Observability Analysis for Large-Scale Power Systems Using Factor Graphs

The state estimation algorithm estimates the values of the state variables based on the measurement model described as the system of equations. Prior to applying the state estimation algorithm, the existence and uniqueness of the solution of the underlying system of equations is determined through the observability analysis. If a unique solution does not exist, the observability analysis defines observable islands and further defines an additional set of equations (measurements) needed to determine a unique solution. For the first time, we utilise factor graphs and Gaussian belief propagation algorithm to define a novel observability analysis approach. The observable islands and placement of measurements to restore observability are identified by following the evolution of variances across the iterations of the Gaussian belief propagation algorithm over the factor graph. Due to sparsity of the underlying power network, the resulting method has the linear computational complexity (assuming a constant number of iterations) making it particularly suitable for solving large-scale systems. The method can be flexibly matched to distributed computational resources, allowing for determination of observable islands and observability restoration in a distributed fashion. Finally, we discuss performances of the proposed observability analysis using power systems whose size ranges between 1354 and 70000 buses.Comment: 9 pages, 9 figure, version of the journal paper submitted for publicatio

EU Common Foreign and Security Policy and Bosnia and Herzegovina

The beginning of modern history and the subsequent war in Bosnia and Herzegovina coincide with the institutional beginnings of the European Union common foreign and security policy. At that time, Europe did not have a single position, nor could it have achieved a political consensus on any issue. In addition, it lacked appropriate instruments, as well as readiness and willingness to actively engage to put an end to war in BiH. The war in BiH was stopped, however, thanks to the efforts of the United States. This was a crucial moment for Europe to modify its common foreign and security policy. The European Union has passed a thorny path of establishing common foreign and security policy. On this path, however, the EU has experienced some progress and achieved good results, although not sufficient, just as BiH has made some progress in reforms. In order for BiH to joint the family of modern democratic countries, it will need a stronger engagement of the European Union and its more decisive common foreign and security policy, because only together we can cope with global challenges. Peace and prosperity in Bosnia and Herzegovina will also help build free and stable Europe

Distributed Inference over Linear Models using Alternating Gaussian Belief Propagation

We consider the problem of maximum likelihood estimation in linear models represented by factor graphs and solved via the Gaussian belief propagation algorithm. Motivated by massive internet of things (IoT) networks and edge computing, we set the above problem in a clustered scenario, where the factor graph is divided into clusters and assigned for processing in a distributed fashion across a number of edge computing nodes. For these scenarios, we show that an alternating Gaussian belief propagation (AGBP) algorithm that alternates between inter- and intra-cluster iterations, demonstrates superior performance in terms of convergence properties compared to the existing solutions in the literature. We present a comprehensive framework and introduce appropriate metrics to analyse AGBP algorithm across a wide range of linear models characterised by symmetric and non-symmetric, square, and rectangular matrices. We extend the analysis to the case of dynamic linear models by introducing dynamic arrival of new data over time. Using a combination of analytical and extensive numerical results, we show the efficiency and scalability of AGBP algorithm, making it a suitable solution for large-scale inference in massive IoT networks.Comment: 14 pages, 18 figure

Applying the response surface methodology to predict the energy retrofit performance of the TABULA residential building stock

Recent advances in computing software have enabled the development of calibrated building energy simulations tools that allow retrofit-related analysis including optimization and energy-efficient building design. However, to create a national energy and climate plan, using these tools may imply a great deal of effort (time, cost, and human resources) to carry out simulations for the full set of different building types, construction, geometries, design parameters, and retrofit scenarios. Because of this, simplified approaches that can reliably estimate the impact of energy-efficiency retrofit alternatives based on averaged building stock characteristics could offer a significant advantage, especially in middle-income countries such as Bosnia and Herzegovina. This study aims to explore the energy reduction potential of a representative building from the national residential building stock by utilizing the response surface methodology (RSM). In this study, RSM is combined with the energy simulation tools EnergyPlus and DesignBuilder to model the energy savings associated with energy-efficient retrofit measures for a residential building from the national TABULA registry in Bosnia and Herzegovina. This study introduces a novel energy consumption model that can be applied to optimize energy-efficient retrofit design solutions for reducing the energy consumption for heating and cooling in the residential building sector. Moreover, the model developed was validated by using the results of a national survey on energy consumption in Bosnia and Herzegovina. Therefore, the use of the model developed is versatile and suitable for rapid prediction of energy-efficient retrofit-related energy consumption and energy savings of the residential building stock

