This article explores the potential of using real-world driving patterns to derive PHEV and BEV utility factors and evaluates how different travel and recharging behaviours affect the calculation of the standard SAE J2841 utility factor. The study relies on six datasets of driving data collected monitoring 508,607 conventional fuel vehicles in six European areas and a dataset of synthetic data from 700,000 vehicles in a seventh European area. Sources representing the actual driving behaviour of PHEV together with the WLTP European utility factor are adopted as term of comparison. The results show that different datasets of driving data can yield to different estimates of the utility factor. The SAE J2841 standard method results to be representative of a large variety of behaviours of PHEVs and BEVs' drivers, characterised by a fully-charged battery at the beginning of the trip sequence, thus being representative for fuel economy and emission estimates in the early phase deployment of EVs, charged at home and overnight. However the results show that the SAE J2841 utility factor might need to be revised to account for more complex future scenarios, such as necessity-driven recharge behaviour with less than one recharge per day or a fully deployed recharge infrastructure with more than one recharge per day.

The new generation of cars are so-called Plug-in Hybrid Electric Vehicles (PHEVs) which has the grid connection capability. By the introduction of these vehicles, the grid issues will be connected to the private car transportation sector for the first time. The cars from the gird perspective can be considered as a regular load with certain power factor. The effects of this type of new load in distribution grid are studied in this thesis. By modelling the cars as regular load, the effects of the cars in three distinct areas in Stockholm are investigated. The car number in each area is estimated based on the population and commercial density of electricity consumption in the three areas. Afterward, the average electricity consumption by the cars in one day is distributed among 24 hours of the day with peak load in the studied year. This distribution is done by two regulated and unregulated methods. The regulated method is based on the desired pattern of electricity consumption of PHEVs by vehicle owners. On the other hand, the regulated pattern is designed based on encouragement of the car owners to consume electricity for charging their car batteries at low-power hours of day (usually midnight hours). The power system from high voltage lines in Sweden down to 11 kV substations in Stockholm simulated in PSS/E software has been used in this study. The automation program (written in Python) is run in order to get the output report (voltage variation and losses) of the load flow calculations for different hours of day by adding the required power for PHEVs both by regulated and unregulated patterns. The results show the possibility of introducing growing number of cars till year 2050 in each area with existing grid infrastructures. Moreover, the number of cars, yearly and daily electric consumption for PHEVs in pure electric mode are shown in this project and the effects of regulated electricity consumption are investigated. It is concluded that since the car number is estimated based on the population, the areas with higher residential characteristics are more problematic for integration of PHEVs from capacity point of view. Moreover, by regulating the charging pattern of PHEVs, the higher number of PHEVs can be integrated to the grid with the existing infrastructures. In addition, the losses have been decreased in regulated pattern in comparison with unregulated pattern with the same power consumption. The voltage in different substations is within the standard boundaries by adding 100 percent of PHEVs load for both regulated and unregulated patterns in all three areas.

The design is a modular structure, repeating itself in cities around the world. The space grid, which forms the platform for mobile housing, provides the city nomad with the ability to easily move from city to city and live with its small home anywhere.

