A statistical analysis on the mechanical properties of nanocomposite modified asphalt mixtures

This study aimed to characterize the rate of change that takes place in the mechanical properties of polymer-nanocomposite asphalt (PNMA) mixtures due to altering asphalt binder grade and styrene-butadiene-styrene (SBS) type. Laboratory testing program included Marshall stability, resilient modulus, and wheel-tracking tests. Test results were compared and analyzed statistically by means of two-way analysis of variance and Tukey test. Variance analysis indicated the significant effect of both binder type and SBS grade on mechanical properties of asphalt mixtures. Interaction between binder type and SBS grade is also meaningful in all the experiments. The results also show that the binder type is the primary affecting factor, followed by the SBS grade.     

Requirements for enforcing digital rights management in multicast content distribution

In this paper, we have collected the requirements for Digital Rights Management from various sources, and presented them as a set of 11 requirements, associated with five categories. We discuss each requirement, provide the motivation for each entry, and illustrate how each one could be achieved. Four example commercial DRM systems are briefly explained, and the requirements that they meet are presented in tabular format. None of the example systems meet all the requirements that we have listed. The security threats that are faced by DRM systems are briefly discussed. All of the example systems are based on unicast data distribution. The use of multicast data distribution can help the source of the data and the underlying network to reduce their resource requirements when distributing high-quality content at minimum cost and delay. Up to now, there has been little motivation to use standard Internet Protocol multicast because it does not support any protection mechanisms for the delivered data. Given that significant progress has been made by other researchers in providing “secure” multicast data distribution, we explore how the use of secure multicast as a distribution technology can bring significant improvement for some requirements, while making the achievement of others more difficult. We review how the architecture of the distribution must change to permit capturing the advantages of multicast distribution while retaining as much as possible the features of unicast systems. Some open problems are identified.     

Exact solution for stability analysis of moderately thick functionally graded sector plates on elastic foundation

In this article, an exact analytical solution for buckling analysis of moderately thick functionally graded (FG) sector plates resting on Winkler elastic foundation is presented. The equilibrium equations are derived according to the first order shear deformation plate theory. Because of the coupling between the bending and stretching equilibrium equations of FG plates, these plates have deflection under in-plane loads lower than the critical buckling load acting on the mid-plane. The conditions under which FG plates remain flat in the pre-buckling configuration are investigated and the stability equations are obtained based on the flat plate assumption in the pre-buckling state. The stability equations are simplified into decoupled equations and solved analytically for plates having simply supported boundary condition on the straight edges. The critical buckling load is obtained and the effects of geometrical parameters and power law index on the stability of functionally graded sector plates are studded. The results for the critical buckling load of moderately thick functionally graded sector plates resting on elastic foundation are reported for the first time.     

Quality assessment of polymer replication by hot embossing and micro-injection moulding processes using scanning mechanical microscopy

This paper describes observations and metrological analyses made to compare the replication quality of polymeric replicas obtained by filling micro-cavities using both hot embossing and micro-injection moulding processes. The experiments are performed with polypropylene (PP) at a constant melt temperature and a constant mould temperature, whereas hot embossing tests are carried out with the same polymer at temperatures close to the softening one.The results concerning the micro-cavities filling provide information on the reliability about the possibilities of replication topographical surface geometries. The data obtained by scanning mechanical microscopy (SMM) are used to determine the comparative filling ratio values.     

On singularly perturbed <Emphasis Type="Italic">q</Emphasis>-difference-differential equations with irregular singularity

We study a q-analog of a singularly perturbed Cauchy problem with irregular singularity in the complex domain. We construct solutions of this problem that are holomorphic on open half-q-spirals. Using a version of a q-analog of the Malgrange–Sibuya theorem obtained by J.-P. Ramis, J. Sauloy, and C. Zhang, we show the existence of a formal power-series solution in the perturbation parameter which is the q-asymptotic expansion of these holomorphic solutions.     

