Practical inventory settings often include multiple generations of the same product on hand. New products often arrive before old stock is exhausted, but most inventory models do not account for this. Such a setting gives rise to the possibility of inter-generational substitution between products. We study a retailer that stocks two product generations and we show that from a cost perspective the retailer is better off stocking only one generation. We proceed with a profit scheme and develop a price-setting profit maximization model, proving that in one and two generation profit models there exists a unique solution. We use the profit model to show that there are cases where it is more profitable to stock two generations. We discuss utility and preference extensions to the profit model and present the general n-product case.

Surface reconstruction of anatomical structures is an integral part of medical modeling. Contour information is extracted from serial cross-sections of tissue data and is stored as "slice" files. Although there are several reasonably efficient triangulation algorithms that reconstruct surfaces from slice data, the models generated from them have a jagged or faceted appearance due to the large inter-slice distance created by the sectioning process. Moreover, inconsistencies in user input aggravate the problem. So, we created a method that reduces inter-slice distance, as well as ignores the inconsistencies in the user input. Our method called the piecewise weighted implicit functions, is based on the approach of weighting smaller implicit functions. It takes only a few slices at a time to construct the implicit function. This method is based on a technique called variational interpolation. <p> Other approaches based on variational interpolation have the disadvantage of becoming unstable when the model is quite large with more than a few thousand constraint points. Furthermore, tracing the intermediate contours becomes expensive for large models. Even though some fast fitting methods handle such instability problems, there is no apparent improvement in contour tracing time, because, the value of each data point on the contour boundary is evaluated using a single large implicit function that essentially uses all constraint points. Our method handles both these problems using a sliding window approach. As our method uses only a local domain to construct each implicit function, it achieves a considerable run-time saving over the other methods. The resulting software produces interpolated models from large data sets in a few minutes on an ordinary desktop computer.

Innovative companies in technologically advanced environments have to deal with the consequences of choosing between a resource based strategy and possibly missing out on the benefits of cooperative knowledge, or collaborating with their network of suppliers, customers and even competitors and risk diluting their competitive advantage. This thesis is concerned with the cooperative aspect within intricate networks of technologically innovative firms. To gain a better understanding of this phenomena, the most innovative sector in Sweden has been chosen for a case study. The purpose of this thesis is to explore the dynamics of innovation within the telecom sector in Sweden, and determine the level of cooperation within the telecom sector, in terms of the flows of information and embeddedness. The method chosen to fulfil this purpose was via a qualitative approach, and in the form of a case study. Relevant data was collected through five interviews with key personnel within the two companies of interest (Ericsson &amp; TeliaSonera), and triangulated with secondary quantitative and qualitative data. Results indicate that the Swedish telecom sector benefits from a fertile environment that fosters innovative activity, and to that reason it has claimed leadership in the worldwide telecommunications industry. Additionally, this same environment promotes collaboration between the different actors in the sector. A closer examination of the cooperation between TeliaSonera and Ericsson in the 4G network roll-out, indicates that the cooperation, albeit being successful, could be ameliorated further through an increased embeddedness of the partnership.

When consumers are able to buy electricity on an hourly instead of monthly basis, the demand side flexibility is likely to increase. One way to lower the cost of electricity is to move consumption from peak price hours to low price hours, a sort of inter-temporal substitution were the net energy use is unaffected. By simulating one example of inter-temporal substitution in the Swedish spot market during 2008-2010, we show that the general welfare effects are small in terms of a more efficient energy production, but that the transfer of resources from producers to consumers is large. Whether the welfare effect is positive or negative is highly dependent on future electricity prices, the introduction of renewable energy resources, and the price of the new technology needed for the demand side regulation. If 2010 is used as a reference case, the results from our specific case concludes that a natural investment equilibrium is reached when approximately 150 000 households invest in the proposed demand side regulation technology. Using the same reference year, we see that if 70 000 households participates the Net Present Welfare benefit is around 10% of the necessary investment cost; to be compared with the transfer of benefits from producers to consumers which estimates roughly 2100% of the necessary investment cost. We argue that this imbalance in potential welfare benefits between producers and consumers might slow down the process of increasing the general welfare.

This essay explores the economical and social paradigms surrounding one of the most influential Nordic border dynastic noble families in the second half of the fifteenth century - the Axelsson Totts. How mercantile possibilities and opportunities offered to them, reflected on their political actions and social bands. The Axelsson brothers of the Tott Dynasty would become of one of the most powerful noble families within the Nordic Union between 1444 och 1487. Axel Pedersen (Tott) would through well chosen marriage alliances into the noble families of both Denmark and Sweden, and with political prowess lay the foundation for one of the most dynamic family empires of the fifteenth century. In the year 1442, the Axelsson brothers swore loyalty to each other; to protect and defend their mercantile and economical interests in Denmark and Sweden. They would eventually control the trading routes in the border areas of the Union, and by exploiting the political chaos within the Union they would gain access and influence to the land trading routes for export and import within the Union and the shipping export routes in the Baltic Sea allowing them access to the Russian market through Finland and Estonia. The island of Gotland, with its tactical and important geographical position in the Baltic Sea became the key to the Nordic Union. Olof Axelsson (Tott) sailing under the Danish flag took possession of Gotland in 1449. Although technically a part of the Danish kingdom, in practice the island would remain independent and under the control of the Axelsson brothers until 1487 when the last surviving brother, Sir Ivar relinquished his rights to Gotland in favor of the Danish monarch, King Hans. The Axelsson brothers (Tott) would hold the key to The Nordic Union for almost four decades. Thus controlling the future of the union within the family by marriage, by political associations within and outside of the Union and most importantly by creating an economical empire based on personal family politics and border gentry aspirations.

