engineering strategies and practice i ii

... states differ qualitatively in their basic Trang 11species compositions, but within a state a similar species composition exists, thoughin quantitatively different combinations The alternative stable-state ... AND ECOLOGICAL ENGINEERING The inherent qualities of ecological engineering — the combination of science andengineering and the goal of designing and studying ecosystems that have neverexisted before ... available for analyzing ecological engineering? What are the ramifications of ecological engineering in developing countries with differing values and cultures? How do we institutionalize ecological

Ngày tải lên: 06/07/2014, 14:20

... Jimenez, and G Mirabelli 1993 Costa Rica’sconservation program and National Biodiversity Institute (INBio) pp 53–67 In: Biodiversity Prospecting W V Reid (ed.) World Resources Institute, Washington, ... engineering: a discipline whose time has come Engineering Education 80:15–18. Johnson, A T and W M Phillips 1995 Philosophical foundations of biological engineering Journal of Engineering Education 84:311–318. ... date Soil bioengineering: an introduction Unpublished course materials.Soil Bioengineering for Streambank, Shoreline and Slope Stabilization Short Course 1996, Rutgers University, New Brunswick,

Ngày tải lên: 06/07/2014, 14:20

... image as shown in the figure From equations B12 and B13 the electric field intensity, in this case, at point P is given as (B14) and non-uniformity factor is (B15) Figure B3 Cylindrical conductor—plane ... equation we get (B11) Now, by using equation B8 for potential, the potential difference between points P and Q is given as By putting the values of s1 and s2 in the above equation and simplifying, ... electric field intensity at a distance r is given by (B1) where e is permittivity of medium The potential reckoned from a distance R is (B2) The resultant potential at point A (figure B1) due to line

Ngày tải lên: 07/08/2014, 21:21

... used silicon-based liquid for insulation and cooling Due tonon-toxic dielectric and self-extinguishing properties, it is selected as areplacement of Askarel High cost of silicon is an inhibiting ... againstpollution and dirt - Vertical machines for winding large capacity transformer coils - Isostatic clamping for accurate sizing of windings - High frequency brazing for joints in the windings ... capacitive VARs generated during low loads and switching operations in extra high voltage transmissionnetworks, thereby maintaining the voltage profile of a transmission line withindesirable limits

Ngày tải lên: 07/08/2014, 21:21

... from limb to yoke along thegrain orientation in mitred joints minimizing losses in them For airgaps of equallength, the excitation requirement of cores with mitred joints is sin α times thatwith ... type) is more common and has the following distinct advantages:viz construction is simpler, cooling is better and repair is easy Shell-typeconstruction, in which a cross section of windings in the ... mm is provided on both the surfaces of laminations, which is sufficient towithstand eddy voltages (of the order of a few volts).Since the core is in the vicinity of high voltage windings, it is

Ngày tải lên: 07/08/2014, 21:21

... distribution is notuniform (different ampere-turn densities), the windings are divided into suitablesections so that the ampere-turn distribution in each section is uniform A typicalconfiguration ... transformer winding having uniform ampere-turn distribution in LV and HV windings As the number of harmonics is increased, the variation ofradial flux density becomes smooth, indicating the higher accuracy ... two-winding transformer Each winding is interlinked withthe leakage fields of other windings, and hence a load current in one windingaffects voltages in other windings, sometimes in a surprising

Ngày tải lên: 07/08/2014, 21:21

... solution satisfying this equation iswhere γ is defined by equation 4.32 In comparison with equation 4.65, equation 4.80 has two terms indicating waves traveling in both +z and -z directions (which ... making an angle of θ with the H axis as shown in figure 4.2 The significance of complex permeability is that a functional relationship between B and H is now realized in which the permeability is ... infinitely long in the x direction The current density J x and magnetic field intensity H y are assumed as functions of z only. Rewriting the (diffusion) equation 4.15 for the sinusoidal variation

Ngày tải lên: 07/08/2014, 21:21

... method is given in [13] for estimating leakage field, in which any kind ofcurrent density distribution can be resolved into space harmonics by a doubleFourier series The leakage field distribution ... flitch plate, the formulation is modified by consideringthat the plate is split into distinct parts A more accurate 2-D/3-D FEM analysis isreported in [34], in which many limitations of analytical ... are similar to those given in [4] wherein a general formulation is given for the estimation of losses in a structuralcomponent for any kind of spatial distribution of the incident magnetic field.Let

Ngày tải lên: 07/08/2014, 21:21

... force is taken by the outer winding, and the remaining 75 to 67% is taken by the inner winding Calculation of axial forces in the windings due to the radial field in non-idealconditions is not ... the amount of insulation is quite significantalong the axial direction, which is easily compressible With the axial forcesacting on the system consisting of the conductor and insulation, the naturalfrequencies ... an assumption is made that the entire heatdeveloped during the short circuit is retained in the winding itself raising itstemperature This assumption is justified because the thermal time constant

Ngày tải lên: 07/08/2014, 21:21

... rating Thedifference between the initial and final (linear) distributions sets up oscillations inthe winding According to Weed’s principle [17], a winding will be non-oscillating if the capacitive ... core/tank/other windings Thus, the initialvoltage distribution is characterized by the distribution constant, (7.12) This parameter indicates the degree of deviation of the initial voltage distributionfrom ... is obvious that the strength of the transformer windings to lightningvoltages can be significantly increased if the difference between the initial andfinal distributions can be minimized This not

