Resource potentials of composting the organic wastes stream from municipal solid wastes compositions arising in Nigerian cities

The paper presented an assessment of the resource potentials of composting organic waste mate-rials arising from the municipal solid waste stream from cities in Nigeria. Through a review of quantitative data, the composition of municipal solid waste arising within cities in Nigeria was examined in order to identify the potentials for composting organic materials from the waste stream composition. The data showed that the average majority of the waste stream was organic materials which implied high potentials for composting organic waste materials from Nigerian ci-ties. The review also identified further potentials for composting was associated with the large population and the majority of them engaged in agriculture, as a high potential market for com-post manure in Nigeria. There were more potentials derivable from the current policies of im-porting and supplying chemical fertilizer with huge subsidies for domestic agriculture in the country. The need to substitute these policies of chemical fertilizer with the use of compost ma-nure implied high potentials for composting in the country. The paper also identified numerous benefits of composting in general and with particular reference to the Nigerian situation which in-cludes, among others a reduction of the vast quantity of solid waste for final disposal, reducing air pollution and ground water leachate and also employment generation and increased income. Therefore, the paper recommended a deliberate government policy to promote composting of or-ganic solid wastes material and marketing of compost manure to substitute the current policies of importing chemical fertilizer with subsidy for domestic agriculture as a strategy to achieve sus-tainable waste management in Nigeria

Development of a micro-extruder with vibration mode for microencapsulation of human keratinocytes in calcium alginate

Microencapsulation is a promising technique to form microtissues. The existing cell microencapsulation technologies that involved extrusion and vibration are designed with complex systems and required the use of high energy. A micro-extruder with an inclusion of simple vibrator that has the commercial value for creating a 3D cell model has been developed in this work. This system encapsulates human keratinocytes (HaCaT) in calcium alginate and the size of the microcapsules is controllable in the range of 500-800 µm by varying the flow rates of the extruded solution and frequency of the vibrator motor ( I 0-63 Hz). At 0.13 ml/min of flow rate and vibration rate of 26.4 Hz, approximately 40 ± IO pieces of the alginate microcapsules in a size 632.14 ± I 0.35 µm were produced. Approximately I 00 µm suspension of cells at different cells densities of 1.55 x I 05 cells/ml and 1.37 x I 07 cells/ml were encapsulated for investigation of microtissues formation. Fourier transform infrared spectroscopy (FTIR) analysis showed the different functional groups and chemistry contents of the calcium alginate with and without the inclusion of HaCaT cells in comparison to the monolayers of HaCaT cells. From Field Emission Scanning Electron Microscope (FESEM) imaging, calcium alginate microcapsules were characterised by spherical shape and homogenous surface morphology. Via the nuclei staining, the distance between cells was found reduced as the incubation period increased. This indicated that the cells merged into microtissues with good cell-cell adhesions. After 15 days of culture, the cells were still viable as indicated by the fluorescence green expression of calcein­acetoxymethyl. Replating experiment indicated that the cells from the microtissues were able to migrate and has the tendency to form monolayer of cells on the culture flask. The system was successfully developed and applied to encapsulate cells to produce 3D microtissues

Development of a micro-extruder with vibration mode for microencapsulation of human keratinocytes in calcium alginate

