Window Configurations Research Articles

Phase change measurement, sound speed and attenuation determination from underwater acoustic panel tests

Material measurements in underwater acoustics are employed regularly for characterization of materials used as acoustic windows. Various techniques have been developed to measure the acoustic attenuation magnitudes of materials. Recently, there has been increased interest in window configurations of complex geometries and of phase response of that material to an acoustic wave. This latter phase parameter can be of high significance for acoustic devices composed of an array of elements. Thus, the phase response of the attenuation is needed to properly characterize material performance on the overall system. This translates into a primary need to measure the complex acoustic attenuation of panels at various angles of incidence. This paper summarizes the methodology to measure the complex attenuation of materials. Case examples of test materials measured will be presented; comparisons to theoretical response will be provided. Considerations given to rigging and required acoustic settling times are discussed. Expansion of the methodology that incorporates a causal relationship between the measured phase response and attenuation to the sound speed of the material will be developed. The model relating these parameters and their implementation via an iterative least squares fitting of the parameters to the measurement data will be discussed.

Optimized Energy Window Configuration for 201Tl Imaging

A poor signal-to-noise ratio attributable to a low injected dose of thallium and the presence of scattered photons are the major impediments in the use of thallium as an imaging agent. Thallium decays in a complicated way and emits photons in a wide range of energies (68-82 keV). To increase the ratios of primary photons to scatter photons (primary-to-scatter ratios) and possibly increase system sensitivity, a new energy window for thallium was investigated. The NCAT phantom was used to simulate the distribution of activity and the attenuation coefficient in a typical patient torso. The phantom was imaged with a SPECT simulator in different energy window configurations. The energy spectra for primary photons and scatter photons were generated, and the most suitable energy windows were investigated. To evaluate the results of the simulation study, a physical phantom was imaged in different energy windows with a SPECT system. The images of the physical phantom were analyzed for the best-quality image and the corresponding window setting. To evaluate the windows determined in the simulation and phantom studies, SPECT images of 7 patients who had angiographically confirmed myocardial defects were acquired in different energy windows. The images were quantitatively compared on the basis of the calculated contrast, scatter-to-noise ratio, and sensitivity. The images were also qualitatively evaluated independently by 4 nuclear medicine specialists. The simulation study showed that the conventional window setting (68 +/- 10% keV) is not the most suitable window configuration for (201)Tl imaging and that the optimum energy window is 77 +/- 15% keV. The images acquired in the latter window configuration yielded higher primary-to-scatter ratios, higher sensitivity (total counts), and better contrast than the images acquired in the conventional window configuration. The phantom study confirmed the results of the simulation study. In the clinical study, the images acquired in the suggested window showed a considerable increase in myocardium-to-defect contrast (1.541 +/- 0.368) and myocardium-to-cavity contrast (1.171 +/- 0.099) than those acquired in the conventional window configuration. The energy window configuration of 77 +/- 15% keV yields higher-quality images than the conventional window configuration.

Heavy density liquid metal spallation target studies for indian ADS programme

Department of Atomic Energy, India has taken up the development of ADS in view of many attractive features like inherent safety, capability to transmute large quantities of nuclear waste, better utilization of thorium etc. A roadmap has been finalized for the development of ADS. One of the key components of the ADS is the spallation target. Considering the neutron yield, thermal-hydraulics and radiation damage issues, we are proposing to develop spallation target based on heavy density liquid metals like lead and lead-bismuth-eutectic (LBE). Both window and windowless target configurations are presently being studied. In view of the various advantages we are also studying liquid metal flow circulation based on gas lift mechanism. An R&D programme has been initiated to address various physics and technology issues of ADS target. Under this programme, mercury and LBE experimental facilities are presently being set up. Along with these facilities, computational tools related to spallation physics (FLUKA) and CFD are being developed, and the existing ones are utilized to design the entire target loop as well as sub-systems. In this presentation the details of these activities are presented.

Use of ventilated solar screen window in warm climate

In the building façade, window glazing is one major element contributing to the space thermal load. Lots of work has been done on developing advanced glazing systems that are energy efficient under various climatic conditions. One new concept is the ventilated solar screen window. In this paper, the possible use of this new concept in the warm climate is discussed. A numerical model of a ventilated window system was developed and this was extended to model additional four window configurations. The heat flow was then analyzed for office hours based on the TMY weather data of Hong Kong. The simulation results indicate that better saving can be achieved with the use of ventilated window in summer, in which the outdoor air is induced as the ventilating air stream. In winter, the internal thermal load is high enough to counteract the heat loss through the building envelope. Hence in the warm climatic region, the reversible mechanism is not required for the ventilated window to switch between the summer and winter operation mode. This can save the window construction cost as well as the labor cost for the seasonal changeover.