EXPOSURE OF NURSES TO MERCURY FROM BROKEN MEDICAL EQUIPMENT

Živa je toksični metal s negativnim zdravstvenim učincima na čovjeka. Unatoč toj činjenici, živa se i nadalje primjenjuje u različitim medicinskim uređajima i proizvodima kao što su toplomjeri, tlakomjeri i u laboratorijima. Tijekom 2009. godine provedeno je istraživanje u kliničkoj bolnici u Zagrebu o procjeni uporabe živinih mjernih instrumenata, toplomjera i tlakomjera te postojanju moguće profesionalne izloženosti medicinskih sestara živi. Upitnik sastavljen od pitanja o poznavanju toksičnosti žive i utjecaju na zdravlje, rukovanju živinim mjernim uređajima i mogućoj izloženosti iz razbijenih uređaja, zbrinjavanju razbijenih uređaja i sklonostima vezanim uz uporabu živinih ili elektronskih mjernih uređaja ispunila je 31 medicinska sestra s različitih bolničkih odjela. Sve medicinske sestre uključene u istraživanje smatraju da su izložene živi iz razbijenih mjernih instrumenata tijekom obavljanja radnih aktivnosti i svjesne su njezine toksičnosti. Medicinske sestre daju prednost uporabi živinih mjernih uređaja u odnosu na elektronske jer smatraju da su živini uređaji precizniji i pouzdaniji iako je vrijeme mjerenja dulje, smatraju da nisu dovoljno educirane o uporabi elektronskih uređaja i njihovom održavanju te da bi u slučaju kvara nedostajala tehnička potpora. Zdravlje i sigurnost na radnom mjestu istovremeno utječu i na zaposlenike i na poslodavca. Implementacija zaštite na radu utvrđena je zakonom u mnogim zemljama. Kako bi se unaprijedili zdravstveni uvjeti na radnom mjestu, sve bolnice u Hrvatskoj trebaju provoditi procedure i pratiti smjernice za zaštitu radnika i poslodavaca. Rezultati istraživanja upućuju na potrebu daljnjih praćenja profesionalne izloženosti medicinskih sestara živi iz mjernih uređaja koji sadrže živu.SUMMARY: Mercury is a metal toxic to humans. In spite of these known facts and adverse health effects, mercury continues to be used in various medical devices such as thermometers and sphygmomanometers, and in laboratories. During 2009, a survey was conducted at the University Hospital in Zagreb, Croatia, in order to estimate the possibility of occupational mercury exposure among hospital nurses using mercury-based medical equipment (thermometers and sphygmomanometers). Thirty one nurses working in different hospital wards were interviewed on their familiarity with the facts concerning mercury toxicity, on the handling of and exposure to broken mercury-based medical equipment and on their preferences regarding the use of certain equipment type, i.e. mercury-based or electronically operated. It was found that all interviewed hospital nurses are exposed to mercury from broken equipment and all are aware of its toxicity. Nevertheless, most prefer mercury-based equipment over electronically operated one because it is more precise and accurate, and because of the lack of technical support and education in the maintenance of electronic equipment. Health and safety at work are issues affecting both employers and employees regardless of professional background. Nowadays, the implementation of an occupational health and safety system is a requirement imposed by law in many countries. To improve health conditions at work, all hospitals in Croatia should implement procedures and follow guidelines for worker and employer protection. The results of the survey indicate that future research on occupational mercury exposure among hospital nurses using mercury-based medical equipment is “a must”

Født trygda? Betydningen av sosial klasse for mottak av uføretrygd og AAP som ung

