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Blockchain serves as a replicated transactional processing system in a trustless distributed environment. Existing blockchain systems all rely on an explicit ordering step to determine the global order of transactions that are collected from multiple peers. The ordering consensus can be the bottleneck since it must be Byzantine-fault tolerant and can scarcely benefit from parallel execution. In this paper, we propose an ordering-free architecture that makes ordering implicit through deterministic execution. Based on this novel architecture, we develop a permissioned blockchain system NeuChain. A number of key optimizations such as asynchronous block generation and pipelining are leveraged for high throughput and low latency. Several security mechanisms are also designed to make our system robust to malicious attacks. Our geo-distributed experimental results show that NeuChain can achieve 47.2--64.1X throughput improvement over HyperLedger Fabric and 1.6--12.2X throughput improvement over the state-of-the-art high performance blockchains.

Isoflavones in soybean seed and root exudates are host-specific signal molecules for Phytophthora sojae to recognize its host, soybean. G protein and calcium signaling pathways are involved in the chemotaxis of zoospores in the recognition of isoflavones. The role played by non-host-specific signaling molecules (sugars and amino acids) found in seed and root exudates on zoospore chemotaxis and mycelial growth was studied. The transcriptome of P. sojae responding to aspartic acid (Asp) and glucose (Glc) was analyzed in parellel by the RNA-seq method. We found that the relative in situ concentrations of amino acids and sugars significantly promoted zoospore chemotaxis, as do isoflavones. Transcriptomics showed that both similarities and differences existed in response mechanisms of P. sojae to Asp and Glc. Asp and Glc activated mitogen-activated protein kinase signaling pathways and the phosphatidylinositol signaling system but not the G-protein signaling pathway, which have been reported to be responsible for zoospore chemotaxis. In addition, ubiquitin-mediated proteolysis and ATP binding cassette transporters were also activated by Asp and Glc. Meanwhile, the glutathione signaling pathway uniquely participated in the response of P. sojae to Asp but was not involved in the response process to Glc, which will be evaluated in another study. Our results provide new insights into the molecular mechanisms of zoospore response to Asp and Glc.

Phytophthora sojae does not infect nonhost maize (Zea mays) but infects nonhost common bean (Phaseolus vulgaris) under inoculation. Soybean seed exudates participate in mediating host resistance to P. sojae before infection. This study aims to elucidate the role of seed exudates in mediating the nonhost resistance of maize and common bean to P. sojae before infection. The behaviors of P. sojae zoospores in response to the seed exudates were determined using an assay chamber and a concave slide. The proteomes of P. sojae zoospores in response to the seed exudates were analyzed with the tandem mass tag method. The key proteins were quantitatively verified by parallel reaction monitoring. Maize seed exudates exerted a repellent effect on zoospores of P. sojae. This result explains why zoospores sense repelling signaling molecules in maize seed exudates that weaken and strongly inhibit chemotaxis signals in the phosphatidylinositol signaling pathway and arachidonic acid metabolism pathway. Common bean seed exudates did not exhibit any attraction to the zoospores because the guanine nucleotide-binding protein signaling pathway, which is responsible for transmitting chemotactic signals, had no significant change. The proteins protecting the cell membrane structure were significantly downregulated, and the early apoptosis signal glutathione was enhanced in zoospores responding to common bean seed exudates, which resulted in dissolution of the cysts. Maize and common bean seed exudates mediate part of the nonhost resistance to P. sojae via different mechanisms before infection. The immunity of maize to P. sojae is caused by the repellent effect of maize seed exudates on zoospores. Common bean seed exudates participate in mediating nonhost resistance by dissolving the cysts.

