Actual Abrasion Research Articles

Three-dimensional histological specimen preparation for accurate imaging and spatial reconstruction of the middle and inner ear

Purpose This paper presents a highly accurate cross-sectional preparation technique. The research aim was to develop an adequate imaging modality for both soft and bony tissue structures featuring high contrast and high resolution. Therefore, the advancement of an already existing microgrinding procedure was pursued. The central objectives were to preserve spatial relations and to ensure the accurate three-dimensional reconstruction of histological sections.Methods Twelve human temporal bone specimens including middle and inner ear structures were utilized. They were embedded in epoxy resin, then dissected by serial grinding and finally digitalized. The actual abrasion of each grinding slice was measured using a tactile length gauge with an accuracy of one micrometre. The cross-sectional images were aligned with the aid of artificial markers and by applying a feature-based, custom-made auto-registration algorithm. To determine the accuracy of the overall reconstruction procedure, a well-known reference object was used for comparison. To ensure the compatibility of the histological data with conventional clinical image data, the image stacks were finally converted into the DICOM standard.Results The image fusion of data from temporal bone specimens’ and from non-destructive flat-panel-based volume computed tomography confirmed the spatial accuracy achieved by the procedure, as did the evaluation using the reference object.Conclusion This systematic and easy-to-follow preparation technique enables the three-dimensional (3D) histological reconstruction of complex soft and bony tissue structures. It facilitates the creation of detailed and spatially correct 3D anatomical models. Such models are of great benefit for image-based segmentation and planning in the field of computer-assisted surgery as well as in finite element analysis. In the context of human inner ear surgery, three-dimensional histology will improve the experimental evaluation and determination of intra-cochlear trauma after the insertion of an electrode array of a cochlear implant system.

Determining Abrasion Rate of Armourstones Using Physical Modeling Techniques

Estimating the service life of armourstones used in rubble mound breakwaters remains a controversial issue in coastal engineering. Classification systems investigating durability of armourstones in the literature deal with “potential” performances using engineering properties of intact rocks which are determined in dry conditions. However, “actual” performance loss in armourstones is due to the abrasion in a wet environment, which is a function of time and sea wave impact on the rocks. In this study, actual abrasion rates of basaltic armourstones taken from Giresun Port (Eastern Black Sea, Turkey) are determined by using the Slake Durability test apparatus, which is the only suggested ISRM method for measuring abrasion of rocks in wet condition. However, the standard test method was modified so that microscale models of basaltic rocks from different weight classes were exposed to a number of wave attacks with sea water taken from the port. Therefore, actual abrasion rates of armourstones were determined in an ISRM accepted apparatus but with a new and realistic approach.

Considerations on the European Standard EN 14157 Test Methods: Abrasion Resistance of Natural Stones Used for Flooring in Buildings

In Europe, the Wide Wheel abrasion (WWA) test and the Bohme abrasion (BA) test are among the most widely used standard test methods for determining abrasion resistance of natural stones, the former being the reference test method in EN 14157 Standard. However, it is stated in the Annex-A (Informative) of EN 14157 Standard that very limited data are available to provide correlations between these two test methods. To be able to fill this gap, in this study, 25 different natural stones belonging to sedimentary, metamorphic and igneous groups were tested for their abrasion resistance as well as physico-mechanical properties. Also, for a better interpretation of abrasion resistance characteristics of the tested stone materials, relationships between abrasion resistance and physico-mechanical properties were statistically examined. A statistically significant linear correlation (R 2 = 0.85; P value = 0.000) was established between the WWA test and the BA test, which could be used in practice for converting the measured abrasion resistance values from one testing method to another. It was also found that the correlation between these two test methods improved significantly (R 2 = 0.93; P value = 0.001) when relatively high-porosity stone materials (porosity ≥1%) were separately evaluated. Both methods of abrasion resistance employed in the present study showed statistically significant linear correlations with uniaxial compressive strength and Brazilian tensile strength, the former proving to be a more influencing parameter on resistance to abrasion. Also, from the point view of representing actual abrasion mechanism of stone materials in practice, the necessity of simulating multi-directional foot traffic in abrasion testing methods was discussed. In this respect, the reference test method in the EN 14157 Standard was criticized for not fully meeting this requirement. It was also pointed out that the reference method could have some drawbacks when applied to coarse-grained granitic rocks having cleavable minerals such as plagioclase and orthoclase feldspars.

