theoretical value) for up to 8 cycles. At 110 °C, the material can release isothermally a hydrogen capacity of 2.8 wt% within 2 h. The activation energies for the two hydrogen desorption steps of NaAlH4 with Ce and FLG addition are estimated to be 106.99 and 125.91 kJ mol−1 H2, respectively. The related mechanisms were studied with first-principle and experimental methods.

A novel design of a nearly perfect metamaterial absorber based on square split-ring resonators for terahertz sensing applications is proposed and analyzed. The design in this report is simulated and analyzed by using standard numerical simulation software. Magnetic and electric resonant field enhancement in the impedance matched absorber cavity enables stronger interaction with the dielectric analyte. The proposed structure is based on the simultaneous increase in the electromagnetic field and the surface current distribution at the resonance frequency. An absorptivity of 99% is achieved at 0.53 THz with a narrow resonance peak and a Q-factor of 44.17. At a fixed analyte thickness, the resonance frequency is sensitive to the refractive index of the surrounding medium. The influence of the thickness of the covering sample on the sensitivity and absorption coefficient of the absorber is comprehensively analyzed, and the reported design can be used as a refractive index sensor with a high sensitivity of 126.0 GHz/RIU and a figure of merit of 10.5 in the refractive index range from 1.0 to 2.0 at an analyte thickness of $15.0~\mu \text{m}$ . The results show that the sensor has high sensitivity to the analyte covering it. The sensor not only exhibits good sensitivity to thin analytes but also shows high sensitivity to analytes more than $10~\mu \text{m}$ thick in the terahertz low frequency band. Specifically, the sensitivity changes rapidly when the thickness of the sample changes in the range of 0- $6~\mu \text{m}$ , but slowly in the range of 6- $16~\mu \text{m}$ . In general, the response of the resonance frequency to changes in the refractive index of the sample becomes more sensitive as the thickness of the sample is increased from 0 to $16~\mu \text{m}$ . The reported terahertz sensor of a metamaterial absorber has potential applications in biomedical sensing and trace detection of substances.

To study the impact of rare earth oxide doping on the thermal failure of thermal barrier coatings, 0.5 mol%, 1.0 mol% and 1.5 mol% Nd2O3-doped YSZ coatings were prepared by explosive spraying. SEM, XRD, EDS and microhardness testing were used to analyse the effect of different rare earth oxide doping contents on the morphology, composition and mechanical properties of the coatings. With an increase in the Nd2O3 doping content, the porosity of the coatings was reduced. The decrease in the porosity increased the compactness of the coatings and improved the microhardness and fracture toughness. The bonding strength and thermal shock resistance of the coatings were the highest among the samples herein when the rare earth doping content was 1.0 mol%, and the values were 37.6 MPa and 200 times, respectively. The thermal shock failure mode of the coating was mainly due to the exfoliation of the inner layer of the ceramic layer. The luminous intensity of the coating increased with increasing rare earth oxide doping content, and the emission spectrum of the Nd2O3-modified YSZ coating after the thermal shock test produced a new emission peak at 594 nm, which decreased at 708 nm.

Effects of V and V-based compounds (VC, VO, VO2) on hydrogenation performances of the Mg17Al12 (110) surfaces are studied by first principles calculations. Results indicate that V and V-based compounds are stably adsorbed on the (110) surfaces. Additionally, the V-doped Mg17Al12 (110) systems are simulated. Calculations indicate that compared with the pure (110) system, H2 adsorption and dissociation on the Mg17Al12 (110) surfaces with adding V, VC, VO, and VO2 are dramatically promoted. Particularly, H2 are spontaneously dissociated on the vanadium oxide-adsorbed (110) surfaces. Analyses of density of states for the VO-adsorbed and VO2-adsorbed systems exhibit stronger hybridizations between V d sates and H s states, leading to the improvement of hydrogenation for the Mg17Al12 (110) surface. The vanadium oxide displays a preferred catalytic effect in our investigations, and the relative catalytic mechanism is revealed.

