Cluster analysis as a tool in the classification of structures for safety differentiation

1988 ◽  
Vol 15 (4) ◽  
pp. 601-608
Author(s):  
Carlos Ferregut
Keyword(s):  
Cluster Analysis ◽  
Highway Bridges ◽  
Structural Type ◽  
Limit States ◽  
Safety Level ◽  
Code Calibration ◽  
New Concepts ◽  
Safety Parameters ◽  
The Difference ◽  
Selection Of

Different structures and different structural members should reasonably be assigned different levels of reliability to obtain optimum structural performance. This differential assignment of reliabilities or safety parameters is called "safety level differentiation." Up to the present, no simple practical rationale is available for the selection of safety levels. This paper presents a methodology for the selection of safety levels. Cluster analysis is suggested as a tool in the calibration of limit states design codes. The technique may be used to develop importance factors for the design loadings and resistances, reflecting the difference in consequences of failure. The cluster analysis serves to classify a structure according to various attributes that together reflect its social and economic importance. For code specification purposes, it is fundamental to identify which structures in a set are similar, because it facilitates the specification of a single set of code parameters for each structural type, and permits a more rational selection of importance factors. The acceptable number of structural types and the effect of weighing the attributes are also discussed. Some of the new concepts are illustrated using a sample of highway bridges in southwestern Ontario. Key words: safety differentiation, reliability, cluster analysis, code calibration, bridge classification.

Practical code calibration procedures

1979 ◽  
Vol 6 (1) ◽  
pp. 112-119 ◽  
Author(s):  
Andrzej S. Nowak ◽  
Niels C. Lind
Keyword(s):  
Probability Distributions ◽  
Design Standards ◽  
Limit States ◽  
Safety Level ◽  
Performance Factors ◽  
Code Calibration ◽  
Earthquake Load ◽  
Load Effects ◽  
Safety Indices ◽  
Selection Of

The paper deals with a procedure that can be used by a design standards committee to determine safety indices for structures and calculate optimum performance factors for limit states design. Six load components are considered: dead, sustained live, transient live, snow, wind, and earthquake load effects. The procedure is based on an approximation of the probability distributions by normal distributions in the design point situated on the failure boundary. The objective in selection of performance factors is closeness to a target safety level expressed in terms of the target safety index. A computer program was developed to be used in calibration. The procedure is illustrated by examples.

The Ontario bridge code—Development and implementation

1984 ◽  
Vol 11 (4) ◽  
pp. 824-832
Author(s):  
R. A. Dorton
Keyword(s):  
Highway Bridges ◽  
Safety Index ◽  
Design Code ◽  
Limit States ◽  
Safety Level ◽  
New Development ◽  
Live Loads ◽  
Index Value ◽  
Correct Understanding ◽  
Short Time

The Ontario Highway Bridge Design Code was first issued in 1979 and has since been used for the design and evaluation of most bridges in Ontario. The code is in metric SI units, written in a limit states format, and calibrated to a target safety index value of 3.5. It has produced bridges with a more consistent safety level and capable of carrying design live loads twice those previously prescribed. Feedback from users was obtained and their concerns considered in formulating the provisions of the seeond edition in 1983. New bridge codes can be written in a short time and implemented most readily within a relatively small jurisdiction having control of all highways, bridges, and vehicles. Communications between the writers and potential users are important throughout the preparation and implementation phases. It is essential that a commentary volume be issued with a code to ensure correct understanding and interpretation of new provisions. Computer programs should be available, incorporating the code technology before the use of a new code becomes mandatory. Future code needs and likely areas of new development are outlined in the paper. Key words: calibration, codes, computer systems, highway bridges, loadings, safety, structures.

Calibration basis for structural glass design

1987 ◽  
Vol 14 (6) ◽  
pp. 788-794
Author(s):  
Niels C. Lind
Keyword(s):  
Reliability Index ◽  
Limit State ◽  
Structural Response ◽  
Economic Cost ◽  
Structural Glass ◽  
Safety Level ◽  
Design Standard ◽  
Code Calibration ◽  
Importance Factor ◽  
Selection Of

A design standard for structural glass in the limit state design format is currently being developed under the auspices of the Canadian General Standards Board. The standard will be calibrated to a target level of reliability expressed in terms of a reliability index. The selection of this reliability level presents some special problems because the loading is dynamic, the structural response is geometrically nonlinear, and the strength is highly dependent on time, size, and loading history. Selection of safety level so as to achieve a social and economic optimum is described. The optimum reliability index is 3.0, corresponding to a lifetime failure probability of 0.0014, when the social and economic cost of failure is between 15 and 70 times the initial cost. Optimal ranges of applicability over cost for a pair of importance factors (0.8 and 1.25) are also determined. Key words: glass, design, standard, code, calibration, reliability, optimization, importance factor.

