# Multidisciplinary Design Project Engineering Dictionary Version 0.0.2

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• Glossary Physics (I-Introduction)
1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay.
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• 10-1 CHAPTER 10 DEFORMATION 10.1 Stress-Strain Diagrams And
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• Non-Equilibrium Carrier Concentrations
ECE 531 Semiconductor Devices Lecture Notes { 06 Dr. Andre Zeumault Outline 1 Overview 1 2 Revisiting Equilibrium Considerations1 2.1 What is Meant by Thermal Equilibrium?........................1 2.2 Non-Equilibrium Carrier Concentrations.........................3 3 Recombination and Generation3 3.1 Generation.........................................3 4 Continuity Equations5 4.1 Minority Carrier Diﬀusion Equations...........................5 5 Quasi-Fermi Levels8 1 Overview So far, we have only discussed charge carrier concentrations under equilibrium conditions. Since no current can ﬂow in thermal equilibrium, this particular case isn't much interest to us in trying to create electronic devices. Therefore, in this lecture, we discuss the situations and governing equations in which a charge carrier responds under non-equilibrium conditions. Topics to be covered include: • Recombination and Generation: An increase (generation) or decrease (recombination) in charge carrier concentrations away from or towards equilibrium. (e.g. due to absorption of light) • Current Continuity: Charge conservation, applied in the context of drift/diﬀusion. • Minority Carrier Diﬀusion Equations: Minority carrier diﬀusion in the presence of a large majority carrier concentration. • Quasi-Fermi Levels: Treating carrier densities under non-equilibrium conditions. 2 Revisiting Equilibrium Considerations 2.1 What is Meant by Thermal Equilibrium? When we discussed equilibrium charge carrier concentrations, it was argued that the production of charge carriers was thermally activated. This was shown to be true regardless of whether or not the semiconductor was intrinsic or extrinsic. When a semiconductor is intrinsic, the thermal energy necessary for charge carrier production is the bandgap energy EG, which corresponds to the energy needed to break a Silicon-Silicon covalent bond.
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• Center of Mass and Centroids
Center of Mass and Centroids Center of Mass A body of mass m in equilibrium under the action of tension in the cord, and resultant W of the gravitational forces acting on all particles of the body. -The resultant is collinear with the cord Suspend the body at different points -Dotted lines show lines of action of the resultant force in each case. -These lines of action will be concurrent at a single point G As long as dimensions of the body are smaller compared with those of the earth. - we assume uniform and parallel force field due to the gravitational attraction of the earth. The unique Point G is called the Center of Gravity of the body (CG) ME101 - Division III Kaustubh Dasgupta 1 Center of Mass and Centroids Determination of CG - Apply Principle of Moments Moment of resultant gravitational force W about any axis equals sum of the moments about the same axis of the gravitational forces dW acting on all particles treated as infinitesimal elements. Weight of the body W = ∫dW Moment of weight of an element (dW) @ x-axis = ydW Sum of moments for all elements of body = ∫ydW From Principle of Moments: ∫ydW = ӯ W Moment of dW @ z axis??? xdW ydW zdW x y z = 0 or, 0 W W W Numerator of these expressions represents the sum of the moments; Product of W and corresponding coordinate of G represents the moment of the sum Moment Principle. ME101 - Division III Kaustubh Dasgupta 2 Center of Mass and Centroids xdW ydW zdW x y z Determination of CG W W W Substituting W = mg and dW = gdm xdm ydm zdm x y z m m m In vector notations:
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• Dynamics of Urban Centre and Concepts of Symmetry: Centroid and Weighted Mean
Jong-Jin Park Research École Polytechnique Fédérale de Dynamics of Urban Centre and Lausanne (EPFL) Laboratoire de projet urbain, Concepts of Symmetry: territorial et architectural (UTA) Centroid and Weighted Mean BP 4137, Station 16 CH-1015 Lausanne Presented at Nexus 2010: Relationships Between Architecture SWITZERLAND and Mathematics, Porto, 13-15 June 2010. [email protected] Abstract. The city is a kind of complex system being capable Keywords: evolving structure, of auto-organization of its programs and adapts a principle of urban system, programmatic economy in its form generating process. A new concept of moving centre, centroid, dynamic centre in urban system, called “the programmatic weighted mean, symmetric moving centre”, can be used to represent the successive optimization, successive appearances of various programs based on collective facilities equilibrium and their potential values. The absolute central point is substituted by a magnetic field composed of several interactions among the collective facilities and also by the changing value of programs through time. The center moves continually into this interactive field. Consequently, we introduce mathematical methods of analysis such as “the centroid” and “the weighted mean” to calculate and visualize the dynamics of the urban centre. These methods heavily depend upon symmetry. We will describe and establish the moving centre from a point of view of symmetric optimization that answers the question of the evolution and successive equilibrium of the city. In order to explain and represent dynamic transformations in urban area, we tested this programmatic moving center in unstable and new urban environments such as agglomeration areas around Lausanne in Switzerland.
