Standard Guide for General Reliability

2018 ◽  
Author(s):  
Keyword(s):  
General Reliability

Benefits from Computerized Adaptive Testing as Seen in Simulation Studies

1999 ◽  
Vol 15 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Lutz F. Hornke
Keyword(s):  
Measurement Error ◽  
Computerized Adaptive Testing ◽  
Test Procedure ◽  
Adaptive Testing ◽  
Parameter Estimates ◽  
Simulation Studies ◽  
Computerized Adaptive Test ◽  
Item Banks ◽  
Item Parameters ◽  
General Reliability

Summary: Item parameters for several hundreds of items were estimated based on empirical data from several thousands of subjects. The logistic one-parameter (1PL) and two-parameter (2PL) model estimates were evaluated. However, model fit showed that only a subset of items complied sufficiently, so that the remaining ones were assembled in well-fitting item banks. In several simulation studies 5000 simulated responses were generated in accordance with a computerized adaptive test procedure along with person parameters. A general reliability of .80 or a standard error of measurement of .44 was used as a stopping rule to end CAT testing. We also recorded how often each item was used by all simulees. Person-parameter estimates based on CAT correlated higher than .90 with true values simulated. For all 1PL fitting item banks most simulees used more than 20 items but less than 30 items to reach the pre-set level of measurement error. However, testing based on item banks that complied to the 2PL revealed that, on average, only 10 items were sufficient to end testing at the same measurement error level. Both clearly demonstrate the precision and economy of computerized adaptive testing. Empirical evaluations from everyday uses will show whether these trends will hold up in practice. If so, CAT will become possible and reasonable with some 150 well-calibrated 2PL items.

Reliability Concepts in Reservoir Design

1989 ◽  
Vol 20 (4-5) ◽  
pp. 231-248 ◽  
Author(s):  
Erich J. Plate
Keyword(s):  
Water Resources ◽  
Reliability Analysis ◽  
Conceptual Models ◽  
Dam Failure ◽  
Figures Of Merit ◽  
Irrigation Reservoir ◽  
Modes Of Failure ◽  
Reservoir Design ◽  
General Reliability ◽  
Operational Failure

The case of a dam for an irrigation reservoir is used as an example to illustrate the different modes of failure of a water resources system. The types of failure to which a dam can be subjected are described in the first section of the paper, in terms of a framework of general reliability analysis. Two applications are considered: the case of operational failure, illustrated by means of an irrigation reservoir for arid countries, and the case of dam failure due to overtopping. Conceptual models are given which permit the inclusion of reliability and other figures of merit into both operation and safety analysis.

scholarly journals In Vitro Newly Isolated Environmental Phage Activity against Biofilms Preformed by Pseudomonas aeruginosa from Patients with Cystic Fibrosis

2021 ◽  
Vol 9 (3) ◽  
pp. 478
Author(s):  
Ersilia Vita Fiscarelli ◽  
Martina Rossitto ◽  
Paola Rosati ◽  
Nour Essa ◽  
Valentina Crocetta ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Multidrug Resistant ◽  
In Vitro Test ◽  
Chronic Infections ◽  
Hospital Environments ◽  
Vitro Test ◽  
General Reliability ◽  
Phage Activity