Reliability assessment in highway bridge design

2002 ◽  
Vol 29 (5) ◽  
pp. 799-805 ◽  
Author(s):  
M S Cheung ◽  
W C Li
Keyword(s):  
Reliability Assessment ◽  
Highway Bridges ◽  
Highway Bridge ◽  
Design Code ◽  
Bridge Design ◽  
Limit States ◽  
Safety Level ◽  
Reliability Design ◽  
Finite Strip Method ◽  
Standard Design

The current practice of highway bridge design in Canada is based on limit states design. Ideally, by means of the properly calibrated load and resistance factors specified in the applicable design code, limit states design will yield a consistent and uniform safety level for all designed bridge structures. Some factors neglected in the standard design procedures, however, may have unexpected effects on the reliability of a particular design. In this case, to follow a design code exactly may still lead to a certain degree of underdesign or overdesign. Therefore, the reliability assessment is recommended for each particular design, and a simulation-based approach for this assessment is proposed in this study. Examples are presented to support the afore-mentioned recommendation.Key words: highway bridges, reliability, design code, simulation, finite strip method.

Cluster Analysis of Antigenic Profiles of Tumors: Selection of Number of Clusters Using Akaike’s Information Criterion

1990 ◽  
Vol 29 (03) ◽  
pp. 200-204 ◽  
Author(s):  
J. A. Koziol
Keyword(s):  
Cluster Analysis ◽  
Basic Problem ◽  
Information Criterion ◽  
Akaike's Information Criterion ◽  
Cell Surface Antigens ◽  
Number Of Clusters ◽  
Akaike’S Information Criterion ◽  
Multinomial Data ◽  
Tumor Types ◽  
Selection Of

AbstractA basic problem of cluster analysis is the determination or selection of the number of clusters evinced in any set of data. We address this issue with multinomial data using Akaike’s information criterion and demonstrate its utility in identifying an appropriate number of clusters of tumor types with similar profiles of cell surface antigens.

COMBINATORIAL POLYNOMIALLY COMPUTABLE CHARACTERISTICS OF SUBSTITUTIONS AND THEIR PROPERTIES

2020 ◽  
Vol 7 (2) ◽  
pp. 34-41
Author(s):  
VLADIMIR NIKONOV ◽  
◽  
ANTON ZOBOV ◽  
Keyword(s):  
Mathematical Expectation ◽  
Point Of View ◽  
Small Range ◽  
Computational Point ◽  
Wide Range ◽  
Bijective Function ◽  
The Difference ◽  
Element Base ◽  
Selection Of

The construction and selection of a suitable bijective function, that is, substitution, is now becoming an important applied task, particularly for building block encryption systems. Many articles have suggested using different approaches to determining the quality of substitution, but most of them are highly computationally complex. The solution of this problem will significantly expand the range of methods for constructing and analyzing scheme in information protection systems. The purpose of research is to find easily measurable characteristics of substitutions, allowing to evaluate their quality, and also measures of the proximity of a particular substitutions to a random one, or its distance from it. For this purpose, several characteristics were proposed in this work: difference and polynomial, and their mathematical expectation was found, as well as variance for the difference characteristic. This allows us to make a conclusion about its quality by comparing the result of calculating the characteristic for a particular substitution with the calculated mathematical expectation. From a computational point of view, the thesises of the article are of exceptional interest due to the simplicity of the algorithm for quantifying the quality of bijective function substitutions. By its nature, the operation of calculating the difference characteristic carries out a simple summation of integer terms in a fixed and small range. Such an operation, both in the modern and in the prospective element base, is embedded in the logic of a wide range of functional elements, especially when implementing computational actions in the optical range, or on other carriers related to the field of nanotechnology.

Using clusterization principles for the selection of repair sections of main oil pipelines based on diagnostic data

2011 ◽  
Vol 8 (1) ◽  
pp. 201-210
Author(s):  
R.M. Bogdanov
Keyword(s):  
Cluster Analysis ◽  
Defect Density ◽  
Density Variation ◽  
Distance Functions ◽  
Oil Pipeline ◽  
Oil Pipelines ◽  
Classification Of Images ◽  
Main Oil Pipeline ◽  
Selection Of

The problem of determining the repair sections of the main oil pipeline is solved, basing on the classification of images using distance functions and the clustering principle, The criteria characterizing the cluster are determined by certain given values, based on a comparison with which the defect is assigned to a given cluster, procedures for the redistribution of defects in cluster zones are provided, and the cluster zones parameters are being changed. Calculations are demonstrating the range of defect density variation depending on pipeline sections and the universal capabilities of linear objects configuration with arbitrary density, provided by cluster analysis.

scholarly journals Age-dependency in mortality of Finnish family caregivers: a nationwide register-based study

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
T M Mikkola ◽  
H Kautiainen ◽  
M Mänty ◽  
M B von Bonsdorff ◽  
T Kröger ◽  
...  
Keyword(s):  
General Population ◽  
Family Caregivers ◽  
Family Caregiver ◽  
Causes Of Death ◽  
Lower Mortality ◽  
All Cause Mortality ◽  
The Difference ◽  
Caregiver Role ◽  
Selection Of

