Search

Thermoelectric (TE) performance of polycrystalline stannous selenide (SnSe) has been remarkably promoted by the strategies of energy band, defect engineering, etc. However, due to the intrinsic insufficiencies of phonon scattering and carrier concentration, it is hard to simultaneously realize the regulations of electrical and thermal transport properties by one simple approach. Herein, we develop Cu and Ce co-doping strategy that can not only greatly reduce lattice thermal conductivity but also improve the electrical transport properties. In this strategy, the incorporated Cu and Ce atoms could induce high-density SnSe2 nanoprecipitation arrays on the surface of SnSe microplate, and produce dopant atom point defects and dislocations in its interior, which form multi-scale phonon scattering synergy, thereby presenting an ultralow thermal conductivity of 0.275 W·m-1·K-1 at 786 K. Meanwhile, density functional theory (DFT) calculations, carrier concentration, and mobility testing reveal that more extra hole carriers and lower conducting carrier scattering generate after Cu and Ce co-doping, thereby improving the electrical conductivity. The co-doped Sn0.98Cu0.01Ce0.01Se bulk exhibits an excellent ZT value up to ~1.2 at 786 K and a high average ZT value of 0.67 from 300 to 786 K. This work provides a simple and convenient strategy of enhancing the TE performance of polycrystalline SnSe.

Molybdenum trioxide (MoO3) is regarded as a promising electrode material for lithium (Li)-ion batteries because of its unique layered structure with a high theoretical capacity (~ 1117 mAh·g−1). Till now, numerous researches have focused on tuning MoO3 morphology to improve its electrochemical performance. However, the fabrication of MoO3 with a two-dimensional (2D) nanosheet clusters structure has yet been achieved. Here, we report a facile one-step solvothermal method to prepare MoO3 nanosheets, of which the morphology can be facilely tuned via the dose of hydrogen peroxide. Both the experimental results and theoretical calculation suggest that the resultant 2D nanosheets structure could reduce the diffusion paths, which is beneficial for the intercalation of Li-ion. As a result, the nanosheets assembled Li-ion battery has a reversible specific capacity of 756.1 mAh·g−1 at 0.5 A·g−1, and maintained at 214.7 mAh·g−1 after 600 cycles at a current density of 1 A·g−1 with the Coulombic efficiency as high as 97.17%.

Suppose 0

Self-reinforced lithium disilicate (Li2Si2O5, LD) glass-ceramics were hot pressing sintered by introducing 5 wt% Li2Si2O5 crystal seeds into two different glass compositions of SiO2-Li2O-P2O5-ZrO2-Al2O3-K2O-La2O3 (7C LD) and SiO2-Li2O-K2O-La2O3 (4C LD). The results show that the seeds play an important role in the crystallization inducement, and microstructural and property improvement of the glass, especially for the glass powder without the nucleating agent of P2O5. The microstructure features a wider bimodal grain size distribution with large rod-like crystals epitaxially grown along the seeds and small crystals nucleated from the glass powder itself, contributing to the improvement of the performance especially the fracture toughness. The specimen of 4C LD glass with the addition of 5 wt% Li2Si2O5 seeds exhibited the best comprehensive properties with a good flexural strength (396±7 MPa), improved fracture toughness (3.31±0.19 MPa·m1/2), and comparable translucency as IPS e.max. This research provides a new idea and method for the improvement of the fracture toughness of lithium disilicate glass-ceramics without affecting its aesthetic appearance, and lays the foundation for its clinical applications.

In this paper, lattice Boltzmann simulation for unsteady shock wave/boundary layer interaction in a shock tube is presented. This kind of problem, which contains the typical characteristics of supersonic viscous flows with shock wave and boundary layer, has rarely been well validated in the lattice Boltzmann community. This leads to few application of lattice Boltzmann method in supersonic flows with boundary layer. Some problems related to numerical dissipation and stability are exposed when simulating shock wave/boundary layer interaction using the conventional compressible lattice Boltzmann approach. The implementations of lattice Boltzmann for this kind of flow are investigated. As a novel problem for the lattice Boltzmann method, three main issues need to be addressed carefully, i.e., lattice Boltzmann model, solving scheme, and boundary treatment. For the first issue, a double-distribution-function compressible lattice Boltzmann model, in which the lattice velocity is studied for the stability in the simulation, is employed since we have demonstrated its feasibility in supersonic viscous flow previously. For the solving scheme, various space discretization methods are tested to enhance numerical performance. Meanwhile, the boundary treatment for the ghost layer is studied. The simulation result by the improved lattice Boltzmann implementation agrees well with the results through Navier–Stokes equations and gas-kinetic scheme reported in previous literatures. This work probes the numerical implementations of lattice Boltzmann method for unsteady shock wave/boundary layer interaction, providing important theoretical support for lattice Boltzmann application in supersonic viscous flows with shock wave and boundary layer.

