Influence of fire source locations on the actuation of wet-type sprinklers in an office fire

An experiment is conducted on a full-scale model office and an actual sprinkler system to explore the influence of fire source locations on sprinkler actuation. The office space is a brick structure that measures 5.7 m in interior length, 4.7 m in width and 2.4 m in ceiling height, and equipped with a sprinkler system. The investigated fire source (100 kW LPG burner) locations include the room center, wall centers, room corner, and other locations at different distances from sprinklers. The results show that actuation of the sprinklers is affected by the fire source locations and the heat conduction properties of the glass temperature-sensing bulb. Average actuation time of all the tests is 102 s, around 40 s faster than if the fire source is located in the room center. For fire sources in corners, sprinklers are quickly activated at the experimental time 75 s, showing concentrated hot gas flow.     

Horizontal Roadway Curvature Computation Algorithm Using Vision Technology

Abstract: Horizontal roadway curvature data are essential for roadway safety analysis. However, collecting such data is time‐consuming, costly, and dangerous using traditional, manual surveying methods. It is especially difficult to perform such manual measurement when roadways have high traffic volumes. Thus, it would be valuable for transportation agencies if roadway curvature data could be computed from photographic images taken using low‐cost digital cameras. This is the first article that develops an algorithm using emerging vision technology to acquire horizontal roadway curvature data from roadway images to perform roadway safety assessment. The proposed algorithm consists of four steps: (1) curve edges image processing, (2) mapping edge positions from an image domain to the real‐world domain, (3) calibrating camera parameters, and (4) calculating the curve radius and center from curve points. The proposed algorithm was tested on roadways having various levels of curves and using different image sources to demonstrate its capability. The ground truth curvatures for two cases were also collected to evaluate the error of the proposed algorithm. The test results are very promising, and the computed curvatures are especially accurate for curves of small radii (less than 66 m/200 ft) with less than 1.0% relative errors with respect to the ground truth data. The proposed algorithm can be used as an alternative method that complements the traditional measurement methods used by state DOTs to collect roadway curvature data.     

Concentrations of ultrafine particles at a highway toll collection booth and exposure implications for toll collectors

Research regarding the magnitude of ultrafine particle levels at highway toll stations is limited. This study measured ambient concentrations of ultrafine particles at a highway toll station from October 30 to November 1 and November 5 to November 6, 2008. A scanning mobility particle sizer was used to measure ultrafine particle concentrations at a ticket/cash tollbooth. Levels of hourly average ultrafine particles at the tollbooth were about 3-6 times higher than those in urban backgrounds, indicating that a considerable amount of ultrafine particles are exhausted from passing vehicles. A bi-modal size distribution pattern with a dominant mode at about < 6 nm and a minor mode at about 40 nm was observed at the tollbooth. The high amounts of nanoparticles in this study can be attributed to gas-to-particle reactions in fresh fumes emitted directly from vehicles. The influences of traffic volume, wind speed, and relative humidity on ultrafine particle concentrations were also determined. High ambient concentrations of ultrafine particles existed under low wind speed, low relative humidity, and high traffic volume. Although different factors account for high ambient concentrations of ultrafine particles at the tollbooth, measurements indicate that toll collectors who work close to traffic emission sources have a high exposure risk.     

Experimental Investigation of an Office Fire with a Partially Impaired Sprinkler System

In this work, an actual office fire with a partially impaired automatic sprinkler system was investigated. As per regulations, there were four sprinklers in this model office. In the research conducted here, the first three sprinklers were actuated without water supply, while the last sprinkler was supplied with water at the required operating pressure for a period of 30 min. The fire source, a burning plastic trash can filled with 0.5 kg of paper, burned the adjacent chair, desk, desktop computer, and then reached the interior wooden furniture. The results show that the single remaining sprinkler effectively controlled the fire spread for 30 min. The partially impaired sprinkler system does not completely extinguish the fire, but extends the available time for evacuation. Continuing the discharge from sprinklers is preferable since the heat release from the fire increased after water flow was terminated.     

