Abstract
A questionnaire survey has been conducted in Belgium, Denmark, Germany, Poland, Spain and Sweden in 2016-2017. Once every third month through one year respondents have received a link to an online questionnaire which asked them about information on any traffic accidents they might have experienced in the period. Different procedures for gaining respondents were used in each country, resulting in relatively small and skewed sample sizes from Germany, Poland and Spain, causing data analysis based on these numbers to be highly unreliable. Thus results are based on data from Belgium, Denmark and Sweden."br/""br/"The study aims at providing an input to Task 5.3 on socio-economic costs within the InDeV project. Thus the questionnaire contains questions on various aspects related to the accidents that might contribute with costs as well as basic accident information such as means of transport and time of the accident."br/""br/"A special focus in the survey is on pedestrian single accidents, which are not normally considered traffic accidents. The survey finds that more than 80% of the pedestrian accidents that have been self-reported are in fact single accidents, which illustrates the need for further investigation of the pedestrian single accidents as the number of these might be quite high. The study also provides knowledge of basic consequences of the pedestrian falls, for instance 16% result in medical treatment, 14% in one or more days of absence from work and 37% in property damage."br/""br/"The self-reported traffic accidents have proved difficult to compare with official accident statistics, both due to different national guidelines on what constitutes a reportable accident and to the legal limitations on personal information which may be asked in the questionnaire; this eliminates the possibility of combining information with official accident records. However, based on the self-reports it can be concluded that in 8% of the accidents the respondent have been in contact with the police. Document type: BookAbstract
A questionnaire survey has been conducted in Belgium, Denmark, Germany, Poland, Spain and Sweden in 2016-2017. Once every third month through one year respondents have received a link to an online questionnaire which asked them about information on any traffic accidents they might [...]Abstract
Two smartphone applications were developed with the aim of harvesting insights of vulnerable road user accidents. The apps require a backend database with software tools for generating and managing questionnaires, etc. Such a system was developed using a MySQL database where a user-friendly platform has been developed in CakePHP. The backend system has been successfully developed and been used to handle more than 11,000 participants. The original idea was to monitor VRU via apps to detect when they may have been involved in an accident as pedestrian or cyclist based on the motion patterns from the smartphone's motion sensors (accelerometer, gyroscope) and collect as much information as possible regarding the accident automatically (e.g. time and location of the accident). If an accident was detected, the road user should receive a questionnaire to provide detailed information of the accident (e.g. road surface conditions, lighting conditions, other road users involved). This app was used by more than 400 participants resulting in a large amount of data. Document type: Report
Abstract
Two smartphone applications were developed with the aim of harvesting insights of vulnerable road user accidents. The apps require a backend database with software tools for generating and managing questionnaires, etc. Such a system was developed using a MySQL database where a [...]
Abstract
With the aim of assessing the extent and nature of naturalistic studies involving vulnerable road users, a systematic literature review was carried out. The purpose of this review was to identify studies based on naturalistic data from VRUs (pedestrians, cyclists, moped riders and motorcyclists) to provide an overview of how data was collected and how data has been used. In the literature review, special attention is given to the use of naturalistic studies as a tool for road safety evaluations to gain knowledge on methodological issues for the design of a naturalistic study involving VRUs within the InDeV project. The review covered the following types of studies: Â Studies collecting naturalistic data from vulnerable road users (pedestrians, cyclists, moped riders, motorcyclists). Â Studies collecting accidents or safety-critical situations via smartphones from vulnerable road users and motorized vehicles. Â Studies collecting falls that have not occurred on roads via smartphones. Four databases were used in the search for publications: ScienceDirect, Transport Research International Documentation (TRID), IEEE Xplore and PubMed. In addition to these four databases, six databases were screened to check if they contained references to publications not already included in the review. These databases were: Web of Science, Scopus, Google Scholar, Springerlink, Taylor & Francis