<div>Observations from experiments and post-earthquake surveys have shown that drift is the key parameter for identifying potential damage of a structure during ground motions (Sozen, 1981). These observations suggest that drift should govern seismic design and evaluation of structures.</div><div><br></div><div>In this study, three methods for estimating drift demands were considered: 1) the method proposed by Sozen (2003) referred to in this study as Velocity of Displacement (VOD), 2) the Coefficient Method and 3) Nonlinear Dynamic Analysis (NDA). The reliability of each method was evaluated by comparing estimates of roof and maximum story drift ratios with measurements from 46 reinforced concrete structures with initial periods shorter than 3 seconds.</div><div><br></div><div>Measurements from long-period structures (with periods longer than 3 seconds) were not available. To produce data to evaluate the reliability of the three mentioned methods for</div><div>long-period structures as well as understand the displacement and base-shear response of such structures, seven scaled Multi-Degree-of-Freedom (MDOF) specimens with an initial period of approximately 1.2 seconds were tested with five scaled base motions of varying intensities. Each motion was scaled in time such that its scaled spectral shape near the initial period of the specimen was similar to the spectral shape of the unscaled motions for periods ranging from approximately 1 to 10 seconds. A total of 118 tests were conducted.</div><div><br></div><div>The effect of loading history on drift demands and drift estimates was also evaluated by quantifying changes in drift demands of structures subjected to repeats of the same ground motion. Data from 1) experimental tests of structures subjected to repeated ground motions, and 2) numerical analyses of Single-Degree-of-Freedom (SDOF) oscillators subjected to multiple sequences of ground motions of varying intensities were used.</div><div><br></div><div><div>Based on comparisons of measured and calculated drifts as well as data from the experimental program, the following observations were made:</div></div><div><br></div><div>1) For structures with periods shorter than 3 seconds, all three methods for estimating drift demands produced estimates of both roof and maximum story drifts of similar</div><div>quality despite large differences in the effort required to use each method.</div><div><br></div><div>2) For structures with periods longer than 3 seconds, NDA produced drift estimates close to the mean of measured values while VOD overestimated measured values, on average, by approximately 30%. The Coefficient Method produced estimates that were, on average, smaller than measurements by approximately 40%.</div><div><br></div><div>3) For structures (not susceptible to decay in lateral strength) subjected to sequences of ground motions of similar intensities, the relative increase in drift demands was,</div><div>on average, no more than 20%. Larger increases in drift demands were observed for structures where the first motion (in a pair of repeated motions) was mild enough</div><div>not to cause cracking and/or yielding, and the second motion was preceded by larger intensity motions that did cause cracking and/or yielding.</div><div><br></div><div>4) For test structures with periods longer than 3 seconds, drifts in the nonlinear range of response were generally smaller than linear estimates, and maximum base-shear</div><div>demands were as much as three times those calculated assuming a linear lateral load distribution.</div>

