Vehicular ad hoc networks (VANETs) are an extreme case of mobile ad hoc networks (MANETs). High speed and frequent network topology changes are the main characteristics of vehicular networks. These characteristics lead to special issues and challenges in the network design, especially at the medium access control (MAC) layer. Due to high speed of nodes and their frequent disconnections, it is difficult to design a MAC scheme in VANETs that satisfies the quality-of-service requirements in all networking scenarios. In this thesis, we provide a comprehensive evaluation of the mobility impact on the IEEE 802.11p MAC performance. The study evaluates basic performance metrics such as packet delivery ratio, throughput, and delay, as well as the impact of mobility factors. The study also presents a relation between the mobility factors and the respective medium access behavior. Moreover, a new unfairness problem according to node relative speed is identified for both broadcast and unicast scenarios. To achieve better performance, we propose two dynamic contention window mechanisms to alleviate network performance degradation due to high mobility. Extensive simulation results show the significant impact of mobility on the IEEE 802.11p MAC performance, an identification of a new unfairness problem in the vehicle-to-vehicle (V2V) communications, and the effectiveness of the proposed MAC schemes.

The transportation crisis in Atlanta has attained epic proportions. Inconveniences and hardships created by too many automobiles and not enough alternatives for movement, have reached untenable levels. Getting at what lies beneath the asphalt, interrogating what drives the paving of America, along with the seemingly unstoppable space, energy, and money consumption that the current mode of mobility entails will perhaps allow for future decision-making that includes a more nuanced reading of the landscape. In an effort to understand these forces, I interrogate the creation, trajectories, and current positioning of three major Atlanta transportation projects: the Metropolitan Atlanta Rapid Transit Authority (MARTA), the bus and rail system that has been the backbone of metropolitan Atlanta’s public transportation system for the past 30 years; the Georgia Regional Transportation Authority (GRTA), which is the super-agency created in 1999 in an effort to address the air quality issues in the region; and the Beltline, an enormously popular current proposal to build a 22-mile loop of greenspace, transit, and other amenities around an inner loop of the city built on existing rail beds. This investigation engages a wide literature on race, space, and place; attendance at various meetings and relevant symposia; archival data; and in-depth interviews with 20 area transportation experts and interested parties. As race and regionalism are so central to understanding power and procedure in metro Atlanta, particular attention is given to racial and spatial practices. This research reveals the contest over issue framing between car-centered growth promoters, environmental (or green) actors, and social justice, or equity proponents and how the outcomes of this triumvirate’s competition results in regional transportation policies and procedures. The examination of the three instances; MARTA, GRTA, and the Beltline, give us an excellent window into the making of mobility in the region. INDEX WORDS: Transportation, Atlanta, Race and Regionalism, Mobility, GRTA, Beltline, MARTA.

This thesis is a qualitative interview study with the purpose of describing how women living with physical disabilities view their experiences and expectations connected to sexuality. It also aims to highlight how the surrounding society treats these women regarding their sexuality. Through semi-structured interviews; six single- and one group interview, the data was collected during a two month long Minor Field Study in Dar es Salaam, Tanzania. An interpreter, with a degree in Kiswahili/English translation at the University of Dar es Salaam was translating the interviews from Kiswahili to English. The results of this study show that the women living with physical disabilities view themselves as capable and strong sexual beings even if they at the same time face many challenges. The challenges they face are both on an individual and a structural level. These challenges are often connected to the men they have long or short relationships with and are closely linked to both how the men and the society view physical disability and the female sex. This thesis shows that when it comes to sexuality the women all hope for a radical change towards a society that can meet their needs better and the women’s stories clearly highlight the importance of seeing the society itself as the disabling mechanism instead of seeing themselves as disabled individuals.

