An integrated approach to geomaterial characterization is advocated that combines geology, in-situ testing, fabric studies, routine index experiments and advanced laboratory testing. It is shown that advanced laboratory testing can explore features such as kinematic yielding and anisotropy in stiffness or shear strength that would otherwise be impossible to quantify. A detailed study performed in London clay at the new Heathrow Terminal 5 site is used to illustrate the arguments made. It is shown that the London clay has strong anisotropy in stiffness, is highly non-linear over the strain range of engineering interest, has markedly anisotropic shear strength characteristics and exhibits a pronounced degree of brittleness. These features can impact significantly on the practical design and analysis of civil engineering works including shallow and deep foundations, tunnels and excavations, and the stability of slopes.

The penetration of a model pile through sand was investigated via a numerical analysis. Data from nine triaxial compression tests on dense specimens at different stress levels was generalized and used to create an empirical non-linear plastic hardening stress-strain relation for use in the analysis. As the computer program used is capable of large displacement analyses in radial symmetry, we expected that the analysis would easily reproduce the tip resistance penetration profile of the model pile in sand of known density and stress. However, initial attempts led to over-prediction. Successful analyses required both successive reformations of the mesh and the complete elimination of the dilatant peak in soil strength, which is naturally eliminated under large confining stress directly beneath the advancing tip, and that soil in the far-field had strained insufficiently to reach peak strength. Thus, the soil around the shaft must have been sheared to a critical state as it flowed past the tip. The hypothesis that the resistance to displacement piles in sand is mainly a function of the deformability of the sand was again proven, and the use of peak strength in the traditional bearing capacity formulae was found to be inappropriate. Independent investigation in this direction is needed to quantify the hypothesis.

The presence of wrinkles in a membrane is the main factor that induces surface errors on space planar film reflect-arrays. Based on the commercial finite element (FE) package ABAQUS, a numerical procedure for membrane wrinkle analysis was set up, and used to analyze a square planar film reflect-array under pure shear force to evaluate its induced wrinkle characteristics. First, the effect of shear force on the wrinkle pattern of the array was studied and validated by experiment. Second, the effect of prestress was studied. When the prestress increases, the quantity of the wrinkles increases, and the amplitude of the wrinkles decreases. Third, the influence of the boundary conditions was investigated. A frame side edge structure has a relatively smooth surface, but also relatively high stress. Finally, the behavior of a joint seam was analyzed. The results indicate that a joint band has a significant influence on the wrinkle pattern of the membrane.

A numerical algorithm using a bilinear or linear finite element and semi-implicit three-step method is presented for the analysis of incompressible viscous fluid problems. The streamline upwind/Petrov-Galerkin (SUPG) stabilization scheme is used for the formulation of the Navier-Stokes equations. For the spatial discretization, the convection term is treated explicitly, while the viscous term is treated implicitly, and for the temporal discretization, a three-step method is employed. The present method is applied to simulate the lid driven cavity problems with different geometries at low and high Reynolds numbers. The results compared with other numerical experiments are found to be feasible and satisfactory.

In this study a new dynamic model of a rotor system is established based on the Hamilton principle and the finite element method (FEM). We analyze the dynamic behavior of the rotor system with the coupled effects of the nonlinear oil film force, the nonlinear seal force, and the mass eccentricity of the disk. The equations of the motion are solved effectively using the fourth order Runge-Kutta method in MATLAB. The dynamic behavior of the system is illustrated by bifurcation diagrams, largest Lyapunov exponents, phase trajectory diagrams, and Poincaré maps. The numerical results show that the rotational speed of the rotor, the pressure drop in the seal, the seal length, the seal clearance, and the mass eccentricity of the disk are the key parameters that significantly affect the dynamic characteristics of the rotor system. The motion of the rotor system exhibits complex types of periodic, quasi-periodic, double-periodic, multi-periodic, and chaotic vibrations. This analysis can be used to guide the design of seal parameters and to diagnose the vibration of rotor/bearing/seal systems.

In this paper, a series of experiments were performed by high speed milling of Ti-6.5Al-2Zr-1Mo-1V (TA15) by use of polycrystalline diamond (PCD) tools. The characteristics of high speed machining (HSM) dynamic milling forces were investigated. The effects of the parameters of the process, i.e., cutting speed, feed per tooth, and depth of axial cut, on cutting forces were studied. The cutting force signals under different cutting speed conditions and different cutting tool wear stages were analyzed by frequency spectrum analysis. The trend and frequency domain aspects of the dynamic forces were evaluated and discussed. The results indicate that a characteristic frequency in cutting force power spectrum does in fact exist. The amplitudes increase with the increase of cutting speed and tool wear level, which could be applied to the monitoring of the cutting process.

This study addresses heat transfer performance of various configurations of coiled non-circular tubes, e.g., in-plane spiral ducts, helical spiral ducts, and conical spiral ducts. The laminar flow of a Newtonian fluid in helical coils made of square cross section tubes is simulated using the computational fluid dynamic approach. The effects of tube Reynolds number, fluid Prandtl number, coil diameter, etc., are quantified and discussed. Both constant wall temperature and constant heat flux conditions are simulated. The effect of in-plane coil versus a cylindrical design of constant coil, as well as a conical coil design is discussed. Results are compared with those for a straight square tube of the same length as that used to form the coils. Advantages and limitations of using coiled tubes are discussed in light of the numerical results.

The naphthalene decomposition in a corona radical shower discharge (CRS) was investigated, with attention paid to the influences of voltage and initial naphthalene density. The OH emission spectra were investigated so as to know the naphthalene decomposing process. The by-products were analyzed and a decomposing theory in discharge was proposed. The results showed that higher voltage and relative humidity were effective on decomposition. The initial concentration affected the decomposing efficiency of naphthalene. When the initial naphthalene density was 17 mg/m³, the decomposition rate was found to be 70% under 14 kV. The main by-products were carbon dioxide and water. However, a small amount of carbonic oxide, 1,2-ethanediol and acetaldehyde were found due to the incomplete oxidization.

Median noise barriers, like parallel noise barriers, can be employed to reduce the impact of traffic on roadside communities via the direct propagation path. The performance of different shapes of median barriers was compared using reactive and passive surfaces and a 2D boundary element method (BEM). In the case of reactive surfaces, quadratic residue diffusers (QRDs) and primitive root diffusers (PRDs) were used on the top and stem surfaces of median barriers. To introduce passive barriers, two different absorbent materials including fibrous material and a grass surface with flow resistivity of 20 000 and 2500 kg/(s·m²), respectively, were similarly applied. The effect of thin absorptive barriers was similar at lower frequencies and better at mid and high frequencies to that of their equivalent rigid barriers. More improvement was achieved by covering the top surface of thick barriers with grass rather than with fibrous material. The performance of QRD and PRD barriers where the diffuser was located on the top surface was more frequency dependent than that of barriers coated with fibrous material. A comparison of the average A-weighted insertion loss in the thick barriers showed that the greatest improvement (2.59 dB (A)) was achieved using a barrier of 30-cm thickness covered with grass.