Research, development and manufacturing plans at CAMD

 The X-ray micromachining activities at CAMD are described. Through the HI-MEMS Alliance Program, CAMD has developed an extensive technical infrastructure and process experience. The “X-ray Print-Shop” supports prototyping and is prepared for cost effective low-to-medium volume production of primary parts with high aspect ratio, including exposure of multiple level devices with alignment, as well as tilted and rotated exposures. Important lessons learnt during the course of the program will be reported. An up-grade of the facility to install a 7.5 Tesla superconducting wiggler in the ring is in progress. It will produce hard X-rays for ultra-deep X-ray lithography. Received: 25 August 1997/Accepted: 3 September 1997     

The inverse design of the wind turbine blade sections by the singularities method

The aerodynamic characteristics of wind turbines are closely related to the geometry of their blades. The innovation and the technological development of wind turbine blades can be centred on two tendencies. The first is to improve the shape of existing blades; the second is to design new shapes of blades. The aspiration in the two cases is to achieve an optimal circulation and hence enhancing some more ambitious aerodynamic characteristics. This paper presents an inverse design procedure, which can be adapted to both thin and thick wind turbine blade sections aiming to optimise the geometry for a prescribed distribution of bound vortices. A method for simulating the initial contour of the blade section is exposed, which simultaneously satisfy the aerodynamic and geometrical constraints under nominal conditions. A detailed definition of the function characterising the bound vortex distribution is presented. The inviscid velocity field and potential function distributions are obtained by the singularities method. In the design method implemented, these distributions and the circulation of bound vortices on the camber line of the blade profile, are used to rectify its camber in an iterative calculation leading to the final and optimal form of the blade section once convergence is attained. The scheme proposed has been used to design the entire blade of the wind turbine for a given span-wise distribution of bound circulation around the blade contour.     

A Best Practice Guide to Resource Forecasting for Computing Systems

Recently, measurement-based studies of software systems have proliferated, reflecting an increasingly empirical focus on system availability, reliability, aging, and fault tolerance. However, it is a nontrivial, error-prone, arduous, and time-consuming task even for experienced system administrators, and statistical analysts to know what a reasonable set of steps should include to model, and successfully predict performance variables, or system failures of a complex software system. Reported results are fragmented, and focus on applying statistical regression techniques to monitored numerical system data. In this paper, we propose a best practice guide for building empirical models based on our experience with forecasting Apache web server performance variables, and forecasting call availability of a real-world telecommunication system. To substantiate the presented guide, and to demonstrate our approach in a step by step manner, we model, and predict the response time, and the amount of free physical memory of an Apache web server system, as well as the call availability of an industrial telecommunication system. Additionally, we present concrete results for a) variable selection where we cross benchmark three procedures, b) empirical model building where we cross benchmark four techniques, and c) sensitivity analysis. This best practice guide intends to assist in configuring modeling approaches systematically for best estimation, and prediction results.     

High-power potassium-titanyl-phosphate (KTP/532) laser vaporization prostatectomy: 24 hours later

All persons 65 years and older are recommended to be immunised against influenza each autumn. As immunisation rates remain low, we conducted a randomised control trial in a three-partner urban general practice to evaluate the differential effectiveness of a single postcard reminder in a general practice setting compared to usual care. All non-residential patients aged 65 years and over were identified from the age/sex/disease register. After exclusions, 325 patients were stratified by sex (125 men and 200 women) and randomised to receive either a postcard reminder in large print mailed in April or usual care. General practitioners (GPs) were blind to the randomisation. A blinded record audit performed in July demonstrated that the postcard was effective in increasing immunisation for men (chi(2)1df = 3.85; p = 0.05) but not for women (chi(2)1df = 0.45; p = 0.50). After adjusting for 1995 immunisation status, the effect of the postcard on immunisation rates was even stronger in men (Wald chi(2)1df = 6.20; p = 0.01) but remained non-significant in women (Wald chi(2)1df = 1.38; p = 0.24). With this adjustment, the odds of having the 1996 flu vaccine for men sent the postcard reminder were three times that of men in the control group (OR = 3.0; 95% CI 1.3-6.9). In a general practice setting, a single postcard reminder appears to be a promising way to boost influenza immunisation rates among ageing men. Replication of the study is recommended.     

The cylindrical banyan multicomputer: A reconfigurable systolic architecture

A new reconfigurable systolic multicomputer architecture is presented. The proposed architecture, called the Cylindrical Banyan Multicomputer (CBM), is based on the structure of a modified banyan network where every node of the network graph is composed of an application processor, a local memory and a communication processor, and network's inputs and outputs are merged (fused). The CBM has one of the lowest (cost) X (delay) among known multicomputer architectures based on regular networks. It is shown that a variety of computation structures such as pipelines, rings, and trees may be constructed and reconfigured in an optimal or a nearby optimal way on the CBM architecture, and that various basic algorithms can be executed very efficiently in a systolic manner. It is also shown that the CBM is an easily diagnosable and fault-tolerant system.