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This paper proposes an analytical solution for the calculation of vibrations from a twin tunnel embedded in a half-space to assess the influence of a neighbouring tunnel on the ground-borne vibrations due to underground railway traffic. Using the wave function method, the total wave field in a half-space containing two cavities is expanded as the combination of down-going plane waves from the free surface and outgoing cylindrical waves from each cavity. The two tunnels are modelled as hollow cylinders, and the wave field inside them can be represented as the superposition of outgoing and regular cylindrical waves. To solve this multiple scattering problem, three sets of coordinate system defined at the scattering surfaces are used to describe the cylindrical waves in polar coordinates and the plane waves in rectangular coordinates. The application of transformation and translation properties between plane and cylindrical waves makes it possible to represent the waves emanating from one scattering surface in terms of the coordinates defined at the other two surfaces. The boundary conditions at the free surface and two tunnels can then be applied to solve for the expansion coefficients for the vector wave functions of plane and cylindrical waves. The present approach is also valid for a multi-layered ground, and in the layer with the tunnels, the field is composed of outgoing waves from the tunnels, down-going waves from the upper interface of the layer and up-going waves from the lower interface. Numerical results show that there is one critical velocity around shear wave speed of soils for a single/twin tunnel in a homogeneous half-space. For a multi-layered geometry, two global critical velocities may exist for the twin tunnel case, and they are determined by the properties of the soil layer where the twin tunnel is located in and the layer below the tunnels.

H9N2 subtype avian influenza virus (AIV) has been persistently circulating in China. It causes huge economic losses to the poultry industry and poses a great threat to public health. Previously, we constructed a turkey herpesvirus live vector vaccine candidate strain expressing an H9 gene, HVT-H9. Results showed that immunisation with HVT-H9 could provide good immunity in specific pathogen free (SPF) chickens. In this study, field-bred Arbour Acres plus (AA+) broilers were additionally immunised with HVT-H9 at one day of age. Then, broilers were naturally infected with H9N2 AIV. During the endemic period, death occurred in flocks without HVT-H9 immunisation and the mortality rate increased rapidly, forming a clear death wave. However, HVT-H9 vaccination prevented broiler mortality. Etiological tests and serological tests showed that broilers were positive for H9N2 AIV. Collectively, HVT-H9 immunisation provided good immunity for broilers in the field by inhibiting H9N2 virus infection and transmission.

Jamming of particles is a phenomenon that occurs widely in our daily life and nature. However, the jamming of the polydispersed particle systems, such as sand particles, have rarely been studied and are not well understood. Thus, this work conducted CFD–DEM simulations to study the jamming of a polydispersed particle system with a log-normal particle size distribution. The simulation results show that the jamming probability is strongly dependent on the diameter of the larger particles in the distribution, especially the characteristic particle diameter d90. The orifice–particle size ratio, used to predict the jamming probability of the polydispersed particle system, can be defined as the ratio of the orifice size Do to d90. The prominent influence of large particles on jamming was illustrated from the view of the particle jamming arch compositions. Moreover, we found that the polydispersed particle jamming arch can form with the defect and avalanche under the fluid flow.

Domestic ducks are considered as the interface between wild aquatic birds and terrestrial poultry and play an important role in the transmission and evolution of avian influenza viruses (AIVs). However, the infectivity of H9N2 AIVs in different domestic duck species has not been systematically evaluated. Here we investigated the infectivity of various genotypes of chicken H9N2 AIVs in Pekin duck (Anas Platyrhynchos), Mallard duck (Anas Platyrhynchos) and Muscovy duck (Cairina Moschata) through intranasal inoculation. We found that Pekin ducks and Mallard ducks were generally resistant to chicken H9N2 virus infection, while Muscovy ducks were relatively susceptible to H9N2 AIVs. All the tested viruses were isolated from oropharynx, trachea and lung tissues of Muscovy ducks. Additionally, genotype 57 (G57) H9N2 AIVs, which was predominant in chickens since 2010, showed increased virus replication in this duck species, indicating an improved interspecies transmission ability of recent H9N2 viruses from chickens to ducks. Our results demonstrated the role of Muscovy ducks in the ecology of H9N2 AIVs. More attentions should be paid to this host during viral surveillances. Additionally, inactivated H9N2 vaccine may be unnecessarily used in Pekin and Mallard ducks.

