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Oblique detonation wave (ODW) has been investigated widely for application in ramjet-type engines, but there are less works concerning its instability in a confined space. Recently, a wave complex induced by ODW decoupling has been observed, and this study investigates the instability of this wave complex featuring a recirculation zone. Numerical results show that the wave complex with recirculation zone oscillates, but the oscillations are found to be periodic rather than random, never reported before. The dependence of the period and frequency on the corner location and angle are analyzed in detail, with very irregular motion tracks of recirculation zone cores. Further quantitative analysis by Fast Fourier transformation reveals two origins of instability: one is the basic oscillation of the recirculation zone associated with the movement of surrounding wave complex; the other is self-excitation inside the recirculation zone, which makes its motion tracks more complicated than the external wave configuration. [ABSTRACT FROM AUTHOR]

The dynamics of frontal and transverse shocks in gaseous detonation waves is a complex phenomenon bringing many difficulties to both numerical and experimental research. Advanced laser-optical visualization of detonation structure may provide certain information of its reactive front, but the corresponding lead shock needs to be reconstructed building the complete flow field. Using the multi-layer perceptron (MLP) approach, we propose a shock front reconstruction method which can predict evolution of the lead shock wavefront from the state of the reactive front. The method is verified through the numerical results of one- and two-dimensional unstable detonations based on the reactive Euler equations with a one-step irreversible chemical reaction model. Results show that the accuracy of the proposed method depends on the activation energy of the reactive mixture, which influences prominently the cellular detonation instability and hence, the distortion of the lead shock surface. To select the input variables for training and evaluate their influence on the effectiveness of the proposed method, five groups, one with six variables, and the other with four variables, are tested and analyzed in the MLP model. The trained MLP is tested in the cases with different activation energies, demonstrates the inspiring generalization capability. This paper offers a universal framework for predicting detonation frontal evolution and provides a novel way to interpret numerical and experimental results of detonation waves. [ABSTRACT FROM AUTHOR]

Initiation of an oblique detonation wave (ODW) results in a near-field region of curved detonation wave surface, which cannot be predicted by the detonation polar theory and lacks in-depth work on its features. In this study, Euler equations coupled with a two-step kinetic model are used to simulate ODW dynamics, and then the flow structures are analyzed by examining the asymptotic decay of local surface angle. The flow/reaction coupling is quantified by a non-dimensional Damköhler number Das that is defined as the ratio of the characteristic flow and chemical reaction length along streamlines. The results demonstrate a spectrum of local strong solutions forms, which always happens when the ODW transition pattern is abrupt, but the strong solutions deviate from the isolated strong solution predicted by the polar theory. Furthermore, the abrupt transition leads to a strong peak of Das, while the smooth one leads to a bump. Various simulated cases indicate that the transition pattern becomes abrupt and the local strong solution arises when the maximum Das reaches a critical range. [ABSTRACT FROM AUTHOR]

Two-dimensional numerical simulations are performed to investigate the effects of spatially discrete slot injection of reactants on the features of detonation wavelets in a rotating detonation engine (RDE). The detonation dynamics is described by a model based on the reactive Euler equations coupled with two-step, induction-reaction kinetics. By varying injection conditions and the chemical sensitivity of the reactive mixture, a parametric study is carried out to examine the influence of the injection-slot area ratio α on the detonation wavelet patterns and different flow features inside an RDE combustion chamber. The simulation results demonstrate that the injection conditions, i.e., stagnation temperature and pressure, have a similar influence on slot-ozzle rotating detonation wavelets (RDWs) as compared with the mini-nozzle RDWs reported in a previous study. The corresponding mass flow rate and inhomogeneity generated due to the presence of slot injection, however, play a key factor in the self-sustained rotating detonation and its frontal structure. • The detonation wavelets with slot injections are resolved computationally with GPU. • Flow features are compared between the slot injection and micro-nozzle injection. • The wavelet number dependence on slot injection stagnation properties are studied. • The instabilities induced by the slot injections in rotating detonation are highlighted. [ABSTRACT FROM AUTHOR]

Oblique detonation waves (ODWs) have potential applications in hypersonic propulsion, but the boundary of steady ODWs has not yet been examined comprehensively. In this study, Euler equations coupled with detailed chemical reaction models are used to simulate ODWs in hydrogen-air mixtures with relatively low flight Mach numbers (from 7 to 8) and different flight altitudes (30 km and 25 km). Decreases in the flight Mach number and altitude are shown to result in unsteady ODWs in a stoichiometric hydrogen-air mixture. These ODWs can be re-stabilized by decreasing the fuel‒air equivalence ratio. Regardless of different parameters of Mach number and altitude, unsteady ODWs appear only when the velocity in the induction zone exceeds that of the corresponding Chapman-Jouguet detonation. A low equivalence ratio also induces a long initiation length, limiting the availability of decreases in the equivalence ratio to maintain a steady ODW in practical applications. A flow‒combustion criterion is proposed for the application of ODWs, based on the steadiness of ODWs and fast initiation. Image 1 • Oblique detonations near the low flight speed/altitude boundary have been studied. • Unsteady waves can be re-stabilized by decreasing the fuel‒air equivalence ratio. • A Mach number analysis at the steady boundary clarifies the stabilization mechanism. • A flow‒combustion criterion is proposed for the application of shcramjet engines. [ABSTRACT FROM AUTHOR]

Liquid fuels have been widely used in propulsion systems for their higher energy density and easier storage, but there are few studies on oblique detonation engines (ODEs) using the liquid fuels. In this study, oblique detonation waves (ODWs) in partially pre-vaporized n –heptane sprays are simulated, using a hybrid Eulerian–Lagrangian algorithm with a skeletal chemical mechanism, to facilitate liquid fuels applications in ODE. A novel phenomenon has been observed, illustrating that the ODW initiation lengths in pre-vaporized n –heptane sprays firstly increase and then decrease with increasing fuel droplet diameters. It is found out that an increase of droplet diameter can increase the transferred heat amount caused by droplets evaporation and lower the inflow temperature, so leading to the increase of ODW initiation length firstly. However, extremely large droplet diameter can markedly reduce the heat transfer rate of the droplet and its surrounding mixture, and the compressed gas-stream behind oblique shock wave has a higher temperature that accelerate the induction chemical reaction and results in a decrease in the ODW initiation length. Furthermore, the unsteady oscillations of ODW initiation structures are also observed even for a steady inflow, which involves the periodic hot spots, normal detonation waves and their evolutions. Some factors causing the unsteady behavior of ODWs are tested through a sensitivity analysis method of the initiation lengths. Through the analyzation, the fluctuation of the post-shock temperatures is the main factor causing the fluctuation of initiation lengths, revealing that inhomogeneous heat loss by evaporation of dispersed liquid droplets is the main reason causing the unsteady behaviors of ODWs and the competition between heat release by chemical reactions and heat loss by evaporation determines the steadiness of ODWs. [ABSTRACT FROM AUTHOR]

