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•A novel arginine-functionalized polyaniline@FeOOH composite was synthesized.•The as-developed composite provides superior cleanup ability and selectivity for Cr(VI) ions from ...water.•Electrostatic attractions controlled the Cr(VI) adsorption process.•The process capability study reveals the suitability of Cr(VI) adsorption for large scale application.•Arg-PANI@FeOOH exhibits excellent re-generability and reusability for Cr(VI) ions removal.
In this study, the synthesis of a novel arginine-functionalized polyaniline/FeOOH (Arg-PANI@FeOOH) composite for hazardous Hexavalent chromium ions (Cr(VI)) removal from wastewater was reported. The SEM, EDS, FTIR, XRD, and PZC measurements were used to characterize the as-developed Arg-PANI@FeOOH composite. Batch adsorption experiments were used to investigate the influence of pH, temperature, contact time, Arg-PANI@FeOOH amount, initial Cr(VI) concentration and coexisting ions on the efficiency of Cr(VI) removal. The Cr(VI) adsorption was much more advantageous at lower pH values, reflecting that the electrostatic interactions were the main driving forces that govern Cr(VI) binding mechanism on the Arg-PANI@FeOOH surface. The experimental data showed good fitness to the pseudo-second-order kinetics and Langmuir isotherm. The Cr(VI) species highest monolayer coverage capacity onto Arg-PANI@FeOOH was 682.30 mg g−1. The adsorption of Cr(VI) onto the Arg-PANI@FeOOH is spontaneous via an endothermic reaction. The competing anions were not affected the Cr(VI) adsorption, demonstrating that the Arg-PANI@FeOOH selectively adsorb Cr(VI) ions. The developed Arg-PANI@FeOOH material demonstrated good reusability up to five regeneration cycles. The process capability to predict the practical aptitude of Arg-PANI@FeOOH adsorbent to remove Cr(VI) from aqueous solutions was successfully applied. As a result, the adsorption of Cr(VI) onto Arg-PANI@FeOOH composite is a capable process for full-scale wastewater purification purposes. This paper provides relevant findings for a polyaniline-based adsorbent for the efficient removal of Cr(VI) from wastewater.
•Inappropriate plan parameter derivation for variables sampling plans is addressed.•The actual α‐risk might be larger than the maximum one desired by the producer.•Correct plan parameters are ...recalculated to overwrite those in the original papers.•Two applicative examples show practical consequences of the proposed corrections.
In this short note, we prove that the derivation of the required sample size and critical acceptance value under the normality assumption of the quality characteristic proposed by Wu, C. W., Aslam, M., & Jun, C. H. (2012). Variables sampling inspection scheme for resubmitted lots based on the process capability index Cpk. European Journal of Operational Research, 217(3), 560–566, is inappropriate. In fact, it leads to a lower probability of acceptance than the one desired by the producer. The same issue also occurs in the case of a variables single sampling plan described in a previous paper by Pearn, W. L., & Wu, C. W. (2007). An effective decision making method for product acceptance. Omega, 35(1), 12–21. Nevertheless, a similar yet less severe inaccuracy is also noticed in Wu, C. W., & Pearn, W. L. (2008). A variables sampling plan based on Cpmk for product acceptance determination. European Journal of Operational Research, 184(2), 549–560.
This research aims to identify one of the methods of statistical quality control, which is represented in the indicators of the Capability Process and explains its importance and how to use it for ...knowing the extension of the process to fulfill the specifications through several indicators with a statement that through practical application on one of the pharmaceutical products (Paramol Tablets Weights) one of the products of Yemeni Drug Company for Industry and Commerce (YEDCO). Hence, the results showed that the permits of process specifications of the tablet weight are equal to about 5 standard deviations, which is less than the standard practices, which are 8 standard deviations. Therefore, the capacity of the process for tablet weight is Cp<1, which is an undesirable state; because the production process is unable to satisfy the specifications. The CPK indicator shows that the process is decentralized and hence the inability of the process to fulfill the specifications; therefore, the company has to revise the limits of Paramol tablet weights specifications and to expand it as the company adopts numerous pharmacopeias in its operations. It must select the pharmacopeia that gives specifications which can make the process capability indicator and the index of process concentration in their standard state (Cp, Cpk=1.33mg).
•We propose a fuzzy-inference-based decision-making method for PCA.•The method enables users to select optimal PCIs using fuzzy logic for K and Zshift.•The PCA results are reported via the dashboard ...of our decision-making system.•The proposed method was applied to a manufacturing process for home gas boilers.
This paper proposes a decision-making method based on fuzzy inference to facilitate process capability analysis based on the knowledge and experience of experts, and implement systematized statistical process capability control. Data screening is implemented in the form of a rule-based decision-making tree to perform normality testing, R- or s-control chart testing, and x-bar control chart testing on process data to determine whether a process is in a state of statistical control. After setting the improvement direction of the process using a four-block diagram, the processes with a high probability of defect leakage due to large dispersion compared to the specification are reexamined after the fundamental improvement is completed by reinforcing the technology. Additionally, an optimal process capability index is selected using fuzzy inference by considering the degree of bias in a distribution and the differences between short- and long-term process capabilities. The feasibility of the proposed method was verified by applying it to a process for manufacturing home gas boilers. The method enables process control engineers to examine the results of the statistical analysis and the priority of the process to be improved, which are visualized in real time using a dashboard. These results are subsequently used for decision-making.
Process capability indices such as C
p
, C
pL
, C
pU
, and C
pk
have been used for evaluating the performance of a manufacturing process in statistical quality control and statistical process control ...fields. In this paper, a Bayes estimator of C
pk
is constructed such that the prior mean is set to be equal to a specified value while the prior distribution is weakly informative. This estimator is compared with conventional Bayes and non Bayes estimators.