H9N2 avian influenza viruses (AIVs) were prevailing in chickens, causing great economic losses and public health threats. In this study, turkey herpesviruses (HVT) was cloned as an infectious bacterial artificial chromosomes (BAC). Recombinant HVT (rHVT-H9) containing hemagglutinin (HA) gene from H9N2 virus were constructed via galactokinase (galK) selection and clustered regularly interspaced short palindromic repeats/associated 9 (CRISPR/Cas9) gene editing system. The recombinant rHVT-H9 showed no difference with parent HVT in plague morphology and virus replication kinetics. H9 protein expression of rHVT-H9 could be detected by western blot and indirect immunofluorescence assay (IFA) in vitro and in vivo. Immunization with rHVT-H9 could induce robust humoral and cellular immunity in chickens. In the challenge study, no chicken shed H9N2 virus from oropharynx and cloaca, and no H9N2 virus was found in viscera in vaccination groups. The result suggests that rHVT-H9 provides effective protection against H9N2 AIV in chickens.

High speed railway is an ever-expanding mega project in China, connecting more and more cities of economy importance. This paper presents a theoretical evaluation on vibrations of saturated ground induced by high speed train operating on an elevated bridge. The simply-supported bridge consisting of a slab railway track resting on multiple spans of box girder is treated using the periodic theory. While, the dynamic interaction between the piles and the ground halfspace is solved using the flexible volume method combing with thin layer element method developed by the authors for the saturated soil. Two characteristic frequencies of the superstructure that dominates the ground displacement response have been identified: one is the first natural frequency of girder beam with elastic bearings; the other is the first natural frequency of pier beam supported by the pile foundation.

Since the alarming settlement of transport infrastructures on soft subgrade caused by long-term traffic loading, a method for predicting settlement is of considerable significance in the engineering design. In this study, we proposed a practical and simple predicting method on the settlement of soft subgrade considering traffic loading effects. The model used in this method involves the principal stress rotation and loading frequency, which needs only four parameters with clear meaning obtained by several cyclic triaxial tests. The applicability of the model has been verified by previous results from other researchers. Moreover, the engineering practicality of this method was validated by the field data of a highway. The settlements under low-frequency and high-frequency are the upper limit and lower limit of the traffic load-induced settlements, respectively. With the increasing embankment thickness, the settlements decrease because the cyclic stress ratio decreases and the detrimental effect of the principal stress rotation on the settlement reduces. The vehicle load is a more influential factor in the settlement than the traffic volume.

The most commonly utilized inactivated influenza vaccines (IIVs) are usually deficient in cross immunity against divergent viruses. On the other hand, live attenuated influenza vaccines (LAIVs) are proved to be more effective in cross-protective immunity. We previously developed a H9N2 LAIV and verified its effective protection against a broad spectrum of H9N2 strains. In the present study, we evaluated its cross-immunity against H5N2 virus, a representative subtype of currently predominant H5 highly pathogenic avian influenza viruses. All chickens vaccinated with this LAIV survived from challenge of H5N2 virus in a lethal dose, and viral proliferation was effectively inhibited, as well as pathological lesions. Vaccination of this LAIV significantly activated H5N2-reactive CD4+ and CD8+ T cells in lungs. These LAIV-activated cross-reactive T cells expanded robustly following H5N2 exposure, and the increasing tendency was temporally correlated with viral clearance. Besides cellular immunity, factors of humoral immunity also play a contributing role in cross-immunity. Passively transferring H9N2 LAIV anti-serum resulted in 100% survival rate to chickens against H5N2 virus. Within components of the anti-serum, cross-binding IgGs against nucleoprotein (NP) of H5N2 virus were found of a contributing role in the cross immunity. These results indicate that this H9N2 LAIV represents a promising strategy for controlling highly pathogenic H5N2 virus in chickens. The cross immunity was partly attributed to LAIV activated H5N2-cross-reactive T cells and partly attributed to cross-binding IgGs against NP.

