Traffic impact of pedestrianisation in Stellenbosch

The applicability of a pedestrianisation scheme in the historic city center of Stellenbosch, in alleviating the currently experienced transportation related problems, is investigated. These problems negatively affect the general health of a community, decrease tourism attraction and therefore also decrease turnover. Pedestrianisation is, therefore, analysed as being a catalyst for a healthy economy, as well as environment. Various factors are identified as having a key influence in the feasibility of such an undertaking. These include the direct traffic flow patterns, parking utilisation in the area, as well as the operational aspect associated therewith. Each of these are analysed according to their vulnerability to change, given the implementation of such a scheme. Parking demand and resulting vehicle movement patterns are investigated using parking utilisation studies as well as license plate analysis data. When considering the operational aspect of such a scheme, alternative entrance and exit control procedures for delivery vehicles are considered. In terms of the traffic flow impact, a traffic microsimulation analysis was conducted using PTV Vissim. Factors such as queue length, delay time and LOS values are considered before and after implementation of the scheme. Pedestrianisation can be a useful tool in bringing positive change to a city center and can be applied to a wide range of traffic scenarios. Considering this study, it was found that the application of such a scheme is possible due to sufficient alternative parking, a manageable operational aspect as well as a reasonable impact in terms of the traffic flow. It is, therefore recommended that pedestrianisation should be implemented in adding value to central StellenboschPapers Presented at the 2018 37th Southern African Transport Conference 9-12 July 2018 Pretoria, South Africa. Theme "Towards a desired transport future: safe, sufficient and affordable"

Operational concept for connected and autonomous vehicles in an urban environment

Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2031The emergence of Autonomous Vehicles (AVs) can significantly alter how people and goods are transported, as Connected and Autonomous Vehicles (CAVs) offer increased automation as well as improved connectivity between vehicles and roadside infrastructure. Although a future where all vehicles on the road are autonomous, which seems to be farfetched, the rapid development of AV technologies worldwide is a clear indication that local readiness needs to be addressed sooner rather than later. There are many uncertainties regarding how AVs would operate on the road network recognising that few studies have investigated how AVs would operate in an urban environment. This study attempts to provide insight as to how AVs and CAVs perform in such an environment, thus acting as a form of preparation for the future when AVs are eventually implemented. Four levels of autonomous behaviour were evaluated with a microscopic model, developed in PTV VISSIM, to assess the relative improvements that each of these levels provides to the road network’s performance at various penetration rates. The performance of the road network was evaluated by considering various performance indicators, including average network delays, network travel times, network travel speeds, queue lengths, and the average number of stops. Specific focus was also placed on the performance of CAVs and how robust they are to changes in traffic volumes. AVs, and CAVs, were quite effective in improving the network’s performance across all the performance indicators. Additionally, CAVs were quite robust when it came to handling changes in traffic volumes. However, the performance of the AVs were significantly dependent on their penetration rate. The findings in this study provided valuable insight into what the future would look like when AVs are implemented. This research provides a useful, albeit significant, first step in understanding the incremental introduction of CAVs and AVs in South Africa from a traffic engineering perspective

Transformation of in-plane ρ(T)\rho (T) in YBa2Cu3O7−δYBa_{2}Cu_{3}O_{7-\delta} at fixed oxygen content

This paper reveals the origin of variation in the magnitude and temperature dependence of the normal state resistivity frequently observed in different YBCO single crystal or thin film samples with the same $T_{c}$. We investigated temperature dependence of resistivity in $YBa_{2}Cu_{3}O_{7-\delta}$ thin films with 7- $\delta = 6.95$ and 6.90, which were subjected to annealing in argon at 400-420 K ($120-140^{o}C$). Before annealing these films exhibited a non-linear $\rho_{ab}(T)$, with a flattening below 230 K, similar to $\rho_{b}(T)$ and $\rho_{ab}(T)$ observed in untwinned and twinned YBCO crystals, respectively. For all films the annealing causes an increase of resistivity and a transformation of $\rho_{ab}(T)$ from a non-linear dependence towards a more linear one (less flattening). In films with 7- $\delta = 6.90$ the increase of resistivity is also associated with an increase in $T_{c}$. We proposed the model that provides an explanation of these phenomena in terms of thermally activated redistribution of residual O(5) oxygens in the chain-layer of YBCO. Good agreement between the experimental data for $\rho_{ab}(t,T)$, where t is the annealing time, and numerical calculations was obtained.Comment: 8 pages, 9 figures, submitted to PR

Small-city traffic management using unmanned aerial vehicles (uavs)

