Spacecrafts are generally equipped with high precision optical and other sensor payloads. The structures of most of the spacecrafts are light-weight, flexible and have low damping. Vibrations are often induced in the spacecraft body due to the presence of many disturbance sources such as momentum/reaction wheels, control thrusters used for attitude control and cryocoolers etc. Low damping leads to long decay time for vibrations hence during this period the spacecraft sensors cannot be used effectively. One possible solution is to isolate the precision sensor from the rest of the satellite and this strategy has been used for spaceborne telescopes and interferometers that have extremely precise positional and vibratory tolerances imposed on them in order to achieve scientific goals. Another strategy is to isolate the vibration source itself from the spacecraft body. This thesis deals with modelling, analysis and experimentation of a novel low frequency flexible space platform designed to serve as a mount for the disturbance source in order to insulate the source generated vibrations reaching critical areas of the structure. The novel space platform consisting of folded continuous beams, is light-weight and is capable of isolating vibration generated by sources such as reaction/momentum wheels. Finite element analysis of the platform is carried out for static and dynamic load cases. Simulation studies are carried out on flexible beam platform in order to firm up the design for passive vibration isolation. Modal analyses is done to simulate the response of each mode. Active control has been studied by embedding the platform’s beam elements with piezo actuators and sensors. The simulation results show that the space platform can effectively attenuate vibration and further improvement in vibration attenuation is possible with active control. Based on the analysis, a prototype low frequency platform has been designed and fabricated. An experimental validation has been done to test the usefulness of the low frequency platform to act as a mount for reaction wheels and to mitigate the vibration disturbances/effects transmitted from the reaction wheel assembly to structure. Measurements and tests have been conducted at varying wheel speeds to quantify and characterize the amount of isolation to the reaction wheel generated vibrations. The time and frequency domain analysis of test data clearly show that level of isolation is significant and an average of 13 dB of isolation is seen. The level of isolation is different for different isolators and it depends upon the isolator design and wheel speed. Forces and moments measured at the base for wheel with isolator and wheel without isolator clearly demonstrate and confirm a reduction in the disturbance levels of atleast one order. These isolators are further tested successfully for launch dynamic loads in order to confirm the design adequacy to sustain such loads. Results indicate that the flexible mounts of the type discussed in this thesis can be used for effective passive vibration isolation in spacecrafts with reaction/momentum wheels.

My dissertation, titled “From the machine mind to the human mind: using machine learning to understand (ir)rationality, bias and polarization in human beings,” investigates ways in which human minds operate and seeks to uncover the causes of biasedness, limited rationality, and polarization of human minds, to eventually devise tools to compensate for such human limitations. Chapter 2 of the thesis focuses on the evaluation of information and decision making under enormous information asymmetry, in the setting of patients evaluating doctors’ medical advice. Patients were found to be poor evaluators who were unable to distinguish good from bad due to their lack of medical expertise, and unable to overcome their own irrationality and bias. I emphasize the ramification of such limited rationality, which might lead to the adoption of suboptimal or bad medical opinions, and propose ways to improve this situation by redesigning some features of the platform, and/or implementing new policies to help good doctors on the platform. Chapter 3 focuses on developing a new metric that reliably measures the ideology of the US elites. This metric was developed based on congressional reports which made it unique and relatively independent from established metrics based on roll call votes, such as DW-NOMINATE. First, I leveraged a neural network-based approach to decompose the speech documents into frames and topics components, with all ideological information funneled into the frames component. Eventually, two different ideology metrics were obtained and validated: an embedding vector and an ideological slant score. Later I showed that our new metrics can predict party switchers and trespassers with high recall. In chapter 4, I applied the newly obtained metric (mainly slant scores) to investigate various aspects of the congress, such as the heterogeneity of ideology among the members, the temporal evolution of partisan division, the bill passing, and the re-election strategy of the senators.

