Approach Tolerance in the Assemblies of Evolutionary Hybrid Prototypes

A new answer is proposed to replace the traditional “one shot” prototype (manufactured in one piece with one process): the hybrid rapid prototype. It is used to highly reduce time, cost and increase reactivity during the development times of new products. The part is decomposed in several components which can quickly be changed and can be manufactured with a process the most adapted. The main objective of the presented method is to propose an available technological assembly between the different components of the part in the respect of technological and topological function, and initial tolerance. Using a graph of representation, fuzzy logic and a tolerance point of view, some entities are associated with a CIA (Assembly Identity Card) in accordance with evolutionary and manufacturing analysis. This work will be illustrated by an industrial tooling for plastic injection.Mechanical Engineerin

Exploring Vacuum Casting Techniques for Micron and Submicron Features

A study of resolution limits in standard rapid prototyping vacuum cast molding processes and adaptation of this technique to reach submicron accuracy is proposed. Micro-fabrication technologies are used to fabricate micron and submicron high aspect-ratio patterns on the original parts. The molding of the original parts is optimized to allow replication of submicron features. In carefully exploring materials and surface treatments, cast parts are successfully replicated with submicron and high aspect ratio micron structures. These encouraging results enable the use of such processes for micro- and nano-systems applications and open the door to development and production of low cost, high resolution biochips.Mechanical Engineerin

Energy Utilization Analysis and Optimization of Corrective Insoles Manufactured by 3D Printing

The foot orthotic insole market is forecast to surpass a value of 3.6 billion USD by 2021. This vast industry continues to rely on foam milling and other subtractive methods of manufacturing, which have proven to be wasteful and inefficient. Leaps in digital manufacturing have enabled the technology to enter a plethora of industries, with the promise of increased customization accompanied with reduced waste generation. Despite boasting these valuable traits, the explosive proliferation of 3D printing in conjunction with mounting pressure to incorporate sustainable practices, means that research must be focused on maximizing the material and energy efficiency of the technology. This paper employs a Design of Experiments (DoE) approach for the optimization of two prefabricated insoles, adjusting percentage infill and layer height to obtain data regarding the effects of these parameters on print time, filament usage volume, and energy consumption. Key conclusions formed from the study were that infill density is the dominant factor effecting material consumption and power usage, whereas layer height has the greatest influence on production time. The data presented in this study has the potential to aid not only in the development of mass producible additive manufactured (AM) insoles, but also to advance the understanding of the environmental impact of AM technologies

Safety and effectiveness of bariatric surgery: Roux-en-Y gastric bypass is superior to gastric banding in the management of morbidly obese patients

<p>Abstract</p> <p>Background</p> <p>The use of bariatric surgery in the management of morbid obesity is rapidly increasing. The two most frequently performed procedures are laparoscopic Roux-en-Y bypass and laparoscopic gastric banding. The objective of this short overview is to provide a critical appraisal of the most relevant scientific evidence comparing laparoscopic gastric banding versus laparoscopic Roux-en-Y bypass in the treatment of morbidly obese patients.</p> <p>Results and discussion</p> <p>There is mounting and convincing evidence that laparoscopic gastric banding is suboptimal at best in the management of morbid obesity. Although short-term morbidity is low and hospital length of stay is short, the rates of long-term complications and band removals are high, and failure to lose weight after laparoscopic gastric banding is prevalent.</p> <p>Conclusion</p> <p>The placement of a gastric band appears to be a disservice to many morbidly obese patients and therefore, in the current culture of evidence based medicine, the prevalent use of laparoscopic gastric banding can no longer be justified. Based on the current scientific literature, the laparoscopic gastric bypass should be considered the treatment of choice in the management of morbidly obese patients.</p

Six Months of Balloon Treatment does Not Predict the Success of Gastric Banding

BACKGROUND: We studied whether weight loss by intragastric balloon would predict the outcome of subsequent gastric banding with regard to weight loss and BMI reduction. METHODS: A prospective cohort of patients with a body mass index (BMI)>40 kg/m(2) received an intragastric balloon for 6 months followed by laparoscopic adjustable gastric banding (LAGB). Successful balloon-induced weight loss was defined as > or =10% weight loss after 6 months. Successful surgical weight loss was defined as an additional 15% weight loss in the following 12 months. Patients were divided in group A, losing > or =10% of their initial weight with 6 months' balloon treatment, and group B, losing <10% of their initial weight. RESULTS: In 40 patients (32 female, 8 male; age 36.6 yr, range 26-54), the mean BMI decreased from 46.5 to 40.5 kg/m(2) (P <0.001) after 6 months of balloon treatment and to 35.2 kg/m(2) (P <0.001) 12 months after LAGB. Group A (25 patients) and group B (15 patients) had a significant difference in BMI decrease, 12.4 vs 9.0 kg/m(2) (P <0.05), after the total study duration of 18 months. However, there was no difference in BMI reduction (4.7 kg/m(2) vs 5.8 kg/m(2)) in the 12 months after LAGB. 6 patients in group A lost > or =10% of their starting weight during 6 months balloon treatment as well as > or =15% 12 months following LAGB. 6 patients in group B lost <10% of their starting weight after 6 months of BIB, but also lost > or =15% 12 months following LAGB. CONCLUSION: Intragastric balloon did not predict the success of subsequent LAG

Quality of life after bariatric surgery - a comparative study of laparoscopic banding vs. bypass

: Laparoscopic gastric banding and Roux-en-Y gastric bypass are widely used for the treatment of morbid obesity. The impact of these two procedures on health-related quality of life has not been analyzed in comparative studies. METHODS: A matched-pair analysis of a prospectively collected database was performed. Fifty-two consecutive patients with laparoscopic gastric bypass were randomly matched to fifty-two patients with laparoscopic gastric banding according to age, BMI, and gender. Quality of life was assessed using two standardized questionnaires (SF 36 and Moorehead-Ardelt II). RESULTS: Mean preoperative BMI was 45.7 kg/m(2) for the bypass patients and 45.3 kg/m(2) for the banding patients. Mean BMI after 3 years follow-up of was 30.4 kg/m(2) and 33.1 kg/m(2) (p = 0.036). In the SF 36 questionnaire, gastric bypass patients yielded a mean total score of 613 versus 607 points in the gastric banding group (p = 0.543), which is comparable to the normal population in Europe. In the Moorhead-Ardelt II questionnaire, the gastric bypass patients scored a mean total of 1.35 points and the gastric banding patients 1.28 points (p = 0.747). Of the patients, 97% with a gastric bypass and 83% with a gastric banding were satisfied with the result of the operation (p = 0.145). CONCLUSION: The patients after laparoscopic gastric bypass and laparoscopic gastric banding have a high level of satisfaction 3 years after the operation and have similar quality of life scores compared to the normal population. Quality of life indexes were not different between the two procedures and were independent of weight loss in successfully operated patients