As disease worsens in patients with cystic fibrosis (CF), Pseudomonas aeruginosa (PA) colonizes the lungs, causing pulmonary failure and mortality. Progressively, PA forms typical biofilms, and antibiotic treatments determine multidrug-resistant (MDR) PA strains. To advance new therapies against MDR PA, research has reappraised bacteriophages (phages), viruses naturally infecting bacteria. Because few in vitro studies have tested phages on CF PA biofilms, general reliability remains unclear. This study aimed to test in vitro newly isolated environmental phage activity against PA isolates from patients with CF at Bambino Gesù Children’s Hospital (OBG), Rome, Italy. After testing in vitro phage activities, we combined phages with amikacin, meropenem, and tobramycin against CF PA pre-formed biofilms. We also investigated new emerging morphotypes and bacterial regrowth. We obtained 22 newly isolated phages from various environments, including OBG. In about 94% of 32 CF PA isolates tested, these phages showed in vitro PA lysis. Despite poor efficacy against chronic CF PA, five selected-lytic-phages (Φ4_ZP1, Φ9_ZP2, Φ14_OBG, Φ17_OBG, and Φ19_OBG) showed wide host activity. The Φ4_ZP1-meropenem and Φ14_OBG-tobramycin combinations significantly reduced CF PA biofilms (p < 0.001). To advance potential combined phage-antibiotic therapy, we envisage further in vitro test combinations with newly isolated phages, including those from hospital environments, against CF PA biofilms from early and chronic infections.

A New Numerical Method for General Failure Probability with Fuzzy Failure Region

2007 ◽  
Vol 353-358 ◽  
pp. 997-1000 ◽  
Author(s):  
Lei Chen ◽  
Zhen Zhou Lu
Keyword(s):  
Numerical Method ◽  
Failure Probability ◽  
High Efficiency ◽  
Joint Probability ◽  
Line Sampling ◽  
Failure Region ◽  
Random Failure ◽  
Total Integral ◽  
Variable Space ◽  
General Reliability

For general reliability analysis with fuzzy failure region F % , the general failure probability F P% is defined as the integral of product of μF% [g( y)] , the membership of performance function ( ) g y to F % , and joint Probability Density Function (PDF) f ( y) over , the total variable space, i.e. [ ( )] ( ) F F P μ g f d % = ∫ ∫ % y y y L . On the basis of line sampling, an efficient method for random failure probability analysis with clear failure region, a new numerical method is presented to calculate F P% . In the presented method, the total integral region is split into m clear sub-regions i F in a way that the value of g( y) in i F can be approximately viewed as i g , a constant independent of y , and the value of [ ( )] F μ % g y in i F can be viewed as a constant ( ) F i μ g % subsequently. Due to the closely invariant property of [ ( )] F μ g % x in i F and 1 2 m = F I F ILI F , F P% is transformed into the sum of ( ) F i μ g % ( ) i F ∫L∫ f y dy , where ( ) i F ∫L∫ f y dy is the random failure probability with the clear failure region i F and can be obtained by line sampling. The high efficiency of the presented method resulted from that of the line sampling is demonstrated by the illustration.

scholarly journals Diagnostics of supercapacitors

2018 ◽  
Vol 182 ◽  
pp. 01009 ◽  
Author(s):  
Valeriy Martynyuk ◽  
Oleksander Eromenko ◽  
Juliy Boiko ◽  
Tomasz Kałaczyński
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Methodological Approach ◽  
Frequency Dispersion ◽  
Technical Condition ◽  
Transient Processes ◽  
Nonlinear Frequency ◽  
Diagnostic Reliability ◽  
General Reliability ◽  
The Mathematical Model

The paper represents the mathematical model for diagnostics of supercapacitors. The research objectives are the problem of determining a supercapacitor technical condition during its operation. The general reliability of diagnostics is described as the methodological and instrumental reliabilities of diagnostics. The instrumental diagnostic reliability of supercapacitor includes the probabilities of errors of the first and second kind, α and β respectively. The methodological approach to increasing the reliability of supercapacitor diagnostic has been proposed, in terms of multi-parameter supercapacitor diagnostic by applying nonlinear, frequency dependent mathematical models of supercapacitors that take into account nonlinearity, frequency dispersion of parameters and the effect of transient processes in supercapacitors. The more frequencies, operating voltages and currents are applied in the supercapacitor diagnostics, the more methodological reliability of diagnostics will increase in relation to the methodological reliability of supercapacitor diagnostics when only one frequency, voltage and current are applied.