Background: The sustainable development of the building industry has drawn increasing attention around the world. Nanomaterials and nanotechnology play an important role in the processes of energy saving and reducing consumption in the building industry. Nanotechnology patents provide key technological support for the green development of the building industry. Based on patent data in China, this paper quantitatively analyzed the application of nanotechnology patents in the building industry and the time trend, regional differences, and evolution of China's nano-patent applications in the building field. Methods: In this study, the environmental total factor productivity of the building industry considering carbon constraints was determined and then used as the dependent variable to measure the green development of the building industry. On this basis, a panel data regression model was constructed to determine the impact of nano-patents on the green development of the building industry. Results: Nanotechnology patents in the building industry can significantly improve total factor productivity. From the perspective of patent composition, technology-based patents that focus on substantial innovation can significantly promote the green development of the building industry, whereas strategic patents show a significant inhibitory effect. Regionally, the western region of China has the advantage of being less developed and thus more efficient than the central and eastern regions in the application of new nano-products. Finally, the research also showed a significant lag in the application of China's nanotechnology patents and low implementation efficiency. Conclusion: Nano patents can promote green development in the building industry, but there is room for improvement in the speed with which laboratory inventions are transformed into building engineering applications.

In this study, experiments on the vented deflagration of stoichiometric hydrogen–methane–air mixtures were performed in a 300 mm (length) × 300 mm (width) × 1000 mm (height) duct with a 250 mm × 250 mm vent on the top surface, to investigate the effect of hydrogen fraction in fuel (χ) ranging from 0 to 1.0 on flame evolution and pressure buildup within and outside the duct. The results reveal that χ significantly affects flame propagation and pressure–time histories. The movement of the entire flame bubble toward and away from the vent and a spike-shaped structure, which had been observed in a vented methane–air mixture in a previous study, was observed for low χ in current tests. For a given χ, the maximum overpressure in the duct increased with the distance to the vent. Both the maximum internal and external overpressure increased slowly as χ increased from 0 to 0.7, and increased quickly with a further increase in χ. Violent external explosions occurred for χ = 0.8 and 1.0, and an extremely high internal overpressure appeared under the effect of the external explosion.

NiCo2O4/NiCoO2/graphene hybrid nanoarrays on Ni foam have been designed and synthesized through a hydrothermal method and post-annealing treatment. Highly conductive graphene sheets were embedded into or coated onto the NiCo2O4/NiCoO2 arrays, which strongly affect influence the morphology and electrochemical performance of hybrid nanoarrays. Under the effect of graphene, the architecture of the NiCo2O4/NiCoO2 consists of cluster-like arrays that are self-assembled from numerous nanoneedles and provides more electroactive sites for the redox reaction. However, without the assistance of graphene, the pure NiCo2O4/NiCoO2 exhibits the morphology of flake-like arrays on the Ni foam. The NiCo2O4/NiCoO2/graphene arrays show an ultrahigh capacity of 1439 C g-1 at a current density of 1 mA cm-2, which is far larger than that of the pure NiCo2O4/NiCoO2 flake-arrays (695 C g-1). Furthermore, even at a high current density of 60 mA cm-2, the NiCo2O4/NiCoO2/graphene arrays maintain a high gravimetric capacity of 1172 C g-1 (capacity retention: 81.4%), which indicates an excellent rate capability. Further, the hybrid capacitor shows a maximum energy density of 34.3 Wh kg-1. The present study suggests that the NiCo2O4/NiCoO2/graphene hybrid arrays have great application potential as a positive electrode for hybrid supercapacitors.

In situ TiCp was fabricated via combustion synthesis in an Al–Ti–C system. The quality of copper plating was easily observable on the surface of spherical in situ TiCp. A study was conducted to assess the influences of the stirring method, plating temperature and particle-to-solution ratio. According to the results, magnetic stirring is an advantageous stirring method. During the plating process, the plating quality reaches the maximum level at 303 K under magnetic stirring. Moreover, uniform and dense plating is achieved when the particle-to-solution ratio reaches 1 g/100 ml. The concentration of solution and ion activity can affect the speed at which Cu2+ is attached to the growing core, which plays a significant role in the quality of copper plating.

Human trajectory prediction is essential and promising in many related applications. This is challenging due to the uncertainty of human behaviors, which can be influenced not only by himself, but also by the surrounding environment. Recent works based on long-short term memory &#x0028 LSTM &#x0029 models have brought tremendous improvements on the task of trajectory prediction. However, most of them focus on the spatial influence of humans but ignore the temporal influence. In this paper, we propose a novel spatial-temporal attention &#x0028 ST-Attention &#x0029 model, which studies spatial and temporal affinities jointly. Specifically, we introduce an attention mechanism to extract temporal affinity, learning the importance for historical trajectory information at different time instants. To explore spatial affinity, a deep neural network is employed to measure different importance of the neighbors. Experimental results show that our method achieves competitive performance compared with state-of-the-art methods on publicly available datasets.