The equivalent stiffness of a saturated poroelastic halfspace that supports an infinite Euler-Bernoulli beam under a moving point load has been investigated in this paper. The smooth contact condition is assumed for the interface of beam and halfspace, however, with an improved continuity condition, i.e. the continuities of contact normal stress and contact vertical displacements are imposed across the width of the beam. The equivalent stiffness of the halfspace has been evaluated using a contour integration approach such that contributions of the Rayleigh pole and the dispersion branches can be explicitly taken into account. Influences of the continuity condition and the permeability on the equivalent stiffness have been studied. It is found that the imaginary part of the equivalent stiffness is nonzero since the viscous coupling between two phases of the saturated halfspace has been considered. This observation fundamentally differentiates the present paper to the work by Shi and Selvadurai (2016) where an infinite permeability has been assumed for the halfspace, i.e. null viscous coupling.

With the development of urbanisation, massive crushed demolished construction wastes (CDW) have been generated, leading to environmental and disposal problems. In order to recycle the waste efficiently, an engineering sustainable CDW disposal was carried in Dajiangdong area, Hangzhou China. CDW was used to stabilize the deposited loose silt for feasible constructions and liquefaction preventions. The mix comprised of silt, CDW and cement was designed to be used as subbase material with higher density and less void. The vibro-compaction was used to rearrange the grain distributions within the mixtures to improve the mechanical performance at an optimal constituent, and then the numerical simulation was performed to evaluate the internal mechanism of the admixture under compression. The result shows that the workability of CDW-silt-cement mixture has an optimum of CDW content at 50% in order to achieve the best engineering performance. Moreover, the cement, which intergrades the silt and supplies the cementation among the coarse CDW, are not only generate cohesion but also provide anti-erosion effect.

Vertical drains combined with vacuum pressure is widely used to accelerate soil consolidation in land reclamation, where the effective prediction of the consolidation behaviour is needed to decide the improvement plan. In this paper, analytical solutions are presented for the large-strain radial consolidation theory using three equivalent coefficients that reduce the order of the high nonlinear governing equation. The effectiveness of solutions is verified by comparing the predictions of them with finite element method (FEM) simulations in common ranges of all parameters. By simplifying the proposed solution, a practical design method is further presented to be utilized by practical engineers. The practical method's efficiency and accuracy are proved by comparing the calculated results based on two case histories with numerical simulations and the field measurements.

Soil settlement is one of the most common and critical issues in geologic and geotechnical engineering. Due to various sources of uncertainties, it is hard to predict soil settlement accurately. An inverse analysis using the information provided by field measurements is desirable for prediction with higher confidence. In this study, an inverse framework based on ensemble Kalman filtering (EnKF) is proposed to evaluate the soil settlement with quantified uncertainty. The theoretical and practical effectiveness of this scheme is demonstrated through synthetic and realistic tests to predict soil settlement of embankment roads. Inferred results including quantified uncertainties are obtained based on Bayesian theory, which makes a distinction between this method and conventional settlement prediction methods. The results of two synthetic tests show the parameters inferred by the EnKF converge to true values, which verify the satisfactory performance of the proposed scheme. A realistic application of Saga airport road is investigated, and the simulated settlement results are consistent with the field measurements. Moreover, Sobol method is adopted to study the sensitivity of model parameters, and detailed parameter studies are conducted to estimate the influence of ensemble size, the value range of prior distribution and observation error.

H9 subtype avian influenza virus (AIV) and infectious bronchitis virus (IBV) are major pathogens circulating in poultry and have resulted in great economic losses due to respiratory disease and reduced egg production. As similar symptoms are elicited by the two pathogens, it is difficult for their differential diagnosis. So far, no reverse transcription-polymerase chain reaction (RT-PCR) assay has been found to differentiate between H9 AIV and IBV in one reaction. Therefore, developing a sensitive and specific method is of importance to simultaneously detect and differentiate H9 AIV and IBV. In this study, a duplex RT-PCR (dRT-PCR) was established. Two primer sets target the hemagglutinin (HA) gene of H9 AIV and the nucleocapsid (N) gene of IBV, respectively. Specific PCR products were obtained from all tested H9 AIVs and IBVs belonging to the major clades circulating in China, but not from AIVs of other subtypes or other infectious avian viruses. The sensitivity of the dRT-PCR assay corresponding to H9 AIV, IBV and mixture of H9 AIV and IBV were at a concentration of 1×101, 1.5×101 and 1.5×101 50% egg infective doses (EID50) mL−1, respectively. The concordance rates between the dRT-PCR and virus isolation were 99.1 and 98.2%, respectively, for detection of samples from H9N2 AIV or IBV infected chickens, while the concordance rate was 99.1% for detection of samples from H9N2 AIV and IBV co-infected chickens. Thus, the dRT-PCR assay reported herein is specific and sensitive, and suitable for the differential diagnosis of clinical infections and surveillance of H9 AIVs and IBVs.

