Description:
In competitive cycling, aero-helmets have been used around since 1980 to reduce aerodynamic resistance. Considerable design effort has been made to improve the aerodynamic efficiency of racing bicycle helmets over the years. However, the demand for further improvement has forced helmet manufacturers and designers to introduce new designs progressively. Recently several helmet manufacturers (e.g., LG, Lazer and Giro) have introduced dimples on the outer shell of helmet mimicking the so called 'Golf-ball' dimple effects with a view to further reduce aerodynamic drag of the helmet. However, no independently verifiable research so far has been reported in the public domain about the aerodynamic performance of ribbed bicycle helmets compared to smooth surfaced helmets. Hence, the primary objective of this work was to undertake an experimental study on four smooth aero-helmets including two latest model ribbed aero-helmets to understand their aerodynamic performance and the effect of dimples on helmets. The investigation was undertaken in an wind tunnel environment over a range of wind speeds, pitch and yaw angles. The experimental data indicate no measurable advantage between the smooth and ribbed helmets under varied pitch angles and at zero yaw angle.
Description:
Increasing technological advancements and demand for performance compel the ball manufacturers to introduce new designs. Construction of spherical footballs has been significantly changed over the years since 1970 from 32-panel leather stitched ball to 8-panel synthetic thermally bonded modern football. Despite being most popular game in the world, no data is available on aerodynamic properties of recently FIFA approved balls such as Adidas Cafusa (thermally bonded 32-panel), Nike Maxim (32- panel stitched), Umbro Neo (14-panel stitched, and Mitre Ultimax (26-panel stitched) footballs. Hence, the primary objective of this study was to determine aerodynamic drag of these balls and compare the findings with other balls introduced in late 2000. The aerodynamic forces were measured experimentally for a range of wind speeds in wind tunnel environment and their nondimensional coefficients were determined and compared. Additionally, a field test was also carried out to understand the perception of professional footballers.
Description:
Increasing technological advancements and demand for performance compel the ball manufacturers to introduce new designs. Construction of spherical footballs has been significantly changed over the years since 1970 from 32-panel leather stitched ball to 8-panel synthetic thermally bonded modern football. Despite being most popular game in the world, no data is available on aerodynamic properties of recently FIFA approved balls such as Adidas Cafusa (thermally bonded 32-panel), Nike Maxim (32- panel stitched), Umbro Neo (14-panel stitched, and Mitre Ultimax (26-panel stitched) footballs. Hence, the primary objective of this study was to determine aerodynamic drag of these balls and compare the findings with other balls introduced in late 2000. The aerodynamic forces were measured experimentally for a range of wind speeds in wind tunnel environment and their nondimensional coefficients were determined and compared. Additionally, a field test was also carried out to understand the perception of professional footballers.
Description:
Wireless sensor networks promise to guarantee accurate, fault tolerant and timely detection of events in large scale sensor fields. To achieve this the notion of k-coverage is widely employed in WSNs where significant redundancy is introduced in deployment as an event is expected to be sensed by at least k sensors in the neighborhood. As sensor density increases significantly with k, it is imperative to find the optimal k for the underlying event detection system. In this work, we consider the detection probability, fault tolerance and latency as the Quality of Service (QoS) metrics of an event detection system employing k-coverage and present a probabilistic model to guarantee given QoS support with the minimum degree of coverage taking into account the noise related measurement error, communication interference and sensor fault probability. This work eventually resolves the problem of over or under deployment of sensors, increases scalability and provides a well defined mechanism to tune the degree of coverage according to performance needs.
Description:
Wireless sensor networks promise to guarantee accurate, fault tolerant and timely detection of events in large scale sensor fields. To achieve this the notion of k-coverage is widely employed in WSNs where significant redundancy is introduced in deployment as an event is expected to be sensed by at least k sensors in the neighborhood. As sensor density increases significantly with k, it is imperative to find the optimal k for the underlying event detection system. In this work, we consider the detection probability, fault tolerance and latency as the Quality of Service (QoS) metrics of an event detection system employing k-coverage and present a probabilistic model to guarantee given QoS support with the minimum degree of coverage taking into account the noise related measurement error, communication interference and sensor fault probability. This work eventually resolves the problem of over or under deployment of sensors, increases scalability and provides a well defined mechanism to tune the degree of coverage according to performance needs.
