Reliability Quality Control Research Articles

Design Reliability Analysis and Quality Control of Nuclear Pressure Reducing Valve

In order to improve the localization level of nuclear power and solve the “neck” problem of nuclear pressure reducing valve in CAP1400 project, the design reliability analysis and quality control requirements of domestic prototype of nuclear pressure reducing valve was studied. Through the analysis and application of the technical requirements of the pressure reducing valve, the control was strengthened from the reliability requirements of seismic analysis, identification test and quality control points, which provided a strong technical support for the localization of nuclear grade pressure reducing valve. The seismic analysis required that the stress, resonance frequency and deformation analysis on the dangerous section of the main parts of nuclear pressure reducing valve met the requirements of regulations and standards. The reliability control was carried out from three aspects: the selection of test medium, the stability control of pressure behind the valve and the requirements of failure operation performance. Quality point control taked quality control measures from three aspects: tooling design, standard application and test bench management. All measurements ensured that the design quality of nuclear pressure reducing valve meets the requirements. The successful development of the domestic prototype of nuclear grade pressure reducing valve shows the effectiveness of the design reliability analysis and quality control method, which provides a reference for the localization of equipment in the future.

On estimation of P(Y < X) for inverse Pareto distribution based on progressively first failure censored data.

The stress-strength reliability (SSR) model ϕ = P(Y < X) is used in numerous disciplines like reliability engineering, quality control, medical studies, and many more to assess the strength and stresses of the systems. Here, we assume X and Y both are independent random variables of progressively first failure censored (PFFC) data following inverse Pareto distribution (IPD) as stress and strength, respectively. This article deals with the estimation of SSR from both classical and Bayesian paradigms. In the case of a classical point of view, the SSR is computed using two estimation methods: maximum product spacing (MPS) and maximum likelihood (ML) estimators. Also, derived interval estimates of SSR based on ML estimate. The Bayes estimate of SSR is computed using the Markov chain Monte Carlo (MCMC) approximation procedure with a squared error loss function (SELF) based on gamma informative priors for the Bayesian paradigm. To demonstrate the relevance of the different estimates and the censoring schemes, an extensive simulation study and two pairs of real-data applications are discussed.

COMPOUND RAYLEIGH LIFETIME DISTRIBUTION-I

This paper provides a new lifetime distribution model named as Compound Rayleigh Lifetime Distribution -I which is derived from Rayleigh distribution by imposing the restriction on the distribution of its parameter towards obtaining the properties of fine tuning manoeuvres and shift process in mean which is useful in reliability and statistical quality control analysis. The theoretical results obtained are illustrated with appropriate practical example.

Reliability Estimation for the Remained Stress-Strength Model under the Generalized Exponential Lifetime Distribution

A stress-strength reliability model compares the strength and stresses on a certain system; it is used not only primarily in reliability engineering and quality control but also in economics, psychology, and medicine. In this paper, a novel extension of stress-strength models is presented. The mew model is applied under the generalized exponential distribution. The maximum likelihood estimator, asymptotic distribution, and Bayesian estimation are obtained. A comprehensive simulation study along with real data analysis is performed for illustrating the importance of the new stress-strength model.

Diagnosis of injection-molded weld lines in ABS thermoplastic by polarized terahertz reflective imaging

We carry out a nondestructive study of injection-mold weld lines in an acrylonitrile butadiene styrene (ABS) thermoplastic electrical receptacle plate. Terahertz techniques show morphological features at the weld lines and reveal terahertz birefringence properties localized around the welds, indicating frozen-in molecular orientation and stress proximate to the welds. Surface acoustic microscopy corroborates the morphological features at the welds shown by terahertz imaging and also reveals anomalous mechanical properties at the weld lines. These results indicate that THz-based techniques provide nondestructive reliability assessment and quality control for injection-molded thermoplastic products.

Propellant Actuated Device for Parachute Deployment during Seat Ejection for an Aircraft Application

Propellant Actuated Devices (PAD) are installed on various combat aircraft of Air Force and Naval bases to perform extremely important operations such as parachute deployment, harness and leg restrain, cable cutting, pullers, seat ejection, bomb release or fuel tanks etc. They are basically called as gas generators. Such devices produce the high temperature and pressure combustion gases on initiation and used to perform different operations. These cartridges are single-shot operating devices. The performance of such kind of PADs cannot be tested by non-destructive techniques. Hence, cartridges are designed to function with high reliability and stringent quality control checks at all levels during entire development cycle. The safety features required during handling, storage and transportation are built in the design of PAD. The cartridges are required to undergo different exhaustive design qualification tests to qualify design aspects. Total life of 6 years is assigned to cartridge after performance degradation study of the propellant which includes 2 years installed life. This paper explains about the development aspects of PAD, its use, function, testing and performance evaluation methodology in a suitable fabricated Velocity Test Rig (VTR). The maximum slug velocity is 121.14 m/s in hot condition and minimum slug velocity is 99.14 m/s in cold condition. The main objective of this paper is to device a novel method to measure actual slug velocity of the aircraft gun inside a cartridge using VTR and Doppler RADAR.