and Engineering Village. The findings revealed that naturalistic studies of vulnerable road users have mainly been carried out by collecting data from cyclists and pedestrians and to a smaller degree of motorcyclists. To collect data, most studies used the built-in sensors of smartphones, although equipped bicycles or motorcycles were used in some studies. Other types of portable equipment was used to a lesser degree, particularly for cycling studies. The naturalistic studies were carried out with various purposes: mode classification, travel surveys, measuring the distance and number of trips travelled and conducting traffic counts. Naturalistic data was also used for assessment of the safety based on accidents, safety-critical events or other safety-related aspect such as speed behaviour, head turning and obstacle detection. Only few studies detect incidents automatically based on indicators collected via special equipment such as accelerometers, gyroscopes, GPS receivers, switches, etc. for assessing the safety by identifying accidents or safety-critical events. Instead, they rely on self-reporting or manual review of video footage. Despite this, the review indicates that there is a large potential of detecting accidents from naturalistic data. A large number of studies focused on the detection of falls among elderly people. Using smartphone sensors, the movements of the participants were monitored continuously. Most studies used acceleration as indicator of falls. In some cases, the acceleration was supplemented by rotation measurements to indicate that a fall had occurred. Most studies of using kinematic triggers for detection of falls, accidents and safety-critical events were primarily used for demonstration of prototypes of detection algorithms. Few studies have been tested on real accidents or falls. Instead, simulated falls were used both in studies of vulnerable road users and for studies of falls among elderly people. Document type: Report
Abstract
With the aim of assessing the extent and nature of naturalistic studies involving vulnerable road users, a systematic literature review was carried out. The purpose of this review was to identify studies based on naturalistic data from VRUs (pedestrians, cyclists, moped riders [...]
Abstract
Two smartphone applications were developed with the aim of harvesting insights of vulnerable road user accidents. The apps require a backend database with software tools for generating and managing questionnaires, etc. Such a system was developed using a MySQL database where a user-friendly platform has been developed in CakePHP. The backend system has been successfully developed and been used to handle more than 11,000 participants. The original idea was to monitor VRU via apps to detect when they may have been involved in an accident as pedestrian or cyclist based on the motion patterns from the smartphoneâs motion sensors (accelerometer, gyroscope) and collect as much information as possible regarding the accident automatically (e.g. time and location of the accident). If an accident was detected, the road user should receive a questionnaire to provide detailed information of the accident (e.g. road surface conditions, lighting conditions, other road users involved). This app was used by more than 400 participants resulting in a large amount of data.Abstract
Two smartphone applications were developed with the aim of harvesting insights of vulnerable road user accidents. The apps require a backend database with software tools for generating and managing questionnaires, etc. Such a system was developed using a MySQL database where a user-friendly [...]Abstract
Purpose – The purpose of this research is to investigate how manufacturing organisations can decrease their environmental impact in the supply chain. To meet the purpose, two research questions were formulated: 1. How can a manufacturing organisation reduce its environmental impact caused by transportation? 2. How can a manufacturing organisation reduce its environmental impact caused by production? Method – To provide the opportunity to reach a conclusion and to create a basic understanding of the research area, a literature review was conducted, which formed the basis of the theoretical framework. Through a case study at a manufacturing organisation, interviews and document analyses were used as sources for empirical data. In order to develop solutions and recommendations, collected data and theoretical framework were analysed and discussed. Findings – The research findings indicate that there are several possible measures to implement to reduce an organisation's environmental impact in the supply chain. A decisive factor is creating a holistic and fundamental understanding of sustainability and enabling everyone involved to work according a common view and in the same direction. In addition, a requirement to pursue the same goal is that all stakeholders are involved where a prerequisite is a well-functioning internal communication. Implications – The research did not contribute to any new theories, but through the research analysis, statements and