Accuracy of computer-aided geometric 3D reconstruction based on histological serial microgrinding preparation

Purpose: For our research on computer-optimised and automated cochlear implant surgery, we pursue a model-based approach to overcome the limitations of currently available clinical imaging modalities. A serial cross section preparation procedure has been developed and evaluated concerning accuracy to serve for modelling of a digital anatomic atlas to make delicate soft tissue structures available for pre-operative planning. Methods: A special grinding tool was developed allowing the setting of a specific amount of abrasion as equidistant slice thickness was considered a crucial step. Additionally, each actual abrasion was accurately measured and used during three-dimensional reconstruction of the serial cross-sectional images obtained via digital photo documentation after each microgrinding step. A well-known reference object was prepared using this procedure and evaluated in terms of accuracy. Results: Reconstruction of the whole sample was achieved with an error less than 0.4%, and the edge lengths in the direction of abrasion could be reconstructed with an average error of 0.6 ± 0.3 mm; both prove the realisation of equidistant abrasion. Using artificial registration fiducials and a custom-made algorithm for image alignment, parallelism and rectangularity could be preserved with average errors less than 0.4° ± 0.3°. Conclusion: We present a systematic, practicable and reliable method for the geometrically accurate reconstruction of anatomical structures, which is especially suitable for the middle and inner ear anatomy including soft tissue structures. For the first time, the quality of such a reconstruction process has been quantified and successfully proven for its usability.

DEVELOPMENT OF ABRASION ACCELERATING MACHINE OF THE FLOOR FOR REPRODUCING CHANGE OF THE SLIP RESISTANCE FROM ABRASION IN WALKING

The phenomenon rubbed by the heel at the time of walk has effect on change of slip resistance of a floor. The actual abrasion experiment rubbed by the heel was conducted. As a result, the abrasion sample was able to be obtained and change of slip resistance has been grasped. The accelerating abrasion machine of the floor which gives the abrasion load by the phenomenon to rub was developed. With the developed accelerating abrasion machine, change of the slip resistance obtained in the actual abrasion experiment is reproducible.

Hungarian experiences gained with the aggregate abrasion test

Since 1979 the Institute for Transport Sciences /KTI/ in Hungary has dealt with abrasion tests. This testing method is an adaptation of British Standard BS 812:P.3.9:1975. The results obtained are as follows: -The Hungarian testing method is based on oven-dried chippings -The Hungarian method considers the actual chipping volume. -The actual abrasion value can be determined with ±5% accuracy, on 90% probability level from test results on eight samples. -The KTI standard gives limits for the abrasion value.

A REVIEW OF RECENT STUDIES OF ROCKY COAST TRANSFORMATION DUE TO WAVES

This paper reviews Japanese and alien studies during the past decade, of coastal cliff recession and its related phenomena such as (1) wave-cut platform formation and its defor-mation, (2) abrasion platform development and (3) the process of continental shelf formation having erosional origin, and points out basic, important problems involved in these studies from the viewpoint of rock control theory. The review of the cliff erosion studies refers to recent measuring techniques, field investigations and laboratory experiments; it emphasizes (1) usefulness of aerial photo-graphs in collecting precise data of recession and (2) significance of wave tank experi-ments especially in clarifying basic relation involved in the erosional process. In a sum-mary of the studies of wave-cut platform, they are classified into the two: one is the studies discussing the mechanism of horizontal development in the field or laboratory, and the other the process of vertical deformation of platform surface in the field. Concerning the development of actual abrasion platform, the following topics are mentioned: (1) critical water depth for submarine bedrock erosion, (2) rate of abrasion of shallow water bedrocks, and (3) horizontal growth of abrasion platform. The last section of this paper focuses on a model of continental shelf formation, which was framed up by considering a combination of cliff recession and the postglacial transgression.

Recent Advances in Knowledge of Rubber Friction and Tire Wear

Abstract Progress in the last few years in understanding rubber friction and tire wear justifies a survey of developments since a review of the subject in 1958. Work on fundamental of friction and abrasion has mainly evolved from conceptions formed in the earlier investigations; it had, however, not been realized that wear of tires and, indeed, abrasion on certain laboratory machines brings into play gross properties of the tire or testpiece which affect rate of wear just as much as the actual abrasion resistance of the tread compound. This new field of research has led to rationalization of road testing, and has helped to bridge the gap between laboratory and road. A report on these developments is given. Much of the work is concerned with the viscoelastic nature of rubber friction and abrasion, which has come to light through the experimentally established validity of the rate-temperature equivalence principle for these processes. This principle, which holds good for all viscoelastic processes, is briefly described in the next section in order not to interrupt the subsequent argument.

