Undamaged Test Research Articles

Development of welding discontinuity identification system using statistical texture feature extraction and ANN classification on digital radiographic image

Discontinuity in welds is one of the causes of the quality of a connection in the material decreases function. Undamaged test with radiographic method is one of the tests to see the quality of a weld. The test results are radiograph images and evaluated by a radiographer. So this research is designed by optimizing a system to help the work of a radiography expert in identifying discontinuities by utilizing the Matlab Application. On this system uses the method of characteristic extraction and classification of neural networks (AAN). The system uses a characteristic extraction method with geometric invariant moment (GIM) algorithms and a gray level co-occurenece matrix (GLCM) as identification values used in the classification process. The calcification process uses a backpropagation-type multilayer Artificial Neural Network. The types of discontinuities used as data in this system are incompleted of penetration, crack, wormhole, and distributed porosity using a total of 800 datasets of radiograph imagery data. This data sharing is organized using k fold cross validation. The study conducted 15 experiments in system testing to prove the truth in identifying. The results of the experiment resulted in the highest average performance score reaching 93.33%

Micromechanical properties of wood cell wall and interface compound middle lamella using quasi-static nanoindentation and dynamic modulus mapping

Micromechanical properties of individual phases within wood tissues are crucially important for the processing and utilization of this biomass material. The quasi-static nanoindentation and dynamic modulus mapping techniques were employed to study the micromechanical properties of wood cell walls and their interface regions. Nanoindentation results showed that the reduced modulus of secondary cell walls (18 GPa) was twice that of interface compound middle lamella (CML) (7 GPa). Modulus mapping, with advantages of high resolution and undamaged test over conventional nanoindentation, was able to analyse the subtle variations in micromechanical properties of individual phases within the whole wood tissues, especially interface layers. The variation tendency across adjacent cell walls was similar to that tested by nanoindentation, and the secondary cell walls exhibited maxima in the middle of the secondary wall and slightly reduction approaching to the S1 and S3 layers. Moreover, the storage modulus of interface region CML showed “W” distribution, which meant that the modulus first fell and then rose from the central area to edge regions.

Detrimental and Neutral Effects of a Wild Grass-Fungal Endophyte Symbiotum on Insect Preference and Performance

Seed-borne Epichloë/Neotyphodium Glenn, Bacon, Hanlin (Ascomycota: Hypocreales: Clavicipitaceae) fungal endophytes in temperate grasses can provide protection against insect attack with the degree of host resistance related to the grass—endophyte symbiotum and the insect species involved in an interaction. Few experimental studies with wild grass—endophyte symbiota, compared to endophyte-infected agricultural grasses, have tested for anti-insect benefits, let alone for resistance against more than one insect species. This study quantified the preference and performance of the bird cherry oat-aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae) and the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), two important pests of forage and cereal grasses, on Neotyphodium-infected (E+) and uninfected (E-) plants of the wild grass Alpine timothy, Phleum alpinum L. (Poales: Poaceae). The experiments tested for both constitutive and wound-induced resistance in E+ plants to characterize possible plasticity of defense responses by a wild E+ grass. The aphid, R. padi preferred E- over E+ test plants in choice experiments and E+ undamaged test plants constitutively expressed antibiosis resistance to this aphid by suppressing population growth. Prior damage of E+ test plants did not induce higher levels of resistance to R. padi. By contrast, the beetle, O. melanopus showed no preference for E+ or E- test plants and endophyte infection did not adversely affect the survival and development of larvae. These results extend the phenomenon of variable effects of E+ wild grasses on the preference and performance of phytophagous insects. The wild grass— Neotyphodium symbiotum in this study broadens the number of wild E+ grasses available for expanded explorations into the effects of endophyte metabolites on insect herbivory.

