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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Autotuning of a vacuum conveyor

Nydahl, Oskar January 2015 (has links)
The modern industry is steadily facing new demands for more energy efficient solutions. These improvements can come from technological advances, using existing technology smarter or a combination of the two. Today a vacuum conveying system is manually tuned for each factory application when installed and is in most cases not handled afterwards except for maintenance reasons. This in combination with the difficulties in tuning a system to run efficiently and robustly whilst offering high capacity indicates that a large number of systems are running with non optimal settings. The aim of this thesis was therefore to explore the possibility of introducing an auto tuning property to the vacuum conveying system and investigate the possible benefits. This thesis has investigated two main components for such an autotuner, the system design and optimisation strategy. The system design is critical for allowing process control and monitoring. In the optimisation the main challenge was to robustly produce good results for a wide variety of materials. Based on this a laboratory system was developed that monitored the capacity, efficiency, gentleness and robustness performance of the conveying. This information was then used in anevolutionary optimisation algorithm based on differential evolution to find the best settings for optimal performance. The results of this thesis indicate that such a system would offer benefits bothin terms of initial tuning and run-time performance. The suggested auto tuner is adaptable to a large set of materials with varying material properties and demands on the conveying process. The time required for the laboratory rig to optimise within a region with only small deviations in performance is comparable to that of a human operator. Also with the added benefit of never having to stop the optimisation process, thus constantly improving performance and counteracting environmental changes. / Den moderna industrin möter ständigt nya krav på ökad effektivitet. Dessa förbättringar kan komma utifrån tillämpning av ny teknologi eller bättre utnyttjande av befintlig teknologi eller en kombination. Idag när en vakuum transportör installeras finjusteras den manuellt för att uppnå önskad prestanda och hanteras därefter ofta inte bortsett från underhållsarbete. Detta i kombination med svårigheten att justera ett system så att det går effektivt och robust samtidigt som en god kapacitet upprätthålls föranleder slutsatsen att många system ute i industrin inte presterar optimalt. Målet med detta examensarbete var därför att utreda möjligheten att skapa en automatisk system inställare samt utvärdera de möjliga fördelarna och nackdelarna. Arbetet har undersökt två huvudkomponenter i en sådan automatisk system inställare, system design och optimerings strategi. System design var vital för att tillåta styrning och monitorering av systemet och optimeringsstrategi för att tillförlitligt kunna prestera goda resultat trots skiftande beteende med olika material i systemet. Baserat på detta utvecklades en laboratorie-utrustning som övervakade kapacitet, effektivitet, robusthet och försiktighet i varje transportcykel. Denna information nyttjades sedan i en evolutionär algoritm baserad på differentierad evolution för att finna de optimala system-inställningarna. Arbetet indikerar att ett sådant system skulle erbjuda prestanda-fördelar både i driftsättande och kontinuerliga driften av en vakuum-transportör. Den föreslagna automatiska systeminställaren kan anpassas till en stor mängd material och skilda krav på önskat driftläge för systemet. Tiden för att optimera systemet så att de större variationerna i prestanda uppnås är jämförbar med en mänsklig operatör menkan fortlöpa över tiden och ständigt söka förbättringar på ett sätt som ej är möjligt för en mänsklig operatör.
52

Pneumatic conveying of flour mill stocks

Venkataramana P. Reddy, 1949- January 2011 (has links)
Vita. / Digitized by Kansas Correctional Industries
53

Modelling of fluidised dense-phase pneumatic conveying of powders

Mallick, Soumya Suddha. January 2009 (has links)
Thesis (Ph.D.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references: leaf 308-322.
54

Scheduling of flexible flowshops

January 1979 (has links)
K. L. Hitz. / Bibliography: leaf 71. / Research supported by NSF Grants DAR78-17826 and NSF/RANN APR76-12036.
55

Effects of Structural Uncertainty on the Dynamic Response of Nearly-Straight Pipes Conveying Fluid: Modeling and Numerical Validation