Dedicated Traffic Management Centres (TMCs) are only operational in three of the largest metropolitan areas in South Africa (in Gauteng, eThekwini and Cape Town). Smaller cities and towns do not have TMCs to assist with traffic management due to the prohibitive cost of these facilities. This research considers the benefits that a small city environment could gain from live traffic management, specifically considering the town of Stellenbosch in the Western Cape as a case study. Stellenbosch experiences heavy congestion during the morning and afternoon peak periods due to significant trip attractions. A framework for the implementation of UAVs to monitor traffic as part of TMC activities was determined for Stellenbosch. A case study includes determination of flight parameters; flight height and speed, as well as the path a could UAV follows to monitor traffic in a 4 km radius around its point of deployment. A framework for the implementation of UAVs to incident response is also created, indicating how UAVs could be used to aid emergency response personnel to better understand and respond to an incident scene. The cost benefit of using UAVs compared to traditional CCTV monitoring for traffic management was evaluated. Additionally, the benefits and limitations of such a system are identified according to findings from the case study. It was determined that using UAVs could provide substantial benefits for traffic monitoring in small city environments.Papers presented virtually at the 39th International Southern African Transport Conference on 05 -07 July 202

Optimized Verlet-like algorithms for molecular dynamics simulations

New explicit velocity- and position-Verlet-like algorithms of the second order are proposed to integrate the equations of motion in many-body systems. The algorithms are derived on the basis of an extended decomposition scheme at the presence of a free parameter. The nonzero value for this parameter is obtained by reducing the influence of truncated terms to a minimum. As a result, the new algorithms appear to be more efficient than the original Verlet versions which correspond to a particular case when the introduced parameter is equal to zero. Like the original versions, the proposed counterparts are symplectic and time reversible, but lead to an improved accuracy in the generated solutions at the same overall computational costs. The advantages of the new algorithms are demonstrated in molecular dynamics simulations of a Lennard-Jones fluid.Comment: 5 pages, 2 figures; submitted to Phys. Rev.

Micromobility : testing suitability through fcd to improve overall mobility

Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2061Micromobility refers to the use of small, lightweight, and often non-motorised vehicles for short trips and last-mile connections that can either by privately owned, or part of a transport offering through a fleet of vehicles owned by a mobility service provider. Micromobility solutions have the potential to significantly reduce congestion and improve the urban environment. This paper aims to investigate how floating car data (FCD) can be used to evaluate the opportunity for micromobility to unlock mobility solutions for both short trips (5 km to 10 km) and long trips (>10 km), to encourage more sustainable urban movement. This paper investigates micromobility options using the town of Stellenbosch as a case study. The potential role of micromobility is investigated by considering typical trip patterns in Stellenbosch, collected through commercial FCD detailing motorised trips. The option of creating linkages between micromobility and infrastructural elements such as vehicle parking areas and “park and ride” facilities to increase the reach of micromobility are also considered. The research revealed a high level of suitability of micromobility for internal trips made within Stellenbosch, and external trips heading into Stellenbosch from surrounds when coupled with infrastructure upgrades (“park and ride”) and ride-share facilities. The paper also demonstrates the benefits of FCD for micromobility planning

Anthocyanin-rich extract decreases indices of lipid peroxidation and DNA damage in vitamin E-depleted rats

Anthocyanins are secondary plant metabolites responsible for the blue, purple, and red color of many plant tissues. The phenolic structure of anthocyanins conveys marked antioxidant activity in model systems via donation of electrons or hydrogen atoms from hydroxyl moieties to free radicals. Dietary intakes of anthocyanins may exceed 200 mg/day, however, little is known about their antioxidant potency in vivo. Consequently, the aim of this study was to establish whether anthocyanins could act as putative antioxidant micronutrients. Rats were maintained on vitamin E-deficient diets for 12 weeks in order to enhance susceptibility to oxidative damage and then repleted with rations containing a highly purified anthocyanin-rich extract at a concentration of 1 g/kg diet. The extract consisted of the 3-glucopyranoside forms of delphinidin, cyanidin, petunidin, peonidin, and malvidin. Consumption of the anthocyanin repleted diet significantly improved (p < 0.01) plasma antioxidant capacity and decreased (p < 0.001) the vitamin E deficiency-enhanced hydroperoxides and 8-Oxo-deoxyguanosine concentrations in liver. These compounds are indices of lipid peroxidation and DNA damage, respectively. Dietary consumption of anthocyanin-rich foods may contribute to overall antioxidant status, particularly in areas of habitually low vitamin E intake.Fundação para Ciência e Tecnologi

Experimental implications of quantum phase fluctuations in layered superconductors

I study the effect of quantum and thermal phase fluctuations on the in-plane and c-axis superfluid stiffness of layered d-wave superconductors. First, I show that quantum phase fluctuations in the superconductor can be damped in the presence of external screening of Coulomb interactions, and suggest an experiment to test the importance of these fluctuations, by placing a metal in close proximity to the superconductor to induce such screening. Second, I show that a combination of quantum phase fluctuations and the linear temperature dependence of the in-plane superfluid stiffness leads to a linear temperature dependence of the c-axis penetration depth, below a temperature scale determined by the magnitude of in-plane dissipation.Comment: 6 pgs, 1 figure, minor changes in comparison with c-axis expt, final published versio