Background and aim: Persons sustaining different types of brain injury may experience difficulties with advanced mobility. Both persons with traumatic brain injury (TBI) and persons born with very low birth weight (VLBW) have similar brain abnormalities, such as reduced white matter and connectivity, and may thus experience similar mobility problems. However, few studies have assessed advanced motor abilities, and none have compared mobility functions in adult TBI and VLBW populations. Our aim was to investigate high level mobility functions in adults with TBI and VLBW adults compared to matched controls, and to compare high-level mobility in TBI and VLBW adults. Methods: Participants consisted of 22 subjects (mean age 22.9 ± 2.0 yrs) with chronic traumatic brain injury, and 35 subjects (mean age 22.5 ± 0.7 yrs) born preterm with birth weight (below 1500 grams). Two TBI participants were not able to complete all test items due to pain. The VLBW group included three subjects with cerebral palsy (CP). Each group was matched with its own control group, consisting of 24 subjects each from the same geographical area matched by age and sex. Mean age in the control group was 23.3 ± 1.8 yrs for TBI and 22.8 ± 0.5 yrs for VLBW. Advanced mobility functions were assessed by the High-level Mobility Assessment Tool (HiMAT), which consists of 13 timed mobility tasks, with a maximum total HiMAT score of 54. Results: Mean total HiMAT score in the TBI group was 47.0 ± 7.7 compared to 50.3 ± 3.9 for the controls (U=193, p=0.116). Three of 13 mobility tasks differed significantly from the control group: ‘walking’, ‘walk over obstacle’ and ‘bound non-affected leg’. When the two subjects who reported pain were excluded from the analysis, mean total HiMAT score was 48.9 ± 4.9 (U=193, p=0.264), with ‘walking’ and ‘walk over obstacle’ remaining significantly different from the control group. In the TBI group, nine (40.9%) participants performed at or below the 5th percentile compared to 6 (25%) of the TBI controls. Mean total HiMAT score in the VLBW group was 45.1 ± 7.8 compared to 49.9 ± 3.5 in its control group (U = 256, p=0.011). Five of the 13 mobility task scores were significantly different from the control group: ‘walking backwards’, ‘running’, ‘hop affected leg’, ‘bound affected leg’, and ‘bound non-affected leg’. When the three subjects with CP were excluded, mean total HiMAT score was 46.8 ± 5.5 in the VLBW group (U=256, p=0.033) and three mobility task scores remained significantly different from the controls: ‘walking backwards’, ‘hop affected leg’ and ‘bound non-affected leg’. In the VLBW group, 17 (48.6%) participants performed at or below the 5th percentile compared to 4 (16.7%) of the VLBW controls. When directly compared to the VLBW group, the TBI group had (OR 0.733, CI 0.249 – 2.154) lower risk for performing at or below the 5th percentile, although not significant. Conclusions: Compared to controls, adults with TBI had reduced high-level mobility in specific tasks. Adults born with VLBW had reduced overall high level mobility. Furthermore, the HiMAT seems to be a valuable tool for assessing high-level mobility in VLBW populations, and should be formally tested for further use. Keywords: High-level mobility, high-level mobility assessment tool, traumatic brain injury, very low birth weight

