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Design Curves (design + curve)
Selected AbstractsResonance frequency of hexagonal and half hexagonal microstrip antennasMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009K. P. Ray Abstract Closed form expressions for the accurate calculation of the resonance frequency of a hexagonal and half hexagonal microstrip antennas, based on their equivalence with rectangular microstrip antenna, have been presented. These proposed empirical formulae have been validated using simulations and experiments. Design curves, for the input impedance variation along the feed axis, have been presented for hexagonal and half hexagonal patches for two feed positions. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 448,452, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24087 [source] Planning-level source decay models to evaluate impact of source depletion on remediation time frameREMEDIATION, Issue 4 2005Charles J. Newell A recent United States Environmental Protection Agency (US EPA) Expert Panel on Dense Nonaqueous Phase Liquid (DNAPL) Source Remediation concluded that the decision-making process for implementing source depletion is hampered by quantitative uncertainties and that few useful predictive tools are currently available for evaluating the benefits. This article provides a new planning-level approach to aid the process. Four simple mass balance models were used to provide estimates of the reduction in the remediation time frame (RTF) for a given amount of source depletion: step function, linear decay, first-order decay, and compound. As a shared framework for assessment, all models use the time required to remediate groundwater concentrations below a particular threshold (e.g., goal concentration or mass discharge rate) as a metric. This value is of interest in terms of providing (1) absolute RTF estimates in years as a function of current mass discharge rate, current source mass, the remediation goal, and the source- reduction factor, and (2) relative RTF estimates as a fraction of the remediation time frame for monitored natural attenuation (MNA). Because the latter is a function of the remediation goal and the remaining fraction (RF) of mass following remediation, the relative RTF can be a valuable aid in the decision to proceed with source depletion or to use a long-term containment or MNA approach. Design curves and examples illustrate the nonlinear relationship between the fraction of mass remaining following source depletion and the reduction in the RTF in the three decay-based models. For an example case where 70 percent of the mass was removed by source depletion and the remediation goal (Cg/C0) was input as 0.01, the improvement in the RTF (relative to MNA) ranged from a 70 percent reduction (step function model) to a 21 percent reduction (compound model). Because empirical and process knowledge support the appropriateness of decay-based models, the efficiency of source depletion in reducing the RTF is likely to be low at most sites (i.e., the percentage reduction in RTF will be much lower than the percentage of the mass that is removed by a source-depletion project). Overall, the anticipated use of this planning model is in guiding the decision-making process by quantifying the relative relationship between RTF and source depletion using commonly available site data. © 2005 Wiley Periodicals, Inc. [source] An assessment of hydraulic design of trickle laterals considering effect of minor losses,IRRIGATION AND DRAINAGE, Issue 4 2007Gürol Y canalisations d'eau; canalisations tertiaires; conception hydraulique; analyse; perte de charge Abstract The accurate design of trickle irrigation laterals needs to determine the total energy losses that includes the pipe friction losses along the lateral line and the local pressure losses, sometimes called minor losses, due to the protrusion of emitter barbs into the flow. Evaluation of energy losses is usually carried out by assuming the hypothesis that minor losses can be neglected, even if previous experimental studies indicated that minor losses can become a significant percentage of total energy losses as a consequence of the high number of emitters installed along the lateral line. In this study, a simple analytical procedure is presented to evaluate the effect of minor losses which is characterized by a coefficient ,i, expressing the amount of minor head losses as a fraction of the kinetic head, on trickle lateral design. According to both the design cases of without and including minor losses, the dimensionless design curves were developed for both the various lateral diameters and lengths. The results of two practical examples for designing either the diameter or the length indicated that, in some design cases, neglecting minor losses may lead to erroneous designs of the lateral diameter and length. This method is simple and easily adaptable to solve lateral hydraulic problems but sufficiently precise in comparison with the alternative procedures. The proposed equations are useful when applied for design and evaluation purposes