Using Taguchi method to optimize welding pool of dissimilar laser welded components

In the present work CO2 continuous laser welding process was successfully applied and optimized for joining a dissimilar AISI 316 stainless steel and AISI 1009 low carbon steel plates. Laser power, welding speed, and defocusing distance combinations were carefully selected with the objective of producing welded joint with complete penetration, minimum fusion zone size and acceptable welding profile. Fusion zone area and shape of dissimilar austenitic stainless steel with ferritic low carbon steel were evaluated as a function of the selected laser welding parameters. Taguchi approach was used as statistical design of experiment (DOE) technique for optimizing the selected welding parameters in terms of minimizing the fusion zone. Mathematical models were developed to describe the influence of the selected parameters on the fusion zone area and shape, to predict its value within the limits of the variables being studied. The result indicates that the developed models can predict the responses satisfactorily

Fish play Minority Game as humans do

Previous computer simulations of the Minority Game (MG) have shown that the average agent number in the winning group (i.e., the minority group) had a maximal value such that the global gain was also maximal when an optimal amount of information was available to all agents . This property was further examined and its connection to financial markets has also been discussed . Here we report the results of an unprecedented real MG played by university staff members who clicked one of two identical buttons (A and B) on a computer screen while clocking in or out of work. We recorded the number of people who clicked button A for 1288 games, beginning on April 21, 2008 and ending on October 31, 2010, and calculated the variance among the people who clicked A as a function of time. We find that variance per person decreases to a minimum and rises to a value close to 1/4 which is the expected value when agents click buttons randomly. Our results are consistent with previous simulation results for the theoretical MG and suggest that our agents had employed more information for their strategies as their experience playing the game grew. We also carried out another experiment in which we forced 101 fish to enter one of the two symmetric chambers (A and B). We repeated the fish experiment 500 times and found that the variance of the number of fish that entered chamber A also decreased to a minimum and then increased to a saturated value, suggesting that fish have memory and can employ more strategies when facing the same situation again and again

MS

thesisThe Electrocardiogram (ECG) Department at the Latter-Day-Saints Hospital has used a computerized ECG system for more than 15 years. In this automated system, all the ECG data were analyzed by a set of Health Evaluation Logic Processing (HELP) frames and the resulting interpretations were stored in the patient data base. In 1987, the Department replaced this system with the Marquette Universal System for Electrocardiography (MUSE). As a stand alone system, MUSE stores all its ECG interpretations in its own data base. Since the HELP system serves as the information center for the Hospital, it is necessary to establish an interface between the HELP and the MUSE systems so that the MUSE ECG interpretations can be stored in HELP and become available to the clinical personnel. To integrate the MUSE system to HELP, one first faces the challenge of terminology difference between these two systems. According to the degree of compatibility among the terms used, there exist three categories of the MUSE interpretations. Different strategies were used in defining the Pointer to TeXT (PTXT) codes for these three categories of MUSE interpretations. In the process of constituting the PTXT representations for the MUSE system, care was taken to avoid duplicating existing codes in the HELP data dictionary. The second issue in interfacing the MUSE system to HELP lies in understanding the MUSE statements. A MUSE statement may contain different interpretations. Therefore, if a MUSE statement is to be stored in the HELP system, the interpretations constituting this statement must be understood so that their corresponding PTXT codes can be stored. In order to do this, a parsing algorithm was designed to detect different interpretations used in a statement and store their PTXT representations to HELP. After the implementation of the interface software, it was found that the software was constantly ready to capture the MUSE data into the HELP system. In addition, all the MUSE EGG statements, after being processed by the parsing algorithm, had been transferred to semantically corresponding interpretations. These interpretations were stored as patient records and were available to the reviewing physicians throughout LDS Hospital

A Quality-based Security Enhancement Procedure to Improve E-Commerce security

E-commerce is an important product in the internet fever. However, the network intrusion and security vulnerabilities have continued to threaten the e-commerce operation and user privacy. How to improve security of e-commerce has become a topic worthy exploration. In this paper, based on security testing and repair, proposes a Software Security Enhancement Procedure (SSEP for short). In addition, for assuring SSEP operation quality, proposes a set of Software Security Enhancement Process Quality Measurement (SSEPQM for short) model. Applying SSEPQM model, the defects of security improvement process can be identified and revised. So the security of e-commerce can be enhanced effective and continuous

Partially Balanced Incomplete Block Designs

In balanced incomplete block designs, each pair of treatments is compared with equal precision, and each treatment is paired with every other treatment an equal number of times with in a common block; A is a constant for all treatments. There is one associate class for each treatment in balanced incomplete block designs. These are the most important balanced incomplete block designs, but the need sometimes arises for others; either because no suitable balanced incomplete block design exists, or because, for example, it is necessary to make some comparisons more precisely than others. We can see balanced incomplete block designs form that special case of partially balanced designs in which there is one associate class for each treatment. In this paper, the author will discuss the partially balanced incomplete block design with two associate classes

Control of welding residual stress for dissimilar laser welded materials

The most common problem of welding dissimilar metals (DMWs) with respect to residual stresses is the differences in the coefficient of thermal expansion and heat conductivity of the two welded metals. In the present work, a CO2 continuous laser welding process was successfully applied and optimized for joining a dissimilar AISI 316 stainless steel and low carbon steel plates. The Taguchi approach with three factors (selected welding parameters) at five levels each (L3-25) was applied to find out the optimum levels of welding speed, laser power and focal position for CO2 keyhole laser welding of dissimilar butt weld. The responses outputs were the residual stresses at different depth in the heat affected zone (HAZ). The Hole-Drilling Method technique was applied to measure the residual stress of dissimilar welded components. The results were analysed using analysis of variances (ANOVA) and signal-to-noise ratios (S/N) for an effective parameters combination. Statistical models were developed to describe the influence of the input parameters on the residual stress at different specimen levels; to predict there value within the limits of the variables under investigation. The result indicates that the developed models can predict the responses satisfactorily

Partial cancellation of shaking force harmonics by cam modification

An optimization procedure for minimizing the shaking force harmonics of machinery is described. Because of constraints imposed by the specification, optimization is unlikely to make any significant reduction in the fundamental, machine frequency, term of the shaking force. That term, normally the largest, must be substantially reduced by other means for the procedure described here to be cost effective. Earlier work describing methods of reducing the fundamental term are cited. An extrusion press machine incorporating two planar mechanisms, one crank driven and one cam driven, provides an example. Two designs of the cam-driven mechanism, referred to here as cams 1 and 2, are in use in installed extrusion press machines. Harmonic analysis of the shaking force as a function of time shows that cam 2 produces smaller amplitudes of shaking force harmonics. The ten variables used in the optimization process are the amplitudes and angles of the first five terms of a trigonometric series defining the acceleration of a reciprocating mass driven by a hypothetical third cam, cam 3, which is similar to cam 2 but stripped of all harmonics of order higher than the fifth. The objective function is the sum of the amplitudes of the horizontal components of the second to fifth shaking force harmonics on the machine as a consequence of accelerations of the moving parts of both mechanisms. Several equality and inequality constraints must be met. For the extrusion press machine the result is a reduction in the amplitudes that would be created if cam 3 were to be used by approximately 10, 75, 65 and 100 per cent respectively. The improvement over cam 1 is greater. The procedure is particularly suited as a retrofit measure where the number of installed machines is large in relation to the future rate of production of new machines: a cam that has been removed from one machine can be re-cut for use on another machine