In SKB’s Äspö Hard Rock Laboratory (HRL) a full scale test of a concrete plug,part of a sealing structure for the depository of spent nuclear fuel, has been carriedout. The aim of this thesis is to evaluate the behavior of the concrete plug and howit corresponds to assumptions made during the design. The concrete plug is domeshaped, un-reinforced and casted in situ with low-pH concrete. It will be exposed tohigh water and swelling pressures and designed for a life span of 100 years. Duringthe first years it shall also prevent water leakage from the inside of the depositiontunnel. Before the pressure is applied, the concrete plug is assumed to de-bond fromthe rock due to autogenous and cooling shrinkage. The gap between the concrete androck is then grouted during cooling and the concrete plug will hence be prestressedwhen the cooling is stopped. The concrete plug is analyzed with the measurement data from the full scale testwith comparisons to results from finite element simulations. The performed measurementsinclude form pressure, internal strain and temperature, concrete plugdisplacements in the tunnel alignment, displacements relative to the rock and ambienttemperatures. Two assumptions have been made during the evaluation; fullbond to the rock or no bond to the rock. The results are also compared to twosimilar experiment that were previously performed. The results indicate that the concrete did de-bond from the rock before grouting tosome extent. It is plausible that a selective de-bonding was obtained. Due to highwater leakage, were cables for the measurement equipment are drawn out from theconcrete plug, the concrete plug was not exposed to the planed maximum pressureload. Results indicate that a water pressure is acting on the concrete plug frominside the rock slot which was not assumed during the design. / I SKB:s Äspölaboratoriet har ett fullskaleförsök på en betongplugg, del av ett pluggsystemför förvaret av kärnavfall, utförts. Syftet med denna uppsats var attutvärdera betongpluggens beteende under fullskaleförsöket och hur det förhållersig till gjorda antaganden under dess utformning. Betongpluggen är kupolformad,oarmerad och platsgjuten med låg-pH-betong. Höga vatten- och svälltryck kommerverka på betongpluggen som är utformad för en livstid på 100 år. Under deförsta åren ska den även motverka läckage från insidan av deponeringstunneln. Innantrycklasten läggs på är det antaget att betongpluggen släpper från berget till följd avautogen krympning och kylning. Utrymmet mellan betongen och berget injekterasoch betongpluggen kommer således vara förspänd efter att kylningen upphört. Betongpluggen är analyserad med mätdata från fullskaleförsöket som jämförts medresultat från finita element analyser. Mätningarna inkluderar formtryck, inre töjningaroch temperaturer, deformationer i tunnelriktningen, deformationer relativt bergetoch lufttemperatur utanför betongpluggen. Två antaganden har gjorts under utvärderingen;att betongen är fast i berget eller att den är fri från berget. Resultaten jämförsäven med två liknande fullskaleförsök som utförts tidigare. Resultaten tyder på att betongpluggen till viss del släppt från berget innan injekteringen.Det är troligt att den släppt på vissa ställen och på andra inte. På grundav för högt vattenläckage där de ingjutna mätinstrumentens kabelgenomföring utförts,kunde inte betongpluggen belastas till det maximala tryck som var planerat.Resultaten tyder på att ett vattentryck verkar på betongpluggen mellan berget ochbetongen vilket inte var antaget under konstruktionen.

<p>There is a great need for accurate image reconstruction in the context of non-destructive evaluation. Major challenges include the ever-increasing necessity for high resolution reconstruction with limited scan and reconstruction time and thus fewer and noisier measurements. In this thesis, we leverage advanced Bayesian modeling of the physical measurement process and probabilistic prior information of the image distribution in order to yield higher image quality despite limited measurement time. We demonstrate in several ways efficient computational performance through the exploitation of more efficient memory access, optimized parametrization of the system model, and multi-pixel parallelization. We demonstrate that by building high-fidelity forward models that we can generate quantitatively reliable reconstructions despite very limited measurement data.