IMPACT OF FRICTION COEFFICIENT VARIATION ON TEMPERATURE FIELD IN ROTARY FRICTION WELDING OF METALS – FEM STUDY

A mathematical model is presented for investigating the temperature field caused by the rotary friction welding of dissimilar metals. For this purpose, an axisymmetric, nonlinear, boundary value problem of heat conduction is formulated with allowance for the frictional heating of two cylindrical specimens of finite length made of Al 6061 aluminium alloy and 304 stainless steel. The thermo-physical properties of materials change with increasing temperature. It was assumed that the coefficient of friction does not depend on the temperature. The mechanism of heat generation due to friction on the contact surface with the temperature field of samples is considered. The boundary problem of heat conduction was reduced to the set of nonlinear ordinary differential equations at time t relative to the values of temperature T at the finite elements nodes. The numerical solution of the problem was obtained with the inverse 2nd order differentiation method implemented in COMSOL FEM system (finite element method), with time step ∆t=0.1 (s). The influence of various values of friction coefficient is presented

Effectiveness of laparoscopic sleeve gastrectomy and one anastomosis gastric bypass on the resolution of metabolic syndrome — a review

The main cause of the development of metabolic syndrome seems to be an imbalance of calorie intake and energy expenditure. However genetic and epigenetic factors, sedentary lifestyle, poor food quality, and disturbances in gut microbiota also play a major role. There is no single effective method of treatment for metabolic syndrome. Dietary therapy and an increase in physical activity along with pharmacological treatment are not fully effective to recommend them as a therapy for metabolic syndrome. Today, modern bariatric-metabolic procedures such as laparoscopic sleeve gastrectomy or single anastomosis gastric bypass give the best chances of successful resolution of metabolic syndrome

Pozaotrzewnowe, zmodyfikowane wytrzewienie tylne (radykalna ooforektomia typu II) jako część ultraradykalnej chirurgii raka jajnika – opis przypadku

Epithelial ovarian cancer remains to be the most deadly gynecologic cancer among the female population. Carcinogenesis and abdomen extension are the reasons why ovarian cancer is still examined in advances stages. Ovarian cancer frequent metastasizes to the uterus, rectosigmoid colon, and other pelvic structures by intraperitoneal seeding of tumor deposits, as well as direct extension. Multiple modalities of therapy are utilized in the management of the disease. Numerous medical trials and research programs have demonstrated the most important role of surgery in the treatment of this disease. A vast majority of authors are of the opinion that the surgical interventions have a major influence on the overall survival (OS) and progression free survival (PFS) in ovarian cancer cases. The paper presents a case of a 35-year-old woman diagnosed with advanced ovarian cancer who underwent modified posterior exenteration as a part of extensive cytoreductive surgery.Rak jajnika jest wciąż jedną z najczęstszych przyczyn zgonów na nowotwory złośliwe dotyczące narządów płciowych wśród kobiet. Karcinogeneza choroby, możliwość szerzenia się jej drogą wszczepów brzusznych sprawia, iż schorzenie to rozpoznawane jest często w zaawansowanych stadiach rozwoju (FIGO III, IV). Fakt ten determinuje postępowanie medyczne, będące wypadkową multidyscyplinarnego procesu terapeutycznego. Szereg badań medycznych, oraz programów naukowych jednoznacznie pokazało, że dominującą rolę w leczenia raka jajnika należy wiązać z postępowaniem chirurgicznym. W opinii wielu autorów ultraradykalne zabiegi chirurgiczne wykonywane w jamie brzusznej przez ginekologów onkologów, stanowią istotny statystycznie element wpływający na całkowite przeżycia chorych (OS – Overall Survival), oraz czas wolny do wznowy (PFS – Progresion Free Survival). Niniejsza praca prezentuje przypadek 35-letniej chorej operowanej z powodu zaawansowanego raka jajnika (pT3cN1M1), u której wdrożono ultraradykalne postępowanie operacyjne

What does the volume of stomach resected during Laparoscopic Sleeve Gastrectomy depend on and what impact does it have on postoperative results?

Introduction: Obesity is a chronic, multifactorial disease and its extent is equal to pandemics. Sleeve gastrectomy is one of the methods of obesity treatment. Constantly, research is conducted on factors influencing postoperative bariatric-metabolic results. In this study, a correlation between the volume of stomach resected during LSG with preoperative anthropometric measurements and its influence on postoperative results was analysed. Material and methods: The study included 196 patients who qualified and were subjected to laparoscopic sleeve gastrectomy in the study Centre. Surgery was conducted by the same surgical team according to standard procedure. The volume of the stomach resected was analysed, filling it with CO2 under the pressure of 15 mm Hg. The influence of the volume of stomach resected on bariatric efficiency as well as parameters of lipid and carbohydrate profile results in a 1-year follow-up was analysed. Results: The statistically significant connection between the volume of the stomach resected with preoperative body mass, height and body surface was proved. A correlation between BMI and stomach volume was not found. The volume of stomach resected did not influence body mass loss in a 1-year follow-up. The influence of the volume of the stomach resected on the percentage of glycated haemoglobin and HDL was proved. A significant decrease in body mass and BMI in a 1-year follow-up, as well as an improvement in lipid and carbohydrate balance, was observed. Conclusions: LSG is an efficient method of obesity treatment and for the improvement of biochemical parameters. The volume of stomach resected correlates with preoperative measurements of body mass, height and body surface, but not BMI. There is a lack of correlation between the volume of stomach resected with postoperative body mass loss results

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Zdarzenie-technika-sztuka. Myślenie sztuki filmowej. Obserwacje

Sztuka filmowa kryje w sobie świat realny i rzeczywistość nieznaną, nieuchwytną, wskazując jednocześnie na to, co zakryte, niepoznane, umykające rygorom realności. Jednak granica między tymi dwiema sferami jest płynna i niewyraźna, ponieważ występuje między nimi stały przepływ: stale przedstawiane jest coś nowego i stale coś staje się niejasne, zasłonięte. O czym nie jest ta książka? Z pewnością nie manifestuje jedynie poprawnych poglądów estetycznych, nie odkrywa formuł tworzenia, nie demaskuje manipulacji formalnych, wreszcie nie prezentuje imperatywnych patentów artystycznych. Niniejsza monografia podejmuje jedynie próbę odpowiedzi na pytanie: jaki głębszy sens jest ukryty w działaniach twórcy filmowego

Design of the vibrostabilisation stand for reducing residual stresses in discs used in the construction of multi-plate clutches and brakes

Heavy-duty, oil-cooled brake discs (MMOTs) are often used in heavy-duty brake systems manufactured by companies such as Caterpilar, Clark, Komatsu and Liebherr. These discs are usually made of special steels, and in most cases, the flatness of the working surfaces should not exceed 0.15–0.30 mm. Although the technological processes of friction disc production include several stages of heat treatment and grinding, the required accuracy is not achieved in some cases. In addition, the remaining residual stresses lead to the deformation of the discs during their lifetime. In production practice, three methods are used to reduce residual stresses: thermo-fixing, dynamic stabilisation and vibratory stabilisation consisting in bringing discs to transverse resonance vibrations and maintaining resonance until significant stress reduction. The article proposes a method of stabilising the discs using the resonance phenomenon at the first few frequencies. In this article, Cauchy’s function method and characteristic series method are used to develop solution value problem for clamped circular plates with discrete inclusions as concentrated masses and springs. Calculation methods for quick estimation of the own frequency of discs with additional ring mass enabling the use of low power vibration inductors are presented. The use of a special membrane and a pneumatic cushion in the construction of the stand allows to induce vibrations of higher frequencies