Commercial wrought Mg alloys normally contain low alloying contents to ensure good formability. In the present work, high-alloyed Mg-6Al-4Zn-xSn (x = 1, 2 and 3 wt.%, respectively) alloys were fabricated by extrusion. Hereinto, Sn was proven to play an effective contribution to simultaneous improvement in strength and ductility that are traditional trade-off features of synthetic materials. It was found that the average grain size of those alloys decreases significantly from ∼11 to ∼4 μm as a function of Sn contents increasing from 0 to 3 wt.%, while the amounts of Mg2Sn and Mg17Al12 particles continuously increase. More importantly, the addition of Sn leads to the transformation of dominated deformation modes from { 10 1 ¯ 2 } extension twinning (1 wt.%) to pyramidal slip (3 wt.%) during tensile tests along the extrusion direction at room temperature. The advantageous combination of ultimate tensile strength (∼366 MPa) and elongation (∼19 %) in Mg-6Al-4Zn-3Sn alloy is mainly attributed to the strong strain hardening ability induced by the enhanced activity of non-basal slip. This work could provide new opportunities for the development of high-alloyed wrought Mg alloys with promising mechanical properties.

In order to expand the application of polyimide resin matrix composites in the hot stage components of aeroengine, YSZ-based thermal protective composite coating was prepared on the surface of polyimide-based composites by detonation gun spraying. Sandblasting, sandpaper polishing and laser ablation were used to improve the surface roughness of the composites matrix. Bond bottom layer (Al, Cu, Zn), NiCoCrAl intermediate transition layer and YSZ top layer were matching with different thickness. The cross-section structure of the composite coating observed by SEM shows that the composite coatings of 0.1 mm Al bottom layer, 0.1 mm NiCoCrAl transition layer and 0.3 mm YSZ top layer are the best thickness matching for thermal protection of polyimide-based composite materials. There is no thermal damage to the surface and interior of the substrate during the preparation of the coating. The cross-section structure of the coating is uniform, and the interface between the layers is closely bonded and no micro-damage, Cracks and holes appear. After sandblasting, the bonding strength of the coating is 16.5 MPa by lattice laser texture treatment. The structure and thermal insulation properties of the composite coating are the best at 800 °C. The thermal conductivity is 1.46 W/(m·K), the specific heat capacity is 0.58 J/(g·K), and the thermal expansion coefficient is 7.89 × 10-6/K.

Heating rate is crucial to the pyrolysis process of charring materials in the thermal protection system (TPS) of spacecraft. In order to study the influence of heating rate on the thermal response of charring materials, a novel formula for pyrolysis rate of charring materials is presented on the basis of experimental results of charring materials under different heating rates and the Levenberg-Marquardt algorithm. Then combined with the pyrolysis layer model, from the numerical simulation we find an interesting result that the traditional method to determine pyrolysis rate without considering the heating rate is conservative for the design of TPS, but the novel method in this study contributes to optimization design of TPS in spacecraft.

Magnesium hydride (MgH2) is a candidate material for hydrogen storage. MgH2–AlH3 composite shows superior hydrogen desorption properties than pure MgH2. However, this composite still suffers from poor cycling performance. In this work, NbF5 was utilized to improve the cycling properties of the MgH2–AlH3 composite. Cycling hydrogen desorption studies show that NbF5 significantly improves the cycling stability of MgH2–AlH3. The MgH2–AlH3–NbF5 composite can release about 2.7 wt% of hydrogen at 300 °C for 1 h and the hydrogen desorption capacity can maintain at 2.7 wt% for more than 100 cycles. In comparison, the hydrogen desorption capacity of the MgH2–AlH3 composite is decreasing with the cycle number increasing. The capacity is reduced from a maximum value of 3.3 wt% to about 1.0 wt% after 40 cycles. Brunauer–Emmett–Teller (BET) surface area measurements show that the particle size of MgH2–AlH3 composite decreases after cycling, which means pulverization of the composite. NbF5 can to some extent suppress the pulverization of the composite during cycling, which partially contributes to the improvement of the cycling hydrogen desorption properties of the material. NbF5 addition significantly improves the cycling hydrogen desorption properties of the MgH2−AlH3 composite.

MgTM/ZIF-67 nanocomposites were prepared by the deposition-reduction method using ZIF-67, MgCl2, and TMClx (TM = Ni, Cu, Pd, Nb) as raw materials. The dehydrogenation activation energies of MgTM/ZIF-67 (TM = Ni, Cu, Pd, Nb) nanocomposites were calculated to be 115.4 kJ mol−1 H2, 115.7 kJ mol−1 H2, 113.6 kJ mol−1 H2, and 75.8 kJ mol−1 H2, respectively; hence, the MgNb/ZIF-67 nanocomposite manifested the best comprehensive hydrogen storage performance. The hydrogen storage capacity of the MgNb/ZIF-67 nanocomposite was hardly attenuated after the 100th hydrogen absorption-desorption cycle. The dehydrogenated enthalpies of MgH2 and CoMg2H5 in MgNb/ZIF-67 hydride were calculated to be 72.4 kJ mol−1 H2 and 81.0 kJ mol−1 H2, respectively, which were lower than those of additive-free MgH2 and Mg/ZIF-67. The improved hydrogen storage properties of MgNb/ZIF-67 can be ascribed to the CoMg2–Mg(Nb) core-shell structure and the catalytic effects of NbH and niobium oxide nanocrystals.