</p> <p><br></p> <p>In the first chapter, we introduce an algorithm for estimating isotopic densities from neutron time-of-flight imaging data. Energy resolved neutron imaging (ERNI) is an advanced neutron radiography technique capable of non-destructively extracting spatial isotopic information within a given material. Energy-dependent radiography image sequences can be created by utilizing neutron time-of-flight techniques. In combination with uniquely characteristic isotopic neutron cross-section spectra, isotopic areal densities can be determined on a per-pixel basis, thus resulting in a set of areal density images for each isotope present in the sample. By preforming ERNI measurements over several rotational views, an isotope decomposed 3D computed tomography is possible. We demonstrate a method involving a robust and automated background estimation based on a linear programming formulation. The extremely high noise due to low count measurements is overcome using a sparse coding approach. It allows for a significant computation time improvement, from weeks to a few hours compared to existing neutron evaluation tools, enabling at the present stage a semi-quantitative, user-friendly routine application. </p> <p><br></p> <p>In the second chapter, we introduce the TRINIDI algorithm, a more refined algorithm for the same problem.</p> <p>Accurate reconstruction of 2D and 3D isotope densities is a desired capability with great potential impact in applications such as evaluation and development of next-generation nuclear fuels.</p> <p>Neutron time-of-flight (TOF) resonance imaging offers a potential approach by exploiting the characteristic neutron adsorption spectra of each isotope.</p> <p>However, it is a major challenge to compute quantitatively accurate images due to a variety of confounding effects such as severe Poisson noise, background scatter, beam non-uniformity, absorption non-linearity, and extended source pulse duration. We present the TRINIDI algorithm which is based on a two-step process in which we first estimate the neutron flux and background counts, and then reconstruct the areal densities of each isotope and pixel.</p> <p>Both components are based on the inversion of a forward model that accounts for the highly non-linear absorption, energy-dependent emission profile, and Poisson noise, while also modeling the substantial spatio-temporal variation of the background and flux. </p> <p>To do this, we formulate the non-linear inverse problem as two optimization problems that are solved in sequence.</p> <p>We demonstrate on both synthetic and measured data that TRINIDI can reconstruct quantitatively accurate 2D views of isotopic areal density that can then be reconstructed into quantitatively accurate 3D volumes of isotopic volumetric density.</p> <p><br></p> <p>In the third chapter, we introduce a separable forward model for cone-beam computed tomography (CT) that enables efficient computation of a Bayesian model-based reconstruction. Cone-beam CT is an attractive tool for many kinds of non-destructive evaluation (NDE). Model-based iterative reconstruction (MBIR) has been shown to improve reconstruction quality and reduce scan time. However, the computational burden and storage of the system matrix is challenging. In this paper we present a separable representation of the system matrix that can be completely stored in memory and accessed cache-efficiently. This is done by quantizing the voxel position for one of the separable subproblems. A parallelized algorithm, which we refer to as zipline update, is presented that speeds up the computation of the solution by about 50 to 100 times on 20 cores by updating groups of voxels together. The quality of the reconstruction and algorithmic scalability are demonstrated on real cone-beam CT data from an NDE application. We show that the reconstruction can be done from a sparse set of projection views while reducing artifacts visible in the conventional filtered back projection (FBP) reconstruction. We present qualitative results using a Markov Random Field (MRF) prior and a Plug-and-Play denoiser.</p>

When the low voltage electric grid is dimensioned electric loads are predicted by analyzing the area by certain factors such as geographical data, customer type, heating method etc. So far, the charging of Plugin Electric Vehicles (PEVs) is not considered as one of these factors. Approximately 30% of the distribution grid in Sweden is projected to need reinforcements due to the increased loads from PEVs during winters if the charging isn’t controlled. In addition to this Stockholm face the problem of capacity shortage from the transmission grid, limiting the flow of electricity into the city. This research is therefore conducted to analyze the impact that the increase of PEVs will have on the distribution grid in the future. This thesis simulates the electric