Optimum design for buckling of plain and stiffened composite axisymmetric shell panels/shells

The buckling of plain and discretely stiffened composite axisymmetric shell panels/shells made of repeated sublaminate construction is studied using the finite element method. In repeated sublaminate construction, a full laminate is obtained by repeating a basic sublaminate, which has a smaller number of plies. The optimum design for buckling is obtained by determining the layup sequence of the plies in the sublaminate by ranking, so as to achieve maximum buckling load for a specified thickness. For this purpose, a four-noded 48-dof quadrilateral composite thin shell element, together with fully compatible two-noded 16-dof composite meridional and parallel circle stiffener elements are used.     

Acoustic study of nano-crystal embedded PbO-P2O5 glass

Nano-crystal embedded PbO-P₂O₅ glass has been prepared and characterized by XRD and TEM measurements. The ultrasonic velocity and attenuation measured within the temperature range 80–300 K show significant structure and interesting feature with the presence of nano-crystalline region. The glass samples were prepared by melt-quench method and nano-crystals of different sizes were produced by heat treatment of the glasses for different durations of heating. All the processes were carried out at or above glass transition temperature. A theoretical model that takes account of the effects of thermally activated relaxation, anharmonicity as well as microscopic elastic inhomogeneities arising out of fluctuations has been successfully applied to interpret the variation of ultrasonic velocity and attenuation data. An interesting outcome of this application has been to propose a method for the determination of the size of nano-crystals from the ultrasonic attenuation data.     

Microstructure and Properties of Spark Plasma-Sintered ZrO2–ZrB2 Nanoceramic Composites

In a recent work, ¹ we have reported the optimization of the spark plasma sintering (SPS) parameters to obtain dense nanostructured 3Y-TZP ceramics. Following this, the present work attempts to answer some specific issues: (a) whether ZrO₂-based composites with ZrB₂ reinforcements can be densified under the optimal SPS conditions for TZP matrix densification (b) whether improved hardness can be obtained in the composites, when 30 vol% ZrB₂ is incorporated and (c) whether the toughness can be tailored by varying the ZrO₂–matrix stabilization as well as retaining finer ZrO₂ grains. In the present contribution, the SPS experiments are carried out at 1200°C for 5 min under vacuum at a heating rate of 600 K/min. The SPS processing route enables retaining of the finer t -ZrO₂ grains (100–300 nm) and the ZrO₂–ZrB₂ composite developed exhibits optimum hardness up to 14 GPa. Careful analysis of the indentation data provides a range of toughness values in the composites (up to 11 MPa·m^1/2), based on Y₂O₃ stabilization in the ZrO₂ matrix. The influence of varying yttria content, t -ZrO₂ transformability, and microstructure on the properties obtained is discussed. In addition to active contribution from the transformation-toughening mechanism, crack deflection by hard second phase brings about appreciable increment in the toughness of the nanocomposites.     

Experimental design in soap manufacturing for optimization of fuzzified process capability index

In manufacturing industries, the quality of a product depends on the combined effect of multiple input variables working singly or together and therefore attention has been given on process capability indices to shift from single to multivariate domain. In case of multivariable domain the capability to incorporate uncertainties at the time of decision making becomes necessary. Fuzzy system is introduced to take care of this requirement. In this article the process parameters of soap manufacturing industries have been analyzed. The process capability is determined using Fuzzy Inference System rule editor based on a set of justified if then statements as applicable for the process. The data has been collected in linguistic form to derive its process capability, using a set of justified rules and the effect of each factor has been determined using Design of Experiments (DoE) and analysis of variance technique (ANOVA) for improving the soap quality from perspective of its softness. This article ventures to propose a new methodology by integrating Fuzzy with DoE providing better result followed by DoE and Fuzzy Inference system in isolation.     

Transient testing of soy methyl ester fuels in an indirect injection,compression ignition engine

An evaluation of the exhaust emissions from a compression ignition engine for fuels composed of 100 and 30% methyl esters of soy oil (SME) is described. These fuels were compared with a low-sulfur, petroleum #2 diesel fuel in a Caterpillar 3304, prechamber, 75 kW diesel engine, operated over heavy- and light-duty transient test cycles developed by the United States Bureau of Mines. More than 60 h of testing was performed on each fuel. The objective was to determine the influence of the fuels upon diesel particulate matter (DPM) and gaseous emissions. The effect of a modern diesel oxidation catalyst (DOC) also was determined in an effort to minimize emissions. Neat SME produced a higher volatile fraction of the DPM, but much less carbon soot fraction, leading to overall DPM reductions of 23 to 30% for the light- and heavy-duty transients. The DOC further reduced the volatile fraction and the total DPM. The SME fuel reduced gaseous emissions of CO by 23% and hydrocarbons by over 30% without increasing NO_x. The DOC further reduced CO and hydrocarbon levels. Mutagenicity of the SME exhaust was low. Results indicate that SME fuel, used with a proper DOC, may be a feasible emission reduction technology for underground mines. References to specific products do not imply endorsement by the U.S. Bureau of Mines, a now defunct agency.     

A simplified model of nitric oxide emission from a circulating fluidized bed combustor

A simplified mathematical model leading to a closed form of solution is developed for estimation of nitric oxide emission from a coal fired circulating fluidized bed (CFB) furnace. The furnace is divided into two sections: a lower section below and an upper section above the secondary air injection level. Reactions in the cyclone and the return leg are neglected. Furnace dimensions, coal feed rate, coal composition and furnace temperature are inputs to the model which was validated against several pilot scale and commercial units. Experimental results from two pilot plants and two commercial power plants agree with model predictions. A sensitivity analysis was carried out using the model to examine the effect of different operating parameters and coal properties on the overall NO emission from the furnace. It was found that excess air and furnace temperature are most important factors influencing the NO emission level. The primary to secondary air ratio influences the NO emission level reasonably. Properties of coal are other factors which affect the NO emission to a large extent. The model, though it invovles some simplification, predicts the overall emission of NO with a level of accuracy accepted in commercial operation.     

The influence of heating element temperature on productivity

A study to determine the most optimal heating element for any given processing configuration yields a surprisingly simple log-linear dependence of the productivity on the heating-element temperature. Aluminum, iron, and aluminum-oxide processing efficiencies are studied for conditions that span heat treating to melting. The authors note that, in general, the highest element temperature that may effectively be used for a given heating process is the high-productivity solution.     

NodeWiz: Fault-tolerant grid information service

Large scale grid computing systems may provide multitudinous services, from different providers, whose quality of service will vary. Moreover, services are deployed and undeployed in the grid with no central coordination. Thus, to find out the most suitable service to fulfill their needs, or to find the most suitable set of resources on which to deploy their services, grid users must resort to a Grid Information Service (GIS). This service allows users to submit rich queries that are normally composed of multiple attributes and range operations. The ability to efficiently execute complex searches in a scalable and reliable way is a key challenge for current GIS designs. Scalability issues are normally dealt with by using peer-to-peer technologies. However, the more reliable peer-to-peer approaches do not cater for rich queries in a natural way. On the other hand, approaches that can easily support these rich queries are less robust in the presence of failures. In this paper we present the design of NodeWiz, a GIS that allows multi-attribute range queries to be performed efficiently in a distributed manner, while maintaining load balance and resilience to failures.