The wavelet features of rotating detonation waves (RDWs) are numerically investigated using Euler equations and a two-step induction-reaction model. The effects of the inflow stagnation temperature T st and the heat release rate k R on the number, height and intensity of the RDWs are discussed in this study. An increase in the stagnation temperature results in more detonation waves in a combustion chamber, which indicates the number of RDWs is sensitivity to the thermodynamic state of the reactants. As the heat release rate decreases, the number of detonation wave decreases and an unstable wavelet pattern is observed. This is represented as the oscillation in height and intensity of the detonation. In addition, some numerical cases are performed to determine the effects of ignition patterns on the number of RDWs. The features of the flow fields are analyzed using varied inflow stagnation temperature and initiation patterns, identifying the co-existence of different wavelet configurations. • An increase in the stagnation temperature generates more rotating detonations. • The variation of heat release rate also changes the wavelet number. • The height and pressure of the detonation front oscillates periodically. • The wavelet features in rotating detonation is sensitive to the ignition patterns. [ABSTRACT FROM AUTHOR]

Two combustible mixtures, H 2 -O 2 -Ar and H 2 -O 2 -N 2 , are widely used in detonation research, but only the latter has been employed in oblique detonation wave (ODW) studies. In this study, ODWs in H 2 -O 2 -Ar are simulated to investigate their structural characteristics using reactive Euler equations with a detailed chemistry model. Similar to ODWs in H 2 -O 2 -N 2 mixtures, two observed structures are dependent on incident Mach numbers. However, in mixtures of 2H 2 + O 2 + 7Ar, the structures are sensitive to inflow static pressure P 0 , different from the structures in H 2 -O 2 -N 2 mixtures. Based on flow field analysis, the ratio of induction and heat release zone lengths R L is proposed to model the difference induced by dilution gas. Generally, R L is large in N 2 diluted mixtures but small in Ar diluted mixtures. Low R L indicates that induction is comparable with the heat release zone and easily changed, resulting in pressure-sensitive structures. When the dilution gas changes gradually from N 2 to Ar, the ratio R L increases slowly at first and then declines rapidly to approach a constant. The variation rule of R L is analyzed and compared with results from calculations of a constant volume explosion, demonstrating how different dilution gases influence ODW structures. [ABSTRACT FROM AUTHOR]

Oblique detonations induced by two-dimensional, semi-infinite wedges are simulated by solving numerically the reactive Euler equations with a two-step induction-reaction kinetic model. Previous results obtained with other models have demonstrated that for the low inflow Mach number M 0 regime past a critical value, the wave in the shocked gas changes from an oblique reactive wave front into a secondary oblique detonation wave (ODW). The present numerical results not only confirm the existence of such critical phenomenon, but also indicate that the structural shift is induced by the variation of the main ODW front which becomes sensitive to M 0 near a critical value. Below the critical M 0 ,cr , oscillations of the initiation structure are observed and become severe with further decrease of M 0 . For low M 0 cases, the non-decaying oscillation of the initiation structure exists after a sufficiently long-time computation, suggesting the quasi-steady balance of initiation wave systems. By varying the heat release rate controlled by k R , the pre-exponential factor of the second reaction step, the morphology of initiation structures does not vary for M 0  = 10 cases but varies for M 0  = 9 cases, demonstrating that the effects of heat release rate become more prominent when M 0 decreases. The instability parameter χ is introduced to quantify the numerical results. Although χ cannot reveal the detailed mechanism of the structural shift, a linear relation between χ and k R exists at the critical condition, providing an empirical criterion to predict the structural variation of the initiation structure. [ABSTRACT FROM AUTHOR]

In this study, numerical simulations using the inviscid Euler equations with one-step Arrhenius chemistry model are carried out to investigate the effects of activation energy and wedge angle on the stability of oblique detonation surfaces. Two kinds of cellular structure are studied, one is featured by a single group of transverse waves traveling upstream, referred to as LRTW (left-running transverse waves), and the other is featured by additional RRTW (right-running transverse waves). The present computational simulation reveals the formation of un-reacted gas pockets behind the cellular oblique detonation. Numerical smoked foil records are produced to show the emergence of the two types of transverse waves and the evolution of the unstable cellular structure of the oblique detonation. The transverse wave dynamics, including the colliding, emerging and splitting types, are found to be similar to the normal detonation propagation, demonstrating the instability mechanism is originated from the inherent instability of cellular detonations. Statistical analysis on the cellular structure is carried out to observe quantitatively the influences of activation energy and wedge angle. Results from the parametric study show that high activation energy and low wedge angle are favorable to the LRTW formation. However, the condition for the RRTW formation is more complex. In the case of low activation energy, small wedge angle is beneficial to the RRTW formation, as to the LRTW formation. In contrary, for high activation energy, there appears one moderate wedge angle favoring the RRTW formation and giving the shortest length between the onset of both LR and RR transverse waves. For quantitative comparison, we analyze the variation of two distances with the wedge angle, one is between the detonation initiation and LRTW formation points, and the other between LRTW and RRTW formation points. Results show the latter is relatively less pronounced than the former, indicating the RRTW formation depends mainly on the activation energy and the generation of LRTW. [ABSTRACT FROM AUTHOR]

Sodium dodecyl sulfate stable nanoscale zero-valent iron (SDS-nZVI) was synthesized by the sodium borohydride reduction method, characterized with SEM and XRD. SDS-nZVI was used for the removal of Cr (VI) from aqueous solutions at different conditions in a batch process. XRD analysis indicated the presence of iron oxide and iron-chromium hydroxide coprecipitation on the surface of SDS-nZVI after reaction some time. The reaction kinetics, mechanism, isotherms, and thermodynamics for Cr (VI) removal of aqueous solution via SDS-nZVI were investigated. The pseudo-second-order model was relatively suitable for describing the reaction process. Intraparticle diffusion model was used to analysis the mechanism, the results indicated that there were two processes (bulk diffusion and surface diffusion) controlling the reaction rate, while only one was rate limiting in any particular time range. The fitted Temkin and D-R model satisfactorily explanted the experimental data in the range of 303–343 K. The maximum removal capacity of SDS-nZVI for Cr (VI) was obtained for 336.7 mg g−1at 303 K. The overall removal process was endothermic. These results demonstrated that SDS-nZVI could potentially be used as an effective material for environmental remediation. [ABSTRACT FROM PUBLISHER]

