Application Semantics and Seamlessness Based Admission Control Policy for Multimedia Mobile Networks

With the advent of different types of applications in bandwidth scarce cellular environment, efficient usage of bandwidth while providing the required Quality of Service (QoS) for these applications becomes a challenging issue. In a cellular environment, there is always a tradeoff between the efficient usage of network bandwidth and uninterrupted (seamless) communication to each user. The paramount importance is always given to the seamlessness, which could be achieved by the reservation based call admission policies. The degree of seamlessness is proportional to the amount of reservation. The objective of any call admission policy is to provide seamless communication with better bandwidth usage. This paper aims at achieving this objective by improving the Shadow Cluster call admission algorithm proposed recently in [8] for providing a high degree of seamlessness. Our proposed scheme exploits application semantics (loss profile) and delay properties of the application during call admission for better bandwidth utilisation and call acceptance. Moreover, efficient usage of bandwidth is highly desired under peak load conditions and the same is achieved by our scheme. We have conducted extensive simulation studies to evaluate the effectiveness of the proposed scheme under diverse traffic conditions by comparing it with the shadow cluster algorithm. The results clearly indicate that our scheme offers better bandwidth utilization and call acceptance rate than the shadow cluster algorithm for the same call drop percentage.     

Oxidation of Aqueous Sulphur Dioxide Catalysed by Poly-4-vinylpyridine–Cu(II) Complex. Part 2: Combined Homogeneous and Heterogeneous Phase Oxidation

Aqueous phase oxidation of sulphur dioxide at low concentrations catalysed by a PVP–Cu complex in the solid phase and dissolved Cu(II) in the liquid phase is studied in a rotating catalyst basket reactor (RCBR). The equilibrium adsorption of Cu(II) and S(VI) on PVP particles is found to be of the Langmuir-type. The diffusional effects of S(IV) species in PVP–Cu resin are found to be insignificant whereas that of product S(VI) are found to be significant. The intraparticle diffusivity of S(VI) is obtained from independent tracer experiments. In the oxidation reaction HSO₃⁻ is the reactive species. Both the S(IV) species in the solution, namely SO₂(aq) and HSO₃⁻, get adsorbed onto the active PVP–Cu sites of the catalyst, but only HSO₃⁻ undergoes oxidation. A kinetic mechanism is proposed based on this feature which shows that SO₂(aq) has a deactivating effect on the catalyst. A rate model is developed for the three-phase reaction system incorporating these factors along with the effect of concentration of H₂SO₄ on the solubility of SO₂ in the dilute aqueous solutions of Cu(II). Transient oxidation experiments are conducted at different conditions of concentration of SO₂ and O₂ in the gas phase and catalyst concentration, and the rate parameters are estimated from the data. The observed and calculated profiles are in very good agreement. This confirms the deactivating effect of non-reactive SO₂(aq) on the heterogeneous catalysis. © 1997 SCI.     

Optimum tolerance synthesis for complex assembly with alternative process selection using Lagrange multiplier method

Any part cannot be manufactured to the required nominal dimensions due to inherent variations in workmanship, material, and machine. The specification of tolerance on part dimensions plays a major role on performance, quality, and cost of the product. Distribution of tolerance among the components of an assembly is known as tolerance allocation. The selection of alternative processes for tolerance allocation also plays a vital role in reducing manufacturing cost. Near-optimal allocated tolerances are obtained using nontraditional optimization techniques in which the solutions are achieved randomly. Also, there is a chance for omitting the better process for allocation. The results of successive run of the program based on these techniques will not yield consistent results. An attempt has been made in this work to solve the above problem using Lagrange multiplier method for complex assemblies with univariate search method. The methodology has been demonstrated on wheel mounting assembly. The example product after implementing the proposed method would yield 1.4% savings in manufacturing cost as compared with the cost obtained by Singh.     

Preparation and properties of nanoparticle and long-fiber-reinforced unsaturated polyester composites

In this study, a new approach was used to prepare polymer composites reinforced by both nanoparticles and continuous fibers. Carbon nanofibers were prebound onto glass fiber mats, and then unsaturated polyester composites were prepared by vacuum-assisted resin transfer molding. Mechanical and thermal properties of these composites were measured and compared with those of the composites synthesized by premixing carbon nanofibers with the polymer resin. Flexural strength and modulus of composites improved with the incorporation of nanoparticles. Specifically, the property improvement was higher in the case of the composites prepared by the new prebound method. It was also found that carbon nanofibers increased the glass transition temperature and reduced the thermal expansion coefficient of unsaturated polyester composites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Innovative approach to investigating the microstructure of calcified tissues using specular reflectance Fourier transform-infrared microspectroscopy and discriminant analysis

Although bone fracture has become a serious global health issue, current clinical assessments of fracture risk based on bone mineral density are unable to accurately predict whether an individual is likely to suffer a fracture. There is increasing recognition that the chemical structure and composition, or microstructure, of mineralized tissues has an important role to play in determining the fracture resistance of bone. The objective of this preliminary study was to evaluate the use of specular reflectance Fourier transform infrared (SR FT-IR) microspectroscopy in conjunction with discriminant analysis as an innovative technique for providing future insights into the origins of orthopedic abnormalities. The impetus for this approach was that SR FT-IR microspectroscopy would offer several advantages over conventional transmission methods. Bone samples were obtained from young racehorses at known fracture predilection sites and spectra were successfully obtained from calcified cartilage and subchondral bone for the first time. By applying discriminant analysis to the spectral data set in biologically relevant regions, microstructural differences between groups of individuals were found to be related to features associated with both the mineral and organic components of the bone. The preliminary findings also suggest that differences in bone microstructure may exist between healthy individuals of the same age, raising important questions around the normal limits of individual variation and whether individuals may be predisposed to later fracture as a result of detrimental microstructural changes during early growth and development.     

