Comparison of Stability Criteria for Concrete Dams in Different Approximate Methods Based on Finite Element Analysis

AbstractDifferent regulations for the design of concrete dams suggest various criteria for stability control of dams. Some of these criteria, which are conservative, lead to the over-design of dam sections. By using the finite element method, which is considered more accurate than many, this research is intended to determine the accuracy of approximate methods and compare them with each other. Since, according to the regulations, the length of an established crack within the interface between the dam and its foundation is considered a stability indicator to calculate overturning and sliding, the same index has been used here. To give a practical example, using the approximate methods of the U.S. Army Corps of Engineers, U.S. Bureau of Reclamation, and U.S. Federal Energy Regulatory Commission regulations for gravity dams, the stability control and safety factors are calculated in all three. Then, the same example is analyzed on the basis of finite element analytical software such as ANSYS as well as the uplift pressure distribution of regulations, and the safety factors are determined and compared with those calculated by other methods. It is important to note that none of the above regulations refers to the elastic properties of foundation materials in the calculation of base stress distribution and safety factors. Accordingly, for different kinds of foundation materials, the stresses of the base are calculated in the same way, and the types of materials have no effect on the safety factors related to stability. This poses a serious problem in all the above regulations, but this problem does not exist in the finite element method. This research demonstrates the necessity of the finite element method for analyzing gravity dams, even in their initial design phase

Application of silicon-polymer composite varistors to protect sensitive medical imaging circuits and performing better voltage bias for SiPMs

Nowadays, Silicon photomultipliers (SiPM) become a reasonable choice for Time-of-Flight Positron Emission Tomography (TOF-PET). To achieve the best performance of SiPMs, it is necessary to adjust a suitable voltage bias. In this article, we are using varistors which protect SiPM from voltage fluctuations. The silicon-polymer composite varistors prepared using hot press method have been investigated. Research on (current-voltage) characteristics of samples shows that by increasing silicon content in the mixture, the breakdown voltage decreases from 110 V to 70 V. The results also show that increasing silicon content decreases the potential barrier height from 0.29 eV to 0.26 eV, however, leakage current increases. Increasing silicon content increases nonlinear coefficient from 4.1 to 4.8. Using these techniques gives us ability to produce suitable surge protector for medical imaging modalitie

Value-based Characterization of Cultural Landscapes: The Cases of Villa Thompson and Villa Sparrow, Mont-Royal, Montreal

This thesis is a cultural study of the cultural landscape of Villa Thompson and Villa Sparrow located on Mont Royal, a Natural and Historic District in Montreal, Canada. Mont Royal has in time gained a high level of notoriety and authority for informing the cultural history of Montreal, Quebec and Canada, and this site is read using value-based theory and methodology, a practice first applied to historic buildings and monuments analysis in the early 20th century. In response to the expansion of the notion of heritage and the need for better tools to analyze and understand historic territories, “characterization” as field of inquiry and methodology was put forward in the early 1990s, offering new ideas for understanding cultural landscapes. This study argues that a value-based characterization provides a useful understanding of this territory, and one which contributes to a better understanding of all territories through a more lucid knowledge-based cultural landscapes strategy. Defining a secure knowledge-base thusly paves the way to bring cultural landscapes into meaningful recognition and conservation. Mont Royal, including the Thompson and Sparrow Villas, has been recognized as a National Historic Site by the Government of Canada, a Natural and Historic District, Arrondissment Historique, by the Government of Quebec and as a Heritage Site by the City of Montreal. Furthermore, the cultural landscape of the Thompson and Sparrow Villas is recognized and designated as Historic Site, or Site Historique, by the Government of Quebec. These recognitions are, by and large, based on the symbolic and emblematic values placed on Mont Royal and these buildings, and Montrealers' sentimental attachments to and appropriation of the space, as well as the urgent need for its protection. This study argues that the site of Thompson and Sparrow Villas, as a cultural landscape, is a valid cultural document, and therefore requires understanding through cultural study within the field of inquiry and methodology of characterization. From its role as a crossroads for aboriginal peoples for thousands of years, to its first European occupation by French settlers, to its exploitation as agricultural land, to its appropriation for leisure, and finally to its occupation by English merchants and their luxurious villas, this cultural landscape and Mont Royal as a whole are considered worthy texts for reading, analyzing and understanding the cultural values, world views and history of their successive occupants

Perspectives on the role of non-coding rnas in the regulation of expression and function of the estrogen receptor