Abstract: Aluminum (Al) particle–air detonation is very complicated because it includes multi-phase combustion phenomenon. Thus numerical simulations are often over-simplified. Here, the detonation is simulated by solving one-dimensional equations with more realistic heat capacities that vary with the dust mixture temperature. The effect on detonation parameters from the realistic heat capacities for the solid particles is investigated with a hybrid combustion model. The calculated results indicate that the detonation pressure, temperature and velocity vary significantly with changes in the heat capacity. Except for the velocity, these parameters are overestimated in numerical simulations when a constant heat capacity of the pre-shock mixtures is used. Furthermore, the realistic heat capacities have a strong effect on small diameter particles, but a weak effect on large diameter particles. Thus, when constant heat capacities are used, the combustion characteristic lengths are a function of the particle diameters with a power dependence of 1.77, whereas the power dependence decreases to 1.49 when realistic heat capacities are used. Moreover, if realistic heat capacities are applied, an “abnormal” strong detonation wave may appear in a dust mixture having large diameter particles. This phenomenon is consistent with the current combustion model, but it indicates that the value of heat released should also vary with the gas temperature in a fashion similar to that of the heat capacities. [Copyright &y& Elsevier]

Two-dimensional rotating detonation waves (RDWs) with separate injections of hydrogen and air are simulated using the Navier–Stokes equations together with a detailed chemical mechanism. The effects of injection stagnation temperature and slot width on the detonation propagation patterns are investigated. Results find that extremely high temperatures can lead to a chaotic mode in which detonation waves are generated and extinguished randomly. Increasing the slot width can reduce the number of detonation waves and finally trigger detonation quenching at a low injection stagnation temperature. But increasing the slot width can change the RDW propagation pattern from a chaotic to a stable mode under high injection temperature. Furthermore, the kinetic parameter τ (representing the chemical reactivity of the mixture) and the kinematic parameter α (representing the mixing efficiency of hydrogen and oxygen) are introduced to distinguish the RDW propagation patterns. [Display omitted] • The effect of injection on rotating detonation waves is quantitatively displayed. • Increasing slot width can lead to the detonation propagation patterns stably. • Increasing injection stagnation temperature may lead to a chaotic mode. • Two parameters are proposed to distinguish the detonation propagation patterns. [ABSTRACT FROM AUTHOR]

The oblique detonation waves have been studied extensively, but the wave characteristics influenced by the geometrical restriction have not been fully addressed. In this study, we examine the wave stability and the thrust performance in a contraction-expansion channel with varying velocity. A supersonic stoichiometric inflow of hydrogen-oxygen inflow is established in the computational domain, and the compressible reactive Navier-Stokes equations are solved using a comprehensive chemical model. As the velocity increases, the detonation wave inside the channel exhibits two successive unsteady states: the half normal detonation wave (half NDW) and the re-ignition oblique detonation wave (re-ignition ODW). In the half NDW state, the upper part of the wave surface is a basically stable NDW, while the lower part oscillates regularly as the reaction front. In the re-ignition ODW state, the explosion of the reaction front and the retreat of the detonation surface occur in proper order. Furthermore, the thrust associated with these newly discovered oscillation wave systems exhibits unstable behavior, with an important observation that it does not consistently decrease with increasing velocity. Notably, there is a significant increase in thrust during the transition from the half NDW state to the ODW state, as well as when the position of the oblique detonation wave shifts downstream. [Display omitted] • The oblique detonation wave structure and thrust performance in a contraction–expansion channel are revealed. • With increasing velocity, thermal choking unstarting, half normal detonation, and oblique detonation states emerge. • Two unsteady wave states were identified for the first time, and the primary flow characteristics were discerned. • Throughout the entire super-detonation process, the effect of V in / V cj on thrust is non-monotonic decreasing. [ABSTRACT FROM AUTHOR]

During lunar landings, impact craters and other complex terrains may intensify dust dispersion produced by plume-surface interaction, posing disturbances and threats to lunar modules. This study investigates the interaction between rocket plume of the Chang’E-5 module and a module-scale crater using the direct simulation Monte Carlo method. The results show that a steep crater significantly changes near-field flow structures, leading to the formation of a large recirculation bubble beneath the nozzle. The recirculation bubble increases regolith erosion on the crater wall and entrains dust particles into the nozzle, which can cause severe damage to the engine and other devices. Meanwhile, as the crater steepens, the deflection angle of the gas flow significantly increases, elevating pressure and heat flux on the module surface. The maximum inclination angle of lunar dust also increases, seriously blocking the landing visibility. For less steep craters, although the plume deflection and dust dispersion are less severe, the total erosion flux is higher according to Roberts erosion model, implying more damage to the module. This study reveals the significant effects of a module-scale crater on the lunar plume-surface interaction and can serve as a reference to predict and mitigate threats of extreme terrains to lunar missions. [ABSTRACT FROM AUTHOR]

Emissions of nickel (Ni) are harmful to the environment and people's health. Although nano zero‐valent iron (nZVI) has a lot of potential for treating water pollution, its instability and tendency for aggregation have limited its application. In order to improve its properties, composite adsorbent MCM‐41/rGO supported nZVI (nZVI/MCM‐41/rGO) is designed for improving the properties of nZVI, and it is characterized by SEM, XRD, FTIR and BET. The results show that it has an apparent Fe(0) crystallinity and modest rGO crystallinity, as well as a rough and porous structure. There are many oxygen‐containing groups found on the surface of nZVI/MCM‐41/rGO, such as −OH, −COOH, and Si−O. The pore diameter is concentrated at 23.82 nm, and the specific surface area is 15.94 cm2/g. The consequences of several parameters such as contact time, initial metal ion concentration, adsorbent dosage, and pH for adsorption efficiency were investigated. The best performance is occurred at pH 6, C0=80 mg/L with a 2 g/L adsorbent dosage, and after 180 min, a maximum adsorption capacity of 41.82 mg/g is reached at 333 K. The Dubinin‐Radushkevich isotherm and second order kinetic models fit the Ni(II) adsorption process well. It is determined through analysis of the thermodynamic parameters that the adsorption progress is endothermic (ΔH0>0) and spontaneous (ΔG0<0). nZVI/MCM‐41/rGO has proven to be an effective and alternative material for the removal of Ni(II) ions from aqueous media due to its excellent removal ability, availability, and low cost. [ABSTRACT FROM AUTHOR]