Description:
For cost effective deployment and implementation, mobility is introduced in sensor networks to provide dynamic event coverage. A hybrid network of static and mobile nodes, can yield the same desired accuracy and robustness of a static k-coverage detection model with fewer nodes. Since node movement is a costly operation and the movement strategy has to be decided instantly after event occurrence, it is desirable to have a lightweight distributed node selection and movement scheme. In this work, we propose a game theoretic model to provide dynamic event coverage that achieves the desired detection accuracy with significantly fewer number of nodes while balancing the energy consumption due to mobility and keeping the travelling distance minimum. We address and exploit the spatial clustering nature of events to maximize the overall detection performance over the network lifetime.
Description:
Traditionally, event centric Wireless Sensor Network (WSN) applications treat all events with equal importance, implicitly assuming that all events have same priority. However, in real world applications events may have different level of severity and sensitivity based on their cost of potential damage, occurrence location and frequency. Such applications demand that a detection scheme adopt differentiated treatment of events considering above criteria. Recent works proposed multi-modal sensor nodes for detection of different types of event in a single sensor network and mobile nodes for on-demand attendance of events. When a multi- modal WSN is deployed to monitor events of varied priority, major challenges lies to allocate resources and mobilize mobile nodes in an optimized way to maximize detection performance. We introduce the concept of varied priority and cost of mis-detection of events, and propose a detection scheme for multiple simultaneous events in a hybrid sensor network. Mobile nodes are mobilized through formulation of an optimization problem that maximizes the prioritized accuracy while minimizing detection delay. Theoretical and simulation results demonstrate that our scheme significantly outperforms other scheme that treats all events equally.
Description:
Static analysis of the Windows NTS File System (NTFS) which is the standard and most commonly used file system could provide useful information for digital forensics. However, since the NFTS disk image records every event in the system, forensic tools need to process an enormous amount of information related to user / kernel environment, buffer overflows, trace conditions, network stack and other related subsystems. This leads to imperfect forensic tools that are practical for implementation but not comprehensive and effective. This research discusses the analysis technique to detect data hidden based on the internal structure of the NTFS file system in the boot sector. Further, it attempts to unearth the vulnerabilities of NTFS disk image and weaknesses of the current forensic techniques. The paper argues that a comprehensive tool with improved techniques is warranted for a successful forensic analysis.
Description:
Static analysis of the Windows NTS File System (NTFS) which is the standard and most commonly used file system could provide useful information for digital forensics. However, since the NFTS disk image records every event in the system, forensic tools need to process an enormous amount of information related to user / kernel environment, buffer overflows, trace conditions, network stack and other related subsystems. This leads to imperfect forensic tools that are practical for implementation but not comprehensive and effective. This research discusses the analysis technique to detect data hidden based on the internal structure of the NTFS file system in the boot sector. Further, it attempts to unearth the vulnerabilities of NTFS disk image and weaknesses of the current forensic techniques. The paper argues that a comprehensive tool with improved techniques is warranted for a successful forensic analysis.
