Data query operations inside programming languages presently perform their functions through the use of domain-specific, declarative expressions and by way of course-grain, API library calls. These methods of operation are practiced by relational databases as well as semistructured XML data stores. Layers of translation, which are necessary to transform data and instructions from the domain of programming languages to data query systems, negtatively effect the performance of data query operations. Skuery resolves this impedance by adopting XML as a native data type with a native representation (SXML). Likewise, query operations are defined in a general purpose programming language (Scheme in this case) not in an external data query environment. Skuery increases programmer productivity by abstracting layers of translation and unifying computational and data query operations under the auspices of a general purpose programming language.

When experimental units exhibit a smooth trend over time or in space, random allocation of treatments may no longer be appropriate. Instead, systematic run orders may have to be used to reduce or eliminate the effects of such a trend. The resulting designs are referred to as trend-free designs. We consider here, in particular, linear trend-free designs for factorial treatment structures such that estimates of main effects and two-factor interactions are trend-free. In addition to trend-freeness we incorporate a general cost structure and propose methods of constructing optimal or near-optimal full or fractional factorial designs. Building upon the generalized foldover scheme (GFS) introduced by Coster and Cheng (1988) we develop a procedure of selection of foldover vectors (SFV) which is a construction method for an appropriate generator matrix. The final optimal or near-optimal design can then be developed from this generator matrix. To achieve a reduction in the amount of work, i.e., a reduction of the large number of possible generator matrices, and to make this whole process easier to use by a practitioner, we introduce the systematic selection of foldover vectors (SSFV). This method does not always produce optimal designs but in all cases practical compromise designs. The cost structure for factorial designs can be modeled according to the number of level changes for the various factors. In general, if cost needs to be kept to a minimum, factor level changes will have to be kept at a minimum. This introduces a covariance structure for the observations from such an experiment. We consider the consequences of this covariance structure with respect to the analysis of trend-free factorial designs. We formulate an appropriate underlying mixed linear model and propose an AIC-based method using simulation studies, which leads to a useful practical linear model as compared to the theoretical model, because the theoretical model is not always feasible. Overall, we show that estimation of main effects and two-factor interactions, trend-freeness, and minimum cost cannot always be achieved simultaneously. As a consequence, compromise designs have to be considered, which satisfy requirements as much as possible and are practical at the same time. The proposed methods achieve this aim. / Ph. D.

Long-term climatological data were used to evaluate the effectiveness of a drop/add management strategy to reduce groundwater use and effluent discharge in catfish ponds in the southeast U.S.. A drop/add approach is based on the creation of a storage volume in the pond for rainfall collection. The storage volume is created by allowing water level in the pond to decrease until some minimum level is reached. When the minimum level is reached, the pond is partly refilled, leaving the remaining volume available to capture incident precipitation. In this way, the role of precipitation in the water budget is increased. In the process, groundwater use and effluent release both become smaller. The data consisted of 45 year precipitation and evaporation records from Fairhope, AL; Clemson, SC; Stoneville, MS, Stuttgart, AR; and Thomsons, TX. The data were used in a water balance levee pond model that included precipitation, evaporation, infiltration, overflow, groundwater pumping, and draining. The model appeared to indicate that the drop/add management scheme is an effective strategy to reduce groundwater use and effluent discharge. The simulated results showed that variation of climate in the southeast U.S. was an important determinant of performance of the drop/add management scheme. At locations with positive P-0.8E, zero groundwater use could be achieved with low drop depths. At location with negative P-0.8E, zero groundwater use could be achieved for about 50% of the 45 simulated years. The model also indicated that effluent discharge cannot be avoided at most locations except at location with very low (negative) P-0.8E. The model also indicated that 65 to 100% of annual precipitation (depending on the P-0.8E?s of the locations) can be captured and used in the ponds. Rainwater contribution to the total water budget ranged from 90 to 100%. The sensitivity analysis showed that model sensitivity to pan coefficient and infiltration rate was affected by infiltration rate and pond water storage capacity (drop depth). The model was more sensitive to pan coefficient rather than to infiltration rate at lower infiltration rates and vice-versa.Both sensitivities of the model, however, increased when pond water deeper storage capacity was used.

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Zwei numerische Verfahren, das Upstream- und das MacCormack-Verfahren, werden im Hinblick auf ihre Eigenschaften bei der Lösung unterschiedlicher Advektionsprobleme verglichen. Das Letzere, welches eine Genauigkeit zweiter Ordnung liefert, wird in den Impulsadvektionsteil des numerischen Strömungsmodells MISKAM implementiert und anhand von Sensitivitätsstudien mit dem Upstream-Verfahren verglichen. Anschließend findet eine Modellevaluierung mit Hilfe von Datensätzen, welche am Hamburger Grenzschichtwindkanal erzeugt wurden, statt. Das Verfahren zeigt bei stabiler thermischer Modellschichtung signifikant veränderte Ergebnisse, deutlich zeigt sich die verringerte numerische Diffusion, vor allem im Bereich von Ecken und Kanten eines Hindernisses. / Two numerical schemes are compared concerning their numerical abilities when solving different advection problems. MacCormack\'s scheme which is of second order accuracy is implemented in the numerical flow model MISKAM in order to calculate the advection of momentum. It is compared to the upstream scheme with the help of sensitivity studies and with a model evaluation using wind tunnel data from the University of Hamburg. The scheme shows for stable thermical stratification significant differences near the edges of obstacles that result mainly from the reduced numerical diffusion which was the major problem when using the upstream scheme.

