5,547 research outputs found

    Wind tunnel project for teaching and researching purposes

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    Wind tunnels are test devices used in aerodynamic experiments to understand the effects of air moving through solid objects. Wind tunnels are often used to provide a steady and controlled flow of wind to replace natural winds and to test new models of spacecraft, aircraft and vehicles, and some wind tunnels have enough room to inspect full-size cars. A small wind tunnel system has been acquired and requires re-design and testing. These works follow on the ENG470 work by Mr Ibrahim Noor Izham, who undertook the initial study that analysed the functionality and limitations of the existing wind tunnel. However, the conclusion of the works shows the current wind tunnel does not have the capability to meet the requirements of Murdoch University. Therefore, this project aims to design and construct a new open return wind tunnel system for Murdoch University, which has been designed to achieve 20m / s in the test section with expected low turbulence intensity level. Making it available for Murdoch University research and education purposes, for example, research particular emission from biochar-amended soil, low-speed aerodynamics experiments (ENG 339: Wind and Hydro Power Systems: testing aerofoil and wind turbine models). In order to implement these goals, a very detail design was carried on using theoretical modelling and CFD simulations. Moreover, flow stabilization and control are also performed by using a honeycomb and screens; all of these are optimized to produce low turbulence levels in the test section. Furthermore, the axial fan with a VFD for this wind tunnel project was delivered at the end of March 2019, to assist the subsequent wind tunnel project, an experiment was conducted on 25th May 2019 to study the relationship between wind flow speed generated by the axial fan with different fan speed in RPM. The report has addressed the dimension of the new wind tunnel design by theoretical modelling method. Base on this dimension of the wind tunnel design, an AutoCAD modelling and a CFD simulation is conducted to investigate the turbulence intensity level in the test section. The results show that when the wind tunnel is operated at a wind speed of 20 m / s, the turbulence intensity of the test section is less than 3%. The fan test results show that the maximum wind speed produced by the axial fan is 12.97 m / s, which is much lower than the expected speed of the fan section of 15.405 m / s. The reason is that the vibrations of the fan test structure affect the wind speed measurement of the Pitot tube. In addition, after completing the construction of the entire wind tunnel, the contraction cone will accelerate the flow through the wind tunnel to meet the expected speed

    POWER OF CSAD-BASED TEST ON HERDING BEHAVIOR

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    This study aims to answer the question of whether the cross-sectional absolute deviation (CSAD)-based test is powerful enough to detect herding behavior in financial markets. Using US stocks as the main sample, I investigate the power of the CSAD-based test as a herding detection method, with a focus on two dimensions: the self-consistency of the method and the power of t-tests used in the method. I find that conducting the tests with a large number of stocks over extended time periods is likely to provide consistent conclusions on whether herding behavior exists in the stock market. These findings support the CSAD-based test as a herding detection method. However, with an overall mean of 59.37%, the estimated power of t-tests can be as low as 37.62%, indicating low testing power. Therefore, researchers should be careful when using the CSAD-based test as a herding detection method, especially when R^2s are low

    IS THE BLACK–SCHOLES MODEL GOOD ENOUGH FOR RETAIL INVESTORS IN CHINA?

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    This study answers a simple question for Chinese investors, especially Chinese retail investors: Is the Black–Scholes model good enough for them to make investment decisions? Using the absolute out-of-sample error as a measure of model efficiency, I find that the volume-weighted mean absolute out-of-sample error is 12.03% of the option premium and investors have to tolerate more than 1% absolute error in almost all subsample groups. The significant out-of-sample error indicates that using the Black–Scholes model solely in the decision-making process may have a negative impact on the investments’ performance

    Urban green space management in ancient Chinese capitals: Case studies of Chang’an, Lin’an and Beijing

