Wavefront Research (United States)

No AccessCity Development Strategy17 Dec 2020Greater Than PartsA Metropolitan OpportunityAuthors/Editors: Shagun Mehrotra, Lincoln Lewis, Mariana Orloff, Beth OlberdingShagun Mehrotra, Lincoln Lewis, Mariana Orloff, Beth Olberdinghttps://doi.org/10.1596/34820SectionsAboutPDF (18.1 MB) ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked In Abstract: Globally, cities are the source of over 70 percent of the world's greenhouse gas emissions. Cities are also the engines of the global economy, concentrating more than half the world's population, and they are where the middle class is rapidly expanding. Indeed, by the year 2050, two-thirds of the world will be urban, with cities accommodating an additional 2.5 billion people over today's total. Nearly all of this urban growth will occur in developing countries. This concentration of people and assets also means that the impacts of natural disasters, exacerbated by the changing climate, may be even more devastating, both in terms of human lives lost and economic livelihoods destroyed. These effects will disproportionately burden the poor. Earth is on a trajectory of warming more than 1.5 degrees Celsius unless important decarbonizing steps are taken.Often urban policymakers prescribe integration as the solution to steering urbanization towards decarbonization to achieve greater global and local environmental benefits. However, little is known about the struggles—and successes—that cities in developing countries have in planning, financing, and implementing integrated urban solutions. The main objective of this report is to understand how a variety of developing and emerging economies are successfully utilizing horizontal integration—across multiple infrastructure sectors and systems—at the metropolitan scale to deliver greater sustainability. This report explores how integrated planning processes extending well beyond city boundaries have been financed and implemented in a diverse group of metropolitan areas. From this analysis, the report derives models, poses guiding questions, and presents three key principles to provoke and inspire action by cities around the world. Previous bookNext book FiguresreferencesRecommendeddetails View Published: November 2020 Copyright & Permissions Related TopicsEnvironmentUrban Development KeywordsURBANIZATIONURBAN PLANNINGPOPULATION DENSITYSUSTAINABLE DEVELOPMENT GOALS PDF DownloadLoading ...

The general electromagnetic properties and design methodology for serpentine/folded-waveguide (FW) amplifiers are presented. In addition, hybrid-waveguide circuit topologies, which permit greater design flexibility than the basic serpentine/FW topologies, are also introduced, and their dispersion characteristics are discussed. Experimental validation of design methodology and tools is provided via test results of the recently demonstrated wideband 220-GHz serpentine amplifier, which embodies the design methodology described herein. Particular attention will be paid to the comparison between code prediction and experimental data, which are in excellent agreement.

The noise reduction effectiveness of acoustic mesh septa caps in composite honeycomb sandwich panels was evaluated. The acoustic mesh in the cells acted as a lightweight resonator in weight-critical aerospace structures. Nylon mesh was inserted into they honeycomb cells of the sandwich panels and the acoustic absorption (AA) and transmission loss (TL) of the panels was measured using a normal incidence impedance tube. Single septa inserted into each cell yielded consistent improvements of 2dB in TL over low to mid-frequencies (50-1600Hz). A double layer of septa further increased these acoustic properties in the mid-frequency range by an additional 2dB. Varying the size of the mesh-weave had a significant effect. Acoustic absorption of the panels improved by a factor of 2 for the single septa and was further increased by perforating the panel facesheet. Results of the facesheet perforation were consistent with predicted values. Over low to mid-frequencies, septa yielded measurable sound-mitigating results for a small weight addition with no change to the' mechanical performance of the panels.

— In this paper, an LCD backlight with holographic diffusers as the top diffuser was investigated. Using a suitable elliptical holographic diffuser, the moire pattern was eliminated and the brightness of the backlight was increased up to 15% compared to that for a backlight with a conventional diffuser. A Monte Carlo simulation was also applied to compare with the experimental results. In addition, elliptical diffusers can be applied to modify the viewing cone of the backlight.

The circle polynomials of Zernike are a vital tool in the analysis of optical systems. Decomposition of wavefronts into Zernike polynomials can be insightful. Computation in the Zernike basis, however, is quite cumbersome and inefficient. This paper will address how rational polynomials such as Zernike, Laguerre, Legendre and Chebyshev can be represented as affine combinations of a Taylor monomial set. This paper also demonstrates the efficiency of common routines using a Taylor basis as well as implementation and optimization issues.

Dit is bekend dat 'n goeie wortellengte en/of worteldigtheid in die eerste paar weke belangrik is om goeie saailingvestiging te verkry. Die doel van hierdie studie was om die uitwerking van minimumbewerking (wisselgangskotteleg en vlerkskaar), beitelploeg- en konvensionele bewerking op die groei van koring ten opsigte van vroeë wortelontwikkeling en biomassa te evalueer. Hierdie bewerkingsbehandelings is oor 'n periode van drie jaar op 'n Avalon sandkleileemgrond in die Sentraal-Vrystaat uitgevoer. Grondwaterinhoud was tydens plant dieselfde vir elke bewerking, behalwe vir geringe verskille in die boonste grondlae. Carina het die hoogste graanopbrengs (1 571 kg ha−1) gelewer by wisselgangskottelegbewerking in 1992, terwyl Molen in 1993 die hoogste graanopbrengs (2 462 kg ha−1) gelewer het by vlerkskaarbewerking. Die wortelontwikkeling en biomassa gedurende 1992 en 1993 toon dieselfde tendens waar Carina die grootste wortellengte en -massa in 1992 gehad het, maar in 1993 het Scheepers 69 en Carina geen verskille ten opsigte van wortelontwikkeling en biomassa getoon nie. Geen afleiding ten opsigte van watter bewerkingsbehandeling die wortelontwikkeling bevoordeel kan gemaak word nie. Die resultate dui wel daarop dat kultivars ten opsigte van vroeë wortelont-wikkeling verskil.