Editors' note: Discrepancy in redetermination of SMN2 copy numbers in children with SMA

In the article, “Discrepancy in redetermination of SMN2 copy numbers in children with SMA,” Drs. Schorling et al. evaluated the accuracy of initial SMN2 copy number determination by repeating genetic testing in 20 patients with spinal muscular atrophy (SMA) using Multiplex Ligation-dependent Probe Amplification (MPLA) analysis. They found that the results of the second testing were discrepant to initial testing in 45% of patients, concluding that reliability testing and quality control procedures are essential before SMN2 copy numbers can be used for clinical decisions and interpretation of outcome data. In response, Drs. Dangouloff et al. reported having observed high rates of discrepancy between the results for SMN2 copy number obtained from their laboratory and other laboratories where their patients were initially tested. They report finding an overall agreement rate of just 31% for SMN2 copy number for 35 patients when testing their samples using 2 different MPLA methods in their own laboratory. They conclude that better standardization of SMN2 copy number testing is needed before these results guide decision-making in the setting of newborn screening. Responding to these comments, the authors note that they switched from the P021-A2 kit the P021-B1 kit (both methods used by Drs. Dangouloff et al.) in March 2019 and found identical results when running 3 probes with variable SMN1 / SMN2 copies with both kits and found an extra copy of exon 1-6 in 12% of the 77 individuals whose samples they subsequently analyzed. They suggest that it is critical to use reliable controls with DNA isolated from the same tissue in every MPLA run. This exchange highlights the difficulties of standardizing quantitative genetic testing techniques across different laboratories—particularly for relatively rare diseases for which it may be challenging to build domain-specific laboratory expertise, but the results nevertheless guide potentially game-changing decisions for patients. In the article, “Discrepancy in redetermination of SMN2 copy numbers in children with SMA,” Drs. Schorling et al. evaluated the accuracy of initial SMN2 copy number determination by repeating genetic testing in 20 patients with spinal muscular atrophy (SMA) using Multiplex Ligation-dependent Probe Amplification (MPLA) analysis. They found that the results of the second testing were discrepant to initial testing in 45% of patients, concluding that reliability testing and quality control procedures are essential before SMN2 copy numbers can be used for clinical decisions and interpretation of outcome data. In response, Drs. Dangouloff et al. reported having observed high rates of discrepancy between the results for SMN2 copy number obtained from their laboratory and other laboratories where their patients were initially tested. They report finding an overall agreement rate of just 31% for SMN2 copy number for 35 patients when testing their samples using 2 different MPLA methods in their own laboratory. They conclude that better standardization of SMN2 copy number testing is needed before these results guide decision-making in the setting of newborn screening. Responding to these comments, the authors note that they switched from the P021-A2 kit the P021-B1 kit (both methods used by Drs. Dangouloff et al.) in March 2019 and found identical results when running 3 probes with variable SMN1 / SMN2 copies with both kits and found an extra copy of exon 1-6 in 12% of the 77 individuals whose samples they subsequently analyzed. They suggest that it is critical to use reliable controls with DNA isolated from the same tissue in every MPLA run. This exchange highlights the difficulties of standardizing quantitative genetic testing techniques across different laboratories—particularly for relatively rare diseases for which it may be challenging to build domain-specific laboratory expertise, but the results nevertheless guide potentially game-changing decisions for patients.

Considerations for Mean Upper Cervical Cord Area Implementation in a Longitudinal MRI Setting: Methods, Interrater Reliability, and MRI Quality Control.

Spinal cord atrophy is commonly measured from cerebral MRIs, including the upper cervical cord. However, rescan intraparticipant measures have not been investigated in healthy cohorts. This study investigated technical and rescan variability in the mean upper cervical cord area calculated from T1-weighted cerebral MRIs. In this retrospective study, 8 healthy participants were scanned and rescanned with non-distortion- and distortion-corrected MPRAGE sequences (11-50 sessions in 6-8 months), and 50 participants were scanned once with distortion-corrected MPRAGE sequences in the Day2day daily variability study. From another real-world observational cohort, we collected non-distortion-corrected MPRAGE scans from 27 healthy participants (annually for 2-4 years) and cross-sectionally from 77 participants. Statistical analyses included coefficient of variation, smallest real difference, intraclass correlation coefficient, Bland-Altman limits of agreement, and paired t tests. Distortion- versus non-distortion-corrected MPRAGE-derived mean upper cervical cord areas were similar; however, a paired t test showed incomparability (t = 11.0, P = <.001). Higher variability was found in the mean upper cervical cord areas calculated from an automatic segmentation method. Interrater analysis yielded incomparable measures in the same participant scans (t = 4.5, P = <.001). Non-distortion-corrected mean upper cervical cord area measures were shown to be robust in real-world data (t = -1.04, P = .31). The main sources of variability were found to be artifacts from movement, head/neck positioning, and/or metal implants. Technical variability in cord measures decreased using non-distortion-corrected MRIs, a semiautomatic segmentation approach, and 1 rater. Rescan variability was within ±4.4% for group mean upper cervical cord area when MR imaging quality criteria were met.