Bakgrund: I slutet av 2019 upptäcktes coronaviruset vilket föranledde den pandemi vi befinner oss i än idag. Tidigare studier visar på att en kris likt coronapandemin kan innebära förändringar hos revisorers oberoende. Olika företagsskandaler och andra kriser har inneburit att revisionslagar och regler kopplade till revisorers oberoende fått genomgå förändringar. Många tidigare studier belyser en ökad press hos revisorerna i samband med kriser likt coronapandemin. Syfte: Studiens syfte är att utreda hur revisorers oberoende har blivit påverkat av coronapandemin och om pandemin lett till en påverkan på revisorernas förmåga att följa principer och lagar. Metod: Vid datainsamlingen i studien har kvalitativ metod använts. Studien gjordes genom semistrukturerade intervjuer med auktoriserade och erfarna revisorer. Urvalet bestod av revisorer med lång erfarenhet vilket innebar att de arbetat med revision både innan och under coronapandemin. Resultat och slutsats: Studiens resultat visar på att revisorers oberoende har varit opåverkat under coronapandemin men att andra faktorer under revisionen har påverkats. Faktorer så som arbetssättet och att fler uppgifter tillkommit. I empirin framkom det att de intervjuade revisorerna ändå har upplevt en ökad press bland annat i bedömningen om företags fortsatta drift. Många företag har haft det tufft i coronapandemin vilket har lett till att revisorer fått medverka i en del obekväma diskussioner med klienter men enligt revisorerna har det ändå inte påverkat deras oberoendeställning. Det framkom också att revisorerna inte såg en ökad risk för vänskapshot när revision sker på distans. Slutligen har revisorerna fått i uppdrag att granska olika stödåtgärder under pandemin. Dessa granskningsåtgärder kan anses gynna revisionens roll som ett legitimitetsstärkande verktyg för företag. / Background: The COVID-19 virus was first observed in late 2019. This virus has set the stage for the pandemic situation we still are living in today. Earlier studies show that a crisis like the COVID-19 pandemic may result in changes in auditor independence. Different business scandals as well as other crises has resulted in changes in auditing laws and regulations connected to auditor independence. Several studies also express an increasing pressure for auditors during crises such as the COVID-19 pandemic. Purpose: The purpose of the study is to examine how auditor independence has been affected due to COVID-19 and if the pandemic situation has resulted in an effect on the auditors’ ability to follow auditing laws and regulations. Method: In order to collect data a qualitative method has been used. The study used semi-structured interviews with authorized and well-experienced auditors. The sample consisted of experienced auditors who have worked in the field of auditing both before and during the pandemic. Result and conclusion: The result of the study shows that auditor independence has not been affected during the COVID-19 pandemic. The study does however show that other factors of the auditing has been affected. Factors such as changes in working methods and additional work tasks to be completed. In the empirical findings it was shown that the interviewed auditors had been experiencing an increased pressure in connection with their assessment of the companies’ going concern. Many companies have been experiencing a tough economic situation during the coronavirus pandemic, which has led to auditors having uncomfortable discussions with clients. However, according to the auditors interviewed the auditor independence have not been affected. Moreover, the empirical findings show that the auditors did not see an increased risk for familiarity threat when the auditing is held virtually. Lastly, the result of the study show that auditors have taken on the responsibility to revise different support measures during the pandemic. These revisions can be seen as a way of promoting the role of auditing as a tool for companies to achieve legitimacy.

Shutter-less infrared cameras based on microbolometer focal plane arrays (FPAs) are the most widely used cameras in thermography, in particular in the fields of handheld devices and small distributed sensors. For acceptable measurement uncertainty values the disturbing influences of changing thermal ambient conditions have to be treated corresponding to temperature measurements of the thermal conditions inside the camera. We propose a compensation approach based on calibration measurements where changing external conditions are simulated and all correction parameters are determined. This allows to process the raw infrared data and to consider all disturbing influences. The effects on the pixel responsivity and offset voltage are considered separately. The responsivity correction requires two different, alternating radiation sources. This paper presents the details of the compensation procedure and discusses relevant aspects to gain low temperature measurement uncertainty.

<p>Masonry infills historically have increased in-plane stiffness and reduced drift demands of reinforced concrete frames. An inherent risk remains during intense ground motions that unreinforced masonry infills can develop shear cracks, fail out-of-plane, or lead to the formation of captive-column conditions. This study explored the use of full-bay, plywood panel infills in non-ductile reinforced concrete frames as a novel seismic retrofit. Wood infills were constructed from layers of APA 3/4” Rated Sheathing plywood panels. Infills were tested using two single-bay, single-story concrete frames at 1/3 scale, with initial periods between 0.1 and 0.3 seconds once infilled. External post-tensioning was provided to the columns during all series to prevent column shear failure and doubled as dowel connections between the concrete frame and wood panel infill. Test series were performed on a uniaxial earthquake simulator with the frame bay parallel to the direction of ground motion. Wood infills were approximately 0.36∗𝑏, 0.18∗𝑏, and 0.09∗𝑏 thick, where b is the column width. Multi-layer infills were screw-laminated via a 6” square grid. Infills were tested in previously damaged and nominally pristine frames.</p> <p>During similar ground motions, masonry infills reduced the effective period of the pristine bare frame by approximately 50%. In nominally pristine frames, one-panel plywood infills reduced the bare frame period by a maximum of 50%, and two-panel infills by 60%. One and two-panel wood infills reduced drift demands in comparison to the pristine bare frame by a factor of 1√2∗𝑛 in previously damaged frames and by 12∗𝑛 in nominally pristine frame, where n is the number of panels of plywood across the infill thickness. There was no extra reduction in drift demands resulting from increasing the wood infill thickness beyond two panels. One-panel wood infills failed via out-of-plane buckling causing splitting at a drift demand of approximately 1.5%.</p> <p>The results of this study confirm that wood panel infill retrofits are structurally viable alternatives to stiffen non-ductile reinforced concrete frames. Plywood panel infills reduced drift demands more efficiently per unit thickness and unit weight than masonry infills; the resilience and ease of construction of wood infills suggest expanded use should be explored. Experimental study of full-scale wood infills is needed before this retrofit method could become field deployable.</p>

No description available.