Microencapsulation is a promising technique to form microtissues. The existing cell microencapsulation technologies that involved extrusion and vibration are designed with complex systems and required the use of high energy. A micro-extruder with an inclusion of simple vibrator that has the commercial value for creating a 3D cell model has been developed in this work. This system encapsulates human keratinocytes (HaCaT) in calcium alginate and the size of the microcapsules is controllable in the range of 500-800 µm by varying the flow rates of the extruded solution and frequency of the vibrator motor ( I 0-63 Hz). At 0.13 ml/min of flow rate and vibration rate of 26.4 Hz, approximately 40 ± IO pieces of the alginate microcapsules in a size 632.14 ± I 0.35 µm were produced. Approximately I 00 µm suspension of cells at different cells densities of 1.55 x I 05 cells/ml and 1.37 x I 07 cells/ml were encapsulated for investigation of microtissues formation. Fourier transform infrared spectroscopy (FTIR) analysis showed the different functional groups and chemistry contents of the calcium alginate with and without the inclusion of HaCaT cells in comparison to the monolayers of HaCaT cells. From Field Emission Scanning Electron Microscope (FESEM) imaging, calcium alginate microcapsules were characterised by spherical shape and homogenous surface morphology. Via the nuclei staining, the distance between cells was found reduced as the incubation period increased. This indicated that the cells merged into microtissues with good cell-cell adhesions. After 15 days of culture, the cells were still viable as indicated by the fluorescence green expression of calcein­acetoxymethyl. Replating experiment indicated that the cells from the microtissues were able to migrate and has the tendency to form monolayer of cells on the culture flask. The system was successfully developed and applied to encapsulate cells to produce 3D microtissues

JPEG decoder implementation on FPGA using dynamic partial reconfiguration

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia de Electrónica e telecomunicaçõesEsta tese descreve o estudo realizado sobre o tema de Sistemas Computacionais Reconfiguráveis utilizando Field-Programmable Gate Array (FPGA). Sistemas Computacionais Reconfiguráveis é um conceito tão antigo como a computação utilizando circuitos electrónicos. Para explorar os aspetos práticos do conceito, foi implementado um descodificador de imagens codificadas em sistema Baseline JPEGsobre uma FPGA da família Zynq™-7000. Realizado todo o trabalho de desenho, implementação e depuração do descodificador utilizando métodos tradicionais de implementação estática da lógica na FPGA, foi posteriormente realizado o trabalho de adaptação do descodificador desenvolvido para implementação na mesma FPGA utilizando métodos de implementação com reconfiguração parcialdinâmica. Este novo método tem como objetivo principal a realização de um descodificador funcional utilizando apenas uma parte dos recursos lógicos da FPGA quando comparado com a implementação estática do descodificador. A utilização de reconfiguração dinâmica tem como consequência um incremento da complexidade do sistema, originando, numa perspetiva macro, diferenças entre ambos os descodificadores, mas globalmente baseados nos mesmos critérios de desenho e partilhando grande parte dos módulos internos. São ainda descritos os passos para atingir o objetivo, de forma a clarificar o processo de reconfiguração parcial dinâmica para uma aplicação em eventuais novos critérios de projeto e diferentes cenários de aplicação. Esta tese explora ainda o desenvolvimento de sistemas auxiliares que permitem a descodificação direta de ficheiros .jpg e a sua apresentação num monitor VGA.Abstract: This thesis describes a study conducted in Reconfigurable Computing using a Field-Programmable Gate Array (FPGA). Reconfigurable Computing is a concept almost as old as high-speed electronic computing itself. To explore the practical aspects of the concept, a Baseline JPEG image decoder was implemented over a Zynq™-7000 family FPGA. After using traditional methods for the design, implementation and debugging of static decoder logic, the work path was set to adapt the decoder to be implemented on the same FPGA using methods based on Dynamic Partial Reconfiguration. Using this approach the main objective was to develop a working decoder with only a subset of the used resources ofthe FPGA when compared to static implementation of the similar decoder. The dynamic partial reconfiguration brings some additional complexity to the system resulting on two different decoders from a macro perspective view but globally relying on the same design considerations and that share the majority of the internal modules. The steps to achieve the objective are described in order to clarify the dynamic partial reconfiguration process and to eventually open new design possibilities that can be exploited in different application scenarios. The thesis also explores the development of auxiliary systems to enable the ability to decode direct .jpg files and present them on a VGA monitor

An Investigation into the identification, reconstruction, and evidential value of thumbnail cache file fragments in unallocated space