Optimized acquisition and processing protocols for I-123 cardiac SPECT imaging

Deconvolution of septal penetration (DSP) has been developed to improve quantification so as to allow the use of low-energy high-resolution collimators for iodine 123 cardiac single photon emission computed tomography (SPECT) imaging. The purpose of this study is to optimize its acquisition and processing protocols. Planar images of a 9-compartment phantom loaded with variable radioactive concentrations were acquired to derive optimal scatter compensation scaling factors for 20% and 15% photopeak energy window configurations, respectively. A cardiac phantom, loaded with high and low heart-to-calibration ratios (HCRs), respectively, was imaged with both configurations. Repeated acquisitions were done for medium-energy all-purpose collimators for comparison. Critical frequencies for Butterworth filtering were optimized by use of defect contrast and normal short-axis uniformity as selection indices. HCRs were calculated with planar projection and different reconstruction methods, respectively, and then compared with the true HCRs. SPECT produced more accurate HCRs than planar imaging. With the optimized parameters for scatter compensation and filtering, the 2 energy window configurations yielded similar results. Iterative reconstructions with DSP yielded more accurate HCRs than other reconstructions without DSP. The optimized protocols based on DSP show promise that quantification of I-123 cardiac SPECT imaging can be achieved with the widely available low-energy high-resolution collimators.

AIR EXCHANGE RATE IN A HORSE TRAILER DURING ROAD TRANSPORT

Horses traveling by road commonly experience heat stress conditions and poor air quality, which may be caused by insufficient ventilation; however, there are few estimates of air exchange in a horse trailer during transport. Air exchange rate was measured at ten locations within a four-horse trailer (internal volume 18.5 m3) using tracer gas decay measurement to assess the adequacy of ventilation. Three vehicle speeds (13, 48, and 97 km h-1) and three window configurations (all windows and roof vents closed, all windows open, all windows open and roof vents open forward) were tested with and without animals present in the trailer. External air temperature ranged from 22.3°C to 28.3°C with an average of 25.3°C, and internal air temperature ranged from 29.9°C to 34.8°C with an average of 31.3°C with animals present. Air exchange rate increased with vehicle speed and open window and vent area. The average air exchange rate over all vehicle speeds and ventilation configurations was 0.52 min-1 with animals present and 0.76 min-1 without animals. Without animals present, the maximum mean exchange rate was 1.42 min-1 at 97 km h-1 at the rear left window with all windows and vents open; the lowest mean exchange rate was 0.12 min-1 at 13 km h-1 with all windows and vents closed at the lower position of the rearmost stall divider. With animals present, the maximum air exchange rate observed was 0.84 min-1 with all windows and vents open and traveling at 97 km h-1. Ventilation in the trailer was not adequate when compared to recommendations for stabled horses for any combination of vehicle speed or ventilation configuration. Increasing open vent area, either by increasing the number and size of roof vents or the size of windows in the sidewall, would be the most cost-effective means of increasing air exchange in a horse trailer.

Evaluation of models for the angular variation of solar absorptance in windows

Abstract An empirical model to predict the angular variation of solar absorptance in window panes has been evaluated in terms of errors in maximum absorbed solar power. The input to building simulation programs is usually the near normal optical properties of a window, and the angular variation has to be predicted by some kind of algorithm. This may lead to an incorrect estimate of the solar optical properties. In this study, Fresnel formalism and international standards for the solar irradiation were used when calculating the error in the total solar absorptance in window panes using different approximations. The absolute error in maximum absorbed solar power was then calculated for a standard Stockholm climate and for four different orientations (N, E, S, W) for the incidence angle intervals 0 – 10 ° , 10 – 20 ° , … , 80 – 90 ° . Typically, the highest values for maximum incident power on a vertical facade in the Stockholm climate are found for incidence angles around 20° for all four orientations, whereas the absorptance of many types of window panes peaks at about 70–80°. Together, the two effects give a maximum absorbed solar power at an angle between these two values. The empirical model requires that the window composition is known and thereby to which of the nine groups the window belongs. A set of polynomial fits for the angular absorptance is used; one set for each window group (one polynomial fit for each window pane). It is shown that the error with the empirical model, which distinguishes between different window configurations, is on average about a factor of ten lower than with two other models where the same approximation is used indiscriminately for all windows.