and offer a practical field solution for laterals used in irrigation systems. Copyright © 2007 John Wiley & Sons, Ltd. La conception précise des canalisations tertiaires dans un système d'irrigation au goutte à goutte doit déterminer le total des pertes de charge qui viennent du frottement dans la canalisation elle-même mais aussi des pertes locales, parfois appelées pertes mineures, dues à la protubérance de barbes au niveau des goutteurs. Cette évaluation est normalement réalisée en considérant comme négligeables les pertes mineures, même si des études expérimentales ont montré que ces pertes mineures pouvaient constituer un pourcentage significatif de la perte de charge totale du fait du grand nombre de goutteurs installés le long de la canalisation tertiaire. Dans cette étude, une procédure analytique simple est proposée pour évaluer l'effet des pertes mineures sur la conception des canalisations tertiaires grâce à un coefficient ,i, exprimant le montant de ces pertes en une fraction de la charge cinétique. En fonction des diverses options de conception prenant ou non en compte les pertes mineures, des courbes de conception non dimensionnelles ont été tracées pour les diamètres et les longueurs des canalisations. Les résultats de deux exemples concrets montrent que, dans certains cas de conception, le fait de négliger les pertes mineures peut conduire à des conceptions de diamètre et de longueur erronées. Cette méthode est simple et facilement adaptable à la résolution de problèmes hydrauliques au niveau des tertiaires mais suffisamment précise par rapport des méthodes alternatives. Les équations proposées sont utiles pour la conception et l'évaluation et offrent une solution de terrain concrète pour les canalisations tertiaires utilisées dans des systèmes d'irrigation (au goutte à goutte). Copyright © 2007 John Wiley & Sons, Ltd. [source] Multi-objective optimization of venturi scrubbers using a three-dimensional model for collection efficiency,JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2-3 2003Gopalan Ravi Abstract Multi-objective optimization of a venturi scrubber was carried out using a three-dimensional model for collection efficiency and non-dominated sorting genetic algorithm (NSGA). Two objective functions, namely (a) maximization of the overall collection efficiency, and (b) minimization of the pressure drop were used in this study. Three decision variables including two operating parameters, viz liquid,gas ratio and gas velocity in the throat, and the nozzle configuration, which takes into account the three-dimensional nature of the problem, were used in the optimization. Optimal design curves (non-dominated Pareto sets) and the values of the decision variables corresponding to optimum conditions on the Pareto set for a pilot-scale scrubber were obtained. The liquid to gas (L/G) ratio, which is a key decision variable that determines the uniformity of liquid distribution, and a staggered nozzle configuration can produce uniform liquid distribution in the scrubber. Multiple penetration using nozzles of two different sizes in a triangular staggered arrangement can reduce liquid loading by as much as 50%, consequently reducing the pressure drop in the scrubber. © 2003 Society of Chemical Industry [source] Analysis of parallel coupled-line bandpass filters using a ground-plane apertureMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2005Zhenyu Zhang Abstract Parallel coupled-line bandpass filters using the ground-aperture technique are analyzed in this paper. A design guide and design curves for this kind of coupled-line bandpass filter on commonly used high- and low-permittivity substrates are presented. Based on the proposed design curves, two sample bandpass-filter configurations are designed. The design is simulated using Ansoft HFSS and validated by the measurements. Good agreement between the simulated and measured responses is obtained. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 237,240, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20781 [source] Full-wave FDTD design and analysis of wideband microstrip-to-waveguide transitionsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2003Càndid Reig Abstract Wideband transitions are designed and analysed by using two different approaches of the finite-difference time-domain (FDTD) method, in combination with the theory of nonuniform transmission lines. These transitions consist of a ridged waveguide-based taper between a shielded microstrip and a standard X-band rectangular waveguide. In the first step, a full-wave 2D-FDTD scheme is used to calculate the dispersion characteristics, as well as the geometry dependence of the impedance in the double ridged waveguide. Once these design curves have been obtained, the stepped transmission line transformer theory is used to design the tapers. In a former step, the nonuniform 3D-FDTD technique is applied, the transitions are simulated and the method is validated. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 317,320, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11048 [source] | ||||||||||