...35 mm thickness of steel [thermal conductivity = 45 W/(m K)]. Assume the layers to be in very good thermal contact. Figure. Layers in a composite furnace wall. The temperature T0 on the inside of the refractory is 1370oC, while the temperature T3 on the outside of the steel plate is 37.8oC. The heat loss through the furnace wall is expected to be 15800 W/m2. Determine the thickness of refractory and insulation that results in the minimum total thickness of the wall. Given thermal conductivities in W/(m K): Layer k at 37.8oC k at 1093oC Refractory 3.12 6.23 Insulation 1.56 3.12 ________________________________________ Solution. Click here for stepwise solution Click here for stepwise solution Step. Thermal resistance representation for composite furnace wall Step. Thermal resistance representation for composite furnace wall In general, the heat flow is given by Q = T/Rth and the thermal resistance for a rectangular slab is Rth = x/(kA), where T is the temperature driving force (thermal potential difference), x is the slab thickness, k is the thermal conductivity, and A is the cross-sectional area of the slab. The thermal resistances for the three layers are in series as shown in the figure below. Figure. Thermal resistance representation of composite furnace wall. Based on the thermal resistance representation for the composite furnace wall, the heat flux q is (1) In the refractory and insulation, the thermal conductivity k varies with...
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...1. Define heat. Heat- is energy transferred from one body to another by thermal interactions. The transfer of energy can occur in a variety of ways, among them conduction, radiation, and convection. Heat is not a property of a system or body, but instead is always associated with a process of some kind, and is synonymous with heat flow and heat transfer. 2. Differentiate heat from temperature The heat is the energy transferred from one body while the temperature is the amount of hotness or coldness of a body. 3. How heat is related to thermal energy Heat is thermal energy in the process of transfer or conversion across a boundary of one region of matter to another, as a result of a temperature difference. In engineering, the terms "heat" and "heat transfer" are thus used nearly interchangeably (heat transfer is the rate of heat flow in time, or the heat power), since heat is always understood to be in the process of transfer. The energy transferred by heat is called by other terms (such as thermal energy or latent energy) when this energy is no longer in net transfer, and has become static. Thus, heat is not a static property of matter. Matter does not contain heat, but rather thermal energy, and even the thermal energy is subject to transformations into and out of other types of energy, and so can be considered to be "conserved" only when these processes are small. 4. Explain how temperature is measured 6. Explain how heat is transferred by conduction, convection...
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...Why? When we measure the conductance of benzene-1, 4- dithiolate molecule using break-junction technique, how can we judge the point when a single molecule is connecting two gold electrodes? Ans: A break junction is an electronic device which consists of two metal wires separated by a very thin gap, on the order of the inter-atomic spacing (less than a nanometer). This can be done by physically pulling the wires apart or through chemical etching or electromigration. As the wire breaks, the separation between the electrodes can be indirectly controlled by monitoring the electrical resistance of the junction. In this technique a metal wire is bent or pulled, often using a piezoelectric crystal to apply the necessary force. The bending or pulling causes the metal wire to break in a controlled manner since piezoelectric elongation can be controlled to a precision of angstroms or less. As the wire breaks, the separation between the electrodes can be indirectly controlled by monitoring the electrical current through the junction. Procedure: 1) Break junction method: * Fabricate a thin metal wire on top of flexible substrate (e.g.polymide) by optical or e-beam lithography, or glue the wire to substrate by epoxy. * Notch the wire with a sharp object (or e-beam lithography). * Bending the substrate to break the wire at notch point (flexible substrate: not broken). * Relax the bending to bring into two wire parts back to contact. Electromigration: ...
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.... POINT OF VIEW This case is analyzed from the point of view of a third party consultant. II. PROBLEM There is inefficiency in the management of Krispy Kreme Doughnuts, Inc. in terms of its operations, marketing, accounting, and investment planning. III. OBJECTIVES a. To gradually gain back analysts’, investors’ and lenders’ confidence in the company in the succeeding months. b. To increase sales and profitability in terms of its core business, selling of doughnuts. c. To regain and increase stock price therefore increasing shareholder value. d. To correct inaccurate entries in the financial statements of KKD and to present a clean and unbiased reports. e. To extend further reach to consumers strategically to achieve significant growth in the next five years. f. To implement extensive marketing measures for its brand and products and investment strategy for both on and off premise operations. IV. AREAS OF CONSIDERATION • Fortune magazine had dubbed Krispy Kreme Doughnut, Inc. “the hottest brand in America.” With ambitious plans to open 500 doughnut shops over the first half of the decade. • The company generated revenues through four primary sources: on-premise retail sales at company owned stores (27% of revenues), off-premises sales to grocery and convenience stores (40%); manufacturing and distribution of product mix and machinery (29%); and franchise royalties and fees (4%). • Roughly 60% of sales at a Krispy Kreme store were derived...