Biodegradable vascular stent is mainly made of materials that can be naturally decomposed. After implantation into human blood vessels, the vascular stent can be continuously degraded over time and eventually disappear completely after the treated blood vessels are healed and support from the vascular stent is not needed. The vascular stent materials used in clinic should have good biocompatibility, which mainly involves blood compatibility and cell compatibility. In terms of cell compatibility, the influence of materials on cell growth should be observed. The various biological materials should have good anticoagulant character, so as to reduce the tendency of thrombosis and avoid the occurrence of various risk events in clinical treatment.

Biodegradable vascular stent is mainly made of materials that can be naturally decomposed. Magnesium and its alloys have excellent mechanical properties and biocompatibility. The vascular stent made of magnesium and its alloys has the unique advantages of strength of metal scaffolds and bioabsorbability of degradable polymer scaffolds. Due to the special microenvironment inside the blood vessels, the stent should have good resistance against corrosion. After implantation of metal materials for human tissue repair, the surface oxidation film spontaneously formed in the air will react with the human physiological environment. The nature of the interface between materials and tissues will have a certain impact on the corrosion resistance of metals and the degree of metal ion release, thus determining the biocompatibility of materials.

In order to study the variation of rare earth oxides during thermal failure of thermal barrier coatings, Eu2O3-doped YSZ coatings with 0.5 mol%, 1.0 mol% and 1.5 mol% were prepared by explosive spraying. SEM, XRD, EDS and microhardness tester were used to analyze the effect of different rare earth oxide doping content on the morphology, composition and mechanical properties of the coatings. The results showed that with the increase of rare earth oxide doping content, the porosity of the coatings decreased, and the microhardness and fracture toughness increased. When the doping amount of rare earth oxide is 1.0 mol%, the bonding strength and thermal cycle times of the coating are the highest, 33.4 Mpa and 185 times respectively. With the increase of the doping amount of rare earth, the luminous intensity of the sprayed coating increases. After thermal shock test, the luminous intensity of Eu2O3-doped YSZ coatings at 592 and 608 nm decreased to a certain extent.

In order to improve the erosion resistance and toughness of thermal barrier coatings, YSZ coatings, 20 vol%-AlBOw whisker modified YSZ coatings and 20 vol%-BNw whisker modified YSZ coatings were prepared by plasma spraying. The cross-section structure, morphology, composition and phase composition of coatings and powders were analyzed by SEM, EDS and XRD. The erosion resistance of three coatings was tested by self-made erosion tester. The crack growth resistance of coatings was tested and calculated by Vickers hardness tester. The results show that the density of the coating is improved by adding AlBOw and BNw. The whisker inhibits the crack propagation through the mechanisms of crack deflection, whisker pull-out and whisker bridging. The addition of whisker improves the erosion resistance of YSZ coating by 8.17% and 13.94%, which can effectively improve the service life of thermal barrier coating.

Al-Mg-Si (AA6xxx) series alloys have been used widely in automotive industry for lightweight purpose. This work focuses on developing a short process for manufacturing Al-0.5Mg-1.3Si (wt.%) alloy sheets with good mechanical properties. Hereinto, a preparation route without homogenization was proposed on the basis of sub-rapid solidification (SRS) technique. The sample under SRS has fine microstructure and higher average partition coefficients of solute atoms, leading to weaker microsegregation owing to the higher cooling rate (160 °C/s) than conventional solidification (CS, 30 °C/s). Besides, Mg atoms tend to be trapped in Al matrix under SRS, inducing suppression of Mg2Si, and promoting generation of AlFeSi phase. After being solution heat treated (T4 state), samples following the SRS route have lower yield strength compared with that by CS route, indicating better formability in SRS sample. After undergoing pre-strain and artificial aging (T6 state), the SRS samples have comparable yield strength to CS samples, satisfying the service requirements. This work provides technological support to industrially manufacture high performance AA6xxx series alloys with competitive advantage by a novel, short and low-cost process, and open a door for the further development of twin-roll casting based on SRS technique in industries.