scholarly journals Validation of nitric acid retrieved by the IMK-IAA processor from MIPAS/ENVISAT measurements

2007 ◽  
Vol 7 (3) ◽  
pp. 721-738 ◽  
Author(s):  
D. Y. Wang ◽  
M. Höpfner ◽  
G. Mengistu Tsidu ◽  
G. P. Stiller ◽  
T. von Clarmann ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Michelson Interferometer ◽  
Infrared Emission ◽  
Data Sets ◽  
Data Processor ◽  
Infrared Spectrometer ◽  
Non Local ◽  
General Reliability ◽  
Mean Differences ◽  
Horizontal Inhomogeneity

Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the ENVISAT satellite provides profiles of temperature and various trace-gases from limb-viewing mid-infrared emission measurements. The stratospheric nitric acid (HNO3) from September 2002 to March 2004 was retrieved from the MIPAS observations using the science-oriented data processor developed at the Institut für Meteorologie und Klimaforschung (IMK), which is complemented by the component of non-local thermodynamic equilibrium (non-LTE) treatment from the Instituto de Astrofísica de Andalucía (IAA). The IMK-IAA research product, different from the ESA operational product, is validated in this paper by comparison with a number of reference data sets. Individual HNO3 profiles of the IMK-IAA MIPAS show good agreement with those of the balloon-borne version of MIPAS (MIPAS-B) and the infrared spectrometer MkIV, with small differences of less than 0.5 ppbv throughout the entire altitude range up to about 38 km, and below 0.2 ppbv above 30 km. However, the degree of consistency is largely affected by their temporal and spatial coincidence, and differences of 1 to 2 ppbv may be observed between 22 and 26 km at high latitudes near the vortex boundary, due to large horizontal inhomogeneity of HNO3. Statistical comparisons of MIPAS IMK-IAA HNO3 VMRs with respect to those of satellite measurements of Odin/SMR, ILAS-II, ACE-FTS, as well as the MIPAS ESA product show good consistency. The mean differences are generally ±0.5 ppbv and standard deviations of the differences are of 0.5 to 1.5 ppbv. The maximum differences are 2.0 ppbv around 20 to 25 km. This gives confidence in the general reliability of MIPAS HNO3 VMR data and the other three satellite data sets.

Evaluation of Annual Loads of Nutrients and Suspended Solids in Baltic Rivers

2003 ◽  
Vol 34 (3) ◽  
pp. 203-220 ◽  
Author(s):  
Pirkko Kauppila ◽  
Jari Koskiaho
Keyword(s):  
Suspended Solids ◽  
Reliable Method ◽  
Averaging Method ◽  
Correlation Method ◽  
Load Estimation ◽  
Calculation Methods ◽  
Simulation Experiments ◽  
Considerable Uncertainty ◽  
River Types ◽  
General Reliability

Estimation of pollutant fluxes through river systems calls for accurate and precise load estimation. However, considerable uncertainty is associated with these estimates due to diffuse loading, which sets high requirements not only on sampling frequencies but also on calculation methods. The aim was to examine the variation in load calculations and the reliability of the load estimates of total phosphorus, total nitrogen and suspended solids in 24 Baltic rivers varying in size and land-use characteristics. Reliability of the load estimates was tested by simulation experiments in the river Paimionjoki using a Monte Carlo procedure. The estimates calculated by the most reliable method were compared to the loads estimated by five other methods. The general reliability (RMSE) for P and SS was best by the correlation method and for N by the periodic method. Load calculations varied greatly depending both on the characteristics of the rivers and the calculation method. The flow-stratified method overestimated the P and SS loads by about 20% in large low-lake rivers. In small low-lake rivers, the overestimation was 10% and over 14% for P and SS, respectively. By contrast, the averaging method underestimated P and SS loads by 10% and 21% in small agricultural low-lake rivers. All the methods produced rather similar results for N in each of the river types.