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...ME3281 Microsystems Design and Applications TERM PAPER DEPARTMENT OF MECHANICAL ENGINEERING MEMS Energy Harvesters LIM HUI HUA ALVINA A0083044M 2014 Table of Contents 1. Introduction: 2 2. Brief History of Electricity Transduction 2 3. Types of Micro Energy Harvesters 3 3.1 Energy Harvesting from Vibration 3 3.1.1 Fabrication Techniques 5 3.1.2 Applications, Challenges and the Future 6 3.2 Energy Harvesting from Thermal Sources 6 3.2.1 Fabrication Techniques 8 3.2.2 Applications, Challenges and the Future. 9 3.3 Energy Harvesting from Electromagnetic Waves 10 3.3.1 Applications, Challenges and the Future 11 3.4 Energy Harvesting from Light Sources 11 3.4.1 Fabrication 12 3.4.2 Applications, Challenges and the Future 13 4. Conclusion 13 References: 14 1. Introduction: One of the goals of engineers and scientists in this already tech-savvy age is to be able to design a device that is capable of powering itself for its lifetime without having to replace or recharge its battery using a power chord. These allow remote devices to be placed in hostile or inaccessible environments without requiring any or little maintenance such as the changing of batteries. This is especially applicable for silicon-based electronics, such as biomedical implants that have low power consumption, where batteries will largely affect its size; operational cost of the device, or perhaps even release harmful chemicals into the body. In addition, wireless sensor...
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...textbooks is 1atmosphere = 101kPa = 760torr There are two pressure regimes of interest to the scientist working with vacuum systems, and gases behave differently in each regime. The first, the viscous flow regime, describes the case where gas flows as a fluid, where the mean free path of the gas molecules is much smaller than the dimensions of the apparatus. The second, the molecular flow regime, describes the high-vacuum case, where the mean free path is much longer than the characteristic dimensions of the apparatus. In this regime, gas molecules interact almost entirely with the walls of the chamber, acting independent of each other. Gas flow in either regime is measured in torr liters per second, which is equivalent to mass per second. The conductance of a tube describes how much gas flows through the tube for a given pressure...
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...MECHANICAL ENGINEERING DETERMINATION OF THERMAL CONDUCTIVITY OF WASTE MATERIAL (PLASTICS) MECHANICAL ENGINEERING LABORATORY 2 ME 11L SUBMITTED BY: Alega, Ulysses Jr. H. Bicaldo, Mark Zedrick L. Engaño, Moises A. Sabida, Ricalyn B. SUBMITTED TO: Engr. Manuel E. Europeo March 10, 2014 INTRODUCTION Heat conduction (or thermal conduction) is the transfer of internal energy by microscopic diffusion and collisions of particles or quasi-particles within a body due to a temperature gradient. The microscopically diffusing and colliding objects include molecules, electrons, atoms, and phonons. They transfer disorganized microscopic kinetic and potential energy, which are jointly known as internal energy. Conduction can only take place within an object or material, or between two objects that are in direct or indirect contact with each other. Conduction takes place in all forms of ponderable, such as solids, liquids, gases and plasmas. Whether by conduction or by thermal radiation, heat spontaneously flows from a hotter to a colder body. In the absence of external drivers, temperature differences decay over time, and the bodies approach thermal equilibrium. In conduction, the heat flow is within and through the body itself. In contrast, in heat transfer by thermal radiation, the transfer is often between bodies, which can be spatially separate. Also possible is transfer of heat by a combination of conduction and thermal radiation. In convection, internal energy...
