• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 67
  • 15
  • 4
  • 4
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 143
  • 143
  • 39
  • 18
  • 17
  • 15
  • 15
  • 13
  • 12
  • 12
  • 12
  • 12
  • 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.
101

Hyra eller köpa rörläggarutrustning? / Renting or buying pipelaying - equipment?

Forsgårdh, Felix, Dahlin, Karl January 2019 (has links)
This report will try to give clarity in when and if it is most advantageous for a specific pipelaying entrepreneur to invest in buying pipelaying-equipment or renting it to their pipelaying-projects. The purpose of the report is also to give the reader a good perception of both alternatives as it could be a useful tool in future procurements. The information and prices that is used for the calculations in this report are gathered through the entrepreneur’s calculation-section, interviews with field-experts, rental companies, books and publications and internet. The report is limited to equipment that pipelayers normally are in need of in projects and the specific usage percentage is not used in the calculations. The result in this report shows what equipment is needed in a typical pipelaying-project and when it is best economically for a company to buy or rent their equipment both as individual articles and as a complete set. The result also shows that the hourly rate of buying the equipment is far less than the rate of renting it. It also brings up critical factors for investment-calculating regarding pipelaying-equipment. / Denna rapport ska skapa en ökad kunskap om och i sådana fall när det för ett specifikt företag inom mark- och anläggningsbranschen i Stockholmsområdet är fördelaktigt att själva investera eller hyra sin rörläggarutrustning i interna VA- projekt. Syftet med arbetet är även att kunna ge en god uppfattning av bägge kostnadsalternativen då det kan vara till nytta att använda sig av i framtida upphandlingar. Den information och de priser som legat till grund för beräkningarna i rapporten är inhämtade genom företagets ekonomiavdelning, intervjuer med sakkunnig personal, mailkontakt med hyresföretag samt informationssökning i litteratur, publikationsdatabaser samt internetsidor. Arbetet avgränsas till utrustning som rörläggare är i behov av för att klara av sitt dagliga arbete samt att den exakta nyttjandegraden av utrustningen inte vägs in i beräkningarna som återfinns i arbetet. Resultatet i den här rapporten visar vad som bör ingå i en typisk utrustning som en rörläggare behöver för att kunna utföra sitt arbete och när man tjänar på att hyra alternativt köpa sin rörläggarutrustning både som separata artiklar och som en komplett rörläggarcontainer. Arbetet visar också att själva timpriset för att köpa utrustningen är avsevärt lägre än timpriset för att hyra utrustningen. Slutligen tar rapporten upp avgörande faktorer för investeringskalkylering av rörläggarutrustning.
102

Operator and Machine Models for Dynamic Simulation of Construction Machinery

Filla, Reno January 2005 (has links)
VIRTUAL PROTOTYPING has been generally adopted in product development in order to minimise the traditional reliance on testing of physical prototypes. It thus constitutes a major step towards solving the conflict of actual increasing development cost and time due to increasing customer demands on one side, and the need to decrease development cost and time due to increasing competition on the other. Particularly challenging for the off-road equipment industry is that its products, working machines, are complex in architecture. Tightly coupled, non-linear sub-systems of different technical domains make prediction and optimisation of the complete system’s dynamic behaviour difficult. Furthermore, in working machines the human operator is essential for the performance of the total system. Properties such as productivity, fuel efficiency, and operability are all not only dependent on inherent machine properties and working place conditions, but also on how the operator uses the machine. This is an aspect that is traditionally neglected in dynamic simulations, because the modelling needs to be extended beyond the technical system. The research presented in this thesis focuses on wheel loaders, which are representative for working machines. The technical system and the influence of the human operator is analysed, and so-called short loading cycles are described in depth. Two approaches to rule-based simulation models of a wheel loader operator are presented and used in simulations. Both operator models control the machine model by means of engine throttle, lift and tilt lever, steering wheel, and brake only – just as a human operator does. Also, only signals that a human operator can sense are used in the models. It is demonstrated that both operator models are able to adapt to basic variations in workplace setup and machine capability. Thus, a “human element” can be introduced into dynamic simulation of working machines, giving more relevant answers with respect to operator-influenced complete-machine properties such as productivity, fuel efficiency, and operability already in the concept phase of the product development process. / <p>ISRN/Report code: LiU-Tek-Lic 2005:44</p>
103

