Large Amount Of Damage Research Articles

Detection of water deposits and movement in porous materials by infrared imaging

Since a large amount of damage in porous materials arises as a direct or indirect consequence of moisture (static and dynamic phenomena), detection and monitoring of moisture in porous materials is important, in an attempt to determine the actual damage, as well as the deterioration rate. The most common methodology to assess the moisture content in porous materials is to collect representative samples from the sites investigated and then weigh them before and after drying. In this research, infrared thermography, an indirect moisture assessment technique, was used in the investigation of various porous stones in the laboratory during capillary rise tests. Supplementary investigation of the stones in terms of their microstructure (mercury intrusion porosimetry) and isothermic behaviour (water sorption) was also performed. Finally, an in field diagnostic survey on historic structures was carried out. The results of this study indicate that infrared imaging provides significant information in the study of moisture in porous materials.

Risk assessment from debris flows in pyroclastic deposits along a motorway, Italy

This paper contains a quantitative estimate of the risk to life along the A3 motorway, Naples–Salerno. It examines a 1 km long section of the route between the towns of Pagani and Nocera Inferiore which passes below the northern slope of the St. Pantaleone hill. During the 38 years between 1960 and 1997 there have been four debris flows which have claimed two casualties, as well as a large amount of damage and injuries and resulted in the motorway remaining closed to the traffic for a long time. The annual probability of death of at least one occupant of a vehicle was calculated using the "event tree" analysis. The following assumptions have been made: the death probability was calculated only for accidents caused by the direct impact of a moving vehicle with landslide debris; the chance that more than one person could be present in the car during an accident was not considered; it was assumed that traffic is uniformly distributed in time. Over the 38-year period considered, the annual probability of occurrence of one fatality in a single accident due to crashes into landslide debris defines the unacceptable risk Results suggest that countermeasures are needed to reduce the risk along the entire section prone to debris flows when considering high traffic intensity.

Analysis of Accelerations from the 1 October 1995 Dinar, Turkey, Earthquake

The Dinar earthquake, 1 October 1995, occurred in southwestern Turkey and had a moment magnitude of 6.4 and a normal faulting mechanism. The earthquake caused 90 deaths, over 200 injuries, and a large amount of damage. It was recorded by seven strong-motion accelerographs. The strong-motion accelerograph at Dinar is on the edge of the surface projection of the fault. The record from Dinar is possibly unique in its proximity to the causative fault for this type of mechanism. The Dinar strong-motion station is in a small, stiff building on soft sediments with a shallow water table. The peak acceleration was 0.32 g on the horizontal component perpendicular to the fault trace. The earthquake was caused by rupture on the Dinar fault, which is a normal fault trending generally toward the south-southeast, with the hanging wall on the west. There was surface rupture along about a 12-km segment of this fault. The Dinar strong-motion station is at the south end of the fault, under 1 km from the nearest surface trace. The hypocenter was at the south end, beneath Dinar, with rupture propagating toward the north and away from the strong-motion site. A specific composite source model was found that reproduces the statistical characteristics of the ground motions and also approximately reproduces the low-frequency waveform in the strong motion. In this model the fault length, L, is 12.5 km, the width, W, is 17.3 km, and the moment M 0 is 4.72 × 10 25 dyne cm. The fault strikes 130° and dips 45° toward the southwest, from the surface to 12 km. For the composite parameters, the largest subevent ( R max ) is 4.0 km, the rupture velocity is 1.5 km/sec, and the subevent stress drop is 60 bars. After Anderson (1997) the composite source model parameters imply that the static stress drop was 36 bars, the radiated seismic energy in this event was 4.3 × 10 21 ergs, the apparent stress was 18 bars, and the Savage-Wood ratio was 1.0. Most of the seismic energy is released at depths greater than 2 km. The major asperity is beneath the location where synthetic aperture radar interferometry found the maximum surface deformation.

