Static and Free Vibration Analyses of Composite Shells Based on Different Shell Theories

Equations of motion with required boundary conditions for doubly curved deep and thick composite shells are shown using two formulations. The first is based upon the formulation that was presented initially by Rath and Das (1973, J. Sound and Vib.) and followed by Reddy (1984, J. Engng. Mech. ASCE). In this formulation, plate stiffness parameters are used for thick shells, which reduced the equations to those applicable for shallow shells. This formulation is widely used but its accuracy has not been completely tested. The second formulation is based upon that of Qatu (1995, Compos. Press. Vessl. Indust.; 1999, Int. J. Solids Struct.). In this formulation, the stiffness parameters are calculated by using exact integration of the stress resultant equations. In addition, Qatu considered the radius of twist in his formulation. In both formulations, first order polynomials for in-plane displacements in the z-direction are utilized allowing for the inclusion of shear deformation and rotary inertia effects (first order shear deformation theory or FSDT). Also, FSDTQ has been modified in this dissertation using the radii of each laminate instead of using the radii of mid-plane in the moment of inertias and stress resultants equations. Exact static and free vibration solutions for isotropic and symmetric and anti-symmetric cross-ply cylindrical shells for different length-to-thickness and length-to-radius ratios are obtained using the above theories. Finally, the equations of motion are put together with the equations of stress resultants to arrive at a system of seventeen first-order differential equations. These equations are solved numerically with the aid of General Differential Quadrature (GDQ) method for isotropic, cross-ply, angle-ply and general lay-up cylindrical shells with different boundary conditions using the above mentioned theories. Results obtained using all three theories (FSDT, FSDTQ and modified FSDTQ) are compared with the results available in literature and those obtained using a three-dimensional (3D) analysis. The latter (3D) is used here mainly to test the accuracy of the shell theories presented here

Static and Free Vibration Analyses of Composite Shells Based on Different Shell Theories

Equations of motion with required boundary conditions for doubly curved deep and thick composite shells are shown using two formulations. The first is based upon the formulation that was presented initially by Rath and Das (1973, J. Sound and Vib.) and followed by Reddy (1984, J. Engng. Mech. ASCE). In this formulation, plate stiffness parameters are used for thick shells, which reduced the equations to those applicable for shallow shells. This formulation is widely used but its accuracy has not been completely tested. The second formulation is based upon that of Qatu (1995, Compos. Press. Vessl. Indust.; 1999, Int. J. Solids Struct.). In this formulation, the stiffness parameters are calculated by using exact integration of the stress resultant equations. In addition, Qatu considered the radius of twist in his formulation. In both formulations, first order polynomials for in-plane displacements in the z-direction are utilized allowing for the inclusion of shear deformation and rotary inertia effects (first order shear deformation theory or FSDT). Also, FSDTQ has been modified in this dissertation using the radii of each laminate instead of using the radii of mid-plane in the moment of inertias and stress resultants equations. Exact static and free vibration solutions for isotropic and symmetric and anti-symmetric cross-ply cylindrical shells for different length-to-thickness and length-to-radius ratios are obtained using the above theories. Finally, the equations of motion are put together with the equations of stress resultants to arrive at a system of seventeen first-order differential equations. These equations are solved numerically with the aid of General Differential Quadrature (GDQ) method for isotropic, cross-ply, angle-ply and general lay-up cylindrical shells with different boundary conditions using the above mentioned theories. Results obtained using all three theories (FSDT, FSDTQ and modified FSDTQ) are compared with the results available in literature and those obtained using a three-dimensional (3D) analysis. The latter (3D) is used here mainly to test the accuracy of the shell theories presented here

Application of TOPSIS method in evaluation and prioritization of social stability in rural areas (Case Study: Zidasht Basin)

