Aspects of the design and operation of production control systems in manufacturing industry

Computerised production control developments have concentrated on Manufacturing Resources Planning (MRP II) systems. The literature suggests however, that despite the massive investment in hardware, software and management education, successful implementation of such systems in manufacturing industries has proved difficult. This thesis reviews the development of production planning and control systems, in particular, investigates the causes of failures in implementing MRP/MRP II systems in industrial environments and argues that the centralised and top-down planning structure, as well as the routine operational methodology of such systems, is inherently prone to failure. The thesis reviews the control benefits of cellular manufacturing systems but concludes that in more dynamic manufacturing environments, techniques such as Kanban are inappropriate. The basic shortcomings of MRP II systems are highlighted and a new enhanced operational methodology based on distributed planning and control principles is introduced. Distributed Manufacturing Resources Planning (DMRP), was developed as a capacity sensitive production planning and control solution for cellular manufacturing environments. The system utilises cell based, independently operated MRP II systems, integrated into a plant-wide control system through a Local Area Network. The potential benefits of adopting the system in industrial environments is discussed and the results of computer simulation experiments to compare the performance of the DMRP system against the conventional MRP II systems presented. DMRP methodology is shown to offer significant potential advantages which include ease of implementation, cost effectiveness, capacity sensitivity, shorter manufacturing lead times, lower working in progress levels and improved customer service.

Design and function of trilobite exoskeletons

The fossil arthropod Class Trilobita is characterised by the possession of a highly mineralised dorsal exoskeleton with an incurved marginal flange (doublure). This cuticle is usually the only part of the organism to be preserved. Despite the common occurrence of trilobites in Palaeozoic sediments, the original exoskeletal mineralogy has not been determined previously. Petrographic data involving over seventy trilobite species, ranging in age from Cambrian to Devonian, together with atomic absorption and stable isotope analyses, indicate a primary low-magnesian calcite composition. Trilobite cuticles exhibit a variety of preservational textures which are related to the different diagenetic realms through which they have passed. A greater knowledge of post-depositional processes and the specific features they produce, has enabled post-mortem artefacts to be distinguished from primary cuticular microstructures. Alterations of the cuticle can either enhance or destroy primary features, and their effects are best observed in thin-sections, both under transmitted light and cathodoluminescence. Well-preserved trilobites often retain primary microstructures such as laminations, canals, and tubercles. These have been examined in stained thin-sections and by scanning electron microscopy, from as wide a range of trilobites as possible. Construction of sensory field maps has shown that although the basic organisation of the exoskeleton is the same in all trilobites, the types of microstructures found, and their distribution is species-specific. The composition, microstructure, and architecture of the trilobite exoskeleton have also been studied from a biomechanical viewpoint. Total cuticle thickness, and the relative proportions of the different layers, together with the overall architecture all affected the mechanical properties of the exoskeleton.

Evaluation and development of drainage and pipeline construction processes

In 1974 Dr D M Bramwell published his research work at the University of Aston a part of which was the establishment of an elemental work study data base covering drainage construction. The Transport and Road Research Laboratory decided to, extend that work as part of their continuing research programme into the design and construction of buried pipelines by placing a research contract with Bryant Construction. This research may be considered under two broad categories. In the first, site studies were undertaken to validate and extend the data base. The studies showed good agreement with the existing data with the exception of the excavation trench shoring and pipelaying data which was amended to incorporate new construction plant and methods. An inter-active on-line computer system for drainage estimating was developed. This system stores the elemental data, synthesizes the standard time of each drainage operation and is used to determine the required resources and construction method of the total drainage activity. The remainder of the research was into the general topic of construction efficiency. An on-line command driven computer system was produced. This system uses a stochastic simulation technique, based on distributions of site efficiency measurements to evaluate the effects of varying performance levels. The analysis of this performance data quantities the variability inherent in construction and demonstrates how some of this variability can be reconciled by considering the characteristics of a contract. A long term trend of decreasing efficiency with contract duration was also identified. The results obtained from the simulation suite were compared to site records collected from current contracts. This showed that this approach will give comparable answers, but these are greatly affected by the site performance parameters.

Measurements design and phenomena discrimination

The construction of measurements suitable for discriminating signal components produced by phenomena of different types is considered. The required measurements should be capable of cancelling out those signal components which are to be ignored when focusing on a phenomenon of interest. Under the hypothesis that the subspaces hosting the signal components produced by each phenomenon are complementary, their discrimination is accomplished by measurements giving rise to the appropriate oblique projector operator. The subspace onto which the operator should project is selected by nonlinear techniques in line with adaptive pursuit strategies.

