Sanwar A. Sunny

The Convergence of Normalized Vehicular Rolling Friction Coefficient (Crr) by Dynamic High-Speed Imaging and Least Square Optimization Techniques

The paper describes a simple, small scale and low cost yet comprehensive approach to quantifying the Coefficient of Rolling Resistance/Friction (Crr) also known as the Rolling Resistance Coefficient in automobiles. Crr is usually defined as the amount of force required to overcome the hysteresis of the material during tire rotation, where reduced Crr tires can save 1.5–4.5% of automotive fuel consumption. Automotive Standards from the Society of Automotive Engineers use to quantify Crr namely SAE J2452 and SAE J1269 were briefly introduced. Methods of coast down and speed trap tests were conducted under varying body weighted conditions to find the coefficient value, where a high speed camera monitored the motion of the vehicle. The experiment produced different equations of motion which were then solved analytically by numerical analysis techniques to converge on the rolling friction coefficient. A scaled model was used to run dynamic tests and the Reynolds Number (Re) was used to establish a relationship between model and full scale vehicle velocities. Initial guesses in the least square optimization iterations provided coefficient values where drag forces were normalized by assuming constant drag coefficient (CD of 0.40) and then neglecting its contribution during vehicle motion due to the test model size, resulting in a mean Crr of 0.0116. The study results were compared with 3 studies and also against an automotive Crr model. Schmidt 2010 Dynatest Green Road report shares a high 43% error, while the National Academy of Sciences, 2006 and Research Article British Journal of Applied Science & Technology, 3(3): 609-625, 2013 610 Gillespie, 1992 yielded errors of 10.5% and 7.2%. The recent mathematical model of Ehsani 2009 yielded an average Crr value error of 2.3% (with individual test averages of 0.80%). Direct scaling and multiplying abilities were attributed for quantifying the normalized value in the study.

Local level complexities in governance of climate change mitigation practices and adaptation measures in U. S. cities.

While global negotiations regarding climate change between nations are underway around the world, locally scaled policies and measures for climate protection and resilience are drafted and implemented by municipalities across the globe. These political units, with their small contributions to the much larger issue at hand are unable to fully receive adequate gains of their policies for their local stakeholders, as theory states that local level administrators would find it difficult to reduce emissions for the benefit of the global citizenry. In other words, municipalities are concerned with the provision of locallybased public goods and services. For climate policies however, they are locally producing a global public good. On the other hand, local level leaders have an advantage as they control many of the factors related to emissions, such as land use decisions, residential and commercial regulations, transit options and solid waste disposal. This is perhaps fitting due to the nature of the place-based vulnerability where impacts are experienced in the forms of inundation, heat waves, bushfires or rising sea levels. Additionally, due to their structure, it is comparatively easier to implementing such policies successfully than many international policy makers who have struggled with such goals or milestones due to added complications. This essay will explore the rudimentary complexities at the city level and observe the paradox of participation and engagement in sustainable addressing global climate change. Original Research Article British Journal of Environment & Climate Change, 4(1): 5-26, 2014 6