A graph theoretic approach to evaluate the intensity of barriers in the implementation of total productive maintenance (TPM)

Total productive maintenance (TPM) is an innovative approach to maintenance which holds the potential for enhancing effectiveness of production facilities. But, implementation of TPM is not an easy task. Innumerable barriers are encountered in real-life cases during TPM implementation. It is very essential to evaluate the nature and impact of these barriers so that production and maintenance managers can cultivate some strategies to overcome these barriers. In the present exertion, a graph theoretic approach has been applied to find the intensity of these barriers through an index which is computed through a permanent function obtained from the digraph of TPM barriers.     

真空发生器结构参数与性能参数关系研究

简要介绍了真空发生器的工作原理及应用,探讨了真空发生器的结构参数与性能参数之间的联系.     

炭材料的性质与炭-炭粘接性能关系的研究

为实现高温条件下炭材料的有效连接，利用陶瓷组元改性酚醛树脂制备了树脂基高温粘接剂，用该粘接剂粘接了4种不同孔隙结构的炭材料，并进行400～1200℃的高温热处理，利用万能材料试验机考察了上述粘接剂的高温粘接性能，通过压汞仪分析了4种炭材料的孔隙结构及其与粘接性能间的相互关系，结果表明：粘接样品在高温热处理后仍具有较为理想的连接强度；炭材料表面的孔隙率和孔径分布对粘接强度有一定的影响；合适的孔隙率和孔径分布是实现高性能连接的必要条件。     

Relationship between downstream integration,performance measurement systems and supply network efficiency

Downstream integration is a key managerial area to improve performance in supply networks. Though most studies agree that downstream integration positively influences performances, the literature also reports cases of failures in achieving significant improvements. This evidence suggests that some factors may act as moderators on the downstream integration-performance relationship. This paper analyses the impact of downstream integration on supply network efficiency and the moderating effect on this relationship of supply network performance measurement systems. Data from a sample of 200 manufacturing plants settled in several countries around the world demonstrate that this moderating effect exists. Therefore, in order to strengthen the impact of downstream integration on supply network efficiency, managers should combine interventions on downstream integration and supply network performance measurement systems, rather than investing and focusing on downstream integration only.     

Relationship between mechanical performance and microstructure in composites fabricated with flow-enhancing fabrics

The resin transfer moulding process involves the long-range flow of resin into a closed mould which is filled with dry reinforcement. High-performance composites require a high volume fraction of fibres, which results in low porosity of the fibre pack and therefore slow rates of mould filling. Commercial reinforcement fabrics are becoming available which promote faster resin flow than conventional fabrics, by engineering regions of large pore space into the reinforcement stack. However, theoretical models of the property-microstructure relationships have indicated that resin-rich areas (corresponding to filled large pore space) and fibre clustering will lead to degradation of the mechanical performance of the laminate. This report describes a series of compression and interlaminar shear tests on a range of twill-weave fabrics having ‘flow-enhancing’ tows substituted in the warp direction. The results provide some experimental support for existing theoretical models.     

Relationship between Geriatric Nutritional Risk Index and total lymphocyte count and mortality of hemodialysis patients

We examined the relationships between Geriatric Nutritional Risk Index (GNRI), total lymphocyte count (TLC), and mortality in hemodialysis (HD) patients. We examined GNRI and TLC in 120 maintenance HD patients and followed these patients for 120 months. Predictors of all‐cause death were examined using life table analysis and the Cox proportional hazards model. TLC marginally correlated with GNRI (r = 0.176; p = 0.090) and significantly with phosphorus levels (r = 0.206; p = 0.026). Life table analysis revealed that subjects with a GNRI < 90 (n = 19) had lower survival rates than did those with a GNRI ≥ 90 (n = 101; Wilcoxon's test, p = 0.048), but subjects with a TLC < 1500/mm³ (n = 76) had similar survival rates compared with subjects with a TLC ≥ 1500/mm³ (n = 44; Wilcoxon's test, p = 0.500). Multivariate Cox proportional hazards analyses demonstrated that GNRI is a significant predictor of mortality (hazard ratio 9.315, 95% confidence interval 1.161–74.753, p = 0.036), after adjusting for age, sex, presence of type 2 diabetes mellitus, Kt/V, normalized protein catabolic rate, hematocrit, phosphorus, systolic blood pressure and TLC. Our findings suggest the TLC may be used as a simple nutritional tool, but may not be a predictor of mortality in HD patients. These findings require confirmation by further studies.     