Sub-23nm particles emission from the light-duty vehicle is widely discussed now and possible to be counted into the next stage emission legislation, such as Euro7. In this article, 16 China6 gasoline vehicles were tested over the WLTC and two surrogate RDE lab cycles for particulate number (PN) emission, the difference between PN23 (particle size >23nm) and PN10 (particle size>10nm) emission was analyzed. Testing results showed that the average PN10 emission increased 59% compared to PN23, which will bring great challenges for those vehicles to meet the future regulation requirement if sub-23nm particle is counted. The sub-23nm particles emission was proportional to the PN23 particles emission and generated mostly from the cold start or the transient engine conditions with rich combustion. Compared to the proposal of Euro 7, PN10 emission from some tested vehicles will need further two orders of magnitude reduction. With the adoption of an advanced gasoline particulate filter (GPF) sample, the most challenging vehicle achieved the PN10 emission level of 3.3E10 #/km over the surrogate RDE cycle with GPF filtration efficiency above 99% and fulfilled the potential EU7 requirement.

As the official proposal for emission regulation Euro 7 has been released by European Commission, PN above 10nm is taken into consideration for the ultrafine particulate emissions control. The challenges of GPF filtration efficiency emerge for the light-duty manufactures to meet the future emission standards. In the present study, a China 6 compliant vehicle was tested to reveal its performance over the China 6 standards and potential to meet the upcoming Euro 7. Three GPF product types (Gen 1, Gen 2, and concept Gen 3) were mounted to the tested vehicle. WLTC tests were conducted on chassis dynamometer in laboratory as well as a self-designed aggressive cycle (“Base Cycle”) tests. To explore the GPFs performance for PN emissions above 10nm against the proposed limit 6.0E11 #/km, PN emission above 10nm were measured in our laboratory tests for both engine out and tailpipe as well as the PN emission above 23nm. In addition, worst case RDE tests were carried out on the real road with PEMS. It was found that, when including particles down to 10nm, further improvement is needed for the current system, and the Gen 2 and concept Gen 3 products could be a promising path to meet the proposed standards with much higher filtration efficiency. Combined with possibly further extended RDE boundary conditions in Euro 7, the test results suggested that higher filtration efficiency filter products are likely required to comply with the tightened emission regulations.

Bifacial semitransparent perovskite solar cells (BS-PSCs) have broad application prospects in the field of building-integrated photovoltaics, tandem solar cells as well as transparent chargeable devices. To fabricate high-performance BS-PSCs, the rear transparent electrode is one of the major obstacles should be overcome. Here, we develop a MoOx/Cu/Ag/MoOx multi-stacked electrode by thermal evaporation, and utilize it as a rear transparent electrode in the fabrication of high-performance n-i-p structure BS-PSCs. It is demonstrated that the minimum thickness required to obtain a continuous Ag film is reduced from 15 nm without the seed layer to 10 nm and the optical and electrical properties of multilayer transparent electrode are significantly enhanced. As a result, the BS-PSC device achieves the optimal power conversion efficiency of 13.44% at indium tin oxide side and 10.25% at MoOx/Cu/Ag/MoOx rear transparent electrode side, along with an average 8.67% optical transmittance for the visible light (400–800 nm) simultaneously. This work provides a promising approach to fabricate high-performance semitransparent and bifacial-operable optoelectronic devices in the future.

Friction heat generation of ball screw nut pair may lead to changes in the contact state between ball and raceway. Different contact states may result in a change in the intensity of the heat source of the nut pair, which in turn affects the contact state again until a certain balance is reached. At present, the time-varying research of the heat source of the screw nut pair is mainly carried out from the boundary conditions and the location of the heat source, without considering the influence of the internal structure change of ball screw nut pair. In order to fill this gap, a time-varying thermoelastic coupling analysis method for heat source of screw nut pair is proposed. In this paper, the contact model of ball and raceway is established by the elastic theory of plane strain, and the theoretical solution of the contact point displacement of ball raceway under thermal influence is derived by combining with the thermoelastic theory. Then, through the method of polygon equivalence of ball and raceway profile, the contact angle variation process of ball and raceway under the coupling effect of heat and structure was described geometrically, and the variation rule of heat source intensity was further obtained. In addition, the nut temperature variation rule was obtained through the temperature field experiment of the screw nut pair. The temperature variation curve of the nut pair under heat source induction in the actual working condition was fitted after the temperature drop data and the ambient temperature data were processed. By comparing the theoretical temperature variation curve under constant heat source induction, the heat source variation curve of the nut pair under the actual working condition was finally fitted. The correctness of the thermoelastic theory analysis is further verified. The method proposed in this paper analyzes the variation law of the heat source intensity from both theoretical and experimental perspectives, which has important reference significance for the study of the thermal characteristics of the ball screw system.

