The automotive industry is in constant development and in recent years the environmental legislations have been getting tougher. The need for lighter and stronger materials has increased according to these changes and composite materials such as carbon fibre reinforced polymers is showing potential of being a solution due to their high specific properties. This thesis is an investigation and design proposal for one way of making a carbon fibre bus body wall structure by the use of pultruded beam elements and a certain number of standardised node elements. This is done to increase the possibility of mass production and possibly lower the manufacturing cost for a carbon fibre structure. The methodology is based on a product development process where a market research as well as a literary study was conducted initially to see what work had been done in the area. Needs were investigated and formulated to a product specification from which concepts was generated using brainstorming methods as well as discussions with bus design engineers at Scania. A number of materials and manufacturing methods was analysed for the node elements and after comparing and scoring different concepts, a carbon fibre node element was chosen. Dimensioning calculations were made based on standardised tests which simulates different driving scenarios. The concept was then designed in 3D-cad and the final weight of the concept was measured to 194 kg. A comparison of the concept with a steel bus was made by the use of the life cycle analysis tool in CES Edupack 2017 which resulted in a difference of 47 tonnes carbon dioxide released for a diesel driven light goods vehicle during the first six years of the lifetime. The overall results show that a carbon fibre bus body might be economically beneficial during the entire lifetime of a bus even though the purchase price is higher.

In this dissertation, energy efficient hydraulic systems are studied. The research focuses on solutions for linear actuators in mobile applications, with emphasis on construction machines. Alongside the aspect of energy efficiency, the thesis deals with competing aspects in hydraulic system design found in the development of construction machines. Simulation models and controls for different concepts are developed, taking the whole machine into account. In line with this work, several proof of concept demonstrators are developed. First, pump controlled systems are studied and a novel concept based on an open-circuit pump configuration is conceived. Special consideration is paid to multi-mode capabilities that allow for a broadened operating range and potential downsizing of components. Simulation models and controls are developed and the system is experimentally validated in a wheel loader application. Second, the possibility for energy recuperation in valve controlled systems is investigated. In such solutions, a hydraulic motor, added to the meter-out port, is used for energy recovery during load lowering and in multi-function operation. Recuperated energy is either be used momentarily or is stored in a hydraulic accumulator. The proposed solution means an incremental improvement to conventional systems, which is sometimes attractive to machine manufacturers due to fewer uncertainties in reliability, safety and development cost. The energy recovery system is studied on a conceptual level where several alternative systems are proposed and a concept based on a two-machine hydraulic pressure transformer is selected for a deeper control study followed by experimental validation. Third, so-called `common pressure rail' systems are suggested. This technique is well established for rotary drives, at least for the industrial sector. However, in applying this technique to mobile hydraulics, feasible solutions for linear actuators are needed. In this dissertation, two approaches to this problem are presented. The first one is the hydraulic pressure transformer, studied in simulation as the key-component of a `series hybrid' topology for wheel loaders. In the second approach variable displacement linear actuators (VDLA) based on a 4-chamber cylinder and multi-mode control is applied. In a theoretical study a model predictive control approach is suggested and new insights to the trade-off between controllability and energy efficiency of a multi-chamber cylinder are presented. Finally, a fullscale hydraulic hybrid system based on secondary controlled hydraulic motors and VDLAs is designed and experimentally validated on a large excavator.

D.Phil.

No description available.

The purpose of this thesis is to analyze the maturity and the performance of the currently available roaming solutions that provide interoperability and roaming services to Electrical Vehicle Charging Networks. At least three different entities are involved in an Electrical Vehicle (EV) charging roaming scenario, namely the EV, the home charging network and the visited charging network. All of these entities have to interface and interact with each other on the physical and the communication protocols level. The Open Clearing House Protocol (OCHP) roaming protocol is implemented and its performance is evaluated against the e-Clearing.net test platform. The protocol functionality for billing and its suitability for different scenarios is also evaluated. Furthermore, an extension to the protocol is proposed to support prepaid subscription, and its performance is also estimated. The findings of this study have verified the performance and the maturity of the OCHP protocol, and strongly recommends the implementation of roaming protocols and clearing houses. The estimated performance of the proposed extension confirmed that both prepaid and postpaid billing can be realized using the tested roaming protocol and clearing house implementations.

The pantograph-catenary system is used in railways to transfer electric power from infrastructure to trainset. As the pantograph slides against the catenary, the contact between the two surfaces is not stable due to stiffness variation, propagating wave and other environmental perturbation, especially at high speeds or in multi-pantograph operation. Heavy oscillation can result in poor power-transmission quality, electromagnetic interference, severe wear or even structural damage. So the pantograph-catenary dynamics has become one of the key issues which limits the operational speed and determines the maintenance cost. There are many types of catenary systems in Sweden, which are relatively soft and sensitive compared with the systems in other countries. They work well at low operational speed and have strict limitations to multi-pantograph operation. It is possible to achieve an operational speed of 350 km/h on newly-built high-speed lines, but there is still a large demand for higher operational speed and more capacity on the existing lines.     Many researchers and engineers have made progress to improve its dynamic performance. From the research aspect, many numerical models have been built up to demonstrate the dynamics of the pantograph-catenary system and to unveil the key influencing factors. There have been many applications developed in recent years. Regarding the catenary, high-tensile loads on the catenary and low-stiffness-variation designs are widely used to improve the dynamic performance. Regarding the pantograph, aerodynamic-friendly designs and active-control technique contribute to the development of high-speed pantograph. But all these methods need not only large investment but long out-of-service. Considering the large scale and heavy service duty of the existing lines, it becomes almost impossible to completely upgrade the existing pantograph-catenary systems. So it is necessary to find practical and efficient methods to exploit the potentials of the existing systems to enhance their dynamic performances.     This thesis investigates the dynamic behaviour of the Swedish pantograph-catenary systems and proposes methods for better usage. A numerical study on multi-pantograph operation is performed and the relationships between dynamic performance and some key parameters is established. By studying the multi-pantograph operation at short spacing distance, a method to use the leading pantograph as auxiliary pantograph is proposed to increase the operational speed on the soft catenary system. To ensure operational safety in abnormal conditions, numerical studies on pantograph raising/lowering processes and in catenary overlap sections are performed. By studying the influence of the lumped-mass on the dynamic performance, it shows that it is even possible to implement some artificial tuned-masses on the catenary for dynamic optimization. / <p>QC 20170915</p>