©Cranfield UniversityThis thesis establishes the evidential value of thumbnail cache file fragments identified in unallocated space. A set of criteria to evaluate the evidential value of thumbnail cache artefacts were created by researching the evidential constraints present in Forensic Computing. The criteria were used to evaluate the evidential value of live system thumbnail caches and thumbnail cache file fragments identified in unallocated space. Thumbnail caches can contain visual thumbnails and associated metadata which may be useful to an analyst during an investigation; the information stored in the cache may provide information on the contents of files and any user or system behaviour which interacted with the file. There is a standard definition of the purpose of a thumbnail cache, but not the structure or implementation; this research has shown that this has led to some thumbnail caches storing a variety of other artefacts such as network place names. The growing interest in privacy and security has led to an increase in user’s attempting to remove evidence of their activities; information removed by the user may still be available in unallocated space. This research adapted popular methods for the identification of contiguous files to enable the identification of single cluster sized fragments in Windows 7, Ubuntu, and Kubuntu. Of the four methods tested, none were able to identify each of the classifications with no false positive results; this result led to the creation of a new approach which improved the identification of thumbnail cache file fragments. After the identification phase, further research was conducted into the reassembly of file fragments; this reassembly was based solely on the potential thumbnail cache file fragments and structural and syntactical information. In both the identification and reassembly phases of this research image only file fragments proved the most challenging resulting in a potential area of continued future research. Finally this research compared the evidential value of live system thumbnail caches with identified and reassembled fragments. It was determined that both types of thumbnail cache artefacts can provide unique information which may assist with a digital investigation. ii This research has produced a set of criteria for determining the evidential value of thumbnail cache artefacts; it has also identified the structure and related user and system behaviour of popular operating system thumbnail cache implementations. This research has also adapted contiguous file identification techniques to single fragment identification and has developed an improved method for thumbnail cache file fragment identification. Finally this research has produced a proof of concept software tool for the automated identification and reassembly of thumbnail cache file fragments

System Steganalysis: Implementation Vulnerabilities and Side-Channel Attacks Against Digital Steganography Systems

Steganography is the process of hiding information in plain sight, it is a technology that can be used to hide data and facilitate secret communications. Steganography is commonly seen in the digital domain where the pervasive nature of media content (image, audio, video) provides an ideal avenue for hiding secret information. In recent years, video steganography has shown to be a highly suitable alternative to image and audio steganography due to its potential advantages (capacity, flexibility, popularity). An increased interest towards research in video steganography has led to the development of video stego-systems that are now available to the public. Many of these stego-systems have not yet been subjected to analysis or evaluation, and their capabilities for performing secure, practical, and effective video steganography are unknown. This thesis presents a comprehensive analysis of the state-of-the-art in practical video steganography. Video-based stego-systems are identified and examined using steganalytic techniques (system steganalysis) to determine the security practices of relevant stego-systems. The research in this thesis is conducted through a series of case studies that aim to provide novel insights in the field of steganalysis and its capabilities towards practical video steganography. The results of this work demonstrate the impact of system attacks over the practical state-of-the-art in video steganography. Through this research, it is evident that video-based stego-systems are highly vulnerable and fail to follow many of the well-understood security practices in the field. Consequently, it is possible to confidently detect each stego-system with a high rate of accuracy. As a result of this research, it is clear that current work in practical video steganography demonstrates a failure to address key principles and best practices in the field. Continued efforts to address this will provide safe and secure steganographic technologies

