Measurements of Smoke Characteristics in HVAC Ducts

The characteristics of smoke traveling in an HVAC duct have been observed along with the response of selected duct smoke detectors. The simulated HVAC system consists of a 9 m long duct, 0.45 m in diameter. An exhaust fan is placed at one end of the duct and is capable of inducing airflow rates that range from 0 to 1.5 m ³/s. The flow is controlled by means of a manual damper. On the upstream end of the duct there is a square exhaust hood approximately 2.2 m at the bottom and 0.3 m at the top. The bottom of the hood is approximately 2.5 m above the floor a shroud extends down to approximately 1.5 m above the floor. The test section, placed immediately downstream of the hood, is 3.5 m long duct with a square cross section of 0.4 m on a side. The instrumentation includes oxygen, carbon monoxide and carbon dioxide gas analyzers and a load cell to determine the energy release rate of the fires tested. The smoke within the duct is characterized by means of a laser light sheet and charge coupled device (CCD) camera, two white light source and photocell ensembles, a Pitot tube and an array of eight thermocouples placed on the vertical plane of symmetry. A smoke detector was placed at the downstream end of the test section. Two types of detectors were tested, ionization and photoelectric, with a single sampling probe geometry. The fires tested cover a wide range of fuels (propane, heptane, toluene, toluene/heptane mixture, shredded paper, polyurethane foam, wood cribs) with the peak energy release rates up to 800 kW. The smoke detector performance, temperature, flow field, smoke particle size and particle distributions are dependent on the fire characteristics and airflow through the duct. The different measurements could be scaled by means of the fire size and airflow rate but left a strong dependency on the fuel and burning characteristics (i.e., smoldering, flaming). The optical density and mass optical density are analyzed as metrics for characterizing smoke and smoke detector response. Detailed comparisons between the different metrics used are presented throughout this work. Clear evidence of stratification and aging of the smoke along the duct are also presented. The limitations of the present configuration and the need for a larger scale study are also discussed.     

Long Distance Enhancement of Nonlinear Optical Properties Using Low Concentration of Plasmonic Nanostructures in Dye Doped Monolithic Sol–Gel Materials

Monolithic sol–gel silica composites incorporating platinum‐based chromophores and various types of gold nanoparticles (AuNPs) are prepared and polished to high optical quality. Their photophysical properties are investigated. The glass materials show well‐defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts of the AuNP plasmon absorption peaks due to the increase in nanoparticle doping concentration are observed in the glasses, proving that no or very small SPR coupling effects occur between the AuNPs. At 600 nm excitation, but not at 532 nm, the AuNPs improve the nonlinear absorption performance of glasses codoped with 50 × 10^?3 m of a Pt‐acetylide chromophore. The glasses doped with lower concentrations of AuNPs (2–5 μm average distance) and 50 × 10^?3 m in chromophore, show a marked improvement in nonlinear absorption, with no or only small improvement for the more highly AuNP doped glasses. This study shows the importance of excitation wavelength and nanoparticle concentration for composite systems employing AuNPs to improve two‐photon absorption of chromophores.     

New wireless connection between user and VE using speech processing

This paper presents a novel speak-to-VR virtual-reality peripheral network (VRPN) server based on speech processing. The server uses a microphone array as a speech source and streams the results of the process through a Wi-Fi network. The proposed VRPN server provides a handy, portable and wireless human machine interface that can facilitate interaction in a variety interfaces and application domains including HMD- and CAVE-based virtual reality systems, flight and driving simulators and many others. The VRPN server is based on a speech processing software development kits and VRPN library in C++. Speak-to-VR VRPN works well even in the presence of background noise or the voices of other users in the vicinity. The speech processing algorithm is not sensitive to the user’s accent because it is trained while it is operating. Speech recognition parameters are trained by hidden Markov model in real time. The advantages and disadvantages of the speak-to-VR server are studied under different configurations. Then, the efficiency and the precision of the speak-to-VR server for a real application are validated via a formal user study with ten participants. Two experimental test setups are implemented on a CAVE system by using either Kinect Xbox or array microphone as input device. Each participant is asked to navigate in a virtual environment and manipulate an object. The experimental data analysis shows promising results and motivates additional research opportunities.     

Automatic discovery of interpretable planning strategies

Machine Learning - When making decisions, people often overlook critical information or are overly swayed by irrelevant information. A common approach to mitigate these biases is to provide...     

Information flows amongst executives: their implications for systems development

Senior managers have tended to resist the incursion into their personal domain of computer systems meant for their use. Their main criticism is that technical solutions are being imposed on them without an adequate analysis of the problems at hand. This suggests that the way in which executives obtain and exchange information may not be adequately understood. With the help of a framework designed to identify top executives' networks of information flows, the study reported in this paper analysed the information practices of 16 executives from four organizations. The findings of the research indicated that executives use a combination of communication flows and information flows in a proportion which varies depending upon the context of their different activities. It also revealed that executives initiated information and communication flows of a different nature depending upon the role they play and the level of those with whom they deal within the organization. The results of the study suggest that very specific approaches are needed when identifying executives' needs in terms of developing systems aimed at supporting top managers' strategic activities.     

A recognition network model-based approach to dynamic image understanding

In this paper, we present definitions for a dynamic knowledge-based image understanding system. From a sequence of grey level images, the system produces a flow of image interpretations. We use a semantic network to represent the knowledge embodied in the system. Dynamic representation is achieved by ahypotheses network. This network is a graph in which nodes represent information and arcs relations. A control strategy performs a continuous update of this network. The originality of our work lies in the control strategy: it includes astructure tracking phase, using the representation structure obtained from previous images to reduce the computational complexity of understanding processes. We demonstrate that in our case the computational complexity, which is exponential if we only use a purely data-driven bottom-up scheme, is polynomial when using the hypotheses tracking mechanism. This is to say that gain improvement in computation time is a major reason for dynamic understanding. The proposed system is implemented; experimental results of road mark detection and tracking are given.     

Further considerations on a cognitive problem-solving perspective on school consultation.

Addresses cognitive research in school consultation and critiques W. Pryzwansky (see record 1989-38304-001). Four topics are reviewed: (a) the present state of cognitively oriented research in consultation, (b) research on social-science problem solving and its extension to school consultation, (c) research on teachers' cognitions and decision making in the classroom, and (d) cognitive training strategies that can be applied to consultation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thiol‐mediated degradation of DNA adsorbed on a colloidal gold surface

When [³²P]‐labeled DNA is adsorbed on colloidal gold from a 130 mmol dm^?3 solution of KH₂PO₄, it can subsequently be eluted with cold DNA without undergoing detectable degradation. Similarly, DNA can be incubated in solution in the presence or absence of colloidal gold with high concentrations of β‐mercaptoethanol or hexane‐1‐thiol without significant degradation. However, when adsorbed DNA is eluted from gold with solutions of one of the thiols, it is recovered as a mixture of mononucleotides and short oligomers. The extent of degradation increases with increasing concentration of the thiol and with increasing elution temperature. Our results emphasize that in designing protocols involving DNA adsorbed on gold surfaces, it is important to avoid allowing the DNA to come into contact with even moderate concentrations of thiols. © 2003 Society of Chemical Industry