Heavy metals are metallic elements with a density of at least 5 g/cm^3. Some heavy metals exist in nature and within organisms naturally, but many heavy metals are poisonous at low concentrations and the amount of heavy metals in nature has increased because of human activity, both in water and on land. X-ray fluorescence is a suitable method to measure heavy metals. X-ray fluorescence, or XRF as its abbreviated, is a measurement method that uses fluorescent x-ray radiation from elements to identify and quantify. Mitt University in Sundsvall has an x-ray lab that has a portable x-ray fluorescence instrument that has been used to conduct measurements. The samples have been sea water and bottom sediment from three different areas in Gävlebukten. One of the areas had multiple big industries nearby, one was next to the city and one on the countryside. This work shows that usage of a portable XRF instrument to measure heavy metals in sediment produces a good result. Multiple metals were detected and one sample contained mercury in a high concentration. Measurements of sea water had too low signal to noise ratio to show any presence of heavy metals in all but one sample. This assumes to be because of waters interaction with x-ray radiation in combination with the low concentration of the metals and that a too short measurement time was used.

Industrial Control Systems (ICS) running in a virtualised environment are be-coming a common practice, however, there is not any standard or specification detailing authentication methods for industrial environments.Considering the current standards and specifications designed to provide au-thentication, we present the design and implementation of several approaches that enable trusted computing in virtualised environments. Most of the ap-proaches are based on a hardware-based root of trust, assuring the user’s soft-ware is always running on the same workstation.After comparing the approaches, we test an efficient approach by using the SecDevID stored in the virtual TPM to establish TLS sessions. Given the TLS features, this approach provides both hardware and VM authentication as well as confidentiality. Finally, the performance of the tested approach is evaluated. / Industriella styrsystem (ICS) som körs i en virtualiserad miljöo blir allt vanligare, men det finns hittils ingen standard eller specifikatjon för autentiseringsmetoder i industriella miljöer. Baserad på de gällande normer och specifikationer för att genomföra autentisering, vi presenterar design och implementation av flera metoder som möjliggör trusted computing i virtualiserade miljöer. De flesta av de metoder är baserade på en hårdvarubaserad ankare av förtroende, som garanterar att användarens mjukvara alltid körs på samma hårdvara. Vi jämför olika metoder, och testar en effektiv metod som avnänder SecDevID lagrad i en virtuell TPM för att etablera TLS förbindelser. Tillsammans med TLS ger lösningen autentisering för både hårdvara och VM, samt konfidentiletät. Vi utvärderar prestandan av den sistnämda metoden genom ett expertiment.

The climate crisis is more prevalent today than ever before. Many see a clean, carbonfree, electrification as a must if we are to turn this challenge around. Because more andmore of society runs on electricity there has never been a bigger need for an efficientpower grid.Huge amount of data are gathered from the grid every day and this data holds a lotof information that could help to optimise the power grid. This thesis aimed at investigating how consumption data could be used to understand consumption behaviourswithin the power grid and to try and capture these behaviours with typical customers.Consumption data comes in the form of a time series. In every Swedish house therewill soon be a electricity meter that measures the consumption of the house each hour.This creates a time series of consumption with 24 data points each day. One common,typical behaviour, within the power grid is a peak in consumption during the morninghours when everyone is preparing for work and one in the evening when customers startto arrive home and starts to prepare dinner.The data used in this thesis were based on a geographically restricted area, aroundUppsala, with customers in separate houses and a fuse size of 16 A, 20 A or 25 A. Theanalysed data set held 13997 of Vattenfall Eldistribution customers.One group of customers that are particularly interesting are those that owns an electricvehicle (EV). This is because the charging of the vehicle can be done at power muchlarger than what a normal separate house draws from the grid. In an attempt to gatherinformation about EV owners charging habits, a questionnaire were created and postedto different Swedish EV forums. In total 44 EV owners answered the questionnaire.The method applied in this thesis works by grouping customers based on attributescalculated from the time series of the customers. The attributes calculated within thisthesis were degree of utilization, utilization time, night timeshare of consumption, correlation with aggregated load, correlation with air temperature and load factor. Eachattribute are calculated for winter and summer separately. The k-Mean algorithm isutilised to cluster the customers into ten cluster based on the attributes. The time series of each customer is then scaled down using their daily max and min consumption.Then the correlation between three different percentiles of the time series data of eachcluster are calculated. If the correlation factor is high enough the cluster is said to holdcustomer that consumes according to the pattern described by the 57.5th percentile.Next the correlation between the representative curves of each cluster is calculated toensure that only unique patterns are saved as a typical customer. If the representativecustomer of two clusters show high correlation, they are combined into a new largergroup.iA set of typical customers based on degree of utilization, load factor, correlation andall three combined were created. The results indicate that customers with a low degreeof utilization and a high load factor have a flatter consumption profile. Customers thathave high correlation with aggregated load should be prioritised since they contributemore to the aggregated peak load.Using information from Trafikverket, 68 customers were identified within the original data set as being EV owners. This made it possible to analyse the time series tofind information about their charging behaviour. To find charging events, consecutivehours were analysed to find hours with a difference in consumption of at least 3.7 kWh.Of the 68 analysed, 39 showed more than 20 charging events during 2020. The mostpopular starting time for charging were 16 o’clock and the most common duration werebetween one and four hours.The method used in this thesis creates typical customers that illustrates a commonconsumption profile of customers within a group. If a typical customer that illustratesconsumption values are desired the customers has to be grouped based on some attributethat describes the amount of electricity that they consume. Creating the typical customers with a smaller sample of customer from the group creates a typical curve thatexhibits more of the randomness that characterises the real consumption profiles.

