2012 UMKC Theses - Freely Available Online
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Item Beamsteering and nullsteering in interference aware wireless networks with point to point beamforming(University of Missouri--Kansas City, 2013-03-19) Kashyap, Anudhriti; Beard, CoryThe concept of beamforming and beamsteering has been gathering immense popularity since the idea's inception. Many in the field of Wireless Communication and in the defense community have tried and succeeded in utilizing the benefits of beamforming and beamsteering with directional antennas. With the increasing popularity of decentralized adhoc networks, it only becomes necessary that the concept of beamsteering be formulated with respect to the network that is being studied. In relation to RF Engineering, the idea of beamsteering has been studied and explored diversely, by proposing beamsteering/ nullsteering algorithms pertaining to Digital Signal Processing. We however, make an attempt to understand beamsteering and nullsteering from the perspective of the physical layer of an Ad hoc network. Hence, it becomes essential that several network parameters like Signal to Interference Ratio, and contention in between individual connections be considered along with the RF parameters like antenna beamwidth, mainlobe and sidelobe gains, Relationship between sidelobes and nulls, Positions of sidelobes and nulls with change in the beamwidth and the number of elements in the directional antenna array. All these different parameters generate a sequence of combinations of results and change the performance of the network accordingly. The crux of this thesis is the antenna pattern model that is consistent with a practical directional antenna pattern, with a mainlobe, several sidelobes and nulls. This antenna pattern is able to derive a network that is much more efficient than its predecessor models that did not use the nulls and sidelobes in their antenna patterns. An algorithm implemented in this thesis shows the vast improvement in the network efficiency, when the different network entities use beamsteering and the alignment of nulls along interfering nodes. It is noticeable that the performance of the network improves by a factor of almost 30 percent due to the implementation of beamsteering as compared to only alignment of nulls along interfering nodes; and by a factor of 37 percent when compared to a model where no Sidelobes and nulls are considered.Item Managing malicious transactions in mobile database systems(University of Missouri--Kansas City, 2012) Singh, Abhiruchi; Kumar, Vijay, 1946-Database security is one of the most important issues for any organization, especially for financial institutions such as banks. Protecting database from external threats is relatively easier and a number of effective security schemes are available to organizations. Unfortunately, this is not so in the case of threats from insiders. Existing security schemes for such threats are some variation of external schemes that are not able to provide desirable security level. As a result, still authorized users (insiders) manage to misuse their privileges for fulfilling their malicious intent. It is a fact that most external security breaches succeed mainly with the help of insiders. An example for an insider is the Enron scandal of 2001 which led to bankruptcy of Enron Corporation. The firm was widely regarded as one of the most innovative, fastest growing and best managed business in the United States. When Enron filed for bankruptcy its share prices fall from US$90 to $1 causing a loss of nearly $11 billion dollar to its stakeholders. Financial officers and executives misled outside investors, auditors and Enron's board of directors about corporation's net income and liabilities. These insiders kept reported income and reported cash flow up, asset value inflated and liabilities off the book to meet Wall Street expectations. Enron's $63.4 billion in assets made it the largest corporate bankruptcy in American history at that time. Existing security policies are inadequate to prevent the attacks from insiders. Current database protections mechanisms do not fully protect occurrence of these malicious transactions. These requires human intervention in some form or other to detect malicious transactions. In a database, a transaction can affect the execution of the subsequesnt transactions thereby spreading the damage and hence making the attack recovery more complex. The problem of malicious attack becomes more pronounced when we are dealing with mobile database systems. This thesis proposes a solution to mitigate insider attack by identifying such malicious transactions. It develops a formal framework for characterizing mobile transaction by identifying essential components like order of data access, order of operations and user profile.Item Pressure-impulse diagrams using finite element analysis for reinforced concrete slabs subjected to blast loading(University of