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• Wastewater Technology Fact Sheet: Ammonia Stripping
United States Office of Water EPA 832-F-00-019 Environmental Protection Washington, D.C. September 2000 Agency Wastewater Technology Fact Sheet Ammonia Stripping DESCRIPTION Ammonia stripping is a simple desorption process used to lower the ammonia content of a wastewater stream. Some wastewaters contain large amounts of ammonia and/or nitrogen-containing compounds that may readily form ammonia. It is often easier and less expensive to remove nitrogen from wastewater in the form of ammonia than to convert it to nitrate-nitrogen before removing it (Culp et al., 1978). Ammonia (a weak base) reacts with water (a weak acid) to form ammonium hydroxide. In ammonia stripping, lime or caustic is added to the wastewater until the pH reaches 10.8 to 11.5 standard units which converts ammonium hydroxide ions to ammonia gas according to the following reaction(s): + - NH4 + OH 6 H2O + NH38 Source: Culp, et. al, 1978. Figure 1 illustrates two variations of ammonia FIGURE 1 TWO TYPES OF STRIPPING stripping towers, cross-flow and countercurrent. In TOWERS a cross-flow tower, the solvent gas (air) enters along the entire depth of fill and flows through the packing, as the alkaline wastewater flows it may be more economical to use alternate downward. A countercurrent tower draws air ammonia removal techniques, such as steam through openings at the bottom, as wastewater is stripping or biological methods. Air stripping may pumped to the top of a packed tower. Free also be used to remove many hydrophobic organic ammonia (NH3) is stripped from falling water molecules (Nutrient Control, 1983). droplets into the air stream, then discharged to the atmosphere.
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• Synthesis and Characterisation of Carbide Derived Carbons
Synthesis and Characterisation of Carbide Derived Carbons Sigita Urbonaite Department of Physical, Inorganic and Structural Chemistry Stockholm University 2008 Doctoral Thesis 2008 Department of Physical, Inorganic and Structural Chemistry Stockholm University Cover: Some artefacts found during TEM investigation of CDCs. Faculty opponent: Prof. Rik Brydson Department of Nanoscale Materials Characterisation Institute for Materials Research University of Leeds, UK Evaluation committee: Prof. Bertil Sundqvist, Nanofysik och material, UmU Prof. Margareta Sundberg, Strukturkemi, SU Prof. Kristina Edström, Strukturkemi, UU Docent Lioubov Belova, Teknisk materialfysik, KTH © Sigita Urbonaite, Stockholm 2008 ISBN 978-91-7155-589-2 pp. 1-82. Printed in Sweden by US-AB, Stockholm 2008 Distributor: FOOS/Structurkemi ii ABSTRACT Carbide derived carbons (CDCs) have been synthesised through chlorina- tion of VC, TiC, WC, TaC, NbC, HfC and ZrC at different temperatures. The aim of the investigation was to systematically study changes of struc- tural and adsorption properties depending on the synthesis conditions. CDCs were characterised using nitrogen and carbon dioxide adsorption, Raman spectroscopy, scanning electron microscopy, transmission electron micros- copy, and electron energy loss spectroscopy. The studies revealed the CDCs structures to range from amorphous to ordered, from microporous to mesoporous. It was found that structural ordering and porosity can be modi- fied by: i) synthesis temperature, ii) precursor, iii) density and volume of precursor, iv) catalysts, v) incorporation of nitrogen in to carbide structure, and CDCs can be tuned up to the demanded quality. They also exhibited a high potential for methane storage. iii iv LIST OF PUBLICATIONS Paper I. Porosity development along the synthesis of carbons from metal carbides S.
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• Hydrogen Bond Assisted Adhesion in Portland Cement-Based Materials