In electrical devices and integrated circuits, ohmic contacts are necessary and a prerequisite for the current transport over the metal-semiconductor junctions. At the same time, a desired property of the ohmic contacts is to not add resistance or in other way disturb the performance. For high temperature electronics, the material demands are high regarding functionality and stability at elevated working temperatures, during and after temperature cycling and during long time of use.  Silicon carbide, SiC, is a suitable substrate material for fabrication of high temperature electronics with a large band gap, good thermal conductivity and chemical inertness. The large bandgap causes however difficulties in finding a common material for ohmic contacts to both n- and p-type SiC. The goal of this project is to find a suitable metallization for n- as well as p-type contacts to epitaxially doped SiC for use in integrated circuits. The circuit technology developed and used in KTH for SiC is built on bipolar junction transistors. The p-doped base layer in the transistors is relatively low doped; 5 x 1017 – 1 x 1018 cm-3. P-type SiC is more difficult to form ohmic contacts to than n-type SiC, with such a low doping concentration it is even more complicated.  Today, the metallizations used in the contacts consists of Ni for n-type contacts and Ni/Ti/Al to p-type SiC. Experiments of the specific contact resistivity ρc and the sheet resistance Rsh of these contacts, characterized to two types of samples, are presented for the extreme temperature range of -40 °C – 500 °C. Ohmic contact test chips with transfer length method structures have been compared to similar test structures on samples from the KTH SiC integrated circuits. The metals were also tested on the opposite doping polarity.  Sputter deposition of Co and Si in layers to form CoSi2 contacts was made to chips from the same contact test wafer for comparison with the behavior of the presently used contacts. Since this was a new metallization, the process development of the high temperature anneal and contact formation made an important part of the work.  Out of the tested contacts, Ni has been the best for n-SiC and Ni/Ti/Al for p-SiC. None of the three metallizations formed ohmic contacts to both n- and p-SiC. However, the CoSi2 contacts showed specific contact resistivity ρc &lt;4 x 10-6 Ωcm2 at 25 °C and non-linear I-V characteristics but without barriers to p-SiC after voltage sweeps of ± 75V. / <p>QC 20141203</p>

The electricity distribution in Sweden is experiencing aconsiderable change in conditions by the radical change inregulation policy. The Swedish Energy Agency(Energimyndigheten) is introducing a new regulatory model, theNetwork Performance Assessment Model, as the main tool forsupervising the natural monopolies of local electricitydistribution. The new model has interesting and far-reachingconsequences for the involved parties. This thesis investigates the implications of the newregulation and the regulatory tool, in particularly related toIT-investments evaluations in the distribution utilities. Intoday’s utilities, IT-systems are often a vital part ofoperations, ranging from e.g. real-time monitoring andcontrolling of the network to various administrative tasks.Considerable amounts of money are spent on investments toenhance and maintain these IT-systems. The changed regulationand the new regulatory model put a focus, more than ever, onefficient use of utilities’resources, implying a need forsuitable methods to evaluate ITinvestments. In the thesis, the new regulation is described, inparticular the new regulatory model. The model is presented andcentral implications are identified, e.g. in terms of newrequirements put on the utilities and general businessconsequences. As stated, the focus is on implications relatedto IT-systems and investments in these systems. Furthermore, a wide range of IT-investment evaluationmethods are presented and categorized in the thesis, focusingon IT-investment appraisal techniques. The categories rangesfrom methods only considering cash flows of investments to moreelaborate methods, e.g. for considering behavioral sciencesaspects. The thesis outlines and presents categories of methodsas well as examples of individual methods. In the final part of the thesis, suitable IT-investmentevaluation methods, given the implications of the newregulation, are discussed. The implications include both directbusiness related aspects as well as more technical issuesrelated to the IT-investments. It is also concluded that asuitable method need to incorporate both monetary consequencesof the investment as well as a limited number of non-monetary,related to the regulatory model. Key words:Regulation of electricity distribution,IT-investment evaluation methods, Implications of monopolyregulation / QC 20100608