January 2017 (has links)
abstract: This investigation is focused on the consideration of structural uncertainties in nearly-straight pipes conveying fluid and on the effects of these uncertainties on the dynamic response and stability of those pipes. Of interest more specifically are the structural uncertainties which affect directly the fluid flow and its feedback on the structural response, e.g., uncertainties on/variations of the inner cross-section and curvature of the pipe. Owing to the complexity of introducing such uncertainties directly in finite element models, it is desired to proceed directly at the level of modal models by randomizing simultaneously the appropriate mass, stiffness, and damping matrices. The maximum entropy framework is adopted to carry out the stochastic modeling of these matrices with appropriate symmetry constraints guaranteeing that the nature, e.g., divergence or flutter, of the bifurcation is preserved when introducing uncertainty. To support the formulation of this stochastic ROM, a series of finite element computations are first carried out for pipes with straight centerline but inner radius varying randomly along the pipe. The results of this numerical discovery effort demonstrate that the dominant effects originate from the variations of the exit flow speed, induced by the change in inner cross-section at the pipe end, with the uncertainty on the cross-section at other locations playing a secondary role. Relying on these observations, the stochastic reduced order model is constructed to model separately the uncertainty in inner cross-section at the pipe end and at other locations. Then, the fluid related mass, damping, and stiffness matrices of this stochastic reduced order model (ROM) are all determined from a single random matrix and a random variable. The predictions from this stochastic ROM are found to closely match the corresponding results obtained with the randomized finite element model. It is finally demonstrated that this stochastic ROM can easily be extended to account for the small effects due to uncertainty in pipe curvature. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2017
56

Modelagem energética de sistema de transporte pneumático utilizando planejamento fatorial

Cecone, Eduardo Christiano January 2017 (has links)
Orientador: Prof. Dr. Douglas Alves Cassiano / Em meados da década de 1920 tornou-se comum o emprego de sistemas pneumáticos destinados à movimentação de materiais particulados sólidos. As principais limitações para estas aplicações estão relacionadas a aspectos financeiros, em especial ao elevado consumo energético destes sistemas em comparação a outras tecnologias existentes, porém, a partir dos ganhos relacionados à eficiência energética, é fortemente recomendável considerar o seu emprego como primeira opção, mesmo em aplicações tradicionalmente mecânicas. Levantamento realizado junto à base de dados Elsevier-Scopus em 2017 aplicando-se os termos Pneumatic Conveying + Design of Experiments + Energy Efficiency, objetos deste trabalho, revelou a existência de apenas dois trabalhos publicados no ano de 2012. Assim o trabalho ora apresentado foi motivado pela necessidade de otimização da eficiência energética nestes sistemas e pela oportunidade de avanço da fronteira do conhecimento acerca do assunto evidenciadas pela pesquisa bibliográfica realizada. Fundamentado em técnicas estatísticas de planejamento fatorial e metodologia de superfície de resposta, o trabalho ora apresentado objetivou o estudo da eficiência energética de um sistema alternativo de transporte pneumático, que envolve os conceitos do transporte pneumático em fase densa e em fase diluída. Definido o material empregado no estudo (Alumina), realizaram-se ensaios de caracterização para investigação do seu potencial de fluidização, construiu-se um protótipo do ejetor pressurizado, definiram-se os planejamentos experimentais de dois níveis e composto central, realizaram-se 71 testes para obtenção de dados experimentais e obtiveram-se os modelos matemáticos linear e não linear que aplicados e interpretados, resultaram na superfície de resposta. Concluiu-se que o sistema proposto é capaz de realizar transporte pneumático nas condições do estudo. Observou-se que a eficiência energética do sistema pode ser adequadamente investigada e estudada a partir da metodologia adotada. Obtiveram-se o modelo matemático e a superfície de resposta que, validados, possibilitaram a inferência da eficiência energética do sistema em função da pressão de transporte e do tempo de dosagem de material, bem como a identificação do ponto ótimo de operação respeitadas as condições de contorno do estudo. / Tese ( doutorado)- Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2017. / In the mid-1920s it became common to use pneumatic systems for the movement of solid particulates. The main limitations for these applications are related to financial aspects, in particular the high energy consumption of these systems compared to other existing technologies, but, from the gains related to energy efficiency, it is strongly recommended to consider their use as the first option, even in traditionally mechanical applications. A survey carried out with the Elsevier-Scopus database in 2017 applying the terms Pneumatic Conveying + Design of Experiments + Energy Efficiency, objects of this work, revealed the existence of only two works published in the year 2012. Thus, the work presented here was motivated by the need to optimize energy efficiency in these systems and the opportunity to advance the frontier of knowledge about the subject evidenced by the bibliographical research. Based on statistical techniques of factorial planning and response surface methodology, the present study aimed to study the energy efficiency of an alternative pneumatic transport system, which involves the concepts of pneumatic transport in dense phase and in diluted phase. After the determination of the material used in the study (Alumina), characterization tests were carried out to investigate its fluidization potential, a prototype of the pressurized ejector was built, the experimental design of two levels and the central compound were defined, 71 tests to obtain experimental data and obtained the linear and non-linear mathematical models that applied and interpreted, resulted in the response surface. It was concluded that the proposed system is capable of performing pneumatic transport under the conditions of the study. It was observed that the energy efficiency of the system can be adequately investigated and studied from the methodology adopted. The mathematical model and the response surface were obtained, which validated the inference of the energy efficiency of the system as a function of the transport pressure and the material dosing time, as well as the identification of the optimum operating point, respecting the operating conditions.
57