This dissertation studies three economic problems plagued by multiple equilibria. Indeterminacy of equilibrium outcome often poses a challenge in deriving robust predictions and policy guidance. The dissertation shows how the utilization of potential game theory can better deal with this challenge. Chapter 1 studies a general contracting problem between one principal and multiple agents. The interdependence of agents’ actions and payoffs creates a coordination problem among them, leading to multiple equilibria. In general, the principal’s optimal contracting scheme varies with how one selects among equilibria. Nevertheless, for a large class of contracting models where agents’ payoffs constitute a weighted potential game, I show that one contracting scheme is optimal for a large class of equilibrium selection criteria. This scheme ranks agents in increasing weight in the weighted potential game and induces them to accept their offers in a dominance-solvable way, starting from the first agent. I also apply the general results to networks and pure/impure public goods/bads. Chapter 2 studies two-sided markets, where two groups of agents interact via platforms. These markets exhibit network effects, i.e., the value of joining a platform increases with the number of users, which in turn lead to multiple equilibria. I show that many two-sided market models are weighted potential games, enabling the selection among equilibria by potential maximization—a refinement of Nash equilibrium justified by many theoretical and experimental studies. Under potential maximization, platforms often charge the side deriving more network benefits and subsidize the other side. Therefore, profit-maximizing platforms are often designed to favor the money side much more than the subsidy side. Chapter 3 studies markets with strong network effects. In these markets, firms compete for the adoption of all consumers rather than the marginal consumer. Therefore, the Spence distortion—a quality distortion driven by competition for the marginal consumer—should be absent, contradicting the findings in the network economics literature. This inconsistency stems from the choice of equilibrium selection criterion. I show that all popular selection criteria in that literature lead to Spence distortions, whereas potential maximization does not. Therefore, network market regulations based on Spence distortion arguments may be misguided.

This thesis provides an analysis of digital platforms and its impact on labour law and related work patterns in general. The main focus is upon description of caused problems and their possible solutions whereas the question of worker's status in the platform economy and its arrangements is predominantly discussed. The introduction leads the reader to general description of digital platforms and its three main subsets (crowdsourcing, on deman work and passenger transport services). For a better undestanding the thesis further gives an idea of working conditions by analysing each working stage affected by platforms. After these initial introductory findings the thesis focuses on potential problems. The possible problems are first being described in general and then discussed from the practical point of view as they were already seen by various courts in the past. The sole analysis of courts decision is rather extensive since the three chosen decisions not only give us answers to some problematic questions but they also provide highly beneficial info about platforms in general and their business models as well. Finally, after the thesis is done with court decisions it continues to analyze applicable legal frameworks. First are being analyzed the European requirements and frameworks provided by EU...

Social platforms have become a large part of today’s society and there is large scientific interests in what creates a successful social platform. There is plenty of research available on how to acquire users to a social platform, but there is significantly less available on how to retain users on a social platforms. It is easy to forget that acquiring users is only half the battle, users that do not return is of little use. Thus, there is demand for research on how to retain users on social platforms, which is something that are of interest of both developing and established social platforms. This study aim to answer two research questions: “What drives continued use of social platforms?” and “How can CRM and Gamification tools be used to retain users on social platforms?” The factors that are investigated in this paper were derived from current literature. Based on the literature review, a conceptual framework was built from existing theory. The conceptual framework was used as the starting point for our data collection. Data was collected in the form of ten interviews of students currently enrolled at instutiotions of higher education. Later, the primary data were contrasted with the secondary data in order to draw conclusions. The results suggests that previous research have neglected some externalities such as trends and context, and the fact that the drivers for use differ depending on the social platform in question. Finally, a revised conceptual model is presented, it is a modified version of the conceptual model, where the new findings are added in order to create an illustration of how our research added to the existing research on the subject. The findings can be used by management on social platforms to develop user retention strategies. Further, the findings from this study can be used as a foundation for future research on the topic.

