The Plasma Impedance Probe (PIP) is an electronic instrument that measures the impedance of a dipole antenna immersed in a plasma environment. Measurements made by the PIP provide valuable information regarding the plasma environment. Knowledge of ionospheric plasma density and density disturbances is required to understand radio frequency communication with satellites. The impedance curve provides us with significant plasma characteristics such as the electron-neutral collision frequency and plasma electron density. The work proposed here is a transistor-level implementation of the analog front-end, the non-inverting amplifier that is used to drive the antenna. The antenna immersed in plasma is excited with a sinusoidal/pulse stimulus and the output from the non-inverting configuration is fed into the difference amplifier. In the difference amplifier the output signal from the non- inverting amplifier is subtracted from the original stimulus and then fed into a high-speed pipeline data converter. The entire analog and mixed signal components are integrated on a single chip. The obvious advantages with this design are that it eliminates several sources of analog signal processing errors, thereby improving stability. A Fast Fourier Transform (FFT) is then applied on the sampled input stimulus as well as the processed signal. The input voltage FFT is then divided by the current FFT to obtain the antenna impedance. The FFT method helps in reducing transient errors and improves noise immunity of the system. The antenna impedance span curves over the frequency range from 100 kHz to 20MHz. The approach for the tranistor-level design is implementing short-channel design tech- niques using the gm/ID method. This is the primary focus of the thesis where the emphasis has been on using a simple and intuitive method to design the front-end amplifier in the TSMC .35 um technology. The design specifications for this amplifier are derived from the system-level simulations. The transition from a Printed Circuit Board (PCB)-based design to System on Chip (SOC) implementation is explored. This makes the design components highly specific to the application. The following are the design approaches used for the analog front-end design. * A detailed study of the various factors affecting the PIP instrument measurement capabilities from the previous works. * System-level simulation of the the entire PIP system to completely characterize the analog front-end. * Exploration of the possible design topologies for the transistor-level implementation. * A novel method of analog amplifier design using the gm/ID methodology. Miniaturization of the instrument and using a pulse-based measurement scheme also offer an immediate benefit to sounding rocket missions. The reduction of power, mass, and volume will enable the instrument to be flown on many more sounding rockets than at present. The faster measurement is especially valuable since the ionospheric plasma changes in character most rapidly with altitude.

A precise simulation requires a large amount of input data such as geometrical descriptions of the crystal structure, the external forces and loads, and quantitative properties of the material. Although some powerful applications already exist for research purposes, they are not widely used in education due to complex structure and unintuitive operation. To cater to the generic user base, a front-end application for material simulation software is introduced. With a graphic interface, it provides a more efficient way to conduct the simulation and to educate students who want to enlarge knowledge in relevant fields. We first discuss how we explore the solution for the front-end application and how to develop it on top of the material simulation software developed by mechanical engineering lab from Georgia Tech Lorraine. The user interface design, the functionality and the whole user experience are primary factors determining the product success or failure. This material simulation software helps researchers resolve the motion and the interactions of a large ensemble of dislocations for single or multi-layered 3D materials. However, the algorithm it utilizes is not well optimized and parallelized, so its performance of speedup cannot scale when using more CPUs in the cluster. This problem leads to the second topic on scientific computing, so in this thesis we offer different approaches that attempt to improve the parallelization and optimize the scalability.

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<p>More people are connecting to the Internet, by using computers and other devices. At the same time web applications are replacing locally installed applications. This makes web application usability an interesting and important subject.</p><p>The aim of this thesis was to find a set of usability recommendations and guidelines specifically suited for web-based applications. The guidelines were derived both from studies on how web applications and regular web sites should be designed, usability studies for locally installed applications as well as more general usability and interaction design guidelines.</p><p>A prototype was created based on the list of guidelines. The prototype was then evaluated from a usability perspective, using heuristic evaluation with Nielsen’s 10 usability heuristics, to test the validity of the guidelines.</p><p>The results of the evaluation says that while the list of guidelines can be used to help creating usable web applications, following the guidelines is not alone a mean of getting rid of all usability problems.</p>

More people are connecting to the Internet, by using computers and other devices. At the same time web applications are replacing locally installed applications. This makes web application usability an interesting and important subject. The aim of this thesis was to find a set of usability recommendations and guidelines specifically suited for web-based applications. The guidelines were derived both from studies on how web applications and regular web sites should be designed, usability studies for locally installed applications as well as more general usability and interaction design guidelines. A prototype was created based on the list of guidelines. The prototype was then evaluated from a usability perspective, using heuristic evaluation with Nielsen’s 10 usability heuristics, to test the validity of the guidelines. The results of the evaluation says that while the list of guidelines can be used to help creating usable web applications, following the guidelines is not alone a mean of getting rid of all usability problems.