theories from previous research were strengthened. The research suggests actions that can be used for organisations to reduce their environmental impact, but also to increase the understanding of why actions should be implemented. Society has an important responsibility for motivating and provide conditions for manufacturing organisations to reduce their footprint. This research is considered to lead to an improved environment in the form of lower emission levels where both organisations and the entire community take responsibility for the planet. Limitations – The case study is designed as a single-case study which, from a validity perspective, is not considered as advantageous as a multiple case study because the results are difficult to generalize. In order to strengthen the study's reliability, several functional units and / or organisations could have been included in the study.Abstract
Purpose – The purpose of this research is to investigate how manufacturing organisations can decrease their environmental impact in the supply chain. To meet the purpose, two research questions were formulated: 1. How can a manufacturing organisation reduce its environmental impact [...]Abstract
To reduce the emissions from the transport sector, the electric vehicle (EV) is a promising alternative to the internal combustion engine vehicle (ICEV). An important aspect of implementing new transport systems in terms of EVs is the charging strategy, as many energy sources with different limitations can be utilized. Although various studies have investigated charging strategies for electric cars, there is a lack of optimized charging strategies for electric boats with specific considerations for these cases. In Colombia, the river transport sector plays an important role in areas with lack of access to other transport alternatives. This study presents an optimization of the charging strategy for an electric boat that is planned to traffic the Magdalena River in the region of Magangué, Colombia. The objective of the optimization model is to minimize the electricity bill while maintaining a desired transport service. The study considers solar photovoltaics (PV), the electric grid and battery storage for charging, and compares different battery sizes in a scenario analysis. Furthermore, the impact of the instability of the grid is included in terms of a sensitivity analysis of grid blackouts, together with varying battery investment costs. The results show that PV is a recommended investment as it lowers the charging cost and gives positive results in terms of economic feasibility. To further increase the economic feasibility, lower the charging costs and improve the reliability of the system, it is suggested to invest in energy storage. The techno-economic feasibility of storage is heavily affected by battery investment costs and number of grid blackouts affecting the boat charging. If the investment cost is low and the number of blackouts is high, a large storage is a suggested solution. För att minska utsläppen från transportsektorn är elfordon (EV) ett lovande alternativ till förbränningsmotorfordon (ICEV). En viktig aspekt vid implementering av nya transportsystem för EV:s är val av laddningsstrategi, eftersom många energikällor med olika begränsningar kan användas. Även om flertalet studier har undersökt laddningsstrategier för elbilar, saknas optimerade laddningsstrategier för elbåtar och som beaktar de specifika förhållandena för dessa fall. I Colombia spelar flodtransportsektorn en viktig roll i områden med brist på tillgång till andra transportalternativ. Denna studie presenterar en optimering av laddningsstrategin för en elbåt som är planerad att trafikera floden Magdalena i regionen Magangué, Colombia. Syftet med optimeringsmodellen är att minimera elräkningen samtidigt som en önskad transporttjänst bibehålls. Studien omfattar solceller (PV), elnätet och batterilagring för laddning, och jämför olika batteristorlekar i en scenarioanalys. Vidare inkluderas effekterna av elnätets instabilitet genom en känslighetsanalys av strömavbrott, tillsammans med varierande kostnader för batteriinvesteringar. Resultaten visar att PV är en rekommenderad investering eftersom den sänker laddningskostnaden och ger positiva resultat när det gäller ekonomisk lönsamhet. För att ytterligare öka den ekonomiska lönsamheten, sänka laddningskostnaderna och förbättra systemets tillförlitlighet föreslås det att investera i energilagring. Den teknisk-ekonomiska genomförbarheten för lagring påverkas starkt av kostnader för batteriinvesteringar och antalet strömavbrott som påverkar båtladdningen. Om investeringskostnaden är låg och antalet strömavbrott är högt är energilagring med stor kapacitet en föreslagen lösning.Abstract
To reduce the emissions from the transport sector, the electric vehicle (EV) is a promising alternative to the internal combustion engine vehicle (ICEV). An important aspect of implementing new transport systems in terms of EVs is the charging strategy, as many energy sources with [...]Abstract