Carrier activation in in situ Si-doped GaAs layers fabricated by a focused Si ion beam and molecular beam epitaxy combined system

C– V carrier profiles for 200 eV and 30 keV Si FIB singly and doubly implanted and successively buried regions in GaAs using a FIB/MBE combined system were investigated to show a possibility of formation of doping layer above the 30 keV Si-implanted region which is desirable for formation of three-dimensional semiconductor nano-structures. It is found that carrier density in the 30 keV Si implanted and buried region was reduced near the projected range and the doping efficiency was less than half of that in samples fabricated by implantation without the successive burying after post-annealing. For the 200 eV and 30 keV doubly implanted sample, the peak carrier density for 200 eV Si was reduced by 40% compared with 200 eV single implantation. The present result suggests that large amount of damage may be remained in the implanted range and the post-annealing was less effective in the buried sample because of the existence of the overlayer-regrown cap layer.

Numerical simulation of dust explosions in pneumatic conveyors

Dust conveyors are used in a wide range of industrial applications. Explosions can be transmitted through dust conveyors to different parts of a processing facility and thus can cause a large amount of damage. In order to study the evolution of dust explosions in such conveyors, a numerical model was developed which combines a front tracking method with a solver for the Euler equations. In this model the effects of the chemical reactions and of the flow turbulence were summarized in the turbulent burning velocity of the dust-air mixture. This approach results in a large reduction of the computational effort and thus allows to study the influence of parameter variations. Here results are presented for corn starch-air mixtures. The numerical model was first calibrated by comparison with one set of experimental data. The model was then tested by comparison with different experimental data and the sensitivity of the model parameters is discussed. Finally calculations were performed for different dust concentrations, flow velocities and tube lengths.

Preliminary results of a macroseismic survey of the Colfiorito sequence (Central Italy)

Umbria-Marche region (Central Italy) has been interested by a seismic sequence, which caused a large amount of damage within an extensive area (around 5000 km2). The sequence produced eight shocks with magnitude higher than 5.0, the largest of them occurring on September 26, UTC 09:40, M1 = 5.8. The incidence of many shocks with a magnitude higher than 4.0 contributed to the creation of a damage pattern that was in evolution for more than one month. Such seismic behavior motivated field operators to perform a real-time macroseismic survey to update the data set. One of the major objectives was to differentiate the effects pertaining to each of the largest shocks. In this paper we present the macroseismic survey performed during the sequence, along with some preliminary results inferred. Intensity points of seven of the main shocks are shown, together with the filtered macroseismic fields produced following the application of specific statistical methods. Finally, consideration is given to the comparison of these study results with corresponding tectonic and geological data.

Thermo-Oxidative Stability and Fiber Surface Modification Effects on the Inplane Shear Properties of Graphite/PMR-15 Composites

Experiments were conducted to study the effects of thermo-oxidative stability (weight loss) and fiber surface modification on the inplane shear properties of graphite/PMR-15 unidirectional composites. The isothermal aging was conducted at 316°C and up to 1000 hours of aging times. The role of fiber surface treatment on the composite degradation during the thermo-oxidative aging was investigated by using A-4 graphite fibers having three different surface modifications, namely untreated (AU-4), surface treated (AS-4), and surface treated and sized with epoxy-compatible sizing (AS-4G). Weight loss of matrix, fibers, and composites was determined during the aging. The effect of thermal aging was seen in all the fiber samples in terms of their weight loss and reduction in fiber diameter. Calculated values of weight loss fluxes for different surfaces of rectangular unidirectional composite plates showed that the largest weight loss occurs at those cut surfaces where fibers are perpendicular to the surface. Consequently, the largest amount of damage was also noted on these cut surfaces. Optical observation of neat matrix and composites plates subjected to the different aging times revealed that the degradation (such as matrix microcracking, void growth, etc.) occurred within a thin surface layer near specimen edges. The inplane shear modulus of the composites was unaffected by the fiber surface treatment and the thermal aging. The shear strength of the composites having the untreated fibers was the lowest and it decreased with aging. Fracture surface examination of the composites having untreated fibers suggests that the weak interface allows the oxidation reaction to proceed along the interface and thus expose the inner material to further oxidation. The results indicate that fiber-matrix interface affects the composite degradation process during its thermal aging and that the weak interface accelerates the composite degradation.

