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The Consequences of Implementing Statistical Process Control

Description: This study evaluated the changes which occur in manufacturing organizations in the plastic molding industry which implement statistical process control (SPC). The study evaluated changes in product quality, consistency, cost, changes in employee attitudes, and changes in the organization structure which occur after the implementation of SPC. The study was conducted in two phases. Phase 1 consisted of an exploratory field study of a single manufacturing company. Phase 2 consisted of a field survey of three manufacturing companies in the same industry. An unexpected opportunity to evaluate the differences in effects of successful and unsuccessful SPC implementations occurred during the field survey. One plant, whose management assessed their SPC program as being unsuccessful, reported no economic or quality benefits from SPC. Neither did this plant report any changes in the attitudes or behavior of their employees. Neither of these findings was surprising since this plant was the only one of the four study plants which implemented SPC as a quality control program with no participation from the production department. The three plants whose management assessed their SPC programs as being successful reported reduced product variation and a decrease in the proportion of defective product produced as a result of SPC. No consistent evidence was found concerning a reduction in the material required per product resulting from SPC. No consistent evidence was found linking changes in employee attitudes and behavior to the implementation of SPC. The field study found a significant change in the employees1 attitudes toward management but no change in their attitudes toward the company. The field survey found no evidence of change in either dimension. Evidence was found for a change to a more organic structure during SPC training and to a more mechanistic structure during SPC implementation. The final form of the organization was more organic than ...
Date: August 1990
Creator: Sower, Victor E.
Partner: UNT Libraries

Statistical process control (SPC) for coordinate measurement machines

Description: The application of process capability analysis, using designed experiments, and gage capability studies as they apply to coordinate measurement machine (CMM) uncertainty analysis and control will be demonstrated. The use of control standards in designed experiments, and the use of range charts and moving range charts to separate measurement error into it's discrete components will be discussed. The method used to monitor and analyze the components of repeatability and reproducibility will be presented with specific emphasis on how to use control charts to determine and monitor CMM performance and capability, and stay within your uncertainty assumptions.
Date: January 4, 2000
Creator: Escher, R. N.
Partner: UNT Libraries Government Documents Department

An Adaptive System for Process Control

Description: Abstract: Researchers at the U.S. Bureau of Mines (USBM) have developed adaptive process control systems in which genetic algorithms (GA's) are used to augment fuzzy logic controllers (FLC's). GA's are search algorithms that rapidly locate near-optimum solutions to a wide spectrum of problems by loosely modeling the search procedures of natural genetics. FLC's are rule-based systems that efficiently manipulate a problem environment by modeling the "rule-of-thumb" strategy used in human decisionmaking. Together, GA's and FLC's include all of the capabilities necessary to produce powerful, efficient, and robust adaptive control systems. To perform efficiently, such control systems require a cont element to manipulate the problem environment, an analysis element to recognize changes in the problem environment, and an adaptive element to adjust to the changes in the problem environment. The control system also employs a computer simulation of the problem environment. Details of an overall adaptive control system are discussed. A specific laboratory acid-base pH system is used to demonstrate the ideas presented; all results are from the physical laboratory system and not from a computer simulation.
Date: 1995
Creator: Karr, Charles L.; Gentry, E. J. & Stanley, D. A.
Partner: UNT Libraries Government Documents Department

Proceedings of the 1981 Symposium on Instrumentation and Control for Fossil-Energy Processes: June 8-10, 1981 Sheraton-Palace Hotel, San Francisco, California

Description: Compiled proceedings of the fifth Symposium on Instrumentation and Control for Fossil-Energy Processes, covering process control involved in the conversion of fossil fuels into synthetic fuels.
Date: January 1982
Creator: Argonne National Laboratory
Partner: UNT Libraries Government Documents Department

Emerging standards with application to accelerator safety systems

Description: This paper addresses international standards which can be applied to the requirements for accelerator personnel safety systems. Particular emphasis is given to standards which specify requirements for safety interlock systems which employ programmable electronic subsystems. The work draws on methodologies currently under development for the medical, process control, and nuclear industries.
Date: August 1, 1997
Creator: Mahoney, K.L. & Robertson, H.P.
Partner: UNT Libraries Government Documents Department

Project B: Improved Liquid Steel Feed For Slab Casters

Description: This report describes the completion of the development of an electromagnetic valve to control liquid steel flow for improved liquid steel feeding for slab casters. Achievements result from a joint research effort between Westinghouse Science and Technology Center, North American Refractories and U.S. Steel. This effort is part of the American Iron and Steel Institute's (AISI) Advanced Process Control Program, a collaboration between the U.S. Department of Energy (DOE) and fifteen North American steel makers.
Date: October 1, 1998
Creator: Isaacson, Brent S.; Slepian, Mike & Richter, Thomas
Partner: UNT Libraries Government Documents Department


