Window Breaks Research Articles

Exploratory backdraft experiments

This study is a qualitative exploration of backdraft phenomena. Backdraft is defined as a rapid deflagration following the introduction of oxygen into a compartment filled with accumulated excess pyrolyzates. A scenario describing the physical and chemical fundamentals underlying backdraft phenomena is presented. A half-scale apparatus, designed to avoid dangerous overpressures, was used to obtain data from backdraft experiments. A gas burner supplied a 150 kW natural gas fire in a 1.2 m high, 1.2 m wide, 2.4 m long compartment with a small, 25 mm high, 0.3 m wide vent to ambient at floor level. Significant unburnt fuel accumulates in 180 seconds, when a hatch covering a 0.4 m high, 1.2 m wide vent, centered on a short wall, is opened, simulating a window breaking due to thermal stresses. The propagation across the compartment of the cold density-driven flow, which enters through the new opening, is called a “gravity current.” This gravity current carries a flammable mixed layer to a spark located near the burner on the opposite wall. The rapid deflagration that results upon ignition of the mixed layer is the backdraft. A compartment fire model is used to calculate conditions in the compartment before the vent opens. The hypothesized scenario appears to be confirmed by the deflagrations and exterior fire balls observed in these preliminary experiments.

What Light Through Yonder Window Breaks? More Experiments in Atmospheric Physics.

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What Light through Yonder Window Breaks?—The Greenhouse Effect Revisited

What Light through Yonder Window Breaks?—The Greenhouse Effect Revisited

Political Institutionalization of Labor in Korea

P rofessor Theodore Lowi, current president of the American Political Science Association, once mused that democracy is essentially a system whose optimal outcome of accomplishment in reality can be and whose normative goal of achievement ought to be an incomplete conquest.' The incompleteness of conquest here alluded to concerns both the system input and the system stability. Thus, the politics of confrontation and window breaking is no more a virtue to an architect of a republic than the system of trains-running-always-on-time is an ideal to a liberal democrat. One of the greatest threats to democracy is the delicate balance between the quest for input and stability that derives from the character of its social change, and, perhaps more important, its pace. The process of Korean industrialization during the last three decades is something of a two-horned blessing. The breathtaking pace of Korea's social change that has compacted all of the ramifications of industrialization into less than one quarter of the total time that it took to accomplish elsewhere-roughly more than a century's duration, for example, in the United States-has extracted a number of heavy tolls. Among them, the grave threat to the necessary balance between the citizen input and the system balance. Part of the gargantuan task of obtaining and sustaining the democratic balance has to do with the very nature of an upwardly mobile society whose rate of mobility is exponential. An inventory of hardships that such a society must confront includes rapidly rising expectations and an acute sense of relative deprivation that pervade all corners of the community. For these twin phenomena constitute the greatest obstacles to a successful citizen education about the virtues of an incomplete conquest or democracy at its best. To the

Breaking of flat glass — Part 1: Size and distribution of particles from plain glass windows

An experimental rig was constructed, for the systematic breaking of windows, where a steel ball struck the pane in a controlled manner. For plain window glass the distance travelled by particles from the resulting debris was determined according to fragment size. The general form of the results agreed well with earlier findings. Replicate breakings were then performed to establish the reproducibility of the method. By combining the data for replicates for particular size ranges, smooth relationships were demonstrated between the number of particles and the distance travelled. The distribution of the glass particles radially, which was size dependent, was also studied.

Glass Breaking In Fires

Glass breaking in compartment fires is an important practical problem since a window acts as a wall before breaking and as a vent after breaking. If sufficient excess pyrolyzates have accumulated in the hot layer, this sudden geometric change can lead to backdraft and flashover. As Emmons explained at the First Symposium, windows break in fires due to thermal stress from the differential heating of the central portion and the shaded edge. The focus of this paper is on quantifying the connection between the compartment fire and the glass temperature to predict the window breaking time, tb. Techniques are presented for accurately calculating the history of the central glass temperature profile, T (x .r), for any fire exposure. Two-dimensional temperature histories, T (x ,y ,t), where x is depth and y is toward the center, and mean stress histories, azz (y ,t), are also calculated. It is determined here that breaking occurs when the mean glass temperature difference is ~T = (ablE ~)g, where ablE is the maximum glass tensile strain, ~ is the thermal coefficient of linear expansion and g is a geometry factorpf order one. Calculations suggest that the edge remains at its initial temperature, T; , so that ~T = T (tb) Ti, when the shading is large, sIL ~2, and the heating is fast, atb Is2::;1, where L is the glass thickness, s is the shaded edge width and «is the glass thermal diffusivity,

