• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 66
  • 22
  • 16
  • 12
  • 11
  • 8
  • 4
  • 2
  • 2
  • Tagged with
  • 170
  • 42
  • 26
  • 23
  • 16
  • 16
  • 14
  • 13
  • 12
  • 12
  • 12
  • 11
  • 11
  • 11
  • 11
  • 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.
81

Gait termination on a declined surface in trans-femoral amputees: Impact of using microprocessor-controlled limb system

Abdulhasan, Zahraa M., Scally, Andy J., Buckley, John 30 May 2018 (has links)
Yes / Walking down ramps is a demanding task for transfemoral-amputees and terminating gait on ramps is even more challenging because of the requirement to maintain a stable limb so that it can do the necessary negative mechanical work on the centre-of-mass in order to arrest (dissipate) forward/downward velocity. We determined how the use of a microprocessor-controlled limb system (simultaneous control over hydraulic resistances at ankle and knee) affected the negative mechanical work done by each limb when transfemoral-amputees terminated gait during ramp descent. Methods: Eight transfemoral-amputees completed planned gait terminations (stopping on prosthesis) on a 5-degree ramp from slow and customary walking speeds, with the limb's microprocessor active or inactive. When active the limb operated in its ‘ramp-descent’ mode and when inactive the knee and ankle devices functioned at constant default levels. Negative limb work, determined as the integral of the negative mechanical (external) limb power during the braking phase, was compared across speeds and microprocessor conditions. Findings: Negative work done by each limb increased with speed (p < 0.001), and on the prosthetic limb it was greater when the microprocessor was active compared to inactive (p = 0.004). There was no change in work done across microprocessor conditions on the intact limb (p = 0.35). Interpretation: Greater involvement of the prosthetic limb when the limb system was active indicates its ramp-descent mode effectively altered the hydraulic resistances at the ankle and knee. Findings highlight participants became more assured using their prosthetic limb to arrest centre-of-mass velocity. / ZA is funded by the Higher Committee of Education Development in IRAQ (HCED student number D13 626).
82

Mine closure : a contingency plan to mitigate socio-economic disasters / Maria Elizabeth Ackermann

Ackermann, Maria Elizabeth January 2013 (has links)
The history of the mining industry indicates a lack of understanding among the decision-makers of the impact the closure of mines has on the industry and the associated effects on the society and surrounding environment. The policies of the mining industry do make provision for a planned mine closure, but not for an unexpected closure. This detrimental aspect of closures in the mining industry is highlighted in the present study. The present study investigates how mineworkers’ dependency on their employment at a mine affects their ability to sustain their livelihoods. Vulnerable livelihoods leave the community at a greater risk to be affected by a disaster, than the livelihoods of a community that is resilient and has sustainable resources. Even though mineworkers are not considered as poor at the time of their employment, a mine closure could render them into a status called ‘transitional poverty’. This study also highlights that mineworkers who are skilled for mining operations only do not overcome the status of ‘transitional poverty’ and hence enter a phase called ‘chronic poverty’. This stage constitutes their inability to negotiate livelihood strategies and livelihood outcomes that could sustain a household. Thus humanitarian assistance would be needed from outside sources. Planning for unexpected mine closures should also be on the agenda of the mining industry due to the extreme consequences such an event holds for the mining community experiencing the event. In the case under investigation, the unexpected mine closures occurred in the Grootvlei mine in Springs and the Orkney mine owned by the Aurora Empowerment Systems Ltd. at the time of this study. These closures left the surrounding communities in need of food, shelter and clean water. The inhabitants gradually lost their livelihood assets. A contingency planning model is proposed at the end of this study to address the short-term and long-term consequences of an unexpected mine closure. / M Development and Management, North-West University, Potchefstroom Campus, 2014
83

Understanding the Problems in Volume Production and their Connections to Management of New Product Introduction Projects : A Case Study of the Project Management Factors and the Appurtenant Production Effects from Ramp-Up of New Product in Production for Contract Electronics Manufacturing

