Victor Zaloom

On the Resource Constrained Project Scheduling Problem

Abstract A procedure is presented for establishing lower bounds on the minimum schedule duration for resource constrained projects. This procedure consists of finding the smallest time which satisfies each of four lemmas which are established. The results of testing this procedure on a sample of SO simulated projects are summarized.

Cooling Suits, Physiological Response, and Task Performance in Hot Environments for the Power Industry

Heat stress on workers working outdoors in the power industry may result in fatigue and deterioration in task performance. This research collected and analyzed data on task performance of workers working indoors and outdoors with and without a cooling suit. The task performance was compared on the basis of heart rate, oxygen consumption, tympanic temperature, subjective responses, productivity, and error rates. Based on One-Way Analysis Of Variance (ANOVA) results, a significantly lower estimated working oxygen consumption was observed (p < .001) when the cooling suit was worn. The productivity was higher while workers wore the cooling suit as compared to no cooling suit (p = .011) whereas the error rates were significantly lower(p < .001). Also a significantly lower self-reported discomfort was observed in the neck and shoulders while working wearing the cooling suit (p = .004). This study concluded that wearing a cooling suit while working outdoors was associated with physiological benefits as well as improved task performance of the study participants.

Computer-Aided Link Analysis (CALA)

Abstract A system is presented to automate data capture and enhance currently available methods of performing link analysis. Link analysis is a method of analyzing a system based on the relationships (links) between its elements. Link analysis is used in many diverse applications, but is most effective in analyzing the arrangement of elements within physical systems such as the cockpit of an aircraft or the production or storage areas of a factory. An application of the Computer-Aided Link Analysis (CALA) system to the redesign of an office layout is presented to illustrate the versatility of the system.

A computer based training system for process safety management

Abstract The Process Safety Management (PSM) regulations as specified by the Occupational Safety and Health Administration (OSHA) in the code of federal regulations Chapter 29 Section 1910.119 (29 CFR 1910.119 ) requires employers to meet certain documentation and training requirements. A computer based system to meet both documentation and training requirement is proposed.

Bank funds management by goal programming

Abstract A goal programming model was developed which attempts to achieve a number of objectives normally desired in the banking industry. The model incorporates objectives relative to providing sufficient liquidity, minimizing risk, maintaining adequate levels of capital, minimizing the cost of capital, maximizing profit and providing reasonable dividends. The constraints on the model relate to pledged assets required by the government, required reserves and limits on certain balance sheet items. Model validation is accomplished by utilizing data obtained from a commercial bank. The data includes financial information for 1982–1984. The 1982 actual data is utilized by the model to project 1983 and 1984 conditions. These projected numbers are then compared with actual financial data to compare the models performance with results achieved by management without the use of the model. Total underachievement of several goals in banking is minimized within the limits of the actual decision environment.

A review of cost estimating for advanced composite materials applications

Abstract Four major cost models for estimating cost of components fabricated from advanced composite materials are reviewed. Prior to this review the term “advanced composite materials” is defined and a brief listing of some aerospace applications in the United States is presented.

Probability Analysis of Vessel Collisions and Groundings in Southeast Texas Waterways

The Sabine–Neches Waterway (SNWW) connects the Texas ports of Beaumont, Port Arthur, and Orange with the Gulf of Mexico. The SNWW can be divided into three navigation routes, although they share some channels. The first route is the waterway from the Neches River, north of the port of Beaumont, to the port of Port Arthur, and then to the Gulf of Mexico. The second route is a part of the Gulf Intracoastal Waterway (GIWW), west of Port Arthur, which extends east of the port of Orange. The third route is from the port of Orange to the Gulf of Mexico. The SNWW plays an important role in its support of the economic growth of southeast Texas. Safe navigation in narrow waterways is one of the most important concerns of maritime authorities and researchers, while collisions and groundings are two of the most common kinds of vessel accidents. In the study reported here, the grounding and collision analysis toolbox was employed to analyze the probabilities of collisions and groundings in multiple segments along the SNWW. The impacts of vessel traffic on the probabilities of collisions and groundings were studied, respectively. The high-risk zones of potential collisions or groundings were identified in the SNWW.

