Multi-Step Homogenization of Thermoelastic Multi-Scale Tubes with Wavy Layers

In this paper we present a multi-step homogenization scheme of a tube made of numerous wavy cylindrical layers exhibiting periodicity with respect to both the radial and the angular direction. The proposed homogenization is a combination of successive semi-analytical, cell-problem-based, homogenization steps and a possible, micromechanics-based, homogenization in the interior of every layer. Every step of cell-problem based homogenization gives analytical expressions for the homogenized stiffness, thermal expansion and thermal conductivity

Multiscale homogenization of multilayered structures

In this paper, the analytical solution of the multiple - step homogenization problem for multi - rank composites with generalized periodicity made of elastic materials is presented. The proposed homogenization scheme is combined with computational homogenization for solving more complex microstructures. Two numerical examples arepresented, concerning a “chevron” composite and a wavy fiber reinforced composite.European Union (European Social Fund ESF) and Greek national funds through the Operational Program ”Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF) - Research Funding Program: Thales

Multiscale homogenization of multilayered structures

In this paper, the analytical solution of the multiple - step homogenization problem for multi - rank composites with generalized periodicity made of elastic materials is presented. The proposed homogenization scheme is combined with computational homogenization for solving more complex microstructures. Two numerical examples arepresented, concerning a “chevron” composite and a wavy fiber reinforced composite.European Union (European Social Fund ESF) and Greek national funds through the Operational Program ”Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF) - Research Funding Program: Thales

Effective behavior of thermo-elastic tubes with wavy layers

In the present article, the homogenization of a composite star-shaped tube with numerous thin, periodic, elastic wavy layers, is presented. The composite exhibits a multiscale periodicity allowing for a multistep asymptotic homogenization scheme starting from the finest scale. The scheme gives the complete effective thermoelastic behavior of the composite. By a numerical example of a two-phase composite with sinusoidal wavy walls, whose effective behavior is an orthotropic material, the above method is illustrated

Multi-Step Homogenization of Thermoelastic Multi-Scale Tubes with Wavy Layers

In this paper we present a multi-step homogenization scheme of a tube made of numerous wavy cylindrical layers exhibiting periodicity with respect to both the radial and the angular direction. The proposed homogenization is a combination of successive semi-analytical, cell-problem-based, homogenization steps and a possible, micromechanics-based, homogenization in the interior of every layer. Every step of cell-problem based homogenization gives analytical expressions for the homogenized stiffness, thermal expansion and thermal conductivity

Conservative management for an esophageal perforation in a patient presented with delayed diagnosis: a case report review of the literature

Esophageal perforation is a serious condition with a high mortality rate. Successful therapy depends on the size of the rupture; the time elapsed between rupture and diagnosis, and the underlying health of the patient. Common causes of esophageal perforation include medical instrumentation, foreign-body ingestion, and trauma. A case of esophageal perforation due to fish bone ingestion in a 67-year-old male is described here, with a review of the pertinent literature. The patient presented with chest pain, fever and right-sided pleural effusion. Initial evaluation was nondiagnostic. The water-soluble contrast swallow test showed no evidence of leakage. Computed tomography scan demonstrated a pneumomediastinum, and right-sided hydropneumothorax. The patient was successfully treated using conservative measures

Adrenal metastasis as first presentation of hepatocellular carcinoma

BACKGROUND: Metastases from hepatocellular carcinoma (HCC) can be found in the lung and adrenal gland. We report case of a patient who presented with adrenal metastasis as the first clinical manifestation of HCC. CASE PRESENTATION: A patient was referred for surgical treatment for a tumor in retro-peritoneal space. The computerized tomography (CT) scan revealed a mass originating from the left adrenal gland. The patient underwent left adrenalectomy and the exploration of abdominal cavity did not reveal any other palpable lesions. Histologically, the resected lesion was a poorly differentiated metastatic tumor from HCC. Seven months later patient was readmitted complaining of cachexia, icterus, and significant weight loss. CT scan revealed hyperdense lesions of the liver CONCLUSION: HCC may have atypical presentations like in present case. Fine needle aspiration/tru-cut(® )biopsy might be useful in the investigation of an accidentally discovered adrenal mass regardless of the size and can lead to the detection of a primary tumor

Our local experience with the surgical treatment of ampullary cancer

BACKGROUND: The aim of this study is to report the outcome after surgical treatment of 32 patients with ampullary cancers from 1990 to 1999. METHODS: Twenty-one of them underwent pancreaticoduodenectomy and 9 local excision of the ampullary lesion. The remaining 2 patients underwent palliative surgery. RESULTS: When the final histological diagnosis was compared with the preoperative histological finding on biopsy, accurate diagnosis was preoperatively established in 24 patients. The hospital morbidity was 18.8% as 9 complications occurred in 6 patients. Following local excision of the ampullary cancer, the survival rate at 3 and 5 years was 77.7% and 33.3% respectively. Among the patients that underwent Whipple's procedure, the 3-year survival rate was 76.2% and the 5-year survival rate 62%. CONCLUSION: In this series, local resection was a safe option in patients with significant co-morbidity or small ampullary tumors less than 2 cm in size, and was associated with satisfactory long-term survival rates

Effective properties of multiphase composites made of elastic materials with hierarchical structure

In this paper, the analytical solution of the multi - step homogenization problem for multi - rank composites with generalized periodicity made of elastic materials is presented. The proposed homogenization scheme may be combined with computational homogenization for solving more complex microstructures. Three numerical examples are presented, concerning locally periodic stratified materials, matrices with wavy layers and wavy fiber reinforced composites