The vertical-cavity surface-emitting laser (VCSEL) is a type of laser diode that emits light from the surface of the chip from which it is manufactured rather than from a cleaved edge as so far has been common for most telecommunication lasers. VCSEL’s low cost, high power efficiency and low power consumption properties make it a very attractive signal source for many applications such as fiber optical communication, optical interconnects, 3D sensing, absorption spectroscopy, laser printing, etc. In this work, we have developed and evaluated new designs and technologies for extending the performance of VCSELs based on the GaAs material system. A novel scheme for single-mode emission from large size VCSELs, with active region size up to 10 μm, is proposed and discussed. Oxide-free designs of the VCSEL structure either based on an epitaxially regrown p-n-p layer or a buried tunnel junction (BTJ) for lateral current confinement are fabricated and characterized; the latter scheme yielding significant dynamic and static performance improvement as compared to epitaxially regrown design. In addition, the first room-temperature operation of a heterojunction bipolar transistor (HBT) 980nm VCSEL, a so-called transistor-VCSEL, is demonstrated. This novel three-terminal operational VCSEL is believed to have the potential for a ultrahigh modulation bandwidth due to altered carrier dynamics in the cavity region. / <p>QC 20140612</p>

Power systems are in a phase of automation where intelligent components and sub-systems are employed to monitor, control and manage the grid. Quantifying the complex consequences on system reliability, from the integration of such automated and semi-automated equipment into the existing grid is important for maintenance optimisation and fault mitigation. This thesis identifies the  advanced approaches in power system reliability analysis with the potential to capture the complications and correlations in modern power grid after reviewing the traditional reliability evaluation methods. A method for modelling the different modes of failures, possible in a substation and feeder architecture along with the probable false tripping scenarios was developed. An improved Reliability Block Diagram based approach was designed to count in the traditionally unaccounted failure cases affecting both the primary grid and the protectionand control equipment. The effect and corresponding trend of additional feeder lines in a radial distribution system on the net interruption rate experienced at load ends of feeders are derived and modelled. Such real-world substation architectures are analysed and the aforementioned trends are compared with those from the practical grid. Thus, the analysis was able to identify and measure the complex hidden failure probabilities due to both unwanted operation of breakers and functional failure of protection systems. The measured probabilities were used to calculate the impact of protection and control equipment on system  reliability. The obtained results were verified by comparing it with the observations by energy researchers on ten years of protection system failure statistics. The application of the model and results, in optimal maintenance planning and power network optimisation are identified as the next step. / <p>QC 20151002</p>

The use of dielectric resonator filters is very common in the telecommunications industry for applications with demanding filtering requirements. For high power applications in particular, TE01-mode dielectric resonators are often used because of its low losses and excellent peak power handling capabilities. The essence of this work is to great extent focused around the fact that even a small amount of dissipated power can give rise to a large temperature increase if the heat transfer is insufficient. A temperature increase due to self-heating translates into a degradation of filter performance. Understanding the mechanisms behind this degradation is vital in order to compensate for these effects. Computer simulations can successfully be used to characterise the electrical and thermal behaviour of these devices. However, if the filter in question is not properly tuned when running the analysis the results will bring little or no value. This work outlines an efficient filter design flow based on Port Tuning in order to overcome this tuning issue. By carefully studying both a single resonator and a realistic filter example using CFD analysis the heat transfer mechanisms can be quantified and the dominant terms can be identified. Based on these results, a simplified model for the thermal analysis can then be established. A coupled analysis including electromagnetic, thermal and structural analysis is then demonstrated that predicts the performance degradation of the filter response. It is also demonstrated how these effects can be compensated for. / Inom telekomindustrin är dielektriska resonatorer vanligt förekommande i filtertillämpningar med krävande prestanda. För högeffekttillampningar i synnerhet används ofta TE01-mod resonatorer på grund av sina låga förluster och utmärkta effekttålighet. Kärnan i detta arbete kretsar kring det faktum att även små effektförluster kan leda till stora temperaturförandringar om värmetransporten är otillräcklig. En sådan temperaturökning på grund av egenuppvarmning yttrar sig i termer av en församring av filterprestandan. En förståelse för mekanismerna bakom denna prestandaförsamring är nödvandig for att lyckas kompensera bort dessa effekter. Datorsimuleringar kan framgångsrikt användas för att karraktärisera dessa komponenter såväl elektriskt som termiskt. Om filtret i fråga däremot inte är trimmat i simuleringen blir värdet av analysen begränsat eller rent av obefintligt. I detta arbete presenteras en effektiv designmetodik baserat på Port Tuning som överbryggar denna trimproblematik. Genom att sedan noggrant studera en ensam resonator och ett mer realistiskt filterexempel med hjälp av CFDanalys kan mekanismerna bakom värmeledningen kvantifieras och de dominerande termerna identifieras. Baserat på dessa resultat kan sedan en förenklad modell för den termiska analysen byggas. Det kan sedan visas hur en kopplad elektromagnetisk-, termisk- och strukturmekanisk analys kan användas fär att prediktera försämringarna av filter-responsen. Det visas också hur dessa effekter sedan kan kompenseras bort.