Cobalt-based orthopaedic alloys: Relationship between forming route,microstructure and tribological performance

The average longevity of hip replacement devices is approximately 10–15 years, which generally depends on many factors. But for younger generation patients this would mean that revisions may be required at some stage in order to maintain functional activity. Therefore, research is required to increase the longevity to around 25–30 years; a target that was initially set by John Charnley. The main issues related to metal-on-metal (MoM) hip replacement devices are the high wear rates when malpositioned and the release of metallic ions into the blood stream and surrounding tissues. Work is required to reduce the wear rates and limit the amount of metallic ions being leached out of the current MoM materials, to be able to produce an ideal hip replacement material. The most commonly used MoM material is the cobalt-based alloys, more specifically ASTM F75, due to their excellent wear and corrosion resistance. They are either fabricated using the cast or wrought method, however powder processing of these alloys has been shown to improve the properties. One powder processing technique used is spark plasma sintering, which utilises electric current Joule heating to produce high heating rates to sinter powders to form an alloy. Two conventionally manufactured alloys (ASTM F75 and ASTM F1537) and a spark plasma sintered (SPS) alloy were evaluated for their microstructure, hardness, tribological performance and the release of metallic content. The SPS alloy with oxides and not carbides in its microstructure had the higher hardness, which resulted in the lowest wear and friction coefficient, with lower amounts of chromium and molybdenum detected from the wear debris compared to the ASTM F75 and ASTM F1537. In addition the wear debris size and size distribution of the SPS alloy generated were considerably small, indicating a material that exhibits excellent performance and more favourable compared to the current conventional cobalt based alloys used in orthopaedics.     

The mediator role of learning capability and business innovativeness between total quality management and financial performance

The concept of total quality management (TQM) has attracted many researchers from a variety of disciplines. In particular, the literature has addressed the impact of TQM on a firm’s operations and performance. However, disparate perspectives on the relationship between TQM and a firm’s financial performance have emerged. In this paper, we suggest an interconnected relationship among TQM, organisational learning capability (OLC), business innovativeness, and a firm’s financial performance and propose that OLC and business innovativeness mediate the relationship between TQM and a firm’s financial performance. By studying 193 firms in Turkey, we found that: (1) TQM affects OLC and a firm’s business innovativeness, (2) OLC influences a firm’s business innovativeness and (3) a firm’s business innovativeness affects its financial performance. Also, we found that OLC and business innovativeness in a firm mediate the relationship between TQM and the firm’s financial performance.     

Reliability-based performance simulation for optimized pavement maintenance

Roadway pavement maintenance is essential for driver safety and highway infrastructure efficiency. However, regular preventive maintenance and rehabilitation (M&R) activities are extremely costly. Unfortunately, the funds available for the M&R of highway pavement are often given lower priority compared to other national development policies, therefore, available funds must be allocated wisely. Maintenance strategies are typically implemented by optimizing only the cost whilst the reliability of facility performance is neglected. This study proposes a novel algorithm using multi-objective particle swarm optimization (MOPSO) technique to evaluate the cost-reliability tradeoff in a flexible maintenance strategy based on non-dominant solutions. Moreover, a probabilistic model for regression parameters is employed to assess reliability-based performance. A numerical example of a highway pavement project is illustrated to demonstrate the efficacy of the proposed MOPSO algorithms. The analytical results show that the proposed approach can help decision makers to optimize roadway maintenance plans.     