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In the performance test of a compressor, the overstrain alarm of a rotor blade occurred and it was thought to be caused by a large-sized inlet probe. To explain and further avoid the occurrence of this phenomenon, the influences of probe strut configuration on the vibration strain of the compressor rotor blade and the corresponding flow mechanism are studied by using a one-way fluid-structure coupling calculation method. Firstly, the probe strut is simplified as a cylinder with a diameter of 10 mm and located upstream of the inlet stator with the strut wake impinging on the stator blade according to the compressor test. Then, the three scenarios are considered: moving the strut away from the stator blade in axial direction, shifting the strut half of the stator pitch circumferentially, and reducing the strut diameter. The analysis results show that the characteristics of blade vibration are determined by the excitation force on the rotor blade. Under the interaction between the large-sized strut and the compressor, in addition to the excitation force with the strut passing frequency, a force with a lower frequency, namely, the strut-wake-induced frequency, is also observed. The amplitude of the excitation force on the rotor blade depends on the probe configuration. When one of the excitation force frequencies is close to a natural frequency of the rotor blade, the blade resonates, and the amplitude of blade strain varies with the amplitude of the excitation force. In order to reduce the adverse effect of upstream strut wake on the compressor rotor blade vibration, the inlet probe strut should be designed with a smaller diameter and be placed further upstream of the stator in such a way that the strut wake vortex passes through the midpassage of the following stator.

A facile synergetic strategy is reported for the synthesis of the LiMnO2@VXC-72R composite microspheres by applying spray-drying technique with nanosized LiMnO2 particles as host material and conductive carbon black (VXC-72R) as dispersing agent. In this hybrid structure, LiMnO2 nanoparticles promote the lithium-ion diffusion due to the nanosized diffusion distance, whereas well-distributed VXC-72R suppress the aggregation of LiMnO2 nanoparticles and enhance the electronic conduction. Moreover, the micro-sized spherical morphology with low specific surface area is conducive to reducing the contact area between electrolyte and composite cathode, which inhibit the manganese dissolution. Benefiting from their synergistic effect, the LiMnO2@VXC-72R composite microspheres achieve the maximum discharge capacity of 187.3 mAh g−1 with good cycling stability at 0.1 C. After 50 cycles, the discharge capacity of composite cathode is still maintained at 173.2 mAh g−1, which is significantly higher compared to the primary LiMnO2 particles. Moreover, the LiMnO2@VXC-72R composite microspheres exhibit outstanding rate performance with high discharge capacity.

Differential effects of the seed exudates of susceptible and resistant soybean cultivars Sloan and Williams 82 on the zoospores of soilborne pathogenic Phytophthora sojae are not clear. This study aims to elucidate the role of the seed exudates in the host resistance of soybean against P. sojae during prior to infection. The response behaviors of P. sojae zoospores to the seed exudates were performed in an assay chamber and concave slide, the proteomes of P. sojae zoospores treated with the seed exudates were analyzed by TMT method. The expression of genes encoding key proteins was quantified by qRT-PCR. The zoospores of P. sojae exhibited significant chemotaxis to the both seed exudates and a stronger attracted was found to the seed exudates of Sloan. The seed exudates of Sloan also had a stonger promotion than that of Williams 82 on encystment of zoospores. During the responding process, the key proteins in zoospores related to chemotaxis were upregulated, the upregulation fold of these proteins in responding to Sloan was higher than that of Williams 82. Proteins differentially expressed promote the encystment of zoospores. The changes in expression of these proteins was several fold higher in the zoosprores exposed to the seed exudates of Sloan than that of Williams 82. Evidence of differential changes in protein expression in P. sojae zoospores exposed to the seed exudates of both soybean supports the differential developmental behaviors such as chemotaxis and encystment of the zoospores in responding to the two seed exudates.