Description:
The Internet is a decentralized structure that offers speedy communication, has a global reach and provides anonymity, a characteristic invaluable for committing illegal activities. In parallel with the spread of the Internet, cybercrime has rapidly evolved from a relatively low volume crime to a common high volume crime. A typical example of such a crime is the spreading of spam emails, where the content of the email tries to entice the recipient to click a URL linking to a malicious Web site or downloading a malicious attachment. Analysts attempting to provide intelligence on spam activities quickly find that the volume of spam circulating daily is overwhelming; therefore, any intelligence gathered is representative of only a small sample, not of the global picture. While past studies have looked at automating some of these analyses using topic-based models, i.e. separating email clusters into groups with similar topics, our preliminary research investigates the usefulness of applying authorship-based models for this purpose. In the first phase, we clustered a set of spam emails using an authorship-based clustering algorithm. In the second phase, we analysed those clusters using a set of linguistic, structural and syntactic features. These analyses reveal that emails within each cluster were likely written by the same author, but that it is unlikely we have managed to group together all spam produced by each group. This problem of high purity with low recall, has been faced in past authorship research. While it is also a limitation of our research, the clusters themselves are still useful for the purposes of automating analysis, because they reduce the work needing to be performed. Our second phase revealed useful information on the group that can be utilized in future research for further analysis of such groups, for example, identifying further linkages behind spam campaigns.
Description:
This autoethnography focuses on a study undertaken during the writers 15 month employment in a Muslim girls’ school in the United Arab Emirates. The paper outlines a school improvement project in the Abu Dhabi Emirate and the imposition of an Australian curriculum on the schools involved in this program. The teachers in these schools were exposed to regular professional development sessions as part of an informal teacher education program. While most of the teachers had a degree related to their teaching specialism they lacked any formal teaching qualifications. The professional development the teachers were required to undertake in the schools added to their daily teaching load and did not involve credit towards a degree. School improvement strategies currently in use in Australian state education systems will be discussed in light of their recent implementation in the United Arab Emirates. In discussing the issues that schools faced implementing a new curriculum, teaching approaches, and associated school improvement strategies, it is important that the cultural context of the community and the school be explored with reference to the impact of these proposed changes in many schools across Abu Dhabi. Implementing a new curriculum and encouraging teachers to involve the students in more active learning challenged local teachers’ notions of teaching and of how students learn. An outline of my reasons for undertaking an autoethnography will be provided including the problematic nature of “cultural difference” where a western researcher is working with and observing teachers in a Muslim context. As Rosaldo (1993:202) suggests “Although the notion of “difference” has the advantage of making culture particularly visible to outsiders, it poses a problem because such differences are not absolute. They are relative to the cultural practices of ethnographers and their readers.” On-going discussions related to the western notion of school reform implementation in the Middle East continues to raise issues related to culture and long standing teaching practices that are now being challenged by those who have come from communities and cultures that have very different borders, boundaries and contexts
Description:
The accounting history literature identifies a tendency for accounting in developing countries to be dominated by the style of accounting institutions and practices of western developed nations – particularly the USA and UK. This “importation” hypothesis is investigated and refined through a case study examination of the history of accounting in Malaysia during the formative years of 1957 to 1969. This era commences with the Malay States gaining independence from Britain and closes with the race riots which marked a turning point in the nation’s history. The establishment of the Malaysian Association of Certified Public Accountants (MACPA) in 1958 and the passing of the Companies Act of 1965 and the Accountants Act of 1967 are identified as key events which perpetuated British colonial influence within the new nation. These circumstances add credence to the “importation” hypothesis and support a depiction of accounting and its institutional apparatus as regularising forces with a capacity to transcend political and social change within a nation state.
Description:
In a transform domain distributed video coding scheme, the correlation between the current encoding unit, e.g. block and slice, and the corresponding side-information is modeled using a virtual channel. This correlation model is then used for rate allocation, quantization, and Wyner-Ziv coding. Since the encoder can only have an estimate of the correlation instead of the exact knowledge of the side-information, the decoder will fail to recover the quantized transformed coeffi- cients with a nonzero probability. In this paper, we propose to integrate a scheme at the decoder to recover the undecoded coefficients using the spatial smoothness property of individual video frames. Simulation results demonstrated that, at different decoding failure probabilities, a transformed coeffi- cient recovery scheme can significantly improve the quality of videos in terms of both PSNR and SSIM.
