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Condition Assessment (condition + assessment)

Distribution by Scientific Domains

Engineering	50%
Life Sciences	40%

Selected Abstracts

Condition Assessment by Visual Inspection for a Bridge Management System

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 2 2005
Vincenzo Gattulli
This article deals with a procedure for bridge condition assessment by visual inspection developed during the planning and preliminary design of the BMS for the public railway networks in Italy. The main modules adopted in the procedure are: bridge inventory, computer-aided visual inspection, automated defect catalog, and priority-ranking procedure. The probabilistic models used to calibrate the condition evaluation algorithm are discussed. Different levels of deficiency have been individuated for each class of bridge structure belonging to the managed stock. The procedure allows comparison and relative ranking of deficiency conditions across different types of bridge structures. The results of a visual inspection campaign conducted for a set of bridges with different structural characteristics are reported and evaluated within the framework of the developed BMS. [source]

Dynamische Zustandsbewertung einer Verbundbrücke: Beobachtung äußerer und nichtlinearer Einflüsse auf die modalen Eigenschaften

BETON- UND STAHLBETONBAU, Issue 8 2010
Volker Bungard Dipl.-Ing.
Bauwerksüberwachung; Dynamische Einwirkungen/Erdbeben; Brückenbau; Versuche Abstract Bei der Anwendung dynamischer Untersuchungsmethoden zur Zustandsbewertung von Ingenieurbauwerken aus Stahl- und Spannbeton sowie Verbundbau spielen Veränderungen von Rand- und Umweltbedingungen auf die modalen Parameter eine wesentliche Rolle. Während man diese im Laborexperiment weitest gehend überwachen bzw. ausschließen kann, sind sie bei in-situ Versuchen nur schwer zu kontrollieren. Am Beispiel einer Verbundbrücke soll demonstriert werden, welche Größenordnung die Veränderung von Randbedingungen (z. B. Veränderung von anregenden Kräften) und Umwelteinflüsse (z. B. Temperatur) auf die dynamischen Parameter einer in-situ Struktur haben können. Die Größenordnung dieser Veränderungen wird mit Veränderungen, die aus wirklichen Strukturschäden resultieren können, verglichen und bewertet. Dynamic Condition Assessment of a Composite Bridge: Investigation of External and Nonlinear Influences on the Modal Properties Using dynamic investigation methods to assess the state of civil constructions like reinforced and prestressed concrete structures as well as composite structures, changes in boundary conditions and environmental influences play a decisive role. Under laboratory conditions it is possible to control respectively to exclude these influences but it is not always possible to control and to exclude them when testing in-situ. By means of dynamic measurements which are conducted on a composite bridge, possible changes in dynamic properties resulting from changes in the amplitude of the excitation force and resulting from changes in the temperature conditions are demonstrated. The dimension of these changes is compared with changes in modal properties resulting from real structural defects and structural damages. [source]

Condition Assessment by Visual Inspection for a Bridge Management System

Towards a national approach to vegetation condition assessment that meets government investors' needs: A policy perspective

ECOLOGICAL MANAGEMENT & RESTORATION, Issue 2006
David Parkes
No abstract is available for this article. [source]

An improved perturbation method for stochastic finite element model updating

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 13 2008
X. G. Hua
Abstract In this paper, an improved perturbation method is developed for the statistical identification of structural parameters by using the measured modal parameters with randomness. On the basis of the first-order perturbation method and sensitivity-based finite element (FE) model updating, two recursive systems of equations are derived for estimating the first two moments of random structural parameters from the statistics of the measured modal parameters. Regularization technique is introduced to alleviate the ill-conditioning in solving the equations. The numerical studies of stochastic FE model updating of a truss bridge are presented to verify the improved perturbation method under three different types of uncertainties, namely natural randomness, measurement noise, and the combination of the two. The results obtained using the perturbation method are in good agreement with, although less accurate than, those obtained using the Monte Carlo simulation (MCS) method. It is also revealed that neglecting the correlation of the measured modal parameters may result in an unreliable estimation of the covariance matrix of updating parameters. The statistically updated FE model enables structural design and analysis, damage detection, condition assessment, and evaluation in the framework of probability and statistics. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Forage production and plant diversity in two managed rangelands in the Main Ethiopian Rift