It has been reported that the root exudates of nonhost maize inhibit

Gasoline particulate filter (GPF) is a cost-effective solution to particle number emissions from gasoline direct injection vehicles. Filtration efficiency, as a key parameter of GPF, was usually assessed at chassis level over regulatory drive cycles. However, the promulgation of real driving emission (RDE) requirements in the EU and Chinese regulations necessitates evaluations based on non-legislative cycles to guarantee the on-road emissions are compliant to regulatory requirements. In this research, two aggressive drive cycles, RTS95 at 23degC and modified RDE at 0degC, were complemented to the WLTC to evaluate the filtration efficiency of a catalyzed GPF (cGPF) in fresh conditions to obtain the so-called "worst-case" filtration efficiency. In the WLTC, RTS95, and simulated RDE tests, the filtration efficiency of the test cGPF was 51.1%, 41.3%, and 85.1% respectively. In the simulated RDE test, the test cGPF filtrated solid particles with a diameter above 23 nm and 10 nm at a similar efficiency. Increased filtration efficiency with heavier soot load could offset the relatively low filtration efficiency in cold-start and warm-up durations, hence the filtration efficiency for a clean cGPF showed higher sensitivity to cycle length over driving dynamics and testing temperature. In acceleration events with cGPF mounted, the particle diameter where number concentration peaked decreased as the engine warmed up. In deceleration events, bimodal and trimodal particle number size distributions with much lower concentrations were observed.

Isoflavones in soybean seed and root exudates are host-specific signal molecules for

In recent years, public transport has been developing rapidly and producing large amounts of traffic data. Emerging big data-mining techniques enable the application of these data in a vari...

The introduction of nanostructures is an effective method to boost the photovoltaic performance of hybridized organic-inorganic halide perovskite-film solar cells. Taking into account their excellent light-scattering in the ultraviolet–visible range and their chemical inertness, silicon ( Si ) nanorods can be incorporated into the perovskite-film solar cells to enhance the light harvesting of the devices. By depositing Si nanorods between the prepared film and the substrate, the light scattering induced by the Si nanorods significantly promoted light absorption of the films. Moreover, resulting from the incorporation of Si nanorods, the enlarged grain size and compact structure of the films prolonged the lifetime of the carriers, which promoted the photoelectric properties of the perovskite films. By the appropriate incorporation of Si nanorods, the photovoltaic conversion efficiency of the CH 3 NH 3 Pb(Br 0.25 I 0.75 ) 3 -film-based solar cell was increased from 12.6% to 14.9% and the relative stability of the devices under dark humidity was improved. This strategy of employing low-cost and easily prepared Si nanorods to enhance the light harvesting of perovskite photovoltaic devices could be applied to photovoltaic devices based on perovskite films with other compositions.

Surface engineering of crystalline silicon (c-Si) is the core of Si-based semiconductor devices. The current commercially available c-Si solar cells achieve this by making use of a conventional thin dielectric film passivation system (TDFPS), including SiO2, Al2O3, SiNx:H and hydrogenated amorphous silicon (a-Si:H) in industry. However, the TDFPS requires high-vacuum and/or high-temperature conditions, which hinders efforts to further reduce the costs of device fabrication. A revolutionized approach to circumvent these issues involves the replacement of TDFPS with new material system which can also achieve high-quality passivation on c-Si surface. Here, we successfully establish and implement a functional group passivation system (FGPS) using a series of functional materials with a sulfonic functional group -SO3H, such as ‘poly(2-acrylamido-2-methylpropanesulfonic acid)’ (PAMPS) and ‘polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene, sulfonated, cross-linkable’ (PS-b-PERB), which can achieve a highly effective passivation on Si surface, resulting in power conversion efficiencies up to 20% when they are applied in the front surface engineering of interdigitated back contact (IBC) solar cells. Furthermore, the FGPS materials inherently allow passivation layer fabrication in lowtemperature and high-vacuum-free conditions. This work provides novel low-cost material strategies without compromise of performance for c-Si surface engineering in the future Si-based photovoltaics.