Due to increasing penetration of decentralized variable renewable energy generators and the increasing demand of electrical power due to the electrification of the heat and transport sectors, low voltage grids are facing critical problems. Deviation of the permitted voltage range and local overloads of the grid equipment, are the two main issues that are compromising a smooth distribution grid operation. An intelligent integration of distributed generators, heat-pumps and electric vehicles into a Smart Grid, allows the flexibility that they intrinsically provide, to be used by distribution system operators to avoid critical grid conditions. Smart grid suppliers currently available on the market, have been categorized into Local, Decentralized and Centralized Smart Grid Concepts. Their main difference is represented by the level of control, communication and coordination that they make use of. The aim of the thesis was to evaluate the effectiveness of solution of the Smart Grid Concepts implementation in specific low voltage grids, especially in term of voltages and loadings mitigation capabilities, to be used as a decision making tool for future smart grid implementations. A control architecture that emulates the way the analyzed Smart Grid Concepts operate, has been implemented in Python and tested on three different low voltage distribution networks in DigSILENT PowerFactory. The control architecture is an algorithm that communicates to DigSILENT PowerFactory how the Smart Grid needs to operate in response to detected critical grid conditions. The flexibility that the Smart Grid Concepts make use of, are battery storage, active power curtailment and reactive power compensation from photovoltaic inverters and demand side management by means of electric vehicles and heat pumps. In particular, in order to make most use of the available flexibility, an intelligent electric vehicles charging strategy has been implemented as well as an intelligent heat pump operation. Both static worst-case simulations and time-dependent simulations, over a winter and a summer day, for different penetration scenarios, have been carried out. The summary of the simulation results showed that while the Decentralized Smart Grid Concept, if the flexibility is available, is always able to keep voltages and loadings between their critical values, the Local Smart Grid Concept is not able to do the same for the loadings. På grund av ökad penetration av decentraliserade variabla förnybara energikällor och den ökande efterfrågan på elkraft på grund av elektrifiering av värme- och transportsektorn, står lågspänningsnätet inför kritiska problem. Avvikelse av det tillåtna spänningsområdet och lokala överbelastningar av nätutrustningen är de två huvudproblemen som äventyrar en smidig nätdrift. En intelligent integration av distribuerade generatorer, värmepumpar och elektriska fordon i ett smart nät, tillåter flexibiliteten som de egentligen tillhandahåller, för att undvika kritiska rutnätförhållanden. Smartnätleverantörer som för närvarande är tillgängliga på marknaden har system som kategoriserats som lokalt, decentraliserat och centralt Smart Grid Concepts. Deras huvudsakliga skillnad representeras av den nivå av kontroll, kommunikation och samordning som de utnyttjar. Syftet med avhandlingen var att utvärdera effektiviteten av lösningen av implementeringen av Smart Grid Concepts i specifika lågspänningsnät, särskilt när det gäller spänningar och belastningsreducerande förmågor, som ska användas som beslutsverktyg för framtida smarta nätverksimplementeringar. En reglerarkitektur som emulerar hur ett analyserat Smart Grid Concepts fungerar, har implementerats i Python och testats på tre olika lågspänningsdistributionsnä i DigSILENT PowerFactory. Kontrollarkitekturen är en algoritm som kommunicerar med DigSILENT PowerFactory hur Smart Grid bör fungera som svar på detekterade kritiska gridförhållanden. Den flexibilitet som Smart Grid Concepts använder sig av är batterilagring, aktiv strömavbrott och reaktiv effektkompensation från fotovoltaiska omvandlare och efterfrågesidan hantering med elbilar och värmepumpar. I synnerhet för att på bästa sätt utnyttja den tillgängliga flexibiliteten har en intelligent laddningsstrategi för elfordon implementerats liksom en intelligent värmepumpsoperation. Både statiska wärsta fall simuleringar och tidsberoende simuleringar, över en vinter och en sommardag, för olika penetrationsscenarier har utförts. Sammanfattningen av simuleringsresultaten visade att medan det decentraliserade Smart Grid Conceptet, om flexibiliteten är tillgänglig, alltid kan hålla spänningar och belastningar mellan sina kritiska värden, kan det lokala Smart Grid Concepts inte göra samma för belastningarna.Abstract
Due to increasing penetration of decentralized variable renewable energy generators and the increasing demand of electrical power due to the electrification of the heat and transport sectors, low voltage grids are facing critical problems. Deviation of the permitted voltage range [...]Abstract
