Objects deteriorated

During exploitation, the polymer products suffer deformation and friction effects, and finally these ones are destroyed, as effect of gradual accumulation of some structural modifications that diminish their resistance to repeated deformations. Two are the most important reasons of finite objects deterioration 1) polymer ageing ... 

The mechanical performance of equipment is likely to deteriorate with use due to wear, corrosion, erosion, vibration, contamination and fracture, which may lead to failure. Since this would threaten a typical production objective of meeting quality and quantity specifications, maintenance engineering provide a service which helps to safely achieve the production objective. 

The very high powers of magnification afforded by the electron microscope, either scanning electron microscopy (sem) or scanning transmission electron microscopy (stem), are used for identification of items such as wood species, in technological studies of ancient metals or ceramics, and especially in the study of deterioration processes taking place in various types of art objects. 

The various chemical and physical processes that play a role ia the deterioration of art objects are not restricted to the present, even though the contemporary environment has contributed significantly to the rate of decay. Revered masterpieces have lost splendor throughout the ages. Indeed, from textual evidence, it is known how artists ia the Renaissance restored works of art from Classical times. These restorers of past centuries attempted to return the object to its original appearance. The fallacy of that idea Hes ia the fact that they could not know the exact original appearance of the work, ie, immediately after its creation therefore, they restored the object according to their subjective opinions. 

The arrest of deterioration and the prevention of its recurrence has higher priority than restoration. Thus, identification of the causes of a problem and the design of measures to stabilize and consoHdate the object are primary considerations. Removal of the symptoms and restoration of the visual appearance comes only after the physical iategrity has beea safeguarded. 

Some of the processes that play a role in the deterioration of particular types of objects are understood (126). The principal techniques employed by conservators to reduce the rates at which these processes take place and, at least partially, undo the damage incurred are mentioned herein. 

Deteriora.tlon. An important source of damage to stone objects is mechanical in nature. Both breakage and abrasion account for much of the losses on objects made of this relatively fragile material. More difficulties are offered by the processes of a chemical nature which play a role in stone deterioration (132—134). 

Stabilization iavolves the removal of the cause of deterioration which is frequentiy soluble salts present ia the stone. If the stmctural strength of the stone permits it, this can be done through soakiag. The object is placed underwater ia a tank, and the water is changed regularly. Another method is by apphcation of poultices on the surface. 

Deterioration. Paintings are composite objects that have high vulnerabiUty. The various materials are adhered to each other, especially in a laminated stmcture, to form a source of potential trouble. Any dimensional change in one of the components or between the components as a consequence of changes in environmental conditions results in a strain on the adhesion of the various parts. Strains can lead to failure of the adhesion. This is one of the principal causes of losses in panel paintings, where the dimensional changes in the wooden support cause losses in adhesion between the paint layer and the support. 

No conservation treatment can completely undo damages to art objects. However, damage can often be prevented (171—173). Many deterioration processes are dependent upon environmental conditions. 

Biodeterioration. For objects made out of organic materials, mold and insect attack are a principal cause of damage. Microbiological organisms can also be responsible for serious deterioration of outdoor stone. Museums, especially storage areas, are quite conducive to providing the conditions in which infestations can occur. Objects are stored in close proximity, and left untouched for prolonged periods, often with Htde if any ak movement. 

Two other broad areas of food preservation have been studied with the objective of developing predictive models. En2yme inactivation by heat has been subjected to mathematical modeling in a manner similar to microbial inactivation. Chemical deterioration mechanisms have been studied to allow the prediction of shelf life, particularly the shelf life of foods susceptible to nonen2ymatic browning and Hpid oxidation. 

The objectives for quality control should relate to the standards you wish to maintain or to prevent from deteriorating. At the corporate level these objectives will address strategic issues such as safety and reliability or customer care. Although you will be striving... 

Improving performance is the objective of measurement. Thus measures should be capable of analysis to help identify where there may be weaknesses that can be corrected. For example, injury data may be published division by division. If one division has deteriorating performance, it will be important to find out whether the deterioration is common across the whole division or specific to one location. 

An important consideration is the effect of filler and its degree of interaction with the polymer matrix. Under strain, a weak bond at the binder-filler interface often leads to dewetting of the binder from the solid particles to formation of voids and deterioration of mechanical properties. The primary objective is, therefore, to enhance the particle-matrix interaction or increase debond fracture energy. A most desirable property is a narrow gap between the maximum (e ) and ultimate elongation ch) on the stress-strain curve. The ratio, e , eh, may be considered as the interface efficiency, a ratio of unity implying perfect efficiency at the interfacial Junction. 

It is desirable for the record to have an objective statement of the nature and degree of color deterioration. The simplest, but least desirable, method is comparison of sample color with color charts or plates such as those used in the Munsell system, Ridgeway s color standards, or the Maerz and Paul dictionary of color. Such a method is limited in value because of the difficulty of obtaining true color matches, and because of variations due to human error. The use of color charts or plates may be much improved in the Munsell system by employing a disk colorimeter (29). Kramer and Smith (21) have pointed out that the results obtained in its application to foods are sometimes difficult to explain and compare, and that the method requires special training of the operator and is tedious and cumbersome. 

Dementia is the loss of function in multiple cognitive domains that occurs over a longer period of time, usually months to years. Diagnostic features include memory impairment and at least one of the following aphasia (deterioration of speech), apraxia (impaired ability to execute motor activities despite intact motor abilities, sensory function, and comprehension of the required task), agnosia (failure to recognize or identify objects despite intact sensory function), or disturbances in executive functioning.1... 

Thus, the way the algorithm works is to set an initial value for the control parameter. At this setting of the control parameter, a series of random moves are made. Equation 3.11 dictates whether an individual move is accepted or rejected. The control parameter (annealing temperature) is lowered and a new series of random moves is made, and so on. As the control parameter (annealing temperature) is lowered, the probability of accepting deterioration in the objective function, as dictated by Equation 3.11, decreases. In this way, the acceptability for the search to move uphill in a minimization or downhill during maximization is gradually withdrawn. 

Various search strategies can be used to locate the optimum. Indirect search strategies do not use information on gradients, whereas direct search strategies require this information. These methods always seek to improve the objective function in each step in a search. On the other hand, stochastic search methods, such as simulated annealing and genetic algorithms, allow some deterioration... 

Most ancient wooden objects recovered in archaeological excavations are usually in a decayed, weak, and friable condition that requires stabilization before the objects can be safely handled and studied. Stabilization of wood and decayed wooden objects, generally includes the use of consolidants, liquid solutions of a resin that impregnates and fills gaps in the wood and on drying solidifies, strengthening its fragile, deteriorated structure (Thompson 1991 Rowell and Barbour 1990). 

Acid rain harms the environment in a number of ways it dissolves many rocks and metals, alters the composition of soils, groundwaters, and lakes, and alters the environmental conditions of living organisms. Acid rain is also particularly harmful to ancient objects and structures, as it plays an important role in their deterioration and sometimes total destruction. Unprotected limestone, marble, and sandstone, all of them widely used in ancient times for building and making statuary, are disintegrated by acid rain, which... 

The atmosphere is a reservoir of aggressive air pollutants that may cause serious deterioration to archaeological objects some of the most active pollutants are sulfur dioxide, hydrogen sulfide, and ozone. 

Stambolov, T. (1969), Manufacture, Deterioration and Preservation of Leather A Literature Survey, ICOM Plenary Meeting, Central Research Laboratory for Objects of Art and Science, Amsterdam. 

Feller, R. L., "Control of Deteriorating Effects of Light on Museum Objects", Museum. 1964, 17, 57-98. 

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