Flue gas lead emission during sludge incineration damages to human health and ecological environment seriously. Therefore, a denitrifying bio-trickling filter (DNBTF) for lead removal in flue gas from sludge incineration was investigated. Lead removal efficiency was up to 90.7% in 60 days' operation. Lead speciation in biofilms of DNBTF consists of 84.27% residue lead, 15.18% organic bound lead, and less than 1% exchangeable and reducible lead. Lead resistant bacteria and lead resistant-denitrifying bacteria accounted for 85.04% and 58.25%, respectively. Lead resistant microorganisms(Pseudomonas, Azoarcus, Stappia, Pararhodobacter, Paracoccus, Azospirillum, Hyphomonas, Rhodobacter, Polymorphum, Brevunimonas, Stenotrophomonas) could resist the toxicity of Pb

In order to focus on the injury mechanism of electric cyclists in the collision accident between right turn of truck and electric bicycle, Pc-Crash is used to value the injury of the electric cyclist in this paper. Through repeated tests in Pc-Crash, it was found that two dynamic response process were existed. The electric bicycle and cyclist collided with truck, and the electric bicycle and cyclist were thrown to the ground due to the impact force. Finally, they were crushed under certain conditions. The multi-rigid-body truck model is built on the theories of multi-rigid-body modeling and multi-rigid-body collision to get the value of the crushed part which the single rigid model can't calculate. After that, we analyze HIC, continuous 3 ms resultant acceleration of chest, the shear force of femur and leg, based on the electric bicycle speed, the mass of electric bicycle and cyclist, the height of cyclist's seat. We found that when the electric cyclist is not crushed by the truck, the value of each damage index is below the threshold. But when the cyclist is crushed by the truck, the damage index of the part where the cyclist is crushed exceeds the threshold, and causes fatal injury to the cyclist. So, reducing the possibility of crushing can improve the safety level of electric cyclists.

Purpose: Phytophthora sojae does not infect the nonhost maize (Zea mays L.) but could infect the nonhost common bean (Phaseolus vulgaris L.). Soybean seed exudates participate in mediating host resistance to P. sojae before infection. This study aimed to elucidate the role of nonhost seed exudates in mediating nonhost resistance to P. sojae before infection. Methods: The response behavior of P. sojae zoospores to the seed exudates was determined using an assay chamber and a concave slide, and the proteomes of P. sojae zoospores treated with the seed exudates were analysed with the tandem mass tag (TMT) method. The key proteins were quantified by parallel reaction monitoring (PRM).Results: Maize seed exudates exerted a repellent effect on zoospores, whereas common bean seed exudates did not exhibit any attraction to zoospores but could dissolve the cysts. The key proteins related to zoospores chemotaxis showed no significant changes in response to maize seed exudates, but the key proteins in arachidonic acid pathway were downregulated and controlled the repellent behavior of zoospores. Proteins protecting the cell membrane structure were significantly downregulated in zoospores responding to common bean seed exudates, which confirmed the bacteriolytic effect of common bean seed exudates on cysts. Conclusion: Maize and common bean seed exudates mediate part of the nonhost resistance via different mechanisms prior to P. sojae infection. The immune of maize to P. sojae is due to the repellent effect of maize seed exudates on zoospores. Common bean seed exudates participate in mediating nonhost resistance by dissolving cysts.