We establish a boundary Schwarz lemma for solutions to nonhomogeneous biharmonic equations.

For g ∈ C ( D ‾ ) , φ ∈ C ( T ) and f ⁎ ∈ C ( T ) , let BH φ , g , f ⁎ ( D ) be the class of all complex-valued functions f ∈ C 4 ( D ) satisfying Δ ( Δ f ) = g in the unit disk D with Δ f = φ in the unit circle T and f = f ⁎ in T , where Δf is the Laplacian of f. In this article, we will show that several Schwarz type lemmas for f ∈ BH φ , g , f ⁎ ( D ) , and, by applying these results, we will establish a Landau type theorem on a subclass of BH φ , g , f ⁎ ( D ) .

In this study, a constitutive model is developed in order to investigate wave–seabed interactions. This model takes into account the impact of principal stress rotation (PSR) and is based on the generalized plasticity theory, in which plastic strain generated by PSR is considered an additional item in the constitutive relationship of soil. The normalized loading direction and plastic flow direction were determined based on the stress tensor invariant. Comparisons between the present model and previous Hollow Cylinder Apparatus tests and geotechnical centrifugal wave tests show good agreement. Numerical results show the effects of PSR on predictions of liquefaction potential due to: (a) the cumulative impact of plastic strain in the seafloor and (b) the buildup of pore pressure. Parametric study shows that the model parameters, including the wave and seabed parameters, have significant effects on the wave-induced soil liquefaction.

This paper presents a simple but workable constitutive model for the stress–strain relationship of sandy soil during the process of tunneling construction disturbance in coastal cities. The model was developed by linking the parameter K and internal angle φ of the Duncan–Chang model with the disturbed degree of sand, in which the effects of the initial void ratio on the strength deformation property of sands are considered using a unified disturbance function based on disturbed state concept theory. Three cases were analyzed to investigate the validity of the proposed constitutive model considering disturbance. After validation, the proposed constitutive model was further incorporated into a 3D finite element framework to predict the soil deformation caused by shield construction. It was found that the simulated results agreed well with the analytical solution, indicating that the developed numerical model with proposed constitutive relationship is capable of characterizing the mechanical properties of sand under tunneling construction disturbance.

Suppose $p\geq1$, $w=P[F]$ is a harmonic mapping of the unit disk $\mathbb{D}$ satisfying $F$ is absolutely continuous and $\dot{F}\in L^p(0, 2��)$, where $\dot{F}(e^{it})=\frac{\mathrm{d}}{\mathrm{d}t}F(e^{it})$. In this paper, we obtain Bergman norm estimates of the partial derivatives for $w$, i.e., $\|w_z\|_{L^p}$ and $\|\overline{w_{\bar{z}}}\|_{L^p}$, where $1\leq p, 17 pages

In the present study, we analyze the epidemic trend and characteristics of pulmonary tuberculosis (PTB) registered in the Jiading Industrial Zone, Shanghai from 2010 to 2017, and the information concerning delays in visit to hospital, diagnosis, and treatment. The most important purpose was to reveal the difference in PTB characteristics between local population and migrants. Tuberculosis epidemic data were collected from the National Information System for Disease Control and Prevention (NISDCP) and the specific Jiading system for tuberculosis patients between 2010 and 2017. Descriptive statistics were produced for the epidemic trend and characteristics of PTB cases. The epidemic trend of PTB for migrants was different from the trend for the local population. The peak months for the presentation of migrant TB cases were July, September, and April. The peak months for the presentation of local TB cases were November, July, and April. The two age groups with the greatest percentage of migrant TB cases were 25–34 years and 15–24 years, and the two age groups for the local TB cases with the greatest percentage were ≥ 65 years and 45–54 years. A certain proportion of patients had a delay in visit to hospital (41.00%), delay in diagnosis (26.04%), and delay in treatment (1.38%). Shanghai is a domestic immigration city; a tuberculosis epidemic cannot be ignored. In the current study, local population and migrants have different epidemiological characteristics of tuberculosis. Therefore, different strategies and measures should be adopted for local populations and migrants. In addition, publicity and education concerning early detection and early treatment should be strengthened.