The rapid recombination of photogenerated charge carriers seriously impedes the photocatalytic activity of BiVO4. We propose an effective strategy to overcome this by constructing heterostructured BiVO4-{010}/Ag plasmonic photocatalysts by the multi-object synchronous optimization of the microstructure of the BiVO4 matrix including the optimization of the active facets, morphology, and surface defects. A solvothermal method was employed to realize the optimization of BiVO4. The influence of BiVO4 with different microstructures on the construction and photocatalytic performance of BiVO4/Ag were studied. In terms of construction, the degree of exposure of the {010} facet of BiVO4 is a key factor in the thermodynamic process determining the formation of the {010} facet–Ag heterojunction, whereas the degree of exposure of the active facets, morphology, and surface defects of BiVO4 are crucial factors in the dynamic processes. The pseudo-first-order kinetic constant (k) of the photocatalytic degradation of Rhodamine B (RhB) for FS-BVO {010} under visible light irradiation is 8.8 and 4.8 times that of SS-BVO {010} and SS-BVO, respectively, and 2.8 and 3.8 times that of SS-BVO {010}/Ag and SS-BVO/Ag, respectively. FS-BVO {010} exhibited the second highest photocatalytic performance, primarily attributed to the promotion of the separation and migration of the photogenerated charge, the increased lifetime of the charge carriers, and more active sites. This depended on the multi-object synchronous optimization of the microstructure, including the preferentially exposed {010} facet, the four-star-like morphology with a stair-stepping hierarchical structure, and the {010} facet defect structure. This suggests that the photocatalytic performance of BiVO4 can be improved further by optimizing the microstructure of the BiVO4 matrix than by constructing BiVO4/Ag based on conventional BiVO4. Furthermore, the k value for FS-BVO {010}/Ag is 4.2 times that of FS-BVO {010}. This enhanced photocatalytic performance may be mainly due to the synergistic effect between the optimized microstructure and the {010} facet–Ag Schottky junction, and the surface plasmon resonance effect of the Ag nanoparticles, which can further extend the absorption of light, suppress the recombination of the photogenerated charge, and prolong the lifetime of the charge carriers. ˙O2− and h+ are the dominant active species in the photodegradation of RhB over FS-BVO {010}/Ag and a possible photocatalytic mechanism is proposed. This work provides new insights into constructing efficient photocatalysts based on matched surfaces/interfaces by optimizing the microstructure of a pure semiconductor for utilization in the field of environmental treatment. [ABSTRACT FROM AUTHOR]

The surface instability of oblique detonation waves (ODWs) without perturbations has been extensively investigated, yet the impact of external perturbations remains under-explored. Utilizing reactive Euler equations coupled with a two-step induction-exothermic reaction model, this study conducts a numerical examination of the evolution of unstable ODW surfaces subjected to a continuous sinusoidal density/temperature perturbation inflow. The results show that, without inflow perturbations, the ODW can evolve into triple points in the downstream due to detonation instability, similar to previous work. However, a small continuous perturbation can induce a significant forward movement of the ODW unstable position. Surprisingly, as the perturbation magnitude increases, the changes in the unstable position become progressively less pronounced. By increasing the perturbation frequency, the oscillation amplitude first increases, but a decreasing period/stage occurs with a modest frequency. To investigate the response of ODW to the increase in perturbation, the frequency characteristics and numerical smoked cells of detonation surfaces are examined and analyzed using Fast Fourier Transformation. The power spectral density indicates the presence of two distinct oscillation modes within oblique detonation. Low-frequency, small-amplitude perturbations serve to amplify the instability of the detonation, and more irregular oscillations could be observed. Conversely, high-frequency, large-amplitude perturbations suppress the development of small-scale waves on the detonation wavefront and lead to a relative regular oscillation, indicating that the wavefront pressure oscillations are entirely determined by inflow perturbations and become predictable. These findings have significant implications for the control of intrinsically unstable ODWs, providing valuable insights into the regulation of ODW dynamics. [ABSTRACT FROM AUTHOR]

During a lunar module landing, the gas extended from the engine nozzle impinges on the lunar surface. A recirculation bubble could form beneath the surface shock wave, which alters the flow pattern close to the surface, thus affecting the surface soil transportation process. This study conducted numerical simulations to investigate the flow characteristics, formation mechanism, and effects of this recirculation bubble on surface soil erosion using direct simulation Monte Carlo method or solving the Navier–Stokes equations. It is found that during the descent, the recirculation zone under the surface shock wave first disappears and then reappears. The shock wave systems in the plume at different lander heights is analyzed, revealing that the formation of the recirculation bubble can be attributed to the total pressure loss due to gas crossing different wave structures. When the lander descends to a close proximity to the lunar surface, the recirculation bubble can even expand into the nozzle. Furthermore, this study investigated the effects of the recirculation bubble on lunar soil transportation by a gas–solid two-phase solver. It is shown that the recirculation bubble at low landing altitude will entrain the lunar dusts and result in a high ejection angle of the latter, thus aggravating the obstruction of surface observation for the safe landing. [ABSTRACT FROM AUTHOR]

Traditional methods of initiating oblique detonation waves (ODWs) using wedges and cones face a fundamental challenge in reconciling the need for rapid initiation with stable combustion, especially at low flight Mach numbers (Ma < 8). This study introduces an innovative initiation configuration involving a truncated cone. By utilizing Euler equations coupled with detailed hydrogen–air chemical reaction models, the wave dynamics induced by the truncated cone configuration are systematically explored. The findings reveal that the truncated cone configuration enables more rapid initiation of ODWs compared to conventional cones, while also preserving improved stability when contrasted with wedge. This behavior can be attributed to the planar flow characteristics in the post-shock field of truncated cone, generated by the upstream wedge-shaped shock, and the Taylor–Maccoll flow characteristics, caused by the downstream conical shock. Furthermore, the study delves into the initiation and morphological changes with respect to the inner radius and angle of the truncated cone. As inner radii or truncated cone angle increase, three initiation wave systems emerge: stable, oscillatory, and detached modes. Analysis of the dynamic variations in pressure and velocity within the induction zone highlights that the upstream oscillation originates from the flow velocity in the induction zone falling below the local Chapman–Jouguet velocity of normal detonation wave (NDW). However, the upstream region of the truncated cone exhibits more pronounced expansion effects, leading to momentum loss, and subsequently, the weakening and even vanishing of the NDW. This prompts the downstream oscillation of the initiation structure, instigating a cyclic oscillation pattern. [ABSTRACT FROM AUTHOR]