Antireflection treatment of low-emitting glazings for energy efficient windows with high visible transmittance

The objective of this study is to increase the visible transmittance of a low-emittance (low-e) glazing as much as possible by antireflection treatment. This has been carried out by depositing thin porous films of silicon dioxide, SiO 2, on both sides of a commercial glazing with a pyrolytic low-e tin oxide-based coating. SiO 2 was chosen because its refractive index makes it suitable for antireflection treatment of both the uncoated glass side and the side of the tin oxide coating. The deposition of the antireflective films was performed with a dip-coating method, where the substrate was dipped in a sol–gel of silica. Two different silica sol–gels were used, one was manufactured in the laboratory and the other one was a commercial solution with a higher porosity. An increase of the integrated visible transmittance ( T vis) by 9.8% points up to 0.915 was achieved for a coating produced with the commercial solution. Calculations of U value, g value and T vis for window configurations were also performed.

Optimization of architectural design elements in tropical humid region with thermal comfort approach

The air temperature and humidity combined in the enthalpy have a strong impact on the perceived air quality, and perceived air quality determines the required ventilation in ventilation standard. In tropical humid climate, which is mainly characterized by an elevated air temperature and a high relative humidity, obtaining the comfort conditions in the buildings can make by permitting sufficient interior air velocity. Air movements inside a building depend not only on external wind velocity, but also a number of architectural design element. This study aims to find out the effect of architectural design in naturally ventilated building to obtain thermal comfort in tropical humid regions. The applicability of some architectural design elements such as type and location of window, balcony configuration, and interior division was assessed using numerical simulation. The analysis shows that balcony, most window configurations and interior division plays a significant role in modifying the indoor thermal condition but it does not always need a higher air speed.

A NUMERICAL STUDY OF THE EFFECT OF WINDOW CONFIGURATION ON THE EXTERNAL HEAT AND SMOKE SPREAD IN BUILDING FIRE

This article presents a numerical study of external heat and smoke spread caused by compartment fires in multistory buildings. Usually, a building fire causes not only hazard to the occupants in that compartment, but also poses a possible threat to the occupants in other compartments, in particular to those located at upper stories. In this study, three scenarios with different window configurations are performed on the basis of the Navier–Stokes equations and the standard k– k model. Analysis of the computational results found that the window configurations and area as well as its location affect the heat and smoke pattern and in turn the safety of the occupants at upper stories. This implies that window design for multistory buildings, in terms of fire safety, should be carefully considered.

Double window configuration as a low cost microwave waveguide window for plasma applications

Waveguide windows are major components of a transmission line used in microwave plasma devices. The function of the waveguide window is to provide vacuum isolation of the source side from the plasma chamber while transmitting microwaves with minimum attenuation. Commonly a single thin dielectric plate is sandwiched between a choke type flange and a flat flange and is used as a waveguide window. To arrive at a better window configuration in terms of the low power reflection coefficient, the voltage standing wave ratio calculation is carried out for different window configurations (single window and double window) and for various window thicknesses. It is found that the power reflection is the minimum in the case of double window configuration. The minimum power reflection is as low as 0.8% for a combination of alumina and a quartz plate each of 1 cm thickness in the double window configuration. Also, it is more advantageous to use radial microwave coupling than axial coupling in order to increase the life time of the microwave waveguide window.

Window and roof configurations for comfort ventilation

This paper assesses the applicability of some architectural design elements to provide comfort ventilation in humid tropical regions: size and location of windows, building eaves and roof shapes for a single unit house. Most window and roof configurations are sufficent to produce only a slightly more comfortable level although they can certainly increase the indoor air velocity. The improvement of indoor air velocity can minimize the physiological effect of the high humidity. Among the tested models, the room with a high gable roof combining with eaves improves significantly the indoor air velocity. Cet exposé évalue l'applicabilité de certains éléments de configuration visant à assurer une ventilation de confort daus les régions tropicales humides: dimensions et emplacement des fenêtres, formes d'avant-toit et de toiture pour une maison individuelle. La plupart des configurations de fenêtre et de toiture suffisent seulement a fournir un minime supplément de confort, bien qu'elles puissent effectivement améliorer la circulation intérieure de l'air. Une amélioration de circulation intérieure de l'air peut atténuer les effets physiologiques d'une forte humidité. Parmi les modèles essayés, le local comportant une toiture à pignon élevé associée à des avant-toits offre une nette amélioration de circulation interieure de l'air.

