An Integrated Modeling Approach for Predicting Process Maps of Residual Stress and Distortion in a Laser Weld: A Combined CFD–FE Methodology

Laser welding has become an important joining methodology within a number of industries for the structural joining of metallic parts. It offers a high power density welding capability which is desirable for deep weld sections, but is equally suited to performing thinner welded joints with sensible amendments to key process variables. However, as with any welding process, the introduction of severe thermal gradients at the weld line will inevitably lead to process-induced residual stress formation and distortions. Finite element (FE) predictions for weld simulation have been made within academia and industrial research for a number of years, although given the fluid nature of the molten weld pool, FE methodologies have limited capabilities. An improvement upon this established method would be to incorporate a computational fluid dynamics (CFD) model formulation prior to the FE model, to predict the weld pool shape and fluid flow, such that details can be fed into FE from CFD as a starting condition. The key outputs of residual stress and distortions predicted by the FE model can then be monitored against the process variables input to the model. Further, a link between the thermal results and the microstructural properties is of interest. Therefore, an empirical relationship between lamellar spacing and the cooling rate was developed and used to make predictions about the lamellar spacing for welds of different process parameters. Processing parameter combinations that lead to regions of high residual stress formation and high distortion have been determined, and the impact of processing parameters upon the predicted lamellar spacing has been presented

Shock wave lithotripsy as a primary modality for treating upper ureteric stones: A 10-year experience

Aims and Objectives: Shock wave lithotripsy (SWL) has been recommended as a first-line treatment for upper ureteric calculi in several studies with a success rate of 80-90%. Our aim is to present our retrospective data of treatment of upper ureteric stones with SWL as primary modality over a 10-year period and evaluate the factors affecting fragmentation and clearance. Materials and Methods: From February 1997 to March 2007, 846 patients with upper ureteric stones were treated with SWL as the primary modality. Age: 9-69 years, 546 males and 300 females, stone size: 7-22 mm. Pyuria in 132/846 with clinical infection 40/132, pre-SWL JJ stenting: 40/846 and anesthesia in 41/846 patients. Duration of symptoms: < 4 weeks- 780/846,> 4 weeks- 66/846. Stone size: < 1 cm- 513/846,> 1 cm-333/846. Workup: X-Ray KUB, Urine and Uro-USG. Intravenous urogram (IVU): 130/846. Intraoperative (C-arm) fluoroscopic imaging was used. Presentation: colic-801/846, incidental-45/846. Criteria for clearance: symptomatic relief, X-ray and USG confirmation. Results: Clearance rate: < 1cm- 95.91% (492/513),> 1 cm- 85.29% (284/333). Overall clearance rate: 91.73% (776/846). No clearance: 70/846 (8.27 %). In these, 59/70 underwent ureteroscopy, 8/70 percutaneous nephrolithotomy and 3/70 open ureterolithotomy for clearance. Post SWL complications were seen in 25 (3%) cases with septicemia in nine and stein strasse in 16 cases. Duration of symptoms < 4 weeks - 93.7% success (731/780),> 4 weeks - 68.1% (45/66). Non-stented - 92% (744/806) success. Stented group-80% (32/40). Conclusions: Best results with SWL as monotherapy for upper ureteric stones are achieved when stones are less than 1 cm in size, of short duration history and without indwelling stents. Overall success rate - 91.73%

Prospective Randomised Controlled Trial Comparing Sub-Epididymal Orchiectomy Versus Conventional Orchiectomy in Metastatic Carcinoma of Prostate

Androgen blockade (surgical or medical castration) is a standard procedure for patients with metastatic carcinoma prostate. Sub-epididymal orchiectomy involves removal of testis leaving behind epididymis. This epididymal stump over a period gives a pseudo testicular feel within the scrotum. We present a prospective randomized study to assess the functional utility of this procedure and compare it with total orchiectomy in terms of achieving castrate levels. From July 2005–Jan 2008, 60 patients with metastatic carcinoma prostate were alternately randomised and allotted to two groups, 30 underwent sub-epididymal orchiectomy (group A) and remaining 30 (group B) underwent total orchiectomy. Age: 56–80 years. Serum PSA: 55–268 ng/ml. Preoperative serum testosterone: Group A—300–650 ng/ml and group B—320–640 ng/ml. Postoperative serum testosterone: group A—2–18 ng\ml and group B—7–15 ng\ml on day 7 after surgery. Operating time—26–40 mins for group A and 20–34 mins for group B. Follow up—6 weeks and 3 months. At 3 months patients were asked to grade appearance of scrotum for asthetic value on a scale of 1–100 using visual analogue score. Postoperative serum testosterone reached castrate levels in seven days (both groups). Duration of surgery in both groups was comparable. Complications—wound infection in 1 patient (group A) & 1 scrotal hematoma (group B). Satisfaction score for group A (83.5 ± 9.7) was significantly (p < 0.05) better (95%CI—18.58–28.42), compared to that of group B (60 ± 9.4) by using‘t’ test. Sub epididymal orchiectomy is comparable to total orchiectomy in terms of achieving castrate levels with similar operating time. It has significant advantage in terms of mental satisfaction to patients. It is a simple and safe procedure that can be conveniently performed in an outpatient clinic setting using pure local anaesthesia