On the Proper Use of Compound Interest Factors—A Technical Note

Five of the seven factors in most common use for compound interest calculations involve a uniform series of payments (or receipts). These interest factors, for use when interest is compounded at discrete points in time, are commonly referred to as the uniform series present worth factor, the uniform series compound amount factor, the capital recovery factor, the sinking fund factor and the uniform series gradient conversion factor. The proper use of these five factors requires that the period of time between the compoundings of interest coincide with the period of time between the uniform payments. If the interest is compounded more frequently (assume by an integer number of times) than the payments, then the best way to apply the compound interest factors is to determine the effective interest rate between payments. If interest is compounded less frequently than the payments (assume there are an integer number of payment periods within each compounding period), the correct solution procedure is not well ...

Experimental Investigation of the Tool Wear and Tool Life in Micro Hard Milling

The objective of this project is to experimentally investigate the influence of Minimum Quantity Lubrication (MQL) on tool wear and tool life in micro hardmilling. The experiments were performed on stainless steel using uncoated WC micro-mill with the nominal diameter of 508 microns. The tool wear is characterized by the volume of the material loss at the tool tip. In order to reveal the progression of the tool wear, the worn tool was examined periodically under SEM after a fixed amount of workpiece material removal (1.25 mm3 or 5 slots in this study). The tool life was characterized as the amount of material removed, instead of the conventional cutting times. The feedrate and the spindle speed were fixed, and two levels of axial depth of cut (50 and 75 microns) were compared. The higher depth of cut leads to longer tool life. The machining performance under MQL is superior to the dry machining for both process conditions in terms of the tool life. The cutting forces in feed direction and the surface roughness at the bottom of the slots were also examined during the experiments. The magnitude of the machining forces showed cyclic pattern for both MQL and dry machining. The SEM images and the cutting force signals suggested that the dominant mode of the tool wear in micro-milling is edge chipping and abrasive wear at the tool tip. The loss of the micro-grain of WC at the cutting edge leads to edge chipping, which reduces the effective cutting diameter; the abrasive wear enlarge the edge radius, causing the cutting force increase. As the cutting edge radius reaches a certain dimension, the whole edge was stripped off, a new edge formed with a smaller edge radius, and the cycle restarts. Under MQL cutting conditions, three cycles were observed before tool failure, while under dry machining conditions, the tool only experienced two cycles before tool breakage. The surface roughness at the bottom of the slots improved significantly with the application of MQL for all levels of the tool wear. The surface roughness did not increase drastically as the tool wear increased. It reached a plateau after the tool wear went into gradual wear state. Further experiments and theoretical analysis will be pursued in the future to gain a deeper understanding of tool wear mechanism in micro-milling.Copyright

Multi-Objective Optimization for the Micro-Milling Process With Adaptive Data Modeling

This paper presents a multi-objective optimization study for the micro-milling process with adaptive data modeling based on the process simulation. A micro-milling machining process model was developed and verified through our previous study. Based on the model, a set of simulation data was generated from a factorial design. The data was converted into a surrogate model with adaptive data modeling method. The model has three input variables: axial depth of cut, feed rate and spindle speed. It has two conflictive objectives: minimization of surface location error (which affects surface accuracy) and minimization of total tooling cost. The surrogate model is used in a multi-objective optimization study to obtain the Pareto optimal sets of machining parameters. The visual display of the non-dominated solution frontier allows an engineer to select a preferred machining parameter in order to get a lowest cost solution given the requirement from tolerance and accuracy. The contribution of this study is to provide a streamlined methodology to identify the preferred best machining parameters for micro-milling.Copyright