Two-dimensional, wedge-induced oblique detonation waves (ODWs) subject to periodic inflow are simulated using the reactive Euler equations with a two-step induction–reaction kinetic model. The focus of this work is how the periodic unsteadiness of a sinusoidal density disturbance with varying frequency and amplitude influences an initially established ODW structure. Three fundamental ODW structures with different transition types and inflow Mach numbers are disturbed, resulting in two types of triple-point formations: the main triple point (MTP) and the train of triple points (TTP). The TTP features multi-triple points arising almost simultaneously and traveling together, which has never been observed before. A parametric study and frequency analysis reveal that the MTP derives from forced destabilization, while the TTP derives from the combined effect of surface instability and inflow disturbance. Furthermore, a new phenomenon of MTP degeneration is observed for a proper inflow Mach number and disturbance amplitude. Finally, the oscillation amplitudes of unsteady ODWs are analyzed with respect to the Mach number and inflow disturbance, demonstrating the effects of transition type on surface unsteadiness. [ABSTRACT FROM AUTHOR]

Abstract In this study, we present a novel numerical model for simulating detonation waves on unstructured grids. In contrast to the conventional finite volume method (FVM), two types of moment comprising the volume-integrated average (VIA) and the point value (PV) at the cell vertex are treated as the evolution variables for the reacting Euler equations. The VIA is computed based on a finite volume formulation of the flux form where the conventional Riemann problem is solved by the HLLC Riemann solver. The PV is updated in a point-wise manner by using the differential formulation where the Roe solver is used to compute the differential Riemann problems. In order to increase the accuracy around discontinuities, numerical oscillations and dissipations are reduced using the boundary variation diminishing algorithm. Convergence tests demonstrated that the proposed model could achieve third-order accuracy with unstructured grids for reacting Euler equations. The high resolution property of the proposed method was verified based on simulations of several detonation wave propagation problems in two and three dimensions. In particular, the current model could resolve the cellular structures with fewer degrees of freedom for the unstable oblique detonation wave problem. These fine structures may be smoothed out by the conventional FVM due to the excessive amount of numerical dissipation errors. Importantly, a simulation of stiff detonation waves showed that the proposed method could capture the correct position of the reaction front whereas the conventional FVMs produced spurious phenomena. Thus, the proposed model can obtain highly accurate solutions for detonation problems on unstructured grids, which is highly advantageous for real applications involving complex geometrical configurations. [ABSTRACT FROM AUTHOR]

In this study, numerical simulations using Euler equations with detailed chemistry are performed to investigate the effect of fuel–air composition inhomogeneity on the oblique detonation wave (ODW) initiation in hydrogen–air mixtures. This study aims for a better understanding of oblique detonation wave engine performance under practical operating conditions, among those is the inhomogeneous mixing of fuel and air giving rise to a variation of the equivalence ratio (ER) in the incoming combustible flow. This work focuses primarily on how a variable equivalence ratio in the inflow mixture affects both the formation and characteristic parameters of the oblique detonation wave. In this regard, the present simulation imposes initially a lateral linear distribution of the mixture equivalence ratio within the initiation region. The variation is either from fuel-lean or fuel-rich to the uniform stoichiometric mixture condition above the oblique shock wave. The obtained numerical results illustrate that the reaction surface is distorted in the cases of low mixture equivalence ratio. The so-called “V-shaped” flame is observed but differed from previous results that it is not coupled with any compression or shock wave. Analyzing the temperature and species density evolution also shows that the fuel-lean and fuel-rich inhomogeneity have different effects on the combustion features in the initiation region behind the oblique shock wave. Two characteristic quantities, namely the initiation length and the ODW surface position, are defined to describe quantitatively the effects of mixture equivalence ratio inhomogeneity. The results show that the initiation length is mainly determined by the mixture equivalence ratio in the initiation region. Additional computations are performed by reversing ER distribution, i.e., with the linear variation above the initiation region of uniform stoichiometric condition and results also demonstrate that the ODW position is effectively determined by the ER variation before the ODW, which has in turn only negligible effect on the initiation length. [ABSTRACT FROM AUTHOR]

The properties of Mach stems in hypersonic corner flow induced by Mach interaction over 3D intersecting wedges were studied theoretically and numerically. A new method called 'spatial dimension reduction' was used to analyze theoretically the location and Mach number behind Mach stems. By using this approach, the problem of 3D steady shock/shock interaction over 3D intersecting wedges was transformed into a 2D moving one on cross sections, which can be solved by shock-polar theory and shock dynamics theory. The properties of Mach interaction over 3D intersecting wedges can be analyzed with the new method, including pressure, temperature, density in the vicinity of triple points, location, and Mach number behind Mach stems. Theoretical results were compared with numerical results, and good agreement was obtained. Also, the influence of Mach number and wedge angle on the properties of a 3D Mach stem was studied. Graphic abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The photocatalytic composites based on BiVO4, TiO2 nanotubes (TNT) and reduced graphene oxide (RGO) were synthesized by a one‐step hydrothermal synthesis method. The properties and structures of the samples were characterized by SEM, XRD, UV‐Vis DRS, Raman spectroscopy, photoluminescence spectroscopy and XPS. The effects of RGO‐TNT loading, pH, and dosage of catalysts on degradation efficiency were tested. The best removal results were occured on the condition that loading amount of RGO‐TNT was 10 %, solution pH 10, and catalyst dosage was 1.4 g L−1. The obtained ternary composite with 10 wt% RGO‐TNT exhibited a significant enhancement in photocatalytic efficiency due to the lower band gap with enhanced light absorption and a suppression in the recombination rates of the photogenerated charge carriers, and about 73 % of imidacloprid was degraded within 30 min under UV irradiation. Furthermore, BiVO4/RGO‐TNT‐10 can be reused for 6 times without obvious catalysis loss. Trapping experiments showed that hydroxyl radicals were the main active species in the imidacloprid photocatalytic degradation, and a possible photocatalytic mechanism was proposed based on the results of trapping experiments. [ABSTRACT FROM AUTHOR]

