On the use of weather radar for mesoscale applications in northern conditions

Mesoscale weather phenomena, such as the sea breeze circulation or lake effect snow bands, are typically too large to be observed at one point, yet too small to be caught in a traditional network of weather stations. Hence, the weather radar is one of the best tools for observing, analyzing and understanding their behavior and development. A weather radar network is a complex system, which has many structural and technical features to be tuned, from the location of each radar to the number of pulses averaged in the signal processing. These design parameters have no universal optimal values, but their selection depends on the nature of the weather phenomena to be monitored as well as on the applications for which the data will be used. The priorities and critical values are different for forest fire forecasting, aviation weather service or the planning of snow ploughing, to name a few radar-based applications. The main objective of the work performed within this thesis has been to combine knowledge of technical properties of the radar systems and our understanding of weather conditions in order to produce better applications able to efficiently support decision making in service duties for modern society related to weather and safety in northern conditions. When a new application is developed, it must be tested against ground truth . Two new verification approaches for radar-based hail estimates are introduced in this thesis. For mesoscale applications, finding the representative reference can be challenging since these phenomena are by definition difficult to catch with surface observations. Hence, almost any valuable information, which can be distilled from unconventional data sources such as newspapers and holiday shots is welcome. However, as important as getting data is to obtain estimates of data quality, and to judge to what extent the two disparate information sources can be compared. The presented new applications do not rely on radar data alone, but ingest information from auxiliary sources such as temperature fields. The author concludes that in the future the radar will continue to be a key source of data and information especially when used together in an effective way with other meteorological data.

Towards Understanding Powder Behavior Via Simulation

The aim of this study was to investigate powder and tablet behavior at the level of mechanical interactions between single particles. Various aspects of powder packing, mixing, compression, and bond formation were examined with the aid of computer simulations. The packing and mixing simulations were based on spring forces interacting between particles. Packing and breakage simulations included systems in which permanent bonds were formed and broken between particles, based on their interaction strengths. During the process, a new simulation environment based on Newtonian mechanics and elementary interactions between the particles was created, and a new method for evaluating mixing was developed. Powder behavior is a complicated process, and many of its aspects are still unclear. Powders as a whole exhibit some aspects of solids and others of liquids. Therefore, their physics is far from clear. However, using relatively simple models based on particle-particle interaction, many powder properties could be replicated during this work. Simulated packing densities were similar to values reported in the literature. The method developed for describing powder mixing correlated well with previous methods. The new method can be applied to determine mixing in completely homogeneous materials, without dividing them into different components. As such, it can describe the efficiency of the mixing method, regardless of the powder's initial setup. The mixing efficiency at different vibrations was examined, and we found that certain combinations of amplitude, direction, and frequencies resulted in better mixing while using less energy. Simulations using exponential force potentials between particles were able to explain the elementary compression behavior of tablets, and create force distributions that were similar to the pressure distributions reported in the literature. Tablet-breaking simulations resulted in breaking strengths that were similar to measured tablet breaking strengths. In general, many aspects of powder behavior can be explained with mechanical interactions at the particle level, and single particle properties can be reliably linked to powder behavior with accurate simulations.

Factors Affecting Knowledge Sharing in Strategic Alliances: The Role of Knowledge Sharing as Strategic Control Behavior among Multinational Enterprises

International strategic alliances (ISAs) have become increasingly important for the stability, growth, and long-term viability of modern business organizations. Alliance partnerships as inter-firm cooperative ventures represent an influential mechanism for asserting corporate strategic control among autonomous multinational enterprises. These different cooperative arrangements are made of equity investments or contractually-based partnerships. Different alliance forms represent different approaches that partner firms adopt to control their mutual dependence on the alliance and on other partners. Earlier research shows that the partner characteristics could provide an explanation for alliance strategic behavior and see alliances as alternative forms to markets or hierarchies for addressing specific strategic needs linked to partners’ characteristics and their subsequent strategic motives. These characteristics of the partners’ and subsequent strategic motives are analyzed as knowledge sharing factors and how these influence inter-firm control in alliances within the context of the focal-firm STMicroelectronics and its alliance partners Nokia, Ericsson and IBM. This study underline that as contracts are incomplete, they are therefore required to maintain mutual dependence based control mechanisms in addition to a contract. For example, mutual dependence based control mechanisms could be joint financial investments and the building of an ownership structure between the parties (e.g., JVs). However, the present study clarifies that subsequent inter-firm control is also exercised through inter-firm knowledge sharing. The present study contributes by presenting a dynamic interplay between competitive and cooperative rent seeking behavior. Such coopetition behavior describes the firm's strategic orientation to achieve a dynamic balance between competitive and cooperative strategies. This balance is seen in knowledge sharing based cooperation and competition behavior. Thus this study clarifies coopetition strategies by introducing the role of inter-firm cooperation and the competitive nature of knowledge sharing. Simultaneous cooperative and competitive behavior is also seen as synergetic rent-seeking behavior. Therefore, this study extends the perspective of previous studies on competitive and cooperative seeking behavior.