Method and apparatus for checking fire detectors

A fire detector checking method and device are disclosed for nondestructively verifying the operation of installed fire detectors of the type which operate on the principle of detecting the rate of temperature rise of the ambient air to sound an alarm and/or which sound an alarm when the temperature of the ambient air reaches a preset level. The fire alarm checker uses the principle of effecting a controlled simulated alarm condition to ascertain wheather or not the detector will respond. The checker comprises a hand-held instrument employing a controlled heat source, e.g., an electric lamp having a variable input, for heating at a controlled rate an enclosed mass of air in a first compartment, which air mass is then disposed about the fire detector to be checked. A second compartment of the device houses an electronic circuit to sense and adjust the temperature level and heating rate of the heat source

Detector for inspection of fire alarms

Portable detector tests rate-of-rise temperature devices. Incandescent light bulb is calibrated to produce rate of temperature rise necessary to activate properly functioning alarm

URBAN IMPACT UPON AGRICULTURE AND NONFARM ALTERNATIVES FOR LAND

Land Economics/Use,

Causal Domain Restriction for Eikonal Equations

Many applications require efficient methods for solving continuous shortest path problems. Such paths can be viewed as characteristics of static Hamilton-Jacobi equations. Several fast numerical algorithms have been developed to solve such equations on the whole domain. In this paper we consider a somewhat different problem, where the solution is needed at one specific point, so we restrict the computations to a neighborhood of the characteristic. We explain how heuristic under/over-estimate functions can be used to obtain a causal domain restriction, significantly decreasing the computational work without sacrificing convergence under mesh refinement. The discussed techniques are inspired by an alternative version of the classical A* algorithm on graphs. We illustrate the advantages of our approach on continuous isotropic examples in 2D and 3D. We compare its efficiency and accuracy to previous domain restriction techniques. We also analyze the behavior of errors under the grid refinement and show how Lagrangian (Pontryagin's Maximum Principle-based) computations can be used to enhance our method.Comment: 27 pages; 17 figures; accepted for publication in SIAM J. on Sci. Comp; (a minor update to address the reviewers' comments

AGRICULTURE AND NATURAL RESOURCES IN THE WEST: THE NEXT 100 YEARS

Resource /Energy Economics and Policy,

Summer music festivals

Looking for something fun to do this summer? What better way to have fun than check out some nearby festivals, or better yet, get a change of scenery and hit the road for some great live music

Formation Response of High Frequency Electromagnetic Waves

Core samples from rock formations respond to electromagnetic radiation based on an effective permittivity, which depends on the conductivity and permittivity of the constituent components of the rock, as well as the geometric structure of these constituents and the frequency of the radiation. This study analyzes the effect, for radiation of 1 to 100 Mhz, of discrete inclusions having a different permittivity from the surrounding medium. The focus is on the effect of certain geometric features, namely, the individual size of the inclusions, their overall volume fraction, the presence of sharp edges, and their aspect ratio. It is found that the volume fraction has the strongest impact on the effective permittivity, linear at first but higher order at higher volume fractions. The aspect ratio of the inclusions has a moderate effect, which is exaggerated in the extreme case of needle-like inclusions, and which can also be seen in a stronger nonlinearity. There is also a possibility that some features in the shape of the inclusion boundaries may influence the frequency dependence of the effective permittivity. Inclusion size and sharp edges have negligible effect

Adaptation maintains cortical visual processing at criticality

Previous studies, both theoretical and experimental, of network level dynamics in the cerebral cortex show evidence for a statistical phenomenon called criticality; a phenomenon originally studied in the context of phase transitions in physical systems and that is associated with favorable information processing in the context of the brain. The focus of this paper is on the role of criticality in visual sensory information processing. One line of previous work suggests that the dynamic range of the network, when presented with outside stimulus, is maximized at criticality. Another line of previous work suggests that adaptation to changes in visual input serves to improve dynamic range. A third line of work suggests that adaptation can bring about criticality. Taken together, these three previous ideas suggest that adaptation to visual input will bring about criticality. Thus, our hypothesis was that visually driven activity does operate near criticality, except during a transient period of adaptation immediately after the onset of the stimulus. We experimentally confirmed this hypothesis; we demonstrate that sensory driven cortex dynamics maintain signatures of criticality and in good agreement with our model; the transient response to the stimulus onset is not critical, but supercritical

Forced marriage of people with learning disabilities: a human rights issue

This paper reports some of the findings of an exploratory study which sought to better understand the demographics of forced marriage of people with learning disabilities and the contexts in which such marriages may occur. It was found that forced marriages of people with and without learning disabilities showed broad similarities in relation to ethnicity, some differences in terms of age and substantial differences in terms of gender. Men and women with learning disabilities are equally likely to be victims of forced marriage. The reasons for people with learning disabilities being forced to marry are most often associated with a desire on the part of families to secure permanent care, but can also be associated with cultural (mis)understandings of the nature of disability. These findings are contextualised by considering the relationship between forced marriage, human rights and learning disability