To solve the problem of low disassembly efficiency of complex products, an asynchronous parallel disassembly sequence planning method of multi-manipulator based on improved shuffled frog leaping algorithm was proposed. Depending on the characteristics of this method, the disassembly manipulators are taken as the research object, and the minimum completion time of disassembly is taken as the optimization objective. Based on the basic disassembly time of parts, the disassembly preparation time caused by the change of disassembly tools and directions is considered, so that the objective function evaluation model is more realistic. Then, the mathematical model of asynchronous parallel disassembly sequence planning is constructed and the disassembly information modeling method is optimized. We proposed a new method based on the fastener constraint matrix and the part constraint matrix to build the information model of product disassembly. Based on this model, the detachable conditions are derived and the feasible disassembly sequence is obtained. In order to improve the performance of the proposed algorithm, a double-link encoding method and an efficient decoding operator is proposed. The adjustment orders which based on adjustment position and the substitution formulas are constructed to carry out the new segmental local evolution of frog individuals, and the update formula of frog position is reconstructed. Furthermore, the two-point mutation operator is added to the global information exchange strategy to enhance the search ability of the algorithm. The proposed algorithm is applied to a screw lifting mechanism and four products of varying complexity, and the results are compared with two algorithms. The results show that the proposed method can solve disassembly problems of different scales and is especially effective in solving large-scale disassembly problems.

The buzz phenomenon of a typical supersonic inlet is analyzed on the basis of numerical simulations and duct acoustic theory. Considering that the choked inlet could be treated as a duct with one end closed, a one-dimensional (1D) mathematical model based on the duct acoustic theory is proposed to describe the periodic pressure oscillation of the little buzz and the big buzz. The results of the acoustic model agree well with that of the numerical simulations and the experimental data. It could verify that the dominated oscillation patterns of the little buzz and the big buzz are closely related to the first and second resonant mode of the standing wave, respectively. The discrepancies between the numerical simulation and the ideal acoustic model might be attributed to the viscous damping in the fluid oscillation system. In order to explore the damping, a small perturbation jet is introduced to trigger the resonance of the buzz system and the nonlinear amplification effect of resonance might be helpful to estimate the damping. Through the comparison between the linear acoustic model and the nonlinear simulation, the calculated pressure oscillation damping of the little buzz and the big buzz are 0.33 and 0.16, which could be regarded as an estimation of real damping.

We study the Schwarz lemma for harmonic mappings in general setting and prove among the other results that: if H(Q,M) is the class of harmonic mappings f of the unit disk U into the geodesic disk D...

Let D ‾ be the closure of the unit disk D in C and g a continuous function of D ‾ . In this paper, we establish the Schwarz lemma at the boundary for solutions to the Poisson's equation: △ f = g .

A better understanding of physical process of the fluid-seabed-structure interaction (FSSI) is beneficial for engineers involved in the design of marine infrastructures. Most previous studies for the problem of FSSI have considered wave-only conditions, despite the co-existence of wave and current in the real ocean environment. Unlike the previous studies, currents are included in the present study for the numerical modelling of FSSI, using an integrated FVM-FEM scheme, in which the VARANS equation is used to simulate fluid field, while Biot's poro-elastic model is used for porous flow in a seabed. Numerical examples show the important influences of currents on the local hydrodynamic process and the resulting dynamics of seabed foundation around a submerged rubble mound breakwater. The structure is relatively stable in the presence of counter-current waves, whereas the co-current waves would significantly compromise the instability of structure due to potential of shear failure and liquefaction in its sandy seabed foundation.

