• Energy Research

This article assesses the impact of real energy prices on the consumption of different energy sources in Tunisia. We estimate the short-run and long-run energy demand elasticities over the period 1980-2004, where energy demand is specified by a simple partial adjustment model. Our results show that energy demand in Tunisia is generally sensitive to the income level and real prices of energy products. Moreover, the price elasticity and income elasticity differ across energy sources. These findings imply that energy price increases will not only affect energy demand, but also give rise to substitution effects between different forms of energy.

An effort has been made for obtaining higher-order elastic constants for MgO starting from basic parameters, viz. nearest-neighbor distance and hardness parameter using Coulomb and Born-Mayer potentials. These are calculated in a wide temperature range (100–1000 K) and compared with available theoretical and experimental results.

This thesis presents two studies on elastic plates. In the first study, we discuss the choice of elastic energies for thin plates and shells, an unsettled issue with consequences for much recent modeling of soft matter. Through consideration of simple deformations of a thin body in the plane, we demonstrate that four bulk isotropic quadratic elastic theories have fundamentally different predictions with regard to bending behavior. At finite thickness, these qualitative effects persist near the limit of mid-surface isometry, and not all theories predict an isometric ground state. We discuss how certain kinematic measures that arose in early studies of rod mechanics lead to coherent definitions of stretching and bending, and promote the adoption of these quantities in the development of a covariant theory based on stretches rather than metrics. In the second work, the effects of in-plane swelling gradients on thin, anisotropic plates are investigated. We study systems with a separation of scales between bending energy terms. Warped equilibrium shapes are described by two parameters controlling the spatial "rolling up'' and twisting of the surface. Shapes within this two-parameter space are explored, and it is shown that shapes will either be axisymmetric or twisted depending on swelling function parameters and material anisotropy. In some axisymmetric shapes, pitchfork bifurcations to twisted solutions are observed by varying these parameters. We also show that a familiar soft mode of the catenoid to helicoid transformation of an isotropic material no longer exists with material anisotropy. Master of Science This thesis presents two studies on the subject of thin, elastic bodies, otherwise known as plates. Plate theory has important applications in many areas of life, ranging from the design and construction of civil structures to the mechanics of wrinkling sheets. In the first work, we discuss how different elastic plate theories have qualitatively different predictions on how a plate will behave when bent. We discuss the different physical implications of each model, and relate our findings to previous studies. Additionally, we promote the use of certain technical measures in the study of plates corresponding to the most coherent definitions of bending and stretching. In the second work, we study the effects of in-plane swelling gradients on elastic plates whose material stiffnesses vary with direction. Inspired by wood panels that warp when exposed to moisture, we model elastic plates exposed to various swelling patterns and determine the resulting warped shapes. We find that some shapes are axisymmetric, while others prefer to twist when exposed to moisture-induced swelling. By varying certain parameters of the swelling functions, or by increasing the material fiber stiffness, we also find a qualitative change in shape from an axisymmetric to a twisted surface.

Bu çalışmada, boyları ve kesit boyutları farklı olan iki çelik ve iki alüminyum kutu profil numuneler kullanıldı. Kullanılan numunelerin spektral girdi enerjileri analitik çalışmada on farklı periyotta San Salvador, Loma Prieta ve Erzincan depremi altında elastik bölgede hesaplandı. Numuneler arasındaki giren enerji oranının ölçek faktörü yedi farklı iki durumlarla boya, kesit boyutlarına ve malzeme türüne bağlı olarak hesaplandı. Her ikili durum için, spektral giren enerji ölçek faktörü malzeme elastik modülü oranı, uzunluk oranı ve periyot oranlarına bağlı olarak hesaplandı. Yedi farklı ikili durumlarda elde edilen yapıya gelen enerji değerleri kendi içlerinde oranlanmıştır ve giren enerji için ölçek faktörü belirlendi. Çelik ve alüminyum numunelerin modellemeleri SAP2000 programıyla yapıldı ve enerji değerleri bu programla hesaplanarak bulunuldu. Spektral enerji değerleri deprem özelliklerine göre Ahmet Anıl Dindar (2015) giren enerji spektrum eğrisi ile karşılaştırıldı.. Deneysel çalışmalar dört numune için üç farklı periyot ve tanımlanan üç farklı deprem altında sarsma masası kullanılarak yapıldı. Her numunenin spektral giren enerji değeri deney sonucundan hesaplandı. Numerik hesaplama sonucu spektral giren enerji değeri deneysel hesaplama sonucu giren enerjiyle karşılaştırıldı ve uyumluluk gösterdiler. Ayrıca, analitik çalışmalar ve deneysel çalışmalar giren enerji için ölçek faktörünün aynı yer hareketi altında numuneler arasındaki kütle ölçek faktörüne eşit olduğunu göstermiştir. In this study, two steel hollow section specimens and two aluminum hollow section specimens with different length and cross-sectional dimensions were used. In the analytical part, spectral input energy of these specimens was calculated with ten different periods under San Salvador, Loma Prieta and Erzincan ground motion records in elastic range. The scale factor for spectral input energy between specimens were calculated with seven different cases in terms of length, cross-sectional dimension and material properties. For each defined binary state, input energy scale factor was determined based on material elasticity modulus ratio, length ratio and period ratio between the specimens. In those seven different binary states, spectral input energy values were proportioned and scale factor for input energy was determined. Steel and aluminum specimens' numerical models were constructed using SAP2000 Structural Analysis software and their corresponding energy values for each period under defined earthquake ground motion were calculated. Spectral energy values were compared with existing mass-normalized input energy spectra (A.A. Dindar, 2015) based on earthquake properties. Experimental studies were carried out with four specimens, three different periods and under three different earthquake ground motion records by using shake table. Spectral input energy for each specimen was calculated from the experimental data. Numerical modelling results for spectral input energy values were compared with experimental results and they all showed good agreement. Also, experimental and analytical studies showed that scale factor for spectral input energy is equal to mass scale factor between the specimens for a given ground motion data. 152