Hydrogenated nanocrystalline silicon oxide/hydrogenated amorphous silicon oxide (nc-SiOx:H/a-SiOx:H) multilayer films were fabricated using very-high-frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) technique by alternate deposition of nc-SiOx:H and a-SiOx:H at a low substrate temperature of 220 °C. The effects of the amount of oxygen incorporation in the nc-SiOx:H sublayers on the structural and photoluminescence (PL) properties of nc-SiOx:H/a-SiOx:H multilayer films were investigated by transmission electron microscopy, Raman scattering, UV–VIS-NIR absorption spectra, steady and time-resolved PL spectra. As the amount of oxygen incorporation increases, the crystalline volume fraction of multilayer films decreases, while the intermediate-range order of multilayer films firstly increases and then decreases. Strong room temperature PL has been observed in the multilayer films and the correlation between structural and PL properties is discussed. This low-temperature procedure for fabricating nc-SiOx:H/a-SiOx:H multilayer films can provide powerful impetus for the further development of optoelectronic devices based on Si-NCs.

In this paper, the two-step sequential deposition method was used to prepare the CH3NH3PbBrXI3-X films by introducing CH3NH3Br in the precursors. The surface morphology of the PbI2 films was controlled by anti-solvent extraction (ASE) to improve the microstructure and photo-physical properties of the perovskite films. It was noteworthy that, compared to the compact PbI2 films, the porous PbI2 films facilitated the growth of crystals and bromine incorporation in films, and the prepared perovskite films exhibited enlarged grain size, increased light absorption, enhanced Br incorporation and prolonged carrier lifetime, which resulted in excellent photo-electrical properties of the CH3NH3PbBrXI3-X films. With porous PbI2 templates, the inverted planar perovskite solar cells based on films with appropriate Br incorporation (CH3NH3Br/CH3NH3I mole ratio = 3/7) showed a photovoltaic conversion efficiency (PCE) of 14.9%, and the stability of the devices in air was elevated. Consequently, the high-quality CH3NH3PbBrXI3-X films can be obtained with porous PbI2 templates for improving the performance of the perovskite solar cells.

In this study, MgNd intermetallic is deposited as a thin film using magnetron sputtering. Ultraviolet photoelectron spectroscopy (UPS) is employed to determine the work function of the MgNd thin film. It is found that the MgNd thin film has a low work function of 3.5 eV, leading to its application in hybrid poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS)/n-Si solar cells as a back surface field (BSF) material. By introducing a MgNd thin film into the back Si/electrode interface of a hybrid solar cell, obvious improvements in the open circuit voltage (Voc) and fill factor (FF) of the device are observed, leading to an increase by more than 26% in power conversion efficiency (PCE). Temperature-dependent current density–voltage (J-V) and Voc-light intensity measurements demonstrate that the introduction of a MgNd thin layer increases the built-in voltage at the rear interface and decreases the recombination current in the device. These improvements are attributed to the efficacy of the MgNd thin film as a BSF by reducing minority carrier recombination and enhancing majority carrier transport.

Perovskite solar cells (PSCs) have recently demonstrated high efficiencies of over 23%, but the stability is still a major challenge for commercialization. Here, we demonstrate that the decomposition of organometal halide perovskite and the corrosion of silver electrode caused by the participation of water in the prepared inverted triple cation PSCs is an important factor for cell performance degradation. Through deeply analyzing the degradation mechanism, it is found that moisture ingress and diffusion of halide ions are the main reasons for the metal-contact-induced degradation process. In order to suppress the degradation, we find that inserting a pinhole-free ultrathin TiO2 layer grown by atomic layer deposition between the electrode and absorber layer is an effective strategy, which can significantly improve the environmental stability of the PSCs.

In this paper, the CH3NH3PbBrXI3-X films were prepared by introducing CH3NH3Br into CH3NH3I precursor solution, after which the microstructure and photoelectric properties of the films were thoroughly investigated. Due to Br incorporation in the perovskite films, the band gap increased and the light absorption was slightly reduced while the charge carrier lifetime was prolonged due to the enhanced crystallinity. For the films with higher bromine content, the red shift of the photoluminescence peaks indicated that the phase segregation appeared in the films under illumination, which led to the formation of the iodine-rich domains in this process and the reduced carrier lifetime. On the contrary, for films with lower bromine content, the red shift of the photoluminescence peaks was negligible, which revealed that instability of the perovskite films under illumination can be suppressed by adjusting the bromine content of the films. Consequently, by moderate Br incorporation (CH3NH3Br/CH3NH3I mole ratio = 3:7), the CH3NH3PbBrXI3-X films with optimal photoelectric properties and photo-stability were achieved, and the stable photoelectric conversion efficiency of corresponding device under illumination can reach 13.8%.

