Master of Science

thesisThis thesis designs, implements, and evaluates modular Open Core Protocol (OCP) interfaces for Intellectual Property (IP) cores and Network-on-Chip (NoC) that re- duces System-On-Chip (SoC) design time and enables research on di erent architectural sequencing control methods. To utilize the NoCs design time optimization feature at the boundaries, a standardized industry socket was required, which can address the SoC shorter time-to-market requirements, design issues, and also the subsequent reuse of developed IP cores. OCP is an open industry standard socket interface speci cation used in this research to enable the IP cores reusability across multiple SoC designs. This research work designs and implements clocked OCP interfaces between IP cores and On-Chip Network Fabric (NoC), in single- and multi- frequency clocked domains. The NoC interfaces between IP cores and on-chip network fabric are implemented using the standard network interface structure. It consists of back-end and front-end submodules corresponding to customized interfaces to IP cores or network fabric and OCP Master and Slave entities, respectively. A generic domain interface (DI) protocol is designed which acts as the bridge between back-end and front-end submodules for synchronization and data ow control. Clocked OCP interfaces are synthesized, placed and routed using IBM's 65nm process technology. The implemented designs are veri ed for OCP compliance using SOLV (Sonics OCP Library for Veri cation). Finally, this thesis reports the performance metrics such as design target frequency of operation, latency, area, energy per transaction, and maximum bandwidth across network on-chip for single- and multifrequency clocked designs

Discrete Moving Target Defense Application and Benchmarking in Software-Defined Networking

Moving Target Defense is a technique focused on disrupting certain phases of a cyber-attack. The static nature of the existing networks gives the adversaries an adequate amount of time to gather enough data concerning the target and succeed in mounting an attack. The random host address mutation is a well-known MTD technique that hides the actual IP address from external scanners. When the host establishes a session of transmitting or receiving data, due to mutation interval, the session is interrupted, leading to the host’s unavailability. Moving the network configuration creates overhead on the controller and additional switching costs resulting in latency, poor performance, packet loss, and jitter. In this dissertation, we proposed a novel discrete MTD technique in software-defined networking (SDN) to individualize the mutation interval for each host. The host IP address is changed at different intervals to avoid the termination of the existing sessions and to increase complexity in understanding mutation intervals for the attacker. We use the flow statistics of each host to determine if the host is in a session of transmitting or receiving data. Individualizing the mutation interval of each host enhances the defender game strategy making it complex in determining the pattern of mutation interval. Since the mutation of the host address is achieved using a pool of virtual (temporary) host addresses, a subnet game strategy is introduced to increase complexity in determining the network topology. A benchmarking framework is developed to measure the performance, scalability, and reliability of the MTD network with the traditional network. The analysis shows the discrete MTD network outperforms the random MTD network in all tests

A methodology to determine the functional workspace of a 6R robot using forward kinematics and geometrical methods

The work envelope of a robot does not capture the effect of tool orientation. Applications will require the tool to be at a certain orientation to perform the tasks necessary. It is therefore important to introduce a parameter that can capture the effect of orientation for multiple robots and configurations. This is called the functional work space, which is a subset of the work envelope would capture the effect of orientation. This research discusses the development of establishing an assessment tool that can predict the functional work space of a robot for a certain tool-orientation pair thus aiding in proper tool, tool path, fixture, related configuration selection and placement. Several solutions are studied and an analytical and a geometric solution is presented after a detailed study of joint dependencies, joint movements, limits, link lengths and displacements through visual, empirical and analytical approaches. The functional workspace curve for a manipulator with similar kinematic structure can be created using the geometrical solution discussed in this research. It is difficult to derive a general paradigm since different parameters such as, joint limits, angles and twist angles seem to have a different effect on the shape of the workspace. The geometrical solution employed is simple, easy to deduce and can be simulated with a commercial software package. Design decisions pertaining to configuration and reconfiguration of manipulators will benefit by employing the solution as a design/analysis tool. A case study involving an X-ray diffraction technique goniometer is presented to highlight the merits of this work

Evolution of Phosphotriesterases (PTEs): How bacteria can acquire new degradative functions