Modular system design and control for flexible assembly

Flexible Assembly Systems (FASs) are normally associated with the automatic, or robotic, assembly of products, supported by automated material handling systems. However, manual assembly operations are still prevalent within many industries, where the complexity and variety of products prohibit the development of suitable automated assembly equipment. This article presents a generic model for incorporating flexibility into the design and control of assembly operations concerned with high variety/low volume manufacture, drawing on the principles for Flexible Manufacturing Systems (FMS) and Just-in-Time (JIT) delivery. It is based on work being undertaken in an electronics company where the assembly operations have been overhauled and restructured in response to a need for greater flexibility, shorter cycle times and reduced inventory levels. The principles employed are in themselves not original. However, the way they have been combined and tailored has created a total manufacturing control system which represents a new concept for responding to demands placed on market driven firms operating in an uncertain environment.

Extreme weather events and construction SMEs:vulnerability, impacts and responses

Purpose ��� The UK experienced a number of Extreme Weather Events (EWEs) during recent years and a significant number of businesses were affected as a result. With the intensity and frequency of weather extremes predicted in the future, enhancing the resilience of businesses, especially of Small and Medium-sized Enterprises (SMEs), who are considered as highly vulnerable, has become a necessity. However, little research has been undertaken on how construction SMEs respond to the risk of EWEs. In seeking to help address this dearth of research, this investigation sought to identify how construction SMEs were being affected by EWEs and the coping strategies being used. Design/methodology/approach ��� A mixed methods research design was adopted to elicit information from construction SMEs, involving a questionnaire survey and case study approach. Findings ��� Results indicate a lack of coping strategies among the construction SMEs studied. Where the coping strategies have been implemented, these were found to be extensions of their existing risk management strategies rather than radical measures specifically addressing EWEs. Research limitations/implications ��� The exploratory survey focused on the Greater London area and was limited to a relatively small sample size. This limitation is overcome by conducting detailed case studies utilising two SMEs whose projects were located in EWE prone localities. The mixed method research design adopted benefits the research by presenting more robust findings. Practical implications ��� A better way of integrating the potential of EWEs into the initial project planning stage is required by the SMEs. This could possibly be achieved through a better risk assessment model supported by better EWE prediction data. Originality/value ��� The paper provides an original contribution towards the overarching agenda of resilience of SMEs and policy making in the area of EWE risk management. It informs both policy makers and practitioners on issues of planning and preparedness against EWEs.

The construction and optimization of an ion mobility spectrometer for the analysis of explosives and drugs

Today, over 15,000 Ion Mobility Spectrometry (IMS) analyzers are employed at worldwide security checkpoints to detect explosives and illicit drugs. Current portal IMS instruments and other electronic nose technologies detect explosives and drugs by analyzing samples containing the headspace air and loose particles residing on a surface. Canines can outperform these systems at sampling and detecting the low vapor pressure explosives and drugs, such as RDX, PETN, cocaine, and MDMA, because these biological detectors target the volatile signature compounds available in the headspace rather than the non-volatile parent compounds of explosives and drugs.^ In this dissertation research volatile signature compounds available in the headspace over explosive and drug samples were detected using SPME as a headspace sampling tool coupled to an IMS analyzer. A Genetic Algorithm (GA) technique was developed to optimize the operating conditions of a commercial IMS (GE Itemizer 2), leading to the successful detection of plastic explosives (Detasheet, Semtex H, and C-4) and illicit drugs (cocaine, MDMA, and marijuana). Short sampling times (between 10 sec to 5 min) were adequate to extract and preconcentrate sufficient analytes (> 20 ng) representing the volatile signatures in the headspace of a 15 mL glass vial or a quart-sized can containing ��� 1 g of the bulk explosive or drug.^ Furthermore, a research grade IMS with flexibility for changing operating conditions and physical configurations was designed and fabricated to accommodate future research into different analytes or physical configurations. The design and construction of the FIU-IMS were facilitated by computer modeling and simulation of ion���s behavior within an IMS. The simulation method developed uses SIMION/SDS and was evaluated with experimental data collected using a commercial IMS (PCP Phemto Chem 110). The FIU-IMS instrument has comparable performance to the GE Itemizer 2 (average resolving power of 14, resolution of 3 between two drugs and two explosives, and LODs range from 0.7 to 9 ng). ^ The results from this dissertation further advance the concept of targeting volatile components to presumptively detect the presence of concealed bulk explosives and drugs by SPME-IMS, and the new FIU-IMS provides a flexible platform for future IMS research projects.^