Introduction: Driver perceptions may be a more important determinant of behaviour than one’s actual driving abilities. While there is evidence to support these associations, prior studies have relied on self-reports of driving behaviour. Purpose: The primary purposes of this study were to extend previous research by examining driver perceptions in relation to measures of actual driving behaviour and to compare the perceptions and behaviour of sole versus couple drivers. Methods: A convenience sample of 61 older drivers (aged 67 to 92, 59% women) were recruited as either sole drivers (only driver in the household, n=39) or couples (both currently driving and sharing a vehicle, n=22). Two in-vehicle devices (one with a GPS unit) were installed in participant vehicles for one week. Participants completed trip logs, out-of-home activity diaries, questions on usual driving habits and ratings of situational driving frequency and avoidance. Perceptions were assessed using the Driving Comfort Scales (DCS Day and Night) and Perceived Driving Abilities (PDA) Scales. Couples were also asked to rate their comfort level in their partner’s driving using modified DCSs. Tools were administered at one of two home visits (during which vehicle devices were installed and removed) and an interview conducted at the end to ascertain whether the week’s driving was typical. Results: Driving comfort scores were significantly related to multiple indicators of actual driving behaviour, including: radius from home (DCS-D, p<.05; DCS-N, p<.01), total distance overall (DCS-N, p<.001) and at night (DCS-D, p<.05; DCS-N, p<.01). Perceived abilities, meanwhile, were related to distance driven (p<.01). Although sole drivers were significantly older, they drove more often, longer distances and for greater duration than couple drivers. Overall, men had higher DCS scores and, in couples, were more likely to rate themselves higher than their spouses. Partners’ comfort levels in their spouses’ driving were related to their spouses’ self-reported situational avoidance and amount of night driving over the study week. When couples drove together, traditional roles were evident (i.e., the husband often preferred to drive and the wife let him). Multivariate analyses showed that the square-root of distance (km) was most influenced by household status, location of residence, perceived abilities, and gender (R2 = .57), while the log of the average radius was influenced by location of residence and perceived comfort in night driving (R2 = .33). Conclusions: This was the first study to examine older drivers’ perceptions in relation to actual driving behaviour and to compare the perceptions and behaviour of sole versus couple drivers. Study results supported prior associations (with self-reported driving) and extended our knowledge base by demonstrating that perceptions (both personal and those of others) are important to actual driving behaviour. The current findings also provide new insight into the importance of examining location of residence and household status.

Vehicular ad hoc networks (VANETs) are an extreme case of mobile ad hoc networks (MANETs). High speed and frequent network topology changes are the main characteristics of vehicular networks. These characteristics lead to special issues and challenges in the network design, especially at the medium access control (MAC) layer. Due to high speed of nodes and their frequent disconnections, it is difficult to design a MAC scheme in VANETs that satisfies the quality-of-service requirements in all networking scenarios. In this thesis, we provide a comprehensive evaluation of the mobility impact on the IEEE 802.11p MAC performance. The study evaluates basic performance metrics such as packet delivery ratio, throughput, and delay, as well as the impact of mobility factors. The study also presents a relation between the mobility factors and the respective medium access behavior. Moreover, a new unfairness problem according to node relative speed is identified for both broadcast and unicast scenarios. To achieve better performance, we propose two dynamic contention window mechanisms to alleviate network performance degradation due to high mobility. Extensive simulation results show the significant impact of mobility on the IEEE 802.11p MAC performance, an identification of a new unfairness problem in the vehicle-to-vehicle (V2V) communications, and the effectiveness of the proposed MAC schemes.

Mobility of the horse to initiate motion from the standing position is examined in this thesis. In particular, the thesis focuses on the study of the mobility of a horse with fixed hooves to the ground, and on how its musculoskeletal system is used to free the legs from restraints. Possible leg patterns to initiate motions are investigated. The breaking forces generated at front and hind hooves during static-pulling and dynamic jerking are evaluated. Design of the restraint system that uses ropes to immobilize certain joints in order to prevent the horse from generating these forces is the main objective of this thesis. Such a system could be applied as an alternative to rather massive mechanical devices, the main purpose of which is to block the breaking forces (which are quite large when fully developed).<p> Analysis of the mobility of the horse is based on the mechanics of a skeletal linkage system driven by muscle forces. Only major muscles involved in fighting the restraints are included in the analysis. The force generation capability of a muscle is determined by physiological cross sectional area (PCSA) of the muscle. Possible leg patterns are predicted with the kinematics analysis considering range of motion at each joint in the legs. Corresponding breaking forces generated in each pattern is evaluated with the kinetics analysis. Relationship between the characteristic parameter of the pattern and the breaking force at hoof are established. <p>The horse's computer model is used to justify the analytical result. Fighting mechanisms of the horse are simulated in the dynamic simulation software package. Patterns and the breaking forces developed by the horse model simulation agree well with the analytical results. To the authors best knowledge, this is the first time a computer model is used in analyzing the method of restraining an animal. <p>The mobility of the animal with hoof restraints and methods to remove mobility were further confirmed with a preliminary animal restraint test conducted on a sheep. The sheep was chosen because the leg patterns to initiate motion on a horse are similar to that of sheep, but the sheep is more convenient to handle. The experiment showed that the mobility of the sheep could be removed completely by restraining its hooves, lower legs, and head with easily attached ropes.