Missouri-Kansas City, 2012) Nalagotla, Jitesh Kumar Reddy; Thiagarajan, Ganesh, 1963-Reinforced concrete slab systems are widely used in protective structures designed to resist blast events. Blast events subject structures to high pressure and impulse loads. The magnitude of blast load experienced by a structural element is directly related to the exposed area. Hence protection of reinforced concrete slabs and walls, which constitute the maximum exposed area of a structure when subjected to blast loads, is of great importance. The main purpose of the project is to study the non-linear response of reinforced concrete slabs when subjected to impact and blast loading. Blast loading comprises of impulsive, dynamic and quasi-static loading conditions. And the performance of reinforced concrete slabs subjected to these loads is highly dependent upon the reinforcing steel provided in the slab. Hence a comprehensive analysis is performed on a representative slab panel with varying reinforcement. Due to the nature of the blast loading analysis method used influences the slab response significantly. Hence the slab response was predicted and compared using finite element (FE) and single degree of freedom (SDOF) methods. An advanced finite element modeling tool, LSDYNA and a commonly used SDOF analysis tool, SBEDS are employed for the purpose of analysis. A parametric analysis is conducted to develop Pressure-Impulse (PI) curves for different damage levels. Curve fit analysis was performed to characterize the PI curves generated from FE method. Conclusions and future work recommendations are presented for design of reinforced concrete slabs for blast protection based upon the research are presented and discussed.Item Maximizing throughput while maintaining fairness and priority in wireless ad-hoc networks(University of Missouri--Kansas City, 2012) Krishna, Neelabh; Beard, CoryAd-Hoc wireless network, not a new field of research, has been gaining a lot of popularity in recent years because of its applications in emergency rescue, surveying, military, sensor networking, entertainment and community wireless networking etc. A lot of research has been done on improving the performance and capacity of ad-hoc networks in that period of time. However, not much has been done in the analytical modeling of inter nodal interference and its effect on transmission patterns of wireless ad-hoc network. In our work we investigated and developed a contention based ad-hoc network to study the interference impact on network performance. In our model we represented these inter nodal conflicts using 'Conflict Graph or Conflict Matrix' and presented scheduling schemes to address issues like network throughput, fairness and QoS (priority) in a network. We particularly studied the transmission patterns in a network given a specific conflict graph which in turn depends on factors like number of nodes and their placement, area of coverage, type of antenna (unidirectional or omnidirectional) etc. We designed five scheduling schemes in order to provide solutions to issues like maximizing network throughput, fairness and priority using the concept of 'Transmit Groups', which are groups of nodes that are capable of transmitting together without any interference. For simulations, we have assumed a central entity which controls and schedules packet transmission from nodes. Using MATLAB simulations, we analyzed the throughput in hundreds of sample networks which differ based on number of nodes, number of conflicts and number of high priority nodes in the network. With the help of these results we not only proved that interference is an important factor in performance of wireless ad-hoc networks , but also its impact on different aspects of network depends on the number of nodes and number of conflicts. Based on the length of longest transmit group in a network and its variation with number of nodes, we calculated the maximum throughput possible. In our QoS schemes, we compared the success rate of achieving a pre assumed relative throughput by S-D pairs.Item A dual mode pulsed electro-magnetic cell stimulator(University of Missouri--Kansas City, 2012) Rizk, Hatem Ibrahim; León-Salas, Walter D. (Walter Daniel)This thesis presents the design and test of a dual-modality cell stimulator. The stimulator generates pulsing electric and magnetic fields at programmable rates and intensities. The target application is the stimulation of bone and muscle cells. While electric and magnetic stimulators have been reported before, this is the first device that combines both modalities. The ability of the dual stimulation to target bone and muscle tissue simultaneously has the potential to improve the therapeutic treatment of osteoporosis and sarcopenia. The device is fully programmable and easy to use and can run from a battery or a power supply. In-vitro tests show a 4% increase in protein synthesis 24 hours after the stimulation. These levels are comparable to heat shock stimulation.