Estrogen receptors (ERs) comprise several nuclear and membrane-bound receptors with different tissue-specific functions. ERα and ERβ are two nuclear members of this family, whereas G protein-coupled estrogen receptor (GPER), ER-X, and Gq-coupled membrane estrogen receptor (Gq-mER) are membrane-bound G protein-coupled proteins. ERα participates in the development and function of several body organs such as the reproductive system, brain, heart and musculoskeletal systems. ERβ has a highly tissue-specific expression pattern, particularly in the female reproductive system, and exerts tumor-suppressive roles in some tissues. Recent studies have revealed functional links between both nuclear and membrane-bound ERs and non-coding RNAs. Several oncogenic lncRNAs and miRNAs have been shown to exert their effects through the modulation of the expression of ERs. Moreover, treatment with estradiol has been shown to alter the malignant behavior of cancer cells through functional axes composed of non-coding RNAs and ERs. The interaction between ERs and non-coding RNAs has functional relevance in several human pathologies associated with estrogen regulation, such as cancers, intervertebral disc degeneration, coronary heart disease and diabetes. In the current review, we summarize scientific literature on the role of miRNAs and lncRNAs on ER-associated signaling and related disorders

Exploring the role of non-coding rnas in the pathophysiology of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic immune-related disorder designated by a lack of tolerance to self-antigens and the over-secretion of autoantibodies against several cellular compartments. Although the exact pathophysiology of SLE has not been clarified yet, this disorder has a strong genetic component based on the results of familial aggregation and twin studies. Variation in the expression of non-coding RNAs has been shown to influence both susceptibility to SLE and the clinical course of this disorder. Several long non-coding RNAs (lncRNAs) such as GAS5, MALAT1 and NEAT1 are dysregulated in SLE patients. Moreover, genetic variants within lncRNAs such as SLEAR and linc00513 have been associated with risk of this disorder. The dysregulation of a number of lncRNAs in the peripheral blood of SLE patients has potentiated them as biomarkers for diagnosis, disease activity and therapeutic response. MicroRNAs (miRNAs) have also been shown to affect apoptosis and the function of immune cells. Taken together, there is a compelling rationale for the better understanding of the involvement of these two classes of non-coding RNAs in the pathogenesis of SLE. Clarification of the function of these transcripts has the potential to elucidate the molecular pathophysiology of SLE and provide new opportunities for the development of targeted therapies for this disorder

Optimal distribution coefficients of energy resources in frequency stability of hybrid microgrids connected to the power system

The continuous stability of hybrid microgrids (MGs) has been recently proposed as a critical topic, due to the ever-increasing growth of renewable energy sources (RESs) in low-inertia power systems. However, the stochastic and intermittent nature of RESs poses serious challenges for the stability and frequency regulation of MGs. In this regard, frequency control ancillary services (FCAS) can be introduced to alleviate the transient effects during substantial variations in the operating point and the separation from main power grids. In this paper, an efficient scheme is introduced to create a coordination among distributed energy resources (DERs), including combined heat and power, diesel engine generator, wind turbine generators, and photovoltaic panels. In this scheme, the frequency regulation signal is assigned to DERs based on several distribution coefficients, which are calculated through conducting a multi-objective optimization problem in the MATLAB environment. A meta-heuristic approach, known as the artificial bee colony algorithm, is deployed to determine optimal solutions. To prove the efficiency of the proposed scheme, the design is implemented on a hybrid MG. Various operational conditions which render the system prone to experience frequency fluctuation, including switching operation, load disturbance, and reduction in the total inertia of hybrid microgrids, are studied in PSCAD software. Simulation results demonstrate that this optimal control scheme can yield a more satisfactory performance in the presence of grid-following and grid-forming resources during different operational conditions

First record of Leucopis (Leucopis) spyrothecae (Dip.: Chamaemyiidae) from Iran

طی نمونه‌برداری‌های انجام‌شده از دشمنان طبیعی شته‌ها در اردبیل طی سال‌های 91-1390، لاروهای مگس شکارگر از خانواده Chamaemyiidae در حال تغذیه از شته Pemphigus spyrothecae Passerini روی درخت صنوبر، Populus nigra (L.)، جمع‌آوری و پس‌ از پرورش در شرایطی مشابه شرایط محل جمع‌آوری، حشرات کامل به نام Leucopis (Leucopis) spyrothecae Raspi, 2003 شناسایی شدند. این گونه برای اولین‌بار از ایران گزارش می‌شود

The Impact of Non-coding RNAs in the Epithelial to Mesenchymal Transition

Epithelial to mesenchymal transition (EMT) is a course of action that enables a polarized epithelial cell to undertake numerous biochemical alterations that allow it to adopt features of mesenchymal cells such as high migratory ability, invasive properties, resistance to apoptosis, and importantly higher-order formation of extracellular matrix elements. EMT has important roles in implantation and gastrulation of the embryo, inflammatory reactions and fibrosis, and transformation of cancer cells, their invasiveness and metastatic ability. Regarding the importance of EMT in the invasive progression of cancer, this process has been well studies in in this context. Non-coding RNAs (ncRNAs) have been shown to exert critical function in the regulation of cellular processes that are involved in the EMT. These processes include regulation of some transcription factors namely SNAI1 and SNAI2, ZEB1 and ZEB2, Twist, and E12/E47, modulation of chromatin configuration, alternative splicing, and protein stability and subcellular location of proteins. In the present paper, we describe the influence of ncRNAs including microRNAs and long non-coding RNAs in the EMT process and their application as biomarkers for this process and cancer progression and their potential as therapeutic targets