The Si-QDs/SiO2 multilayer films with phosphorus (P) doping have been prepared, and carrier multiplication effect of the films with and without P doping was investigated by relative quantum yield of photoluminescence (PL). The relative quantum yield of PL shows a step like increase when the excitation energy is larger than 2 E g of Si-QDs, and the carrier multiplication is caused by space-separated quantum cutting in adjacent QDs. The PL peak shifts toward high energy region after P-doping, and the PL intensity is enhanced, however, the threshold energy for carrier multiplication is decreased from 2.97 to 2.89 eV. The results suggest that non-radiative recombination at the surface of Si-QDs is suppressed by P passivation, and radiative recombination from conduction band to surface defect level is possible. Energy transfer from hot electron-hole pair to surface defect level leads to the optical excitation of defect level, which generates an extra electron-hole pair, and carrier multiplication effect is observed in the P-doped multilayer film with lower excitation energy.

The experimental study of hydrogen-air detonation was performed in a 6.3-m-long circular cross-section tube, the rear section of which was walled by silicone or aerogel material. Mixtures of 25% or 29.6% hydrogen with air by volume with an initial pressure of 0.1 MPa and temperature of 293 K were used in the experiments. A short Shchelkin spiral was fixed at the tube head to accelerate the deflagration-to-detonation transition. The flame and pressure wave propagation velocities were measured by ion probes and pressure transducers, respectively. The detonation regimes and velocities of flame propagation in walled tubes of different materials were compared. It was found that it is difficult for a silicone rubber-walled tube to reduce the intensity of the detonation wave. In this case, for the stoichiometric mixture, a reduction in the propagation velocity by 5% and the pressure peak by 12% was recorded in order to compare those parameters in a stainless smooth tube. An aerogel blanket wall has a strong ability to reduce the intensity of the detonation wave with the peak pressure decreased by 35% for the stoichiometric hydrogen-air mixture. The attenuation of the steady detonation wave can occur in the aerogel blanket-walled tube under the present experimental conditions. This is because of the effective suppression of transverse waves by interaction with the aerogel wall; then, the generation of stable detonation cells is no longer possible, and thus, the shock wave and flame front are decoupled, and detonation is suppressed.

A high-speed droplet-laden reacting shear layer is modeled numerically to analyze the dynamics of flame kernel for better understanding ignition and extinction processes in spray combustion. The droplet-laden shear layer, separating a hot-air stream from a monodisperse spray-laden air stream, is modeled by the Eulerian-Lagrangian approach, in which the continuous phase is governed by the compressible Navier-Stokes equations together with species transport equations and the discrete droplets are tracked by the Lagrangian method. The convective flux terms of the conservative equations are solved by an adaptive central-upwind WENO scheme. Two-way coupling interactions consider exchanges of mass, momentum, and energy between the carrier-gas fluid and the liquid-fuel spray. The shear layer convective Mach number is specified as 0.4 in the present study, and hence, large scales of motion dominate both the fluid mixing and the droplet dispersion. The preferential concentration of droplets is observed. Auto-ignition kernels occur in the high-strain regions where sufficient fuel vapors distribute near the hot stream-boundary. The incipient chemical reaction consumes the available fuel vapors through a diffusion flame combined with a thin premixed flame, as a lean deflagration propagates across the mixing layer towards the spray. The present results unveil two different types of extinction behavior depending on the local strain rate and the available fuel for the reaction kernel. The latter type of extinction originates when the separated flame kernel is entrained into the core of an adjacent vortex but droplets cannot be entrained in the eddies to produce gaseous fuels for the chemical reaction due to the preferential segregation effect. The dynamics of ignition and extinction in the shear flows depend on the droplet dispersion, the droplet evaporation rate and the diffusion of fuel vapor.