Further analysis of surface bond lengths measured for chemisorption on metal surfaces

1986 ◽  
Vol 64 (7) ◽  
pp. 1385-1389 ◽  
Author(s):  
K. A. R. Mitchell ◽  
S. A. Schlatter ◽  
R. N. S. Sodhi
Keyword(s):  
Structural Data ◽  
Bond Lengths ◽  
Alternative Approach ◽  
Length Data ◽  
Surface Metal ◽  
Solid Compounds ◽  
General Reliability ◽  
Predictive Approaches ◽  
Model Structures ◽  
Surface Bond

This paper compares bond lengths deduced from the methods of surface crystallography with predictions from the Pauling–Schomaker–Stevenson approach and from a new alternative approach suggested by recent work of Brown and Altermatt. Examples considered are specifically for X—M surface bond lengths where atoms X from groups 16 or 17 are adsorbed on well-defined surfaces of a metal M. The alternative approach introduced here is parametrised with reference to structural data from solid compounds of formula MX. The two predictive approaches considered, when used together, appear to be quite adequate for guiding choices of trial model structures to be included in surface crystallographic analyses with low-energy electron diffraction (LEED); also they seem reasonable for checking the general reliability (or otherwise) of surface bond length data. Two further features introduced by this work are (i) evidence that the Cl—Ag distance reported by LEED for Cl adsorbed on the Ag(100) surface is broadly consistent with the structure of solid AgCl; (ii) evidence for S adsorbed on the Fe(110) surface that these analyses can guide investigations of lateral relaxations of surface metal atoms. As more reliable structural data become available, extensions of these analyses should help to identify the finer details in X—M bond lengths which result from the special coordination arrangements occurring at surfaces.

scholarly journals Can Search Engine Advertising Help Access Rare Samples?

2011 ◽  
Vol 53 (4) ◽  
pp. 523-540 ◽  
Author(s):  
Daniel Nunan ◽  
Simon Knox
Keyword(s):  
Data Collection ◽  
Search Engine ◽  
Online Survey ◽  
Internet Survey ◽  
Barriers To Entry ◽  
Online Data ◽  
Consumer Responses ◽  
Alternative Means ◽  
General Reliability ◽  
The Cost

In the last decade, there has been an explosion in the use of online survey tools. Online data collection tools have lowered the cost of data collection and removed barriers to entry for carrying out research. While a number of questions have been raised about the general reliability of internet survey research, one specific use of the web for survey work has been in reaching niche populations that are difficult to access using traditional survey tools – so-called ‘rare samples’. In this paper, we present an approach to accessing such hard-to-reach populations using search engine pay-per-click (PPC) advertising. We carried out a study that makes uses of PPC advertising on search engines as an alternative means of developing a sample for a hard-to-reach group of health consumers. Based on a sample of 466 consumer responses, we discuss the effectiveness of this technique for reaching such rare populations.

A Systematic Approach to the Reliability Analysis of an n-Unit Warm Standby System With k-Repair Facility

2009 ◽  
Author(s):  
Yu Pang ◽  
Hong-Zhong Huang ◽  
Yu Liu ◽  
Min Xie
Keyword(s):  
Reliability Analysis ◽  
Systematic Approach ◽  
Previous Analysis ◽  
Process Theory ◽  
Repairable System ◽  
Standby System ◽  
General Reliability ◽  
Repair Facility ◽  
Traditional Approaches ◽  
Warm Standby

A systematic reliability analysis of n-unit warm standby repairable system with k-repair facility is presented in this paper. Traditional approaches are extended under the following assumptions: (1) the working lifetime, the standby lifetime, and the repair time of failed units are represented as exponential distribution; and (2) the repair of failed units are as good as new after repair. In this paper, a general reliability analysis of an n-unit warm standby repairable system with k-repair facility is presented. Based on previous analysis, the steady-state reliability and the average availability of the system are formulated using the Markov process theory and Laplace transform.

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