Decentralization of multimedia content in a heterogeneous environment

The aim of this study has been the decentralization of multimedia content in a heterogeneous environment. The environment consisted of the research networks connecting the European Organization for Nuclear Research and the Finnish University and Research Network. The European Organization for Nuclear Research produces multimedia content which can be used as studying material all over the world. The Web University pilot in the European Organization for Nuclear Research has been developing a multimedia content delivery service for years. Delivering the multimedia content requires plenty of capacity from the network infrastructure. Different content of the material can have different demands for the network. In a heterogeneous environment, like the Internet, fulfilling all the demands can be a problem. Several methods exist to improve the situation. Decentralization of the content is one of the most popular solutions. Mirroring and caching are the main methods for decentralization. Recently developed content delivery networks are using both of these techniques to satisfy the demands of the content. The practical application consisted of measurements of the network connection between the multimedia server in the European Organization for Nuclear Research and the Finnish University and Research Network, planning and building a decentralization system for the multimedia content. After the measurements, it became clear that there is n o need for decentralization of the multimedia content for users that are able to utilise the Finnish University and Research Network. There could be double today's usage, and still there would be no problems with the capacity. However, the European Organization for Nuclear Research routes all traffic that comes from outside research networks through a gateway in the USA. This affects every connection that is made from Finland: users are not able to use the international connection offered by the Finnish University and Research Network. For these users I designed and built a simple, modular and portable decentralization system

Plugging in trust and privacy : three systems to improve widely used ecosystems

The era of touch-enabled mobile devices has fundamentally changed our communication habits. Their high usability and unlimited data plans provide the means to communicate any place, any time and lead people to publish more and more (sensitive) information. Moreover, the success of mobile devices also led to the introduction of new functionality that crucially relies on sensitive data (e.g., location-based services). With our today’s mobile devices, the Internet has become the prime source for information (e.g., news) and people need to rely on the correctness of information provided on the Internet. However, most of the involved systems are neither prepared to provide robust privacy guarantees for the users, nor do they provide users with the means to verify and trust in delivered content. This dissertation introduces three novel trust and privacy mechanisms that overcome the current situation by improving widely used ecosystems. With WebTrust we introduce a robust authenticity and integrity framework that provides users with the means to verify both the correctness and authorship of data transmitted via HTTP. X-pire! and X-pire 2.0 offer a digital expiration date for images in social networks to enforce post-publication privacy. AppGuard enables the enforcement of fine-grained privacy policies on third-party applications in Android to protect the users privacy.Heutige Mobilgeräte mit Touchscreen haben unsere Kommunikationsgewohnheiten grundlegend geändert. Ihre intuitive Benutzbarkeit gepaart mit unbegrenztem Internetzugang erlaubt es uns jederzeit und überall zu kommunizieren und führt dazu, dass immer mehr (vertrauliche) Informationen publiziert werden. Des Weiteren hat der Erfolg mobiler Geräte zur Einführung neuer Dienste die auf vertraulichen Daten aufbauen (z.B. positionsabhängige Dienste) beigetragen. Mit den aktuellen Mobilgeräten wurde zudem das Internet die wichtigste Informationsquelle (z.B. für Nachrichten) und die Nutzer müssen sich auf die Korrektheit der von dort bezogenen Daten verlassen. Allerdings bieten die involvierten Systeme weder robuste Datenschutzgarantien, noch die Möglichkeit die Korrektheit bezogener Daten zu verifizieren. Diese Dissertation führt drei neue Mechanismen für das Vertrauen und den Datenschutz ein, die die aktuelle Situation in weit verbreiteten Systemen verbessern. WebTrust, ein robustes Authentizitäts- und Integritätssystem ermöglicht es den Nutzern sowohl die Korrektheit als auch die Autorenschaft von über HTTP übertragenen Daten zu verifizieren. X-pire! und X-pire 2.0 bieten ein digitales Ablaufdatum für Bilder in sozialen Netzwerken um Daten auch nach der Publikation noch vor Zugriff durch Dritte zu schützen. AppGuard ermöglicht das Durchsetzen von feingranularen Datenschutzrichtlinien für Drittanbieteranwendungen in Android um einen angemessen Schutz der Nutzerdaten zu gewährleisten

