Scheduling Manufacturing Systems With Work-in-Process Inventory Control: Single-Part-Type Systems

In this paper, a real-time feedback control algorithm is developed for scheduling single-part-type production lines in which there are three important classes of activities: operations, failures, and starvation or blockage. The scheduling objectives are to keep the actual production as close to the demand as possible, and to keep the level of work-in-process inventory as low as possible. By relating the starvation and blockage to the system capacity, the buffer sizes and the target buffer levels are chosen according to the demands and machine parameters. The processing time for each operation is deterministic. Failure and repair times are random. Whenever a machine fails or is starved or blocked, the scheduling system recalculates short term production rates. To begin with, we study a very simple case, a two machine and one part type system, to get insight into the buffer effects and production control policies. Using the relationship between system capacity and starvation or blockage, we find desirable buffer levels and buffer sizes. The production control policy is determined to meet the system performance requirements concerning low WIP inventory and tardiness. The results from the simple case are extended to N-machine, one-part-type systems

Identification of Moving Bottlenecks in Production Systems

Manufacturing sector have been plagued by bottlenecks from time immemorial, leading to loss of productivity and profitability, various research effort has been expended towards identifying and mitigating the effects of bottlenecks on production lines. However, traditional approaches often fail in identifying moving bottlenecks. The current data boom and giant strides made in the machine learning field proffers an alternative means of using the large volume of data generated by machines in identifying bottlenecks. In this study, a hierarchical agglomerative clustering algorithm is used in identifying potential groups of bottlenecks within a serial production line. A serial production line with five workstations and zero buffer was simulated in ARENA® with data regarding blocked, producing and starvation time extracted. The extracted data was preprocessed using Python 3.7 to obtain a matrix of ones and zeros. The resultant matrix was fed into a complete linkage hierarchical agglomerative clustering algorithm to obtain clusters containing potential bottleneck workstations. Results obtained was validated using results obtained from simulation and an Elbow plot

Network neutrality: Hong Kong's perspectives

--

An evaluation of total quality management practices on business performance of the Nigerian telecommunications sector: a case study of MTN Nigeria Limited

This study examines the effects of The Total Quality Management practices on Business Performance of the Nigerian Telecommunications Sector. A review of literatures on TQM shows that no study has been carried out on its application in the Nigerian Telecommunication sector hence the need for this research. To assess the situation One hundred and fifty (150) questionnaires were administered to customers of MTN Limited within the Lagos environ. These customers were randomly selected from five (5) different MTN customer care centres within the five divisions of Lagos State. These divisions include Epe, Ikorodu, Lagos Island, Lagos Mainland and Badagry. Thirty (30) questionnaires were administered at each centre. Fifty (50) questionnaires were also administered to employees of MTN and a total of twenty (20) questionnaires were administered to top management in the same organizations. The data collected were analyzed using descriptive statistics and regression analysis. Our finding revealed that 90.7% of the changes that occurred in employees’ satisfaction could be traced to the policy and commitment of top management. It also shows that 69.4% of the changes in customer satisfaction could be attributed to continuous training in quality. The study recommended among other things the training of telecommunications personnel on Total Quality Management practices and the adoption of alternative renewable sources of energy like solar to address their energy problems

End-to-End Simulation of 5G mmWave Networks

Due to its potential for multi-gigabit and low latency wireless links, millimeter wave (mmWave) technology is expected to play a central role in 5th generation cellular systems. While there has been considerable progress in understanding the mmWave physical layer, innovations will be required at all layers of the protocol stack, in both the access and the core network. Discrete-event network simulation is essential for end-to-end, cross-layer research and development. This paper provides a tutorial on a recently developed full-stack mmWave module integrated into the widely used open-source ns--3 simulator. The module includes a number of detailed statistical channel models as well as the ability to incorporate real measurements or ray-tracing data. The Physical (PHY) and Medium Access Control (MAC) layers are modular and highly customizable, making it easy to integrate algorithms or compare Orthogonal Frequency Division Multiplexing (OFDM) numerologies, for example. The module is interfaced with the core network of the ns--3 Long Term Evolution (LTE) module for full-stack simulations of end-to-end connectivity, and advanced architectural features, such as dual-connectivity, are also available. To facilitate the understanding of the module, and verify its correct functioning, we provide several examples that show the performance of the custom mmWave stack as well as custom congestion control algorithms designed specifically for efficient utilization of the mmWave channel.Comment: 25 pages, 16 figures, submitted to IEEE Communications Surveys and Tutorials (revised Jan. 2018

A guide for performing system safety analysis

A general guide is presented for performing system safety analyses of hardware, software, operations and human elements of an aerospace program. The guide describes a progression of activities that can be effectively applied to identify hazards to personnel and equipment during all periods of system development. The general process of performing safety analyses is described; setting forth in a logical order the information and data requirements, the analytical steps, and the results. These analyses are the technical basis of a system safety program. Although the guidance established by this document cannot replace human experience and judgement, it does provide a methodical approach to the identification of hazards and evaluation of risks to the system

"Integrated" and "Transcendent" E-government: Keys for Analyzing Organizational Structure and Governance

As e-government enters the “transformation” phase, public authorities face major challenges in terms of governance and leadership. The present article consolidates prior research related to organizational structure and governance, and provides an analytical framework intended to guide empirical enquiry and to orient action. We argue that our understanding is enhanced by distinguishing an “integration” stage and a “transcendence” stage of e-government maturity. While the former is accompanied by a profusion of inter-organizational arrangements, the latter’s distinctive feature are inter-personal networks. In order to appraise the implications of these organizational structures, we identify the main reasons behind their growing importance, analyze the ways they create value, and lay the foundations of a normative approach for the choice of governance structures