Mechanical Engineering

The entire mankind is facing many challenges like energy sustainability, environmental problems and rising costs of petroleum fuel. Biodiesel has several advantages among other new renewable alternative fuel in terms of availability, performance and emission. In this paper a waste vegetable oil biodiesel and their performance evaluation of WVBD05, WVBD10, WVBD20 and WVBD40 has been done. The specific fuel consumption of WVBD blends is lower than that of petroleum diesel and among all WVBD05, the WVBD40 has highest BSFC but 4% lower than petroleum diesel. The maximum brake thermal efficiencies were obtained for WVBD40, which were 8% higher than that of diesel. Diesel engine make Kirlosker TV1 has been run successfully on biodiesel and its blends without any engine modifications. Waste vegetable oil, bio-diesel gave the performance nearer to that of petroleum based diesel, making it a promising renewable source for the diesel engines.

The ball indentation technique based on deforming a material with a spherical indenter is an useful non-destructive tool for evaluating mechanical properties from a very small volume of material. In this work, the indentation test carried out using a 1.0mm diameter tungsten carbide ball to penetration depths of around 100–200μm is modeled using finite element (FE) method and analyzed for

Electrostatically actuated nanotubes and nanowires have many promising applications as nanoswitches, ultra sensitive sensors and signal processing elements. These devices can be modelled as slender beams with circular cross-section. In this paper, effects of residual stress on static and dynamic characteristics of a cylindrical nanobeam are presented. Galerkin based multi-modal reduced order model technique has been used to solve the governing differential equation. The equation has also been solved numerically by collocation method for verification of the results. The effects of higher modes in reduced order modelling have been investigated. The analysis shows that the residual stress significantly influence the static and dynamic characteristics of the nanobeam. In particular, the results show that resonating frequency tunability increases significantly under the presence of compressive residual stress. In addition, an inherent resonating frequency stability mechanism under temperature variation in nanobeam resonators has also been explored.

In-plane driven nanowire oscillators are susceptible to undergoing planar to whirling motion transition due to coupling between flexural modes of vibration. This letter reports analytical modeling of initiation of whirling motion of an electrostatically actuated nanowire oscillator which is pre-deflected by applied DC voltage. A nonlinear coupled oscillator problem has been formulated and solved using second-order averaging method. Planar to whirling motion transition has been investigated by studying bifurcation diagrams. We have quantified the effect of DC voltage on nature of whirling dynamics of the nanowire oscillator.

We study the nonlinear coupling between orthogonal flexural modes of doubly clamped InAs nanowire resonators. The two orthogonal modes are formed by the symmetry breaking and lifting of degeneracy of the fundamental mode. The presence of a Duffing nonlinearity emerges when a mode is driven to large amplitudes. In this regime the modes are coupled due to the tension induced from the large amplitude of oscillations and is reflected in the hysteretic response of the mode that is not strongly driven. We study the driven-driven response of the mechanical modes to elucidate the role of nonlinear mode coupling in such mechanical resonators. The dynamics of the coupled modes studied here could prove useful in technological applications such as nanowire based vectorial force sensing.

Introduction and Objectives: We evaluated to compare the efficacy of urine cytology, NMP22, FISH in bladder cancer. Material and Methods: Washing urine samples of 156 patients were evaluated for detection of bladder cancer. A total of 156 patients were divided into 3 groups. In Group 1 were 106 patients with bladder cancer; in group 2 were 30 patients with BPH patients who underwent TURP without bladder cancer; and in group 3 were patient with gross hematuria without bladder cancer. The sensitivity and specificity of cytology, NMP22, FISH were compared. NMP22 positivity was defined as more than 10U/ml. FISH was used with the UroVysion® and FISH positivity was defined as more than 2 abnormal urothelial cells with an abnormal signal of any out of 4 probes. Results: The overall sensitivity of urine cytology, NMP22, FISH was 60.4%, 75.5% and 84.9%, respectively (pϽ0.001). The overall specificity of cytology, NMP22, FISH was 96.7%, 83.3% and 93.3%, respectively (pϭ0.168). But in group 3, the false positive rates of cytology, NMP22, FISH was 20.0%, 55.0% and 10.0%, respectively. In gross hematuria patients, the false positive rates of NMP22 was significantly higher than cytology and FISH (pϭ0.004). The sensitivity of cytology, NMP22, FISH in low grade bladder cancer patients was 25.9%, 51.9% and 77.8%, respectively, and in pTa-1 bladder cancer patients, 40.6%, 65.6% and 78.1%, respectively. In low grade or in pTa-1 patients, the sensitivity of three diagnostic tools was different significantly (low grade; pϽ0.001, pTa-1; pϽ0.001). Conclusions: FISH is more sensitive than urine cytology. So it can be used as a diagnostic tool for detection of primary and recurrent bladder cancer. In this study, because NMP22 was affected by gross hematuria, it has a limitation for screening of bladder cancer, but it can be used for follow up of bladder cancer.