A railway viaduct model consisting of infinite spans of elastically-supported girders carrying a slab track of infinite length is established to investigate the influence of the slabs on the vertical dynamic response of the viaduct, when a moving harmonic point load or a moving sprung wheel is applied. The infinite rail, the discontinuous slabs and girders of identical span lengths are idealized as Euler–Bernoulli beams. The rail fasteners, the cushion layer beneath the slab and the elastic bearings at the girder supports are represented by discretely distributed springs of hysteretic damping. Due to the repetitive nature of the girders, the model can be divided into periodic three-beam units by the span length of the girder, and then solved analytically in the frequency domain using the property of periodic structure. Besides the first natural frequency of the girder with elastic bearings, it is found that the resonance frequency of the slab on the cushion layer has a significant influence on the dynamic response of the track and the girder. Parametric excitations due to the moving wheel periodically passing the discontinuous slabs contribute significantly to the wheel/rail interactions.

Swine influenza A virus (swine IAV) circulates worldwide in pigs and poses a serious public health threat, as evidenced by the 2009 H1N1 influenza pandemic. Among multiple subtypes/lineages of swine influenza A viruses, European avian-like (EA) H1N1 swine IAV has been dominant since 2005 in China and caused infections in humans in 2010. Highly sensitive and specific methods of detection are required to differentiate EA H1N1 swine IAVs from viruses belonging to other lineages and subtypes. In this study, a nested reverse transcription (RT)-PCR assay was developed to detect EA H1 swine IAVs. Two primer sets (outer and inner) were designed specifically to target the viral hemagglutinin genes. Specific PCR products were obtained from all tested EA H1N1 swine IAV isolates, but not from other lineages of H1 swine IAVs, other subtypes of swine IAVs, or other infectious swine viruses. The sensitivity of the nested RT-PCR was improved to 1 plaque forming unit (PFU) mL −1 which was over 10 4 PFU mL −1 for a previously established multiplex RT-PCR method. The nested RT-PCR results obtained from screening 365 clinical samples were consistent with those obtained using conventional virus isolation methods combined with sequencing. Thus, the nested RT-PCR assay reported herein is more sensitive and suitable for the diagnosis of clinical infections and surveillance of EA H1 swine IAVs in pigs and humans.

Influenza virus hemagglutinin (HA) plays an important role in viral antigenicity, replication and host range. However, few amino acid positions in HA were reported to play multiple functions in both viral antigenicity and replication. In the present study, through analyzing the amino acid sequences of H9N2 avian influenza viruses (AIVs) isolated from China, we identified a multi-functional substitution of D200N in HA1 protein. Firstly, the substitution of D200N changed the antigenicity of H9N2 AIVs. Secondly, the D200N increased the HA cleavage efficiency and reduced acid and thermal stability of HA protein, which triggered viral-endosomal membrane fusion whereby promoted the release of viral genome into the host cytoplasm. Finally, residue 200-N increased the replication of H9N2 viruses in both chicken embryo fibroblast (CEF) cells and chicken embryonated eggs. In summary, the D200N substitution is a newly identified antigenicity and replication determinant of H9N2 AIVs, which should be paid more attention during surveillance.

A truck–pavement–ground coupling model was established to study the dynamic responses of a saturated poroelastic half-space generated by a moving heavy truck on the uneven pavement. The ground was simulated as a fully saturated poroelastic half-space governed by Biot’s theory. The overlying pavement was simplified as a Kirchhoff thin plate. With the assumption of a sinusoidal pavement surface, the dynamic wheel–pavement force was obtained through a linear Hertizian contact model. The numerical results showed that this dynamic load could make considerable contributions to the stress and excess pore water pressure responses in the ground. Furthermore, the effective stress path of the soil unit beneath the pavement caused by the moving truck was firstly calculated and presented. It was found that the differences between the total stress path and the effective stress path became significant as the truck speed increased, thus the effective stress path was more suitable than total stress path to reflect the stress history of soil elements in the saturated ground during the passage of high-speed traffics.