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2010
Ali Seid Mohammed
Abstract The purpose of this study was to investigate the floristic diversity and productivity of managed rangelands in the Main Ethiopian Rift (MER). The relationships between forage production and plant diversity among four native range sites (i.e. Alagae hay-field, Alagae woodland, Neteli hay-field and Neteli woodland) that were different in range condition were examined. The major variables studied include floristic diversity, herbaceous biomass production and range condition assessment. A total of 213 species, representing 143 genera and 40 families, were identified from the study sites. The range conditions ranked from poor to good. Herbaceous biomass production followed a quadratic relationship with range condition. The humpback model was tested and found to be applicable to the MER rangelands. The study results reflect on the need for optimizing productivity and biodiversity conservation and put emphasis on the need for integrating agricultural production and biodiversity conservation interests for the sustainable utilization of rangelands. Résumé L'objectif de cette étude était d'étudier la diversité floristique et la productivité de pâturages gérés dans le Rift éthiopien principal (REP). La relation entre la production de fourrage et la diversité de plantes dans quatre sites indigènes dont les conditions étaient différentes (à savoir : prairie à faucher d'Alagae, forêt d'Alagae, prairie de Neteli et forêt de Neteli) ont été examinées. Les principales variables étudiées comprennent la diversité floristique, la production de biomasse herbacée et l'évaluation des conditions de la région. Un total de 213 espèces appartenant à 143 genres et à 40 familles ont été identifiées sur les sites de l'étude. Les conditions de la région variaient de médiocre à bonne. La production de biomasse herbacée suivait une relation quadratique avec les conditions de la région. Le modèle « épaulard » (Humpback model) a été testé et l'on a trouvé qu'il pouvait s'appliquer aux pâturages REP. Les résultats de l'étude se reflètent dans le besoin d'optimiser la productivité et la conservation de la biodiversité, et mettent l'accent sur la nécessité d'intégrer les intérêts de la production agricole et de la conservation de la biodiversité pour arriver à une utilisation durable des pâturages. [source]

Establishing survey and monitoring protocols for the assessment of conservation status of fish populations in river Special Areas of Conservation in the UK

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2009
I.G. Cowx
Abstract 1.Under the EC Habitats Directive (92/43/EEC), several rivers in the UK have been designated Special Areas of Conservation (SACs) because they support important populations of fish species. Several factors need to be considered when establishing survey protocols to assess the conservation status of fish species in these rivers. 2.It is important to understand the biology and habitat requirements of fish species and to design appropriate monitoring surveys that adequately assess the status of the fish populations. This information can, in turn, provide the basis for establishing sustainable conservation targets for specific stocks, a process known as condition assessment. 3.Favourable condition of fish species in SAC rivers is assessed using three criteria. The first relates to density of fish in various life stages against pre-set targets, assuming that an appropriate number of sites is surveyed to account for natural spatial and temporal variations in fish populations. The second is evaluation of the demographic structure to demonstrate continued recruitment success. Third, by mapping the distribution of the target species in individual rivers and where favourable condition is only achieved where there has been no reduction in the distribution range river between surveys. 4.The framework described was developed from limited survey data. As more monitoring and assessment data become available, the threshold criteria for favourable condition for each species should be improved, and uncertainty in the procedures reduced. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Überwachung und Analyse der Lebensdauer von Tunnelbauwerken