De siste 15 årene har andelen unge mottakere av uføretrygd doblet seg. Dette medfører store samfunnsøkonomiske kostnader, både for det offentlige og for personene det gjelder. I 2019 ble folketrygdens totale utgifter for Arbeids- og sosialdepartementet antatt å være på rundt 425 milliarder kroner, en økning på rundt 8,5 milliarder kroner fra budsjettet i 2018. I tillegg følger sosiale kostnader for de unge uføre i form av stigma knyttet til det å stå utenfor arbeidslivet. Blant de som mottok uføretrygd ved utgangen av juni 2015, hadde 35% en psykisk lidelse. Årsaken til den stadig økende andelen unge uføre synes å være kompleks. Foreliggende studier peker på årsaker som regulatoriske endringer i NAV, endret diagnosepraksis, samt strukturelle endringer i arbeidsmarkedet som gjør det vanskeligere for psykisk syke å stå i arbeid. I denne oppgaven vender jeg blikket mot betydningen av sosial klasse som potensiell årsaksfaktor. Ved˚a bruke en konstruert variabel som m˚aler foreldrenes inntektsrang, studerer jeg sammenhengen mellom sosial klasse og uførhet blant kohortene født i 1989, 1990 og 1991. På samme måte som i Markussen og Røed (2019) er variabelen er konstruert med den hensikt at den skal minimere risikoen knyttet til livssyklusskjevhet, og at den skal ha konstante marginalfordelinger for hvert kull. Med grunnlag i registerdata og opplysninger fra kontroll- og utbetaling av helserefusjoner (KUHR), estimerer jeg effekten av sosial klasse på sannsynligheten for å motta uføretrygd eller AAP som ung. For en mer detaljert tilnærming presenterer jeg tre mulige mekanismer sosial klasse kan påvirke uførhet gjennom: psykiske lidelser, fullføring av videregående skole og arbeid eller fullført bachelor. I analysen finner jeg at sosial klasse øker sannsynligheten for å bli ufør og for å utvikle en psykisk lidelse, og reduserer sannsynligheten for å fullføre videregående og være i arbeid eller ha en bachelorgrad. Deretter studerer jeg utviklingen i den intergenerasjonelle mobiliteten i Norge for kohortene født mellom 1974-1997. Ved å studere utviklingen i den sosiale gradienten for de nevnte økonomiske utfallene, finner jeg at betydningen av sosial klasse har økt over tid. I tråd med Markussen og Røed (2019) tyder funnene på at det er barn og unge tilhørende de laveste klassene som faller bakpå når det gjelder en rekke utfall, inkludert uføretrygd og AAP. Jeg konkluderer med at det må rettes tiltak som øker fullføring av videregående utdanning blant de som tilhører de laveste inntektsklassene for å kunne reversere den negative utviklingen

War Tunnel-Museum in Sarajevo

Abweichender Titel laut Übersetzung der Verfasserin/des VerfassersLiteraturverz. S. 155Die Belagerung von Sarajevo war mit der Dauer von 1.425 Tagen die längste Belagerung einer Stadt im 20. Jahrhundert. Diese tragische Geschichte soll durch den Bau des Museums für Wahrheit, Erinnerung und Menschlichkeit bewahrt werden. Der Ort für dieses Museum ist der "Sarajevo Tunnel des Lebens", der damals als Fluchtttunnel der einzige Ausweg aus der Stadt war und heute ein Denkmal ist.The Siege of Sarajevo that lasted for 1,425 days, is the longest siege of a city in the 20th century. This tragic story should be preserved for truth, memory and humanity through construction of the museum. The location of this museum is the "Sarajevo Tunnel of Life", that was the escape tunnel as the only way out of the city and today is a monument. The museum "Sarajevo Tunnel of Life" is based on the concept of contrasts. The contrast between closure and openness, darkness and light, life and death. The architecture of the museum tells the story of the emotions of the siege, the experience of the flight and passes this story on next generations.15

Real-time updates of user interfaces for embedded systems : Update user interfaces in real-time with MQTT and websockets

