5,970 research outputs found
Building envelope design for climate change mitigation: a case study of hotels in Greece
This paper presents results of a study of the impact of future climate change scenarios as developed by the Intergovernmental Panel on Climate Change and implemented in weather files for specific future time slices (2020, 2050 and 2080) for the three climatic regions of Greece on the design of the external envelope of a hotel building in Greece. The impact of climate change on the hotel is assessed via hourly simulations of a calibrated model developed using the software TRNSYS. Additionally, the paper aims to identify optimal refurbishment strategies, given the constraints of the existing case-study building when transposed to the three different climatic zones in Greece. Two modes of the hotel building were studied: âall yearâ and âseasonallyâ operated. It was found that different external envelope energy-efficient strategies can be applied depending on the climatic zone and whether the hotel is all-year or seasonally operated
Airborne Measurements of Gravity Wave Breaking at the Tropopause
2000 FLORIDA AVE NW, WASHINGTON, DC,
2000
A follow-up study of 100 reading disability cases, now adults, who were associated with the Boston University Education Clinic between 1936-1948
Thesis (Ed.M.)--Boston Universit
Beam Diffraction by a Planar Grid Structure at 93 GHz
The idea of using diode grids for electronic beam steering was introduced by Lam et al [l]. As shown in Figure 1, when an incident beam reflects off the diode grid, the direction of the reflected wave can be controlled by progressively varying the ref1ection phase across the grid. The reflection phase of the diode grid can be controlled by varying the DC bias
on the diodes. Later, a monolithic diode grid was fabricated with l600 varactor diodes, and a relative phase shift of 70° at 93 GHz was measured [2]. This work verified the transmission-line theory used to design the grid, but the phase shift was not sufficient to steer the beam, recently, Johansson [3] designed and built a passive planar grating reflector antenna that focused a beam. A rigorous moment-method solution was applied to choose a grating geometry to select the first-order diffracted wave. In this work, using
the transmission-line model approach, the goal was to demonstrate that the beam can be steered by building a grid structure without diodes to give a fixed beam shift. In these grids, diodes were replaced by gaps with different sizes to obtain different capacitances needed to steer a beam at 93 GHz. The result show a successful beam shift of 30° with a loss of 2.5 dB
Site Factors Affecting Growth of Slash Pine in the Texas Post Oak Belt
A study was conducted in the Post Oak Belt of East Texas to determine which site factors affected height growth of slash pine (Pinus elliottii Engelm.). Height-age pairs were developed from stem analysis data. Nonlinear regression was implemented to develop a generalized height-age model. After curves were developed, stepwise regression was used to determine impacts of environmental variables on height growth. Environmental factors correlated with height growth included A horizon depth and those related to moisture relations including seasonal precipitation, average daily temperature, and texture of the A horizon. South. J. . Appl. For. 21(2):71-74
An evaluation resource for geographic information retrieval
In this paper we present an evaluation resource for geographic information retrieval developed within the Cross Language Evaluation
Forum (CLEF). The GeoCLEF track is dedicated to the evaluation of geographic information retrieval systems. The resource
encompasses more than 600,000 documents, 75 topics so far, and more than 100,000 relevance judgments for these topics. Geographic
information retrieval requires an evaluation resource which represents realistic information needs and which is geographically
challenging. Some experimental results and analysis are reported
Site Factors Affecting Growth of Loblolly Pine in the Post Oak Belt
A study was conducted in the Post Oak Belt of East Texas to determine which site factors affected height growth of loblolly pine (Pinus taeda L.). Height/age pairs were developed from stem analysis. Nonlinear regression was implemented to develop generalized height-age model. After curves were developed, stepwise regression was used to determine if an environmental variable impacted height growth. Environmental factors correlated with height growth included A horizon depth and those related to moisture relations including seasonal precipitation, average daily temperature, and texture of the A horizon. South.J. Appl. For. 16(4):197-20
A 100-element planar Schottky diode grid mixer
The authors present a Schottky diode grid mixer suitable for mixing or detecting quasi-optical signals. The mixer is a planar bow-tie grid structure periodically loaded with diodes. A simple transmission line model is used to predict the reflection coefficient of the grid to a normally incident plane wave. The grid mixer power handling and dynamic range scales as the number of devices in the grid. A 10-GHz 100-element grid mixer has shown an improvement in dynamic range of 16.3 to 19.8 dB over an equivalent single-diode mixer. The conversion loss and noise figure of the grid are equal to those of a conventional mixer. The quasi-optical coupling of the input signals makes the grid mixer suitable for millimeter-wave and submillimeter-wave applications by eliminating waveguide sidewall losses and machining difficulties. The planar property of the grid potentially allows thousands of devices to be integrated monolithically
- âŠ