Jesa H. Kreiner

Energy Efficiency of Industrial Oils

Lubricants influence energy efficiency mainly through reducing energy losses, which include churning losses and friction losses in hydrodynamic, elastohydrodynamic and boundary lubrication regimes. The total energy loss depends on lubricant viscosity and chemical composition. Different sources of lubricant-related power losses in industrial systems are described. The dependence of churning and friction losses on oil properties is analyzed. Viscosity shear-thinning and pressure-thickening effects and their dependence on base oil and viscosity index improver chemical composition are examined. The role of pressure-viscosity relationships is emphasized. Some aspects of oil compressibility and viscoelasticity are discussed in regard to oil energy efficiency. The mechanism and role of friction modifiers in industrial oil formulations are described. Significant savings in machinery energy consumption can be achieved by using energy-efficient lubricants. Methods for improving industrial lubricant energy efficienc...

Development of improved and efficient traffic flow model

Abstract The paper deals with development of efficient and improved traffic flow model to predict the space mean speed, ūs, in terms of the mean free flow speed, uf, and the density, k. The Greenberg model (which is based on fluid-flow analogy concept)satisfies the boundary condition only at jam density, kj. It violates the boundary condition at zero density, k, in the sense that it can only be attained at infinitely high speeds according to Khisty and Lall [1] and Papacostas and Prevedouros [2]. The intent of this research work is specifically to arrive at an improved version of Greenberg model (CSUF model). The CSUF model will be accomplished by expansion of natural log expression in Greenberg expression and considering only linear terms. The correlation coefficient will then be calculated. Existing experimental results will be used to validate the model. These results will then be compared with the results already existing in the literature from the Greenberg model as well as the Underwood and Eddie model.

A computer aided technique for shaft design through monte carlo simulation

Abstract The paper predicts the probability of failure of shafts subjected to reverse bending during the process of transfer of power. Since reliability and probability of failure are complementary to each other, the safety levels are calculated in terms of reliability factors. The shafts considered in this study are subjected to tension, compression, bending or torsional loads acting singly or in combination with one another. The static and fatigue strength become important design considerations in cases like these as the shafts are subjected to static stresses, completely reversed stresses and repeated cyclic stresses, all acting at the same time. All this is considered with the input parameters being probabilistic, as in reality, these are supposed to have some variations. Finally, theoretical equations are developed for the output coefficient of variation of shaft diameter as a function of the coefficient of variation of input parameter for various design theories existing in literature. The results are then checked with those obtained by Monte Carlo simulation. Excellent correlation was obtained between the two sets of results.

Total quality engineering, failure analysis and stochastic process evaluation of engineering project alternatives

The interaction of technical ergonomic and product liability concepts within total quality engineering and management frameworks are evaluated. Risk management and insurance industry paradigms are examined as affecting value engineering and decision-making under uncertainty analysis. Joel Barkers Future Edge success paradigms are extended to risk analysis and ergonomics to achieve total quality and robustness. Examination of stochastic evaluation of engineered structures for life-cycle costing used with consideration of project alternatives is emphasized, and is an extension of work done by the authors in the area of legal liability and technical insurance as related to engineering structures. Also considered are factors for safety and risk and project alternatives. Results show that for a complete assessment of project alternatives, concurrent interdisciplinary engineering methods are required.<<ETX>>

Performance Analysis of a Space Shuttle External Tank Attach Ring using Probabilistic Principles

Abstract This work deals with performance analysis of an external tank attach ring of a space shuttle. The shuttle consists of the orbiter and the main engines along with the solid rocket boosters, external tank (ET), and external tank attachment (ETA) ring. The study discussed in this paper is restricted solely to the ETA. Performance analysis in the traditional deterministic sense involves calculation of margin of safety values for yield and ultimate allowable stresses. Performance analysis using probabilistic principles uses probabilistic margins of safety (PMS). These values are determined for various parts of ETA ring cross-sections and a comparison is made between the two sets of results. This study also indicates that there is a good built-in margin of safety in the ETA ring components as indicated by high PMS values, and it further includes the existing results for membrane and grid forces of ETA ring after incorporating the uncertainty of these variables based on the existing data in the literature and past experience at NASA.

Safety analysis of tension elements using various reliability methods

This work is an extension of the earlier research done by the authors in this area (Putcha and Kreiner, 1993) wherein these principles were applied to a steel beam with an external moment. The main methods used for estimation of reliability in the previous as well as the present research are: the First Order Second Moment (FOSM) method, the Advanced First Order Second Moment (AFOSM) and the Point Estimate Method (PEM). For each method, the reliability of the tension element is calculated. The safety indices (/spl beta/) are calculated for the various types of probabilistic combinations of resistance and load. Results obtained by these three methods are compared to one another. Subsequently, relevant conclusions are drawn.