Syfte: En fasad måste vara robust för att fylla sin funktion och materialet måste kunna stå emot angrepp utifrån, biologiska, kemiska och fysikaliska faktorer. Trä och tegel är eftertraktade som fasadmaterial för dagens nybyggda bostadshus. Eftersom olika material reagerar olika på angrepp är det viktigt att det finns skillnader i underhållsstrategier beroende på vilket fasadmaterial som används. Underhållsarbetet är en faktor som påverkar beslutet på fasadmaterial. Undersökningen ger ett underlag inför valet mellan materialen genom att utveckla underhållsstrategier för respektive material. Metod: För att uppnå målet med arbetet har tre metoder använts för att samla in empiri Dessa är litteraturstudie, intervjuer och dokumentanalys. I litteraturstudien samlades information från olika källor på internet in. Dessa källor hjälpte till att bygga ett teoretiskt ramverk om fastighetsförvaltning och underhållsstrategier. Dokumenten och intervjuerna gav praktisk kunskap om förhållningssätt till underhåll. Metoderna var lämpliga eftersom de tillsammans gav teoretisk såväl som praktisk kunskap kring material och underhåll. Den insamlade empirin analyserades och jämfördes för att kunna besvara frågeställningarna och uppnå målet. Resultat: Idag finns olika underhållsstrategier på trä- och tegelfasader. Den generella åsikten är att trä kräver fler underhållsåtgärder än tegel. Det har dock visat sig att det även förekommer problem med till exempel frostsprängning i större omfattning än vad som tidigare antagits. Underhållsplaner upprättas ofta efter grundlig undersökning av en byggnads egenskaper och kartläggning av dess underhållsbehov. Dessa planer används inte regelbundet hos förvaltningsföretag men det finns en önskan bland vissa förvaltare att ha en mer strukturell underhållsplanering i framtiden. Kategorisering av skador och tillkommande underhållsåtgärder kan användas vid upprättande av underhållsplaner. Ett sådant system är Monument Damage Diagnosis System, förkortat MDDS. Underhållsplaner kan också utformas som stegvisa processer som kan användas tillsammans med databaser över fasadens egenskaper och nödvändiga underhållsåtgärder. Konsekvenser: Denna rapport kommer att ge aktörer inom byggbranschen kunskap och olika strategier vid fasadunderhåll. Konsekvenserna blir att: Företag inom byggbranschen upprättar underhållsplaner mer i framtiden. Det upprättas strukturerade bedömningar om risker kopplade till material, byggnadsdel och yttre påverkan. För- och nackdelarna med trä- och tegelfasader uppmärksammas i högre grad än idag. Många riskfaktorer för tegel såsom frostsprängning har tidigare inte beaktats tillräckligt. Det rekommenderas att byggföretag tar till sig den forskning som finns av underhåll av trä- respektive tegelfasader. Eftersom trä är billigare än tegel i byggskedet men dyrare vid underhåll behöver dessa företag göra fler undersökningar om båda materials för- och nackdelar ur ekonomisk synpunkt. Byggföretag behöver om förutsättningarna finns även upprätta underhållsplaner eftersom dessa planer leder till att fel upptäcks tidigare och därmed minskar kostnaderna på lång sikt. Begränsningar: Resultatet är enbart tillämpbart på fasader av trä och fasader av tegel.  Vidare kan resultatet bara tillämpas på bostadshus eftersom inga andra byggnadstyper har undersökts. Underhållsstrategin som utvecklats i rapporten kan i grunden användas i alla typer av klimat dock måste alltid lokala klimatförhållanden beaktas när strategin appliceras i praktiken. Att upprätta en underhållsplan kräver även en god ekonomi därför är det inte säkert att rapportens underhållsstrategi alltid kan upprättas i verkligheten om det finns ekonomiska hinder.  Litteraturstudien har studerat underhållsstrategier på global nivå medan dokumentanalysen och intervjuerna har fokuserat på de lokala förhållandena i Sverige. / Purpose: A façade must be robust to be able to fulfil its role and the material must be able to withstand exterior threats. These threats could be biological, chemical, or physical. Wood and brick are popular as façade materials when it comes to the newly constructed residential buildings of today. Since different materials react different on threats it is vital that there are separate maintenance strategies depending on the choice of façade material. The examination gives the choice between the materials a basis by developing maintenance strategies for respective material Method: To achieve the goal of the project, three methods have been used to collect empirical data. These methods are literature study, interviews, and document analysis. In the literature study, information from different sources on the internet were collected. The sources helped building a theoretical about property management and maintenance management. The document and interviews provided practical knowledge about maintenance approaches. The methods were suitable since together they provided both theoretical and practical knowledge about materials and maintenance. The collected data was analysed and compared to answer the questions and achieve the projects goal. Findings: Today there are different maintenance strategies for wood and brick facades. The general opinion is that wooden facades require more maintenance than brick facades. Although brick facades have had more problems with for example frost shattering than what was assumed before. Maintenance plans are often established after thorough investigation of a building’s properties and mapping of its maintenance needs. These plans aren’t used regularly among property managers but there’s a wish among some of them to have more structural maintenance planning in the future. Categorization of damages and additional maintenance activities can be used when establishing maintenance plans. One such system is Monument Damage Diagnosis System, abbreviated MDDS. Maintenance plans could also be formulated as step-by-step processes that could be used together with databases of a façade's properties and necessary maintenance actions. Implications: This study will give actors in the construction industry better knowledge about different strategies for façade maintenance. The consequences will be: That companies in the construction industry establish maintenance plans more in the future. That structural evaluations of risks depending on material, building component and external influence are established That strengths and weaknesses with wooden facades and brick facades are paid attention to more in the future. Many risk factors affecting brick facades has not been sufficiently acknowledged before. It is recommended that construction companies take note of current research on maintenance of wooden and brick facades. Since wood is cheaper to build with but more expensive to maintain than brick companies need to do more studies about these materials strengths and weaknesses. Construction companies also need to establish and follow maintenance plans if the conditions are right since that would lead to damages being discovered earlier and therefore decreases costs in a long term. Limitations: The result is only applicable on wooden and brick facades. Furthermore, the result can only be applied on residential houses since no other type of building has been examined. The maintenance strategy that has been developed in the report is in can be used in all climates, but local climate circumstances must always be considered then the strategy is applied in practice. Establishing a maintenance plan requires a good economy therefore it is not certain that the report’s maintenance strategy will always be possible to establish in reality if there are economical limits. The literature study has examined maintenance strategies on a global scale while the document analysis and the interviews has focused on the local circumstances in Sweden.