With growing trend in "cloud computing" and increase in the data moving into the Internet, the need to store large amounts of data by service providers such as Google, Yahoo and Microsoft has increased over time. Now, more than ever, there is a need to efficiently and securely store large amounts of data. This thesis presents an implementation of a Ramp Scheme that confidentially splits a data file into a configurable number of parts or shares of equal size such that a subset of those shares can recover the data entirely. Furthermore, the implementation supports a threshold for data compromise and data verification to verify that the data parts have not been tampered with. This thesis addresses two key problems faced in large-scale data storage, namely, data availability and confidentiality.

In general we know that the fixed point locus of a 1-dimensional additive linear algebraic group,G_{a}, action over a complete nonsingular variety is connected. In thesis, we explicitly identify a subset of the G_{a}-fixed locus of the punctual Hilbert scheme of the d points,Hilb^{d}(P^{2} / 0),in P^{2}. In particular we give an other proof of the fact that Hilb^{d}(P^{2} / 0) is connected.

The budget system is one of the important tools in the management accounting control system. However, in the budget goal setting process, budgeting managers may insert slack into their budgets. Budget slack will erode the effectiveness of the budget system. Agency researchers recognize that well-designed contracts can be used to solve this incentive problem. Therefore, truth-inducing schemes are widely discussed and analyzed. However, many empirical studies report that such schemes can decrease, but not eliminate slack completely. In the meanwhile, they can not increase performance. This study points out that the parameters of the schemes are not well-designed, therefore, the effectiveness to induce subordinates to disclose private information and increase performance is of failure. This paper analyses the relationship among parameters of the truth-inducing pay scheme, risk preference and budget slack by Minimax law under uncertainty, and points that this scheme will lose its effectiveness under some condition. At the meanwhile, this thesis also explains how to design a compensation contract to provide a reference for practical application.

The overall aim with this thesis is to create a broader understanding of how the EMS tool works in local authorities. This means to study whether EMS is a useful tool for managing the environmental impact from the local authorities' activities and by highlighting its strengths and weaknesses as a tool. EMS is a tool that is used on a voluntary basis that aims at improving organisations' environmental performance. There are several standards for designing EMSs; however, this thesis focuses on EMSs designed according to the principles of the international standard ISO 14001 and the EU regulation Eco-Management and Audit Scheme (EMAS). The standards are based on a wide range of requirements. If these requirements are fulfilled, the organisation can choose to get its EMS certified by a third party. The EMS tool is frequently used in the private sector, and it is sometimes argued that it is designed for private (industrial) organisations. However, local authorities worldwide have shown an increased interest in EMSs since the mid 1990s. The EMS use in the private sector has been subject to some critique. For example, there is a risk that the tool is used only to get another certificate in order to increase their legitimacy, which means that there is a risk that the environmental issues are neglected. Until now, little academic research has been conducted concerning EMS use in local authorities. Therefore, it is interesting to study what approaches local authorities have to EMSs. Mainly Swedish local authorities have been studied for this thesis. Many Swedish local authorities have been using EMSs for a fairly long time, which means that they have a certain amount of experience from this using tool. The local authorities' approaches to EMS use have been studied from several perspectives using postal surveys, interviews, and case study methodology. This means that the research has a strong empirical foundation. The EMS use in Swedish local authorities is fairly common, since almost half of them are in the process of implementing EMSs in all or some of their departments. The main reason for implementing EMSs is to improve the structure of their environmental management. The local authorities often use ISO 14001 and/or EMAS as inspiration and design the EMSs according to their local conditions and ambitions, thus certification of the EMSs is seldom an aim. Although many local authorities seem to use EMSs in a reflective and sensible way, several barriers or difficulties - for example, maintaining continuity and ensuring follow-up of the environmental improvements - have been discovered. Furthermore, the EMSs that are being implemented often exclude environmental impact related to their exercise of authority since it is difficult and abstract. Including environmental impact related to these activities is often seen as a matter of maturity. To develop the organisations' EMSs, internal and external communication and interaction is experienced as very important. Such issues contribute to the EMS maturity processes, since the local authorities find new inspiration, knowledge, and motivation to further develop the EMS processes and, as a consequence, improve their environmental performance.

Code-based cryptography is an area of classical cryptography in which cryptographic primitives rely on hard problems and trapdoor functions related to linear error-correcting codes. Since its inception in 1978, the area has produced the McEliece and the Niederreiter cryptosystems, multiple digital signature schemes, identification schemes and code-based hash functions. All of these are believed to be resistant to attacks by quantum computers. Hence, code-based cryptography represents a post-quantum alternative to the widespread number-theoretic systems. This thesis summarizes recent developments in the field of code-based cryptography, with a particular emphasis on code-based signature schemes. After a brief introduction and analysis of the McEliece and the Niederreiter cryptosystems, we discuss the currently unresolved issue of constructing a practical, yet provably secure signature scheme. A detailed analysis is provided for the Courtois, Finiasz and Sendrier signature scheme, along with the mCFS and parallel CFS variations. Finally, we discuss a recent proposal by Preetha et al. that attempts to solve the issue of provable security, currently failing in the CFS scheme case, by randomizing the public key construct. We conclude that, while the proposal is not yet practical, it represents an important advancement in the search for an ideal code-based signature scheme.