Frost, Niclas January 2016 (has links)
The ongoing globalization of companies has resulted in a highly competitive business climate where companies have to be cost-effective but still flexible with fast response to customer feedback and present in the international scene. In order to meet the fast paced technological development from the competition and changing demand of the customers, companies focus on creating new products and reducing their time-to-market with an early product launch to gain profits from increased market shares. However, in order to maintain profitability of the new product, it becomes even more important for the company to quickly deploy a full-scale production of the product, also known as the production ramp-up phase. Despite being known as a major cost driver in new product development projects, production ramp-up is a research area which have yet received sparse attention compared to research on product launch and time-to-market in new product development projects. However, with shorter product life-cycles and higher market competition it has resulted in a need to shorten the length of a new product’s ramp-up time without making any trade-off to the cost-effectiveness of the ramp-up project and the end product’s final quality. The study identifies the common problems in volume production of a contract electronics manufacturer and their sources of disturbances from the new product introduction process. It also identifies the factors influencing the new product introduction process at the company and how these factors are connected different sources of disturbances. To identify these findings, a single case study was designed and performed at Orbit One AB, a contract electronics manufacturer with a low-volume production of products. The data collection course was executed in an iterative manner over a period of four months through interviews, observation and internal documentation and was backed up and analyzed with a literature study. The data collection through interviews was carried out in two separate rounds, where the first round of interviews was focused on identifying the common problems in volume production and the second round was focused on the factors influencing the output from the new product introduction process. The discoveries from the interviews were analyzed together with the other sources of collected data to reach a conclusive analysis. The results of the study showed that the most common problems in volume production of the company could be traced to six different sources of disturbances: Product, Production System, Design-Production Interface, Quality, Resource Management, and Personnel. The most common problems could also be summarized as: Problems with manufacturability of product; High variation of process performance, Poor correctness of information, Quality issues with products, and High workload on resources. The factors identified in the findings of the study shows that there are multiple and connected factors which affects the final output of the new product introduction process which corroborates with earlier studies and research in the area of production ramp-up. The study did identify two factors which has not been identified by other ramp-up studies, these were: Lack of organizational project culture and customer flexibility.
84

Mine closure : a contingency plan to mitigate socio-economic disasters / Maria Elizabeth Ackermann

Ackermann, Maria Elizabeth January 2013 (has links)
The history of the mining industry indicates a lack of understanding among the decision-makers of the impact the closure of mines has on the industry and the associated effects on the society and surrounding environment. The policies of the mining industry do make provision for a planned mine closure, but not for an unexpected closure. This detrimental aspect of closures in the mining industry is highlighted in the present study. The present study investigates how mineworkers’ dependency on their employment at a mine affects their ability to sustain their livelihoods. Vulnerable livelihoods leave the community at a greater risk to be affected by a disaster, than the livelihoods of a community that is resilient and has sustainable resources. Even though mineworkers are not considered as poor at the time of their employment, a mine closure could render them into a status called ‘transitional poverty’. This study also highlights that mineworkers who are skilled for mining operations only do not overcome the status of ‘transitional poverty’ and hence enter a phase called ‘chronic poverty’. This stage constitutes their inability to negotiate livelihood strategies and livelihood outcomes that could sustain a household. Thus humanitarian assistance would be needed from outside sources. Planning for unexpected mine closures should also be on the agenda of the mining industry due to the extreme consequences such an event holds for the mining community experiencing the event. In the case under investigation, the unexpected mine closures occurred in the Grootvlei mine in Springs and the Orkney mine owned by the Aurora Empowerment Systems Ltd. at the time of this study. These closures left the surrounding communities in need of food, shelter and clean water. The inhabitants gradually lost their livelihood assets. A contingency planning model is proposed at the end of this study to address the short-term and long-term consequences of an unexpected mine closure. / M Development and Management, North-West University, Potchefstroom Campus, 2014
85

Production ramp-down strategy : Optimisation of production ramp-down at Scania Engine Assembly