Time, Cost, and Environmental Impact Analysis for Sustainable Design at Multiple Building Levels

Construction projects are complex endeavors that require the involvement of different professional disciplines in order to meet various project objectives that are often conflicting. The level of complexity and the multi-objective nature of construction projects lend themselves to collaborative design and construction such as integrated project delivery (IPD), in which relevant disciplines work together during project conception, design and construction. Traditionally, the main objectives of construction projects have been to build in the least amount of time with the lowest cost possible, thus the inherent and well-established relationship between cost and time has been the focus of many studies. The importance of being able to effectively model relationships among multiple objectives in building construction has been emphasized in a wide range of research. In general, the trade-off relationship between time and cost is well understood and there is ample research on the subject. However, despite sustainable building designs, relationships between time and environmental impact, as well as cost and environmental impact, have not been fully investigated. The objectives of this research were mainly to analyze and identify relationships of time, cost, and environmental impact, in terms of CO2 emissions, at different levels of a building: material level, component level, and building level, at the pre-use phase, including manufacturing and construction, and the relationships of life cycle cost and life cycle CO2 emissions at the usage phase. Additionally, this research aimed to develop a robust simulation-based multi-objective decision-support tool, called SimulEICon, which took construction data uncertainty into account, and was capable of incorporating life cycle assessment information to the decision-making process. The findings of this research supported the trade-off relationship between time and cost at different building levels. Moreover, the time and CO2 emissions relationship presented trade-off behavior at the pre-use phase. The results of the relationship between cost and CO2 emissions were interestingly proportional at the pre-use phase. The same pattern continually presented after the construction to the usage phase. Understanding the relationships between those objectives is a key in successfully planning and designing environmentally sustainable construction projects.

The Construction and Optimization on an Ion Mobility Spectrometer for the Analysis of Explosives and Drugs

Today, over 15,000 Ion Mobility Spectrometry (IMS) analyzers are employed at worldwide security checkpoints to detect explosives and illicit drugs. Current portal IMS instruments and other electronic nose technologies detect explosives and drugs by analyzing samples containing the headspace air and loose particles residing on a surface. Canines can outperform these systems at sampling and detecting the low vapor pressure explosives and drugs, such as RDX, PETN, cocaine, and MDMA, because these biological detectors target the volatile signature compounds available in the headspace rather than the non-volatile parent compounds of explosives and drugs. In this dissertation research volatile signature compounds available in the headspace over explosive and drug samples were detected using SPME as a headspace sampling tool coupled to an IMS analyzer. A Genetic Algorithm (GA) technique was developed to optimize the operating conditions of a commercial IMS (GE Itemizer 2), leading to the successful detection of plastic explosives (Detasheet, Semtex H, and C-4) and illicit drugs (cocaine, MDMA, and marijuana). Short sampling times (between 10 sec to 5 min) were adequate to extract and preconcentrate sufficient analytes (> 20 ng) representing the volatile signatures in the headspace of a 15 mL glass vial or a quart-sized can containing ��� 1 g of the bulk explosive or drug. Furthermore, a research grade IMS with flexibility for changing operating conditions and physical configurations was designed and fabricated to accommodate future research into different analytes or physical configurations. The design and construction of the FIU-IMS were facilitated by computer modeling and simulation of ion���s behavior within an IMS. The simulation method developed uses SIMION/SDS and was evaluated with experimental data collected using a commercial IMS (PCP Phemto Chem 110). The FIU-IMS instrument has comparable performance to the GE Itemizer 2 (average resolving power of 14, resolution of 3 between two drugs and two explosives, and LODs range from 0.7 to 9 ng). The results from this dissertation further advance the concept of targeting volatile components to presumptively detect the presence of concealed bulk explosives and drugs by SPME-IMS, and the new FIU-IMS provides a flexible platform for future IMS research projects.

