Showing papers on "Acceptance testing published in 1969"

Quality assurance in highway construction: part iv - variations of bituminous construction

Abstract: PROGRESS IS REVIEWED IN THE BUREAU OF PUBLIC ROADS RESEARCH PROGRAM FOR THE STATISTICAL APPROACH TO QUALITY ASSURANCE IN HIGHWAY CONSTRUCTION. TO DETERMINE THE QUALITY CHARACTERISTICS OF CURRENT CONSTRUCTION, MANY STATES HAVE BEEN MEASURING VARIATIONS IN ACCEPTED BITUMINOUS PRODUCTION. IT HAS BEEN FOUND THAT THE PRODUCTION OF HIGHWAY QUALITY BITUMINOUS PAVEMENT REQUIRES THE DILIGENCE OF THE PRODUCER, THE CONTRACTOR AND THE CONTRACTING AGENCY. THE STATISTICALLY MEASURED VARIATIONS OF ACCEPTED CONSTRUCTION INDICATE THAT MUCH MORE VARIABILITY EXISTS THAN IS REVEALED BY THE USUAL ACCEPTANCE TESTS. VARIATIONS IN EXCESS OF THOSE NORMALLY EXPECTED FOR GOOD PRACTICE WERE PREVALENT ON ALMOST EVERY JOB STUDIED. LARGE SAMPLING AND TESTING ERRORS VIRTUALLY PREVENT A TRUE EVALUATION OF THE MATERIAL VARIATION ON A SPECIFIC JOB. IT IS DIFFICULT TO ASSESS THE DEGREE TO WHICH VARIATIONS AFFECT ACTUAL PAVEMENT PERFORMANCE. RESEARCH RESULTS INDICATE THAT MUCH IMPROVEMENT COULD BE OBTAINED AND TESTING LOAD REDUCED BY THE FOLLOWING CHANGES: (1) ADJUST TOLERANCE LIMITS ON GRADATION TO CONFORM TO THE PRINCIPLE OF MOST TOLERANCE ON LARGEST FRACTION RETAINED ON A SIEVE, (2) CONTROL THE UNIFORMITY OF GRADATION OF THE MIXTURE BY HOT BIN SIEVE TESTS, WHEN A PRINTED RECORD OF BATCH WEIGHTS IS AVAILABLE, (3) REDUCE TO A MINIMUM THE NUMBER OF SIEVES USED FOR CONTROL TESTING, (4) EXERCISE MORE DILIGENCE IN THE TRAINING AND SURVEILLANCE OF OPERATORS PERFORMING CONTROL AND ACCEPTANCE TESTS, (5) REQUIRE INSTALLATION OF AUTOMATIC FEATURES ON ASPHALT PLANTS AND FINISHERS TO REDUCE HUMAN ERROR, AND (6) USE RANDOM SAMPLING TO OBTAIN ALL TEST PORTIONS.

Centralized large-scale clinical testing in a commercial environment

Abstract: This article will deal with the role of the large medical testing laboratory, and its increasing importance to the medical community. It will illustrate the necessary interrelationship of technological advances in instrumentation, transportation, and communication. The role of the computer with supporting electronic and electrical systems in handling a large volume of clinical test data will be outlined. From a scientific and economic standpoint, it will demonstrate the merits of volume testing in the areas of quality control, speed, and cost per test. Good business practices and the importance of continuing research, continuing education, continuing growth as adjuncts of the large clinical testing laboratory will be noted. It will show the ability of the large medical testing laboratory, with private capitalization, vision and sound management to keep pace with the demands of physicians for test data for patient diagnosis, evaluation and treatment, today and in the future.

Measurement standards for integrated circuit processing

Abstract: Both yield and quality of silicon monolithic integrated circuits depend on adequate control at all stages of their manufacture. Such control depends on measurement at each step, beginning with the selection of the substrate wafer, process chemicals, and parts, through the fabrication, assembly, and packaging of the finished circuit. The American Society for Testing and Materials Committee F-1 has developed standards for tests which have been widely used in the exchange of materials at various interfaces in the electron device industry. Many of these can be readily adapted for in-process control as well as for materials and parts acceptance tests. These standards and the process by which they were developed are reviewed; the importance of both industrial participation and the technical support activities of the National Bureau of Standards in this development is indicated. The need for additional standards is emphasized.

Statistical study of the compliance with specification of concrete supplied for highway structures in the united kingdom

Abstract: A STUDY HAS BEEN MADE OF THE STATISTICAL IMPLICATIONS OF A UNITED KINGDOM SPECIFICATION FOR STRENGTH OF CONCRETE FOR HIGHWAY STRUCTURES AND THE QUALITY OF MATERIALS SUPPLIED TO AND ACCEPTED UNDER THE SPECIFICATION TO SEE IN WHAT WAY THE SPECIFICATION MIGHT BE IMPROVED. THE DISTRIBUTION OF RESULTS FROM STRENGTH TESTS IS NORMAL AND THE PROPORTION OF CONCRETE DEFECTIVE AT ANY SPECIFIED STRENGTH MAY BE ESTIMATED ONCE THE STATISTICAL PARAMETERS OF THE DISTRIBUTION HAVE BEEN EVALUATED. THE PROPORTION DEFECTIVE PROVIDES A USEFUL MEASURE OF EQUALITY THAT CAN BE USED TO STUDY THE EFFECT OF PARTICULAR SPECIFICATION REQUIREMENTS ON THE QUALITY OF CONCRETE SUPPLIED IF THE OPERATING CHARACTERISTIC (OC) CURVE (RELATING THE PROPORTION DEFECTIVE AND THE PROBABILITY OF ACCEPTANCE OF THAT QUALITY) IS COMPUTED OVER A RANGE OF QUALITIES. THE CONCLUSIONS REACHED FROM EXAMINATION OF THE OC CURVE ARE COMPARED WITH THE RESULTS OF A STATISTICAL EXAMINATION OF THE ACTUAL QUALITY OF CONCRETE SUPPLIED TO 186 JOBS WHERE 8,400 TEST RESULTS WERE OBTAINED. METHODS OF IMPROVING SPECIFICATIONS ARE BRIEFLY CONSIDERED IN THE LIGHT OF THE RISKS TO THE PRODUCER OF CONCRETE AND TO THE CONSUMER, THE OBJECT OF ANY SPECIFICATION BEING TO PROVIDE A FAIR APPORTIONMENT OF THE RISKS OF REJECTION OF 'GOOD' MATERIAL AND ACCEPTANCE OF 'POOR' MATERIAL BETWEEN PRODUCER AND CONSUMER. /AUTHOR/