Otteblad, Gustav, Svensson, Jakob January 2022 (has links)
In the light of the increasing demands and competition in the automotive industry to rapidly introduce new products to the market, management of production ramp-ups and production ramp-downs has become a new decisive competitive factor. For this reason, a well-designed strategy has become essential to succeed. For Scania Engine Assembly, this novel challenge is underway in the form of a ramp-down of the old assembly line (DL) and simultaneous ramp-up of the new assembly line (DW). This is to deliver the new and more sustainable engine platform Super. DL consists of a basic assembly and a final assembly (TMS-line), where the latter was the focus of this thesis project. Since the transition is already put in motion, there is an urgent need for the establishment of a production ramp-down strategy stretching until the complete transition. Therefore, this project was initiated to develop an optimal strategy of the production ramp-down with regard to interconnected projects and functions, as well as to the factors of economics, efficiency, ergonomics, and quality. The project also aimed to establish an ideal project progression regarding the management and implementation of the strategy. Considering that the TMS-line involves 59 workstations, more than 200 personnel daily, 10 engine types with unique variants, different technical systems, and must align with multiple operational functions, a comprehensive and considered strategy was essential. An additional objective was to reduce the gap in research between production ramp-up and production ramp-down. Although, the interest of production ramp-up has increased considerably in the last two decades, that of production ramp-down still remains widely neglected, despite their similar importance. Hence, the project aimed not only to contribute to Scania, but also to contribute with empirical data to future research in production ramp-down. Altogether, the reduction in the research gap can contribute to more sustainable production systems. To achieve the project objective and aims, a substantial literature review was conducted and a wide array of scientific methods were used. The literature review established a basis for the project, and brought theories from multiple languages and standpoints together to culminate in a comprehensive understanding of production ramp-down. The scientific methods were used to gather empirical data and to design the strategy. In addition, relevant expertise was incorporated throughout the project by a continuous cooperation with Scania employees of different roles and specialisations. The project also followed Scania’s change process to facilitate the realisation of the strategy. In total, three distinctive strategy concepts were generated and evaluated, called Alpha, Beta, and Gamma. Then, after a systematic evaluation process, a combination of Alpha and Gamma was designed in detail to form the final strategy. The strategy can be described as a stepwise capacity reduction. The first step is the planning and preparation for the necessary competence shift, organisational changes, and technical solutions. In the second step, a new takt and work standard corresponding to 50% capacity is implemented. Also, a decision regarding the final production years is made to either offshore production, change layout, or continue without change. The third step involves major structural changes in the form of a new organisational structure and the implementation of a technical solution for a permanent 50% capacity reduction. Similarly, in the fourth step, the technical solution is adjusted and a new work standard is implemented to correspond to a 33% capacity need. The fifth step regards the phase-out of the TMS-line, which completes the transition between DL and DW. Finally, the sixth step includes the revitalisation of the freed-up operational area and recycling of production equipment and materials. Altogether, the strategy ensures an optimal production ramp-down of the TMS-line with regard to interconnected projects, functions, and factors. To ensure the success of the strategy, recommendations in management and implementation of the strategy were established based on research and empirical findings. The result is an optimal strategy that fulfils the objective and aims, and contributes with new empirical