over the world, raising concerns about energy conservation and the environmental impacts of greenhouse gas emissions has promoted the development of a sustainable mobility transition. Successful electric vehicle (EV) deployment plays a vital role in this manner but is still facing obstacles, where public charging infrastructure is one of them. Additionally, digitization is transforming and introducing new industries worldwide, contributing with new constructs to be used in the evolving transition. Simultaneously, technology is surpassing the competition, and is one of the most potent transformational force affecting customer relations in the energy sector, leading to customers anticipating more from the power utility companies. To attain a long-termsustainable competitive advantage, firms have to retain, sustain, and nurture their customer base. To do so, corporations have comprehended the value of embracing customer-centric incentives, enabling them to capture more indirect business values. Furthermore, this thesis was done in collaboration with a power utility company, referred to as ‘Org X’ or ‘the CPO’. Influenced by the reasoning above, it investigated the opportunity to create indirect business values through a demand-driven roll-out of the national charging infrastructure with the use of crowdfunding. This was achieved by adopting an exploratory methodology approach, where a mixed inductive-deductive design was used. A multi-method qualitative data collection was made; consisting mainly of semi-structured-, and unstructured interviews with experts in the field. Thus, a profound perspective of the EV-charging market landscape was attained, which enabled adequate reasoning when proposing a strategy approach for the cause. Additionally, quantitative secondary data was used to develop a tool for an initial location evaluation, that is part of the recommended approach. This tool was also used to enhance the understanding of the national EV-charging market landscape, the customer segments, as well the potential market for a co-creating platform. The findings suggest that the perceived readiness level of crowdfunding charging infrastructure varies depending on what aspect that is being accommodated. A platform that connects stakeholders is encouraged by actors in the field, but crowdfunding through solely end-users is questioned as close proximity to the end-user’s location is a key-factor regarding motivation to fund a charging point. A ‘Tier based framework’, that facilitates this transition was therefore developed and evaluated. Additionally, the framework was considered in the market analysis case study, which further included a recommended implementation and communication approach. If used accordingly, this framework could bring both indirect- and direct business values to the power utility company in question, as well as the involved stakeholders. Oro över energieffektiviseringar och miljökonsekvenser från utsläpp av växthusgaser världen över har främjat utvecklingen av ett hållbart energisystem. En framgångsrik marknadspenetration av elbilar (EVs) har en viktig roll i denna aspekt, men står fortfarande inför hinder där publik laddningsinfrastruktur är en del av problemet. Digitaliseringen leder till transformation och nya industrier vilket bidrar med ytterligare konstruktioner som används i övergången till ett mer hållbart samhälle. Samtidigt driver teknikutvecklingen till ökad konkurrens och har en kraftfull påverkan på vad kunderna förväntar sig från företagen. För att uppnå mer långsiktigt hållbara konkurrensfördelar måste företag sträva efter att behålla, upprätthålla och ta hand sin kundbas. Företag börjar förstå det ökade värde som finns i att utöva mer kundcentrerade incitament och strategier, vilket potentiellt bidrar till mer indirekta affärsvärden. Denna uppsats är i samarbete med ett Svenskt energiföretag, följaktligen refererat till som 'Org X' eller 'CPO'. Baserat på resonemanget ovan, har möjligheten att skapa indirekta affärsvärden genom verkställandet av en mer efterfrågedriven utveckling av den nationella elbilsladdning infrastruktur med hjälp av crowdfunding undersökts. Detta uppnåddes genom att använda ett utforskat tillvägagångssätt, där en blandad induktiv-deduktiv design användes. En kvalitativ datainsamling gjordes på flera sätt; huvudsakligen bestående av semistrukturerade och ostrukturerade intervjuer med experter inom området. Således uppnåddes ett djupgående perspektiv på av elbilsladdning marknaden vilket möjliggjorde sakliga resonemang kring den presenterade och rekommenderade strategin. Ytterligare användes kvantitativ sekundärdata för att utveckla ett verktyg för en initial plats bedömning, vilket är en del av den rekommenderade strategin. Detta verktyg användes dessutom för att öka förståelsen för den nationella elbilsladdning marknaden, kundsegmenten, liksom den potentiella marknaden för en samskapande plattform. Resultaten tyder på att den upplevda beredskapsnivån att crowdfunda laddningsinfrastruktur varierar beroende på plats och kundgrupp. En plattform som ansluter intressenter uppmuntras av aktörer på marknaden, men crowdfunding genom enbart slutanvändare ifrågasätts då närhet till slutanvändarens läge är en nyckelfaktor när det gäller motivationen att medverka i finansieringen. Därav har ett tier based framework utvecklats och presenterats, som bör underlätta transformationen mot en mer kunddriven affärsmöjlighet. Dessutom beaktades ramverket i fallstudien för marknadsanalysen, som ytterligare inkluderade en rekommenderad strategi för implementering och kommunikation. Om den används i enlighet bör ramverket ge både indirekta och direkta affärsvärden till det aktuella energi företaget, liksom till berörda intressenter.Abstract