In recent years, terms sustainability has been becoming a main study field of too many interdisciplinary sciences. Also, it included suitability theory framework on which every planning designed by taking sustainable development should offer a multidimensional image from the study area. Meanwhile, social sustainability serves as one of the sustainable development components along with qualitative aspects which are evaluated by some concepts like human life and welfare feeling in an ambient. The present study deals with social sustainability level and prioritizes them in three rural centers of the Zidasht basin through six indices (Demographic Index, Literacy Index, Poverty Index, Nutrition Index and Food Security, Index Justice and Equality, Ownership Index) and 18 variables. TOPSIS, as one of the multicriteria decision-making method, was used to prioritize social sustainability. In order to assign weights to corresponding criteria, 20 expertise were used. The result showed that Kalanak has the highest priority with the respective value of 0.7456, followed by Zidasht (0.6003) and Sangbon (0.2303). So that, findings from field studies and observation are in line with these results. Therefore, usage of TOPSIS is suggested in other study areas to prioritize social sustainability.Keywords: prioritization, social sustainable, TOPSIS method, Zidasht basin, rural sustainable developmen

MULTI-OBJECTIVE ROBUST PRODUCTION PLANNING CONSIDERING WORKFORCE EFFICIENCY WITH A METAHEURISTIC SOLUTION APPROACH

Timely delivery of products to customers is one of the main factors of customer satisfaction and a key to the survival of a manufacturing system. Therefore, decreasing wasted time in manufacturing processes significantly affects production delivery time, which can be achieved through the maximization of workforce efficiency. This issue becomes more complicated when the parameters of the production system are under uncertainty. This paper presents a bi-objective scenario-based robust production planning model considering maximizing workforce efficiency and minimizing costs where the backorder, demand, and costs are uncertain. Also, backorder, raw materials purchasing, inventory control, and manufacturing time capacity are considered. A case study in a faucet manufacturing plant is considered to solve the model. Furthermore, the ε-constraint method, the Non-dominated Sorting Genetic Algorithm-II (NSGA-II), the Strength Pareto Evolutionary Algorithm 2 (SPEA2), and the Pareto Envelope-based Selection Algorithm II (PESA-II) are employed to solve the model. Also, the Taguchi method is used to tune the parameters of these algorithms. To compare these algorithms, five indicators are defined. The results show that the SPEA2 is the most time-consuming algorithm and the NSGA-II is the fastest, while their objective function values are nearly the same

Quantitative Modeling of the Equilibration of Two-Phase Solid-Liquid Fe by Atomistic Simulations on Diffusive Time Scales

In this paper, molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM) and a phase-field crystal (PFC) model are utilized to quantitatively investigate the solid-liquid properties of Fe. A set of second nearest-neighbor MEAM parameters for higherature applications are developed for Fe, and the solid-liquid coexisting approach is utilized in MD simulations to accurately calculate the melting point, expansion in melting, latent heat, and solid-liquid interface free energy, and surface anisotropy. The required input properties to determine the PFC model parameters, such as liquid structure factor and fluctuations of atoms in the solid, are also calculated from MD simulations. The PFC parameters are calculated utilizing an iterative procedure from the inputs of MD simulations. The solid-liquid interface free energy and surface anisotropy are calculated using the PFC simulations. Very good agreement is observed between the results of our calculations from MEAM-MD and PFC simulations and the available modeling and experimental results in the literature. As an application of the developed model, the grain boundary free energy of Fe is calculated using the PFC model and the results are compared against experiments

Systematic review of the role of medicinal plants and derived components on reduction of cyclophosphamide-induced toxicity in male genital system