grid for three substations located in Hammarby Sjöstad by using power flow analysis and electric grid data from 2016. To approach this problem a method to disaggregate the total power consumption per substation into power consumption responding to each building was developed. In addition to this the number of PEVs in the future was projected. Nine different scenarios were used to compare different outcomes for the future, namely the years of 2025 and 2040. In order to simulate the worst possible case for the electric grid all the PEVs were assumed to be charged at the same time, directly when arriving home on the Sunday when the power demand peaks in 2016. The results indicate that PEVs can have a considerable impact on the components of the low voltage distribution network and controlled charging should be implemented. By examining the impact on the simulated electric grid from the different scenarios the limit of PEV penetration is found. In the area of Hammarby this limit seems to be around 30 % of the total cars if there is no controlled charging. Without any controlled charging the peak power demand increases by 30% with a 30% share of PEVs, which is projected to happen in 2025. In 2040 when share of PEVs is projected to be about 95% the peak power is instead increased by more than 100% which shows the impact that PEVs can exert on the electric grid. Utilizing a simple method of controlled charging where the PEVs are instead charged during the night when the power demand is low, the peak power is not increased at all. This also results in the small cost benefit for PEV owners since the electricity is cheaper during the night and controlled charging can therefore save about 15% of the electricity charging cost. However, the main savings are for the grid owners since the need to reinforce the grid is heavily reduced. In addition to this the power losses are reduced heavily from about 14% down to 5% in the electric grid that is simulated. / När dimensioneringen av distributionsnätet utförs analyseras området genom att räkna med elektriska laster som till exempel kan bero på geografiska data, typ av konsument, uppvärmningsmetod etcetera. Än så länge har laddningen av elbilar (PEVs) inte varit en av dessa faktorer trots den förväntade tillväxten av elbilar. Ungefär 30% av Sveriges distributionsnät förväntas behöva förstärkningar på grund av den ökade elkonsumtionen från elbilar under vintrarna om laddningen inte kontrolleras. Utöver detta står Stockholm inför problemet med effektbrist från elöverföringsnätet. Denna uppsats genomförs således för att analysera påverkan från elbilar på fördelningsnätet i framtiden. Denna masteruppsats simulerar det elektriska nätet för tre nätstationer i Hammarby Sjöstad genom en analys av effektflödet. En metod för att disaggregera elkonsumtionen per nätstation ned till elkonsumtionen per byggnad utvecklades och antalet elbilar i framtiden uppskattades. För att utvärdera elbilars påverkan skapades nio olika scenarion för framtiden genom att undersöka hur det kommer att se ut år 2025 och år 2040. Genom att anta att laddningen av alla elbilar i området sker samtidigt, samma tid som den maximala förbrukningen av el sker under en söndag 2016, analyseras det värsta möjliga scenario för det elektriska nätet. Resultaten visar att elbilar kan ha enorm påverkan på de maximala lasterna för ett lågspänningsnät och därför kommer kontroll av laddningen behövas. Genom att undersöka elnätets påverkan i de olika scenariona uppskattades gränsen för hur många elbilar det modellerade elnätet klarar av. I Hammarby Sjöstad ligger denna gräns på ungefär 30% elbilar. Utan kontrollerad laddning ökar maxlasten med 30% år 2025 då antalet elbilar förväntas vara 30% av alla bilar i Hammarby Sjöstad. År 2040 då antalet elbilar uppnår ungefär 95 % av alla bilar ökar maxlasterna med mer än 100% vilket visar den enorma påverkan elbilar kan ha på elnätet. Genom att använda en simpel modell av kontrollerad laddning som består av att flytta laddningen från eftermiddagen till natten, då förbrukningen av elektricitet är låg, ökar inte maxlasten för dygnet alls jämfört med scenariot utan elbilar. Detta resulterar också i besparingen av elektricitetskostnad för elbilsägaren med cirka 15% eftersom elektriciteten ofta är billigare under natten jämfört med kvällens elpriser. Detta är dock små summor jämfört med besparingar elnätsägarna kan göra då elnätet inte behöver förstärkas lika mycket som skulle behövas utan kontroll av laddningen. Utöver detta så sänks även förlusterna av elektricitet i det simulerade nätet från 14% ned till 5% genom att utnyttja denna modell av kontrollerad laddning.