Analysis of reinforced concrete beams with corrosion damaged stirrups for shear capacity

Corrosion of embedded carbon steel is a leading factor in deterioration of ageing conventional reinforced concrete structures. Methods to accurately predict remaining capacity of corrosion damaged elements, especially shear capacity, are lacking. In this paper, ACI-AASHTO approach, strut and tie method, modified compression field theory, and Response 2000™ were used to predict the shear strength of corrosion damaged and undamaged test beams. The methods were modified to account for the corrosion induced damage to both the concrete section and stirrups. Each of the methods considered, with the proposed modifications, reasonably estimated the remaining shear capacity of large-size laboratory specimens subjected to accelerated corrosion of embedded stirrups.

Bayesian probabilistic damage detection of a reinforced-concrete bridge column

A Bayesian probabilistic approach for damage detection has been proposed for the continuous monitoring of civil structures (Sohn H, Law KH. Bayesian probabilistic approach for structure damage detection. Earthquake Engineering and Structural Dynamics 1997; 26:1259–1281). This paper describes the application of the Bayesian approach to predict the location of plastic hinge deformation using the experimental data obtained from the vibration tests of a reinforced-concrete bridge column. The column was statically pushed incrementally with lateral displacements until a plastic hinge is fully formed at the bottom portion of the column. Vibration tests were performed at different damage stages. The proposed damage detection method was able to locate the damaged region using a simplified analytical model and the modal parameters estimated from the vibration tests, although (1) only the first bending and first torsional modes were estimated from the experimental test data, (2) the locations where the accelerations were measured did not coincide with the degrees of freedom of the analytical model, and (3) there existed discrepancies between the undamaged test structure and the analytical model. The Bayesian framework was able to systematically update the damage probabilities when new test data became available. Better diagnosis was obtained by employing multiple data sets than just by using each test data set separately. Copyright © 2000 John Wiley & Sons, Ltd.

Progression of approximal caries in relation to iatrogenic preparation damage.

The aim of the present study was to evaluate the effect of iatrogenic preparation damage on the need for operative caries treatment of approximal surfaces, adjacent to Class II amalgam restorations. The material was collected by 77 dentists from the Public Dental Child Health Service in Denmark. It consisted of die-stone models of 187 first-time Class II preparations, adjacent to 190 unfilled approximal surfaces of 58 primary and 132 permanent teeth. The cavity preparations were performed in children between 4 and 17 years of age. They were all filled with amalgam. Information about operative treatment and exfoliation or extraction of the preparation teeth and the adjacent teeth during the following seven years was obtained from the patients' records. Stereomicroscopic examination of the models revealed preparation damage on 64% of the unfilled approximal surfaces in primary teeth and on 69% of the corresponding test surfaces in permanent teeth. During the observation period, operative treatment was performed on 10% of the undamaged test surfaces in primary teeth and on 35% of the damaged ones (p less than 0.05). The corresponding figures for test surfaces in permanent teeth were 6% and 15% (p less than 0.05). It is concluded that iatrogenic preparation damage is a frequent side-effect of operative intervention with approximal caries lesions, and represents a dental health problem, since the damage increases caries progression and the perceived need for restorative therapy of the adjacent teeth.

Chemical properties of the test of ascidians in relation to predation

The undamaged test of a range of aplousobranch ascidian species is shown to be chemically neutral. Acid is generated by surface test cells following cell lysis and is rapidly neutralised in the presence of calcareous test inclusions and/or sea water. Neither the capacity to produce acid nor the presence of vanadium prevents predation on ascidian species in the field.

Test Bullet Recovery

A discussion of means used to recover an undamaged test bullet for comparison to an evidence bullet.

Differential Response to Hail Damage among Pima Cotton Strains1

Large differences in vegetative regrowth among nine cultivars were noted in an American Pima cotton (Gossypium barbadense L.) regional test after severe hail damage on 22 July 1974. These differences were correlated negatively with the lint yield of the same cultivars in a nearby, undamaged, Pima cotton regional test. Correlations of number of new leaves and dry weight of new leaves 5 weeks after hail with lint yield on the undamaged test were −0.84 and −0.91, respectively. Theories on transport and utilization of photosynthate in cotton were used to explain differences in recovery among cultivars.