Design of a Swappable Battery Pack

Blom, Carl, Sjögren, Elias January 2024 (has links)
The electric vehicle market has rapidly expanded due to technological advancements for the last decade and a key enabler is the development of high-performance batteries with greater energy density, faster charging, and longer lifespan. The construction equipment sector faces unique challenges in electrification, including high power demands, extended operating hours, and the need for minimal downtime. To address these challenges Volvo Construction Equipment is investigating a battery swap system solution that allows for quick battery swaps, reducing downtime and a decoupled lifetime from the machines. The aim for this study is to design a battery pack used for the battery swap system while answering the following research questions: RQ1: What configuration of battery modules, rack and auxiliary systems achieve the highest energy density when designing a battery pack for construction equipment? RQ2: What factors should be considered when designing the battery modules, rack, and auxiliary systems to achieve the highest energy density of a battery pack for construction equipment? This project followed a limited version of Ulrich et al.'s (2019) product development process, focusing on concept development and system-level design for a battery swapping system. An inductive research approach was taken, gathering qualitative and quantitative data from interviews, literature, documents, and meetings to create a holistic understanding of the project challenges. A structured literature review was conducted using relevant keywords across multiple databases, employing techniques like forward and backward snowballing. Data analysis methods, including conversation analysis, were employed to structure and analyze collected data, ensuring validity and reliability through triangulation, and cross-referencing with experts at Volvo. Empirical studies were conducted through benchmarking and a case study, providing quantitative data on specifications and qualitative insights from internal documentation and communication with product developers. The findings formed an iterative concept generation process, emphasizing the importance of exploring diverse possibilities in the early stages. The design process involved evaluating previous battery pack solutions, working within predefined constraints like using a specific shell, internally developed battery modules, auxiliary components while satisfying a set of stakeholder needs. Some auxiliary components and a rack that supports the battery modules were also developed as there is a new internal layout of the battery pack. This resulted in a conceptual battery pack that theoretically have a 30% higher energy density than the previous battery pack solutions. The proposed solution enables Volvo Construction Equipment to offer machines with longer runtimes and increased productivity by maximizing the energy storage capacity within the given constraints.
104

A study investigating the factors that causes delays in construction equipment projects in UX/HMI area / En studie som undersöker de faktorer som orsakar förseningar i byggutrustningsprojekt i UX/HMI-området