Sites of Excavation and Construction

For his first solo show in Belgium, British artist Neal White presents a range of recent and new work ��� some of them in collaboration with artist Tina O���Connell ��� that reflect his ongoing preoccupations with deep time and the spaces of art. OBJECTIF EXHIBITIONS is a not-for-profit institution devoted to the presentation of contemporary art, supported by the Flemish Community. Curated by Antony Hudek

Design and development of a diagonal-airflow batch dryer for spatial drying homogeneity

Das Verfahren der Lebensmitteltrocknung wird h��ufig angewendet, um ein Produkt f��r l��ngere Zeit haltbar zu machen. Obst und Gem��se sind aufgrund ihres hohen Wassergehalts leicht verderblich durch biochemische Vorg��nge innerhalb des Produktes, nicht sachgem����e Lagerung und unzureichende Transportm��glichkeiten. Um solche Verluste zu vermeiden wird die direkte Trocknung eingesetzt, welche die ��lteste Methode zum langfristigen haltbarmachen ist. Diese Methode ist jedoch veraltet und kann den heutigen Herausforderungen nicht gerecht werden. In der vorliegenden Arbeit wurde ein neuer Chargentrockner, mit diagonalem Luftst��mungskanal entlang der L��nge des Trocknungsraumes und ohne Leitbleche entwickelt. Neben dem unbestreitbaren Nutzen der Verwendung von Leitblechen, erh��hen diese jedoch die Konstruktionskosten und f��hren auch zu einer Erh��hung des Druckverlustes. Dadurch wird im Trocknungsprozess mehr Energie verbraucht. Um eine r��umlich gleichm����ige Trocknung ohne Leitbleche zu erreichen, wurden die Lebensmittelbeh��lter diagonal entlang der L��nge des Trockners platziert. Das vorrangige Ziel des diagonalen Kanals war, die einstr��mende, warme Luft gleichm����ig auf das gesamte Produkt auszurichten. Die Simulation des Luftstroms wurde mit ANSYS-Fluent in der ANSYS Workbench Plattform durchgef��hrt. Zwei verschiedene Geometrien der Trocknungskammer, diagonal und nicht diagonal, wurden modelliert und die Ergebnisse f��r eine gleichm����ige Luftverteilung aus dem diagonalen Luftstr��mungsdesign erhalten. Es wurde eine Reihe von Experimenten durchgef��hrt, um das Design zu bewerten. Kartoffelscheiben dienten als Trocknungsgut. Die statistischen Ergebnisse zeigen einen guten Korrelationskoeffizienten f��r die Luftstromverteilung (87,09%) zwischen dem durchschnittlich vorhergesagten und der durchschnittlichen gemessenen Str��mungsgeschwindigkeit. Um den Effekt der gleichm����igen Luftverteilung auf die Ver��nderung der Qualit��t zu bewerten, wurde die Farbe des Produktes, entlang der gesamten L��nge der Trocknungskammer kontaktfrei im on-line-Verfahren bestimmt. Zu diesem Zweck wurde eine Imaging-Box, bestehend aus Kamera und Beleuchtung entwickelt. R��umliche Unterschiede dieses Qualit��tsparameters wurden als Kriterium gew��hlt, um die gleichm����ige Trocknungsqualit��t in der Trocknungskammer zu bewerten. Entscheidend beim Lebensmittel-Chargentrockner ist sein Energieverbrauch. Daf��r wurden thermodynamische Analysen des Trockners durchgef��hrt. Die Energieeffizienz des Systems wurde unter den gew��hlten Trocknungsbedingungen mit 50,16% kalkuliert. Die durchschnittlich genutzten Energie in Form von Elektrizit��t zur Herstellung von 1kg getrockneter Kartoffeln wurde mit weniger als 16,24 MJ/kg und weniger als 4,78 MJ/kg Wasser zum verdampfen bei einer sehr hohen Temperatur von jeweils 65��C und Scheibendicken von 5mm kalkuliert. Die Energie- und Exergieanalysen f��r diagonale Chargentrockner wurden zudem mit denen anderer Chargentrockner verglichen. Die Auswahl von Trocknungstemperatur, Massenflussrate der Trocknungsluft, Trocknerkapazit��t und Heiztyp sind die wichtigen Parameter zur Bewertung der genutzten Energie von Chargentrocknern. Die Entwicklung des diagonalen Chargentrockners ist eine n��tzliche und effektive M��glichkeit um dei Trocknungshomogenit��t zu erh��hen. Das Design erlaubt es, das gesamte Produkt in der Trocknungskammer gleichm����igen Luftverh��ltnissen auszusetzen, statt die Luft von einer Horde zur n��chsten zu leiten.