A normal detonation wave in a gaseous mixture is a transient, multidimensional structure containing triple points (TPs) that collide in pairs and then propagate oppositely. However, the TPs on an oblique detonation wave (ODW) almost propagate along the same direction in most studies. In this study, the reactive Euler equations coupled with a two-step induction–reaction kinetic model are used to solve a two-dimensional wedge-induced ODW. Two novel movement patterns are observed in most cases. Results show that the TPs of the ODW can propagate upstream and even stand on the wave surface. The movement patterns of TPs include downstream, upstream, and steady according to their propagation direction relative to the wedge. We find that the ratio of the post-ODW flow speed Uτ to the transverse wave speed UT dominates the TP movement types. When the speed ratio Uτ/UT is approximately equal to 1, the TPs can stand on the wave surface. Above unity, downstream TPs form, and upstream TPs correspond to a value smaller than 1. Furthermore, the inflow Mach number has little influence on UT, while Uτ changes significantly. This is largely due to the high sensitivity of the ODW angle to the inflow. The high heat release rate benefits upstream TPs, and steady TPs form under a large wedge angle. The results are confirmed by varying the inflow Mach number, wedge angle, and chemical parameters. [ABSTRACT FROM AUTHOR]

The high enthalpy shock tunnel is an important ground facility for the research of hypersonic flow. However, the expansion process of the high enthalpy flow in the nozzle is a typical flow with thermo non-equilibrium and chemical non-equilibrium, and the characteristic parameters of the free stream flow are difficult to be determined by direct measurement tools. With numerical solving axisymmetric Navier-Stokes equations coupling with two temperature model, the non-equilibrium flow characteristic in a high enthalpy shock tunnel under its typical experiment conditions is studied in this paper. The rule of enthalpy to the non-equilibrium characteristics is also studied. Results show that the uniform field at the nozzle exit can reach up to 75% of the nozzle exit diameter, which can offer sufficient space for model experiment. The nozzle free stream will be frozen at about 0. 4m after the nozzle throat. With the increase of enthalpy from 8. 4 to 19. 5MJ/kg, the non-equilibrium degree will increase with as enthalpy increases. At the low enthalpy, the increase will be more intense. [ABSTRACT FROM AUTHOR]

Investigating the self-reconstruction process of MOF-supported electrodes is of significant importance for understanding the reaction mechanisms in electrocatalytic oxygen evolution reaction (OER). By using 1,1′-ferrocenedicarboxylic acid (FcDA) as the ligand and NiFe foam (NFF) as the current collector, a self-supported T 50 NiFc-MOF/NFF electrode was synthesized through the introduction of triethylamine (TEA) to regulate the deprotonation process. The optimized T 50 NiFc-MOF/NFF exhibited excellent electrocatalytic OER performance, requiring only 217 mV to drive a current density of 10 mA cm−2, surpassing commercial RuO 2. Additionally, the T 50 NiFc-MOF/NFF showed a remarkable electrocatalytic stability of over 70 h. The unique 2D MOF nanoarrays and strong coordination bonds between the metal and ligand in the as-prepared self-supported electrode contribute to the enrichment of electrochemical active sites and catalytic stability. Through a self-construction process, the 2D MOF nanoarrays on the electrode surface were in-situ converted into a more active metal-LDH during alkaline electrocatalysis, which played a crucial role in improving the electronic structure of the electrode, demonstrating its importance in achieving efficient OER processes. [Display omitted] • 2D NiFe-MOF nanoarrays were in situ grown on alloy foams. • The optimal T 50 NiFc-MOF/NFF shows excellent electrocatalytic OER performance. • The self-reconstruction of MOFs occurred during the OER process. [ABSTRACT FROM AUTHOR]

The development of highly dispersed and ultra-small size cobalt-loaded catalysts is crucial for achieving efficient and low secondary pollution in peroxymonosulfate (PMS) activation processes. Herein, a phosphorus-doped carbon nitride (PCN) loaded with CoO quantum dot catalyst (Co 80 -PCN) was derived from the mixture of BINAP-CoCl 2 complex (BINAP = 1,1′-binaphthyl-2,2′-diphosphine) and carbon nitride (CN). Structural studies revealed that cobalt oxide quantum dots with an average diameter of 9.99 nm were evenly and securely attached to the PCN substrate. The optimal Co 80 -PCN/PMS system demonstrated an almost 100% degradation efficiency of sulfamethoxazole (SMX, 10 mg/L) within 15 min, with a reaction rate constant of 0.3341 min−1, which was 30.1 times higher than that of the CN/PMS system. This outstanding degradation performance could be primarily attributed to the enhanced catalytic activity of CoO quantum dots and the improved electronic structure resulting from P-doped CN. This work offers valuable insights for the future design of carbon material loaded quantum dot catalysts. [Display omitted] • By introducing a Co-complex, CoO quantum dots immobilized on P-doped CN. • Rich CoO quantum dots and improved electronic structure boosting PMS activation. • The radical and non-radical mechanisms were involved in the Co 80 -PCN/PMS system. • In real water bodies, the degradation efficiency can reach over 90% within 6 min. [ABSTRACT FROM AUTHOR]

Oblique detonation wave (ODW) reflection before an expansion corner leads to a sophisticated wave complex, whose steadiness is critical to achieve a practical oblique detonation engine. Both steady and unsteady wave complexes have been observed before, but the features of unsteady wave dynamics with related unsteadiness rules are still unclear so far. In this study, the ODW reflections before an expansion corner have been simulated using the reactive Euler equations with a two-step induction–reaction kinetic model, and the wave complex structures and dynamics have been analyzed correspondingly. Three subsonic zones have been distinguished, and their interactions were found to determine the wave complex steadiness. The main subsonic zone derives from the ODW reflection, which locates behind the Mach stem, while two other subsonic zones form due to the shock reflection downstream. The two downstream subsonic zones might travel upstream and combine with the main subsonic zone, resulting in two different unsteadiness modes. These wave complex dynamics were analyzed with respect to the deflection location, deflection angle and inflow Mach number, leading to the boundaries of combustion modes and ascertaining the rule of mode regime. Some transient phenomena related with the flow instability have been also discussed, clarifying fine flow structures further. [ABSTRACT FROM AUTHOR]

Various oblique detonation waves (ODW) structures have been investigated with the application background of ramjet engine, but effects of forebody compression have attracted little attention before. Two forebody compression models, the ESS (equal-strength-shock) compression and the SI (shock-isentropic) compression, have been introduced to study their effects on the ODW structure and thermal performance. Numerical results demonstrate that the compression method influences the ODW structure obviously, including the initiation location and the OSW–ODW transition type. Compared with the ESS compression, the SI compression leads to the downstream movement of initiation location, and the transition prefers to be abrupt rather not smooth. On the thermal features, the total pressure recovery is used to analyse the difference as the key parameter on the potential of engine impulse. The ESS compression corresponds a low total pressure loss when considering only the combustion process, while the SI compression performs better when considering the inlet–combustion whole process. Analysis on total pressure recovery gives the average total pressure recovery with flight Ma, altitude, and wedge angle. It is pointed out the SI compression has two shortcomings, including a long initiation length and a low total pressure recovery of combustion process, which should be considered in the future application. [ABSTRACT FROM AUTHOR]