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...“MILLIPEDE” - STORAGE TECHNOLOGY Sameer Tayal (sameer.tayal@gmail.com) ABSTRACT Through this paper we report a new atomic force microscope (AFM)-based data storage concept called the “Millipede” that has a potentially ultrahigh density, terabit capacity, small form factor, and high data rate. Its potential for ultrahigh storage density can be used as a technique to store and read back data in very thin polymer films. With this new technique, 3040-nm-sized bit indentations of similar pitch size have been made by a single cantilever/tip in a thin (50-nm) polymethylmethacrylate (PMMA) layer, resulting in a data storage density of 400-500 Gb/in.2 High data rates are achieved by parallel operation of large two-dimensional (2D) AFM arrays that have been batch-fabricated by silicon surface-micromachining techniques. The very large scale integration (VLSI) of micro devices (cantilevers/tips) on a single chip leads to the largest and densest 2D array of 32 x 32 (1024) AFM cantilevers with integrated write/read storage functionality ever built. Timemultiplexed electronics control the write/read storage cycles for parallel operation of the Millipede array chip. Initial areal densities of 100-200 Gb/in.2 have been achieved with the 32 × 32 array chip, which has potential for further improvements. In addition to data storage in polymers or other media, and not excluding magnetics, we envision areas in nanoscale science and technology such as lithography, high-speed/large-scale imaging...
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...highlight of the past year is the unfolding and refolding of the muscle protein titin in the atomic force microscope. A related highlight in the intersection between experiment and theory is a recent review of the effects of molecular forces on biochemical kinetics. Other advances in scanning probe microscopy include entropic brushes, molecular sandwiches and applications of atomic force microscopy to gene therapy. Address Department of Physics, University of California, Santa Barbara, CA 93106, USA Current Opinion in Chemical Biology 1998, 2:579–584 http://biomednet.com/elecref/1367593100200579 © Current Biology Ltd ISSN 1367-5931 Abbreviations AFM atomic force microscopy/microscope SFM scanning force microscopy/microscope SICM scanning ion conductance microscopy/microscope SPM scanning probe microscopy/microscope STM scanning tunneling microscopy/microscope A new journal, Probe Microscopy, was launched in 1997 as a forum specifically devoted to the science and technology of SPM. AFM and SFM have been also newsworthy items in Science and Nature in the past year [14••,15•–17•,18••,19]. An introduction to AFM is covered well in a recent issue of Current Opinion in Chemical Biology, which describes and illustrates the design and mode of operation of AFM [4••]. The AFM images sample surfaces by raster-scanning a sharp tip back and forth over the surface. The tip is on a cantilever that responds to height changes on the sample surface in a way that generates a topographical map of the...
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...for survival during the winter, while the temperature drops to freezing point and the pH rises to above 10. Secondarily, the water that the Black Lake is composed of is salt water with 1.5 Osmol/L salinity with no currents. Finally, the lake itself is pitch black and inhabited by other species that will feed upon the Grindylow. These features of the Black Lake would need to be addressed when proposing a viable mechanism for Grindylow's survival. The Grindylows live in a marine environment that have large temperature fluctuations which would most likely make them Ectotherms. The properties of water encourages the living organisms that inhabit it to be thermo-conformers due to heat loss into the surrounding. All organism seeks to maintain thermal balance where the net heat gain equates the net heat loss. Water's high specific heat capacity makes it an infinite heat sink and any metabolically produced heat from a specimen is quickly transferred into the environment, moreover, the transfer of heat into the water is of a higher rate than oxygen thus heat equilibrates before oxygen transfer is complete. The surface area of respiration for the Grindylow is their gills, where as their surface area for heat transfer is their whole body thus by Fick's and Fourier's Law the heat will be lost more quickly than oxygen being diffused through the respiratory membrane. The high viscosity of the liquid also encourages unidirectional flow to maximize oxygenation of blood. However, by being a thermo-conformer...
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...1 Instrumentation Diagram of SWCS C. Equipment and Instrumentation of SWCS 1) Conductivity Measurement: A conductivity meter measures the amount of electrical current are conductance in a solution .Conductivity is useful in determining the overall health of the neutral water body. Within the primary water system the conductivity of the primary water is supervised on Downstream of the ion exchange and Upstream of generator inlet. The meter is equipped with a probe, usually handheld, for field Measurements, after the probe is placed in the liquid to be measured, the meter applies voltage between two electrodes inside the probe. The measuring point downstream of the ion exchanger serves for checking the ion exchange for proper performance. The measuring point on the primary water inlet to the generator permits the conductivity of the entire cooling circuit. Both measuring devices are equipped for indication and alarm...
