ISSN:0748-8017    

DOI:10.1002/qre.4680110102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo previous studies of the application of the techniques of information technology and statistics to the relatively low‐level records of a semi‐automated iron foundry have been made. Each has contributed to better knowledge and understanding of variables of the casting process, in the course of solving a specific problem. Encouraged by the enthusiasm for and quality of record keeping evident during the studies, it was decided to use the same investigative approach to make a deliberate search for any opportunity that might exist for improving the quality and/or productivity of green sand moulding.Data collected over a period of ten weeks were analysed under four broad headings: products, input materials, process operations and control of process variables. A comparison of production figures from the start and finish of the datum period revealed a reduction in the mould rejection rate of 40 per cent with reductions in inputs of new sand and bentonite of 42 and 12 per cent, respectively. The seemingly onerous task of good process record keeping had proved to present an opportunity in disgu

ISSN:0748-8017    

DOI:10.1002/qre.4680110103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA flexible, generically applicable and inexpensive data acquisition system (DAS), for machine tool condition monitoring, has been designed, constructed and installed as part of a European Union sponsored project. The DAS is more than just a data logger and an array of sensors. It also consists of a methodology for analysing data logging requirements and a relational database that supports this methodology. The database is held on a central ‘maintenance management’ computer. The monitoring to be carried out by the DAS is specified through this database, which contains detailed information about the DAS's facilities. This feature makes it simple to reconfigure the DAS to implement new monitoring requirements and to customize its operation to meet the needs of different machines. The information in the database is transformed into a look‐up table that is read by the software that sets up and controls the data logging proc

ISSN:0748-8017    

DOI:10.1002/qre.4680110104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA simple one‐dimensional thermal model of the electromigration phenomenon shows that the usual measurement methods of the temperature during lifetime tests usually lead to an erroneous determination of Black's relation parametersnandQ. The effects of the current density and the temperature estimation method on the errors onnandQare analysed. An estimation of the temperature of the site where the flux divergence is maximum allows us to understand the behaviour ofnandQ. The difference between real and apparent activation energy, at low current densities, is also calculate

ISSN:0748-8017    

DOI:10.1002/qre.4680110105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe applicability of NIST‐ASTM electromigration test patterns when used to test ‘bamboo’ metal lines is discussed. Wafer level tests on passivated and non‐passivated samples employing the Al–1%Si/TiN/Ti metallization scheme were performed. Straight metal lines 1000 μm long and 0·9 μm or 1·4 μm wide were tested at two different current densities.j= 3 MA cm2andj= 4·5 MA/cm2, at constant stress temperature (T= 230·C). The failures mainly occurred in the end‐segment areas and hindered the evaluation of the electromigration resistance of the ‘bamboo’ test lines. In order to avoid this problems, completely different test patterns based on different appro

ISSN:0748-8017    

DOI:10.1002/qre.4680110106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo separate reliability models are proposed which one may wish to use to assess product performance. By combining stresses associated with traditional high temperature tests, temperature cycling tests and power cycling tests, we believe more representative and comprehensive reliability tests can be created. Although this understandably makes the models employed slightly more complex, the introduction of a step‐stress methodology compensates for this, thereby eliminating the requirement for additional test cells to determine the particular model's parameters. Estimates for the model parameters, or their associated acceleration factors relative to the normal use environment, will enable us to make accurate reliability prediction

ISSN:0748-8017    

DOI:10.1002/qre.4680110107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe failure patterns of a well‐known brand of a hydraulic excavator system used in different environments were modelled adequately with an NHPP (non‐homogeneous Poisson process) having time‐dependent log‐linear peril rate functions. Using the fitted model, the reliability of the excavator system was estimated in different environments (cement plant, coal mine, iron ore mine, etc.). The system reliability was found to be very poor during the initial phase of operation and gradually improved with an increase in cumulative operating hours regardless of change in environment. Notwithstanding this general trend, the system reliability differed significantly in different environments for any given duration of operation and was particularly very poor in cement plants. With the help of the FMEA technique, high risk prone failure modes of the excavator system of the given model were identified and appropriate corrective measures were initiated. The failure patterns of the modified excavator system changed regardless of environment, so much so that an HPP (homogeneous Poisson process) model with constant peril rate could be fitted adequately to characterize the failure pattern of the system. The system reliability improved considerably in the initial phase of operation since s

ISSN:0748-8017    

DOI:10.1002/qre.4680110108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0748-8017    

DOI:10.1002/qre.4680110109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0748-8017    

DOI:10.1002/qre.4680110110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0748-8017    

DOI:10.1002/qre.4680110111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY