Fuel Consumption Model Generation, Emission Estimation And Life Cycle Cost Analysis

There are a variety of transit bus sizes and types that are suitable for different types of cities, services, and operations. The size of a bus has a direct effect on the operating costs due to fuel consumption. Also, selecting bus size properly is very important for correct functioning and the quality and service level of public transportation. A decision on selecting bus size, fuel type and model year can only be made after considering the demand for each of the service routes on the system, fuel cost, and emission level. It is necessary to provide engineering resources to the local transit service so that they can assign a right size and fuel type of bus to a specific route from the existing bus fleet. Accurate evaluation of fuel consumption is best assessed by comparative testing over relevant drive cycles. In this thesis, a computational model is developed to compare the fuel economy of city transit buses fueled by gasoline and diesel engines considering each bus service route, passenger load variation, and fuel type and bus size. We further explore the potential advantages of each model year and size of the bus for a specific route. Using this automatic calculation process, Transit agencies can develop and design future enhancement of transit services, improve operation efficiency, and environmental benefits of adding additional services with limited funding. This thesis would also be useful to examine the accuracy of projected operating costs and to support decision making on bus purchasing

Miniaturised and reconfigurable planar filters for ultra-wideband applications

An increasing demand for electromagnetic spectrum has resulted from the emergence of feature-rich and faster throughputs wireless applications. This necessitates the developments of dynamic reconfigurable or multifunctional systems to better exploit the existing spectrum. Future wireless devices will be expected to communicate over several bands with various other devices in order to fine tune the services they provide to the user. Each band may require a separate RF transceiver and such modern wireless multi-band multi-mode communication systems call for high performance, highly integrated compact modules. Since the Federal Communications Commission (FCC) released the unlicensed frequency band 3.1-10.6 GHz for ultra-wideband (UWB) commercial communications, the development race for commercialising UWB technology has seen a dramatic increase around the world. The aim of this research is to develop reconfigurable planar microwave filters for ultrawideband applications. The project investigates some key design issues of reconfigurable filters, which are being observed constantly in the latest development and realisation of microwave filters. Both analytical and numerical methods are performed to construct a realistic and functional design. Two different types of frequency reconfigurability are investigated in this thesis: discrete (e.g. PIN diode, Optical switch) and continuous (e.g. varactor diode). Using the equivalent circuits and considering the direct coupled filter structure in most cases, several topologies with attractive features are developed for future communication systems. The proposed works may be broadly categorised into three sections as follows. The first section explores a square ring shape close loop resonator along with an opencircuited stub in the symmetry plane. To realise a reconfigurable frequency states within the same spectrum, an innovative approach is developed for this case. An optical or photoconductive switch, comprised of a silicon die activated using near infrared light is investigated as a substitute of PIN diode and performances are evaluated to compare the feasibilities. In addition, a in-band interference rejection technique via externally coupled Tshape resonator is shown. However, it is observed that both structures achieve significant size reductions by utilising the inner part of the resonators. To improve the filter selectivity, a convenient design approach generating a pair of transmission zeros between both passband edges and a single zero in the stop band for harmonic suppression is discussed in the second section. Moreover, the development of notched rejection bands are studied and several novel methods to create a single and multiple notched bands employing the square ring shape structure are proposed. On inspection, it is found that the notch structure can be implemented without deteriorating the filter performances. The discussions are supplemented with detailed design examples which are accompanied by theoretical, simulated and experimental results in order to illustrate the filter development process and showcase practical filter performance. The third section reveals a novel highly compact planar dual-mode resonator with sharp rejections characteristics for UWB applications. A bandwidth reconfiguring technique is demonstrated by splitting its even-mode resonance. Filter structure with the dual-mode resonator is shown to have a relatively wide tuning range, significantly low insertion loss and a constant selectivity along with frequency variations in comparison to similar published works. Finally, the earlier dual-mode structure are modified to realise a dual wideband behaviour. A detail analysis with comprehensive design procedures is outlined and a solution for controlling the frequency bandwidths independently according to the application interest is provided. In line with the previous section, experimental verification is presented to support and supplement the discussions

Impacts in Fluids: Forces, Scaling Laws and Bouncing Modes in Projectile Impacts on Water Pools and Droplets

Projectile impacts in quiescent water pool are synonymous with intriguing splash phenomena and rich underwater physics. Depending on the material property, geometry and surface conditions of the impacting projectiles coupled with the geometric properties of the water pool (e.g., depth, width etc.), contrasting events like sub-surface cavity formation or bouncing of macro-droplets unfolds over millimetric timescales. In this dissertation, I present four different studies that look at different aspects of impact events with the help of high-speed imaging techniques and implementation of other sensory data acquisition instruments. Firstly, I look at the force of impact associated with projectile water entry and the means of reducing said impact force through consecutive entry of projectiles. I show through a canonical sphere study that by means of consecutive entry of spheres, I can reduce the initial peak impact force felt by the second sphere. I extend this idea of multiple sphere water entry problem with a second study looking at side-by-side entry of spheres at low impact velocities. The close proximity of the two sphere-induced cavities break down the symmetric nature of the otherwise axisymmetric cavity formation mechanism, influencing a wide range of important cavity parameters such as deep-seal pinch-off time, creation of the the surface Worthington jet and underwater trajectories of the impacting spheres. Thirdly, I look at the characteristic times relating to sealing of underwater cavities created through water entry of projectiles, especially the intermediate-speed (30 m/s - 165 m/s projectile impact speed) surface seal cavities. Lastly, I look at deformable spheres impacting macro-water droplet resting on a hydrophobic surface and study a previously unknown droplet bouncing mechanism seen only for the deformable viscoelastic spheres

Comparative physiology of Australian commercial rice cultivars to salinity stress in controlled environment and the field

Salinity intrusion into agricultural lands in rice-producing countries around the world has become a serious threat to food security. Currently, more than 960 million hectares of productive land is adversely affected by salinity and is expected to grow in the future. This problem is exacerbated by the projected increase in world population from the current 7.2 to 9.6 billion by 2050. The cultivated rice (Oryza sativa) tolerates 10 dSm-1. This study used morpho-physiological methods including gas exchange measurement, microelectrode ion flux estimation (MIFE) and agronomic measurements to screen salinity tolerance levels of two Japonica (Koshihikari and Reiziq) rice genotypes and one Indica (Doongara) genotype. In addition, this is the first time that four basic ion fluxes were measured using MIFE in both glasshouse and field conditions to screen rice for salinity tolerance. The effects of salinity stress on photosynthetic activities, ion fluxes and growth parameters of the three rice genotypes under glasshouse conditions and in the field were also examined. Variations in the response of the three cultivars to salinity stress were found, thus providing evidence that morpho-physiological basis of salinity stress tolerance can be applied to improve the salinity stress tolerance of this important crop. This may allow the exploitation of salt affected marginal lands and could positively contribute to global food security

Dynamic interactions between commodity prices and Australian macroeconomic variables

Price swings of commodities affect the economies of commodity exporting nations worldwide and these fluctuations are a major concern for Australian policy makers. Australia is one of the major commodity exporting countries in the global market; therefore, the main focus of this thesis was to shed light on the influence of various fundamental macroeconomic variables on Australian commodity prices. First, emphasis was placed on what magnitude changes in real interest rates and fluctuations of the real exchange rate account for volatility in commodity prices and whether commodity prices tend to show overshooting phenomena (J. Frankel, 1986; J. Frankel, 2006) in reaction to interest rate changes. The possible contribution of global real economic activity to Australian commodities prices was then assessed, which can lead to both higher interest rates and volatile commodity prices (Akram, 2009; Svensson, 2008) within Australia. Similarly, the current slowdown in world economic growth after several years of high growth might clarify the sharp drop in real interest rates and commodity prices. In addition, the present study explored whether Australian resources stock prices had significant predictive ability for the future global commodity price index as suggested by Rossi (2012). Johansen’s (1988, 1991) cointegration technique was utilised to attain the above research objectives and to examine the long-run relationship of the considered variables. This thesis utilised seasonally adjusted monthly time series for real interest rate, real exchange rate, industrial production and resources stock price from January 2000 to December 2015 after considering an appropriate structural break. The study found significant long-run relationships among the variables; therefore, the vector error correction model was applied to judge the short-run dynamic relationship among variables. Then, the forecast ability of all variables was assessed by employing vector error correction Granger causality or block exogeneity tests. Single equation models do not allow the examination of dynamic relations between commodity prices and other macroeconomic variables over different time horizons (Akram, 2009); therefore, the study applied the impulse response technique as well as forecast error variance decomposition to assess the comparative influences of diverse shocks to the variations in key variables of the proposed commodity price model. The research found significant negative relationships between real interest rates and commodity prices. However, the impulse response results did not show any immediate responses of commodity prices because of an impulse in the real interest rate. This showed a significant negative response of commodity prices after six months of the initial shock and the importance of interest rate information to predict the commodity prices in the long run. In two years’ time, approximately one third of the commodity price changes will be explained by the shocks in real interest rate. The shocks from opposite directions showed a significant negative response for real interest rate after having shocks from Australian commodity prices in the medium term. The results of the present study also suggested an immediate fall in Australian commodity prices and thereafter increases at a higher rate significantly in response to the real exchange rate shock, consistent with Frankel’s (1986) overshooting model of commodity prices. This finding raised the question as to whether real exchange rate shocks are a significant factor of Australian macroeconomic instability as commodity export plays an important role in its economy. Results of the present study revealed the response to this query as being in the negative, especially in the long run. The interaction of these two variables from opposite directions showed interesting results. Separate commodity-related drivers of exchange rates results showed that Australian real exchange rate movements were not purely random. Vector error correction-based Granger causality tests indicated a strong support of causality from commodity prices to real exchange rate in the short run. The impulse response results showed the most noteworthy results. The shocks from Australian commodity prices showed immediate significant depreciation in real exchange rates and the index remained depreciated significantly in all horizons, which shows the complete opposite results to many studies (Connolly & Orsmond, 2011; Minifie, Cherastidtham, Mullerworth, & Savage, 2013; Plumb, Kent, & Bishop, 2013; Sheehan & Gregory, 2013). However, this finding is consistent with the theoretical explanation provided by Dumrongrittikul (2012) to explain the puzzle of the Chinese real exchange rate, which is supported by the theoretical explanation of S. Edwards’ (1989) real exchange rate model. The results of the present study also showed that the shock to industrial production had a negative effect on Australian commodity prices and the effect remained significant during all time horizons. It also showed that the commodity price fluctuation had predictive ability of the Australian resources stock prices. After considering these above findings, several policy recommendations for relevant Australian authorities are suggested and limitations are discussed including the pathway for future research

Modified Internal State Variable Models of Plasticity using Nonlocal Integrals in Damage and Gradients in Dislocation Density

To enhance material performance at different length scales, this study strives to develop a reliable analytical and computational tool with the help of internal state variables spanning micro and macro-level behaviors. First, the practical relevance of a nonlocal damage integral added to an internal state variable (BCJ) model is studied to alleviate numerical instabilities associated within the post-bifurcation regime. The characteristic length scale in the nonlocal damage, which is mathematical in nature, can be calibrated using a series of notch tensile tests. Then the same length scale from the notch tests is used in solving the problem of a high-velocity (between 89 and 107 m/s) rigid projectile colliding against a 6061-T6 aluminum-disk. The investigation indicates that incorporating a characteristic length scale to the constitutive model eliminates the pathological mesh-dependency associated with material instabilities. In addition, the numerical calculations agree well with experimental data. Next, an effort is made rather to introduce a physically motivated length scale than to apply a mathematical-one in the deformation analysis. Along this line, a dislocation based plasticity model is developed where an intrinsic length scale is introduced in the forms of spatial gradients of mobile and immobile dislocation densities. The spatial gradients are naturally invoked from balance laws within a consistent kinematic and thermodynamic framework. An analytical solution of the model variables is derived at homogenous steady state using the linear stability and bifurcation analysis. The model qualitatively captures the formation of dislocation cell-structures through material instabilities at the microscopic level. Finally, the model satisfactorily predicts macroscopic mechanical behaviors - e.g., multi-strain rate uniaxial compression, simple shear, and stress relaxation - and validates experimental results

Small-Object Detection in Remote Sensing Images with End-to-End Edge-Enhanced GAN and Object Detector Network

The detection performance of small objects in remote sensing images is not satisfactory compared to large objects, especially in low-resolution and noisy images. A generative adversarial network (GAN)-based model called enhanced super-resolution GAN (ESRGAN) shows remarkable image enhancement performance, but reconstructed images miss high-frequency edge information. Therefore, object detection performance degrades for small objects on recovered noisy and low-resolution remote sensing images. Inspired by the success of edge enhanced GAN (EEGAN) and ESRGAN, we apply a new edge-enhanced super-resolution GAN (EESRGAN) to improve the image quality of remote sensing images and use different detector networks in an end-to-end manner where detector loss is backpropagated into the EESRGAN to improve the detection performance. We propose an architecture with three components: ESRGAN, Edge Enhancement Network (EEN), and Detection network. We use residual-in-residual dense blocks (RRDB) for both the ESRGAN and EEN, and for the detector network, we use the faster region-based convolutional network (FRCNN) (two-stage detector) and single-shot multi-box detector (SSD) (one stage detector). Extensive experiments on a public (car overhead with context) and a self-assembled (oil and gas storage tank) satellite dataset show superior performance of our method compared to the standalone state-of-the-art object detectors.Comment: This paper contains 27 pages and accepted for publication in MDPI remote sensing journal. GitHub Repository: https://github.com/Jakaria08/EESRGAN (Implementation