Description: We summarize the ECL2 workshop on electron cloud clearing, which was held at CERN in early March 2007, and highlight a number of novel ideas for electron cloud suppression, such as continuous clearing electrodes based on enamel, slotted structures, and electrete inserts.
Date: April 9, 2007
Creator: FISCHER,W.
Partner: UNT Libraries Government Documents Department

Adaptive control of femtosecond pulse propagation in optical fibers

Description: We present an adaptive control loop that synthesizes fs-pulses that are self-correcting for higher order nonlinear effects when launched in a conventional single-mode fiber, nearly preserving the initial (t{approx}200 fs) pulse duration.
Date: January 1, 2001
Creator: Omenetto, F. G. (Fiorenzo G.); Taylor, Antoinette J.,; Moores, M. D. (Mark D.) & Reitze, David H.
Partner: UNT Libraries Government Documents Department

Wet-Etch Figuring Optical Figuring by Controlled Application of Liquid Etchant

Description: WET-ETCH FIGURING (WEF) is an automated method of precisely figuring optical materials by the controlled application of aqueous etchant solution. This technology uses surface-tension-gradient-driven flow to confine and stabilize a wetted zone of an etchant solution or other aqueous processing fluid on the surface of an object. This wetted zone can be translated on the surface in a computer-controlled fashion for precise spatial control of the surface reactions occurring (e.g. chemical etching). WEF is particularly suitable for figuring very thin optical materials because it applies no thermal or mechanical stress to the material. Also, because the process is stress-free the workpiece can be monitored during figuring using interferometric metrology, and the measurements obtained can be used to control the figuring process in real-time--something that cannot be done with traditional figuring methods.
Date: February 13, 2001
Creator: Britten, J
Partner: UNT Libraries Government Documents Department

Evaluation and Development of a Prototype Electrokinetic Sonic Amplitude (ESA) System for On-Line Measurement of Charge in Papermaking Process Streams

Description: The papermaking industry uses an abundance of chemicals to control the process of papermaking. These chemicals are used to control everything from paper strength to brightness. Due to the natural variability of products used in papermaking, the chemistry of the process is heavily monitored. Cationic (charge) demand is one of the most important parameters in process control of papermaking. High variations in cationic demand result in off-spec final product or paper breaks resulting in wasted production and downtime. Both of these results are costly for papermakers due to high energy consumption and loss of revenue. Currently, cationic demand is measured off-line in a laboratory setting with a heavily diluted specimen taking up to hours for results. The industry need is for an on-line, real-time measurement of cationic demand at higher consistencies to provide control feedback for the addition of cationic demand at higher consistencies to provide control feedback for the addition of cationic polymers for finely-tuned control of the paper process. Electrokinetic sonic amplitude (ESA) is a method for measuring particle charge and size, which has been employed in the semiconductor industry for several years. While this technology is generally geared for smaller particles (micron size) instead of paper fibers (millimeter size), this project researched the idea of using ESA to measure cationic demand in a real-time setting at high pulp consistencies. Within the scope and schedule of this project, the feasibility of the ESA technology for use in an on-line instrument was inconclusive. Further engineering is required to generate a sufficient ESA signal from the paper pulp to obtain reliable and consistent measurements. Future research in this area will help to further tailor the technology for application to paper streams. The ESA technology continues to remain a viable option for on-line charge demand measurements in the papermaking process and ...
Date: August 12, 2005
Creator: Tucker, Brian J. & Good, Morris S.
Partner: UNT Libraries Government Documents Department

Photovoltaic Cz Silicon Module Improvements; Final Subcontract Report, 9 November 1995 - 8 November 1998

Description: This report describes work that focused on reducing the cost per watt of Cz silicon photovoltaic modules under Siemens Solar Industries' (SSI) DOE/NREL Photovoltaic Manufacturing Technology (PVMaT) 4A subcontract. SSI researchers deployed new module designs, realized improvements in yield of more than 25%, and implemented statistical process control (SPC). They have described yield improvements in detail and reported on the deployment of SPC in critical process steps. The sum of all improvements resulted in a greater than 17% cost per watt reduction in manufacturing.
Date: June 17, 1999
Creator: Jester, T. L.
Partner: UNT Libraries Government Documents Department

Process Control System Cyber Security Standards - An Overview

Description: The use of cyber security standards can greatly assist in the protection of process control systems by providing guidelines and requirements for the implementation of computer-controlled systems. These standards are most effective when the engineers and operators, using the standards, understand what each standard addresses. This paper provides an overview of several standards that deal with the cyber security of process measurements and control systems.
Date: May 1, 2006
Creator: Evans, Robert P.
Partner: UNT Libraries Government Documents Department