Influenza viruses have been isolated from dogs in China; however, the extent of influenza infection among dogs is not yet clear. Here, we examined the seroprevalence of avian-origin canine H3N2, pandemic H1N1/09 and human seasonal H3N2 influenza viruses in pet dogs in China during January 2012 to June 2013. The seropositivity rate of canine H3N2, H1N1/09 and human H3N2 were 3.5%, 1.5%, and 1.2%, respectively. Dogs aged 2–5 years were most commonly seropositive to canine H3N2 virus. It is worth noting that two serum samples were positive against both canine H3N2 and H1N1/09 viruses, suggesting the possibility of coinfection with both viruses. Our findings emphasize the necessity for continued surveillance of influenza viruses in dogs in China.

Subgrade soils of traffic infrastructures are subjected to large numbers of load applications at a stress level below their shear strength. It is therefore of great practical relevance to study the deformation behavior of soft clay under long-term cyclic loading. In this study, a series of monotonic triaxial tests and long-term cyclic (50,000 cycles) triaxial tests have been carried out to investigate the undrained deformation behavior of undisturbed soft clay from Wenzhou, China. The stress–strain hysteretic loop, resilient modulus and permanent strain of the tested samples were found significantly dependent on CSR and confining pressure. With an increase of CSR and confining pressure, the resilient modulus decreases more significantly with increasing number of cycles and the accumulation rate of permanent strain increases. Furthermore, the shape of the stress–strain hysteretic loop almost remains unchanged and the resilient modulus tends to a steady value after a large number of cycles. Based on the experimental results, two equations are established for the prediction of long-term resilient modulus and permanent strain. Finally, a new critical value of 0.65 is suggested for CSR . When CSR >0.65, the resilient modulus for large number of cycles is reduced to a so called “asymptotic stiffness” and the accumulation rate of permanent strain significantly increases.

Biot’s theory has been widely employed to study responses of saturated soil under dynamic loads. To simplify the analysis, three simplified formulations based on Biot’s theory have been proposed, including the u–p formulation, fully undrained formulation and fully drained formulation. The u–p formulation is established by neglecting the relative pore fluid acceleration. The fully undrained formulation founds on the assumption of no relative pore fluid displacement. The fully drained formulation supposes an infinite soil permeability. Nevertheless, the successful applications of these simplified formulations are hindered because of their indefinite application scopes. To overcome this, this paper carries out a comparative study of the simplified formulations for modeling a saturated poroelastic half-space subjected to a moving harmonic point load. The three simplified formulations are investigated by comparing with Biot’s u–w formulation. A triple Fourier transform is first used to transform the four formulations into the frequency-wavenumber domain. Then an analytical inverse transform with respect to the frequency is performed to obtain the vertical soil displacement and pore pressure in the time-wavenumber domain. A parameter RΩ defined in the wavenumber domain, which integrates effects of the soil permeability, load oscillating frequency and moving load velocity, is proposed to determine the validity ranges of the three simplified formulations. Some critical values of RΩ are suggested and applied to a model in a previously published paper by Siddharthan et al.

Avian influenza viruses (AIVs) and Newcastle disease viruses (NDVs) co-circulate in the poultry population in China. These viruses cause repeated disease outbreaks that exhibit similar clinical symptoms and epidemiological patterns. H5 and H9 influenza viruses are the major pathogens infecting poultry stocks. Recently, H3 AIV (one of the main subtypes in waterfowl) has become endemic in chickens. A multiplex reverse-transcriptase polymerase chain reaction (mRT-PCR) assay was designed for simultaneous detection and differentiation of avian H3, H5, H9 subtype AIVs and NDVs. Four primer sets were evaluated, three of which specifically targeted the hemagglutinin genes of H3, H5 and H9 AIVs, while the other targeted the NDV fusion gene. The sensitivity and specificity of the mRT-PCR assay was determined. The assay detected the major clades or genotypes of all of the reference AIVs and NDVs currently circulating in China. In addition, the mRT-PCR results obtained from screening 380 clinical swabs and 12 experimental tracheal samples were consistent with those obtained using conventional virus isolation methods. The mRT-PCR assay was established successfully for the detection and differentiation of avian H3, H5, and H9 subtype AIVs and NDVs. The method should, therefore, provide a valuable diagnostic tool for these infections.