findings and recommendations for future research in production ramp-down and connected research fields. / Med bakgrunden av det ökande kraven och konkurrensen i fordonsindustrin att snabbt introducera nya produkter till marknaden, har ledning av produktionsupprampningar och produktionsnedrampningar blivit en ny avgörande konkurrensfaktor. För att lyckas med denna ledning krävs en välutvecklad strategi. För Scania motormontering pågår denna nya utmaning i formen av en nedrampning av den gamla monteringslinan (DL) och samtida upprampning av den nya monteringslinan (DW). Detta genomförs för att leverera den nya och mer hållbara motorplattformen Super. DL består av en grundmontering och en slutmontering (TMS-line), där den sistnämnda utgör fokus i detta examensarbete. Eftersom övergången redan är i gång finns det ett brådskande behov för utformningen av en produktionsnedrampningsstrategi som sträcker sig fram till den fullständiga övergången. Därför initierades detta projekt för att utveckla en optimal strategi för produktionsnedrampningen med hänsyn till sammankopplade projekt och funktioner, likväl till ekonomi, effektivitet, ergonomi och kvalitet. Projektet ämnade även till att utforma en idealisk projektprogression gällande styrning och implementering av strategin. Då TMS-line involverar 59 arbetsstationer, över 200 operatörer dagligen, 10 motortyper med unika varianter, olika tekniska system, och måste anpassas till flera operationella funktioner, krävdes en heltäckande och genomtänkt strategi. Ett ytterligare mål var att minska forskningsgapet mellan produktionsupprampning och produktionsnedrampning. Även om intresset för produktionsupprampning har ökat avsevärt de senaste två decennierna, frånses produktionsnedrampning fortfarande trots deras liknande betydelse. Därför ämnade projektet inte bara till att bidra till Scania, men också till att bidra med empirisk data till framtida forskning inom produktionsnedrampning. Sammantaget kan minskningen av forskningsgapet bidra till mer hållbara produktionssystem. För att uppnå projektets syfte och mål utfördes en omfattande litteraturstudie och olika vetenskapliga metoder användes. Litteraturstudien upprättade en grund för projektet, och sammanförde teorier från flera språk och perspektiv för att ge en heltäckande förståelse av produktionsnedrampning. De vetenskapliga metoderna användes till att samla empirisk data och designa strategin. Dessutom integrerades relevant expertis genom hela projektet genom ett kontinuerligt samarbete med anställda på Scania med olika roller och specialiseringar. Projektet följde även Scanias förändringsprocess för att underlätta implementeringen av strategin.  Totalt skapades och utvärderades tre distinkta strategikoncept: Alfa, Beta, och Gamma. Efter en systematisk utvärderingsprocess designades en kombination av Alfa och Gamma i detalj till att utforma den slutliga strategin. Strategin kan beskrivas som en stegvis kapacitetsreducering. Det första steget utgör planeringen och förberedelsen gällande kompetensskifte, organisatoriska förändringar, och tekniska lösningar. I det andra steget implementeras en ny takt och arbetsstandard motsvarande 50 % kapacitet. Dessutom görs ett beslut gällande de sista produktionsåren att antingen flytta produktion utomlands, ändra layout, eller fortsätta utan förändring. Det tredje steget involverar stora strukturella förändringar i formen av en ny organisatorisk struktur och implementeringen av en teknisk lösning för en permanent kapacitetreducering på 50 %. I det fjärde steget justeras den tekniska lösningen och en ny arbetsstandard implementeras motsvarande ett kapacitetsbehov på 33 %. Det femte steget berör utfasningen av TMS-line vilket slutför övergången mellan DL och DW. Slutligen inkluderar det sjätte steget vitaliseringen av den frigjorda operationella ytan och återvinningen av produktionsutrustning och material. Sammantaget säkerställer strategin en optimal produktionsnedrampning av TMS-line med hänsyn till sammankopplade projekt, funktioner och faktorer. För att säkerställa strategins framgång upprättades rekommendationer i styrning och implementering baserat på forskning och empiriska fynd. Resultatet är en optimal strategi som uppfyller syfte och mål, samt bidrar med nya empiriska fynd och rekommendationer till framtida forskning i produktionsnedrampning och relaterade forskningsfält.
86