The exercise of quantifying the energy consumption data assembled through household surveys, either by the recall-based approach or the meter-based approach, remains a challenging task, especially in rural areas of developing countries. In this article, we propose a device-based bottom-up accounting method for estimating household energy consumption. This method provides microlevel disaggregated estimates at the intensive margin and documents other difficult-to-measure energy consumption such as biomass at the extensive margin. Even though measurement errors of the household survey might still exist, the structured questionnaire of daily routine behavior questions should greatly alleviate the problem. The new method supplements the existing household energy statistical system, improves its flexibility, and is particularly applicable in developing countries and/or rural areas. We apply the method to a Chinese rural household survey and discuss its differences and similarities with the conventional methods.

As a part of the energy transmission chain, gearboxes are considered as important components in rotating machines, and the gearbox failure results in costly economic losses. Therefore, it is necessary to detect the appearance of incipient gearbox faults by implementing an appropriate detected model. The incipient failure characteristics of the gearbox are weak and hidden in a set of time-varying series signals the vibration signals, which is difficult to effectively extract under the background of strong noise. The PCA method is not effective in detecting weak fault features in time-varying signals, so this paper proposes a method based on Deep Recursive Dynamic Principal Component Analysis (Deep RDPCA) to detect incipient faults in gearboxes. The proposed approach is modeled via both the deep decomposed theorems and time-varying dynamic model based on traditional PCA to extract characteristic of time-varying and weak fault information under the background of strong noise. The proposed method could get a better real-time reflection for changed system by introducing “Moving Window” technologies, so that the incipient fault of gearbox could be detected accurately, too. Finally, the effect of Deep RDPCA-based fault diagnosis is compared with the results of PCA, DPCA, RDPCA, Deep PCA, and Deep DPCA methods. It is concluded that the proposed method can effectively capture the time-varying relationship of process variables and accurately extract the weak fault characteristics in the vibration signal, which effectively improves the fault detection performance.

To enhance the fracture toughness and thermal shock resistance of the thermal barrier coatings (TBCs), detonation spraying has been used to prepare modified neodymium (Ⅲ) oxide (Nd2O3)-doped yttria-stabilized zirconia (YSZ) TBCs containing 20 vol% (D1 coating) and 30 vol% (D2 coating) of boron nitride whiskers (BNws). Analyses were performed using a scanning electron microscope (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and a microhardness tester to examine the manner in which the doping content of different rare earth oxides affected the coating morphology, composition, and mechanical properties. The results denoted that the porosity of the D2 coating was 47.9% higher than that of the D1 coating; the whisker content was 30 vol% in the former and 20 vol% in the latter. The increased porosity reduced the microhardness and bond strength of the coating. However, the fracture toughness (KIC) of the D2 coating was increased to 2.67 MPa·m1/2 because the whisker content was 8.5% higher than that in the D1 coating. The thermal cycling life of the D2 coating was 245 cycles, and its thermal shock resistance was 9.9% higher when compared with that of the D1 coating. A TBC with better overall performance was obtained when BNw reached 30 vol%.

Stacking different two-dimensional (2D) nanomaterials into composite structures opens an opportunity to fabricate electrodes combining the advantages of the individual nanomaterials. Here, different types of MXene nanosheets are combined to create flexible all-MXene hybrid films with high gravimetric capacitance and excellent rate performance for flexible supercapacitors. Ti3C2Tx nanosheets are introduced in between Nb2CTx layers, leading to a significantly increased interlayer spacing. The self-restacking of both types of MXene nanosheets is effectively impeded, accelerating the diffusion of electrolyte ions and enabling more accessible 2D nanochannels. The freestanding Ti3C2Tx/Nb2CTx films deliver a high gravimetric capacitance of 370 F g−1 at a scan rate of 2 mV s−1, good rate performance with 56.1% capacitance retention at 200 mV s−1 and a long cycle life. Furthermore, the energy density of the assembled all-solid-state symmetric supercapacitor can reach up to 5.5 mW h g−1 at a power density of 141.4 mW g−1. Serving as a stable power source unit, the all-solid-state supercapacitor was also integrated with a flex sensor to fabricate a self-powered device. The route to fabricate Ti3C2Tx/Nb2CTx hybrid films with enhanced electrochemical performance is also applicable for other MXenes, promoting the application of MXenes in flexible supercapacitors and integrated electronic devices.