over the world, raising concerns about energy conservation and the environmental impacts of greenhouse gas emissions has promoted the development of a sustainable mobility transition. Successful electric vehicle (EV) deployment plays a vital role in this manner but is still facing [...]Abstract
With the rise of smart manufacturing technologies and a shift towards a new industrial revolution, brings forth many new challenges, one of which is how to adapt and integrate these technologies into existing assembly lines. Scania CV AB has joined this race and, with the help of smart manufacturing solutions, works on increasing efficiency amongst its assembly lines. This thesis is aimed at creating concept designs using different smart manufacturing technologies in the assembly line of a pedal car, to evaluate and adapt the concept suited for a real assembly line. The thesis starts with studying the different smart manufacturing technologies to better understand them and the scientific methods used. This follows up with the methodology where several scientific methods such as morphological matrix and weight based decision making matrix are used to generate and evaluate different concept designs. This is followed by a qualitative analysis that helps in selecting the concept design that best suits the needs of the assembly line under consideration. The different concepts are visualized and the evaluation based on different parameters are discussed. This thesis lays a foundation to realize that an aggregate of an optimized process plan, a continuous improvement strategy and the right use of smart manufacturing technologies contributes to the productivity of the assembly line in the long run. Med en ökning av smarta tillverkningsteknologier och ett skift mot en ny industriell revolution, kommer nya utmaningar. Av dessa utmaningar ifrågasätts hur man anpassar och kombinerar dessa olika teknologier gentemot existerande monteringslinjer. Scania CV AB har tagit del i denna resa och, med hjälp av smarta tillverkningslösningar, jobbar ständigt mot att effektivisera sina monteringslinjer. Detta examensarbete fokuserar på att använda olika och smarta tillverkningsteknologier i en monteringslina för tillverkning av en trampbil. Detta görs genom att evaluera och anpassa olika koncept som är lämpade för en verklig monteringslina. Examensarbetet börjar med en undersökning av nuläget för att få en bättre uppfattning om smarta tillverkningsteknologier samt de vetenskapliga metoder som används. Även här så undersöks referensprodukten - trampbil samt de olika programvarorna AviX, ExtendSim och LayCAD. Genom att ha satt tydliga arbetsmetoder och följt upp mot dessa så diskuterar och hänvisar nästa kapitel resultaten. Resultaten visar hur olika koncept har tagits fram samt vilka teknologier som går ihop med dessa. Fördelar, nackdelar och risker hos respektive teknologi har benämnts. Ett systematiskt arbetssätt har tagits fram mot hur man anpassar konceptet för monteringslinan av en trampbil till en verklig monteringslina, samt hur man har jobbat runt de restriktioner som uppkommit. Examensarbetet slutar med ett kapitel där slutsatserna, på en överskådlig nivå, tas fram. Hur dessa teknologier har kombinerats och evaluerats, samt att koncepterna som har tagits fram har lagt en grund för framtida projekt att följa upp emot.Abstract
With the rise of smart manufacturing technologies and a shift towards a new industrial revolution, brings forth many new challenges, one of which is how to adapt and integrate these technologies into existing assembly lines. Scania CV AB has joined this race and, with the help of [...]Abstract
In a society where environmental noise is becoming a major health and economical concern, sound emissions are an increasingly critical design factor for vehicle manufacturers. With about a quarter of the European population living close to roads with heavy traffic, traffic noise in urban landscapes has to be addressed first. The current introduction of electric vehicles on the market and the need for sound systems to alert their presence is causing a shift in mentalities requiring engineering methods that will have to treat noise management problems from a broader perspective. That in which noise emissions need not only be considered as a by-product of the design but as an integrated part of it. Developing more sustainable ground transportation will require a better understanding of the sound field emitted in various realistic operating conditions, beyond the current requirements set by the standard pass-by test, which is performed in a free-field. A key aspect to improve this understanding is the development