In this paper, we first improve the boundary Schwarz lemma for holomorphic self-mappings of the unit ball Bn, and then we establish the boundary Schwarz lemma for harmonic self-mappings of the unit disk D and pluriharmonic self-mappings of Bn. The results are sharp and coincides with the classical boundary Schwarz lemma when n = 1.

Evaluation of wave-induced soil response is particularly important for coastal geotechnical engineers involved in the foundation design for marine structures such as immersed tunnels, breakwaters, platforms etc. In this study, a finite element model for the wave-induced soil response around an immersed tunnel is developed, in which the seabed is treated as a porous medium and characterized by Biot's consolidation equations, while the tunnel is considered as a single-phase medium and behaves under a linear elastic law. A new conceptual pore-pressure buildup model is developed to investigate the wave-induced residual liquefaction around the tunnel due to the accumulation of pore pressures under cyclic shearing. The consolidation analysis of seabed foundation under the gravitational forces including the body forces of the structure is pre-assessed and incorporated. It is demonstrated from numerical results that the development of residual pore pressure is asymmetric in nature around the tunnel, which may result in the uneven liquefaction depth and deformation in the seabed near the bottom of the tunnel, thus compromising the stability of the structure. Parametric studies show that wave-induced residual liquefaction is more likely to occur in the shallow seabed with lower relative density and permeability under the wave loading with higher wave height and longer period.

Denote by C α ( D ) the space of the functions f on the unit disk D which are Holder continuous with the exponent α, and denote by C 1 , α ( D ) the space which consists of differentiable functions f such that their derivatives are in the space C α ( D ) . Let C be the Cauchy transform of Dirichlet problem. In this paper, we obtain the norm estimates of ‖ C ‖ L p → L q , where 3 / 2 p 2 and q = p / ( p − 1 ) . Suppose g ∈ L p ( D ) and f = G [ g ] is the Green potential of g. By using Sobolev embedding theorem, we show that if 1 p ≤ 2 , then f ∈ C μ ( D ) , where μ = 2 − 2 / p . We also show that if 2 p ∞ , then f ∈ C 1 , ν ( D ) , where ν = 1 − 2 / p . Finally, for the case p = ∞ , we show that f is not necessarily in C 1 , 1 ( D ) , but its gradient, i.e., | ∇ f | is Lipschitz continuous with respect to the pseudo-hyperbolic metric. This paper is inspired by [2, Chapter 4] and [9] .

Recently, behavior of large-diameter mono-pile foundations for offshore wind turbines under long-term cyclic wave loading has attracted great attentions from coastal engineers. In this study, a three-dimensional integrated numerical model is developed to investigate the wave-induced seabed response around a monopile foundation. In the model, the Reynolds-Averaged Navier-Stokes (RANS) equations are used for the mean fluid flow, while the Biots consolidation equations are used for the solid-pore fluid interaction in a porous seabed. The monopile is considered as a single phase medium and behaves under a linear elastic law. To reproduce the residual soil behavior under cyclic shearing induced by ocean waves as well as structural rocking motions, a poro-elastoplastic model is adopted, in which the consolidation analysis of seabed foundation under gravitational forces including the body force of structure is pre-assessed and incorporated. The present numerical framework was first validated against several laboratory experiments and obtaining fairly good agreements. Based on the proposed model, failure of monopile foundation caused by liquefaction due to the buildup of pore water pressure under cyclic shearing is investigated. Numerical results indicate that the potential areas for residual pore pressure development and the resulting liquefaction are most pronounced in the vicinity of the monopile following the wave propagation direction, which is caused by waves as well as the rocking motion of the structure induced by the wave impact. Parametric studies indicate that there is no possibility of generating soil liquefaction below the pile bottom in the vicinity of the mono-pile even under large waves.