Due to the instability of α type HMX at low concentrations, it belongs to the impurity crystal form. To ensure the functional effectiveness, operational reliability and management safety of HMX, it is necessary to quantify the low content of the unstable α-HMX crystal form in the composite explosive. In this study, low-concentration α-HMX is quantitatively analyzed in a mixture of α- and β-HMX. First, terahertz time-domain spectroscopy (THz-TDS) is used to obtain the absorption spectrum of the α/β-HMX element in the frequency range of 0.2–2.0 THz, and the characteristic frequency is selected. The absorption coefficient data in the frequency band of 0.7–1.3 THz are considered as the sample data for quantitative analysis. Finally, support vector machine (SVM) algorithm is used to establish a regression model, and principal component analysis (PCA) is employed for feature extraction. Grid search (GS), genetic algorithm (GA) and particle swarm optimization (PSO) are utilized for parameter optimization in support vector regression (SVR). These algorithms are combined to establish six regression models, and their effectiveness is assessed. The experimental results show that all the six methods can predict the content of α-HMX components with a small error and a high prediction accuracy. Compared to GA-SVR and PSO-SVR models, the PCA-GA-SVR and PCA-PSO-SVR models exhibit higher prediction accuracy and stability. The test set of the PCA-GA-SVR model reveals an average absolute error of 0.880%. It has the highest prediction accuracy, and the coefficient of determination (R2) reaches 0.9996. This indicates that PCA and SVR can be effectively used in the detection of low-concentration HMX components and can serve as a reliable basis for the quantitative analysis of other explosives.

Whether pyrolysis gases combustion has effect on surface ablation of charring material is a key issue in the optimization design of thermal protection system for hypersonic vehicles. The coupled method considering combustion of pyrolysis gases in shock layer is presented, realized in MATLAB and validated by comparison with the arcjet experiments. Relationship between surface ablation and mole fraction of oxygen, mass injection rate of pyrolysis gases and surface temperature of charring material under different Mach numbers are predicted by this coupled method. Numerical results indicate that the protective effect of pyrolysis gases combustion on surface ablation is more and more obvious with increase of Mach number. This study is helpful to the optimization of thermal protection system for hypersonic vehicles.

In this study, we have theoretically designed a micro-structured photoconductive antenna based on the combination of split-ring resonator (SRR) and dipole photoconductive antenna. Further, we have used numerical simulations to prove that the proposed antenna can enhance the terahertz radiation characteristics. According to the equivalent circuit model analysis, the terahertz radiation power and the resonance frequency of this antenna were found to be closely related with the structural parameters of the SRR. A numerical model was established to simulate the effect of the structural parameters of SRR on the terahertz radiation characteristics of the proposed antenna. The results indicated that an increase in the width and length of SRR caused an increase in the peak power intensity and a decrease in the resonance frequency. Moreover, as the gap width of SRR was increased, the peak power intensity was decreased and the resonance frequency was increased. Furthermore, the terahertz radiation power increased with increase in the gap width of antennas. Overall, we show that high-power terahertz radiation sources with specific frequency can be obtained by optimizing the structural parameters of SRR, and such sources are potentially useful in a variety of fields such as biomedicine, material analysis, and detection systems.

The reduced graphene oxide-supported copper (Cu@rGO) nanocomposite was introduced to improve the electrochemical properties of La0.7Mg0.3Ni2.8Co0.5 alloy electrodes. Experimental results show that adding Cu@rGO nanocomposite with mass fractions of x wt% (x = 0, 3, 6 and 9) to the alloy electrodes provides electrodes with maximum discharge capacities of 368.9 mAh/g (x = 0), 373.2 mAh/g (x = 3), 407.3 mAh/g (x = 6) and 398.6 mAh/g (x = 9), and high-rate dischargeabilities at a discharge current density of 1200 mA/g of 40.5% (x = 0), 64.0% (x = 3), 82.0% (x = 6) and 76.0% (x = 9). The addition of Cu@rGO nanocomposite also provides alloy electrodes with hydrogen diffusion coefficients of 3.7 × 10−10 cm2/s (x = 0), 4.1 × 10−10 cm2/s (x = 3), 4.2 × 10−10 cm2/s (x = 6) and 4.0 × 10−10 cm2/s (x = 9). Clearly, the addition of 6 wt%Cu@rGO nanocomposite not only increases the electrochemical capacity of La0.7Mg0.3Ni2.8Co0.5 alloy electrodes, but also improves their electrochemical kinetic properties.