Simulation of ultrasonic-vibration drawing using the finite element method (FEM)

In ultrasonic-vibration drawing, wires are drawn while ultrasonic vibration is applied to a drawing die. Prior studies provide experimental proof that ultrasonic-vibration drawing reduces drawing resistance, improves lubrication and prevents wire breakage. In the future, ultrasonic-vibration drawing is expected to contribute to the drawing of difficult-to-draw materials and operations, such as shaped wires, ultrafine wires, and the wire drawing operation in semidry or dry condition. However, a detailed analysis and understanding of the mechanism of improvement is not possible on the basis of conventional experimental observations because the ultrasonic-vibration processing phenomenon occurs at high speed. Therefore, we attempted to understand the processing mechanism of ultrasonic-vibration drawing using the finite element method (FEM). ABAQUS was used for the FEM. Drawing force and stress–strain distributions in drawn wires were analyzed. From these studies, we quantitatively clarified the mechanism of improved drawing characteristics, such as decreased drawing force.     

Optical properties and carrier dynamics of self-assembled GaN/Al(0.11)Ga(0.89)N quantum dots

GaN quantum dots were grown on an Al(0.11)Ga(0.89)N buffer layer by using flow rate modulation epitaxy. The Stranski-Krastanov growth mode was identified by an atomic force microscopy study. The thickness of the wetting layer is about 7.2 monolayers. The temperature dependent photoluminescence studies showed that at low temperature the localization energy, which accounts for de-trapping of excitons, decreases with the reducing dot size. The decrease in emission efficiency at high temperature is attributed to the activation of carriers from the GaN dot to the nitrogen vacancy (V(N)) state of the Al(0.11)Ga(0.89)N barrier layer. The activation energy decreases with reducing dot size.     

The lateral load-deformation response of RC walls with a consideration of the height–length ratio

Reinforced concrete (RC) walls play an important role in resisting earthquakes, so understanding the lateral load-deformation response of an RC wall subjected to an axial load, shear, and moment is essential to nonlinear structural analysis. In this study, the moment-bending deformation response of an RC wall under an axial load and moment is obtained from moment–curvature analysis using the wall’s proper plastic hinge length. Furthermore, modified compression-field theory, adjusted according to the height–length ratio of the wall, is used to calculate the shear–shear deformation response of the wall under an axial load and shear. By integrating the moment-bending deformation and the shear–shear deformation responses, the lateral load-deformation response of the RC wall under axial load–moment–shear interaction can be reasonably determined. To confirm the reliability of the proposed method, experimental results for 67 RC walls are compared with analysis results from the proposed method. The statistical results show that the proposed method accurately predicts the lateral ultimate load but somewhat underestimates the lateral ultimate deformation. Finally, this paper gives an example using an equivalent column to simulate an RC wall using SAP2000 pushover analysis.     

Workflow re-engineering of design-build projects using a BIM tool

The use of design-build delivery methods and building information modeling (BIM) tools in the construction industry has been growing rapidly in recent years due to the increasing demand for more efficient construction project management. The successful implementation of these?tools by engineering firms on projects, however, is still not being achieved consistently. This paper shares the experiences of the implementation of an in-house BIM tool by a large engineering, procurement, and construction firm that has an extensive reputation for design-build projects. A new workflow was proposed that takes full advantage of the BIM tool to both enhance the construction management performance and to minimize the impact on the firm’s existing workflow. The development of a new workflow was conducted by interviewing key personnel in various departments of the firm and by carefully examining probable impacts of the BIM tool’s introduction into the firm’s business processes.     

Characterization of PAHs exposure in workplace atmospheres of a sinter plant and health-risk assessment for sintering workers

This study first measured concentrations of polycyclic aromatic hydrocarbons (PAHs) in four selected workplace atmospheres, including the raw materials inlet, sintering grate, rough roll shredder and control room, and the outdoor environment of a sinter plant. Then, PAHs exposures and their resultant health-risks were assessed for sintering workers. We found that total PAH concentrations of the three selected sintering process areas were higher than that of the control room. The above results could be explained by the filtration effect of the air conditioning device installed inside the control room. PAH homologue distributions of the three selected sintering process areas were significantly different from that of the outdoor environment suggesting that PAHs found in the sintering workplace atmospheres were mainly contributed by process fugitives. Total PAH exposure levels were lower than the current permissible exposure limits, thus revealing that sintering workers are not a high risk group for long-term effects attributable to PAHs. Moreover, the lung cancer risks associated with the above PAH exposures were lower than the significant risk level defined by US Supreme Court further confirming that their exposures could be acceptable at this stage.