Technology plays an increasingly significant role in the lives of children and adults, and it is imperative to understand if and how it impacts the development of psychological processes and the subsequent behaviors of preschool-aged children so that we can better understand how to navigate guidelines for use and interventions for overuse. To better understand the relationship between screen time use and a child’s social emotional development, it is important to consider parent time on screens, child time on screens, and any effects an older sibling in the home or parental gender may have on their development. This study gathered screen time usage rates from parents and their preschool-aged children and then measured the social emotional development of these children using an electronic version of the Devereux Early Childhood Assessment for Preschoolers, Second Edition (eDECA-2). Results were analyzed using sequential regression models and found child and parent screen time usage to be negatively associated with the social emotional development of the child. There were no moderating effects of the presence of an older sibling in the home. There were only moderating effects for parental gender when considering primary parents, which showed that when a male is a primary parent, increased parental and child screen time leads to a steeper decrease in behavioral concerns than when the primary parent is female. Additionally, categories of screen time usage were analyzed using multiple analyses of variance and showed that parents who used tool-based applications rated their children with higher levels of social emotional development. Results that analyzed the child’s categories of use did not show delineated differences between tool-based and non-tool-based applications.

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Modern computer systems require efficient data transfers involving memory in order to get the best possible performance. However, even the most optimized CPUs take too long to access memory regions, which takes time away from doing the typical computations that a CPU is designed to do. To solve this, Direct Memory Access (DMA) is used, which allows peripherals and other hardware accelerators, such as stand-alone DMA Controllers (DMACs), to read and write memory without CPU intervention. However, DMA introduces security problems in which attackers are able to leak data and overwrite critical system components by bypassing typical operating system security mechanisms. This thesis presents a case study to model as well as verify DMA device driver code in HOL4, which is an interactive theorem prover (ITP) used for machine-checked verification. This thesis verifies parts of Intel's IXGBE X550 device driver, which is a complex, 10 Gbit Network Interface Card (NIC). This verification takes the first significant step towards proving that the DMA device driver configures the DMA device such that it preserves memory isolation, which ensures that only memory that is intended to be readable and writable will be accessed. This thesis also provides a formal method to verify that a loop terminates under all possible cases. This can be used to further verify the correctness of a DMA driver. These contributions allow for the overall increased security of memory when using DMA device drivers that are verified by this approach, leading to the hindrance of attacks on systems utilizing DMA. / Master of Science / Modern computer systems use Direct Memory Accesses (DMAs) in order to offload the CPU from doing memory transfers. However, this poses the problem that the CPU is not able to monitor every memory access made through DMA. This can lead to attackers utilizing vulnerabilities in the device drivers used to perform DMA operations. This thesis addresses this problem by modeling and verifying properties of a device driver that will prove that the driver configures DMA such that it is isolated. This thesis also models and verifies a loop to ensure that it terminates, further verifying the correctness of a function in a device driver. These contributions are significant because they allow for increased security of a computer system's memory, reducing the likelihood of attacks.

An under-body blast (UBB) refers to the use of a roadside explosive device to target a vehicle and its occupants. During Operation Iraqi Freedom, improvised explosive devices (IEDs) accounted for an estimated 63% of US fatalities. Furthermore, advancements in protective equipment, combat triage, and treatment have caused an increase in IED casualties surviving with debilitating injuries. Military vehicles have been common targets of IED attacks because of the potential to inflict multiple casualties. Anthropomorphic test devices (ATDs) are mechanical human surrogates designed to transfer loads and display kinematics similar to a human subject. ATDs have been used successfully by the automotive industry for decades to quantify human injury during an impact and assess safety measures. Currently the Hybrid III ATD is used in live-fire military vehicle assessments. However, the Hybrid III was designed for frontal impacts and demonstrated poor biofidelity in vertical loading experiments. To assess military vehicle safety and make informed improvements to vehicle design, a novel Anthropomorphic Test Device (ATD) was developed and optimized for vertical loading. ATDs, commonly referred to as crash dummies, are designed to estimate the risk of injuries to a human during an impact. The main objective of this study was to develop and validate a Finite Element (FE) model of the ATD lower limb. / Master of Science / An under-body blast (UBB) refers to the use of a roadside explosive device to target a vehicle and its occupants. During Operation Iraqi Freedom, improvised explosive devices (IEDs) accounted for an estimated 63% of US fatalities. Furthermore, advancements in protective equipment, combat triage, and treatment have caused an increase in IED casualties surviving with debilitating injuries. Military vehicles have been common targets of IED attacks because of the potential to inflict multiple casualties. Anthropomorphic test devices (ATDs) are mechanical human surrogates designed to transfer loads and display kinematics similar to a human subject. ATDs have been used successfully by the automotive industry for decades to quantify human injury during an impact and assess safety measures. Currently the Hybrid III ATD is used in live-fire military vehicle assessments. However, the Hybrid III was designed for frontal impacts and demonstrated poor biofidelity in vertical loading experiments. To assess military vehicle safety and make informed improvements to vehicle design, a novel Anthropomorphic Test Device (ATD) was developed and optimized for vertical loading. ATDs, commonly referred to as crash dummies, are designed to estimate the risk of injuries to a human during an impact. The main objective of this study was to develop and validate a Finite Element (FE) model of the ATD lower limb.