Description:
In a transform domain distributed video coding scheme, the correlation between the current encoding unit, e.g. block and slice, and the corresponding side-information is modeled using a virtual channel. This correlation model is then used for rate allocation, quantization, and Wyner-Ziv coding. Since the encoder can only have an estimate of the correlation instead of the exact knowledge of the side-information, the decoder will fail to recover the quantized transformed coeffi- cients with a nonzero probability. In this paper, we propose to integrate a scheme at the decoder to recover the undecoded coefficients using the spatial smoothness property of individual video frames. Simulation results demonstrated that, at different decoding failure probabilities, a transformed coeffi- cient recovery scheme can significantly improve the quality of videos in terms of both PSNR and SSIM
Description:
In this paper, we have extended the Rice-Golomb code so that it can operate at fractional precision to efficiently exploit the real-valued predictions. Coding at infinitesimal precision allows the residuals to be modeled with the Lap lace distribution. Unlike the Rice-Golomb code, which maps equally probable opposite-signed residuals to different integers, the proposed coding scheme is symmetric in the sense that, at infinitesimal precision, it assigns code words of equal length to equally probable residual intervals. The symmetry of both the Lap lace distribution and the coding scheme facilitates the analysis of the proposed coding scheme to determine the average code-length and the optimal value of the associated coding parameter.
Description:
Abstract— A block-based lossless video coding scheme using the notion of binning has been proposed in [1]. To further improve the compression and reduce the complexity, in this paper we investigate the impact of two sub-optimal motion search algorithms on the performance of this lattice-based scheme. While one of the algorithm tries avoiding motion vectors, the other tries to reduce complexity. Our experimental results have demonstrated that the loss due to sub-optimal motion search outweighs the gain when motion vectors are avoided. However, experimental results have shown that there is negligible performance loss when lowcomplexity sub-optimal three step search is used.
Description:
This paper evaluates applicability and adaptability of ethics and law in Advertising industry to be embedded from an Australian model to an Islamic structure (i.e. UAE, Dubai). Factors such as, government law and policies, ethics, religion, culture, attitudes and values of both sides are essential for such an embedding transaction. The Gulf Cooperation Council (GCC) regulates the main cultural structure aspects in the UAE. Australian competition and consumer commissions (ACCC) is responsible body for law setting and ethical practice monitoring in Australian advertisement industry while Dubai Municipality and economic department, together are responsible to ensure that law and ethical practice application are accomplished properly. Barriers of Islamic countries in advertising industry such as gender, tobacco and liquor stopped them to have further global advertising engagement. Steering media level made by the government has found as the main player to reform believes, culture and religion. Embedding Australian advertisement law and ethical practice into an Islamic structure advertisement seems unusual and requires lots of efforts to be performed. This research is attempting to address the existing research gap in advertising ethics and law practices between Islamic countries compared to non-Muslim societies. The purpose for such an embedding practice would benefits those who are none Muslims and living in Islamic countries.
Description:
Acoustic Emission (AE) has become a powerful tool for Non-Destructive Testing (NDT) and Structural Health Monitoring (SHM) to identify and locate damage in engineering structures. Propagation cracks and other damages emit stress waves which can be detected by suitable sensors mounted on the structures surface. AE is becoming more and more popular for composite structures since it is not only able to monitor a relative large area at a time and without scanning but also because it is able to detect and potentially discriminate all different failure types such as matrix cracking, delamination and fibre breakage. In order to identify the location of AE sources in large plate-like structures it typically requires the use of at least three widely spaced sensors. The distance between these sensors is defined by, for example, expected AE intensity and attenuation of the signals. This paper presents AE monitoring results from a tensile test on a composite plate. The origin of each AE event was located using a novel configuration of the three sensors, which were installed in a closely arranged triangular array with the sensors just 45 mm apart. The algorithm locates AE sources by determining the direction from which the wave approaches the array using the time of arrival and the distance the wave has travelled using the wave mode separation. The test was conducted on a carbon fibre reinforced composite (CFRP) plate with anisotropic lay-up. The technique is particularly suitable for NDT and SHM applications where the close positioning of the sensors allows the array to be installed in one housing to simplify mounting and wiring.