The promiscuity of enzymes has often been considered a vestige activity based on the broad substrate spectrum of their progenitors. As such, divergent enzymes can be used as a fingerprint to track their evolutionary history. In the presence of structural mimics of active site or binding site ligands and assisted by mutations in the associated binding site, this promiscuity contributes to acquisition of new catalytic functions. This phenomenon is often referred to as substrate-assisted gain-of-function and helps soil microbes to thrive on re-calcitrant xenobiotic molecules, hitherto unfamiliar to the microbial world. This review describes the evolution of organophosphorous hydrolases, which potentially and originally functioned as quorum-sensing ‘quenching’ lactonases and highlights their remarkable horizontal mobility within diverse bacterial species

A RELIABLE ROUTING MECHANISM WITH ENERGY-EFFICIENT NODE SELECTION FOR DATA TRANSMISSION USING A GENETIC ALGORITHM IN WIRELESS SENSOR NETWORK

Energy-efficient and reliable data routing is critical in Wireless Sensor Networks (WSNs) application scenarios. Due to oscillations in wireless links in adverse environmental conditions, sensed data may not be sent to a sink node. As a result of wireless connectivity fluctuations, packet loss may occur. However, retransmission-based approaches are used to improve reliable data delivery. These approaches need a high quantity of data transfers for reliable data collection. Energy usage and packet delivery delays increase as a result of an increase in data transmissions. An energy-efficient data collection approach based on a genetic algorithm has been suggested in this paper to determine the most energy-efficient and reliable data routing in wireless sensor networks. The proposed algorithm reduced the number of data transmissions, energy consumption, and delay in network packet delivery. However, increased network lifetime. Furthermore, simulation results demonstrated the efficacy of the proposed method, considering the parameters energy consumption, network lifetime, number of data transmissions, and average delivery delay

Salt effects on the mechanical properties of ionic conductive polymer: a molecular dynamics study

Functoinal polymers can be used as electrolyte and binder materials in solid-state batteries. This often requires performance targets in terms of both transport and mechanical properties. In this work, a model ionic conductive polymer system, i.e., poly(ethylene oxide)-LiTFSI, was used to study the impact of salt concentrations on mechanical properties, including different types of elastic moduli and the visoelasticity with both non-equilibrium and equilibrium molecular dynamics simulations. We found an encouragingly good agreement between experiments and simulations regarding the Young's modulus, bulk modulus and viscosity. In addition, we identified an intermediate salt concentration at which the system shows high ionic conductivity, high Young's modulus and short elastic restoration time. Therefore, this study laid down the groundwork for investigating ionic conductive polymer binders with self-healing functionality from molecular dynamics simulations

Clinico-pathological study of intradural extramedullary spinal tumors

Background: The intradural extramedullary tumours of the spine are one of the commonest tumours of the spine. Early diagnosis and surgical removal helps in best outcome. The objective of the study was to analyze the clinical presentation, imageology, resectability, to know the incidence of different types of tumours in intradural extramedullary compartment and to study the surgical outcome.Methods: This was a prospective study of 32 cases of intradural extramedullary tumours. The clinical presentation, imageology, resectability, histopathology, surgical outcome were studied. The patients were investigated with plain spinal radiography and MRI. All cases were treated surgically by posterior or posterolateral approaches. Outcome and complications were evaluated. They were followed up regularly and the results were analyzed. Ambulatory status was classified on admission by using Nurick-grading scheme.Results: The incidence of intradural extramedullary spinal tumours was 57.14%. Most of the tumours presented in the third decade (37.5%). Mean age of Presentation for meningioma was 36 years and for nerve sheath tumours was 39.5 years. The nerve sheath tumours contributed 35% followed by meningioma 28%. Nerve sheath tumours were found to be most commonly located in thoracic region (56%). Total excision of tumour was achieved in 87.7% cases.Conclusions: Nerve Sheath tumours and Meningiomas were the most common in intradural extramedullary spinal lesions and complete excision was possible in almost all cases. Prognosis was usually good, in spite of poor neurological status at the time of presentation.