Improvement of competitive edge of precast reinforced concrete by increasing the reliability level and quality control

Improvement of the competitive edge of precast reinforced concrete is necessary to achieve due to the high quality and level of reliability. Previously, it can be concluded that there is significant potential to increase the level of reliability of precast structures by improving the quality of concrete and control. The advantages of precast concrete were considered in the paper. Changes of requirements of modern standards to the quality indicators of concrete strength including coefficient of variation of concrete strength properties were analysed. Assessment of the influence of the stability of precast reinforced concrete structures production due to such quality indicators as the coefficient of variation of the concrete strength and the accuracy of the cross section of precast elements was performed. The estimation of the variation coefficient of concrete strength from 9 to 13% in accordance with the changes in the modern regulatory documents was carried out in the paper. The results of the calculations show that the decrease of the reliability level takes place up to 30%.

Tolerance–reliability analysis of mechanical assemblies for quality control based on Bayesian modeling

PurposeThe purpose of this paper is to present a new efficient method for the tolerance–reliability analysis and quality control of complex nonlinear assemblies where explicit assembly functions are difficult or impossible to extract based on Bayesian modeling.Design/methodology/approachIn the proposed method, first, tolerances are modelled as the random uncertain variables. Then, based on the assembly data, the explicit assembly function can be expressed by the Bayesian model in terms of manufacturing and assembly tolerances. According to the obtained assembly tolerance, reliability of the mechanical assembly to meet the assembly requirement can be estimated by a proper first-order reliability method.FindingsThe Bayesian modeling leads to an appropriate assembly function for the tolerance and reliability analysis of mechanical assemblies for assessment of the assembly quality, by evaluation of the assembly requirement(s) at the key characteristics in the assembly process. The efficiency of the proposed method by considering a case study has been illustrated and validated by comparison to Monte Carlo simulations.Practical implicationsThe method is practically easy to be automated for use within CAD/CAM software for the assembly quality control in industrial applications.Originality/valueBayesian modeling for tolerance–reliability analysis of mechanical assemblies, which has not been previously considered in the literature, is a potentially interesting concept that can be extended to other corresponding fields of the tolerance design and the quality control.

Rapid detection of ultra-trace nanoparticles based on ACEK enrichment for semiconductor manufacturing quality control

Commercial fabrication of semiconductor circuits is currently conducted with nanometer resolution. As a result, trace amount of nanoparticles in semiconductor processing fluids have a great influence on the yield of semiconductor chips, which was only a minor problem in the past when semiconductors were processed at larger critical dimensions. Therefore, a highly sensitive and rapid method for the online detection of nanoparticles is highly sought after by semiconductor industry. The work presents a highly sensitive, easy to do, and rapid method for detection of nanoparticles in liquid, which is based on AC electrokinetics enhanced capacitive-sensing method using commercial microelectrode chips. The detection limit reaches as low as 0.1 part per trillion with a response time of 60 s. Testing conditions of AC voltage and frequency were also investigated to obtain the optimized test parameters. Compared with the other existing detection methods, this method is highly sensitive, of low cost and with a fast response, which is important to realize high-efficiency and -reliability quality control of semiconductor process.

Modeling of real-time reliability prediction system for anisotropic conductive film (ACF) processing

This paper models a real-time reliability prediction system for application in the anisotropic conductive film (ACF) manufacturing process. The prediction system contains three major hardware/software components, namely an X-ray detection apparatus, finite element method (FEM) modeling and simulations, and post-manufacturing reliability analysis and quality control. Initially, an X-ray detection apparatus is used to scan the particle distribution in the ACF as it flows towards the roller. In the scanning operation, the coordinates of each particle are obtained and passed to a PC. Based on this scanning information, a FEM computational mesh of the ACF sample is generated in which each grid node corresponds to an individual particle. The ACF mesh is then integrated with an FEM model of the IC/substrate assembly and the relevant geometry parameters defined, i.e. the pad height, the pad length, the pad pitch, and the particle radius. Compression simulations are performed using DEFORM or ALPID software and the corresponding particle flow and redistribution calculated. A reliability analysis of the redistributed particle pattern is then performed based upon the probabilities of both opening and bridging effects. The real-time reliability prediction system modeled in this paper provides an effective reliability analysis and quality control scheme for the processing of ACF compounds.