In this study, an integrated model is developed to investigate the potential risk for failure of caisson-type breakwaters caused by liquefaction in its loosely deposited sand foundations. In the present model, the Volume-Averaged Reynolds Averaged Navier-Stokes (VARANS) equations are used for solving flow inside and outside the porous media, while Biot's consolidation equation is used for linking the soil skeleton-pore fluids interactions. A new developed poro-elastoplastic model is implemented to reproduce the behavior of loose sand foundation under cyclic shearing. Verification of the present numerical framework includes (i) comparison with the laboratory experiments in terms of water surface levels around the structure, and the fluctuating component of the pore water pressure inside the rubble mound and seabed foundation; and (ii) comparison with the geotechnical centrifugal wave tests for the wave-induced residual component of pore water pressures in a porous seabed. Based on the present model, the hydrodynamic process and the associated dynamic foundation behavior involved in the interactions between the ocean waves, a composite breakwater and its loose sand foundations was performed and analyzed. Particular focus is put on the residual pore pressure development and the resulting liquefaction around the structure under combined actions of both wave and structure rocking motions. Based on the numerical examples presented, under combined actions of both wave and caisson motions, liquefaction starts on both edges of the breakwater and spreads sideways until reaching an equilibrium state where the maximum liquefaction depth can be observed. The liquefied zone around the breakwater is asymmetric in nature, and the maximum depth of soil liquefaction appears at the seaward side of the structure. Furthermore, the parametric study indicates that the maximum liquefaction depth around the composite breakwater increases with increasing wave steepness (H/L0) and relative water depth (d/L0) and decreasing soil permeability (ks).

In the analysis of the interaction between external periodic excitation and unsteady separated flow in controlling the flow separation, a new nonlinear approximate model has been established. This model is used to describe the typical chaotic and coherent characteristics of a separated flow such as small- or large-scale vortices, the injection, and the dissipation of the kinetic energy based on a simulation of a simplified cross-direction motion of free shear flows. This study presents an appropriate treatment to simulate the external periodic excitation and uses the maximum Lyapunov exponent to evaluate the degree of flow ordering in the different control states. The results of the nonlinear model are compared with experimental and numerical results, showing that the nonlinear model could be used to effectively explain the behaviours of chaotic flows and investigate the rules for controlling separated flows. In addition, as shown in the nonlinear approximate model, the self-synchronization of unsteady flow separation and periodic excitation has been analysed. Initially, the research provided an explanation of the self-synchronization mechanism, which cites that the effects of the separated flow control are independent of the phase difference between the periodic excitation and the unsteady flow. The characteristics of unsteady separated flow control have also been presented in this model, where the corresponding large eddy simulation (LES) was used for separated flows in a curved diffuser. The proper orthogonal decomposition (POD) method was used to analyse the difference between separated vortical structures with or without periodic excitation. The results showed that the model and the simulation had the same mechanism of flow control as for the separated flows. The periodic excitation transforms the original chaotic flow into a relatively ordered flow and decreases the magnitude of the chaotic unstable vortices, rather than completely eliminating the vortices, while flow mixing is reduced, inducing less energy loss.

The buzz phenomenon of a typical supersonic inlet is analyzed using the unsteady Reynolds Average Navier-Stokes (RANS) simulation and proper orthogonal decomposition (POD) method. The dominant flow patterns and characteristics of the buzzed flow are obtained by decoupling the computed pressure field into spatial and temporal sub-parts based on the POD method. The supersonic inlet buzz phenomenon could be approximated as a product of decoupled temporal and spatial terms, and the one-dimensional (1D) mathematical model is therefore proposed. The standard deviations of the unsteady pressure fields from both the numerical simulation and the model prediction are compared. The limited discrepancy can be observed, and the good agreement validates the credibility of the proposed 1D model. The numerical simulation and the 1D model prediction are presented to explore the unsteady-jet control with a small perturbation. The results of the 1D model and the numerical simulation achieve good agreements with each other in terms of the overall trend. Finally, POD modal energy is employed to analyze the buzz suppression mechanism. When the jet frequency is identical to the dominant frequency of the buzz and the jet phase is opposite to the oscillation phase of the captured mass flow, the buzz suppression could be more efficient. The buzz suppression mechanism could be explained in two aspects. For one thing, the complex flow structure is suppressed and the first average modal energy in the inlet is increased. For another, the energy redistribution among each POD mode is achieved and the flow stability is gradually enhanced.