Relevant market on multisided online platforms in the view of the European Commission and doctrine Abstract The master thesis deals with the issue of defining the relevant market in relation to multilateral platforms. In its first part, it analyzes in detail the leading theories regarding a definition of a multisided platform is its typology. The conclusions of these analyzes then form the basis of the second part, which is the core of the work. There are described leading methods of defining the relevant market, problems with their application to multisided platforms and doctrinal proposals on how to modify these methods. This core part first deals with the dilemma of defining one market encompassing both sides of a platform or separate markets for each side of the platform and then it focuses on the issue of implementation of the SSNIP test. The individual decisions of the Commission are confronted with the comprehensive conclusions of the doctrine within the individual analyzes, and the compliance of the Commission's approach in the given decision with the doctrine is assessed here. Keywords: multisided platforms, relevant market, SSNIP test

Digitala plattformar är idag vanligt förekommande ochanvänds av flera organisationer. Tidigare forskning harframförallt fokuserat på de tekniska aspekterna avdigitala plattformar och främst på de större mervälkända digitala plattformarna som Facebook ochGoogle. Därför har denna studie som syfte att beskrivade möjligheter och utmaningar sex svenska företagverksamma inom olika affärsområden upplever meddigitala plattformar i relation till samarbete. Studiengenomfördes med sex små och medelstora företagverksamma inom olika affärsområden. Studien är enkvalitativa intervjustudie med en abduktiv metod.Intervjuerna genomfördes med en respondent från varoch en av företagen. Resultatet av studien visar att detfinns många möjligheter och utmaningar med digitalaplattformar i relation till samarbete. De möjligheter somidentifierades var mer effektiva processer, integrationmellan olika system, förändrade roller, uppkomsten avdigitala ekosystem, kombination av resurser ochmöjligheter till kunskapsdelning. Möjligheternaskapade också olika utmaningar som identifierades somsambandet mellan människor och den digitalaplattformen, kontroll av innehållet, värdeskapandet föralla parter, rutiner och processer och beroendet mellanaktörer i nätverken. Med resultatet av denna studie villjag bidra med ny kunskap inom fältet digitalaplattformar, men även visa företag vilka möjligheternadigitala plattformar skapar i samarbete och vilkautmaningar de behöver tänka på / Digital platforms are common today and manyorganizations use digital platforms. Recent research inthe field have focused on the technical aspects of thedigital platforms and often on the more recognizeddigital platforms such as Facebook and Google.Therefore, this study has purpose to describe theopportunities and challenges six Swedish companiesoperating in different business areas experience withdigital platforms in relation to cooperation. The studywas made with six Swedish small and medium sizedbusiness that operated in different business areas. I haveused qualitative interview studies with an abductivemethodology. The interviews were conducted with onerespondent from each of the businesses. The resultshows that there are many opportunities and challengeswith digital platforms in the aspect of cooperation. Theopportunities that was identified was more effectiveprocesses, integration between different systems,changing roles, the creation of digital ecosystems,combination of recourses and possibilities to shareknowledge. The opportunities also created differentchallenges which was identified as the connectionbetween people and the digital platform, the control ofthe content, value creation for all parties, routines andprocesses and dependency between actors in thenetwork. With the result from this study I want tocontribute with new knowledge to the field digitalplatforms but also to show the businesses theopportunities digital platforms create in cooperation andwhat challenges they need to think of.

