Borated polyethylene - fire properties and other issues

The scope and objective of this work was to evaluate and determine fire properties for a material that will be used for radiation shielding at the research centre. Traditionally two materials, borated paraffin and borated polyethylene, are used for radiation shielding at neutron-based research laboratories. Since base paraffin and base polyethylene are known as combustible materials with a high energy content it is of great interest to determine the actual fire properties of the borated versions

Experimental comparison of Q-fog and residential sprinklers in a residential fire scenario

In this report, the effectiveness of a detector-activated water mist system, Q-fog, has been compared to traditional residential sprinklers. In total, eight tests were performed with a realistic fuel (bed with pillow and duvet) based on the test procedure described in LPS 1655. The bed was placed at different locations in the room and was ignited at the pillow and below the bed, also according to LPS 1655. Temperatures were measured using six thermocouples at different locations and heights. Also, near field heat flux was measured using plate thermometers.The results show that the detector-activated water mist system seems to be superior when the fuel package is located in front of the suppression system, and the fire starts on top of the bed. If the fire starts below the bed or if the bed is located in a less favorable location, the performance is similar to traditional sprinklers. Finally, if the fuel package is both located in an unfavorable location and ignition occurs below the bed, the traditional sprinkler is superior. However, few fatal fires start below the bed and therefore, the overall effectiveness can be expected to be higher for the detector-activated water mist compared to the bulb-activated sprinklers

The Importance of Interfaces: A HW/SW Codesign Case Study

This paper presents a codesign case study in image analysis. The main objective is to stress the importance of handling HW/SW interfaces more precisely at the system level. In the presented case study, there is an intuitive and simple HW/SW interface, which is based upon the functional modules in the application. However, it is found, that this seemingly sound choice caused a number of practical problems and sub-optimal solutions during the implementation of the proto type system. 1. Introduction In this paper we will concentrate on the interface problems, as they evolved during the implementation of a HW/SW codesign case study for image analysis. The application was chosen both for its speed up potential, when realised as a mixed HW/SW system, and from a seemingly well defined separation in modules with precise interface specifications. The intention was to use this realistic and computationally challenging example as a relative simple test bench in the development of codesign meth..

Temporal knowledge discovery in big BAS data for building energy management

With the advances of information technologies, today's building automation systems (BASs) are capable of managing building operational performance in an efficient and convenient way. Meanwhile, the amount of real-time monitoring and control data in BASs grows continually in the building lifecycle, which stimulates an intense demand for powerful big data analysis tools in BASs. Existing big data analytics adopted in the building automation industry focus on mining cross-sectional relationships, whereas the temporal relationships, i.e., the relationships over time, are usually overlooked. However, building operations are typically dynamic and BAS data are essentially multivariate time series data. This paper presents a time series data mining methodology for temporal knowledge discovery in big BAS data. A number of time series data mining techniques are explored and carefully assembled, including the Symbolic Aggregate approXimation (SAX), motif discovery, and temporal association rule mining. This study also develops two methods for the efficient post-processing of knowledge discovered. The methodology has been applied to analyze the BAS data retrieved from a real building. The temporal knowledge discovered is valuable to identify dynamics, patterns and anomalies in building operations, derive temporal association rules within and between subsystems, assess building system performance and spot opportunities in energy conservation.Department of Building Services EngineeringDepartment of Computin

Influence of variable oxygen concentration on the combustion derived release of radiocesium from boreal soil and peat

Radiocesium, 137Cs, is one of the most common and dispersed human-made radionuclides. Substantial stocks of 137Cs are stored in organic layers, like soils and peat, as a consequence of nuclear weapons fallout and accidental releases. As climate warming progresses these organic layers are subject to enhanced risks of wildfires, especially in the vast boreal biome of the northern hemisphere. Reemission of 137Cs to the atmosphere is therefore presumed to increase. Here, we experimentally investigated the emissions and redistribution of 137Cs in smoldering fires of boreal soil and peat by varying the oxygen concentration during combustion. For both soil and peat, significantly more 137Cs was released through flaming combustion in 21% O2 (50% and 31%, respectively) compared to smoldering in reduced O2 environments (14% and 8%, respectively). The residual ashes were heavily enriched (>100%) in 137Cs. Hence, after a wildfire induced volatilization of 137Cs, there exists further pathways of 137Cs enriched ash to proliferate in the environment. These results serve as a link between wildfire combustion conditions and the mobility of the 137Cs inventory found in ground fuels of the boreal environment and can be valuable for radiological risk assessments in a warmer and a more nuclear energy reliant world