BETON- UND STAHLBETONBAU, Issue 1 2007
Konrad Bergmeister Prof. Dipl.-Ing.
Im Tunnelbau bildet die Überwachung der signifikanten Einwirkungs- und Strukturparameter während der Bauphase und des Betriebs die Basis für die Bewertung des Zustands und der Sicherheit des Bauwerks. Die erfassten Daten stellen des Weiteren die Grundlage zur nummerischen und mechanischen Modellbildung dar, um eine effiziente Entscheidungsfindung und Maßnahmenplanung zu gewährleisten. Die Überwachung beinhaltet die Erfassung und Bewertung der geologischen Gegebenheiten, der induzierten Auswirkungen während des Vortriebs und die kontinuierliche Kontrolle für den weiteren Betrieb und Unterhalt des Bauwerks. Methoden der Bauwerksüberwachung und Diagnose stellen aufgrund der quantitativ erfassten Systemparameter ein wesentliches Element für die Zuverlässigkeitsanalyse dar. Die geeignete Wahl von Kontroll- und Messinstrumenten ist jedoch nur einen Teilaspekt der Bauwerksüberwachung. Die Auswertung und Interpretation der erhobenen Daten, die Gegenüberstellung mit den normativen Anforderungen und Grenzwerten, die Anpassung der analytischen Modellannahmen aufgrund des Vergleichs von gemessenen und berechneten Daten zeigen die Komplexität dieses Aufgabengebietes. Monitoring and Analysis of Durability of Tunnels Monitoring continuously the decisive parameters, during both the construction and the operation phase, provides the quantitative basis for safety and condition assessment, analytical modelling and decision making. This includes evaluating the conditions and induced effects during excavation and construction, and continues during operation in terms of maintenance decision making and reliability assessment. The utilisation of monitoring devices and measurement elements is however only the start of monitoring field performance. Interpretation of the acquired data is equally important, namely the validation of compliance with normative specifications and the comparison of measured and calculated data in order to evaluate analytical model assumptions. [source]

Influence of stream geomorphic condition on fish communities in Vermont, U.S.A.

FRESHWATER BIOLOGY, Issue 10 2006
EIKA P. SULLIVAN, S. MA
Summary 1. Evaluations of stream geomorphic condition may increase our understanding of the composite effects of human-induced habitat change on fish communities. Using systematic sampling of 44 reaches spread across 26 rivers in Vermont from 2002 through 2004, we tested the hypothesis that stream reaches in reference geomorphic condition would support fish assemblages that differed in diversity and productivity from fish communities found in reaches of poorer geomorphic condition. 2. At each study reach, we sampled the fish community, identified the morphological unit according to common stream classification systems and then evaluated the extent of deviation from reference geomorphic condition using a regionally adapted geomorphic assessment methodology. 3. We used principal component analysis (PCA) and linear regression to build exploratory models linking stream geomorphic condition to fish community characteristics. 4. Our results suggest that geomorphic condition significantly influences fish community diversity, productivity and condition. Geomorphic condition was a significant factor in all of our fish community models. In conjunction with additional reach characteristics, geomorphic condition explained up to 31% of the total variance observed in models for species diversity of fish communities, 44% of the variance in assemblage biomass and 45% of the variance in a regional index of biotic integrity. 5. Our work builds on single-species evidence that geomorphic characteristics represent important local-scale fish-habitat variables, showing that stream geomorphic condition is a dominant factor affecting entire fish communities. Our results enhance our understanding of the hierarchy of factors that influences fish community diversity and organisation and support the use of geomorphic condition assessments in stream management. [source]

Coat condition, housing condition and measurement of faecal cortisol metabolites , a non-invasive study about alopecia in captive rhesus macaques (Macaca mulatta)

JOURNAL OF MEDICAL PRIMATOLOGY, Issue 1 2006
Hanspeter W. Steinmetz
Abstract Background, Previous studies have characterized alopecia in captive rhesus macaques (Macaca mulatta) by a mixed partial to complete alopecia in a bilateral symmetric pattern. Methods, In this study, coat condition assessments were related to exogenous and endogenous factors in captive rhesus macaques under different housing conditions in order to identify disturbances in environmental factors controlling or influencing hair growth. Additionally, the degree of alopecia was investigated in relation to adrenal endocrine function as an indicator of social stress using faecal glucocorticoid measurements. Results, Hair loss was found to vary with season and sex, was most pronounced in adult females during the winter and spring months. Generally, infants were not affected, but alopecia developed during adolescence. However, the housing system, available enclosure space and variations in group size and composition also appeared to influence coat condition. Levels of immunoreactive cortisol metabolites (11-oxoetiocholanolone) in faeces were significantly negatively correlated with alopecia, suggesting a relationship between hypothalamic-pituitary-adrenal (HPA) axis activity and hair loss in captive rhesus macaques. Conclusions, Although the present study demonstrates the influence of the HPA axis on coat condition, it is not known if hair loss is caused by abnormal behaviour or hormonal imbalances of the HPA axis itself. Our data suggest that alopecia in rhesus macaques is a highly complex multicausal disorder. [source]