Existing studies on the formulation of regulations for online ride-hailing platforms merely see the process as a struggle between interest groups. They do not address how policymakers perceive this struggle and act on their own initiative to govern these platforms. This study supplements existing studies by exploring how the metropolitan governments of two Chinese cities, Beijing and Shanghai, perceived conflicts between contending forms of chauffeur businesses and brought in regulations for new platform ventures. This thesis employs a policy change approach in the Chinese authoritarian context and reaches three conclusions. Firstly, it explains that the "special interests" of taxi entities institutionalized by the old regulatory regimes for taxi businesses incentivized the two metropolitan governments to protect taxi entities. Thus, even if Beijing and Shanghai had different first responses towards platforms with one initially emphasizing "cracking-down" and the other working on a "loose" regulatory approach, they adopted similar platform-capping policies. Secondly, this thesis finds that the two metropolitan governments cautiously disobeyed the central government's "loose" directives for platforms by combining their capping policies with selectively implementing a central directive of differentiating the markets of ride-hailing platforms and taxi operators. Thirdly, this thesis addresses obstructions to the establishment of "new regulation" that respects the business logic of platforms, which is proposed by the platform coalition. It argues that the interaction between the vested "special interests" and the fragmentation of authority makes local governments resistant to this "new regulation." / Graduate

The main objectives of this study were to develop the indicatri es of reflected solar radiation from different natural surfaces and to show comparisons between values sensed in space of emergent radiation to ground values obtained from accounting for anisotropic reflection and estimating the effect of the intervening atmosphere. Thus, this study demonstrated that a prior knowledge of the angular distribution of reflected radiation allows determining the true hemispherical reflected radiation from a narrow field of view instrument such as found on a flying platform. Measurements for determining the indicatrices were made from a tower-mounted Nimbus MRIR and, in one case, with a hand-held TIROS five-channel radiometer. Anisotropy of reflected radiation was found for all surfaces examined and increased with decreasing solar angle. Different surfaces showed different degrees and patterns of fonvard and backscatter. A clearly defined anti-solar point was found for plowed field, various agricultural crops and vegetated desert surfaces, while snow, the Alkali Flats, and Bonneville Salt Flats showed a broad pattern of backscatter. As a consequence of surfaces exhibiting well-defined antisolar points the anisotropic correction factors relating normal reflectances to 2π reflected values were less than 100 percent for solar angles greater than approximately 60°. All surfaces examined showed anisotropic correction factors increasing with decreasing solar angles. The albedo over the White Sands dune field decreased with decreasing solar angles due to large shadow patterns which are produced at low solar angles. The sand dunes values were derived from aircraft measurements. Comparisons were made between estimated emergent radiation from the top of the earth 's atmosphere accounting for anisotropy of the ground reflection pattern and estimates of atmospheric attenuation to values of reflected radiation obtained from the MSS subsystem of the ERTS program for the lava beds region and White Sands area in New Mexico. Also comparisons were shown between the estimated emergent radiation from the earth's surface for the same features and spectral bands to the values sensed in space. Under high albedo conditions as found in the White Sands area there was a decrease in emergent radiation to space while with low surface albedo, such as the lava beds region, the extra-terrestrial radiation increased from the ground values.

abstract: Two-sided online platforms are typically plagued by hidden information (adverse selection) and hidden actions (moral hazard), limiting market efficiency. Under the context of the increasingly popular online labor contracting platforms, this dissertation investigates whether and how IT-enabled monitoring systems can mitigate moral hazard and reshape the labor demand and supply by providing detailed information about workers’ effort. In the first chapter, I propose and demonstrate that monitoring records can substitute for reputation signals such that they attract more qualified inexperienced workers to enter the marketplace. Specifically, only the effort-related reputation information is substituted by monitoring but the capability-related reputation information. In line with this, monitoring can lower the entry barrier for inexperienced workers on platforms. In the second chapter, I investigate if there is home bias for local workers when employers make the hiring decisions. I further show the existence of home bias from employers and it is primarily driven by statistical inference instead of personal “taste”. In the last chapter, I examine if females tend to have a stronger avoidance of monitoring than males. With the combination of the observational data and experimental data, I find that there is a gender difference in avoidance of monitoring and the introduction of the monitoring system increases the gender wage gap due to genders differences in such willingness-to-pay for the avoidance of monitoring. These three studies jointly contribute to the literature on the online platforms, gig economy and agency theory by elucidating the critical role of IT-enabled monitoring. / Dissertation/Thesis / Doctoral Dissertation Business Administration 2019