The master thesis describes communication of PLC and touchscreen with purpose of high voltage control. The general information and framework are included. The thesis describes part of IVEP corporation development. Due to the beginning of a long-term development it is premature to come into conclusions within this master thesis. The first chapter deals with PLC and other components. The second chapter consists of matters about high voltage devices. The following chapter describes the programme part. The fourth and concluding chapter deals with the realization of the communication itself. A brief evaluation with prospects for the future is included in the conclusion.

Master of Science / Department of Computing and Information Sciences / Eugene Vasserman / As medical systems expand to allow for the increase the number of devices, new ways to protect patient safety have be developed. The Integrated Clinical Environment, ICE, standard sets up a set of standards that define what an integrated hospital system is. Within the specification is a direct call for a forensic logger that can be used to review patient and system data. The MDCF is one implementation of the ICE standard, but it lacked a key component the ICE standard requires, a logger. Many loggers exist in industry, with varying rates of success and usefulness. A medically sound logger has to be able to completely retell exactly what happened during an event, including patient, device, and system information, so that the right medical professional can provide the best care. Several loggers have been built for MDCF, but few were practical due to the invasiveness of the service. A universal subscriber, a service that is able to connect to all publishing data streams, logging service was built for the MDCF which has the ability to record all information that passes over the MDCF messaging service. This implementation was then stress tested with varying numbers of devices and amounts of data. A reviewing tool was also built that allows for replay of device data that is similar to the original device UI. Future work will include looking into storing system information such as state changes within MDCF and system health. There is also a push to further integrate the forensic reviewer into the core MDCF UI.

Deep level mining is widely practised throughout South Africa, particularly in the gold sector, where the extraordinary depths of vertical hoisting present an array of challenges. The accurate and secure positioning of a conveyance next to a station has been and continues to be one of the unresolved challenges that have led to many serious injuries and equipment damage. The literature study presented in this dissertation highlights some of the complexities associated with properly docking a conveyance and investigates some current, proposed and similar systems to address the issue. From the study it was found that no satisfactory device existed prompting a systematic design of a conveyance arresting device capable of securing a conveyance in a vertical shaft at any level. Proper definition of the system requirements was obtained and summarised into 16 groups. The system requirements play an important role in the design process by setting the direction but also featuring in concept screening and evaluation. In order to generate concepts a variety of creativity inspiring techniques were employed facilitating a systematic search for a solution. Application of the techniques, Brainstorming, Synectics, TRIZ, 2500 Engineering Principles, Sourcebooks and a Morphological chart resulted in the synthesis of 9 concepts. Screening and evaluation was performed on these concepts and the most suitable concept identified. The proposed concept is a simple system where two sets of beams are extended into the shaft in order to have the conveyance settle onto the supporting shaft steelwork. Once the conveyance came to a rest on the steelwork a second set of beams are extended beneath the steelwork to positively lock the conveyance in position. This required the geometric design of the system to ensure adequate strength to satisfy a factor of safety of ten. Design decisions were made on the section properties of the clamp beam by comparing a solid section and a box section. A supporting frame is used to guide the beams, with consideration given to the most appropriate method of attaching this support frame to the conveyance. The first choice was to have the beams extend from the rear of the conveyance but due to the moments and forces involved the conveyance roof structure could not support this configuration. The support frame was instead affixed directly to the conveyance Transom. In order to support the findings of the conventional calculations performed on the system components the system was subjected to finite element analysis. The results obtained from the simulation corresponded well for the simple components and varied somewhat in the more complex shapes attributed to the assumptions made to ease the conventional calculations. Weight and reliability in a harsh shaft environment was identified as critical design parameters and motivated the use of exotic high strength materials. The high strength of the materials made is possible to design a system with practical dimensions of adequate strength supported by the conventional and modelled calculations. Even though high strength materials were used in the design the overall system weigh is dissatisfying. A potentially successful and practical device was designed but certain factors such as weight, cost, conveyance structure and infrastructure modifications threaten the implementation of the design. This dissertation sets a sound foundation for future development and the continued search for a practical simple solution to this age old challenge. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015