Plugging in trust and privacy : three systems to improve widely used ecosystems

The era of touch-enabled mobile devices has fundamentally changed our communication habits. Their high usability and unlimited data plans provide the means to communicate any place, any time and lead people to publish more and more (sensitive) information. Moreover, the success of mobile devices also led to the introduction of new functionality that crucially relies on sensitive data (e.g., location-based services). With our today’s mobile devices, the Internet has become the prime source for information (e.g., news) and people need to rely on the correctness of information provided on the Internet. However, most of the involved systems are neither prepared to provide robust privacy guarantees for the users, nor do they provide users with the means to verify and trust in delivered content. This dissertation introduces three novel trust and privacy mechanisms that overcome the current situation by improving widely used ecosystems. With WebTrust we introduce a robust authenticity and integrity framework that provides users with the means to verify both the correctness and authorship of data transmitted via HTTP. X-pire! and X-pire 2.0 offer a digital expiration date for images in social networks to enforce post-publication privacy. AppGuard enables the enforcement of fine-grained privacy policies on third-party applications in Android to protect the users privacy.Heutige Mobilgeräte mit Touchscreen haben unsere Kommunikationsgewohnheiten grundlegend geändert. Ihre intuitive Benutzbarkeit gepaart mit unbegrenztem Internetzugang erlaubt es uns jederzeit und überall zu kommunizieren und führt dazu, dass immer mehr (vertrauliche) Informationen publiziert werden. Des Weiteren hat der Erfolg mobiler Geräte zur Einführung neuer Dienste die auf vertraulichen Daten aufbauen (z.B. positionsabhängige Dienste) beigetragen. Mit den aktuellen Mobilgeräten wurde zudem das Internet die wichtigste Informationsquelle (z.B. für Nachrichten) und die Nutzer müssen sich auf die Korrektheit der von dort bezogenen Daten verlassen. Allerdings bieten die involvierten Systeme weder robuste Datenschutzgarantien, noch die Möglichkeit die Korrektheit bezogener Daten zu verifizieren. Diese Dissertation führt drei neue Mechanismen für das Vertrauen und den Datenschutz ein, die die aktuelle Situation in weit verbreiteten Systemen verbessern. WebTrust, ein robustes Authentizitäts- und Integritätssystem ermöglicht es den Nutzern sowohl die Korrektheit als auch die Autorenschaft von über HTTP übertragenen Daten zu verifizieren. X-pire! und X-pire 2.0 bieten ein digitales Ablaufdatum für Bilder in sozialen Netzwerken um Daten auch nach der Publikation noch vor Zugriff durch Dritte zu schützen. AppGuard ermöglicht das Durchsetzen von feingranularen Datenschutzrichtlinien für Drittanbieteranwendungen in Android um einen angemessen Schutz der Nutzerdaten zu gewährleisten

Digital rights management (DRM) - watermark encoding scheme for JPEG images

The aim of this dissertation is to develop a new algorithm to embed a watermark in JPEG compressed images, using encoding methods. This encompasses the embedding of proprietary information, such as identity and authentication bitstrings, into the compressed material. This watermark encoding scheme involves combining entropy coding with homophonic coding, in order to embed a watermark in a JPEG image. Arithmetic coding was used as the entropy encoder for this scheme. It is often desired to obtain a robust digital watermarking method that does not distort the digital image, even if this implies that the image is slightly expanded in size before final compression. In this dissertation an algorithm that combines homophonic and arithmetic coding for JPEG images was developed and implemented in software. A detailed analysis of this algorithm is given and the compression (in number of bits) obtained when using the newly developed algorithm (homophonic and arithmetic coding). This research shows that homophonic coding can be used to embed a watermark in a JPEG image by using the watermark information for the selection of the homophones. The proposed algorithm can thus be viewed as a ‘key-less’ encryption technique, where an external bitstring is used as a ‘key’ and is embedded intrinsically into the message stream. The algorithm has achieved to create JPEG images with minimal distortion, with Peak Signal to Noise Ratios (PSNR) of above 35dB. The resulting increase in the entropy of the file is within the expected 2 bits per symbol. This research endeavor consequently provides a unique watermarking technique for images compressed using the JPEG standard.Dissertation (MEng)--University of Pretoria, 2008.Electrical, Electronic and Computer Engineeringunrestricte