Dagens webbläsare uppdaterar sitt utseende mer än någonsin och att kunna utföra det på ett effektivt sätt är essentiellt. Att kompilera om en hemsida och ladda upp den på nytt är ineffektivt och framtiden hos dynamisk uppdaterade hemsidor ligger hos MQTT och websockets. Med hjälp av Invencon har jag utforskat detta område genom att få en back-end till ett systemet att bygga på. Det har framställts två användargränssnitt för två gruvrobotar som ska kunna ta ordar av ett publicerar-användargränssnitt. Meddelandena skickas som JSON-objekt som är fyllda med information som robotarna ska ta emot. Dessa ordrar kan vara att ändra robotens maximala hastighet. Robotarna uppdaterar sitt gränssnitt i realtid där de samtidigt skickar sin nuvarande hastighet till publiceraren som visar upp dem. Det finns ett fjärrkontroll-gränssnitt där man kan välja en robot som är igång, där gränssnittet presenterar all information om den valda roboten. Användar- gränssnitten skrivs i HTML och CSS där funktionaliteten görs i JavaScript med hjälp av MQTT och websockets. Flera tester har gjorts där man kollar latensen på hur lång tid det tar för ett meddelande att ta sig till en robot och tillbaka till publiceraren för att mäta hur pålitligt systemet är. Efter testerna utfördes, kom jag fram till att fler tester kommer behöva göras för att testa systemet på en högre nivå, då två robotar och en användare inte räcker för ett konkret resultat. Systemet har potential att användas i riktig verksamhet med vidareutveckling av båda tester och bättre back-end. Today’s web browsers are updating their appearance more than ever, and being able to do so efficiently is essential. Compiling a website and uploading it again is inefficient, and the future of dynamically updated websites lies in MQTT and websockets. With the help of Invencon, I have explored this area by establishing a back-end for the system. Two user interfaces have been developed for two mining robots that can receive commands from a publisher-interface. Messages are sent as JSON-objects filled with information that the robots need to receive. These commands can include changing the robot’s maximum speed. The robots update their interfaces in real-time while si- multaneously sending their current speed to the publisher, which displays them. There is a remote control-interface where you can select a running robot, and the interface presents all information about the chosen robot. The user interfaces are written in HTML and CSS, with functionality implemented in JavaScript using MQTT and websockets. Several tests have been conducted to measure the latency of how long it takes for a message to reach a robot and back to the publisher, proving the reliability of the system. After the tests, it was concluded that more testing needs to be done to evaluate the system on a higher level, as two robots and one user are insufficient for a concrete result. The system has the potential to be used in real-world applications with further development of both testing and a better back-end.

Crossing Øresund : A case study of price discrimination on Øresund Bridge

The purpose of this thesis is to investigate the competition structure in the market for crossing Øresund and which price setting techniques are used. The results show that the market for crossing Øresund Bridge is monopolistically competitive market. While Øresund Bridge can in some cases be seen as a monopoly. Furthermore the results show how the firms that are operating in the market offer their consumers various pricing schedules to self-select from. The results based upon the information collected found that Øresund Bridge uses price discriminatory pricing schedules such as two-part tariff, quantity discount and peak-load pricing. According to the theory of price discrimination the firm needs to have market power in order to price discriminate and it is found that Øresund Bridge have a market share of 76%. The negative consequences of price discrimination in the particular market can mostly be seen in the ferry market where the two largest firms have to start collaborating in order to sustain as a part of the market. The positive consequences is found to be that a wider range of consumer groups are able to travel over Øresund due to the extensive range of different prices offered by the market operators

Crossing Øresund : A case study of price discrimination on Øresund Bridge

The purpose of this thesis is to investigate the competition structure in the market for crossing Øresund and which price setting techniques are used. The results show that the market for crossing Øresund Bridge is monopolistically competitive market. While Øresund Bridge can in some cases be seen as a monopoly. Furthermore the results show how the firms that are operating in the market offer their consumers various pricing schedules to self-select from. The results based upon the information collected found that Øresund Bridge uses price discriminatory pricing schedules such as two-part tariff, quantity discount and peak-load pricing. According to the theory of price discrimination the firm needs to have market power in order to price discriminate and it is found that Øresund Bridge have a market share of 76%. The negative consequences of price discrimination in the particular market can mostly be seen in the ferry market where the two largest firms have to start collaborating in order to sustain as a part of the market. The positive consequences is found to be that a wider range of consumer groups are able to travel over Øresund due to the extensive range of different prices offered by the market operators