Help for the Developers of Control System Cyber Security Standards

Description: A Catalog of Control Systems Security: Recommendations for Standards Developers (Catalog), aimed at assisting organizations to facilitate the development and implementation of control system cyber security standards, has been developed. This catalog contains requirements that can help protect control systems from cyber attacks and can be applied to the Critical Infrastructures and Key Resources of the United States and other nations. The requirements contained in the catalog are a compilation of practices or various industry bodies used to increase the security of control systems from both physical and cyber attacks. They should be viewed as a collection of recommendations to be considered and judiciously employed, as appropriate, when reviewing and developing cyber security standards for control systems. The recommendations in the Catalog are intended to be broad enough to provide any industry using control systems the flexibility needed to develop sound cyber security standards specific to their individual security requirements.
Date: May 1, 2008
Creator: Evans, Robert P.
Partner: UNT Libraries Government Documents Department

Study of the State-of-the-Art of Instrumentation for Process Control and Safety in Large-Scale Coal Gasification, Liquefaction, and Fluidized-Bed Combustion Systems

Description: A study has been carried out to determine the state-of-the-art of instrumentation which is available for process control and safety in planned demonstration and commercial scale coal gasification, liquefaction, and fluidized-bed combustion systems. The study identified available instrumentation which will perform satisfactorily in these systems and pinpointed deficiencies for which instruments must be developed. The identified deficiencies fall into the same few categories for all processes considered. These categories are presented with associated physical parameters found in the various processes studied. Development of instruments to meet these deficiencies is recommended along with development of control valves and optimal control schemes in order to assure the possibility of automatic control of the large scale coal conversion and combustion systems.
Date: 1976
Creator: O'Fallon, N. M.; Beyerlein, R. A.; Managan, W. W.; Karplus, H. B. & Mulcahey, T. P.
Partner: UNT Libraries Government Documents Department

LDRD final report on enhanced edge detection techniques for manufacturing quality control and materials characterization

Description: Detecting object boundaries in the presence of cast shadows is a difficult task for machine vision systems. A new edge detector is presented which responds to shadow penumbras and abrupt object edges with distinguishable signals. The detector requires the use of spatially extended light sources and sufficient video resolution to resolve the shadow penumbras of interest. Detection of high frequency noise is suppressed without requiring image-dependent adjustment of signal thresholds. The ability of the edge operator to distinguish shadow penumbras from abrupt object boundaries while suppressing responses to high frequency noise and texture is illustrated with idealized shadow and object edge intensity profiles. Selective detection of object boundaries in a video scene with a cast shadow has also been demonstrated with this operator.
Date: January 1, 1997
Creator: Osbourn, G.C.
Partner: UNT Libraries Government Documents Department

Diffusion Resistant, High-Purity Wafer Carriers For SI Semiconductor Production

Description: The Cooperative Research and Development Agreement (CRADA) was directed towards development of diffusion resistant, high-purity wafer carriers for Si semiconductor production with improved properties compared to current materials. The determination of the infiltration behavior is important for controlling the fabrication process to obtain consistent high-quality products. Ammonium molybdate or molybdenum carbide were found to be suitable as a precursor to produce SiC-MoSi{sub 2}-Si composites by Si infiltration into carbon preforms. Experiments on the pyrolysis of the preforms showed variable infiltration behavior by the molten Si (within the range of conditions in the present study). Further research is required to reproducibly and consistently fabricate flaw-free articles. The strength of the composites fabricated to-date was 325 {+-} 124 MPa, which is higher than current commercial products. Better process control should result in higher average strengths and reduce the variability.
Date: December 5, 2000
Creator: Tiegs, T.N.
Partner: UNT Libraries Government Documents Department

Surface waviness resulting from single point diamond dressing in cylindrical grinding

Description: This paper describes an experimental investigation of workpiece surface waviness that stems from poor single point diamond wheel dressing procedures in cylindrical grinding. If done improperly, single point dressing can produce a thread on the grinding wheel surface that is then imposed on the workpiece during machining. The circumferential waviness exhibited by the threaded workpiece is similar to that resulting from one per rev vibrations of the grinding wheel. In order to differentiate between these two sources of waviness, a geometrical approach to predicting the circumferential and axial waves produced during grinding is presented. The concepts presented are illustrated through a series of plunge grinding tests incorporating dressing procedures of varying quality. Test results verify that dressing induced circumferential waviness is similar to waviness resulting from one per rev type vibrations of the grinding wheel. The two sources can be distinguished, however, through examination of the workpiece waviness in the axial direction.
Date: May 1, 1996
Creator: Redmond, J.; Hinnerichs, T. & Apodaca, E.
Partner: UNT Libraries Government Documents Department