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The adverse effects of ground vibrations can be eliminated or prevented by installation of various types of wave barriers, such as a row of holes. The analysis is accomplished with the aid of a series of field experiments and numerical simulation. Three-dimensional semi-analytical boundary element models are established to use a row of holes as active wave barrier to isolate the ground vibrations generated by the machine foundation laid on the surface of saturated soil foundation, and the effects of the model parameters on isolation effectiveness are investigated and discussed in detail. A simple single program multiple data parallel algorithm is developed with the aid of Matlab software to increase calculating efficiency. The results show that a row of holes can isolate the ground vibrations successfully. Increasing the radius and the depth and decreasing the net spacing between two successive holes can all result in an increase in the screening effectiveness. According to the results, it is suggested in the design that the hole radius should take the value of 0.1~0.15 R (γR is the Rayleigh wave length), and the hole depth and the net spacing should take the value no more than 1.0γR and 0.1γR, respectively. Moreover, the distance between the machine foundation and barrier can affect the screening effectiveness, and the larger the distance is, the poorer the screening effectiveness is. The number of holes in a row has less effect on the screening effectiveness. However, the bigger the number of holes in a row is, the larger the screening zone behind the barriers is. [ABSTRACT FROM AUTHOR]

The surrounding environment of shield tunnel construction under different geological conditions directly affects the safety of subway construction, so the real-time monitoring of surrounding environment has become a hot issue in subway construction. Among them, the settlement in the process of tunnel construction is the top priority of environmental monitoring. Tunnel long-term settlement monitoring should be conducted continuously from the construction stage to the trial operation stage, as well as to the operation stage. However, for most of the shield-tunnel engineering in practice, it is difficult to ensure the continuous long-term tunnel settlement monitoring due to the influence of various factors. The cumulative settlement data of operating tunnel can only reflect the deformation law of metro shield tunnel at a certain stage. Therefore, it is difficult to evaluate the actual deformation characteristic and the stress state of the shield tunnel. The theoretical calculation and example analysis were performed to verified the above viewpoint. The results show that the continuity and integrity of the measured settlement data should be ensured when they were used for evaluating the structural safety of the operating shield tunnel. However, once the measured settlement data were discontinuous, the deformation law, the longitudinal deformation and the stress characteristic of the operating shield tunnel should be evaluated respectively using the combination of the cumulative settlement data and the elevation data. This study can effectively improve the monitoring effect of shield tunnel settlement environment, and improve the reliable technical support for the safe and efficient construction of the tunnel. [ABSTRACT FROM AUTHOR]

Hollow copper microspheres with pore size about 3 µm and spherical shell around 150 nm were successfully prepared by electroless plating using polystyrene (PS) as sacrificial templates and the kinetics were studied concerning the empirical rate law. The effects of plating bath composition on the amount, microstructure and composition of the deposited copper shells were investigated. pH was the most important factor for copper deposition rate and amount of copper deposits. The amount of by-product Cu2O decreased with increasing pH values and the deposited copper agglomerated when pH value reached 13.41. The addition of stabilizers (2, 2-bipyridine, potassium ferrocyanide and methanol) had a very negative effect on the microstructure of the deposited copper shells. PS templates were removed by sintering and the remanent copper deposits with high purity maintained good spherical shell structure. In addition, the kinetic equation of electroless copper plating (ECP) using PS as the substrate was determined and the activation energy (Ea) was 59.77 kJ · mol-1. The prepared hollow copper microspheres with high porosity are ideally suitable for synthesizing energetic materials and this method might also be used for fabricating other hollow metal microspheres. [ABSTRACT FROM AUTHOR]

Multiregionai clinical trials (MRCTs) present great opportunities but also challenges to the trial community. To address the challenges and fully realize the opportunities, a PhRMA MRCT Cross-Functional Key Issue Team (KIT) was formed in 2008. One of the work streams within the KIT particularly focuses on the assessment of consistency of treatment effects across regions. As the main objective of this work stream, this research explores a number of definitions for consistency assessments. We address the issues primarily for superiority trials with continuous endpoints, then extend briefly to noninferiority trials, random effect models, binary endpoints, and survival endpoints. Computations and simulations are used to study the properties of the proposed definitions, particularly the power for showing consistency. To illustrate applications of the methods, we use a trial example with a continuous endpoint. We discuss considerations for trial design as well as for data analysis. The consistency assessment relies heavily on the definition of regions and the number of regions. We recommend working with health authorities to define region in a manner that is sensible from a practical interpretation standpoint and also makes region consistency assessment a feasible undertaking. [ABSTRACT FROM AUTHOR]