Application des statistiques de Weibull à la caractérisation des résines phénoliques et des matériaux composites SMC

The flexural failure strengths of phenolic resin and a range of SMC composites based on this resin, are considerably higher than the failure strengths obtained from tensile tests. A statistical approach based on the Weibull distribution is applicable to brittle materials such as phenolic resins, which are subject to size effect. On the other hands, SMC materials n which short fibers are randomly oriented, accumulate a large amount of damage before failure, so that such a distribution is not applicable owing to the presence of multiple ailure origins

NOTES ON THE HABITS OF ATTACK OF THE HEMLOCK BORER

The hemlock borer (Melanophila fulvoguttata Harr.) belongs to a buprestid genus, the larvae of which bore in the bark and cambial area of the stems of conifers. They generally breed in trees which have been weakened. injured, or recently felled. Several species, however, including fulvoguttata, are reported to be capable of attacking and killing healthy trees and doing a large amount of damage. In other words, they belong to that class of cambial feeders which normally finds conditions most favorable when the host is about to die, but occasionally appears to be capable, when numerous, of breeding in healthy trees which would otherwise live. They are faculative tree killers.

An Analysis of Some of California's Major Entomological Problems

Because of the great variety of crops grown commercially in California, the economic entomologist must specialize to a large degree in order best to serve. There is much waste and injury in the use of insecticides when a proper scientific basis for action is lacking. In this, both the farmer and the entomologist are often at fault. An unbiased investigation of the fundamental principles of insect control will in some instances at least, reveal astonishing discrepancies in our present methods of procedure. Intensive laboratory experiments coupled with carefully planned field investigations are essential. Thus experiments with newly hatched codling moth larvae which attack both the apple and English walnut in California, indicate that the efficacy of lead arsenate in protecting apples in particular against side entrances and stings has been greatly overestimated. Greater attention to orchard and packing house sanitation is urged. With what appears to be a gradual development of resistance of the black scale of oranges to hyrocyanic acid gas and the well known resistance of the citrus red spiders to the same gas, oil sprays are now being used quite extensively in the citrus areas of California. A strong tendency to use oil sprays against red spiders on prunes is evident in many parts. The use of oil sprays presents many difficult problems such as possible injury to the tree and discoloration of the fruit, but much trouble has already been obviated by the development of a quick breaking emulsion of highly refined lubricating oils. The large amount of damage done by the garden centipede to asparagus and that of certain soil infesting nematodes has created a strong demand for soil fumigants. It has been found, however, that the damage to asparagus done by the garden centipede can be entirely overcome by proper flooding where that is possible. On the other hand, an effective soil fumigant is now available in the xanthates which are valuable when properly employed on account of the decomposition product, carbon disulfide. Sugar beets, one of the pioneer crops of California, have been threatened for some years by a disease known as curly-top which is carried by a very small leafhopper. The control of this insect presents much difficulty on account of its migratory habits. Cotton is one of the newer crops of California but is already valued at over $10,000,000. To keep this crop free from the pests so prevalent in the South is one of our problems, and to prevent native insects from transferring their affections from wild vegetation to this valuable crop is another. California beekeepers have long disagreed as to the nectar value of the California buckeye. It is now known that when severe droughts curtail the nectar possibilities of other plants and bees are compelled to use the buckeye alone, poisoning of the bees is pretty sure to follow, while mixed with nectar from other plants, that of the buckeye is harmless. Similar climatic peculiarities limit the use of top minnows (Gambusia) in anopheline mosquito control. Great differences in topography within a short distance, likewise ocean and desert influences within a narrow range, greatly influence climate and make it dangerous to generalize in control recommendations.

Two Pests of Mahogany in Nyasaland

Mahogany trees are attacked by two caterpillars which inflict a large amount of damage every year. One of these, Heteronygmiu leucogyna, Hmp. (Lymantriidae), eats the leaves, while the other, Mussidia albipartalis, Hmp. (Pyralidae), bores under the bark, causing much deformity of young trees and the formation of corky excrescences, accompanied by the exudation of resin.

“Fox-shark” or “Thrasher” (Alopecias vulpes) in the English Channel

ON July 2 a fine specimen of this shark was captured several miles south of the Eddystone Lighthouse by fishermen in search of mackerel. The fish was taken at a depth of about 40 fathoms, and did a large amount of damage to the mackerel nets before it could be hauled on board and killed. The shark was brought to the Plymouth Museum and purchased for the collection.

The Severe Gale of November 11

THE storm which traversed England on November 11 was one of the most severe of recent years. It resulted in considerable loss of life and property at sea on our coasts, and did a large amount of damage on land.