DEVELOPMENT OF A DESIGN METHOD TO REDUCE CHANGE PROPAGATION EFFECTS

ABSTRACT This dissertation presents a design method to reduce engineering changes caused due to change propagation effect. The method helps designers to systematically plan a verification, validation, and test (VV&T) plan. The rationale behind such a method is founded on a well-accepted principle that a robust validation plan can reduce design changes. However, such method has not yet been developed in mechanical engineering domain, so a method from software engineering has been adopted and extended to address the limitations in the existing design evaluation tools. Tools extensively used in industry, such as FMEA, and in academia have been reviewed to determine if they can identify different propagation pathways including variant, behavior, organization, and geometric pathways. As a result, it is found that variant and organizational pathways are not identified in any of these tools -- propagation in these pathways have caused major product failure in commercial vehicle and automatic fire sprinkler manufacturing industries. A seven-step VV&T method is proposed to address the aforementioned gap in which each step is tailored to suit mechanical engineering needs. The major contribution is developing the construct to identify variant and organization pathways and a prescriptive method. It has been validated in a leading commercial vehicle manufacturer, one of the passenger car manufacturing giants, and an automatic fire sprinkler manufacturer. The results from these three companies indicate the proposed VV&T method enables designers to identify variant and organizational pathways and evaluate them, which in turn can reduce design changes due to propagation effects. Objective evidence obtained from the fire sprinkler manufacturing company supports this claim. \u27If we know what assembly combination to test with, testing is not a problem...and if it can prevent a failure of this magnitude --I think this method can --it can be extremely beneficial...\u27 - Project engineer, commercial vehicle manufacture

Life style characteristics of hospital paramedical healthcare professionals: a study from a tertiary care hospital, Pondicherry

Background: Life style is linked with future cardiovascular diseases. The aim of the work was to study the life style characteristics of hospital paramedical healthcare professionals.Methods: Paramedical professionals working in Aaruapadai veedu medical college and hospital were taken up for the study. The study was done as a cross sectional study using a pretested questionnaire method. Age, height, weight, waist circumference, diet pattern, physical activity, sleep and yoga pattern in all the hospital paramedical professionals were collected and studied.Results: Of the total one hundred hospital paramedical professionals, there were 90 female paramedical professionals. Among the female paramedical professionals, there were 69 of age less than 30years. Normal body mass index of less than 25 was seen (56) 62% of female paramedical professionals. Nine paramedical professionals had abdominal obesity. Of the total 10 male paramedical professionals 6 (60%) were taking food at improper time. Seven male and 58 female paramedical professionals did not do any form of exercise. A total of 84 female paramedical professionals were taking carbohydrate rich diet. Nineteen female paramedical professionals were doing regular exercise and three paramedical professionals were doing yoga. Eighty-five female paramedical professionals had refreshing normal sleep.Conclusions: Hospital paramedical healthcare professionals had a poor physical activity and diet pattern. The prevalence of abdominal obesity was less in paramedical professionals

Asymmetric somatic plant hybridization : status and applications

To create asymmetric somatic hybrids, the genome of the so-called donor protoplast is fragmented prior to protoplast fusion. As a result, only a limited amount of the donor genome is transferred to the fusion product. This technique can circumvent some commonly observed problems related to symmetric fusion and offers a practical breeding tool for asexual hybridization. Genomes are typically fragmented by irradiation, microprotoplast production or application of metabolic inhibitors such as iodoacetamide. Irradiation and microprotoplast production fragment the nuclear genome, whereas iodoacetamide inactivates the cytoplasmic genome. It can therefore be used to introduce cytoplasmic male ste- rility, an important practical application. For hybrid verification and genome characterization, molecular markers and cytogenetic techniques are applied. This review highlights and discusses progress made during the last decade in sper- matophytes asymmetric protoplast fusion

Reasons for Change Propagation: a case study in an automotive OEM

This paper focuses on identifying the reasons for change propagation during the production phase of the product life cycle. Unlike the traditional change propagation study where the focus is within the product, this study is focused to understand the propagation effects of change on other functional silos in the manufacturing firm. First, the reasons for the changes are identified using archival analysis through which it is found that 77.0 % of changes are due to internal reasons while 23.0 % are external. Second, these changes are distinguished into genesis, and propagated changes using a matrix-based modeling approach from which the reasons for propagation are identified. It is inferred that 32.4 % of the total changes are due to propagated changes such as inventory issues, manufacturing issues, and design error rectification. The majority of reasons for these propagated changes include document error rectification such as BOM error, drawing error, incorrect introduction date in engineering change note, and design error rectification such as design limitations. The findings indicate nearly one-third of time spent by the engineers can be reduced by developing appropriate controls during the change release process

Predicting Requirement Change Propagation Using Higher Order Design Structure Matrices: An Industry Case Study

This research examines higher order design structure matrices as requirements change modelling tools to predict requirement change propagation through two large-scale industry design projects. Due to the iterative nature of design, requirements will evolve and change. Changes in requirements can propagate to other requirements on different subsystems leading to possible increases in the project cost and lead-time. Predicting these requirement changes enables the designers to foresee unanticipated changes and maximises the probability for the project\u27s success. These studies reveal that second-order relationships are influential in predicting requirement change propagation. Unforeseen propagation occurring in first-order form was rare, rather it was occurring in second order. Modelling requirements change exposes these secondary relationships early in the engineering change (EC) definition process, thereby enhancing the decision-making process and augmenting cost estimation. A modelling tool, such as that proposed in this paper, can provide the designer insight into the requirements which may be affected before approving an EC

Antifungal activity of mangrove rhizobacterium Pseudomonas aeruginosa against certain phytopathogenic fungi and its growth characterization

Antimicrobial substances are widespread and they are likely to play an important protective role. Marine bacterium has been recognized as producer of important antimicrobial substances which has an exceedingly bright future in the discovery of life saving drugs. The present study was carried out to screen the antifungal activity of mangrove rhizobacteria against certain phyto pathogens from Manakudi estuary, Kanyakumari District, Tamilnadu. Around 20 colonies obtained in Zobell marine agar plates were screened for antifungal traits. Among the 20 isolates, the candidate bacterial isolate exhibited good anti fungal ability. Identification of strains was carried out and confirmed by cultural, biochemical and 16S rDNA sequences. The potent strain was identified as Pseudomonas aeruginosa. Various process factors such as different pH, temperature, carbon and nitrogen sources and NaCl were tested for the bacterial growth in static and shaking conditions. The isolated Pseudomonas aeruginosa possesed a variety of promising properties that favoured as a better biocontrol agent. In the present investigation antifungal activity of the mangrove isolate was tested against common pathogens like Penicillium sp., Candida sp., Aspergillus sp., Aspergillus fumigatus, Aspergillus flavus, Pescalotionbsis sp., Fusarium oxysporum and Glomerella cinculata. The candidate bacterium showed inhibitory action to the tested fungal pathogens except Fusarium oxysporum and Glomerella cinculata.