Repeated Price Search

Consumers check few sites in online purchases. Previous research and experiments we perform demonstrate that consumers can not calculate the optimal strategy for price search. They use heuristics whose performance is better than random and less than optimal. To investigate online price search performance we survey student online textbook purchases. Students achieve good performance because they start with a good strategy and online market organization of marketplace and meta-search sites. An important factor is that algorithms at sites searched perform calculations that reduce the computational complexity of the search.     

Optimal monolithic configuration for heat integrated ethanol steam reformer

A design concept for optimal design of monolith catalyst is presented through modeling of transport–kinetic interactions in a monolith catalyst. We argue that reactors employing monolithic catalysts should be based on its optimal choice of geometry. In line with that argument, we present a thorough analysis of the geometrical parameters influencing the performance of non-isothermal reactor operation. In this study, an optimal monolith configuration is estimated to be a combination (d_h, t_w) of (0.9 mm, 0.2 mm) for a compact ethanol reformer to produce hydrogen for portable applications where maximum volumetric reactor activity exists. A three-dimensional modeling framework is developed for the resulting optimal monolithic catalyst design that couples the reforming section with a suitable heat source in a recuperative way. As a result, greater ethanol conversion is obtained from the monolith channels near the periphery of the block. The coupling with combustion could predict the formation of cold and hot spots inside the reactor, their nature being dependent on the flow configuration. Further, the effect of altering the feed inlet operating conditions over the variation of ethanol conversion and temperature inside the reactor is also analyzed. The increase in reforming inlet velocity decreases the outlet conversion and shifts the cold spot, forward and deeper in co-flow configuration. The decreasing inlet feed temperature enhances the transfer of heat, eliminating the cold spot.     

New concepts in early failure modelling

The problem of early failure modelling has been discussed comprehensively. Present models have been discussed and new models are suggested. A drawback of failure rate not being finite at t = 0 for some of the present models is eliminated in the suggested models.     

Stepwise Formation of Some Bivalent Metal Chelates with Sodium Alizarin Sulphonate

The stepwise protonation constants of the ligand and the stability constants of Alizarin Red S with some bivalent metal ions, Pb²⁺, Cu²⁺, Zn²⁺, and Hg²⁺ have been determined at 30° and at various ionic strengths viz. 0.02, 0.05, 0.15 and 0.20, maintained by sodium perchlorate solution. The formation of the chelate is evident from the shift between the (i) ligand and (ii) ligand and metal titration curves. From the values of the stepwise protonation constants and metal ligand stability constants at various ionic strengths, thermodynamic formation constants were evaluated by extrapolation to zero ionic strength. The order of stability constants was found to be: Cu > Pb > Zn > Hg     

A new model of software reliability prediction

To start with, a new generalized structure of basic equations of software reliability has been defined. In this new structure, the software reliability has been defined in terms of execution time T and operational time t. Then, a new model of software reliability has been proposed and fitted into the new structure.     

Optimum design of reliable systems for specified life cycle cost

A new procedure for design for optimum reliability is given using a maximum life cycle cost constraint. Various life cycle cost vs reliability models are used for the purpose. The problem is treated for a series reliability structure. A numerical example is given to illustrate the procedure. The work establishes a firm quantitative footing for optimum life cycle cost design of reliable systems. In a sense it is revolutionary in the design-to-cost philosophy so often encountered in reliability design.     

Establishment of traceability for strain measuring data acquisition system in terms of voltage

This paper emphasizes on establishment of traceability for the strain measuring data acquisition system in terms of voltage. If this amplifier’s output voltage is not calibrated then traceability chain breaks. To complete the traceability chain, the amplifier’s output voltage has been calibrated for corresponding strain. The sensitivity is calculated using calibration results and further used to feed in data acquisition system to display the result in terms of force/strain.     

Optimal design of wing structures with substructuring

An iterative method for optimal design of large scale structures that incorporates the concept of substructuring is extensively applied to wing-type structures to demonstrate its generality, effectiveness and efficiency. Optimum designs for several wing-type structures are obtained and compared with results available in the literature. It is shown that considerable efficiencies can be achieved by integration of the substructuring concept into a structural optimization algorithm.     

Mean Time to System Failure for a 4-Unit Redundant Repairable System

The mean time-to-system-failure is derived for a system with 4-identical components, each of which has a constant failure rate and unspecified repair rate.     

Modification to the reduction technique of Thomas Case for obtaining a simplified reliability expression

A modification has been suggested to the reduction technique of Thomas Case [1], whereby it is easier to reduce less number-of-failure terms rather than more number-of-success terms.