Genetic algorithm based deformation control and clamping force optimisation of workpiece fixture system

In re-engineering mass production industry, design and production of components are frequently changed according to the customer needs within a very short span of time. This leads to rising difficulty in maintaining the accuracy of every finished component. It also induces the long setup time of the cutting tools and machine tools affecting the production rate of the components. To reduce the production time and to improve the accuracy of the finished product, proper fixture element is essential. The accuracy of the finished work-piece strongly depends on the position of the locators and clamps in the work-piece fixture system. The finite element analysis tool is well suited to predict the active and passive forces on the work piece-fixture system. The accuracy of the workpiece not only depends on the clamping force but also depends upon the locator force (reaction force). This paper presents the optimisation of the locations of active (clamp) and passive (locator/support) elements in the workpiece-fixture system using genetic algorithm (GA) with ANSYS parametric design language (APDL) of finite element analysis. Three case studies are given to illustrate the application of the proposed approach. Finally the case study results have been compared with the Li and Melkote (1999a Li, B and Melkote, SN. 1999a. An elastic contact model for the prediction of workpiece-fixture contact forces in clamping. ASME Journal of Manufacturing Science and Engineering, 121(3): 485–493.  [Google Scholar]) [Li, B. and Melkote, S.N., 1999a. An elastic contact model for the prediction of workpiece-fixture contact forces in clamping. ASME Journal of Manufacturing Science and Engineering, 121(3), 485–493] study. This presented prediction method is conceptually simple and computationally efficient.     

A new algorithm for minimizing surplus parts in selective assembly by using genetic algorithm

Precision assemblies are produced from low precision subcomponents by partitioning and assembling them randomly from their corresponding groups. Surplus part is one of the important issues, which reduces the implementation of selective assembly in real situations. A new algorithm is introduced in this present paper to reduce surplus parts almost to zero and it is achieved in two stages by using a genetic algorithm. For demonstrating the proposed algorithm, a gearbox shaft assembly is considered as an example problem in which the shaft and pulley are manufactured in wider tolerance and partitioned in three to nine bins. The surplus parts are divided into three bins equally and a best combination of groups is obtained for both cases. It is observed that nearly 995 assemblies are produced out of one thousand subcomponents with the manufacturing cost savings of 19.5% for T _max and 992 assemblies are produced with 13.5% saving in manufacturing cost for 0.9T _max.     

Carbon nanofiber paper and its effect on cure kinetics of low temperature epoxy resin

In this study, the preparation, properties, and characterization of thin films or “nanopapers” of carbon nanofibers (CNFs) were studied. Specifically, a layer-by-layer nanopaper preparation method was used, which significantly improved the mechanical properties of nanopapers. The effect of CNF nanopaper on the cure kinetics of a low temperature epoxy resin was studied. A modified autocatalytic model was used to represent the reaction kinetics. It was found that the presence of CNF nanopaper substantially increased the resin reaction rate and final conversion. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Continuous Synthesis of Device‐Grade Semiconducting Polymers in Droplet‐Based Microreactors

A method is reported for the controlled synthesis of device‐grade semiconducting polymers, utilizing a droplet‐based microfluidic reactor. Using poly(3‐hexylthiophene) (P3HT) as a test material, the reactor is shown to provide a controlled and stable environment for polymer synthesis, enabling control of molecular weight via tuning of flow conditions, reagent composition or temperature. Molecular weights of up to 92 000 Da are readily attainable, without leakage or reactor fouling. The method avoids the usual deterioration in materials quality that occurs when conventional batch syntheses are scaled from the sub‐gram level to higher quantities, with a prototype five‐channel reactor producing material of consistent molecular weight distribution and high regioregularity (>98%) at a rate of ≈60 g/day. The droplet‐synthesized P3HT compares favorably with commercial material in terms of absorption spectrum, polydispersity, regioregularity, and crystallinity, yielding power conversion efficiencies of up to 4% in bulk heterojunction solar cells with [6,6]‐phenyl‐C61‐butyric acid methyl ester.     

An experimental study on the shattering behavior of a high strength armour steel under blast and long rod penetrator impact

Armour steel plates with drilled holes are filled with explosive and subjected to single or multiple blasts to induce shattering. The critical diameter for shattering under explosive detonation, found from the experiments matches closely with that of the long rod penetrator impacted plates. The damage pattern and fracture surface of the tested samples under blast effect have been compared with plates impacted with long rod penetrators for matching the observed shattering behavior. Difference in the shattering behavior of the armour steel subjected to single and multiple blasts has also been presented.