The mechanical properties of a polymer represent the critical characteristics to be considered when determining the applications for it. The same polymer processed with different methods can exhibit different mechanical properties. The purpose of this study is to investigate the difference in mechanical properties of the selected polymers caused by different processing techniques and conditions. Three polymers were studied, including low density polyethylene (LDPE), polypropylene (PP), and NEXPRENE® 1287A. Samples were processed with injection molding and compression molding under different processing condition. Tensile and DMA tests were performed on these samples. The acquired data of strain at break from the tensile tests and storage modulus from the DMA were utilized to calculate brittleness. Calculated brittleness values were used to perform analysis of variance (ANOVA) to investigate the statistical significance of the processing technique and condition. It was found that different processing techniques affect the brittleness significantly. The processing technique is the major factor affecting brittleness of PP and NEXPRENE, and the processing temperature is the major factor affecting brittleness of LDPE.

This study was conducted to investigate the requirement for sperm processing in microsurgical subzonal placement of sperm in rabbit oocytes. Fertilization rates with standard in vitro fertilization and microsurgical subzonal sperm placement were found to be similar (56 and 55%) when sperm treated with high-ionic strength Brackett's defined inedium to initiate capacitation were used. Statistically significant reductions in fertilization rates for both standard in vitro fertilization and subzonal placement were noted when twice-washed spermatozoa were used. Initiation of capacitation of spermatozoa results in higher fertilization results even when the zona pellucida is bypassed during fertilization.

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This work is concerned with the prediction of short (SGF) and long glass fiber (LGF) orientation in a center-gated disk and end-gated plaque injection molding test geometry using a simulation method that has not been attempted previously. Previous work has used assumptions to simplify the fiber orientation geometry (assuming a thin cavity) or flow field (neglecting fountain flow and entry regions). LGF orientation is predicted in a center-gated disk injection molding geometry including the advancing front and simulating the sprue and gate region (SGM method) so that no assumption about fiber orientation at the mold entrance has to be made. Using a semi-flexible fiber model and orientation parameters obtained through rheology, increased agreement was found between predicted and experimentally obtained values of orientation using the SGM method and a semi-flexible fiber model than was found using a Hele-Shaw approximation. The SGM method was applied to the end-gated plaque to predict SGF orientation both along and away from the centerline using an objective (reduced strain closure model) and non-objective (strain reduction factor model) orientation model. The predicted values of the strain reduction factor model showed reasonable agreement with experimentally obtained values of orientation throughout the three-dimensional cavity when using orientation parameters fit to experimental orientation data. Furthermore it was found that the objective model predicted results very similar to the non-objective model suggesting that objectivity may not play a role in predicting orientation in more complex geometries such as an end-gated plaque. Finally, the SGM method was applied to the end-gated plaque geometry to predict LGF orientation using a rigid and semi-flexible fiber model. It was found that the SGM method and the semi-flexible fiber model provides orientation predictions that are similar to experimentally obtained values of orientation. / Ph. D.

The extent of embedded systems' role in modern life has continuously increased over the years. Moreover, embedded systems are assuming highly critical functions with security requirements more than ever before. Electromagnetic fault injection (EMFI) is an efficient class of physical attacks that can compromise the immunity of secure cryptographic algorithms. Despite successful EMFI attacks, the effects of electromagnetic injection on a processor are not well understood. This includes lack of solid knowledge about how EMFI affects the circuit and deviates it from proper functionality. Also, effects of EM glitches on the global networks of a chip such as power, clock and reset network are not known. We believe to properly model EMFI and develop effective countermeasures, a deeper understanding of the EM effect on a chip is needed. In this thesis, we present a bottom-up analysis of EMFI effects on a RISC microprocessor. We study these effects at three levels: at the wire-level, at the chip-network level, and at the gate-level considering parameters such as EM-injection location and timing. We conclude that EMFI induces local timing errors implying current timing attack detection and prevention techniques can be adapted to overcome EMFI. To further validate our hypothesis, we integrate a configurable timing sensor into our microprocessor to evaluate its effectiveness against EMFI. / Master of Science

