Application of capability indices and control charts in the analytical method control strategy

2017 ◽  
Vol 40 (15) ◽  
pp. 3046-3053 ◽  
Author(s):  
Alexis Oliva ◽  
Matías Llabres Martinez
Keyword(s):  
Control Strategy ◽  
Analytical Method ◽  
Control Charts ◽  
Capability Indices ◽  
And Control

scholarly journals Combining Capability Indices and Control Charts in the Process and Analytical Method Control Strategy

2020 ◽  
Author(s):  
Alexis Oliva ◽  
Matías Llabrés
Keyword(s):  
Control Strategy ◽  
Analytical Method ◽  
Control Charts ◽  
Process Capability ◽  
Real Data ◽  
Process Capability Indices ◽  
Specification Limits ◽  
Capability Indices ◽  
And Control ◽  
Control Limits

Different control charts in combination with the process capability indices, Cp, Cpm and Cpk, as part of the control strategy, were evaluated, since both are key elements in determining whether the method or process is reliable for its purpose. All these aspects were analyzed using real data from unitary processes and analytical methods. The traditional x-chart and moving range chart confirmed both analytical method and process are in control and stable and therefore, the process capability indices can be computed. We applied different criteria to establish the specification limits (i.e., analyst/customer requirements) for fixed method or process performance (i.e., process or method requirements). The unitary process does not satisfy the minimum capability requirements for Cp and Cpk indices when the specification limit and control limits are equal in breath. Therefore, the process needs to be revised; especially, a greater control in the process variation is necessary. For the analytical method, the Cpm and Cpk indices were computed. The obtained results were similar in both cases. For example, if the specification limits are set at ±3% of the target value, the method is considered “satisfactory” (1.22<Cpm<1.50) and no further stringent precision control is required.

scholarly journals COLLABORATIVE TRIAL AND QUALITY CONTROL IN CHEMICAL ANALYSIS

2010 ◽  
Vol 2 (3) ◽  
pp. 135-141
Author(s):  
Narsito Narsito
Keyword(s):  
Quality Control ◽  
Chemical Analysis ◽  
Analytical Method ◽  
Control Charts ◽  
Analytical Data ◽  
Control Program ◽  
Quality Parameter ◽  
Quality Control Program ◽  
And Control

Abstract                                                             This paper deals with some practical problems related to the quality of analytical chemical data usually met in practice. Special attention is given to the topic of quality control in analytical chemistry, since analytical data is one of the primary information from which some important scientifically based decision are to be made. The present paper starts with brief description on some fundamental aspects associated with quality of analytical data, such as sources of variation of analytical data, criteria for quality of analytical method, quality assurance in chemical analysis. The assessment of quality parameter for analytical method like the use of standard materials as well as standard methods is given. Concerning with the quality control of analytical data, the use of several techniques, such as control samples and control charts, in monitoring analytical data in quality control program are described qualitatively.  In the final part of this paper, some important remarks for the preparation of collaborative trials, including the evaluation of accuracy and reproducibility of analytical method are also given Keywords: collaborative trials, quality control, analytical data Abstract                                                             This paper deals with some practical problems related to the quality of analytical chemical data usually met in practice. Special attention is given to the topic of quality control in analytical chemistry, since analytical data is one of the primary information from which some important scientifically based decision are to be made. The present paper starts with brief description on some fundamental aspects associated with quality of analytical data, such as sources of variation of analytical data, criteria for quality of analytical method, quality assurance in chemical analysis. The assessment of quality parameter for analytical method like the use of standard materials as well as standard methods is given. Concerning with the quality control of analytical data, the use of several techniques, such as control samples and control charts, in monitoring analytical data in quality control program are described qualitatively.  In the final part of this paper, some important remarks for the preparation of collaborative trials, including the evaluation of accuracy and reproducibility of analytical method are also given Keywords: collaborative trials, quality control, analytical data

Dry chip feedrate control using online chip moisture

TAPPI Journal ◽  
2018 ◽  
Vol 17 (05) ◽  
pp. 295-305
Author(s):  
Wesley Gilbert ◽  
Ivan Trush ◽  
Bruce Allison ◽  
Randy Reimer ◽  
Howard Mason
Keyword(s):  
Production Rate ◽  
Control Strategy ◽  
Rate Control ◽  
Near Infrared ◽  
Dry Mass ◽  
The Other ◽  
Process Variability ◽  
Moisture Sensor ◽  
Feedback Control Strategy ◽  
And Control