Shivalika, Shivalika January 2023 (has links)
This research study investigates the factors contributing to delays in construction equipment projects, specifically in the User Experience (UX) and Human-Machine Interface (HMI) area, with a particular focus on projects conducted at the company Volvo Construction Equipment. The study incorporates a literature review, a mixed-methods approach combining qualitative and quantitative analysis, and in-depth discussions. Through the analysis of existing literature, the study identifies various factors associated with delays in construction equipment projects, including unclear project requirements, challenges in integrating systems and technologies, communication and collaboration issues, inadequate project management practices, and external influences. Building upon this foundation, qualitative interviews and quantitative surveys were conducted to gather insights from project managers, engineers, and other stakeholders at Volvo Construction Equipment. The findings from the data analysis highlight the frequency and average duration of delays in the UX/HMI area of construction equipment projects. Key contributing factors include communication issues, changes in project requirements or scope, insufficient resources or manpower, delays in component/material delivery, and lack of coordination among teams. These factors significantly impact project performance. Participants in the study reported employing various strategies to mitigate these delays, such as improving communication channels, enhancing cross-functional collaboration, investing in training and skill development, and closely monitoring project requirements. The research outcomes provide valuable insights into the relationships between identified factors and project delays in the UX/HMI area at Volvo Construction Equipment. The results emphasize the importance of addressing these factors through improved planning, effective communication, collaboration, and resource management to enhance project efficiency. Furthermore, the study contributes to the field of UX/HMI in construction equipment projects by shedding light on the specific challenges faced by the company and providing recommendations to improve project management practices and minimize delays. Recommendations to future research directions include longitudinal studies to assess the long-term impact of implemented strategies, exploration of emerging technologies in the UX/HMI domain, and evaluation of different project management methodologies for their effectiveness in addressing delays. By addressing these research gaps, further advancements can be made to optimize the UX/HMI area of construction equipment projects, ensuring successful project outcomes. / Denna forskningsstudie undersöker faktorer som bidrar till förseningar i produktutvecklingsprojekt av arbetsmaskiner, specifikt inom användarupplevelse (UX) och människa-maskin-gränssnitt (HMI), med särskilt fokus på projekt som genomförs vid företaget Volvo Construction Equipment. Studien innefattar en litteraturöversikt, en blandad metodansats som kombinerar kvalitativ och kvantitativ analys samt fördjupade diskussioner. I analysen av befintlig litteratur identifieras olika faktorer som är förknippade med förseningar i denna typ av projekt, inklusive oklara projektkrav, utmaningar att integrera system och teknik, kommunikations- och samarbetsproblem, otillräckliga projektledningsmetoder och externa påverkningar. Med denna grund genomfördes kvalitativa intervjuer och kvantitativa enkäter för att samla insikter från projektledare, ingenjörer och andra intressenter vid Volvo Construction Equipment. Resultaten från dataanalysen belyser frekvensen och genomsnittlig varaktighet av förseningar inom UX/HMI-området för denna typ av projekt. Nyckelfaktorer inkluderar kommunikations-problem, ändringar i projektkrav eller omfattning, otillräckliga resurser eller arbetskraft, förseningar i leverans av komponenter/material och brist på samordning mellan team. Dessa faktorer påverkar projektets prestanda avsevärt. Deltagarna i studien rapporterade att de använder olika strategier för att mildra dessa förseningar, såsom att förbättra kommunikations-kanaler, förbättra tvärfunktionellt samarbete, investera i utbildning och kompetensutveckling samt noggrant övervaka projektkrav. Resultaten ger värdefulla insikter i sambanden mellan identifierade faktorer och projekt-förseningar inom UX/HMI-området på Volvo Construction Equipment. Vikten av att hantera dessa faktorer genom förbättrad planering, effektiv kommunikation, samarbete och resurshantering för att förbättra projekteffektiviteten betonas särskilt. Vidare bidrar studien till fältet UX/HMI inom denna typ av projekt genom att belysa de specifika utmaningar som Volvo Construction Equipment står inför och ge rekommendationer för att förbättra projektlednings-metoder och minimera förseningar. Framtida forskningsriktningar som rekommenderas inkluderar longitudinella studier för att bedöma den långsiktiga effekten av implementerade strategier, utforskning av framväxande teknik inom UX/HMI-domänen och utvärdering av olika projektledningsmetodiker gällande deras effektivitet i att hantera förseningar. Genom att ta itu med detta kan ytterligare framsteg göras för att optimera UX/HMI-området för produktutvecklingsprojekt av arbetsmaskiner och säkerställa framgångsrika projektresultat.
105

Low Loss Articulated Hauler Axle : A Conceptual Study / Lågförlustaxel till ramstyrd dumper : En konceptstudie