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    Urban green spaces are crucial for the sustainable development of cities, not only in terms of planning and construction, but also in terms of management frameworks. This exists not only in modern cities, but also in ancient cities, especially in ancient Chinese capitals with high density. However, existing research on green spaces in ancient Chinese cities focuses predominantly on their spatial distribution and morphology as results of planning and construction, while neglecting the underlying and ongoing process of management. This research adopts an integrative case study methodology, selecting three representative high- density ancient Chinese capitals: Chang’an in the Tang Dynasty (618-907), Lin’an in the Southern Song Dynasty (1127-1279), and Beijing in the Qing Dynasty (1644-1911). It systematically examines their green space management, including developmental contexts, institutional frameworks, focal objects, leading forces, and management effectiveness. Through comprehensive analysis and comparison, it is revealed that while ancient Chinese capitals consistently prioritised and institutionalised urban green space management, their distinct historical contexts shaped specific focuses within management practices. Moreover, the nature of administrative agencies and the degree of public participation significantly influenced the long-term efficacy of urban green space management

    Three Essays on Market Efficiency and Corporate Payout Policy

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    Chapters 1 and 2 of this dissertation discuss a special form of regulation, soft intervention, in China. Securities Laws in China are administered by the Chinese Securities Regulatory Commission (CSRC). The CSRC has great flexibility in administering securities laws since the committee represents the will of the state. Under the state-controlled financial system, the CSRC works closely with state-controlled financial firms and suggests, but does not mandate, actions to be taken in the equity market, especially during periods of extreme market stress. These suggestions, or soft interventions, have been used to block trades associated with short positions, significantly reducing short-sales volume and futures trading volume. In Chapters 1 and 2, the impacts of these interventions on put-call parity and the cost of carry model are investigated. There is overwhelming evidence of increased deviations from put-call parity and the cost-of-carry model after soft interventions. Our results are robust after allowing for bid-ask spreads, taxes, transaction costs and Difference-in-Differences comparisons with control securities in the Hong Kong market. Chapter 3 focuses on how changes in dividend policy in 2008 as the financial crisis was unfolding influenced firm risk-adjusted returns in the following years. The sample consists of NYSE- and NASDAQ-traded firms that paid dividends in 2007. These firms are divided into four groups based on their dividend policy in 2008. Evidence shows that firms that decreased or eliminated dividends in 2008 had higher risk-adjusted returns in 2009. The higher risk-adjusted return is consistent with better corporate governance in 2007. This finding suggests that the firms that quickly reacted to the deteriorating economic conditions by cutting dividends and preserving cash were able to better weather the coming financial crisis

    Automated Car Guiding System Using Reinforcement Learning

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    The major objective of this project is to design and implement a car guiding system in a desk-size area, with a remote-controlled toy car. The software, including the calculation, image processing, and movement control, was coded with Python and C++. Q-learning algorithm was selected to be the core of the calculation part, and OpenCV library was used for image processing.The hardware consists of a webcam, a laptop, and a toy car with Bluetooth connection. Some wood boards were also used to build a frame for restraining the area for running the car.The system is able to track the car, detect the obstacles, calculate the optimal path, and send signals to the car in order to control the movement

    Drug prescription support in dental clinics through drug corpus mining

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    The rapid increase in the volume and variety of data poses a challenge to safe drug prescription for the dentist. The increasing number of patients that take multiple drugs further exerts pressure on the dentist to make the right decision at point-of-care. Hence, a robust decision support system will enable dentists to make decisions on drug prescription quickly and accurately. Based on the assumption that similar drug pairs have a higher similarity ratio, this paper suggests an innovative approach to obtain the similarity ratio between the drug that the dentist is going to prescribe and the drug that the patient is currently taking. We conducted experiments to obtain the similarity ratios of both positive and negative drug pairs, by using feature vectors generated from term similarities and word embeddings of biomedical text corpus. This model can be easily adapted and implemented for use in a dental clinic to assist the dentist in deciding if a drug is suitable for prescription, taking into consideration the medical profile of the patients. Experimental evaluation of our model’s association of the similarity ratio between two drugs yielded a superior F score of 89%. Hence, such an approach, when integrated within the clinical work flow, will reduce prescription errors and thereby increase the health outcomes of patients

    Design of New Oscillograph Based on FPGA

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    AbstractOscillograph is one of the necessary measurement instruments in modern electronic design field. A new type of Oscillograph based on FPGA is proposed and designed in this paper. It consists of oscillograph, logic analyzer and signal generator. The resolution of the oscillograph is 8 bit and the maximum value can reach 200Mbps with support of software based on windows operation system. That of the logic analyzer is 100 Msps with 16 channels. The resolution of signal generator is 140Msps with 10-bit
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