This paper introduces a new and uniform method of Linear Programming optimization problems for both standard and non-standard cases. Using this method, all the linear programming (LPP) optimization problems can be solved using slack variables only by a simple transformation. Thus, it eliminates the use of surplus and artificial variables and the need to use the big M method. The efficacy of this method has been shown by few examples which gave same results using the traditional methods.

This paper proposes an innovative and efficient method for balancing an adaptive digital AC bridge employing a closed-loop control system to measure the impedance of passive networks. A neoteric method that uses Widrow-Hoff's least mean square (LMS) ...

This article deals with development of fault-trees for risk assessment of dam gates and associated operating equipment. The first part of the paper deals with background information leading to the selection of Lafitte Method as the preferred method for risk assessment. The article also discusses in detail the initiating events, consequential events, and the consequences, dealing with transient and persistent overtopping results of the sensitivity analysis along with a detailed list of various failure events, the associated failure modes and their cause/effect dealing with dam gates. Actual detailed fault-trees for dam gates and associated operating equipment are presented.

This paper deals with the development of a risk methodology of failed hardware components. This is important because it is not prudent to use hardware (that did not perform per specification) witho...

The paper will present the development of analysis tools for use in risk assessment of dam gates and associated operating equipment. The methodologies discussed will focus on using fault tree analysis of dam spillway system that concentrates on the failure of the dam gates and operational subsystems. Two different methods of pre-screening analysis will be presented and evaluated. The first method uses criticality analysis to rank each of the potential failure modes in a Failure Modes and Effects Analysis. The second method uses the traditional estimation of probabilities of failures in conjunction with importance ranking factors for the gate subsystems to estimate the probability of failure for overall gate system. Conclusions and recommendations will be made for each of the methods presented.

This article deals mainly with identification of a suitable method for time-dependent reliability and analysis of navigation structures based on a detailed literature review, application of the method to a miter gate, and comparison of results with the existing results in the the literature. The aspect of corrosion is considered in the study. This work is a continuation of the work on rolled steel sections reported by the authors at an international conference in Canada. Detailed computer programs in FORTRAN have been developed as part of this research study. It has been found that the existing results and the results of the present investigation compare very well.

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.

This paper deals with the calculation of failure bounds for navy wharves. A general reliability methodology for seismic loads is presented. A practical navy wharf problem is used as an example.

In this paper an attempt is made to make a statistical study of the accuracy of various equations for prediction of the ultimate stress of unbonded prestressed beams (f(ps)) suggested by different investigators in recent years. Comparison is made with the experimental results. Comparison is also made with ACI 318-89/92 code equations (18-4) and (18-5). Each equation is tested using the combined pool of all the experimental data used by these investigators.

The critical load of a frame is affected to a large extent by variations in the lengths and cross-sections of beams and columns and the strength of steel. Consequently, the deterministic critical load does not represent the true behaviour of the frame. In this paper, based on a rigorous probabilistic analysis, closed-form equations are derived between the coefficient of variation of the critical load of the frame and the corresponding dependent and independent variables. These are then checked with the results obtained using Monte Carlo simulation. The practical significance of these results vis-a-vis deterministic analysis is discussed.

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 (β) 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

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 Barker's 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

The authors deal with the application of probability principles to the bond behavior of fiber reinforced concrete. Specifically, reliability analysis of the experimental data of normal and high strength concrete is performed using the base parameters uav (average bond strength) and u'av (normalized average bond strength). The coefficient of variation of uav and u'av, obtained based on the experimental results, is compared with the corresponding values using the Monte Carlo simulation method and the partial derivative method. Also, a regression equation is developed between the response variable and other variables for the pullout load of the specimen

The authors deal with reliability analysis of the external tank attachment ring used as an interface between the external tank attach struts and solid rocket motor. It is part of the solid rocket booster and is a critical element of the Shuttle and hence, was chosen for the reliability study. The approach used here is to treat the material, geometric and load properties as probabilistic and use the corresponding deterministic functional relations for calculation of normal, shearing and principal stresses. No new finite element analysis calculations are made but the existing results for membrane and grid forces are utilized in the reliability calculations incorporating the uncertainty of these variables based on the existing data in the literature and past experience at NASA. The final comparison is made between the results of reliability analysis and the corresponding deterministic analysis in terms of probabilistic safety margin values.<>