Andersson, Patrik, Wallin, Morgan January 2017 (has links)
Volvo Construction Equipment is highly regarded for robust products, but with an increasing competition in their market, development of the product portfolio is more important than ever. One step being carried out is to reduce losses in powertrains and increase the fuel efficiency for solutions such as articulated haulers and wheel loaders. This would eventually lower the fuel costs and emissions for the end customer. With this development, Volvo CE could strengthen their position in the market while also contributing to reducing the construction industry's environmental impact. By investigating the front bogie axle of the recently introduced hauler, Volvo A60H, important information about possible reductions and the distribution of the current losses were found. The investigation focused on a front bogie axle, but some of the results are applicable for other applications such as wheel loaders as well, since a lot of the technology in the axles are similar. A conceptual study was performed where completely new ideas were generated, such as implementing a dry sump system in the axle, as well as ideas for improving the subcomponents currently found in the axle. Two cases were presented for the evaluation of concepts, one with a fully loaded dump body and low speeds, and one with an unloaded dump body and a wider speed interval. The concepts were later evaluated using calculation tools such as MATLAB and a Simulink-model was created for the losses in the axle. When combining concepts that reduces load dependent losses, a potential reduction of 64% of the axle's total losses was achieved for the case with a full dump body. The largest improvement found for the load independent losses was 8% with an unloaded hauler and the highest speed investigated, 50 km/h. A dry sump system improves the axle's efficiency with 45% in optimal working conditions, but was found to lower the efficiency at other conditions. Room for improvement of axle losses currently exists both for load dependent and load independent losses. The evaluation performed pointed towards the load dependent losses being the largest influence on the total losses, even with an unloaded dump body and high speeds. This is an interesting observation since a lot of work at Volvo CE has revolved around reducing the load independent losses since these are easier to affect with different lubrication levels and rotational speeds. A test methodology for load dependent losses should be implemented in order to validate the results of this thesis work, and also to aid further development at Volvo CE.
106

Investigation of rotational velocity sensors

Törnquist, Martin January 2008 (has links)
<p><p>To improve the speed measurement of construction equipment, different sensor technologies have been investigated. Many of these sensor technologies are very interesting but to keep the extent of the thesis only two was chosen for testing, magnetic absolute angle sensors using Hall and GMR technology, to investigate if those are a valid replacement for the current measurement system that is using a passive sensor. Tests show that these sensors are capable of speed measurement, but because of noisy angle estimates they need filtering for good speed computation. This filtering introduces a large time delay that is of significance for the quality of the estimate. A Kalman filter has been implemented in an attempt to lower the time delays but since only a very simple model has been used it does not give any improvements over ordinary low pass filtering. For these sensors the mounting tolerance is of great interest. For best performance the offset between the sensor and magnet centres need to be kept small for both sensors. This is due to a non-linearity effect this causes. The distance between the sensors and the magnet is not critical for linearity issues, but only for the quality of the signal, where it might drop out when the distance is too large. This is where the sensor using GMR technology stands out. Compared to the Hall technology sensor, the GMR sensor can handle distances that are more than 10 times larger. The conclusion is that these sensors can be a valid replacement of the current measurement system. They will introduce more functionality with the capability of detecting rotational direction and zero velocity. In an application with more than one sensor they can also be used for more purposes, like detecting slip in clutches etc. Depending on the application, the time delays may not be critical, else more work need to be done to improve the estimate, e.g. with a more advanced model for the Kalman filter.</p></p><p> </p>
107

Forecasting Management

Jessen, Andreas, Kellner, Carina January 2009 (has links)
<p>In a world that is moving faster and faster, a company’s ability to align to market changes is becoming a major competitive factor. Forecasting enables companies to predict what lies ahead, e.g. trend shifts or market turns, and makes it possible to plan for it. But looking into the future is never an easy task.</p><p>“Prediction is very difficult, especially if it’s about the future.” (Niels Bohr, 1885-1962)</p><p>However, progress in the field of forecasting has shown that it is possible for companies to improve on forecasting practices. This master thesis looks at the sales forecasting practices in MNCs primarily operating in emerging and developing countries. We examine the whole process of sales forecasting, also known as forecasting management, in order to develop a comprehensive model for forecasting in this type of companies. The research is based on a single case study, which is then later generalized into broader conclusions.</p><p>The conclusion of this master thesis is that forecasting is a four-step exercise. The four stages we have identified are: Knowledge creation, knowledge transformation, knowledge use and feedback. In the course of these four stages a company’s sales forecast is developed, changed and used. By understanding how each stage works and what to focus on, companies will be able to improve their forecasting practices.</p>
108