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...shown. 5. Neat work will earn good marks. 6. Graphs should be made by hands. MS excel graphs will not be accepted. LAB MARKS DISTRIBUTION LAB REPORT/ ATTENDENCE | 50% | LAB PERFORMANCE | 10% | MID TERM ASSESMENT/QUIZES | 10% | FINAL LAB ASSESMENT | 30 % | TOTAL | 100% | TABLE OF CONTENTS S.NO | DATE | OBJECTIVE | PAGE NO | SIGNATURE | 1. | | To show that the intensity of radiation on a surface is inversely proportional to the square of the distance of the surface from the source of radiation | | | 2. | | To show the intensity of radiation various as fourth power of source. | | | 3. | | Determination of barrier temperature gradient between two different metals in end to end pressure contact. | | | 4. | | To perform energy balance on air flowing throw a duct heated by cylindrical rod | | | 5. | | To perform energy balance on air flowing throw a duct heated by cylindrical rod using DAQ | | | 6. | | Determination of a mean surface heat transfer coefficient for tubes in 1 to 16 rows of cross flow heat exchange | | | 7. | | Measurement of heat flux and surface heat transfer coefficient during filmwise and dropwise condensation. | | | 8. | | Calculation of heat exchanger effectiveness under various conditions such as counter, parallel flow rates of hot and cold fluids. | | |...
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...semiconductor industry over the last few decades. In order to mitigate short channel effects, the gate-oxide thickness and source/drain junction depth have been scaled along with the gate length. Recently, however, gate-oxide thickness scaling has slowed, as evidenced by the fact that an equivalent oxide thickness (EOT) of ~1 nm has been used for the past 2-3 generations of CMOS technology. Although significant progress has been made in the development of high-permittivity (high-κ) gate-dielectric materials and metal gate technology in recent years, it will be difficult to scale EOT well below 1 nm. This makes junction-depth scaling even more pressing for continued transistor scaling. Furthermore, as the dimensions of MOSFETs are scaled down, the contact resistance of...
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...Practices for Fire Safety (ELECTRICAL INSTALLATION) T.R.A. Krishnan SUBSTATION LAYOUT INDOOR Oil capacity inside oil filled equipment individual or aggregate 2,300litres or above. • Detached and shall be at least 6 m away from the surrounding buildings and/or occupancies. • If within 6 m - Single Fire Proof Doors for facing wall openings and 6 mm thick wired glass for facing window openings of substation. • Attached substations - 350 mm thick brick or 230 mm RCC common wall carried upto the roof with Single Fire Proof Door in wall openings -contd- SUBSTATION LAYOUT INDOOR • If attached Substation supplies power to Fire Pumps, common wall shall be a Perfect Party Wall (PPW) with Double Fire Proof Doors in the openings. • Separating walls [355 mm] required between transformers, carried 600 mm above the highest point if aggregate oil capacity is 2,300 liters or above. If fire pump supply is tapped from the transformer(s), walls are compulsory irrespective of oil contents. SUBSTATION LAYOUT INDOOR Oil Soak Pits to be if the oil capacity litres or above. Oil Soak Pits to be at least 2.5 m away Substation. provided is 2,300 provided from the SUBSTATION LAYOUT [OUTDOOR] If individual or aggregate oil capacity is 2,300 liters or above - to be located 6 m away from any building. Alternatively, external wall facing the transformers be a blank wall. Separating distances between the transformers are required as follows: * 2,300 upto 5,000 litres...
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...Table of Contents Page Executive Summary 2 Introduction 2 Mission 4 Conclusion 15 References 15 Table of Figures Figure 1 GSV 5 Figure 2 Refueler and Depot 7 Figure 3 Refueling Scenario 8 Figure 4 RSV 14 Table 1 Distribution of active satellites 4 Table 2 GEO Servicing opportunities 4 Table 3 GSV mass breakdown 6 Table 4 Power Budget 9 Table 5 Cost of Refueler/Depot 11 Executive Summary Launching a satellite into space with a mission to service other satellites is a plausible idea. Servicing a satellite means to somehow make it so a satellite’s design life is lengthened. This can be accomplished by refueling, assisting in orbit placement, and/or performing mechanical repairs. Satellite servicing has been done already in the past during manned space missions. The problem arises when the attempt is to be made on satellites outside of human intervention like those in High Earth Orbits (HEO). The ESA and d NASA have both put forth their ideas on how to service satellites in space. The Refueler/Depot idea suggested by NASA has the plan to launch a large satellite into space in two parts. One part is the Refueler, which is agile and movable and can dock with cooperating satellites. The other half is the Depot which stores the hydrazine fuel but remains in a constant orbit above the GEO belt. ESA’s idea is of a single satellite that will...
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