Triggningskriterier i triggningsmodul för trådlösa dataloggern DL141E / Triggering Criteria in Trigger Module for Wireless Data Logger DL141E

Jovanovic, Aleksandar, Vu, Cong January 2018 (has links)
Dataloggern DL141E möjliggör kontinuerlig loggnig av mätdata från sensorer på upp till 30k sampel/s, som vidare kan överföras till mobiltelefoner via trådlös kommunikation. Detta är dock för stora datamängder per tidsenhet för mobiltelefoner som är tekniskt begränsade. Därför önskas bara relevant mätdata för att reducerar denna onödiga datamängd. I denna studie föreslås ett tillvägagångssätt där enspecifik mindre samling av diskreta försampel loggas i tur och ordning. Varje samling signalbehandlas genom att ställas mot fördefinierade triggningskriterier för att trigga loggning av en stor uppsättning av sampel på bara intressanta signalavvikelser. Dessa triggningskriterier är en särskild nivåöverskridning och signalriktning i kombination med ett antal sampel i följd. Studien förser en granskning av hur signalberäkningsmetoden ”Lebesgue sampling” kan tillämpas med kriterierna för god träffsäkerhet och en skälig beräkningstid i mobiltelefoner. Detta beaktas med dataloggerns vanligaste signaltyper puls och ramp i en miljö där småbrus och transienter förekommer. Träffsäkerheten och beräkningsbördan beaktasför att bedöma Lebesgue metodens effektivitet och antal nödvändiga försampel per uppsättning. Implementeringen görs i Java Android plattform och integreras därefter i en digital triggningsmodul med Graphical User Interface (GUI). / With the data logger DL141E it’s possible to continuously log measurement data from sensors up to 30k samples per second, and then transferring them to a mobile phone with Bluetooth technology. But this is by far too much sample data in a small time for a mobile phone with technical limitations to receive. That’s why only relevant measurement data should be mass logged to reduce the unnecessary data amount. Int his study a new approach is proposed where a specific and smaller amount of discrete pre-samples are logged in sequence. Every set of pre-samples is processed by comparing them to the user pre-defined trigger criterias. Met criterias will trigger logging of a massive set of samples on basis of only interesting signal deviations. The following trigger criterias are used: a specific signal level to cross, a specific signal direction, and both of these in combination with an amount of consecutive samples. The study provides an examination on how the signal processing method ”Lebesgue sampling” can be applied with the above criterias to achieve a god accuracy with reasonable processing time on mobile phones. This is observed using sensors with the most common signal types ramp and pulse in an environment where small noises and transients occur. The accuracy and the processing load are taken into account when estimating the efficiency of Lebesgue method and when estimating how many pre-samples per set might be sufficient. The implementation is written in Java Android platform and then integrated into a digital triggering module with Graphical User Interface (GUI).
87

TILLGÄNGLIGHET I KULTURHISTORISKA BYGGNADER : En fallstudie om Hospitalsgatan, Långgatan och Kyrkogatan med fokus på kulturvärdet, säkerhetsrisker och tekniska åtgärder för ramp, hiss och dörr i Strängnäs kommun

Al-Dabbagh, Lara, Noel, Miriam, Matti, Fadi January 2023 (has links)
Purpose: This study aims to assess the three cultural historical buildings located in the municipality of Strängnäs, that doesn’t meet the accessibility requirements currently.  Therefore, the aim is to suggest solutions for each three buildings that could be useful to different authorities in the future. The focus is on wheelchair users using the buildings with the help of technical installations such as ramp, elevators, and accessible doors. The study will be based on the social-, historical-, and aesthetic aspect as well as the safety risk. Method: The method for this study is based on a literature study, and a case study, alongside with reference objects which will be the inspiration for our results. The literature study is based on fact-gathering from books and the internet which provides the study with information on cultural historical buildings, laws and regulations concerning the private buildings, cultural values, and with various safety risks. While the reference objects inspired our proposals for the measures, the case study was used to gather information in form of an interview, site visits, and communal document analysis. Results: The result of thisstudy provides measures for each of the three studied objects. Changes made to the first building, Hospitalsgatan 15, focuses on the side entrance with a ground slope pointing down towards it. Thereby the following indoor changes presents threshold ramp, and a stairlift. For the secondary building, Långgatan 9 E-F, there was suggestions made such as using an outer ramp with an idle plan. There should also be an indoor loose ramp, and a stairlift. The third building, Kyrkogatan 13, had suggestions by installing an outdoor platform lift with an adjusted idle plan in front of the outer stairs and threshold ramp. In comparison to the first mentioned building, the focus for the last two buildings were on the main entrance. All these measures were considered to reach an accessibility in cultural historical building while also keeping in mind the cultural value of the building and its safety risks. Conclusions: The study concludes that the social-, historical-, and aesthetic aspect as well as the safety risk works a crucial role in shaping the proposed solutions for the three buildings and contributes to the accessibility improvements. By adopting appropriate technical installations and considering the cultural significance of these structures, accessibility in cultural historical buildings can be achieved effectively.
88

Using UX design principles for comprehensive data visualisation / Tillämpning av UX designprinciper för omfattande datavisualisering