Suppose $w$ is a sense-preserving harmonic mapping of the unit disk $\mathbb{D}$ such that $w(\mathbb{D})\subseteq\mathbb{D}$ and $w$ has a zero of order $p\geq1$ at $z=0$. In this paper, we first improve the Schwarz lemma for $w$, and then, we establish its boundary Schwarz lemma. Moreover, by using the automorphism of $\mathbb{D}$, we further generalize this result., Comment: 10 pages; To appear in Bulletin of the Malaysian Mathematical Sciences Society

We estimate the Jacobian of harmonic mapping of the unit disk onto a smooth and convex Jordan domain via the boundary function and the boundary curvature of the image domain. By using this result we make some asymptotically sharp estimates of constant of quasiconformality for harmonic diffeomorphisms between the unit disk and the convex domains via their boundary mappings.

In this paper, a modified graphical approach is presented for targeting the water-using networks of single contaminant involving regeneration. Two situations are studied in this paper: the regenerated concentration is lower than the lowest limiting inlet concentration (except 0 ppm), and the regenerated concentration is higher than the lowest limiting inlet concentration (except 0 ppm). The latter situation has not been investigated with the graphical methods in the literature. The parameters of the water networks, including Regeneration Pinch, the targets of freshwater, and regenerated water, can be obtained by the proposed graphical approach. Both the Fixed Contaminant Load and Fixed Flow Rate systems are discussed. A few examples are investigated to show the targeting procedure.

Suppose $f\in L^p(\mathbb{D})$, where $p\geq1$ and $\mathbb{D}$ is the unit disk. Let $\mathfrak{J}_0$ be the integral operator defined as follows: $\mathfrak{J}_0[f](z)=\int_{\mathbb{D}}\frac{z}{1-\bar{w}z}f(w)\mathrm{d}A(w)$, where $z$, $w\in\mathbb{D}$ and $\mathrm{d}A(w)=\frac{1}{\pi}\mathrm{d}x\mathrm{d}y$ is the normalized area measure on $\mathbb{D}$. Suppose $\mathfrak{J}_0^*$ is the adjoint operator of $\mathfrak{J}_0$. Then $\mathfrak{J}^*_0=\mathfrak{B}\mathfrak{C}$, where $\mathfrak{B}$ and $\mathfrak{C}$ are the operators induced by the Bergman projection and Cauchy transform, respectively. In this paper, we obtain the $L^1$, $L^2$ and $L^{\infty}$ norm of the operator $\mathfrak{J}_0^*$. Moreover, we obtain the $L^p(\mathbb{D})\rightarrow L^\infty(\mathbb{D})$ norm of the operators $\mathfrak{C}$ and $\mathfrak{J}_0^*$, provided that $p>2$. This study is a continuation of the investigations carried out in [4] and [11]., Comment: 20 pages

Low-crested structures such as submerged rubble mound breakwaters (RMB) are commonly used as successful examples of coastal protection measures. This study addresses foundation issues related to the performance of a submerged RMB constructed on a liquefiable site where the foundation soils have been loosely deposited; these issues were investigated using an integrated numerical model proposed by Zhao et al. (2018). Unlike previous work in Zhao et al. (2018), the dynamic features of loose sand deposits (i.e. build-up of pore water pressures, development of plastic strains, degradation of soil stiffness) due to the fluid–seabed-structure interactions, accompanied by the onset of liquefaction, were simulated. The reliability of this model to predict the liquefaction susceptibility of loose sand deposits was validated against the experimental results available in literature. This study shows that the submerged RMB constructed on a liquefiable seabed experienced progressive and asymmetric downward settlement under successive loading cycles. The opposing currents in the wave field tended to enhance this asymmetric settlement whereas the following currents did the opposite. Regardless of changes to the magnitude and direction of current velocities, ignoring the currents in the wave field may lead to an overestimation of the increased rate of residual pore water pressures in the region underneath the breakwater, particularly in shallow soil layers where the maximum relative differences can reach up to 120% of ( p current − p no-current ) ∕ P 0 at t ∕ T =25.