زمینه و هدف: داروی شیمیایی سیکلوفسفامید علی رغم اثرات دارویی چشمگیری که در درمان بیماری های متعدد به ویژه سرطان دارد با عوارض جانبی متعددی همراه می باشد که کاربرد آن را تا حدودی محدود نموده است. این مطالعه مروری قصد دارد اثرات محافظتی گیاهان دارویی و ترکیبات مشتق شده از آن ها را بر کاهش عوارض حاصل از داروی سیکلوفسفامید بر روی دستگاه تناسلی نر مرور و نقش گیاهان را در خصوص کاهش این عوارض جانبی مورد بررسی و تحلیل قرار دهد. روش بررسی: برای انجام این مطالعه مروری واژگان کلیدی سیکلوفسفامید، دستگاه تناسلی نر، سمیت، سرطان، شیمی درمانی، عوارض جانبی در ترکیب با واژگان گیاهان دارویی، داروهای گیاهی و ترکیبات طبیعی از پایگاه های اطلاعاتی ISI، پابمد، اسکاپوس و گوگل اسکالر جستجو شدند. بر اساس معیارهای انتخاب تعداد 20 مقاله که در محدوده سال 2000 تا 2015 منتشر شده بودند انتخاب و وارد مطالعه شدند. یافته ها: از میان 20 مقاله، 13 مقاله مربوط به عصاره­ های گیاهی، 3 مقاله مربوط به ترکیبات فعال گیاهی، 2 مقاله مربوط به اسانس های روغنی و 2 مقاله نیز مربوط به دارو های گیاهی بودند که مشخصات پایه ای آن ها، تاثیر محافظتی این گیاهان و همچنین ترکیبات موثر آن­ها بر روی سمیت دستگاه تولید مثلی جنس نر ناشی از تجویز سیکلوفسفامید مورد بحث قرار گرفت. نتیجه گیری: نتایج این مطالعه نشان داد، گیاهانی که دارای ترکیبات آنتی اکسیدانی نظیر فلاونوئیدها هستند قادرند سمیت ناشی از تجویز سیکلوفسفامید را که سبب بروز استرس اکسیداتیو و افزایش رادیکال­های آزاد می­گردند، در بافت بیضه کاهش دهند؛ لذا پیشنهاد می گردد گیاهانی که اثرات آنتی اکسیدانی چشمگیری دارند در کنار داروی سیکلوفسفامید تجویز و اثرات محافظتی آن ها نسبت به گیاهان و ترکیبات مشتق شده از آن ها که اثرات محافظتی آنها بررسی شده است مقایسه گردد

Kelussia odoratissima Mozzaf - A promising medicinal herb to prevent pulmonary hypertension in broiler chickens reared at high altitude

Ethnopharmacological relevance: Kelussia odoratissima Mozzaf, formerly Apium odoratissima, is a plant locally called ``Karafs'', found in central Zagros region of Iran. Leaves and stems of the plant are traditionally used in the treatment of hypertension and inflammation. Lowering blood pressure effects of Kelussia odoratissima Mozzaf (wild celery) was evaluated in preventing pulmonary hypertension syndrome (PHS) in broiler chickens reared at high altitude (2100 m). Materials and methods: A total number of 208 day-old male broilers (Ross 308) were randomly assigned to four treatments including different levels of Kelussia odoratissima Mozzaf (0%, 0.25%, 0.5%, and 0.75%) in a 42-day trial. Results: Body weight gain and feed:gain responses significantly (P < 0.05) improved when Kelussia odoratissima Mozzaf was included in broiler diets at 0.75% in the growing stage and throughout the trial. Over-expression of inducible nitric oxide (NO) synthase in the heart was observed in chickens fed Kelussia odoratissima Mozzaf. Birds received Kelussia odoratissima Mozzaf at 0.5% and 0.75% had significantly (P <0.05) higher circulatory concentrations of NO though significantly (P < 0.05) lower serum malondialdehyde concentration, hematocrit and heterophil to lymphocyte ratio when compared to the birds fed the control diet. Feeding Kelussia odoratissima Mozzaf at 0.5% and 0.75% prevented from right ventricular hypertrophy and led to a significant decline in mortality from PHS. Conclusion: It can be concluded that Kelussia odoratissima Mozzaf is a promising medicinal herb to prevent PHS in broiler chickens by improving blood pressure and antioxidant responses. (C) 2014 Elsevier Ireland Ltd. All rights reserved