Optimum edge detection in SAR

Different window configurations and measures for detecting edges between regions of different mean in synthetic-aperture radar (SAR) images are compared. Two criteria for optimisation are considered: (i) maximising the total probability of detecting an edge within a window; and (ii) maximising the accuracy with which the edge position can be determined. Clearly, an ideal edge detector would combine both properties. Maximum-likelihood solutions to the two criteria are discussed and it is shown how they determine the choice of both window configuration and the measure adopted. The performance degradation encountered when the tests are applied to the scenario for which they are not optimised is compared and the test which best meets both original criteria is identified. Combination of the good features of each to yield the best overall performance in a two-stage edge-detection scheme is discussed.

Transmission Spectra of an Electrochromic Window Based on Polyaniline, Prussian Blue and Tungsten Oxide

The demand for energy savings in buildings will increase in the coming years, as the world's attention is drawn towards environmental aspects and energy economizing. Windows which are able to dynamically control the sun radiation through‐put will play an important role. In this respect we have studied two different electrochromic window configurations; one based on the two complementary electrochromic materials polyaniline (PANI) and tungsten oxide , the other one with the electrochromic coating Prussian blue (PB) in addition to PANI and . The inclusion of PB enhances the transmission modulation. Integrating over the solar spectrum we find that the window based on PANI and is able to regulate 39% of the total solar energy, while with the inclusion of PB we manage to regulate as much as 50% of the sun radiation.

A Numerical Study Of Window-to-window Propagation In High-rise Building Fires

This study describes numerical simulations of high-rise building fires extending to upward floors via windows. Flames and gases ejected from openings and flowing along vertical building exterior walls may fracture window glasses and accelerate the fire growth towards upper floors. Particularly, there have been no numerical studies of dynamic fire behavior around windows and along vertical exterior walls, in relation to the fire growth. Here is attempted numerical finite-difference studies of time-dependent flow behavior of fires along external building walls and of the behavior of fires invading into the upper floor windows. Two-dimensional numerical simulations show that upward flows adhere closely to the wall surface, similarly to the experimental flow patterns. Some large scale vortices are created around the upward fire gases. Almost periodically, hot gases enter the room immediately above the fire room via windows. The regular oscillatory motion depends upon the heat release rate in the fire room and is weakly ~ffected by the window configurations.

Spatial frequency difference thresholds depend on stimulus area

Spatial frequency difference thresholds were estimated for vertical, high contrast 5.0 cpd sinewave gratings that had been multiplied by a two dimensional Gaussian window function of contrast. A range of different elliptical window configurations were tested that varied in their relative height and width. Spatial frequency acuity improved as the area of the target was increased. The data are compatible with a model of spatial frequency discrimination that is based on statistical averaging of spatial intervals interpolated between local retinal signs.