Using a deposition-reduction method, Mg/MOF nanocomposites were prepared as composites of Mg and metal-organic framework materials (MOFs = ZIF-8, ZIF-67 and MOF-74). The addition of MOFs can enhance the hydrogen storage properties of Mg. For example, within 5000 s, 0.6 wt%, 1.2 wt%, 2.7 wt%, 3.7 wt% of hydrogen were released from Mg, Mg/MOF-74, Mg/ZIF-8, Mg/ZIF-67, respectively. Activation energy values of 198.9 kJ mol−1 H2, 161.7 kJ mol−1 H2, 192.1 kJ mol−1 H2 were determined for the Mg/ZIF-8, Mg/ZIF-67, Mg/MOF-74 hydrides, which are 6 kJ mol−1 H2, 43.2 kJ mol−1 H2, and 12.8 kJ mol−1 H2 lower than that of Mg hydride, respectively. Moreover, the cyclic stability characterizing Mg hydride was significantly improved when adding ZIF-67. The hydrogen storage capacity of the Mg/ZIF-67 nanocomposite remained unchanged, even after 100 cycles of hydrogenation/dehydrogenation. This excellent cyclic stability may have resulted from the core-shell structure of the Mg/ZIF-67 nanocomposite.

A series of Mg1-xNbx (x = 0.17–0.76) alloy films were prepared by means of magnetron co-sputtering in this work, on the purpose of obtaining better hydrogen storage materials with controllable component and structure. Mg(Nb) solid solution (Mg0.83Nb0.17 and Mg0.76Nb0.24 film), BCC-(Mg1-xNbx) structure (Mg0.70Nb0.30 and Mg0.60Nb0.40 film), and Nb(Mg) solid solution respectively (Mg0.38Nb0.62 and Mg0.24Nb0.76 film) formed in the MgxNb1-x alloy films with the increases of Nb contents. It only took 3 min for BCC-Mg0.60Nb0.40 to absorb 2.3 wt% hydrogen at 473 K and took only 30 min to desorb 1.2 wt% hydrogen at 523 K. Moreover, the BCC structure maintained after hydrogenation or dehydrogenation, which promised good cyclic stability. The hydrogen storage capacities of Mg1-xNbx alloy films were decreased with the increases of Nb contents. Mg0.83Nb0.17 can absorb most hydrogen of 3.8 wt% and Mg0.24Nb0.76 absorbs least hydrogen of 1.0 wt%. The Nb not only played a role of catalyst but also cooperated with Mg to build the BCC-(Mg,Nb) structure. The former provided intergranular path for the hydrogen atoms to diffuse faster; the latter provided more and larger lattice interstices for hydrogen atoms to diffuse in grain more easily.

In opinion dynamics, how to model the enduring fragmentation phenomenon (especially the bipartite cleavage) of social opinions has long been a central problem. It is widely known that the confidence-based opinion dynamics provide an acceptable mechanism to produce fragmentation. In this study, taking the famous confidence-based Hegselmann–Krause (HK) model, we examine the robustness of the fragmentation coming from HK dynamics and its variations with prejudiced and stubborn agents against random noise. Prior to possible insightful explanations, the theoretical results in this paper explicitly reveal that the fragmentation of HK dynamics and its homogeneous variations finally vanishes in the presence of arbitrarily tiny noise, while only the HK model with heterogenous prejudices displays a solid cleavage in noisy environment. Moreover, it is found that noise could help regularize the group to form the innate bipartite cleavage.

Herein, we design and prepare Ni3S2/NiCo2O4 arrays on Ni foam with core-shell flakes structure as charge-storage materials. In this synthetic strategy, NiCo2O4 flakes are firstly grown on Ni foam substrate through simple hydrothermal process, and then ultrathin Ni3S2 nanoflakes are electrodeposited into scaffold of NiCo2O4 arrays. Those nanoflakes supported with each other can form a three-dimensional porous and interconnected structure, which afford more active sites and ion transfer channels for redox reaction. As expected, Ni3S2/NiCo2O4 arrays show excellent charge-storage properties in electrochemical energy storage, including high specific capacity of 1201 C g−1 (3.46 C cm−2) at 1 mA cm−2, which far larger than those of pure NiCo2O4(572 C g−1, 0.86 C cm−2) and Ni3S2 (612 C g−1, 0.98 C cm−2). Meanwhile, Ni3S2/NiCo2O4 arrays show a good rate capability of 742 C g−1 at 60 mA cm−2. Furthermore, hybrid device is fabricated using Ni3S2/NiCo2O4 arrays (positive electrode) and graphene on Ni foam (negative electrode). This device can deliver high energy density of 47.62 Wh kg−1, indicating a good application ability of Ni3S2/NiCo2O4 arrays. The excellent charge-storage performance of Ni3S2/NiCo2O4 arrays is attributed to the core-shell structure of flakes arrays and synergistic effects of two components.