Dans cette thèse, nous considérons le problème de la classification supervisée sur un flux de données sujets à des changements de concepts. Afin de pouvoir apprendre dans cet environnement, nous pensons qu’un algorithme d’apprentissage doit combiner plusieurs caractéristiques. Il doit apprendre en ligne, ne pas faire d’hypothèses sur le concept ou sur la nature des changements de concepts et doit être autorisé à s’abstenir de prédire lorsque c’est nécessaire. Les algorithmes en ligne sont un choix évident pour traiter les flux de données. De par leur structure, ils sont capables de continuellement affiner le modèle appris à l’aide des dernières observations reçues. La structure instance based a des propriétés qui la rende particulièrement adaptée pour traiter le problème des flux de données sujet à des changements de concept. En effet, ces algorithmes font très peu d’hypothèses sur la nature du concept qu’ils essaient d’apprendre ce qui leur donne une flexibilité qui les rend capable d’apprendre un vaste éventail de concepts. Une autre force est que stocker certaines des observations passées dans la mémoire peux amener de précieuses meta-informations qui pourront être utilisées par la suite par l’algorithme. Enfin, nous mettons en valeur l’importance de permettre à un algorithme d’apprentissage de s’abstenir de prédire lorsque c’est nécessaire. En effet, les changements de concepts peuvent être la source de beaucoup d’incertitudes et, parfois, l’algorithme peux ne pas avoir suffisamment d’informations pour donner une prédiction fiable. / In this thesis, we investigate the problem of supervised classification on a data stream subject to concept drifts. In order to learn in this environment, we claim that a successful learning algorithm must combine several characteristics. It must be able to learn and adapt continuously, it shouldn’t make any assumption on the nature of the concept or the expected type of drifts and it should be allowed to abstain from prediction when necessary. On-line learning algorithms are the obvious choice to handle data streams. Indeed, their update mechanism allows them to continuously update their learned model by always making use of the latest data. The instance based (IB) structure also has some properties which make it extremely well suited to handle the issue of data streams with drifting concepts. Indeed, IB algorithms make very little assumptions about the nature of the concept they are trying to learn. This grants them a great flexibility which make them likely to be able to learn from a wide range of concepts. Another strength is that storing some of the past observations into memory can bring valuable meta-informations which can be used by an algorithm. Furthermore, the IB structure allows the adaptation process to rely on hard evidences of obsolescence and, by doing so, adaptation to concept changes can happen without the need to explicitly detect the drifts. Finally, in this thesis we stress the importance of allowing the learning algorithm to abstain from prediction in this framework. This is because the drifts can generate a lot of uncertainties and at times, an algorithm might lack the necessary information to accurately predict.