In this work, AgI nanoparticles were anchored on decahedron-like MIL-125(Ti) through wet precipitation method, and the photocatalytic activities were analyzed by tetracycline (TC) degradation rates under simulated sunlight. The structures, morphologies, valence bonds, optical absorption properties, charge separation efficiencies of the prepared samples were tested by XRD, SEM, EDS, XPS, UV–Vis DRS and PL spectroscopy. Compared with pure MIL-125(Ti), AgI@MIL-125(Ti) displayed excellent photocatalytic performance on TC degradation. When the mass fraction of AgI in AgI@MIL-125(Ti) was 10 %, AgI@MIL-125(Ti)-10 % displayed the best photocatalytic efficiency, which 96.9 % of TC was removed under simulated sunlight for 30 min. The results of active species trapping experiments and ESR tests showed that the Z-Scheme heterojunction between AgI and MIL-125(Ti) promoted the separation of photogenerated charges. Furthermore, a part of Ag+ were reduced to Ag NPs in the process of photocatalytic reaction, which constructed a cross-linking bridge for the charges at the interface of AgI and MIL-125(Ti) and further accelerated the electron transmission. The intermediate toxicity experiments proved that the toxic structures are destroyed in TC solution after MIL-125(Ti)-10 % photocatalytic degradation, and the toxicity of the reaction system was reduced effectively. In this work, a novel Z-scheme AgI@MIL-125(Ti) photocatalyst was fabricated by loading AgI on decahedron-like MIL-125(Ti) through wet precipitation method. AgI@MIL-125(Ti)-10 % displayed the best photocatalytic activity, which 96.9 % of TC was removed under simulated sunlight for 30 min. The Z-Scheme heterojunction between AgI and MIL-125(Ti) promoted the separation of photogenerated charges. Furthermore, a part of Ag+ were reduced to Ag NPs in the process of photocatalytic reactions, which constructed a cross-linking bridge for the charges at the interface of AgI and MIL-125(Ti) and further accelerated the electron transmission. The intermediate toxicity experiments proved that the toxic structures are destroyed in TC solution after MIL-125(Ti)-10 % photocatalytic degradation, and the toxicity of the reaction system was reduced effectively. [Display omitted] • The AgI@MIL-125(Ti) Z-scheme were successful synthesized by a simple wet precipitation method. • No more toxic intermediates were produced during photocatalytic degradation. • Ag NPs constructed a cross-linking bridge at the interface of AgI and MIL-125(Ti), accelerating electron transmission. • TheZ-scheme has a broad prospect in practical application as a photocatalyst. [ABSTRACT FROM AUTHOR]

Oblique detonation waves (ODWs) have been studied widely as the basis of detonation-based hypersonic engines, but there are few studies on ODWs in a confined space. This study simulates ODW reflection on a solid wall before an outward turning corner for a simplified combustor–nozzle flow based on a two-step kinetic model. Numerical results reveal three types of ODW structures: stable, critical, and unstable. When the reflection occurs at the turning point, the stable ODW structure remains almost the same as before reflection. When the wave reflects at the wall before the turning point, either the critical structure or the unstable structure arises, which has never been investigated before. Both structures have the same initial two-section detonation surface: but the critical one becomes stationary at a certain position, while the unstable one keeps traveling upstream. By adjusting the location of the expansion wave and degree of the turning angle, the difference of the two structures is attributed to the thermal choking appearing only in the unstable structure. The thermal choking is achieved by the merging of subsonic zones, whose dependence on the various parameters is discussed. [ABSTRACT FROM AUTHOR]

Gaseous detonation has complicated cellular surface, whose comprehensive investigation is critical not only to the detonation physics but also the detonation engine development. Because measuring the high-resolution dynamic surface is beyond the present experimental technical skills, we propose a reconstruction method of detonation wave surface based on post-surface flow field. This method combines two technologies, the proper orthogonal decomposition (POD) in fluid research and the artificial neural network (ANN) in machine learning research. POD is employed to extract the main features of flow fields, and the pre-trained ANN builds up the connection between the reduced coefficients of full flow fields and post-surface flow fields. The reconstruction is tested through the numerical results from one-step irreversible heat release model, displaying a good performance in both cellular normal detonations and unstable oblique detonations. The method may provide a universal frame for the detonation research, and has the potential to be employed in other numerical and experimental results. [ABSTRACT FROM AUTHOR]

A simple and feasible hydrothermal method was employed to regulate the surface charge and growth degree of active facet of BiVO4 by varying the pH value of precursor. The prepared products were characterized by XRD, Raman spectra, SEM, N2 adsorption and desorption, zeta potential, and UV–Vis DRS. It is found that with increasing the pH value, not only do the phase composition, micro-morphology, specific surface area, and light absorption of BiVO4 products have obvious changes, but so do the surface charge and growth degree of {010} facet. A possible formation mechanism is proposed on the basis of the characterization results. The photocatalytic activities were evaluated by the degradation of rhodamine B solution under visible light irradiation. The results showed that monoclinic scheelite BiVO4 (m-BiVO4) particles prepared at pH 4 exhibit the maximum adsorption capacity and the best photocatalytic performance, which was mainly attributed to the negatively charged surface. On the contrary, the similar degradation rate and kinetic constant of the m-BiVO4 prepared at pH 3 could be ascribed to the preferential growth of {010} facets. [ABSTRACT FROM AUTHOR]

Mesocrystals have attracted more attention owing to their unique structures and properties. Nevertheless, facile and green synthesis of well‐defined mesocrystals still remains a significant challenge. Herein, one‐dimensional (1D) rodlike monoclinic scheelite phase BiVO4 (mBiVO4) mesocrystals having superstructures orderly assembled by mBiVO4 nanoparticle building blocks, were created via a facile solvothermal method in the glycerol (Gly)/water mixed solvent without any additives. By adjusting the dosage of Gly and pH value of the reaction system, the microstructure of BiVO4 can be accurately regulated. The obtained samples were carefully characterized by XRD, SEM, TEM, HRTEM, BET, FTIR, PL and UV‐vis techniques. The lower pH value and the higher dosage of Gly were propitious to form rodlike mBiVO4 mesocrystals. Of course, the kind and concentration of reaction species in the system and the assembly force were affected by the dosage of Gly and pH value. The possible formation mechanism of the BiVO4 mesocrystals was proposed on the basis of these analyses. The optimized rodlike mBiVO4 mesocrystal prepared with 8 mL of Gly at pH 2 exhibited the highest photocatalytic degradation activity for methylene blue (MB) under simulated sunlight irradiation, which could be attributed to its phase composition, higher surface area, stronger light absorption and 1D rodlike morphology with short L/D ratio which may increase the separation efficiency of photogenerated electrons and holes. [ABSTRACT FROM AUTHOR]