Ali, Umar, Sulaiman, Rabi January 2023 (has links)
Workplace safety, particularly in manual handling tasks, is a critical concern that hasbeen increasingly addressed using advanced risk assessment tools. However, pre-senting the complex results of these assessments in an easily digestible format re-mains a challenge. This thesis focused on designing and developing a user-friendlyweb application to visualise risk assessment data effectively. Grounded in a robusttheoretical framework that combines user experience principles, and data visualisa-tion techniques. The study employed an iterative, user-centric design process to de-velop the web application. Multiple visualisation methods, such as pie charts for vis-ualising risk distribution, bar chart, and line chart for time-based analysis, were eval-uated for their effectiveness through usability testing. The application's primary con-tribution lies in its efficient data visualisation techniques, aimed at simplifying com-plex datasets into actionable insights. This work lays the groundwork enabling futuredevelopment by pinpointing areas for improvement like enhanced interactivity andaccessibility. / Belastningsergonomiska risker i arbetsmiljön, särskilt i uppgifter som involverarmanuell hantering, är en kritisk fråga som alltmer har adresserats med hjälp av avan-cerade riskhanteringsverktyg. Men att presentera de komplexa resultaten av dessabedömningar i ett lättillgängligt format kvarstår som en utmaning. Denna avhand-ling fokuserade på att designa och utveckla en användarvänlig webbapplikation föratt effektivt visualisera riskbedömningsdata. Studien bygger på en robust teoretiskram och kombinerar principer för användarupplevelse med datavisualiseringstekni-ker. Webbapplikationen har utvecklats med hjälp av en iterativ och användarcentre-rad designprocess. Flera visualiseringsmetoder, såsom cirkeldiagram för att visuali-sera riskfördelning, stapeldiagram och linjediagram för tidsbaserad analys, utvärde-rades för deras effektivitet genom användningstester och utvärderingsformulär. Ap-plikationens primära bidrag ligger i dess effektiva datavisualiseringstekniker, somsyftar till att förenkla komplex information till handlingsbara insikter. Detta arbetelägger grunden och möjliggör framtida utveckling genom att peka ut områden förförbättring, som förbättrad interaktivitet och tillgänglighet.
89

Zuflussregulierung als Konzept eines selbstorganisierten Störfallmanagements zur Vermeidung von Gridlocks