Design and implementation of a non-destructive defect detection technique based on UWB-SAR imaging

In the last twenty years aerospace and automotive industries started working widely with composite materials, which are not easy to test using classic Non-Destructive Inspection (NDI) techniques. Pairwise, the development of safety regulations sets higher and higher standards for the qualification and certification of those materials. In this thesis a new concept of a Non-Destructive defect detection technique is proposed, based on Ultrawide-Band (UWB) Synthetic Aperture Radar (SAR) imaging. Similar SAR methods are yet applied either in minefield [22] and head stroke [14] detection. Moreover feasibility studies have already demonstrated the validity of defect detection by means of UWB radars [12, 13]. The system was designed using a cheap commercial off-the-shelf radar device by Novelda and several tests of the developed system have been performed both on metallic specimen (aluminum plate) and on composite coupon (carbon fiber). The obtained results confirm the feasibility of the method and highlight the good performance of the developed system considered the radar resolution. In particular, the system is capable of discerning healthy coupons from damaged ones, and correctly reconstruct the reflectivity image of the tested defects, namely a 8 x 8 mm square bulge and a 5 mm drilled holes on metal specimen and a 5 mm drilled hole on composite coupon.

Design and modeling of optical fibers for spatial division multiplexing using the orbital angular momentum of light

Les besoins toujours croissants en terme de transfert de donn��es num��riques poussent au d��veloppement de nouvelles technologies pour accro��tre la capacit�� des r��seaux, notamment en ce qui concerne les r��seaux de fibre optique. Parmi ces nouvelles technologies, le multiplexage spatial permet de multiplier la capacit�� des liens optiques actuels. Nous nous int��ressons particuli��rement �� une forme de multiplexage spatial utilisant le moment cin��tique orbital de la lumi��re comme base orthogonale pour s��parer un certain nombre de canaux. Nous pr��sentons d���abord les notions d�����lectromagn��tisme et de physique n��cessaires �� la compr��hension des d��veloppements ult��rieurs. Les ��quations de Maxwell sont d��riv��es afin d���expliquer les modes scalaires et vectoriels de la fibre optique. Nous pr��sentons ��galement d���autres propri��t��s modales, soit la coupure des modes, et les indices de groupe et de dispersion. La notion de moment cin��tique orbital est ensuite introduite, avec plus particuli��rement ses applications dans le domaine des t��l��communications. Dans une seconde partie, nous proposons la carte modale comme un outil pour aider au design des fibres optiques �� quelques modes. Nous d��veloppons la solution vectorielle des ��quations de coupure des modes pour les fibres en anneau, puis nous g��n��ralisons ces ��quations pour tous les profils de fibres �� trois couches. Enfin, nous donnons quelques exemples d���application de la carte modale. Dans la troisi��me partie, nous pr��sentons des designs de fibres pour la transmission des modes avec un moment cin��tique orbital. Les outils d��velopp��s dans la seconde partie sont utilis��s pour effectuer ces designs. Un premier design de fibre, caract��ris�� par un centre creux, est ��tudi�� et d��montr��. Puis un second design, une famille de fibres avec un profil en anneau, est ��tudi��. Des mesures d���indice effectif et d���indice de groupe sont effectu��es sur ces fibres. Les outils et les fibres d��velopp��s auront permis une meilleure compr��hension de la transmission dans la fibre optique des modes ayant un moment cin��tique orbital. Nous esp��rons que ces avancements aideront �� d��velopper prochainement des syst��mes de communications performants utilisant le multiplexage spatial.

The Design and Development of Educational Immersive Environments: From Theory to Classroom Deployment

Computer game technology is poised to make a significant impact on the way our youngsters will learn. Our youngsters are ���Digital Natives���, immersed in digital technologies, especially computer games. They expect to utilize these technologies in learning contexts. This expectation, and our response as educators, may change classroom practice and inform curriculum developments. This chapter approaches these issues ���head on���. Starting from a review of the current educational issues, an evaluation of educational theory and instructional design principles, a new theoretical approach to the construction of ���Educational Immersive Environments��� (EIEs) is proposed. Elements of this approach are applied to development of an EIE to support Literacy Education in UK Primary Schools. An evaluation of a trial within a UK Primary School is discussed. Conclusions from both the theoretical development and the evaluation suggest how future teacher-practitioners may embrace both the technology and our approach to develop their own learning resources.