Painless panes for Smalltalk windows

Current windowing systems (i.e., Macintosh, Smalltalk) give the user flexibility in the layout of their computer display, but tend to discourage construction of new window types. Glazier is a knowledge-based tool that allows users to construct and test novel or special purpose windows for Smalltalk applications. The use of Glazier does not require understanding Smalltalk's windowing framework (Goldberg, 1984; Goldberg & Robson, 1983). As a new window is specified, Glazier automatically constructs the necessary Smalltalk class, and methods (programs). Windows are interactively specified in a Glazier window - the user specifies type and location of panes through mouse motions. Panes can contain text, bit-maps, lists, dials, gauges, or tables. The behavior of a pane is initially determined by Glazier as a function of the pane type and related defaults. These default behaviors allow the window to operate, but do not always display the application information desired. In that case, the user can fix the window's behavior by further specification. Such alterations require only knowledge of the application, not of the windowing system. Glazier allows the prototyping and development of full-fledged Smalltalk windows, and allows a flexibility that will change window usage in two ways. First, it will allow end users to construct special purpose windows for viewing data from an application in manners unanticipated by the system designers. Second, system developers will be encouraged to prototype and evaluate many window configurations before settling on a final choice. Both alternatives will result in windows that are more satisfying to the end-user. The makeup of Smalltalk or Macintosh-style windows is typically viewed as a fixed component of the computer interface. Windows are provided to the end user by the system designer and cannot be customized. Sadly, users are not allowed the flexibility of their window contents that windows allow for display contents. Thus, the user is forced to use windows that may not precisely fit the needs for his or her use of the application. Of course, the option of adding new windows is available to some users. A skilled Smalltalk user can construct a special-purpose window in an afternoon. Completion of such a task requires detailed knowledge of Smalltalk's model-view-controller (MVC) paradigm (Goldberg, 1984; Goldberg & Robson, 1983). This is perceived as an inconvenient, tedious task and is hardly something a novice Smalltalk programmer can or should attempt. This paper discusses Glazier, a tool that encapsulates knowledge about building Smalltalk windows, and assists a user in developing new Smalltalk windows. Glazier works as an assistant, relieving the user from the burden of thinking about windowing details. Instead, the user needs only to understand how to operate the data structures for the application being displayed by the window. Window development now becomes a symbiotic process, Glazier provides the knowledge on how to build the window and the user provides knowledge about how the application is used and how the window should behave. There are a numerous other systems to support interface development in a like manner. Bass (1985) describes a system for developing VT100 style interfaces on top of base-level applications. The system supports a wide range of user needs, but cannot be configured dynamically by the user. The Trillium System (Henderson, 1986) supports prototyping of copying machine interfaces and allows designers to build and test control panels. Other user interface management systems support construction of front ends for applications (Hayes, Szekely, & Lerner, 1985). None of these systems, however, has provided the user or developer with a dynamic environment for building generic windows. Glazier allows a user to build a wide range of window types, and use them as they are being built. This paper will discuss the operation of the Glazier, the method for constructing windows, and finally the implications of this new window construction technique.

Mechanical reliability of ceramic windows in high frequency microwave heating devices

The mechanical reliability was evaluated for the specific alumina and beryllia ceramics now used as microwave windows in the high-power (⩾200 kW) high-frequency (⩾60 GHz) gyrotron tubes being developed for plasma heating in fusion systems. Previous analysis of the stresses generated in the various window configurations and tube operating conditions indicated that significant tensile stresses are generated in the ceramic window by dielectric heating. As a result, we characterized both the static fatigue behaviour in the fluorocarbon fluid used to cool gyrotron windows and the inert strength distributions for these two ceramics. These data were then analysed in order to construct reliability diagrams for these two materials. Such diagrams revealed that the use of these specific ceramic materials will be limited by their time to failure at the tensile stresses imposed on them under the gyrotron operating conditions (60 GHz or greater and ⩾200 kW in a continuous wave (CW), TE02 mode (i.e., radial power distribution in beam exhibits two maxima). The fatigue behaviour and inert strengths of both materials could be improved by increasing their density (>97% of theoretical) and employing a uniform fine (⩽10μm) grain size. Such material improvements would permit significant increases in the mechanical reliability of the gyrotron microwave window.

Vehicle Warning Devices—Necessity versus Nuisance

Acoustical warning devices may be essential for public safety and a nuisance to nearby residents. The question arises, how much reduction in the level of the warning device can be tolerated before it loses its value as a warning signal? This paper presents the results of a short study related to possible reduction in acoustic level of a Diesel-engine horn. The important variables that were studied included (a) level and spectral content of the horn signal; (b) distance between Diesel engine and the driver of an automobile approaching a railroad crossing; (c) whether the automobile windows are open or closed; (d) the level of the masking sound the driver is experiencing. Use is made of the critical-bandwidth concept to obtain allowable Diesel-engine horn sound reductions for several automobile window configurations and three types of masking sounds.

The Apple Grove 750-kV Project- 500-kV Switching Surge and Line Flashover Tests

Rational design of extra-high-voltage systems depends on analytic studies to predict switching surge overvoltage magnitude and probability, and on laboratory tests for tower system switching surge withstand capability. Laboratory tests have been confined to ideal waveforms applied to single window configurations. Correlation with flashover performance of a typical 3-phase installation exposed to actual switching surge waveforms is attempted. The influence of interphase coupling and multiple circuit breaker operations in promoting multiphase flashover, which may curtail system performance margins, is also studied.