213 research outputs found

    Using resistivity measurements for dam safety evaluation at Enemossen tailings dam in southern Sweden

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    Internal erosion is a major reason for embankment dam failures. Resistivity measurements is an essentially non-destructive technique, which may have the possibility of detecting internal erosion processes and anomalous seepage at an early stage before the safety of the dam is at stake. This paper presents results from part of a dam safety investigation conducted at the Enemossen tailings dam in southern Sweden. Longitudinal resistivity sections, 2D measurements along the dam crest, provided an overview of the whole dam and served to detect anomalous zones. In selected areas, additional cross-sectional 2D surveys gave detailed information about the geo-electrical situations in the embankments. This information is valuable for similar investigations as information about resistivity in embankment construction material is scarce. Known problem areas were associated with low resistivities, even though the resistivity measurements alone did not provide enough information to confidently come to a decision about the status of the dams

    Does the fashion of a management strategy affect the stock price? An event study of the fashion of downsizing

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    The purpose with this thesis is to examine whether the popularity of downsizing as a management strategy has an effect on the stock market's reactions when a company announces downsizing. This thesis has employed a quantitative method. An event study has been used and we have calculated the normal and abnormal return using the market model. Data has been collected from Datastream in forms of stock prices and Affärsdata has been used to find the announcements about downsizing. The event window has been (-2, +2) days considering previous research. According to the statistical tests there are no differences between the two CAARs, which means that the stock market´s reaction to an announcement of downsizing does not differ when downsizing was in fashion and when it was not

    Investigation of shallow leakage zones in a small embankment dam using repeated resistivity measurements in Internal erosion in embankment dams and their foundations

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    Resistivity measurements were carried out in order to identify preferential seepage paths in a small dam in central Sweden. Increased seepage flow had been observed at high reservoir levels. Repeated resistivity measurements were performed along the dam crest during 24 hours controlled rising of the reservoir. Each measurement data set was compared to the original reference data set using time-lapse inversion. Zones with gradually decreasing resistivity were identified inside the dam at the depth corresponding to the changed reservoir level. The zones were interpreted as preferential seepage paths. During a possible future repair of the dam this interpretation may be evaluated

    Detection of Internal Erosion and Seepage Evaluation Using Resistivity Monitoring

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    The resistivity method is well suited for dam monitoring as it is non-destructive and easily adapted for long-term monitoring. Measurements detect changes of material properties as well as anomalous variations, which may relate to internal erosion and seepage. However, applying the resistivity method on embankment dams can be challenging. This paper contends with practical use of the resistivity method on embankment dams, and presents two examples from Sweden

    Ledarskapspreferenser i olika organisationstyper

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    The purpose of this study was to examine if the employees view on leadership differs in different kinds of organizations. The purpose was also to examine if the employees prefers transformational leadership rather than a transactional leadership. The survey addressed approximately 400 people, half of them work in a municipality and half of them work in a digital entertainment company. The results show that transformational leadership is preferred by the majority of the employees but no significant differences could be found between the different organizations

    Assessment Based Information Needs in Manual Assembly

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    To handle the complex and flexible manufacturing of today it is vital to have well functional information systems for the operators so that they know when, what and where to assemble. The current designs of assembly work instructions differ much between companies, but also between plants within the same company. The digitalization trends and initiatives such as Industry 4.0 show the manufacturing industry the advantages to incorporate new methods and tools into their businesses. Even though manufacturing IT systems are designed to be adaptive to product and volume changes, they are still widely characterized by their rigid structures. Making large changes to manufacturing IT systems with comprehensive structures is complex and requires large amounts of resources. Therefore, it is important for the manufacturing companies to make the correct investments. In previous studies, two current state analyses have been conducted with the aim to map manufacturing engineering processes and IT systems producing assembly work instructions in a mass customization context. This paper presents results from the third part of a longitudinal study which focuses on identifying operators’ information needs in manual assembly of heavy vehicles. This third study aims to identify the information gap between the current state and the wanted state by assessing information needs at 13 assembly stations in three plants belonging to a global production network. The purpose is to identify design requirements for future assembly information systems enabling the practical use of the digitalization

    Temperature Stabilization of the Phase-Reference Line at the European Spallation Source

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    We consider temperature stabilization of the phase-reference line at the European Spallation Source, a facility for neutron spallation currently under construction. Based on extensive modeling of the heat dynamics, a prototype model-based control system with associated hardware architecture is developed and experimentally evaluated on a small-scale setup. The results indicate that temperature stability within ±0.1°C is possible to achieve, also with significant disturbances in the ambient temperature expected during operation

    Applying the Quantum Approximate Optimization Algorithm to the Tail Assignment Problem

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    Airlines today are faced with a number of large scale scheduling problems. One such problem is the tail assignment problem, which is the task of assigning individual aircraft to a given set of flights, minimizing the overall cost. Each aircraft is identified by the registration number on its tail fin. In this article, we simulate the Quantum Approximate Optimization Algorithm (QAOA) applied to instances of this problem derived from real world data. The QAOA is a variational hybrid quantum-classical algorithm recently introduced and likely to run on near-term quantum devices. The instances are reduced to fit on quantum devices with 8, 15 and 25 qubits. The reduction procedure leaves only one feasible solution per instance, which allows us to map the tail assignment problem onto the Exact Cover problem. We find that repeated runs of the QAOA identify the feasible solution with close to unit probability for all instances. Furthermore, we observe patterns in the variational parameters such that an interpolation strategy can be employed which significantly simplifies the classical optimization part of the QAOA. Finally, we empirically find a relation between the connectivity of the problem graph and the single-shot success probability of the algorithm.Comment: 11 pages, 10 figure
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