Analysis and prediction of total hip replacement performance

The survival of total hip replacement in patients operated on at the Royal National Orthopaedic Hospital was analysed for two types of Stanmore prostheses: (a) metal-on-metal prostheses of various development designs inserted between 1963–72 (173), and (b) metal-on-plastic prostheses of one design inserted between 1969–72 (248). The survival criterion was taken to be non-removal of the prosthesis and all cases not removed were regarded as survivors. The results indicated that for metal-on-metal prostheses the overall probability of survival was only 53% after 11 years and the average annual probability of removal irrespective of cause was 5.5%. As expected, for metal-on-plastic prostheses the results were considerably better, the figures being 88% after eight years and 1.5% respectively. For both prosthesis types the predominant failure mode was loosening and for this failure mode the annual rate of removal increased as the follow-up time increased, suggesting that loosening is a wearing-out process. Femoral component fracture occurred less frequently, but also appeared to be a wearing-out process. Finally, it is demonstrated how the analysis can be used to predict the probability of survival at some time in the future.     

Integration of SPC and performance maintenance for supply chain system

In this paper, a supply chain system is viewed as a maintainable system, and the economic-statistical design of a likelihood ratio control chart with a maintenance application is considered for this system. The supply chain system is described by a three-state: normal state, warning state and failure state. A likelihood ratio control chart is used to monitor the system given that only categorical observations can be obtained. When the chart signals, a full inspection is performed to determine the actual system state (normal or warning), and preventive maintenance is immediately performed in the warning state. In addition, the supply chain system must be corrected upon failure (i.e. corrective maintenance), and should be maintained in a scheduled time (i.e. planned maintenance). A mathematical model is developed for the joint optimisation of the control chart parameters and planned maintenance time based on renewal theory. An example is presented to illustrate how to determine the optimal design parameters. We also investigate the effect of coefficients and statistical constraints on the decision variables and the expected cost.     

Comparative evaluation of maintenance performance using subsurvival functions

Subsurvival functions are applied to operational data for the control rod drive systems of Nordic nuclear reactors to evaluate maintenance performance. Competing failure modes are preventive and corrective maintenance. Maintenance indicators are defined and evaluated for 8 plants.     

The use of maintenance indicators to evaluate the effects of maintenance programs on NPP performance and safety

Nuclear Power Plants (NPPs) under commercial operation are under continuous demand to meet higher levels of performance and safety by NPP owners, regulatory authorities and the public in general. Maintenance plays an important role in achieving such a goal, therefore, many programs are being conducted in order to improve their effectiveness. A common link between these programs is the necessity to evaluate how maintenance affects NPP performance and safety. This paper presents the foundation of a methodology for a maintenance evaluation program based on maintenance indicators and how it is applied to monitoring the effectiveness of the maintenance at the Cofrentes NPP. The methodology is general and might be applied in other fields of industrial engineering, particularly in those activities which devote many resources to maintain plant equipment, and also in those with less but very critical maintenance.     

Optimizing the compatibility between rating scales and measures of productive second language competence

This study presents a systematic investigation concerning the performance of different rating scales used in the English section of a university entrance examination to assess 1,287 Japanese test takers' ability to write a third-person introduction speech. Although the rating scales did not conform to all of the expectations of the Rasch model, they successfully defined a meaningful continuum of English communicative competence. In some cases, the expectations of the Rasch model needed to be weighed against the specific assessment needs of the university entrance examination. This investigation also found that the degree of compatibility between the number of points allotted to the different rating scales and the various requirements of an introduction speech played a considerable role in determining the extent to which the different rating scales conformed to the expectations of the Rasch model. Compatibility thus becomes an important factor to consider for optimal rating scale performance.     

Empirical analysis of maintenance performance measurement in Belgian industries

Performance measurement is a fundamental instrument of management. For maintenance management, one of the key issues is to ensure the maintenance activities planned and executed have given the expected results. This can be facilitated by effective use of rigorously defined key performance indicators (KPI) that are able to measure important aspects of maintenance function. In this paper, an industrial survey was carried out to explore the use of performance measurement in maintenance management. Based on survey responses, analyses were performed on popularly used KPI, how these KPI are sourced or chosen; the influence of manufacturing environment and maintenance objectives on KPI choice and effective use of these KPI in decision support and performance improvement. It was found that maintenance performance measurement is dominated by lagging indicators (equipment, maintenance cost and safety performance). There is lesser use of leading (maintenance work process) indicators. The results showed no direct correlations between the maintenance objectives pursued and the KPI used. Further analysis showed that only a minority of the companies have a high percentage of decisions and changes triggered by KPI use and only a few are satisfied with their performance measurement systems. Correlation analysis showed a strong positive linear relationship between degree of satisfaction and process changes/decisions triggered by KPI use, with the least satisfied people having the least decisions and changes triggered by KPI use. The results indicate some ineffectiveness of performance measurement systems in driving performance improvement in industries.     