Isolated high grade pancreatic injury is rare after blunt abdominal trauma. It is a rare entity to appreciate intra-operatively and a high index of suspicion should always be kept in mind to reach the diagnosis. We are presenting our experience of four cases with moderate to high grade isolated pancreatic injury which were managed in a lesser aggressive approach and had an uneventful outcome.

Hydatid cyst rupture into abdomen is a serious complication in cystic hydatid disease of liver. Both microscopic or macroscopic rupture can occur and it is fatal without surgery. It is primarily caused by tapeworm (ECHINOCOCCUS GRANULOSUS) and occurs worldwide with an incidence of 200/100,000in endemic areas. This is a case of 28 yr. female presenting with sudden onset pain abdomen since 4 days. Abdominal ultrasonography demonstrates ruptured hepatic hydatid cyst with free peritoneal fluid. She was managed in emergency operation theatre due to her clinical condition and exploratory laparotomy with omentopexy and toileting were done after fluid resuscitation, antihistaminic and corticosteroid treatment. Postoperatively she received antihelminthic treatment with Albendazol. She made a good recovery following surgery.

Introduction: Conventional modalities used to treat varicose veins with incompetent perforators and subsequent stasis ulceration have proved to be effective, however there are associated morbidities, such as postoperative pain, limited mobility, wound infection and dehiscence. Recent advances have been made in minimally invasive vein surgery techniques to decrease operative morbidity, number and size of incisions, recovery time, and operative time. Methods: A prospective study of 21 patients of varicose veins with incompetent perforators undergoing subfascial endoscopic perforator vein surgery (SEPS) using harmonic scalpel was designed and various parameters were studied. Results: All ulcers healed in 8 weeks with no recurrence in 11.9 months follow-up period. One case of wound infection and each saphenous nerve neuropraxia were the only postoperative complications noted. Use of ultrasonic scalpel in SEPS is technically feasible, causes less tissue damage as it generates a low thermal effect, and is associated with minimal morbidity.

A 24-year-old lady presented with left flank pain of 3 months duration. She had stigmata of tuberous sclerosis complex in the form of angiofibromas on face, ash-leaf macules on back and right upper limb and shagreen patches over back. Computed tomography scan of the abdomen showed 6.5 cm × 5.0 cm × 4.4 cm lobulated intensely enhancing exophytic mass lesion in mid pole of left kidney with significant para-aortic lymphadenopathy with no evidence of fat in the mass. She underwent radical left nephrectomy with a provisional diagnosis of renal cell carcinoma. Histopathological examination showed multicenteric angiomyolipoma involving kidney and para-aortic lymph nodes. This case report underscores the need for further research to differentiate fat-poor angiomyolipoma and lymphadenopathy from renal cell carcinoma.

Background: Invasive colonic amoebiasis presents primarily with dysentery; colonic perforation occurs rarely. Cases of amoebic colonic perforations have been reported sporadically over the past 20 years. Methods: A retrospective study was done in the surgical unit of a tertiary care hospital in North India. The case records of those patients were reviewed who underwent exploratory laparotomy from January 2011 to September 2012 and were diagnosed with amoebic colonic perforation on histopathological examination. Details concerning the clinical presentation, investigations, intraoperative findings, operative procedures, and postoperative outcomes were retrieved. Results: Amongst, a total of 186 emergency exploratory laparotomies carried out during the study , 15 patients of amoebic colonic perforation were identified. The median age of the patients was 42 years (IQR 32.0-58.0) and the male to female ratio was 13:2. Previous history of colitis was present in only 1 patient. The preoperative diagnosis was perforation peritonitis in 12 patients; and intussusception, intestinal obstruction and ruptured liver abscess in 1 patient each. Ten patients had single perforation while 5 had multiple colonic perforations. All the patients except one had perforations in the right colon. Bowel resection was performed depending upon the site and extent of the colon involved-right hemicolectomy (8), limited ileocolic resection (6) and sigmoidectomy (1). Bowel continuity could be restored only in 2 of the 15 patients and a stoma was constructed in the remaining 13 patients. The overall mortality rate was found to be 40% (6/15). Conclusion: Amoebic colonic perforation is associated with unusually high mortality.