Studien fokuserar på tillverkningen av Volvo v90. Mer specifikt monteringen av en expander runt tanklocket. Monteringen sker på rear quarter panel stationen och det finns ett kvalitetsproblem där. Den manuella monteringen görs inte rätt varje gång och detta leder till problem framöver i produktionen. Studiens syfte är att ta fram fler förslag till motåtgärder och förbättringar. Med hjälp av ett uppbyggt teoretiskt ramverk i form av andra vetenskapliga artiklar har ett flertal förslag tagits fram. Tre nya tekniker, några ändringar med Lean som riktlinjer och ett förslag till designändring beskrivs vidare i texten. Vidare ges även förslag på hur Volvo Cars kan arbeta vidare med förbättringsförslagen i framtiden för att upprätthålla hög kvalité. De metoder som används för att ta fram förslagen till motåtgärder är DMAIC, intervju, observation och en litteraturstudie. En analys genomförs för att utvärdera huruvida förslagen är försvarbara eller inte. Inget om själva implementeringen i verkligheten kommer att finnas med i rapporten / The present study analyzes the quality issues occurring during the assembly of the expander around the fuel cap while manufacturing Volvo v90. The assembling process is done manually at the rear quarter panel station. The main objective of the current investigation was to analyze the problems that Volvo Cars AB is facing currently and suggest quality improvement tools and techniques.  To define, measure and analyze the above-mentioned problem, the DMAIC method has been used. Interviews, observations, and a thorough literature study has been conducted and potential improvement proposals are suggested.  As a result of the current study, three new techniques for detecting quality problems early in the production process, several improvement suggestions with Lean as guideline and a suggestion for design change is proposed. Furthermore, suggestions are also given on how Volvo Cars can continue to work with improvements in the future to maintain a high quality throughout.

No description available.

Centrifugal compressors are mechanical devices that move and compress gas and are used in a wide range of applications. To get as much efficiency out of the compressors as possible, high demandsare put on having good compressor models. One method of compressor modeling is the curve fitting method, where empirical and mathematical models are used to parameterize relationships between different compressor characteristics. The models come in a vast variety of formats, complexity and difficulty of applying them. With the variety of compressors and models to select from, it is important to select an appropriate model. A tool for automatic parameterization, evaluation and selection of compressor model would be very useful. A model library is proposed in the thesis that utilizes the Total Least Squares method for parameterizing and evaluating the models. By initializing the model library with measurement data, called a compressor map, the compressor is broken down into smaller components in a hierarchy, based on physical expressions and characteristics. The individual compressor models are defined and parameterized on top of the base model, overriding and replacing the base model feature. Total Least Squares offers a countermeasure to avoid large model prediction errors associated with the nonlinear behavior of the compressor. To utilize the model library further, a simulation interface is proposed, so the selected compressor model can easily be applied in an engine and vehicle simulation environment. The model library is evaluated using three different compressor maps and shows promising results, where the TLS method seem to better capture bad visual curve-fitted models, compared to other simpler methods. Parameterization of the models are done automatically without any manual user input needed. The simulation interface is tested by replacing the compressor block of an engine simulation model, where the results show that the model component hierarchy can be integrated in a simulation environment.

abstract: The California Department of Transportation (Caltrans) is required to comply with the National Pollution Discharge Elimination (NPDES) permit, which includes the infiltration of stormwater runoff from highways and implementing soil based best managements practices (BMPs). Stormwater BMPs are in place to prevent pollution in stormwater runoff as well as to facilitate the stormwater discharge from the road. Per this new permit, Caltrans is to install soil based BMPs that can absorb the 85th percentile of a 24-hour stormwater event. In order to absorb the stormwater runoff, the area used is the Clear Recovery Zone (CRZ), which are the road embankments/slopes located adjacent to the roadside. The CRZ must be traversable and recoverable in order to meet roadside traffic safety standards. A major concern for Caltrans is the uncertainty on how these BMPs will affect the safety of a vehicle, if a vehicle were to interact with the soft soils. In order to provide an insight on the effects of the BMPs, the modeling and simulation of vehicle dynamics under certain interactions between the roadside, soil, and vehicle was completed. The research used computer simulations to quantify the probability of rollover accidents under several different vehicle, driving and ground conditions. The vehicles traversing typical archetype roadsides on soft soil are simulated using MsMac3D software. It was important to model the properties of the vehicle, roadside, mechanical and hydraulic properties of soils realistically in order to obtain an accurate representation of a real-world vehicle and soil interaction. The outcome was a library of simulations that provided quantifiable data on the effect that soft soils have on the safety and rollover potential of a vehicle traversing the CRZ. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019