Transient Wind‐Induced Internal Pressures

The paper refers to a new experimental approach applied in a boundary layer wind‐tunnel experiment that tests the transient response of the wind‐induced internal pressure in a building when a sudden opening occurs. This topic has been examined analytically in the past. It has been found that the internal pressure may become much higher than the external pressure when a large window breaks during a windstorm. The present study examines this question experimentally by imposing a sudden opening on the front wall of a square building. The internal pressure was monitored at a number of points inside the model building, which could be tested at various internal volumes by using airtight partitions. A continuous record of the internal pressure variation was thus obtained while a data acquisition system was sampling it at a high rate to determine its statistics. The results of the experiments are compared with the analytically predicted data and form a basis to examine the influence of the air flow and the internal volume on the transient responses of the wind‐induced internal pressures in buildings.

Methodism and the mob in the eighteenth century

Early Methodism is often studied as an example of a popular religious movement, but the purpose of this paper is to explore some of the reasons behind its unpopularity, for suffering and persecution characterised its early phases as well as growth and success. The persecution of Methodists took many forms. Perhaps the hardest to bear were those least often recorded, such as the eviction of society members from their homes and jobs, or the unnerving social ostracism which made life intolerable in many villages and families. The persecution usually described in the journals of the methodist pioneers, however, was that inflicted by ‘the mob’. ‘The mob’ was an elastic term in their vocabulary and could range from a knot of village youths throwing stones to the ferocious urban crowds which cruelly assaulted worshippers in Exeter in 1745 and Norwich in 1752. ‘Mobbing’ too covered a gamut of activity. Much of it was rude horseplay, like the release of sparrows at the candles in a cottage meeting; some was petty malicious damage, like the breaking of windows. But not infrequently it erupted more violently. Preaching-houses at St Ives, Sheffield, Arborfield, Wolverhampton, Nantwich and Chester were pulled down, and others severely damaged. A number of houses, generally of poor people, were wrecked or sacked. Many persons, women and children among them, were cruelly beaten and some scarred or injured for life. A few, like William Seward, first blinded and then killed by a mob at Hay in 1741, paid for their beliefs with their lives. The knowledge of these ordeals, transmitted by biographies and oral tradition, gave the movement its equivalent of a martyrology and built up that image of heroic, primitive Methodism which, like the image of primitive Christianity itself, stimulated and reproved the piety of later, more comfortable generations.

New Zealand Earthquakes

ACCORDING to a bulletin just received from the Dominion Observatory, Wellington, twelve strong earthquakes were registered during February 1942 by the thirteen seismographic stations in New Zealand. The interpretation of many of the seismograms was hindered by microseisms, though it is thought that the earthquake of February 17, the preliminary waves from which arrived at Wellington at 04h. 18m. 24s. U.T., had its epicentre in the Coral Sea. A good deal of minor activity, which is expected in New Zealand, was recorded, and many local shocks were reported as having been felt by observers throughout the islands. The highest intensity reached was 6 on the Rossi-Forel scale (ringing of bells, stopping of clocks, breaking of windows, etc.), which occurred on two occasions: on February 21 at 22h. 23-9m. u.T., felt at New Plymouth, and on February 22 at 12h. 18-lm. u.T., felt at Whakatane and Opotiki, and followed by numerous minor shocks.

The Japanese School Question and the Treaty-Making Power

The Japanese protest of October 23, 1906, against the action of the San Francisco board of education, based on a California statute requiring all children of Mongolian descent to attend the school set apart for orientals, is one of the most puzzling incidents in our recent diplomatic history. It was sufficiently perplexing to the friends and admirers of Japan to learn that her government had created an international issue out of such a trivial matter as the segregation of less than one hundred Japanese pupils in the oriental school of San Francisco. But some of the friends and supporters of the administration were still more surprised to hear that the federal government admitted that the treaty of 1894 with Japan had been violated by this action of the San Francisco board of education, and apparently believed that it had jurisdiction in the premises.It is true that Secretary Metcalfe's report, which was published on December 19, 1906, also informed us of a considerable number of assaults on Japanese subjects by “hoodlums and roughs,” and of the breaking of windows in Japanese restaurants in San Francisco. These attacks, although subsequent to the earthquake, occurred at a time of great public disorder during which there appears to have been a carnival of crime when the police were powerless to protect life and property; but they seem to have been directed against the Japanese from motives of race prejudice, and not for the purpose of robbery.