In dieser Arbeit werden versilberte Hochstrom-Steckverbindungen mit Kontaktelementen betrachtet, die in der Elektroenergieversorgung bei Belastung mit Fehlerströmen im Bereich von 24 µs bis 5 s eingesetzt werden. Am Flach- und Rundeinbau der Kontaktelemente werden Kurzschlussversuche im Bereich von (0,01…5) s durchgeführt. Der Kurzschlussstrom erwärmt die Steckverbindung und die Kontaktelemente innerhalb dieser Zeit auf mehrere 100 °C und führt zu einer thermisch aktivierten Schädigung. Dabei baut sich die Kontaktkraft durch Spannungsrelaxation zum Teil ab, und es kann zum Verschweißen der Mikrokontakte und Blasenbildung durch lokales Ablösen der Be-schichtung kommen. Bei einer zu starken Schädigung kann ein sicherer Betrieb der Steckverbindung nicht mehr si-chergestellt werden. Daher werden für die Mechanismen der Schädigung Grenzwerte festgelegt und eine maximale Belastung definiert. Ausgehend von den experimentellen Untersuchungen wird ein Berechnungsmodell auf Basis der Finiten-Elemente-Methode weiterentwickelt. Ein vereinfachtes Widerstandsmodell der Punktkontakte abhängig von Kontaktkraft und Kontakthärte bildet dabei das Verhalten der Mikrokontakte nach. Da das Verhalten der Kontakthärte bei starker Erwärmung im ms-Bereich nur unzureichend erforscht ist, werden aus Experimenten näherungsweise die benötigten Parameter bestimmt. Mit dem erweiterten Berechnungsmodell ist es möglich, die thermische Wirkung praktischer Kurzschlussversuche nachzubilden. Eine wesentliche Erkenntnis ist, dass die Höhe des Stoßstroms zu Beginn des Kurzschlusses einen entscheidenden Einfluss auf die maximale Erwärmung hat. Bei sehr hohen Stoßströmen am Anfang eines Kurzschlusses wird der Kontaktwiderstand stark reduziert. Für den weiteren Verlauf des Kurzschlusses entsteht in den Kontakten daher weniger Wärme, als wenn diese Reduktion nicht stattfindet. Das bedeutet, dass DC-Kurzschlüsse unter Umständen zu einer höheren thermischen Belastung und mechanischen Schädigung führen können als AC-Kurzschlüsse mit gleichem Effektivwert. Experimente bestätigen diese Theorie. Dies gilt allerdings nur, wenn der Stoßstrom nicht zum sofortigen Verschweißen der Kontakte führt. Anhand der Erkenntnisse aus den Experimenten und Berechnungen werden Empfehlungen für die Auslegung und die Prüfung von Hochstrom-Steckverbindungen gegeben. Es zeigte sich, dass das für Prüfungen oft verwendete I2t-Kriterium bei Steckverbindungen nur sehr eingeschränkt anwendbar ist. Die Kurzschlussdauer kann damit nur um ca. (13…17) % verändert werden, ohne dass sich die Beanspruchung in der Prüfung unzulässig ändert. Alternativ schlägt die Arbeit das Ixt-Kriterium vor. Dieses lässt es bei bekannter Geometrie der Steckverbindung zu, einen Prüfstroms in einem vielfach größeren Zeitbereich einzustellen und erzeugt dabei eine vergleichbare thermische Beanspruchung oder mechanische Schädigung. Ein Erwärmen der Steckverbindung auf die maximal zulässige Betriebstemperatur vor dem Kurzschluss, was bei-spielsweise bei einem Fehler im realen Betrieb stattfinden kann, hat einen vergleichsweise geringeren Einfluss auf die Erwärmung und die mechanische Schädigung. Hintergrund ist, dass die Vorerwärmung zu einer Reduktion der Kon-takthärte führt und damit große Kontaktflächen erzeugt, die einen geringen Kontaktwiderstand haben. Hierdurch entsteht weniger Verlustleistung, was die Erwärmung der Steckverbindung reduziert. Aus den gewonnen Erkenntnissen werden Empfehlungen für die Auslegung, Prüfung und die Modellierung des Kurz-schlussverhaltens von Steckverbindungen mit Kontaktelementen für die Elektroenergieversorgung abgeleitet. / In this thesis, silver plated plug-in connectors for electrical power supply under short time current load are investigat-ed. The duration of the short time or short circuit current load is between 24 µs and 5 s. Both flat and round model plug-in connectors are stressed with the short time current. This current heats the plug and socket as well as the contact elements by several hundred Kelvin, which can lead to thermally induced damages. These may include a reduction of the contact force, welding of the contact points and blistering of the coating. If the damage is too severe, safe operation at the rated continuous current may not be able after the short circuit. Thus, limiting loads are defined which ensure a safe operation. Based on the experiments, a finite element model is refined. A simplified model of contact points is used to imple-ment the contact behaviour. This model implements the overtemperature in the contacts, the contact hardness and the contact force into the calculation. In fact, few data for load in the range of milliseconds are available on this matter. Hence, experiments are used for an approximation of the required parameters. The refined model allows for a good correlation between experiments and calculated data. A key finding is that the magnitude of peak current at the beginning of the short circuit has a decisive influence on the maximum heating. In