High-order multistep asynchronous splitting methods (MASM) for the numerical solution of multiple-time-scale ordinary differential equations

Often one encounters dynamical systems containing a wide range of natural frequencies. These multiple-time-scale systems, which are modeled using stiff ordinary differential equations, are well known to present a significant challenge in obtaining a numerical solution efficiently. Multiple-time-scale systems can be broadly classified into two classes: (1) systems with well-separate discrete time scales, such as molecular dynamic simulations and electrical networks, and (2) systems with a continuously-distributed range of time scales, such as aerosol dynamics, multiscale structural dynamics and turbulent fluid flow. For the numerical simulation of systems with well-separated discrete time scales one can frequently average over the fast time scales, either analytically or numerically. This results in effective models with only slower time scales and allows efficient numerical simulations with large timesteps. In cases where this is not possible, either due to system complexity or the fact that there is simply a wide range of timescales with no clear scale separation, such as the continuously-distributed time scales systems, it has traditionally been necessary to simulate the entire system at the rate of the fastest timescale, which can be very expensive. To efficiently simulate multiple-time-scale systems, many researchers have developed multiple-time-step numerical integration methods, where more than one timestep are used. These advance different components of the system forward in time at different rates, so that faster components can use small timesteps, while slower components can use large timesteps, resulting in lower computational cost. Most multiple-time-step integrators only apply to systems with discrete time scales, where subcycling methods, mollified methods, and r-RESPA are good examples. In addition, these methods which have several numerical timesteps require that timestep ratios be integer multiples of each other. In contrast, one family of multiple-time-step methods does not attempt to enforce any such restrictions, namely asynchronous integrators. These methods have incommensurate timesteps, such that all system components never synchronize at common time instants. This feature allows some asynchronous methods to be efficiently applied to systems with continuously-distributed time scales, where every time scale can have an appropriately-chosen numeral timestep. However, currently known asynchronous methods are at most second-order accurate and are known to suffer from resonance instabilities, severely limiting their practical efficiency gain relative to their synchronous counterparts. In the present work, a new family of high-order Multistep Asynchronous Splitting Methods (MASM) is developed, based on a generalization of both classical linear multistep methods and the previously-known Asynchronous Splitting Methods (ASMs). These new methods compute high-order trajectory approximations using the history of system states and force vectors as for linear multistep methods, while at the same time allowing incommensurate timesteps to be used for different system components as in ASMs. This allows them to be both high-order and asynchronous, and means that they are applicable to systems with either discrete time scales or continuously-distributed time scales. Consistency and convergence are established for these new high-order asynchronous methods both theoretically and via numerical simulations. For convergence, the only requirement is that the ratio of smallest to largest timestep remains bounded from above as the timesteps tend to zero. For a sufficiently regular ODE systems, an $m$-step MASM can achieve m^th order accuracy, which is proven analytically and then validated using numerical experiments. Numerical simulations show that these methods can be substantially more efficient than their synchronous counterparts. Given that appropriate timesteps are chosen, the efficiency gain using MASM compared to synchronous multi-step methods largely depends upon the force field splitting used. MASM is proven to be a stable method, provided it is convergent. The stability criterion also strongly depends upon the splitting of the force field chosen. In case of linear systems for which the Jacobian of the force vector is diagonalizable, the force vector splitting can be classified into asynchronous splitting, where each eigen-component is lumped with one of the component force vector, and \emph{time scale splitting}, where an eigen-component is split between two or more component force vectors. Any force vector splitting is in general a combination of asynchronous splitting and time scale splitting, where some eigen-components are lumped with one of the component force vectors and other eigen-components are split between different component force vectors. For synchronous splitting we prove a stability condition with a bound essentially the same as for the corresponding synchronous multi-step method, while for time scale splitting we restrict the analysis to two-component systems and derive stability conditions for both conservative and non-conservative systems. Finally, we also present an efficient time step selection (TSS) strategy that can be employed while using MASM for numerically solving ODEs, yielding the TSS-MASM method. This time step selection strategy is based on an optimal equidistribution principle, where component timesteps are chosen so that the contribution from each split force field towards the local discretization error is equal. The efficiency gain is system dependent and splitting dependent and is investigated numerically. For strongly coupled systems such as a multi-scale spring mass damper, TSS-MASM has approximately the same efficiency as synchronous multistep methods, while for weakly coupled systems such as aerosol condensation, TSS-MASM is much more efficient