The principal stresses that occur in soil below ground level often change direction due to engineering activities. A typical example would be the cyclic loading applied by waves and currents onto the foundation of offshore structures. Even though the principal stress rotations (PSR) are recognized as some kind of “loading” that is exerted onto seabed soil, it is ignored in most investigations into how soil around marine structures responds to ocean waves and currents. In response this paper will simulate the fluid-seabed-structure interactions (FSSI) while considering the impact of PSR. This simulation will utilize an integrated numerical model in which VARANS equations are used for the flow motion. A coupled fluid-dynamic framework and a generalized plasticity model will be developed for the saturated porous medium to examine the cyclic loading of seabed and the continuous rotation of principal stress orientations. It is predicted that the stress path in the τ x z versus ( σ x ′ − σ z ′ ) plane around the structure will denote variations in deviator stress in conjunction with the rotations of the principal stress axis. The mechanical impact of PSR becomes most significant in the region beneath the breakwater and up to a depth of the half thickness of the seabed. Ignoring the PSR-induced deformation may lead to an underestimation of ( p P S R − p n o − P S R ) ∕ γ w d by 35% in this region.

This study aims to address the fundamental mechanical behavior of soft clay stabilized by the composite of citric-acid-modified magnesium oxysulfate cement, silica fume, and clinker (CMMOSC-S-C composite) at different initial soil-water contents (w), amounts of stabilizing agent (Wg), and curing time (T). X-ray diffraction analysis and Scanning electron microscopy indicate that the main products of the curing reaction can be summarized as 5·1·7 phase, gel, dolomite, pyrophyllite, and minor amounts of CaO and MgO, which could be attributed to the hydration, carbonation, ion exchange, and filling. The unconfined compressive strength tests, one-dimensional consolidation tests and unconsolidated undrained triaxial compression tests show that the unconfined compressive strengths (qu), secant Young's modulus (E50), and shear strength parameters (c and φ) are positively dependent on Wg and T. However, these parameters demonstrate a negative relationship with w. The compression efficient (a2–4) is positively and negatively related to w, Wg, and T. In view of these test results, empirical relationships between the fundamental mechanical parameters of CMMOSC-S-C composite stabilized soft clay and key effect factors (w, Wg, T) are developed to predict the qu, E50, a2–4, c, and φ values at any w, Wg, and T.

An integrated analysis method for a rocket-augmented turbine-based combined cycle (TBCC) engine is proposed based on the trajectory optimization method of the Gauss pseudospectral. The efficiency and energy of the vehicles with and without the rocket are analyzed. Introducing an appropriate rocket to assist the TBCC-powered vehicle will reduce the total energy consumption of drag, and increase the vehicle efficiency in the transonic and the mode transition. It results in an increase in the total efficiency despite a reduction in engine efficiency. Therefore, introducing a rocket as the auxiliary power is not only a practical solution to enable flight over a wide-speed range when the TBCC is incapable but also probably an economical scheme when the the TBCC meets the requirements of thrust. When the vehicle drag is low, the rocket works for a short time and its optimal relative thrust is small. Thus, the TBCC combined with a booster rocket will be a more simple and suitable scheme. When the vehicle drag is high, the operating time of the rocket is long and the optimal relative thrust is large. The specific impulse has a significant impact on the flight time and the total fuel consumption. Accordingly, the combination form for the rocket-based combined cycle (RBCC) engines and the turbine will be more appropriate to obtain higher economic performance.

Laminated shafts are often used as alternatives to elemental metal shafts, which are prone to corrosion and wear. However, manufacturing laminated shafts is difficult. In this paper, a laminated shaft production method involving cross-wedge rolling was proposed. The cross-wedge rolling of 42CrMo/Q235 laminated shafts was numerically simulated using ANSYS/LS-DYNA software. The deformation characteristics and stress distribution laws of the 42CrMo/Q235 laminated shafts in the knifing zone and stretching zones were obtained. The formation mechanisms of the stress distributions were analyzed, and the theoretical significance of the interface bonding on the cross-wedge-rolled 42CrMo/Q235 laminated shafts was discussed. Furthermore, the feasibility of 42CrMo/Q235 laminated shaft production via cross-wedge rolling was validated. Theoretical foundations were also provided for use in future studies concerning the rolling lamination mechanisms of dissimilar-metal laminated shafts.

Let \(w=P[F]\) be a harmonic mapping of the unit disk \({\mathbb {D}}\) with the boundary function \(F\). By using Poisson formula, we obtain some better estimates on Bloch constants for planar harmonic mappings.