Ngày tải lên: 07/08/2014, 21:21

... consists of basically internal insulation within thewindings, viz inter-turn and inter-disk insulation The chapter gives in details themethodology of design of the major and minor insulations in transformers.Various ... Affecting Insulation Strength The breakdown voltage of a dielectric material is a statistically distributedquantity which is a function of its physical/chemical properties and impuritiespresent in ... insulationand minor insulation The major insulation consists of insulation betweenwindings, between windings and limb/yoke, and between high voltage leads andground The minor insulation consists

Ngày tải lên: 07/08/2014, 21:21

... In this case, strict dimensional control ofpipes and other fittings is required in order to avoid oil leakages.Oil is kept in circulation by the gravitational buoyancy in the closed-loopcooling ... thickness bears a specific relationship with the radial depth ofwinding For a given radial depth, a certain minimum thickness of radial spacers isrequired for effective cooling (otherwise resistance ... oil circulation The heat is finally transmitted either to atmosphericair or water In the subsequent sections, modes of heat transfer and theirapplication in different cooling configurations in

Ngày tải lên: 07/08/2014, 21:21

... Design 393 Plain tank: The plain tank of rectangular shape is quite simple in construction. It is easy from design and manufacturing points of view since it facilitates standardization. The design ... winding details, design insulation details of accessories (bushings, radiators, fans, pumps, protection devices, etc.), weight and size limitations during transport and at site, etc. The designer ... specified by the standards. The tank design and fabrication are complicated due to limitations imposed by transportation (weight and size), requirement that the oil quantity should be optimum,

Ngày tải lên: 07/08/2014, 21:21

... is inversely proportional to permittivity in a multi-dielectric system. Since the permittivity of oil is about half of solid insulation, the stress in oil is more under the AC voltage condition ... conditions the voltage distribution is in direct proportion to resistance or electric stress is directly proportional to resistivity. At lower temperatures the resistivity of solid insulating ... special characteristics of rectifier transformers. 11.1.1 Bridge connection One of the most popular rectifier circuits is three-phase six-pulse bridge circuit as shown in figure 11.1. It gives

Ngày tải lên: 07/08/2014, 21:21

... cooling is used It is reported that the dielectric, mechanical and thermal design of windings can be done independently giving more flexibility for optimizing these functions It is also claimed ... short circuit condition is done in [24] by coupling magnetic field and electric circuit equations Analysis of load-controlled noise is done in [25] by using a formulation in which the magnetic and ... pressboard with low permittivity (around that of oil) is developed and if it is commercially made available, a more uniform electric stress distribution can be obtained opening avenues for insulation

Ngày tải lên: 07/08/2014, 21:21

... backbone cabling to the main distribution facility. Host/load requirements Minimum bandwidth requirements of users and servers. IDF (intermediate distribution facility) Secondary communications room ... identification. Define frame filtering, frame tagging, and frame identification. Frame filtering examines particular information about each frame. A filtering table is developed for each switch; ... Electrical and Electronic Engineers (IEEE) standards group because of its scalability. Frame tagging is gaining recognition as the standard trunking mechanism; in comparison to frame filtering, it...

Ngày tải lên: 21/12/2013, 05:18

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Ngày tải lên: 21/02/2014, 13:20

... Ecosystem Soil bioengineering Fast growing riparian tree species for bank stabilization and erosion control Bioremediation Mixes of microbial species and/ or nutrient additions for enhanced biodegradation ... Saddle River, NJ. With permission. 32 Ecological Engineering: Principles and Practice The trickling filter is a fascinating ecosystem because of its ecological complex- ity and its well-known engineering ... ecological engineering a unique kind of engineering and an intel- lectually exciting new kind of applied ecology. Many practical applications of ecological engineering exist, though often with different...

Ngày tải lên: 15/03/2014, 18:20

... upon the scientific principles involved. Besides specific courses and laboratories in corrosion prevention and control, additional courses in physical chemistry, electrochemistry, chemical thermodynamics, ... schematically in Fig. 3.3. In Fig. 3.3, a piece of zinc immersed in hydrochloric acid solution is undergoing corrosion. At some point on the surface, zinc is transformed to zinc ions, according ... one oxidation and one reduction reaction is not always as obvious as it is in chemical power cells and batteries. The two reactions are often combined on a single piece of metal as it is illustrated...

Ngày tải lên: 02/04/2014, 15:46

... SYSTEMS ENGINEERING PRINCIPLES AND PRACTICE SECOND EDITION Alexander Kossiakoff William N. Sweet Samuel J. Seymour Steven M. Biemer A JOHN WILEY & SONS, INC. PUBLICATION ffirs02.indd iiiffirs02.indd ... academic engineering disciplines. Engineering disciplines are built on quantitative relationships, obeying established physical laws, and measured properties of materials, energy, or information. ... EDITION xix PREFACE TO THE FIRST EDITION xxiii PART I FOUNDATIONS OF SYSTEMS ENGINEERING 1 1 SYSTEMS ENGINEERING AND THE WORLD OF MODERN SYSTEMS 3 1.1 What Is Systems Engineering? 3 1.2 Origins...

Ngày tải lên: 07/04/2014, 04:01