The impact of quality management orientation on maintenance performance

This paper aims to examine the relationship between quality management orientation dimensions and maintenance performance. The concept of quality management orientation is proposed and defined as a set of norms and values regarding customer orientation, quality responsibility, prevention and process orientation. Empirical data were drawn from a sample of Slovenian organisations in order to address the research question. The data were analysed using exploratory factor analysis, confirmatory factor analysis, correlation analysis and regression analysis. The findings indicate that quality management orientation is important predictor of maintenance performance. Data analysis results also show that quality management orientation dimensions are positively related to maintenance performance. By testing the impact of quality management orientation on maintenance performance, this study shows that strong foundation on quality management orientation is an effective way of improving maintenance performance.     

Relationship between employee involvement and lean manufacturing and its effect on performance in a rigid continuous process industry

This research aims to empirically test the effect of employee involvement on lean manufacturing (LM), and the effect of LM on production outcomes. Employee involvement is operationalised through four related variables: empowerment, training, contingent remuneration and communication. The effects are tested by recording management perceptions in a different industrial sector from those usually studied in previous research – ceramic manufacturers, a highly competitive and internationally successful sector. We obtained data from 101 ceramic tile plants (64% of response rate) in the Valencia region of Spain. This approach is developed using a statistical method called partial least squares. All paths are significant except for contingent remuneration; specifically, relationships were found between empowerment, training, communication and LM, and between LM and performance.     

Field performance of hand-mixed and machine-mixed asphalt in labour-based asphalt maintenance works

Asphalt premix for labour-based maintenance works can be produced manually (hand-mixed) or by mechanised asphalt plants – the conventional method. Hand-mixed asphalt (HDMA), common especially in most developing countries, is claimed to equal machine-mixed asphalt (MMA) in terms of durability. Recently, however, there have been concerns about reduced durability of labour-based asphalt (LBA) works. The current study compared durability of HDMA and MMA with a view to establish suitable scope and appropriate traffic conditions for LBA maintenance works. The study was based on laboratory tests – on binder, aggregate and site premix – and field experiments which involved asphalt production and placement of small and big patches of HDMA and MMA on a heavily trafficked Likuni Road and a lightly trafficked Tsiranana Avenue in Lilongwe, Malawi. The study monitored the patch durability for two months after the maintenance work. Effects of the study variables – production method (HDMA and MMA), scope of works (small and big patches) and road category (heavily trafficked and lightly trafficked roads) – on patch durability were statistically analysed. The study has shown that production method affects durability of LBA the most. HDMA had 67% less durability than MMA. Scope of works and road class affected LBA durability by 27% and 23%, respectively. At a level of significance (p-value) of 0.05, the effect of production method was significant, while that of patch size and work scope was not statistically significant. It is imperative of asphalt producers to adhere to proportions of premix components if quality of HDMA is to improve. Apart from improving the HDMA production process, the quality of LBA works could be improved by increasing contractors’ access to MMA. The study recommends contractors’ cooperation and adoption of production techniques (cost-cutting techniques) such as use of recycled asphalt pavement and warm mixture asphalts in order to improve contractors’ access to MMA.     

Concepts for measuring maintenance performance and methods for analysing competing failure modes

Measurement of maintenance performance is done on the basis of component history data in which service sojourns are distinguished according to whether they terminate in corrective or preventive maintenance. From the viewpoint of data analysis, corrective and preventive maintenance constitute competing failure nudes. This article examines ways to assess maintenance performance without introducing statistical assumptions, then introduces a plausible statistical model for describing the interaction of preventive and corrective maintenance, and finally illustrates these with examples from the Nordic TUD data system.