Speech enhancement systems achieving a joint suppression of reverberation and background noise can be used in digital hearing aids, voice controlled systems or hands-free telephony. Demanding requirements for computational complexity, signal delay and speech quality must be fulfilled in order to achieve a satisfactory performance. The speech quality depends on how accurate the reverberation characteristics such as the reverberation time or the spectral variance of the late reverberant speech are estimated. In this thesis, an efficient algorithm for a blind reverberation time estimation based on maximum likelihood approach is introduced. The new algorithm allows to estimate reverberation times from a much wider range with acceptable accuracy. Variance of the late reverberant speech is another important quantity in dereverberation systems. Two late reverberant spectral variance estimation methods are compared with regard to estimation accuracy and computational complexity. Finally, the performance of the considered speech enhancement system is analyzed with the improved reverberation time estimator.

In modern trucks there is a number of control units, which tasks are varying; control of the engine, brakes, gearbox, etc. In order to ensure that these devices work properly, they must be thoroughly tested under normal conditions but also when they are exposed to stresses such as electrical faults (short circuit, breaks, etc.). A breakout box, BOB, is a type of test equipment used to stress test a controller by inducing electrical fault on its cables. It is done manually and is time consuming. The aim of this thesis is to develop an ABOB (Automated BreakOut Box). It should be placed in the driver's cab. It was designed in three different versions. Electrical faults are simulated. They along with a test program verify that no serious events occur for the vehicle. Literature studies of earlier works with automated electrical faults were made initially as a background for the selection of the automation method. The faults that have been implemented for the prototype of the ABOB is short circuit with di_erent supply voltages (including earth) and breakage. This report describes the development from a simple functional model to prototype with a focus on the hardware. The ABOB can run automatically without human interaction except at boot time. The ignition needs only to be switched on and the device can work in the evening and at night. The results were that the implemented ABOB could simulate the given electrical faults with verification. The automation method proved feasible. The work has been done in cooperation with Anna Bladh. This report takes up the hardware of the prototype for the three versions. Anna's report describes the software in the System design of automated test equipment for electrical control units into trucks. / I moderna lastbilar sitter ett flertal styrenheter, vars uppgifter varierar; styrning av motor, bromsar, växellåda osv. För att säkra att dessa enheter fungerar som de ska måste de testas noggrant - dels under normala förhållanden men också då de utsätts för påfrestningar såsom elektriska fel (kortslutning, avbrott osv.). En breakout box, BOB, ar en typ av testutrustning som används för att stress testa en styrenhet genom att inducera elektriska fel på dess kablage. Det görs manuellt och ar tidskrävande. Syftet med det här examensarbetet är att ta fram en ABOB (Automatiserad BreakOut Box). Den ska placeras i förarhytten. Under arbetets gång designades ABOB:en i tre olika utföranden. Elektriska fel simuleras. De tillsammans med ett här framtaget testprogram verifierar att inga händelser inträffar för fordonet. Litteraturstudier av tidigare arbeten med automatiserade elektriska fel gjordes inledningsvis som bakgrund för valet av automatiseringsmetod. Felen som har implementerats för ABOB-prototypen ar kortslutning med annan matningsspänning (inklusive jord) och avbrott. Denna rapport beskriver utvecklingen från en enkel funktionsmodell till färdig prototyp med fokus på hårdvaran. ABOB:n kan köras automatiskt utan att tillsyn erfordras utom vid uppstarten. Tändningen behöver bara slas på och enheten kan arbeta kvälls- och nattetid. Resultaten blev att den implementerade ABOB:en kunde simulera de givna elektriska felen med verifiering. Den framtagna automatiseringsmetoden visade sig genomförbar. Arbetet har skett i samarbete med Anna Bladh. Den här rapporten tar upp prototypens hårdvara för de tre versionerna. Annas rapport beskriver mjukvaran i System design of automated test equipment for electrical control units in trucks.