To enhance the electrochemical property of a La0.7Mg0.3(Ni0.9Co0.1)3.5 alloy, a three-dimensional (3D) reduced graphene oxide (rGO)-supported nickel and nitrogen co-doped (Ni–N@rGO) nanocomposite is fabricated by an impregnation method and introduced into the La0.7Mg0.3(Ni0.9Co0.1)3.5 alloy. The results show that the reversible hydrogen storage property and the comprehensive electrochemical performance of the La0.7Mg0.3(Ni0.9Co0.1)3.5 alloy are enhanced effectively when it is modified by the Ni–N@rGO nanocomposite. The high-rate dischargeability values at a discharge current density of 1500 mA g−1 for the La0.7Mg0.3(Ni0.9Co0.1)3.5 alloy and Ni–N@rGO-modified samples are 0.0% and 70.5%, respectively. Additionally, the anodic peak currents for the unmodified alloy electrode is 892 mA g−1. Under the catalytic action of the Ni–N@rGO nanocomposite, the value increases to 2307 mA g−1, which is 2.59 times larger than that of unmodified samples. The results also indicate that the diffusion ability of the hydrogen atom in the alloy electrode body enhances significantly when modified by the Ni–N@rGO nanocomposite. The hydrogen diffusion coefficient for the La0.7Mg0.3(Ni0.9Co0.1)3.5 alloy electrode increases from 3.93 × 10−10 cm2 s−1 to 6.15 × 10−10 cm2 s−1 when is modified by Ni–N@rGO nanocomposite. These improvements in the comprehensive electrochemical properties are mainly attributed to the excellent electrochemical activity and conductivity of the Ni–N@rGO nanocomposite.

Lignin peroxidase (LiP) was obtained from Pichia methanolica through heterologous expression. LiP was extracted, purified, and immobilized on Fe3O4@SiO2@polydopamine (PDA) nanoparticles to acquire immobilized LiP. The optimal preparation conditions for immobilized LiP were investigated. Results showed that the immobilization efficiency of immobilized LiP reached 56.37% when the enzyme amount, PDA concentration, and immobilization time were 12 mg, 1.6 mg/mL, and 12 h, respectively. Compared with free LiP, the immobilized LiP showed good thermal stability and storage stability and improved pH tolerance. It also retained more than 30% of its initial activity after 8 cycles, demonstrating its improved reusability. The immobilized LiP demonstrated efficacy of reaction of 100%, 100%, 100%, 100%, 79%, 73%, and 65% for tetracycline, dibutyl phthalate, 5-chlorophenol, phenol, phenanthrene, fluoranthene, and benzo(a)pyrene, respectively, while the inactivated immobilized LiP only adsorbed

Experiments were conducted in an obstructed 3-m-long duct to investigate the effects of equivalence ratio, thickness of rupture membrane, and vent area on vented hydrogen–air deflagrations. Shockwave-induced pressure peaks were observed inside and outside the duct in some tests. In the tests with one end of the duct totally opened, the location at which the overall maximum internal overpressure is achieved depends on the thickness of the rupture membrane for a given equivalence ratio; however, it is independent of equivalence ratio for a given thickness of rupture membrane. The pressure peak resulting from an external explosion always dominates the pressure–time histories 1.5 m downstream of the duct exit. The maximum internal and external overpressures first increase and then decrease as the equivalence ratio increases from 0.26 to 3.57, unexpectedly; none of these increase monotonically with an increase in the thickness of the rupture membrane. Two explosion venting regimes, namely sonic and subsonic, are observed. During sonic venting, the maximum internal overpressure increases exponentially with a decrease in vent area; it is nearly independent of the vent area during subsonic venting when the vent area is larger than approximately 19% of the cross-sectional area of the duct.

In this paper, the effects of size, morphology and distribution of eutectic silicon on the thermal conductivity of Al-8Si alloy modified by Sr (0.04, 0.08, 0.12 wt.%) and Sb (0.1, 0.3, 0.5 wt.%) elements with T6 heat treatment were investigated. The results show that the modified fibrous eutectic silicon has a significant capability of improvement of thermal conductivity, while the amount of the modifier has a relatively weak effect on thermal conductivity. After T6 treatment, the fracture or spheroidization of the flake eutectic silicon and the disappearance of clustering phenomenon could raise thermal conductivity, but the coarsening of fibrous eutectic silicon is inconducive to thermal conductivity. Finally, the effect of eutectic silicon on electron transport is analyzed in detail, which could provide a reference for enhancing the thermal (or electrical) conductivity of hypoeutectic Al-Si alloy through effective microstructure control.