Oblique detonation waves (ODWs) in stoichiometric acetylene-oxygen mixtures, highly diluted by 81–90% argon, are studied using the reactive Euler equations with a detailed chemistry model. Numerical results show that the incident Mach number M 0 changes the ODW initiation structure, giving both the smooth transition in the case of M 0 = 10 and the abrupt transition in the case of M 0 = 7. By comparing results of numerical simulation and theoretical analysis, the initiation processes are found to be chemical kinetics-controlled regardless of M 0 , different from those in hydrogen-air mixtures which are wave-controlled in the low M 0 regime. The argon dilution effect on the initiation morphology is investigated, showing that the structures are determined by the dilution ratio and M 0 collectively. However, the initiation length is found to be independent of the dilution ratio and only determined by M 0 , which is attributed to the competing effect of the high density and high temperature. [ABSTRACT FROM AUTHOR]

Stoichiometric acetylene-oxygen mixtures diluted by argon are widely used in normal detonation waves but have not yet been used in oblique detonation waves (ODWs). The present study simulates ODWs in acetylene-oxygen-argon mixtures, with a dilution ratio Φ = 50%-90%, using the reactive Euler equations with a detailed chemistry model, and describes the characteristics of acetylene ODWs. Similar to ODWs in hydrogen-air mixtures, the transition from the oblique shock wave to ODW may be either abrupt or smooth and the effects of Φ are investigated with a variable incident Mach number M0. When M0 changes between 8 and 10, the transition is abrupt in the case of Φ = 50%, while it is smooth in the case of Φ = 90%. In the case of Φ = 70%, a high M0 corresponds to a smooth transition, while a low M0 corresponds to an abrupt transition. A further study on the initiation mechanism was performed by comparing the numerical initiation length with the length obtained via the constant-volume combustion calculation, which demonstrated that the initiation is kinetic-controlled in the cases of Φ = 70% and 90%, but wave-controlled in the case of Φ = 50% with M0 below 8.5. Moreover, an initiation structure featured by two-shock in the product was observed for the first time, and its formation mechanism is qualitatively discussed and compared to hydrogen ODWs. [ABSTRACT FROM AUTHOR]

A numerical study was performed to investigate the detailed effects of activation energy Ea on the oblique detonation wave surface instability. Numerical simulations were performed using an ideal reactive flow model given by the inviscid Euler equations with one-step irreversible Arrhenius reaction kinetics. The numerical results demonstrate two types of unstable structures following the initial smooth surface after detonation initiation. One exhibits by a "saw-tooth" reactive front and the other exhibits by a "keystone" feature. To quantify the destabilization processes, two characteristic length scales, L1 and L2, are defined statistically to be the length of the smooth detonation surface before the appearance of instabilities and the length of the unstable surface before the first cellular structure with the onset of right-running transverse waves, respectively. Their dependence on Ea was simulated and analyzed. In general, both lengths decrease with increasing Ea, making the surface more unstable. However, with increasing Ea, the high temperature sensitivity of the mixture causes an abrupt explosion in the initiation region, introducing a high overdriven surface and suppressing the instability. With the balance between the destabilizing effect of Ea and the stabilizing effect of increasing overdrive factor, both L1 and L2 are found to approach a near-constant value in the high Ea limit. [ABSTRACT FROM AUTHOR]

[Display omitted] • Highly selective MIM was approached for efficient separation of determinand. • Dopamine-embedded porous sleeve was proposed for enhanced molecular imprinting. • Homogeneous imprinted sites spread throughout interpenetrating-bicontinuous porous. • Stable selectivity in regeneration cycles ensures the long-term availability. • Insight of polymerization mechanisms were obtained by DFT calculations. The molecularly imprinted membrane has shown irreplaceable superiority in advanced water treatment, biochemical purification, and in most cases, pretreatment of environmental determinands. However, effective and controllable construction of imprinted sites in membrane-based interpenetrating pores is as yet the significant bottleneck. Herein, we proposed a thermally induced strategy on the polydopamine-embedded molecularly imprinted membrane (DEMIM) for enhanced selective separation of Ciprofloxacin (CIP). The porous sleeve was constructed with polyvinylidene fluoride (PVDF), together with the integrated β-cyclodextrin (β-CD) for hydrophilicity and anti-fouling requirements. Based on the thermally induced operation, polydopamine (PDA) embedded in the membrane matrix acted as a secondary reaction platform, effectively improving the interpenetrating-bicontinuous porous morphology and enhancing the availability of imprinted sites in microchannels. The imprinting polymerization was carried out by the efficient thiol-ene Click reaction, which was investigated in depth by density functional theory (DFT) calculations. The impressive relative separation factor (2.33–4.59) and permselectivity (9.50–12.50) indicated the superior availability of DEMIM for the selective separation. The remarkable regeneration performance (fluctuation in 8.4%∼10.8%) demonstrated the feasibility of the porous membrane-based sleeve for regeneration of molecular imprinting. The approach and methodologies achieved in this work will potentially promote the development of novel molecularly imprinted membranes for advanced applications. [ABSTRACT FROM AUTHOR]

• A deep learning method based on CNN is first applied in the study of detonation wave. • Compared with traditional MLP method, this CNN approach performs much better. • The well-trained CNN shows a certain generalization capability and robustness. Detonation wave surface is composed of lead shock and reactive front, which are difficult to be measured simultaneously, so it is necessary to reconstruct the detonation surface. In this study, a reconstruction method is proposed for predicting lead shock from reactive front to obtain a full cellular detonation surface. The reconstruction uses a convolutional neural network (CNN) with the advantages of feature extraction and data dimensionality reduction, and the proposed method has been verified by data from numerical simulations in this work. The results indicate that this method performs much better than the traditional multi-layer perceptron (MLP), benefiting from the advanced architecture of CNN. Furthermore, effects of hyper-parameter choice have been tested, and the generalization capability of trained CNN for different activation-energy cases are also discussed. [ABSTRACT FROM AUTHOR]