Investigation of rotational velocity sensors

Törnquist, Martin January 2008 (has links)
To improve the speed measurement of construction equipment, different sensor technologies have been investigated. Many of these sensor technologies are very interesting but to keep the extent of the thesis only two was chosen for testing, magnetic absolute angle sensors using Hall and GMR technology, to investigate if those are a valid replacement for the current measurement system that is using a passive sensor. Tests show that these sensors are capable of speed measurement, but because of noisy angle estimates they need filtering for good speed computation. This filtering introduces a large time delay that is of significance for the quality of the estimate. A Kalman filter has been implemented in an attempt to lower the time delays but since only a very simple model has been used it does not give any improvements over ordinary low pass filtering. For these sensors the mounting tolerance is of great interest. For best performance the offset between the sensor and magnet centres need to be kept small for both sensors. This is due to a non-linearity effect this causes. The distance between the sensors and the magnet is not critical for linearity issues, but only for the quality of the signal, where it might drop out when the distance is too large. This is where the sensor using GMR technology stands out. Compared to the Hall technology sensor, the GMR sensor can handle distances that are more than 10 times larger. The conclusion is that these sensors can be a valid replacement of the current measurement system. They will introduce more functionality with the capability of detecting rotational direction and zero velocity. In an application with more than one sensor they can also be used for more purposes, like detecting slip in clutches etc. Depending on the application, the time delays may not be critical, else more work need to be done to improve the estimate, e.g. with a more advanced model for the Kalman filter.
109

Forecasting Management

Jessen, Andreas, Kellner, Carina January 2009 (has links)
In a world that is moving faster and faster, a company’s ability to align to market changes is becoming a major competitive factor. Forecasting enables companies to predict what lies ahead, e.g. trend shifts or market turns, and makes it possible to plan for it. But looking into the future is never an easy task. “Prediction is very difficult, especially if it’s about the future.” (Niels Bohr, 1885-1962) However, progress in the field of forecasting has shown that it is possible for companies to improve on forecasting practices. This master thesis looks at the sales forecasting practices in MNCs primarily operating in emerging and developing countries. We examine the whole process of sales forecasting, also known as forecasting management, in order to develop a comprehensive model for forecasting in this type of companies. The research is based on a single case study, which is then later generalized into broader conclusions. The conclusion of this master thesis is that forecasting is a four-step exercise. The four stages we have identified are: Knowledge creation, knowledge transformation, knowledge use and feedback. In the course of these four stages a company’s sales forecast is developed, changed and used. By understanding how each stage works and what to focus on, companies will be able to improve their forecasting practices.
110

Effects Of Separate And Intergrinding On Some Properties Of Portland Composite Cements

Soyluoglu, Serdar 01 January 2010 (has links) (PDF)
In the production of cement, to increase the cement/clinker ratio and decrease CO2 emission, the most important alternative is to produce mineral admixture incorporated cements (CEM II-III-IV-V) instead of portland cement (CEM I). These cements are usually produced by intergrinding the portland cement clinker and the mineral admixtures. However, the difference between grindabilities of the different components of such cements may cause significant effects on the particle size distribution and many other properties. For this reason, separate grinding of additives and clinker may be thought as an alternative. In this study, the effects of intergrinding and separate grinding on the particle size distribution and consequently on the strength of portland composite cements which contained natural pozzolan (trass), granulated blast furnace slag (GBFS) and limestone besides portland cement clinker were studied.

Page generated in 0.1615 seconds