of efficient numerical tools to predict the generation and propagation of sound from moving vehicles. In the present thesis, a methodology is proposed aimed at evaluating the pass-by sound field generated by vehicle acoustic sources in a simplified urban environment, with a focus on flow sound sources. Although it can be argued that the aerodynamic noise is still a minor component of the total emitted noise in urban driving conditions, this share will certainly increase in the near future with the introduction of quiet electric engines and more noise-efficient tyres on the market. This work presents a complete modelling of the problem from sound generation to sound propagation and pass-by analysis in three steps. Firstly, computation of the flow around the geometry of interest; secondly, extraction of the sound sources generated by the flow, and thirdly, propagation of the sound generated by the moving sources to observers including reflections and scattering by nearby surfaces. In the first step, the flow is solved using compressible detached-eddy simulations. The identification of the sound sources in the second step is performed using direct numerical beamforming with linear programming deconvolution, with the phased array pressure data being extracted from the flow simulations. The outcome of this step is a set of uncorrelated monopole sources. Step three uses this set as input to a propagation method based on a point-to-point moving source Green's function and a modified Kirchhoff integral under the Kirchhoff approximation to compute reflections on built surfaces. The methodology is demonstrated on the example of the aeroacoustic noise generated by a NACA air inlet moving in a simplified urban setting. Using this methodology gives insights on the sound generating mechanisms, on the source characteristics and on the sound field generated by the sources when moving in a simplified urban environment. I ett samhälle där buller håller på att bli ett stort hälsoproblem och en ekonomisk belastning, är ljudutsläpp en allt viktigare aspekt för fordonstillverkare. Då ungefär en fjärdedel av den europeiska befolkningen bor nära vägar med tung trafik, är åtgärder för minskat trafikbuller i stadsmiljö en hög prioritet. Introduktionen av elfordon på marknaden och behovet av ljudsystem för att varna omgivningen kräver också ett nytt synsätt och tekniska angreppssätt som behandlar bullerproblemen ur ett bredare perspektiv. Buller bör inte längre betraktas som en biprodukt av konstruktionen, utan som en integrerad del av den. Att utveckla mer hållbara marktransporter kommer att kräva en bättre förståelse av det utstrålade ljudfältet vid olika realistiska driftsförhållanden, utöver de nuvarande standardiserade kraven för förbifartstest som utförs i ett fritt fält. En viktig aspekt för att förbättra denna förståelse är utvecklingen av effektiva numeriska verktyg för att beräkna ljudalstring och ljudutbredning från fordon i rörelse. I denna avhandling föreslås en metodik som syftar till att utvärdera förbifartsljud som alstras av fordons akustiska källor i en förenklad stadsmiljö, här med fokus på strömningsgenererat ljud. Även om det aerodynamiska bullret är fortfarande en liten del av de totala bullret från vägfordon i urbana miljöer, kommer denna andel säkerligen att öka inom en snar framtid med införandet av tysta elektriska motorer och de bullerreducerande däck som introduceras på marknaden. I detta arbete presenteras en komplett modellering av problemet från ljudalstring till ljudutbredning och förbifartsanalys i tre steg. Utgångspunkten är beräkningar av strömningen kring geometrin av intresse; det andra steget är identifiering av ljudkällorna som genereras av strömningen, och det tredje steget rör ljudutbredning från rörliga källor till observatörer, inklusive effekten av reflektioner och spridning från närliggande ytor. I det första steget löses flödet genom detached-eddy simulation (DES) för kompressibel strömning. Identifiering av ljudkällor i det andra steget görs med direkt numerisk lobformning med avfaltning med hjälp av linjärprogrammering, där källdata extraheras från flödessimuleringarna. Resultatet av detta steg är en uppsättning av okorrelerade akustiska monopolkällor. Steg tre utnyttjar dessa källor som indata till en ljudutbredningsmodel baserad på beräkningar punkt-till-punkt med Greensfunktioner för rörliga källor, och med en modifierad Kirchhoff-integral under Kirchhoffapproximationen för att beräkna reflektioner mot byggda ytor. Metodiken demonstreras med exemplet med det aeroakustiska ljud som genereras av ett NACA-luftintag som rör sig i en förenklad urban miljö. Med hjälp av denna metod kan man få insikter om ljudalstringsmekanismer, om källegenskaper och om ljudfältet som genereras av källor när de rör sig i en förenklad stadsmiljö. "p"QC 20170425Abstract
In a society where environmental noise is becoming a major health and economical concern, sound emissions are an increasingly critical design factor for vehicle manufacturers. With about a quarter of the European population living close to roads with heavy traffic, traffic noise in [...]