Abrasion-Reinforcement: Methods of Evaluation

Abstract There are basically three methods by which abrasion-reinforcement may be studied (1) conventional laboratory physical property measurement and empirical prediction of reinforcement (2) laboratory abrasion tests for an actual measurement of reinforcement under accelerated conditions and (3) a study of the mechanism of abrasion with a theoretical deduction of the important physical properties relevant to the phenomenon of abrasion. None of the above are without serious difficulties in their execution at the present state of rubber technology. Known reinforcing materials such as fine particle size carbon blacks increase modulus, tensile strength, tear strength and hardness while decreasing breaking elongation. Measurements of these properties can be very helpful in the selection of reinforcing materials but such measurements used alone are not entirely reliable. They must be supplemented however with actual laboratory abrasion measurements. The choice of a laboratory abrasion test that is strongly correlated with service performance is mandatory. Such a laboratory test must be capable of reliably evaluating all rubbers and all types of reinforcing materials without serious ambiguity. Sources of such ambiguity are abrasive contamination, unrealistic severity effects and an altered dependency of abrasion vs conventional physical properties when compared to tire test results. A laboratory abrasion tester, the Pico abrasion machine, is shown to do a much better job at reliably predicting service preformance for a variety of rubber compositions than the other presently used abrasion machines. The earliest serious work in attempting to deduce the mechanism of wear was by Wiegand who decided that discrete particles were removed. Subsequent work by Sohallamach and others using radiotracers agree in principle with the basic concept of Wiegand. Schallamach has demonstrated that during severe wear a wear pattern or set of ridges at right angles to the direction of abrasion develops. From a study of the motion of this system of ridges he has deduced that rubber is removed by a tearing action or some other rupture process from the under side of the ridges. This is accomplished through a bending back of the forward pointing ridges during contact with the abrading surface. Stiehler on the other hand holds that wear occurs on a “molecular” scale due to localized degradation of the surface layer of the rubber with subsequent volatilization of the degraded fragments. The arguments for discrete particle removal seem to be supported by sufficient evidence to discount the “molecular” removal theory. It must be acknowledged however that under mild abrasion conditions the particles removed are microscopic in size. Zapp has shown in a qualitative treatment that, everything else being equal, the lower the dynamic modulus of a rubber formulation the greater the resistance to abrasion. Schallamach has advanced farther than anyone in explaining what factors or mechanical properties govern the resistance to abrasion in his study of the wear of slipping wheels. The wheels which he refers to are solid rubber wheels of small diameter used to carry a load in much the same manner as pneumatic tires. From the intensive study of solid wheels he has shown the following. At constant angle of slip the abrasion of a slipping wheel is proportional to the resilience of the rubber and is also proportional to the stiffness of the wheel. The term stiffness may be thought of as synonymous with dynamic hardness. When, however, abrasion is carried out at constant side force then the abrasion is again directly proportional to the resilience but is inversely proportional to the stiffness. if the composite qualitative picture as outlined above is correct the tearing strength or tearing energy should play an important role. A brief review of the only really quantitative and theoretical work of the tearing of rubber is given. This work has been carried out by Greensmith, Thomas and Mullins at the NRPRA. It can be concluded from their work that no clear cut evidence is on hand that shows that the tear strength of known abrasion resistant formulations is materially greater than for very poor wearing compounds. While there is some evidence indicating that formulations reinforced with HAF do possess higher tear strengths than corresponding gum vulcanizates under some conditions these conditions are not the ones that are present during abrasion. Unfortunately the tear strengths of vulcanizates at high rates of strain have not been determined due to the extreme experimental difficulties involved. Such measurements are needed to determine what role tear strength really plays in the overall abrasion process.

26—A TEST FOR THE ASSESSMENT OF CARPET COMPRESSION DURING WEAR

A machine is described that gives information about the ‘bedding-down’ effect that occurs when a carpet is laid on a floor and before much actual abrasion or loss of fibre takes place. The results are correlated with corridor wearing trials and a discussion is given on some aspects of the effect of carpel construction on loss of thickness during laboraiory tests.

Relationship between Laboratory Abrasion Tests and Service Performance

Abstract In development work on GR-S commercial recapping compounds originated in 1943 by the Directorate of Mechanical Engineering, Department of National Defence, Ottawa, Canada, in which an attempt was made to correlate road performance with physical properties as determined in the laboratory, it was found that no relationship whatever existed between the results of road tests carried out under the supervision of that directorate and standard laboratory abrasion resistance tests carried out in the Canadian National Research Council Rubber Laboratory at Ottawa. In the laboratory test the sandpaper in the abrasion machine became coated with a smear of tacky viscous material which the air jet was unable to remove. Under these conditions the rubber tends to slide over the sandpaper surface, with relatively little actual abrasion of the rubber. The effect remains even after a considerable overcure of the sample. It was felt that the removal of the tacky viscous material from vulcanized GR-S by extraction might give more reliable abrasion resistance results, inasmuch as, on the road, rubber is constantly coming in contact with a new surface and such viscous material is thus being continually removed as it migrates to the surface of the rubber. From this point of view, then, the tread surface while being abraded on the road may be looked upon as extracted rubber and may be considered as conforming closely to the extracted laboratory specimen.

Relationship between Laboratory Abrasion Tests and Service Performance

Abstract In development work on GR-S commercial recapping compounds originated in 1943 by the Directorate of Mechanical Engineering, Department of National Defence, Ottawa, Canada, in which an attempt was made to correlate road performance with physical properties as determined in the laboratory, it was found that no relationship whatever existed between the results of road tests carried out under the supervision of that directorate and standard laboratory abrasion resistance tests carried out in the Canadian National Research Council Rubber Laboratory at Ottawa. In the laboratory test the sandpaper in the abrasion machine became coated with a smear of tacky viscous material which the air jet was unable to remove. Under these conditions the rubber tends to slide over the sandpaper surface, with relatively little actual abrasion of the rubber. The effect remains even after a considerable overcure of the sample. It was felt that the removal of the tacky viscous material from vulcanized GR-S by extraction mi...