Hong Kong Polytechnic University

About: Hong Kong Polytechnic University is a education organization based out in Hong Kong, China. It is known for research contribution in the topics: Tourism & Population. The organization has 29633 authors who have published 72136 publications receiving 1956312 citations. The organization is also known as: HKPU & PolyU.

Maintenance, Replacement, and Reliability: Theory and Applications

Abstract: Introduction From Maintenance Management to Physical Asset Management The Challenges of Physical Asset Management Improving Physical Asset Management Reliability through the Operator: Total Productive Maintenance Reliability by Design: Reliability-Centered Maintenance Optimizing Maintenance and Replacement Decisions The Quantitative Approach References Component Replacement Decisions Introduction Optimal Replacement Times for Equipment Whose Operating Cost Increases with Use Stochastic Preventive Replacement: Some Introductory Comments Optimal Preventive Replacement Interval of Items Subject to Breakdown (Also Known as the Group or Block Policy Optimal Preventive Replacement Age of an Item Subject to Breakdown Optimal Preventive Replacement Age of an Item Subject to Breakdown, Taking Account of the Times Required to Effect Failure and Preventive Replacements Optimal Preventive Replacement Interval or Age of an Item Subject to Breakdown: Minimization of Downtime Group Replacement: Optimal Interval between Group Replacements of Items that Are Subject to Failure: The Lamp Replacement Problem Further Replacement Models Spare Parts Provisioning: Preventive Replacement Spares Spare Parts Provisioning: Insurance Spares Solving the Constant-Interval and Age-Based Models Graphically: Use of Glasser's Graphs Solving the Constant-Interval and Age-Based Models Using the OREST Software References Problems Inspection Decisions Introduction Optimal Inspection Frequency: Maximization of Profit Optimal Inspection Frequency: Minimization of Downtime Optimal Inspection Interval to Maximize the Availability of Equipment Used in Emergency Conditions, Such as a Protective Device Optimizing Condition-Based Maintenance (CBM) Decisions References Problems Capital Equipment Replacement Decisions Introduction Optimal Replacement Interval for Capital Equipment: Minimization of Total Cost Optimal Replacement Interval for Capital Equipment: Maximization of Discounted Benefits Optimal Replacement Interval for Capital Equipment Whose Planned Utilization Pattern Is Variable: Minimization of Total Cost Optimal Replacement Policy for Capital Equipment Taking into Account Technological Improvement: Finite Planning Horizon Optimal Replacement Policy for Capital Equipment Taking into Account Technological Improvement: Infinite Planning Horizon Software for Economic Life Optimization References Problems Maintenance Resource Requirements Introduction Queuing Theory Preliminaries Optimal Number of Workshop Machines to Meet a Fluctuating Workload Optimal Mix of Two Classes of Similar Equipment (such as Medium/Large Lathes) to Meet a Fluctuating Workload Rightsizing a Fleet of Equipment: An Application Optimal Size of a Maintenance Workforce to Meet a Fluctuating Workload, Taking Account of Subcontracting Opportunities The Lease or Buy Decision References Problem Appendix 1: Statistics Primer Appendix 2: Weibull Analysis Appendix 3: Time Value of Money: Discounted Cash Flow Analysis Appendix 4: List of Applications of Maintenance Decision Optimization Models Appendix 5: Ordinates of the Standard Normal Distribution Appendix 6: Areas in the Tail of the Standard Normal Distribution Appendix 7: Values of Gamma Function Appendix 8: Median Ranks Table Appendix 9: Five Percent Ranks Table Appendix 10: Ninety-Five Percent Ranks Table Appendix 11: Critical Values for the Kolmogorov-Smirnov Statistic (d) Appendix 12: Answers to Problems Index

Determining the Level of Reflective Thinking from Students' Written Journals Using a Coding Scheme Based on the Work of Mezirow.

Abstract: To determine whether students are engaged in reflective practice it is necessary to have some means of identifying reflective thought and a measure of the depth of reflective thinking. Several measures of reflectivity have been proposed but there appears to be no widely accepted and clearly formulated procedure for determining levels of reflective thinking from students' written reflective journals. In this study we propose a scheme for estimating the quality of reflective thinking in students' writing in reflective journals, using categories based on Mezirow's work on reflective thinking. In an initial test of the scheme, reasonable levels of agreement were obtained from eight judges. Disagreements over coding resulted from differing interpretations of the significance of what students had written rather than from a lack of precision in the guidelines for coding categories. A second test, using students' reflective papers, showed acceptable levels of reliability between four assessors. The method is reco...

Digital Signal Processing for Short-Reach Optical Communications: A Review of Current Technologies and Future Trends

Abstract: Driven primarily by cloud service and data-center applications, short-reach optical communication has become a key market segment and growing research area in recent years. Short-reach systems are characterized by direct detection-based receiver configurations and other low-cost and small form factor components that induce transmission impairments unforeseen in their coherent counterparts. Innovative signaling and digital signal processing (DSP) play a pivotal role in enabling these components to realize their ultimate potentials and meet data rate requirements in cost-effective manners. This paper presents an overview of recent DSP developments for short-reach communications systems and discusses future trends.

General synthesis of two-dimensional van der Waals heterostructure arrays.

Abstract: Two-dimensional van der Waals heterostructures (vdWHs) have attracted considerable interest1–4. However, most vdWHs reported so far are created by an arduous micromechanical exfoliation and manual restacking process5, which—although versatile for proof-of-concept demonstrations6–16 and fundamental studies17–30—is clearly not scalable for practical technologies. Here we report a general synthetic strategy for two-dimensional vdWH arrays between metallic transition-metal dichalcogenides (m-TMDs) and semiconducting TMDs (s-TMDs). By selectively patterning nucleation sites on monolayer or bilayer s-TMDs, we precisely control the nucleation and growth of diverse m-TMDs with designable periodic arrangements and tunable lateral dimensions at the predesignated spatial locations, producing a series of vdWH arrays, including VSe2/WSe2, NiTe2/WSe2, CoTe2/WSe2, NbTe2/WSe2, VS2/WSe2, VSe2/MoS2 and VSe2/WS2. Systematic scanning transmission electron microscopy studies reveal nearly ideal vdW interfaces with widely tunable moire superlattices. With the atomically clean vdW interface, we further show that the m-TMDs function as highly reliable synthetic vdW contacts for the underlying WSe2 with excellent device performance and yield, delivering a high ON-current density of up to 900 microamperes per micrometre in bilayer WSe2 transistors. This general synthesis of diverse two-dimensional vdWH arrays provides a versatile material platform for exploring exotic physics and promises a scalable pathway to high-performance devices. A general strategy for the synthesis of two-dimensional van der Waals heterostructure arrays is used to produce high-performance electronic devices, showing the potential of this scalable approach for practical technologies.