Current-voltage (I-V) characteristics of organic molecular glasses and solution processable materials embedded between two electrodes were studied to find materials possessing high charge-carrier mobilities and to design organic memory devices. The comparison studies between TOF, FET and SCLC measurements confirm the validity of using analyses of I-V characteristics to determine the mobility of organic semiconductors. Hexaazatrinaphthylene derivatives tri-substituted by electron withdrawing groups were characterized as potential electron transporting molecular glasses. The presence of two isomers has important implications for film morphology and effective mobility. The statistical isomer mixture of hexaazatrinaphthylene derivatized with pentafluoro-phenylmethyl ester is able to form amorphous films, and electron mobilities with the range of 10 E cm2/Vs are observed in their I-V characteristics. Single-layer organic memory devices consisting of a polymer layer embedded between an Al electrode and ITO modified with Ag nanodots (Ag-NDs) prepared by a solution-based surface assembly demonstrated a potential capability as nonvolatile organic memory device with high ON/OFF switching ratios of 104. This level of performance could be achieved by modifying the ITO electrodes with some Ag-NDs that act as trapping sites, reducing the current in the OFF state. Based upon the observed electrical characteristics, the currents of the low-resistance state can be attributed to a tunneling through low-resistance pathways of metal particles originating from the metal top electrode in the organic layer and that the high-resistance state is controlled by charge trapping by the metal particles including Ag-NDs. In an alternative approach, complex films of AgNO3: hexaazatrinaphthylene derivatives were studied as the active layers for all-solution processed and air-stable organic memory devices. Rewritable memory effects were observed in the devices comprised of a thin polymer dielectric layer deposited on the bottom electrode, the complex film, and a conducting polymer film as the top electrode. The electrical characteristics indicate that the accumulation of Ag+ ions at the interface of the complex film and the top electrode may contribute to the switching effect.

In this thesis we synthesize discotic liquid crystal materials. After demonstrating the molecular structures by 1H-NMR of Acid-6, we measure the properties of this material. We use discotic liquid crystal Acid-6 and measure its¡¦ properties. It shows the properties of Acid-6 which is having the ability of absorbing visible light. By UV-Vis spectrum, we can realize the absorption band is located at 400 nm and confirm that it is able to be a photo-sensitized dye. Besides, the property of discotic liquid crystal is the self-assembly ability, the molecular can assemble into hexagonal columnar structure by themselves, which enable discotic liquid crystal to have better mobility. The DSSCs have good power conversion efficiency with using discotic liquid crystals Acid-6. We can measure its¡¦ mobility to know the component with which the most appropriate.

Discotic liquid crystals (DLCs), which consist of disk-like molecules, have recently attracted considerable attention for their interesting electronic properties. One of the most significant of DLCs is their high charge carrier mobility in their columnar structure. Recently the number of researches have been increasing on applications such as organic light-emitting diodes (OLED), photovoltaic devices (OPV) and organic field-effect transistors (OFET). The purpose of the study is to investigate the mobility of different alignment of DLCs. The material used in the present study is HDBP-8. We will show that the stack of DLCs depended on temperature strongly. We will also discuss charge transport properties of homeotropic alignment. Carrier transport has been investigated in the hexagonal columnar (Colh) mesophase of HDBP-8 using time-of-flight (TOF) technique. The carrier mobilities are up to the order of 10-3 cm2V-1s-1 for both positive and negative charges with weak dependence on the electric fields.