The Effect of Laser Shock Peening (LSP) on the Surface Roughness and Fatigue Behavior of Additively Manufactured Ti-6Al-4V Alloy

Laser shock peening (LSP) uses plasma shock waves to induce compressive residual stress at the surface of a component which has the potential to improve its fatigue properties. For AM parts, the existence of internal defects, surface roughness, and tensile residual stresses leads to noticeably lower fatigue strength compared to materials produced through conventional processes. Furthermore, there is a tendency for greater scatter in the fatigue behavior of these parts when compared to traditionally manufactured components. In this study, the effect of LSP on the roughness and fatigue behavior of Ti-6Al-4V alloy constructed through Laser Powder Bed Fusion (L-PBF) technique was investigated. Two types of samples were designed and tested: as-built surface air foil samples for four-point bending tests and machined surface straight gage samples for uniaxial fatigue testing. Two sets of process parameters, optimized and non-optimized, were also used for the fabrication of each sample type. It was found that LSP had negative effects on the smooth (i.e., machined) surface samples, whereas for as-built surfaces the roughness was enhanced by decreasing the sharpness of the deep valleys and partially remelting the loosely bonded particles on the peaks. It was found that the scatter of the fatigue data decreased for optimized machined samples, while no clear improvement was observed in their lives. However, all non-optimized samples showed improvements in fatigue lives after the LSP process

In vitro lethal effects of various extracts of Nigella sativa seed on hydatid cyst protoscoleces

Objective(s): There are several scolicidal agents for inactivation of hydatid cyst protoscolices during surgery, but most of them are associated with adverse side effects such as sclerosing cholangitis and liver necrosis. The present study was aimed to evaluate scolicidal effects of various extracts of Nigella sativa seeds against protoscoleces of hydatid cyst in an in vitro model. Materials and Methods: Protoscoleces were aseptically aspirated from naturally infected livers of sheep and goats. Various concentrations of the different extracts of N. sativa (5 to 50 mg/ml) were used for 5 to 60 min. Viability of protoscoleces was confirmed by 0.1% eosin staining. Results: The findings exhibited that methanolic extract at the concentration of 50 mg/ml after 10 min of incubation, and aqueous extract at the concentration of 50 mg/ml after 30 min of incubation can kill 100% of protoscoleces. In addition, all of experiments revealed dose-dependent and also time-dependent scolicidal effect of various extracts of N. sativa on the protoscoleces of hydatid cyst. Conclusion: The results of the present study demonstrated that N. sativa may be a natural source for the production of new scolicidal agent for use in hydatid cyst surgery. However, further studies will be required to evaluate scolicidal effects of N. sativa in the in vivo model

Biological properties of Pegylated PLA (PLA-PEG-PLA) and its capability for intracellular delivery of poor soluble peptide drug, gramicidin

Poly lactic acid-co-poly ethylene glycol-co-Poly lactic acid (PLA-PEG-PLA) co-polymer was synthesized and after determination of its biological properties was used for intracellular delivery of poor soluble peptide drug, gramicidin. Toxicity of this polymer on LNCaP cell line was determined by MTT assay. Treatment of cells with fluorescein isothiocyanate (FITC) loaded nanoparticles and fluorescence microscopy indicates ability of this carrier for intracellular delivery. PLA-PEG-PLA nanoparticles containing poor soluble peptide drug, gramicidin, was prepared by solvent evaporation method. In order to confirm loading of gramicidin on PLA-PEG-PLA nanoparticles, FT-IR, spectrofluoremeteric, circular dichroism (CD), and scanning electron microscopy (SEM) studies were carried out. Our studies revealed treatment of prostate cancer cell line, LNCaP, with gramicidin loaded nanoparticles was more effective than gramicidin alone in killing cancer cells