Despite the long-term vaccination programs implemented in China, H9N2 avian influenza viruses (AIVs) continue to persist in chicken populations, even in vaccinated flocks. We previously demonstrated that H9N2 AIV isolated from chickens in China also underwent antigenic drift and evolved into distinct antigenic groups (C, D and E). To understand whether antigenic drift of viruses away from the vaccine strain partially contributed to the circulation of H9N2 AIV in China, we evaluated the protective efficacy of a commercial vaccine against different antigenic groups of H9N2 AIV. Challenge experiments using vaccinated chickens indicated that the vaccine prevented shedding of antigenic group C viruses, but not those of the more recent groups D and E. Vaccinated chickens, even those with vaccine-induced HI titers of 1:1024, shed virus after being infected with A/chicken/Shandong/ZB/2007, a representative virus of antigenic group D. Genetic analysis showed that the representative viruses of antigenic groups D and E possessed greater numbers of amino acid substitutions in the hemagglutinin protein compared to the vaccine strain and the antigenic group C virus, and many of which were located in antigenic sites. Our results indicated that the persistence of H9N2 AIV in China might be due to incomplete vaccine protection, and that the avian influenza vaccine should be regularly evaluated and updated to maintain optimal protection. Furthermore, the avian influenza vaccination policy also needs to be re-assessed, and increased veterinary biosecurity on farms, rather than vaccine application alone, should be implemented to prevent and control avian influenza.

A study is carefully conducted for the rocking response of a rigid circular foundation resting on a poroelastic half-space when subjected to seismic waves under the framework of Biot’s theory. The free-field waves, rigid-body scattering field waves and radiation scattering field waves are introduced to consider the complex behavior of the soil owing to the scattering phenomena caused by the existence of the foundation. The contact surface between the soil and the foundation is supposed to be perfectly bonded and fully permeable. Combining with the divided wave fields, two sets of dual integral equations elaborating the mixed boundary-value conditions are established, and then reduced to Fredholm integral equations. Therefore, with a semi-analytical method, the expressions of the rocking displacements are obtained. The numerical results of the rocking vibration of the foundation for incident P, SV and Rayleigh waves are presented. The influences of certain parameters, such as the permeability of the soil, the incident angle, Poisson’s ratio and the mass of the foundation, on the rocking vibration of the foundation are explored and studied. Different reactions are found when the foundation is excited by different waves.

An analytical approach is used to study the torsional vibrations of a rigid circular foundation resting on saturated soil to obliquely incident SH waves. Biot’s poroelastic dynamic theory is considered to characterize the saturated soil below the foundation, which is solved by Hankel transform later. In order to consider the scattering phenomena caused by the existence of the foundation, the total wave field in soil is classified into free-field, rigid-body scattering field and radiation scattering field. According to the classification of wave field and the mixed boundary-value conditions between the soil and the foundation, torsional vibrations of the foundation are formulated in two sets of dual integral equations. Then, the dual integral equations are reduced to Fredholm integral equation of the second kind to be solved. Combining with the dynamic equilibrium equations of the foundation, the expressions for the torsional vibrations of the foundation are obtained. Numerical results are presented to demonstrate the influence of excitation frequency, incident angle, the torsional inertia moment of the foundation and permeability of the saturated half-space on the torsional vibrations of the foundation.

An analytical approach is used to investigate dynamic responses of a track system and the poroelastic half-space soil medium subjected to a moving point load under three-dimensional condition. The whole system is divided into two separately formulated substructures, the track sub-system and the ground. The ballast supporting rails and sleepers is placed on the surface of the ground. The rail is modeled by introducing the Green function for an infinitely long Euler beam subjected to the action of the moving point load and the reaction of sleepers represented by a continuous mass. Using the double Fourier transform, the governing equations of motion are then solved analytically in the frequency–wave-number domain. The time domain responses are evaluated by the inverse Fourier transform computation for a certain load velocities. Computed results show that dynamic responses of the soil medium are considerably affected by the fluid phase as well as the load velocity.