Purpose
The purpose of this paper is to establish mechanisms for process improvement so that production efficiency and product quality can be expected, and create a sustainable development in terms ...of circular economy.
Design/methodology/approach
The authors obtain a critical value from statistical hypothesis testing, and thereby construct a process capability indices chart, which both lowers the chance of quality level misjudgment caused by sampling error and provides reference for the processes improvement in poor quality levels. The authors used the bottom bracket of bicycles as an example to demonstrate the model and methods proposed in this study.
Findings
This approach enables us to plot multiple quality characteristics, despite varying attributes and specifications, onto the same process capability analysis chart. And it therefore increases accuracy and precision to reduce rework and scrap rates (reduce), increase product availability, reduce maintenance frequency and increase reuse (reuse), increase the recycle rates of components (recycle) and lengthen service life, which will delay recovery time (recovery).
Originality/value
Parts manufacturers in the industry chain can upload their production data to the cloud platform. The quality control center of the bicycle manufacturer can utilized the production data analysis model to identify critical-to-quality characteristics. The platform also offers reference for improvement and adds the improvement achievements and experience to its knowledge management to provide the entire industry chain. Feedback is also given to the R&D department of the bicycle manufacturer as reference for more robust product designs, more reasonable tolerance designs, and selection criteria for better parts suppliers, thereby forming an intelligent manufacturing loop system.
Process Capability Indices such as Process Capability Index (Cp) and Corrected Process Capability Index (Cpk), along with Process Performance Index (Pp) and Process Performance Corrected Index (Ppk), ...are most commonly used tools in quality management within manufacturing processes. They determine whether a process is capable of producing products within established tolerance limits, addressing both short-term and long-term variability. Despite widespread use, the analysis of Process Capability Indices often overlooks special variability within processes, which may lead to misleading interpretations of a process's capability, especially when the determination of tolerance limits is inadequately conducted. This article aims to verify the hypothesis that current analyses of Process Capability Indices fail to consider special variability, which could mislead the interpretation of a process's ability to meet its specifications. Statistical analyses were conducted using the Minitab software, based on dynamic viscosity measurements from the production process of solvent-based paint, to explore the implications of special variability on the interpretation of Process Capability Indices. The study revealed that while Process Capability Indices are useful for identifying quality management opportunities, their effectiveness is limited when special variability is present, often resulting in misinterpretations of a process's true capabilities. The findings highlight the need for methodologies that incorporate considerations of all forms of variability to ensure accurate process capability assessments. This gap in traditional analyses can affect the strategic decision-making in quality management, suggesting a critical area for further research and methodological development. The research confirms the need for a revised approach in analyzing Process Capability Indices, advocating for advanced methods that accurately reflect all forms of variability to improve quality management practices. Future research should focus on developing these methodologies to ensure more reliable and effective use of Process Capability Indices in quality management.
Variables Quick-Switch Sampling Systems (VQSSs) that involve both normal and tightened inspections for lot dispositions have attracted significant attention and discussion. However, existing VQSS ...models exhibit limitations, particularly in their rule-switching mechanism. Practitioners may encounter situations where multiple rounds of tightened inspection are necessary to ensure submission quality when suspicions of process degradation arise. Current VQSS models do not effectively address this need. To overcome this limitation, we present VQSSG by integrating a VQSS with a generalized rule-switching mechanism and the widely used capability index Cpk. VQSSG offers practitioners the flexibility to specify the number of successive lot acceptances under tightened inspection before transitioning to normal inspection. Our research includes the derivation of operating characteristics and average sample number functions for VQSSG, based on the Cpk index. Through in-depth investigations, we construct nonlinear optimisation models to determine the optimal system design and identify distinct types and settings for VQSSG, highlighting its strengths and weaknesses. Additionally, we provide managerial insights and recommendations for the effective implementation and application of VQSSG. To validate the practicality of this system, an industrial case study is presented. This paper significantly enhances the efficiency and adaptability of sampling systems by introducing VQSSG. The findings and managerial suggestions contribute to a deeper understanding of potential real-world applications, thereby enhancing quality control and decision-making processes.
•A generalized sampling system with a flexible decision-rule mechanism is proposed.•The proposed system shows superior cost efficiency in inspections.•The proposed system excels in detecting quality degradation in inspected lots.•The proposed method is validated through an industrial case study.•A web-based application is developed to assist in obtaining optimal system design.
•A novel PCAC to measure products with multi-quality characteristic.•Pareto optimality to achieve the performance optimization for CM selection.•A feedback mechanism to advise ineligible CMs on ...quality issues.•A rigid coupling to validate the proposed methodology.
Outsourcing is a crucial strategy of the mechanical manufacturing industry. When outsourcing, it is necessary for companies to carefully inspect the performance of contract manufacturers (CMs) to ensure high-quality products and satisfactory services. This study presents an integrated methodology for the quality performance assessment and optimization of products with multiple quality characteristics for CM selection in the mechanical manufacturing industry. First, we present a novel process capability analysis chart (PCAC) using the 100(1–α)% upper confidence limits of Cpmh, Cpuh, and Cplh to gauge the process capabilities of products with multiple quality characteristics and reduce the influence of sampling errors. Second, we apply Pareto optimality to reexamine eligible CMs under the objectives of maximizing performance in individual quality characteristics and minimizing variance in overall performance. A feedback mechanism is included to advise ineligible CMs on means of improvement. Finally, we present a case study to demonstrate the feasibility and effectiveness of the proposed methodology.
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