Modified Multivariate Process Capability Index Using Principal Component Analysis

The existing research of process capability indices of multiple quality characteristics mainly focuses on nonconforming of process output, the concept development of tmivariate process capability indices, quality loss function and various comprehensive evaluation methods. The multivariate complexity increases the computation difficulty of multivariate process capability indices（MPCI）, which makes them hard to be used in practice. In this paper, a new PCA-based MPCI approach is proposed to assess the production capability of the processes that involve multiple product quality characteristics. This approach first transforms the original quality variables into standardized normal variables. MPCI measures are then provided based on the Taam index. Moreover, the statistical properties of these MPCIs, such as confidence intervals and lower confidence bound, are given to let the practitioners understand the capability indices as random variables instead of deterministic variables. A real manufacturing data set and a synthetic data set are used to demonstrate the effectiveness of the proposed method. An implementation procedure is also provided for quality engineers to apply our MPCI approach in their manufacturing processes. The case studies demonstrate the effectiveness and feasibility of this new kind of MPCI, which is easier to be used in production practice. The proposed research provides a novel approach of MPCI calculation.

A multivariate process capability index model system

This paper presents a systematic multivariate process capability index （MPCI） method, which may provide references for assuring and improving process quality levels while achieving an overall evaluation of process quality. The system method includes a spatial MPCI model for multivariate normal distribution data, MPCI model based on factor weight for multivariate no-normal distribution application, and MPCI model based on yield foryield application. At last, examples for calculating MPCI are given, and the experimental results show that this systematic method is effective and practical.

A multivariate process capability index with a spatial coefficient

After analyzing the multivariate Cpm method （Chan et al. 1991）, this paper presents a spatial multivariate process capability index （PCI） method, which can solve a multivariate off-centered case and may provide references for assuring and improving process quality level while achieving an overall evaluation of process quality. Examples for calculating multivariate PCI are given and the experimental results show that the systematic method presented is effective and actual.

Design of an Index System for Deep Groundwater Management Efficiency Evaluation: A Case Study in Tianjin City, China

An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index system is specifically developed to evaluate deep groundwater management efficiency. It is composed of three first-level indicators(law enforcement capability, management ability, and management effectiveness) and eleven second-level indicators. The second-level indicators include seven mandatory indicators and four optional indicators. Piecewise linear function is used to normalize the quantitative indicators, and expert scoring method and questionnaire survey method are used to normalize the qualitative indicators. Then a comprehensive indicator weighting evaluation method is used to evaluate the first-level indicators and the target topic. A case study is carried out to evaluate deep groundwater management efficiency in Tianjin City. According to the evaluation score in each period, the management efficiency of every district in Tianjin City gradually improved. The overall evaluation score in the early deep groundwater extraction period is 0.12. After a series of deep groundwater protection efforts, this score reached to 0.61 in 2007, and met the regulation criteria. The evaluation results also showed that the further groundwater management efforts in Tianjin City should be focused on building a dynamic database to collect comprehensive deep well-log data; and on a reasonable design and distribution of the groundwater monitoring network. It demonstrated that the index system is suitable to locate the deficiencies of current groundwater management systems and to guide further improvements. It can then be used to protect deep groundwater.

DC faults ride-through capability analysis of Full-Bridge MMC-MTDC System

Full-Bridge Modular Multilevel Converter(FBMMC) has strong ability to ride through serious DC faults,thus it is very suitable for multi-terminal flexible HVDC applications.However,no references have reported the locating and isolating of DC faults and corresponding DC faults ride-through capability evaluation index.This paper introduces the topology mechanism of FBMMC and its loss reduction operation mode,theoretically certifies that the universal decoupled control strategy of Voltage Source Converter(VSC) and the similar modulation strategies of Half-Bridge MMC(HBMMC) can be applied to FBMMC for constructing complete closed-loop control system.On the basis of the existing DC faults locating and isolating schemes of 2-level VSC based Multi-Terminal HVDC(VSC-MTDC) system and the particularity of FBMMC,this paper proposes the DC faults wire selection "handshaking" method of the FBMMC-MTDC system,and proposes the DC Fault Ride-Through Capability Index(DFRTI) for evaluating the DC faults suppressing capability of the VSC-MTDC systems,including FBMMC-MTDC.Simulations of FBMMC-MTDC in PSCAD/EMTDC validate the correctness and effectiveness of the proposed control strategy and evaluation index.

Evolution of process capability in a manufacturing process

Before mass production of individual components industries may assess its capability to produce it according to specifications.This capability assessment is a common requirement in the automotive sector.This work shows a case study,providing an in-depth analysis,on a critical component and finds evidence of process degradation over two years of production,quantified through capability analysis.At pre-production,it was concluded that the process was capable and,thus,no statistical process control was done during its production.Over the months no defective units were detected but then its level began to increase and it was apparent that process variability had increased and the process was no longer capable.Process improvement activities were developed using known quality tools and methodologies.This work shows how the control plan initially defined became obsolete and discusses the need to periodically review quality control mechanisms.

Data-driven engineering framework with AI algorithm of Ginkgo Folium tablets manufacturing

Smart manufacturing still remains critical challenges for pharmaceutical manufacturing.Here,an original data-driven engineering framework was proposed to tackle the challenges.Firstly,from sporadic indicators to five kinds of systematic quality characteristics,nearly 2,000,000 real-world data points were successively characterized from Ginkgo Folium tablet manufacturing.Then,from simplex to the multivariate system,the digital process capability diagnosis strategy was proposed by multivariate C_(pk)integrated Bootstrap-t.The C_(pk)of Ginkgo Folium extracts,granules,and tablets were discovered,which was 0.59,0.42,and 0.78,respectively,indicating a relatively weak process capability,especially in granulating.Furthermore,the quality traceability was discovered from unit to end-to-end analysis,which decreased from 2.17 to 1.73.This further proved that attention should be paid to granulating to improve the quality characteristic.In conclusion,this paper provided a data-driven engineering strategy empowering industrial innovation to face the challenge of smart pharmaceutical manufacturing.

A FRAMEWORK OF SETTING UP GOAL CONTROL LIMITS OF TARGET COSTING FOR NON-NORMAL DISTRIBUTIONS

This study provides a framework of target costing to extend its original scope when the underlying distribution is non-normal. The new specification limits can be derived by listening to the market price from Taguchi loss function. Later, the new specification limits can be linked through the non-normality-based C^^pk value along with non-normality-based X^^-Rcontrol charts to derive goal control limits. Moreover, an example is provided to illustrate the usefulness of the proposed framework of target costing by relentlessly reducing cost and improving product quality to gain competitiveness in the marketplace.