DC-DC CONVERTER RELIABILITY: DESIGN, COMPONENTS AND QUALIFICATION

This paper provides a comprehensive study on reliability issues related to DC-DC converter design. First of all, some common reliability issues and DC-DC converter design topologies are discussed. Then, a reliability sensitivity study results on an industry standard VRM is presented using a prediction-based design-for-reliability and sensitivity analysis tool created by the author and colleagues at HP. The thermal design issues and component derating in the converter design are discussed. Since electronic component reliability has been a bottleneck in DC-DC converter reliability, the component reliability issues are discussed and some reliability application guidelines are also provided for the DC-DC converters reliability design. In the last part of the paper, an integrated reliability testing, qualification, and quality control procedure is presented using highly accelerated testing methodology. The use of this procedure by HP on DC-DC converter reliability and quality control has shown promising results.

The product and quotient of general beta distributions

The general beta distribution in 4 parameters, denoted gbeta (α, β; c, d), defined on the interval (c,d) is one of the most useful distributions in statistical applications and in related fields such as Operations Research and Management Science. We give here the exact expressions of the densities of X1X2 and of X1/X2, where X1 and X2 are independent general beta variables, and discuss the relationships between the new results with those already obtained. Applications in Reliability and Bayesian Quality Control are given. A computer program, developed for hypergeometric functions in general, can be used to carry out the precise computation of these densities.

A Statistical Model for Prediction of Tool Life as a Basis for Economical Optimization of the Cutting Process

Summary The paper is dedicated to the implementation of statistical optimization of the cutting process by identification and prediction of the tool condition and lifetime. A statistical model is presented which uses ideas from the theory of reliability and statistical quality control. Since the model is consistent with the Taylor equation, it can easily utilize existing information about relations between cutting data and tool life. A control strategy, which is based on the model, is put forward. Results from experimental tests of the statistical model and of the influence on the wear rate due to feed variations as well as of the performance of the control algorithm are presented.

Design of metallization equipment for web coating

As a result of the increasing demands created by the wide range of such applications as decorative, packaging, energy conservation and electronic materials, the continuous web metallizing process has become sophisticated and exacting. High system reliability and precise quality control are required to achieve the continuous deposition of thin metallic coatings onto polyester films, paper and cloth in roll form. An in-depth discussion of the critical areas in the design and operation of equipment, together with the various deposition processes, is presented, with emphasis on the significance of vacuum level, uniformity of coating thickness and web transport properties, such as tension and temperature control.

Manual of Product Assurance Films on Reliability Engineering and Management, Reliability Testing, Maintainability, and Quality Control

Manual of Product Assurance Films on Reliability Engineering and Management, Reliability Testing, Maintainability, and Quality Control

Manual of Product Assurance Films on Reliability Engineering and Management, Reliability Testing, Maintainability, and Quality Control

Manual of Product Assurance Films on Reliability Engineering and Management, Reliability Testing, Maintainability, and Quality Control

Increased Reliability and Better Quality Control through Mechanized Assembly and Test

It is pointed out that the electronics industry long a heavy contributor to automation in other industries, has until recently been in the role, one might say, of the cobbler's son who goes barefoot. Bast and future expansion of the electronics industry is charted, as it is estimated that an all-out national emergency would demand an output of 10 times our present production rate. Automation is posed as a solution to this dilemma; as well as an aid to uniformity, miniaturization, conservation, quality, and reliability. Changing production requirements are cited. It is also emphasized that the product, the process, or both must be completly changed in order to make automatic production feasible. Two automation approaches are discussed: that of the component-parts manufacturer, and that of the equipment assembler. Three machines are described: a simple bench-type individual-insertion machine, a fully-automatic in-line insertion machine, and an automatic forced-area dip-soldering machine. Assembly efficiency of the in-line machine is charted in detail (for early 1956 operation). A 7½ % rework rate is quoted without insertion inspection, and a 0.07 % rate with insertion inspection. The need for greater reliability is stressed, and attainment of this greater reliability through automatic assembly anti automatic test is treated at some length. In conclusion, the author admits that the present state of the art leaves much to be desired, as we build new machines and modify our products for mass-production suitability. Yet high hopes are expressed that much simpler quality-control procedures and ranch more uniform products will give considerably more reliable equipment in the field-- and this, in the not too distant future.