Lötzsch, Florian 25 September 2015 (has links) (PDF)
Traffic jams are the cause of approximately 25 billion euro of annual expenses of the state of Germany [14, 26]. In addition to these monetary damages they also have a negative effect on the quality of life for man and nature. They are, for example, the source of a non-negligible part of the 2.4 billion traffic accidents with damage of property or persons registered annually [13]. Circa 14 % of crashes result from previous mishaps [8, 26]. Almost all of them cause further jam formation and therefore a vicious circle which is in danger of closing around. Especially jams being created from spontaneous, non-periodic incidents involve a high risk of ending in a gridlock and thereby disrupt a whole traffic system. Because these disturbances are unpredictable and unpreventable, their duration and impact can merely be reduced by an effective incident management through the systematic, planned and coordinated use of institutional, technical and natural resources. The self-healing-network-strategy by Lämmer [19] and Rausch [27] is one example of such a countermeasure against jam formation in urban road networks. It prevents gridlocks at intersections by means of traffic lights and the combination of two effective mechanisms. Extended off-times prevent the inflow into oversaturated sections and so the expansion of tailbacks onto upstream intersections. Extended green periods of alternative directions of travel motivate drivers to avoid disturbed sectors and thus additionally allow a better exploitation of available free capacities. The development and successful establishment of this method could make the use of ramp metering in urban networks - which is regulating the inflow of oversaturated areas by reducing or skipping green times as well - invalid. To answer this question the presented master’s thesis aims at comparing both inflow-regulating control concepts. However, it is not the ambition to proof that one method is worse than the other, but to contribute to an ideal combination of both instead - with the intention to eliminate deficits on either side. Therefore both concepts will be reviewed in a first step and subsequently the contribution of additional effects against gridlock creation through the symbiosis of the two traffic light controls is analysed. Furthermore, several suggestions for the development of an efficient ramp metering logic are introduced to configure this combination to be more beneficial. / Verkehrsstaus verursachen dem deutschen Staat jährlich rund 25 Milliarden Euro Unkosten [14, 26]. Neben diesen monetären Schäden wirken sie sich jedoch auch negativ auf die Lebensqualität von Mensch und Umwelt aus. Sie sind beispielsweise die Ursache für einen nicht unerheblichen Anteil der circa 2,4 Milliarden jährlich registrierten Unfälle mit Sach- oder Personenschaden [13]. Rund 14 % der Unglücksfälle gehen dabei als Folgeerscheinung eines vorherigen Unfalls hervor [8, 26]. Nahezu alle führen eine weitere Staubildung herbei und somit einen Teufelskreis, der sich zu schließen droht. Besonders aus spontanen, nicht wiederkehrenden Störfällen entstandene Staubildung birgt eine hohes Risiko, in einem Gridlock zu enden und damit ein gesamtes innerstädtisches Verkehrssystem zum Erliegen zu bringen. Da diese Störfälle unvorhersehbar und unvermeidbar sind, kann ihrer Dauer und ihrem Einfluss lediglich ein effizientes Störfallmanagement durch systematischen, gezielten und koordinierten Gebrauch institutioneller, technischer und natürlicher Ressourcen entgegenwirken. Beispiel für eine solche Gegenmaßnahme zur Staubildung in urbanen Netzen ist das selbstorganisierte Störfallmanagement nach Lämmer [19] und Rausch [27]. Mithilfe von LSA und der Kombination zweier effektiver Wirkungsmechanismen werden Gridlocks an Knotenpunkten unterbunden. Verlängerte Sperrzeiten verhindern den Zufluss in übersättigte Streckenabschnitte und damit die Ausbreitung von Rückstaus auf vorgelagerte Kreuzungen. Erweiterte Freigabezeiten der alternativen Fahrtrichtungen regen wiederum eine Umgehung des gestörten Abschnitts an und ermöglichen somit zusätzlich die bessere Ausschöpfung vorhandener freier Kapazitäten. Durch die Entwicklung und den erfolgreichen Einsatz der genannten Maßnahme könnte der Gebrauch von Pförtnerampeln (PA), welche den Zufluss in übersättigte Bereiche ebenfalls regulieren, indem sie Grünzeiten verkürzen oder aussetzen, hinfällig werden. Um diese Frage zu klären, widmet sich die vorliegende Masterarbeit dem Vergleich der beiden zuflussregulierenden Steuerungskonzepte. Ziel ist jedoch nicht, zu beweisen, dass eine Maßnahme schlechter ist als die andere, sondern vielmehr einen Beitrag zu einer optimalen Kombination der Vorzüge beider Herangehensweisen zu leisten und somit die auf beiden Seiten vorhandenen Defizite zu beseitigen. Dafür werden zunächst beide Konzepte auf ihre Effizienz hin überprüft und im Anschluss analysiert, inwiefern die Symbiose beider LSA-Steuerungen in einem Netzwerk zusätzliche Effekte gegen die Gridlockentstehung bewirkt. Außerdem werden verschiedene Vorschläge zur Entwicklung einer effizienteren Steuerlogik für Pförtneranlagen eingebracht, um diese Kombination noch vorteilhafter zu gestalten.
90

Critical Factors for Production Ramp-up in High Technology Companies : A case study at an aerospace company

Svensson, Philip, Blom, Johannes January 2019 (has links)
Purpose - A research gap was identified in relation to the production related factors during ramp-up. Therefore, the purpose of the study was to “simplify production ramp-up by defining how measures could be prioritised in high technology company.” Method – The study used a single-case study method with a qualitative and explorative approach. This method was used to gain in-depth knowledge of the case. The study was conducted at Saab, a high technology company within the aerospace industry. Findings – The findings included a list of critical factors for ramp-up control and two additional critical factors that are relevant to high technology companies, along with five additional measures. From the case the main critical factors were related to personnel, education and experience. Implications – The study has contributed with a simplified ramp-up control method with implications for high technology industries. The new method will contribute to a more effective time to volume phase relevant for both practitioners and researchers. Limitations - As the study uses a new ramp-up control method it has only been applied to one case. The complete data from the case cannot be showcased due to secrecy.

Page generated in 0.0743 seconds