Based on Biot’s fully dynamic poroelastic theory, the dynamic responses of the poroelastic half-space soil medium due to quasi-static and dynamic loads from a moving train are investigated semi-analytically. The dynamic loads are assumed to be generated from the rail surface irregularities. The vehicle dynamics model is used to simulate the axle loads (quasi-static loads) and the dynamic loads from a moving train. The compatibility of the displacements at wheel–rail contact points couple the vehicle and the track–ground subsystem, and yield equations for the dynamic wheel–rail loads. A linearized Hertzian contact spring between the wheel and rail is introduced to calculate the dynamic loads. Using the Fourier transform, the governing equations for the poroelastic half-space are then solved in the frequency–wavenumber domain. The time domain responses are evaluated by the fast inverse Fourier transform. Numerical results show that the dynamic loads can make important contribution to dynamic response of the poroelastic half-space for different train speed, and the dynamically induced responses lie in a higher frequency range. The ground vibrations caused by the moving train can be intensified as the primary suspension stiffness of the vehicle increases.

This paper presents an investigation of the steady-state response of pavement systems subjected to a moving traffic load. The traffic loads are simulated by four rectangular load pressures, and the rigid and flexible pavement systems are regarded as an infinite plate resting on a poroelastic half-space soil medium. The contact surface between the plate and the poroelastic half-space is assumed to be smooth and fully permeable. Kirchhoff small-deflection thin-plate theory is employed to analyze the plate, while Biot’s fully dynamic poroelastic theory is used to characterize the poroelastic half-space. The frequency wave-number domain solution of the pavement system is obtained by the compatibility condition between the plate and the poroelastic half-space. By applying the inverse fast Fourier transform, the time domain solution is obtained. Also, the influences of the load speed, the permeability of the soil, and the flexural rigidity of the plate on the response of the pavement system are investigated. The numerical results show that the influences of these parameters on the dynamic response of the pavement system are significant.

Surface-modified zeolite-filled chitosan (CS) membranes were prepared by incorporating 3-mercaptopropyltrimethoxysilane (MPTMS)-modified H-ZSM-5 zeolite into chitosan for pervaporation dehydration of aqueous ethanol solution. The physicochemical characterization by XPS, FT-IR, XRD, DMA and SEM showed that –SO3H group was readily grafted on the surface of H-ZSM-5 with the mediation of MPTMS and hydrogen peroxide, and the accompanying ion–ion interaction between –SO3H group on surface-modified H-ZSM-5 and –NH3+ group on chitosan substantially eliminated the nonselective voids at the chitosan–H-ZSM-5 interface of the filled membranes. The experimental results also revealed that H-ZSM-5 exhibited desirable size-selective and preferential adsorption effects for aqueous ethanol solution. As a result, modified H-ZSM-5 filled membranes showed higher swelling degree and permeation flux, and improved selectivity for aqueous ethanol solution. In comparison between chitosan control membrane (permeation flux 54.18 g/(m2 h) and separation factor 158.02 for 90 wt.% aqueous ethanol solution at 80 °C), the modified H-ZSM-5 filled membrane with 8 wt.% filling content exhibited a remarkably improved pervaporation performance with permeation flux 278.54 g/(m2 h) and separation factor 274.46 under the identical experimental condition.

The dynamic responses of track-ground system subjected to moving train passages are investigated by the substructure method. The whole system is divided into two separately formulated substructures, the track and the ground. The rail is described by introducing the governing function for an infinitely long Euler beam subjected to the action of moving axle loads of the train and the reactions of the sleeper. Sleepers are represented by a continuous mass and the effect of the ballast is considered. The soil is considered as fully saturated poroelastic medium and governed by Biot's theory. Using the double Fourier transform, the governing equations of motion are then solved analytically in the frequency-wave-number domain. The expressions of the rail displacement, the rail acceleration, the excess pore water pressure and soil stresses in the time domain are evaluated by the inverse Fourier transform. In particular, the effects of the rail rigidity are studied systematically. Computed results show that dynamic responses of the track-ground system are considerably affected by the rail rigidity as well as the load velocity.

The transient dynamic response of a pile embedded in transversely isotropic saturated soil and subjected to transient torsional loading is studied. The pile–soil system is divided into thin layers, and the Laplace transform is used to solve the governing equations of the soil layer and the pile segment. The matrix equations to describe the stiffness of the pile are deduced from the loading condition at the pile head and the compatibility between the pile and the soil. The displacement of the pile in the time domain is calculated by using the numerical inverse transformation. The pile’s slenderness ratio and its transverse isotropy are calculated numerically.