This dissertation presents a novel approach to develop a system for real-time tracking of the position and orientation of the human hand in three-dimensional space, using MEMS inertial measurement units (IMUs) and infrared cameras. This research focuses on the study and implementation of an algorithm to correct the gyroscope drift, which is a major problem in orientation tracking using commercial-grade IMUs. An algorithm to improve the orientation estimation is proposed. It consists of: 1.) Prediction of the bias offset error while the sensor is static, 2.) Estimation of a quaternion orientation from the unbiased angular velocity, 3.) Correction of the orientation quaternion utilizing the gravity vector and the magnetic North vector, and 4.) Adaptive quaternion interpolation, which determines the final quaternion estimate based upon the current conditions of the sensor. The results verified that the implementation of the orientation correction algorithm using the gravity vector and the magnetic North vector is able to reduce the amount of drift in orientation tracking and is compatible with position tracking using infrared cameras for real-time human hand motion tracking. Thirty human subjects participated in an experiment to validate the performance of the hand motion tracking system. The statistical analysis shows that the error of position tracking is, on average, 1.7 cm in the x-axis, 1.0 cm in the y-axis, and 3.5 cm in the z-axis. The Kruskal-Wallis tests show that the orientation correction algorithm using gravity vector and magnetic North vector can significantly reduce the errors in orientation tracking in comparison to fixed offset compensation. Statistical analyses show that the orientation correction algorithm using gravity vector and magnetic North vector and the on-board Kalman-based orientation filtering produced orientation errors that were not significantly different in the Euler angles, Phi, Theta and Psi, with the p-values of 0.632, 0.262 and 0.728, respectively. The proposed orientation correction algorithm represents a contribution to the emerging approaches to obtain reliable orientation estimates from MEMS IMUs. The development of a hand motion tracking system using IMUs and infrared cameras in this dissertation enables future improvements in natural human-computer interactions within a 3D virtual environment.

No description available.

Las edificaciones construidas sobre suelo costero, ubicados sobre el cinturón del fuego presentan un alto riesgo sísmico, ya que sobre estas existen condiciones de suelo desfavorables y en otros casos subducción de placas. Esto ha conllevado a que los países ubicados en estas zonas desarrollen normativas sísmicas que permitan el diseño adecuado de obras de ingeniería; sin embargo, diversos reglamentos presentan distintas consideraciones para el diseño como la utilización de los parámetros que permiten estandarizar el diseño que muchas veces no presentan las mismas respuestas sísmicas del comportamiento dinámico real del suelo. Por ello, la presente investigación propone evaluar la respuesta sísmica de dos edificaciones, una esencial y otra común, con un análisis utilizando espectros de sitio, un análisis dinámico modal espectral y adicionalmente un análisis tiempo-historia teniendo consideraciones de tipos de suelo y utilización de distintos parámetros sísmicos de normas sudamericanas. El principal resultado es que la respuesta sísmica por análisis con espectros de sitio (ES) es mayor en comparación con el análisis dinámico modal espectral según la magnitud de los sismos y la tipología de suelos. / The buildings built on coastal soil, located on the fire belt present a high seismic risk, since there are unfavorable soil conditions and in other cases plate subduction. This has led to countries located in these areas developing seismic regulations that allow the proper design of engineering works; however, various regulations present different considerations for the design, such as the use of parameters that allow standardizing the design that often does not present the same seismic responses of the real dynamic behavior of the soil. Therefore, the present research proposes to evaluate the seismic response of two buildings, one essential and the other common, with an analysis using site spectra, a dynamic spectral modal analysis and additionally a time-history analysis taking into account soil types and use of different seismic parameters of South American standards. The main result is that the seismic response by analysis with site spectra (ES) is greater compared to the dynamic spectral modal analysis according to the magnitude of the earthquakes and the type of soil / Tesis