This study examines the effect of varying injectant molecular weight on the penetration of transverse injection jets into a supersonic crossflow. The injectants considered here are methane (W=16.04), air (W=28.97) and carbon dioxide, (W=44.01). These results augment the previous results obtained at Virginia Tech for helium (W=4.00) injection under the same test conditions to provide a very wide range of molecular weights. Second, since shocks are ubiquitous in scramjet combustors, their influence on penetration and mixing was also studied by arranging for an oblique shock to impinge near the injection station. The cases of a shock impinging upstream and downstream of the injector were both examined. One can anticipate an important influence of molecular weight here also because of the importance of density gradients on the generation of vorticity by baroclinic torque. Increasing molecular weight was found to increase penetration in general, as well as increase the lateral spreading of the plume. The majority of the data shows a weak dependency of the jet size on molecular weight, but there are indications that under certain circumstances large changes in the flow structure may occur due to molecular weight effects. The addition of an impinging shock is found to increase mixing and decrease penetration and plume size, especially with the shock impinging downstream of the injector. / Master of Science

Histotripsy is a nonthermal ultrasound therapy used to treat cancer noninvasively by tissue mechanical fractionation with cavitation bubble clouds. Histotripsy is conducted through focused ultrasound transducers, where the piezoceramic (PZT) plate or disc, which emits the ultrasound wave, is the fundamental unit of the transducer. For modular prototype histotripsy designs, these PZTs are housed in a 3D printed focused lens. However, 3D printing transducer components can be time consuming and expensive when scaling up manufacturing, and 3D printing is limited in material selection for transducer applications. This thesis investigates the use of a novel fabrication process for prototype focused ultrasound transducers, injection molding, with an in-house benchtop injection molding machine. Acoustic material properties for investigated injection molded materials, ABS, GPPS, 30% glass filled nylon, nylon 6/6, and nylon 101, are quantified experimentally. Single elements are constructed with injection molded lenses made from ABS, 30% glass-filled nylon, nylon 6/6, and nylon 101 on an in-house benchtop machine. Results show that injection molding is a novel feasible method for applications in focused ultrasound devices and the investigated plastics have favorable properties for developing prototype histotripsy transducers, comparable to 3D printed transducer housings. Future work aims to apply injection molding to various transducer designs and additional materials for focused ultrasound therapy devices. / Master of Science / Histotripsy is a cancer therapy that can noninvasively treat tumors without surgery. This is done through devices called focused ultrasound transducers which emit ultrasound waves to administer treatment to ablate tumors. These transducers are constructed using 3D printing methods, but this can be limiting when scaling up manufacturing or in material selection for transducer applications, therefore additional fabrication methods are needed. This thesis presents injection molding as a novel method for making transducer components with an in-house benchtop injection molding machine. Five plastic materials are investigated to determine ultrasound properties that would identify preferred transducer materials. Single element transducers are made from injection molded materials, tested, and compared with 3D printed single element transducers. Results of this thesis show that injection molding is a feasible manufacturing method capable of producing transducers for histotripsy, and researched materials have favorable properties for this application. In future research, additional injection molded materials should be investigated and multiple transducer designs created for injection molding fabrication. These injection molded transducers can be applied to histotripsy or applied to other focused ultrasound therapies.

Fault injection attacks are a powerful technique that intentionally induces faults during computations to leak secret information. This thesis studies the fault injection attack techniques. The thesis first categorizes various fault attack methods by fault model and fault analysis and gives examples of the various fault attacks on symmetric key cryptosystems and public key cryptosystems. The thesis then demonstrates fault injection attacks on RSA-CRT and constant time CSIDH. The fault attack consists of two main components: fault modeling, which examines methods for injecting faults in a target device, and fault analysis, which analyzes the resulting faulty outputs to deduce secrets in each cryptosystem. The thesis aims to provide a comprehensive survey on fault attack research, directions for further study on securing real-world cryptosystems against fault injection attacks, testing fault injection attacks with RSA-CRT, and demonstrate and evaluate fault injection attacks on constant time CSIDH. / Master of Science / Fault injection attacks are attacks where the attackers intentionally induce the fault in the device during the operation to obtain or recover secret information. The induced fault will impact the operation and cause the faulty output, providing the information to attackers. Many cryptographic algorithms and devices have been proven vulnerable to fault injection attacks. Cryptography is essential nowadays, as it is used to secure and protect confidential data. If the cryptosystem is broken, many system today will be compromised. Thus, this thesis focus on the fault injection attacks on the cryptosystems. This thesis introduces the background of fault injection attacks, categorizes them into different types, and provides examples of the attacks on cryptosystems. The thesis studies how the attacks work, including how the attack induces the fault in the device and how the attack analyzes the fault output they obtained. Specifically, I examine how these attacks affect two commonly used encryption methods: symmetric key cryptography and public key cryptography. Additionally, I implement the fault injection attack on RSA-CRT and emph{Commutative Supersingular Isogeny Diffie-Hellman}~(CSIDH). This research aims to understand the potential attack method on different cryptosystems and can explore mitigation or protection in the future.