This thesis provides a coherent theoretical account of the role of trust in strategic alliances from varied disciplinary perspectives and by establishing some common ground among these perspectives. Approaching the integration of the literature about trust and strategic alliances from the resource based view, the transaction cost view, the dialectical perspective, and the social network perspective is aimed at creating a new systematic explanatory scheme. The unique combination of these four perspectives provides overlapping explanations for strategic alliance behaviour and serves as a methodical device for analysing the dynamics of trust relationships. This theoretical-methodical foundation will serve as tool for sorting out and highlighting different research streams regarding the two key topics. An integrative framework of the notion of trust in strategic alliances is built around the key issue “culture of trust”. The culture of trust is addressed, because one of the main findings will be that collaborative relationships require some minimum social base with trust as its constitutive element. Arguments will be provided that inter-organizational ventures characterized by high interdependence, require the trust mechanism to make leadership effective. The tension between trust and control in strategic alliances is discussed and attention is drawn to the possibilities and key abilities of leaders in establishing trust as a constitutive element in strategic alliances.

The ecology behind evolutionary diversification is a well studied area of research, whereas the effects of evolution on ecosystems get little attention. In line with ecological theory, evolutionary diversification of a species could influence different ecosystem aspects such as food web composition, energy flow, nutrient cycling etc. The main objective of this study was to investigate whether two diverging ecotypes (reed and chara) of Asellus aquaticus differ regarding their role in two aquatic ecosystem processes: decomposition of terrestrial leaves and grazing of periphyton. Their role in ecosystem process as well as treatment effects on fitness, measured as growth and survival, were investigated in a laboratory experiment with various levels of intra-specific competition and inter-specific interactions with the amphipod Gammarus pulex. The isopods were collected from two Swedish lakes: Lake Tåkern and Lake Fardume. These two lakes represent different history of ecotype divergence. The experimental design consisted of 2-L aquaria, each providing elm leaves (Ulmus glabra), oak leaves (Quercus roburleaves) and periphyton as food sources. Ten treatments with five replicates were applied for each lake and the experiment lasted for four weeks. The study showed that there was no significant difference between chara and reed ecotype in their functional role. However, the rate of ecosystem processes per individual decreased in competitive interactions. In high density, decomposition per dry weight consumer was low and total algae biomass was high at the end of four weeks due to intra-specific competition. Moreover, ecosystem processes were lowest in inter-specific competition between Gammarus pulex and each ecotype. Present study also shows that ecotypes from the different lakes, having different history, had different responses to mortality and growth.

An architectural framework is proposed to secure the data link layer (Layer 2) in Internet protocol (IP) over Ethernet networks. In this architecture, a new security inter-layering concept, incorporating cryptographic Layer 2 identities, is introduced. Instead of traditional media access control (MAC) addresses, secure and flexible data link layer identifiers are utilized to securely bind Layer 2 and upper layers. In addition, to create security parameters and negotiate identifiers at the data link layer, a key establishment protocol is presented. Moreover, this architecture incorporates the IEEE 802.1AE standard (MACsec) and uses a key hierarchy similar to the IEEE 802.11i standard for future compatibility of wired and wireless networks. Finally, we provide a security analysis of the new data link layer security architecture.

In this thesis, we investigate a wireless communications system with distributed transmit antennas. Under such system scenario, the received signal has multiple carrier frequency offsets (CFOs) since each transmitter has its own oscillator, leading to serious inter-carrier interference (ICI) at the receiver end. Therefore, an ICI self-cancellation scheme is proposed in this thesis, where two different relay nodes use different sub-carriers. When the signals from different relay nodes are combined at the destination node, the ICI self-cancellation can be achieved. In addition, the quality of the received signal can be further improved if the residual CFO can be properly compensated. Traditionally, the medium value of the various CFOs is taken for compensation because of its simplicity. However, a medium value does not result in the optimal performance. In this thesis, a close form expression of optimal CFO is derived to maximize the average signal to interference power ratio. It is shown that the optimal CFO compensation is a function of channel state and individual CFOs. Simulation experiments are conducted to investigate the performance of the proposed scheme. It is shown that the system bit error rate can be substantially improved when the CFO is less than 0.3 subcarrier spacing.

In recent years, relay communication has been proved to achieve the transmis-sion diversity order with space-time block coding (STBC). Most research assumedthat the relay nodes are in perfect synchronization. However, in actual, becausethe transmitting time at each relay is different, the signals from different relays received at destination will interfere with each other. Inter-symbol interference (ISI) iscaused. Besides, the time synchronization error will reduce orthogonality of space-time block coding and result in serious performance degrade. This thesis proposes a time delay compensation method by using Fourier transform and Least Square(LS)estimation method. The destination node can utilize the estimated time delay tosynchronize the received signal. Then, the space-time coding will maintain orthogonality at the receiver. Simulation results show that the proposed method caneffectively improve the performance of cooperative networks when imperfect timesynchronization exists.