case of a very high peak current at the beginning of a short circuit, the contact resistance is greatly reduced. For the further course of the short-circuit, therefore, less heat is generated in the contacts than if this reduction did not take place. This means that DC short circuits can under certain circumstances lead to higher thermal stress and mechanical damage than AC short circuits with the same RMS value. This is only valid if the peak current does not heat the contact points up to their welding temperature. Experiments confirm this theory. Recommendations for the dimensioning and testing of high current connectors are given on the basis of the experi-ments and the calculations. It was shown that the I²t-criterion, which is often used for altering the test duration in recommended standards, can only be applied to a very limited extent. The short circuit duration can only be changed by about (13…17) % or otherwise the severity of the mechanical damage is likely to change as well. As an alternative, it is proposed to use the newly introduced Ixt-criterion. If the geometry of the connector is known, this criterion allows alternating the short circuit duration in a broader range without major changes in the severity of the test. In a real world application, short circuits may occur while the connectors are under heavy load, which means that at the beginning of the short time current, the connector is preheated. Tests showed that this has only a minor impact on the temperature rise and the mechanical damage of the contact elements. The reason for this behaviour is that, due to the preheating, the hardness of the contact material drops and the contact area is enlarged. This results in a comparatively lower contact resistance and less power loss is generated. This reduces the influence of the higher start-ing temperatures to a certain degree. On the basis of the findings, recommendations are derived for the design, testing and modelling of the short-circuit behaviour of connectors with contact elements for electrical power supply.

No description available.

No description available.

In a bus chassis, welded connections are often preferred to other fastening techniques due to low cost and broad competence among suppliers but are usually the weakest parts due to fatigue life. Evaluation of welds is often costly in time and competence. Long iteration times are often leaving welded designs unoptimized and poorly understood by designers and engineers. The goal of this thesis is to gather knowledge about a plug-welded bracket commonly found welded to beams in bus chassis and body, aiding the design and dimensioning of such brackets. A factorial design study was performed using FEM analysis with the “Effective notch method,” revealing the effects of seven different design parameters on the stresses in the weld. A theory to analytically calculate the profile of the bracket is presented. The theory is taking the beam’s second moment of area and the bending moment into consideration, essentially tuning the bracket’s stiffness to the beam and the load situation. An improved bracket is presented, analyzed, and compared to the design study. The results show how stresses in the weld are affected by the stiffness of the bend in the bracket, the location of bolts (or other fastening technique) and the plug weld dimensions. When the weld is made to run longer along the beam, the importance of adjusting the stiffness in the bracket increases in order to balance the load throughout the whole weld. / Svetsade fästelement är ofta att föredra i ett busschassi över andra tekniker av kostnadsskäl och att en bred kompetens finns inom svets hos många underleverantörer. Men på grund av utmattning är ofta svetsade infästningar den svagaste punkten i ett chassi. Utvärdering av svetsar är kostsamt i tid och kompetens. Långa iterationstider i svetsutvärderingar lämnar ofta svetsen ooptimerad och undermåligt förstådd av designers och ingenjörer. Målet med detta arbete är att samla kunskap runt ett pluggsvetsat fästelement som ofta förekommer i busschassier och busskarosser, för att underlätta design och dimensionering av dessa fästelement. En faktoriell designstudie var utförd med FEM analys enligt ”Effective Notch” metoden för att undersöka effekten från sju olika designparametrar på spänningskoncentrationerna i svetsen. En teori för att analytiskt beräkna profilen på fästelementet presenteras. Teorin tar balkens böjtröghetsmoment och böjmoment med i beräkningen för att optimera fästelementets styvhet till balken och lastsituationen. Ett förbättrat fästelement är presenterat, analyserat och jämförd med designstudien. Resultaten visar hur spänningarna i svetsen påverkas av styvheten i den böjda delen av fästelementet, placeringen av bultar (eller annan infästningsteknik) och dimensioner på ”svetspluggen.” När svetsen är går längre längs med balken blir fästelementets styvhet allt viktigare för att kunna balansera lasten igenom det svetsade området.