Abstract Purpose Mortality appears to be lower in family caregivers than in the general population. However, there is lack of knowledge whether the difference in mortality between family caregivers and the general population is dependent on age. The purpose of this study was to analyze all-cause mortality in relation to age in family caregivers and to study their cause-specific mortality using data from multiple Finnish national registers. Methods The data included all individuals, who received family caregiver's allowance in Finland in 2012 (n = 42 256, mean age 67 years, 71% women) and a control population matched for age, sex, and municipality of residence (n = 83 618). Information on dates and causes of death between 2012 and 2017 were obtained from the Finnish Causes of Death Register. Flexible parametric survival modeling and competing risk regression adjusted for socioeconomic status were used. Results The total follow-up time was 717 877 person-years. Family caregivers had lower all-cause mortality than the controls over the follow-up (8.1% vs. 11.6%) both among women (hazard ratio [HR]: 0.64, 95% CI: 0.61-0.68) and men (HR: 0.73, 95% CI: 0.70-0.77). Younger adult caregivers had equal or only slightly lower mortality than their controls, but after age 60, the difference increased markedly resulting in over 10% lower mortality in favor of the caregivers in the oldest age groups. Caregivers had lower mortality for all the causes of death studied, namely cardiovascular, cancer, neurological, external, respiratory, gastrointestinal and dementia than the controls. Of these, the lowest was the risk for dementia (subhazard ratio=0.29, 95%CI: 0.25-0.34). Conclusions Older family caregivers have lower mortality than the age-matched controls from the general population while younger caregivers have similar mortality to their peers. This age-dependent advantage in mortality is likely to reflect selection of healthier individuals into the family caregiver role. Key messages The difference in mortality between family caregivers and the age-matched general population varies considerably with age. Advantage in mortality observed in family caregiver studies is likely to reflect the selection of healthier individuals into the caregiver role, which underestimates the adverse effects of caregiving.

scholarly journals A microfluidic device enabling drug resistance analysis of leukemia cells via coupled dielectrophoretic detection and impedimetric counting

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yağmur Demircan Yalçın ◽  
Taylan Berkin Töral ◽  
Sertan Sukas ◽  
Ender Yıldırım ◽  
Özge Zorlu ◽  
...  
Keyword(s):  
Drug Resistance ◽  
K562 Cells ◽  
Leukemia Cells ◽  
Drug Resistant ◽  
Wild Type ◽  
Gene Expressions ◽  
Before And After ◽  
The Difference ◽  
Selection Of ◽  
Resistant Cells

AbstractWe report the development of a lab-on-a-chip system, that facilitates coupled dielectrophoretic detection (DEP-D) and impedimetric counting (IM-C), for investigating drug resistance in K562 and CCRF-CEM leukemia cells without (immuno) labeling. Two IM-C units were placed upstream and downstream of the DEP-D unit for enumeration, respectively, before and after the cells were treated in DEP-D unit, where the difference in cell count gave the total number of trapped cells based on their DEP characteristics. Conductivity of the running buffer was matched the conductivity of cytoplasm of wild type K562 and CCRF-CEM cells. Results showed that DEP responses of drug resistant and wild type K562 cells were statistically discriminative (at p = 0.05 level) at 200 mS/m buffer conductivity and at 8.6 MHz working frequency of DEP-D unit. For CCRF-CEM cells, conductivity and frequency values were 160 mS/m and 6.2 MHz, respectively. Our approach enabled discrimination of resistant cells in a group by setting up a threshold provided by the conductivity of running buffer. Subsequent selection of drug resistant cells can be applied to investigate variations in gene expressions and occurrence of mutations related to drug resistance.

scholarly journals Weightage Effect during Back-Calculation of Rock-Mass Quality from the Installed Tunnel Support in Rock-Mass Rating and Tunneling Quality Index System

2019 ◽  
Vol 9 (10) ◽  
pp. 2065 ◽  
Author(s):  
Jonguk Kim ◽  
Hafeezur Rehman ◽  
Wahid Ali ◽  
Abdul Muntaqim Naji ◽  
Hankyu Yoo
Keyword(s):  
Rock Mass ◽  
Quality Index ◽  
Rock Bolt ◽  
Rock Mass Rating ◽  
Rock Mass Quality ◽  
Back Calculation ◽  
The Difference ◽  
Bolt Spacing ◽  
Q System ◽  
Selection Of

In extensively used empirical rock-mass classification systems, the rock-mass rating (RMR) and tunneling quality index (Q) system, rock-mass quality, and tunnel span are used for the selection of rock bolt length and spacing and shotcrete thickness. In both systems, the rock bolt spacing and shotcrete thickness selection are based on the same principle, which is used for the back-calculation of the rock-mass quality. For back-calculation, there is no criterion for the selection of rock-bolt-spacing-based rock-mass quality weightage and shotcrete thickness along with tunnel-span-based rock-mass quality weightage. To determine this weightage effect during the back-calculation, five weightage cases are selected, explained through example, and applied using published data. In the RMR system, the weightage effect is expressed in terms of the difference between the calculated and back-calculated rock-mass quality in the two versions of RMR. In the Q system, the weightage effect is presented in plots of stress reduction factor versus relative block size. The results show that the weightage effect during back-calculation not only depends on the difference in rock-bolt-spacing-based rock-mass quality and shotcrete along with tunnel-span-based rock-mass quality, but also on their corresponding values.

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