Solid Fuel Pneumatic Conveying and its Injection Geometry in a Pressurized Entrained Flow Gasifier

Kus, Francis January 2016 (has links)
Rising global energy demands have led to an increase in demand for clean, sustainable energy. A leading technology for reducing greenhouse gas (GHG) emission for existing coal-power infrastructure is gasification, which has sparked an interest in reactor modelling for design and performance analysis. Reduced order models (ROMs) have seen an increase in popularity for entrained flow gasifiers, as they offer a low-computational alternative to conventional computational fluid dynamic (CFD) modelling while maintaining the integrity of important operational parameters, such as carbon conversion and syngas yield. However, ROMs require more physical parameter inputs than are normally required for CFD modelling, such as the geometry of the gas-solid jet (specifically the jet half-angle). Experiments were conducted to understand the relation between the required input parameters for ROMs, such as fuel flow rate, transport gas flow rate, and jet half-angle, and develop useful correlations for ROM systems. A new configuration for pneumatic conveying was developed and tested at the pilot-scale system at NRCan CanmetENERGY. It was used to study the pneumatic conveying of pulverized fuels, specifically the influence of operating parameters such as pressure drop and gas flow rates on the fuel flow rate, and the geometry of the gas-solid fuel jet (notably the jet half-angle) injected into the gasifier. The mean fuel flow rate of pulverized fuels was shown to increase with increasing pressure drop and with decreasing gas flow rates in the fuel transfer line. The jet half-angle was shown to increase as the solid loading ratio in the jet core was decreased. Finally, the relative fuel flow variability was observed to be significantly influenced by the design of the pneumatic conveying system, with the fluctuations increasing with increasing pressure drop and with decreasing gas flow rate, similar to the mean flow rate.
58

Zalomený řetězový dopravník / Cranked chain conveyer

Komínek, Vojtěch January 2008 (has links)
Output of this diploma work is an overall project of the Cranked Chain Conveyer, arising from specification of the assignment. Project is divided into several phases, whereas first of them is composed of calculations and finding of necessary driving unit. First phase is followed by second phase, where I - regarding the engine power - dimension individual structural parts like loop chain, conveyer drive unit, stressing etc. In last phase I deal with drawing documentation of designed parts of the conveyer.
59

Modeling Flow, Melting, Solid Conveying and Global Behavior in Intermeshing Counter-Rotating Twin Screw Extruders

Jiang, Qibo 26 August 2008 (has links)
No description available.
60

Design Of The Layout Of A Manufacturing Facility With A Closed Loop Conveyor With Shortcuts Using Queueing Theory And Genetic Algorithms

Lasrado, Vernet Michael 01 January 2011 (has links)
With the ongoing technology battles and price wars in today's competitive economy, every company is looking for an advantage over its peers. A particular choice of facility layout can have a significant impact on the ability of a company to maintain lower operational expenses under uncertain economic conditions. It is known that systems with less congestion have lower operational costs. Traditionally, manufacturing facility layout problem methods aim at minimizing the total distance traveled, the material handling cost, or the time in the system (based on distance traveled at a specific speed). The proposed methodology solves the looped layout design problem for a looped layout manufacturing facility with a looped conveyor material handling system with shortcuts using a system performance metric, i.e. the work in process (WIP) on the conveyor and at the input stations to the conveyor, as a factor in the minimizing function for the facility layout optimization problem which is solved heuristically using a permutation genetic algorithm. The proposed methodology also presents the case for determining the shortcut locations across the conveyor simultaneously (while determining the layout of the stations around the loop) versus the traditional method which determines the shortcuts sequentially (after the layout of the stations has been determined). The proposed methodology also presents an analytical estimate for the work in process at the input stations to the closed looped conveyor. It is contended that the proposed methodology (using the WIP as a factor in the minimizing function for the facility layout while simultaneously solving for the shortcuts) will yield a facility layout which is less congested than a facility layout generated by the traditional methods (using the total distance traveled as a factor of the minimizing function for the facility layout while sequentially solving for the shortcuts). The proposed methodology is tested on a virtual 300mm Semiconductor Wafer Fabrication Facility with a looped conveyor material handling system with shortcuts. The results show that the facility layouts generated by the proposed methodology have significantly less congestion than facility layouts generated by traditional methods. The validation of the developed analytical estimate of the work in process at the input stations reveals that the proposed methodology works extremely well for systems with Markovian Arrival Processes.

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