Al2O3/TiAl composites were successfully fabricated from powder mixtures of Ti, Al, TiO2, Cr2O3 and Nb2O5 by a hot-press-assisted exothermic dispersion method. The effect of the Cr2O3 and Nb2O5 addition on the microstructures and mechanical properties of Al2O3/TiAl composites was characterized. The results showed that the specimens are mainly composed of TiAl, Ti3Al, Al2O3, NbAl3 and Cr2Al. The Vicker-hardness and density of Al2O3/TiAl composites increase gradually with the increase of Nb2O5 content. When the Nb2O5 content was 6.54 wt %, the flexural strength and fracture toughness of the composites have a maximum values of 789.79 MPa and 9.69 MPa?m1/2, respectively. The improvement of mechanical properties is discussed in detail.

To control the flow separation in the compressors, a novel pulsed jet concept without external energy injection is proposed. The new concept designs a slot in the middle of the blade and sets a micro device to switch the slot periodically. Such a structure is expected to generate a pulsed jet by the pressure difference between the pressure side and the suction side of the blade. In order to analyze the interaction between the pulsed jet and unsteady separated flow, our numerical and experimental study is based on a specific cascade (with a flow separation inside) and a pulsed jet (one of the unsteady flow control method). The experimental and numerical results both show that when the frequency of pulsed jet is approximate to that of the separation vortex, then the control tends to be more effective. Based on the numerical simulations, the proper orthogonal decomposition (POD) is then used to reveal the control mechanism, extracting the different time-space structures from the original field. The results with the aid of POD show that the pulsed jet can redistribute the kinetic energy of each mode, and strengthen or weaken certain modes, particularly, while the steady jet reduces the kinetic energy of high-order modes in whole. Also, pulsed jet with proper parameters can transfer the energy from higher modes to the first flow mode (averaged flow), which is due to the conversion of the spatial vortical structures and the time evolution of the modes.

Two three-dimensional (3D) lattice Boltzmann models in the framework of coupled double-distribution-function approach for compressible flows, in which specific-heat ratio and Prandtl number can be adjustable, are developed in this paper. The main differences between the two models are discrete equilibrium density and total energy distribution function. One is the D3Q25 model obtained from spherical function, and the other is the D3Q27 standard lattice model obtained from Hermite expansions of the corresponding continuous equilibrium distribution functions. The two models are tested by numerical simulations of some typical compressible flows, and their numerical stability and precision are also analysed. The results indicate that the two models are capable for supersonic flows, while the one from Hermite expansions is not suitable for compressible flows with shock waves.

Principal stress rotation (PSR) is one of the main stress conditions for a soil element subject to cyclic waves. It is one of the main causes behind generation of excess pore water pressure and cumulative plastic strain in soil deposits when drainage conditions are impeded, and thus compromises the stability of any supported marine structures. This paper aims to investigate the influence of PSR on the cyclic characteristics of soil under standing waves that are partially reflected, in which a generalized plasticity model considering the effect of PSR was adopted to model the soil behavior. Comparisons between the present model, previous hollow cylinder apparatus tests, and geotechnical centrifugal wave tests all show good agreement. Numerical results indicate that ignoring the PSR involved in the standing-wave–seabed interactions will significantly underestimate the build-up of pore water pressure, particularly at the standing wave nodes. Furthermore, the exclusion of the effect of PSR may lead to contradictory results in terms of susceptibility to liquefaction between the antinode and the node, when compared to the wave flume test and geotechnical centrifuge test. Numerical simulation results also demonstrate that while considering the impact of PSR, a sandy seabed exhibits higher liquefaction resistance when subjected to standing waves compared to the case when subjected to progressive waves with an equivalent wave height. Parametric studies show that the coefficient of wave reflection, wave characteristics (wave height, period, and water depth), and soil properties (permeability and saturation) significantly affect the liquefaction characteristics of soil under partially reflected standing waves.

This paper presents a new method of braking control related to the brushless DC Motor control industrial sewing machine system by analyzing the braking method of brushless DC Motor and the characteristics of control method concerning industrial sewing machines system. With the RENESAS SH7125 MCU as the core controlling, this paper analyzes from the both aspects of speed regulation and braking control, adopts oscillating circuit frequency input method for frequency control, reversing locking brake by detecting needle position signal. Practice proves that the method has achieved good effect, met the control requirements of the industrial sewing machine system.