Normal practice in continuous digester operation is to set the production rate through the chip meter speed. This speed is seldom, if ever, adjusted except to change production, and most of the other digester inputs are ratioed to it. The inherent assumption is that constant chip meter speed equates to constant dry mass flow of chips. This is seldom, if ever, true. As a result, the actual production rate, effective alkali (EA)-to-wood and liquor-to-wood ratios may vary substantially from assumed values. This increases process variability and decreases profits. In this report, a new continuous digester production rate control strategy is developed that addresses this shortcoming. A new noncontacting near infrared–based chip moisture sensor is combined with the existing weightometer signal to estimate the actual dry chip mass feedrate entering the digester. The estimated feedrate is then used to implement a novel feedback control strategy that adjusts the chip meter speed to maintain the dry chip feedrate at the target value. The report details the results of applying the new measurements and control strategy to a dual vessel continuous digester.

A power management and control strategy with grid-ancillary services for a microgrid based on DC Bus

2014 ◽  
Vol 9 (4) ◽  
pp. 792 ◽  
Author(s):  
Anna Pinnarelli ◽  
Giuseppe Barone ◽  
Giovanni Brusco ◽  
Alessandro Burgio ◽  
Daniele Menniti ◽  
...  
Keyword(s):  
Power Management ◽  
Control Strategy ◽  
Ancillary Services ◽  
Dc Bus ◽  
And Control

Analysis and control of the paper moisture content variability by using fuzzy and traditional individual control charts

2021 ◽  
Vol 208 ◽  
pp. 104211
Author(s):  
José L. Rodríguez-Álvarez ◽  
Rogelio López-Herrera ◽  
Iván E. Villalon-Turrubiates ◽  
Rey D. Molina-Arredondo ◽  
Jorge L. García Alcaraz ◽  
...  
Keyword(s):  
Moisture Content ◽  
Control Charts ◽  
Individual Control ◽  
And Control

scholarly journals Quantitative Correlation and Control Strategy for Element Content Fluctuation along Casting Direction in Central Area of Continuous Casting Billet

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 452
Author(s):  
Dongwei Guo ◽  
Zibing Hou ◽  
Zhiqiang Peng ◽  
Qian Liu ◽  
Jianghai Cao
Keyword(s):  
Control Strategy ◽  
Central Area ◽  
Solidification Structure ◽  
Equiaxed Crystal ◽  
Correlation Relationship ◽  
Zone Formation ◽  
Zone Width ◽  
Quantitative Correlation ◽  
Central Segregation ◽  
And Control

The statistical correlation was applied to analyze the specific and quantitative correlation relationship between the solidification structure and central segregation along the casting direction in carbon steel billet. On this basis, the segregation formation mechanism of the solute element and related control strategy were investigated. It is found that the equiaxed crystal zone fluctuation along the casting direction determines the fluctuation degree of central segregation. At the same time, the central segregation at a certain position is mostly affected by the equiaxed crystal zone width at the hysteretic position. Moreover, the casting speed can influence the columnar to equiaxed transition (CET) fluctuation along the casting direction by affecting the flow of molten steel in the billet. Overall, the segregation mechanism of solute elements along the casting direction can be summarized into two aspects: First, with the growth of columnar crystals in the initial stage, the segregated solutes are continuously enriched and distributed in the equiaxed crystal zone after CET. The fluctuation of the equiaxed crystal zone will affect the distribution of the enriched solute in the billet and cause the fluctuation of the central segregation. Second, due to the solidification shrinkage at the end of solidification, the solute-enriched liquid phase at the hysteretic position is pumped to the solidification endpoint and forms the central V-shaped segregation. Meanwhile, the stable solidification structure (columnar crystal length or equiaxed crystal zone width) along the casting direction and control measures preceded equiaxed crystal zone formation are beneficial to reduce the central V-shaped segregation.

Sign in / Sign up

Export Citation Format

Share Document