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A collection of research papers and journal articles.

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Defect dependent memory switching in amorphous silicon alloys [a-Si xC1-x:H]
(Electronics Letters, 2002) Shannon, J.M; Gateru, Robert; Gerstner, Ed
It is shown that memory switching in amorphous silicon alloys is affected by ion bombardment. In particular, ion damage lowers the voltage required to form devices and switch them into the on-state. This technique enables optimised non-volatile memory devices to be made with improved switching ratios.
Polarity-dependent forming in ion bombarded amorphous silicon memory devices
(Journal of Applied Physics, 2005) Gateru, Robert; Orwa, J.O; Shannon, J. M.
Polarity-dependent forming in ion bombarded metal±semiconductor±metal (MSM) memory devices of hydrogenated amorphous silicon is reported. It is shown that prior to ion bombardment, current transport in the MSM devices is asymmetric and is controlled by the Schottky barriers at two MS junctions. Upon bombardment, however, there is a bulk component to the current and the I±V characteristics of the devices become symmetric at low bias voltages. The forming voltage in the bombarded devices shows polarity dependence. For positive bias applied on the top contact, we ®nd that devices form at the same electric ®eld independent of the thickness of the amorphous silicon while for negative voltage on the top contact, the electric ®eld needed for forming increases with the thickness. A model involving the difference in energy deposition and heat sinking for the two polarities is proposed
A novel robust and fast Segmentation of the Color Images using Fuzzy Classification C-means
(IEEE, 2010) Felix Musau; Mohamed Lamine Toure; Zou Beiji
This paper brings out a method for segmentation of color images based on fuzzy classification. It proceeds in a first step by a fine segmentation using the algorithm of fuzzy cmeans (FCM). The method then applies a test fusion of fuzzy classes. The result is a coarse segmentation, where each region is the union of elementary regions grown from FCM. The fuzzy C-Means (FCM) clustering is an iterative partitioning method that produces optimal c-partitions, the standard FCM algorithm takes a long time to partition a large data set. The proposed FCM program must read the entire data set into a memory for processing. Our results show that the system performance is robust to different types of images.
Advanced Algorithm for Brain Segmentation using Fuzzy to Localize Cancer and Epilespy Region
(IEEE, 2010) Felix Musau; Zou Beiji; Mohamed Lamine Toure; Aboubacar Damaye Camara
The research which addresses the diseases of the brain in the field of the vision by computer is one of the challenges in recent times in medicine, the engineers and researchers recently launched challenges to carry out innovations of technology pointed in imagery. This paper focuses on a new algorithm for brain segmentation of color images based on fuzzy classification to diagnose accurately the region of cancer and the area of epilepsy. In a first step it proceeds by a fine segmentation using the algorithm of fuzzy cmeans (FCM). It then applies a test fusion of fuzzy classes. The result is a coarse segmentation, where each region is the union of elementary regions grown from FCM. The fuzzy C-Means (FCM) clustering is an iterative partitioning method that produces optimal c-partitions. The standard FCM algorithm takes a long time to partition a large data set. The proposed FCM program must read the entire data set into a memory for processing. Our results show that the system performance is robust to different types of images.
Advanced Algorithm Partitioning of Markov and Color Image Segmentation
(IEEE, 2010) Felix Musau; Zou Beiji; Mohamed Lamine Toure
The color vision systems require a first step of classifying pixels in a given image into a discrete set of color classes. In this paper we introduce a new method of algorithm partitioning, and color image segmentation based on similarities or dissimilarities of the pixels. We consider fuzzy segmentation with markov, and normalized cut method. Experiments show these different processes used an effective solution on natural images, and computational efficiency. Finally, the algorithm has proven our process of experiments on gray scale, color, and texture images show promising segmentation results successful
Group formation with neighbor similarity trust in P2P E-commerce
(Springer Linker, 2011) Felix Musau; Guojun Wang; Muhammad Bashir Abdullahi
The simplicity with which products and prices are compared in e-commerce has introduced an attractive option for many online merchants. The completion of online business transactions with personal information provisioning has always been an act that beckons hesitation. Most online traders are highly conscious of various threats and attacks such as credit card fraud, identity theft, spoofing, hacking, phishing, and other abuses, leading to low trust in online business transactions. Online transactions take place among Peer-to-Peer (P2P) systems at the edge of the Internet. Peer communities are often established dynamically with peers that are unrelated and unknown to each other. In our proposed mechanism, peers form groups in order to ensure trust and security. Each group is established based on interest among peers. In this paper, we show how peers form groups, and select group leaders. A peer can belong to more than one group. Comparing with some existing work, our work reveals that peers can have common neighbors which have a similarity based on their interest. Our simulation results show that the model can deal with the malicious attacks efficiently by comparison with existing models.
A Reliable and Secure Distributed In-Network Data Storage Scheme in Wireless Sensor Networks
(IEEE, 2011) Felix Musau; Guojun Wang; Muhammad Bashir Abdullahi
In a battlefield surveillance scenario, data readings and events emerging from a wireless sensor network deployed that may not be used immediately by or simply impossible to transmit to an authorized user (a Soldier) in real time are stored in the network. Without proper protection for the sensitive data generated in this setting, a compromised storage node (by an enemy soldier) may divulge its stored sensitive data about the monitored environment, and even worse, it may alter the data. In this paper, we integrate an elliptic curve cryptography scheme and an erasure coding scheme to provide reliable and secure distributed in-network data storage for sensor networks. The main idea is to distribute each erasure coded fragment appended with a fingerprint to different storage nodes. The fingerprint is to allow each coded data fragment to be independently verified as a valid and correct subset of a specific data item. So, the scheme achieves localization of data error. The proposed scheme is resilient to collusion attack, pollution attack, and data dropping attack, and guarantees forward and backward data secrecy as well. The security of the proposed scheme relies on the intractability of the elliptic curve discrete logarithm problem. Different from the existing solutions, the uniqueness of our method comes from the use of lightweight encryption scheme, which is well suited for resource constrained wireless sensors.
Similarity Formation of Groups and Key Management in Dynamic Peer to Peer E-commerce.
(IEEE, 2011) Felix Musau; Muhammad Bashir Abdullahi
The ease of shopping and comparing products and prices online has made it an attractive option for many shoppers. When it comes to time to enter personal information or complete a business transaction on the Internet, most people hesitate, and understandably so. They've read about credit card fraud, identity theft, spoofing, hacking, phishing and other abuses. These business transactions take place among peer to peer systems at the edge of the internet. In peer-to-peer environments, a peer needs to interact with unknown entities. In the method proposed, the peers form groups in order to ensure security. Each group is based on interest among the peers and has its own way of operation. The paper gives a clear outline of how peers form groups, select group leaders. Peers can belong to more than one group to a maximum of n groups hence exempt a similarity behavior. This paper also addresses the distribution and management of keys among the peers
Trust and its challenges facing E-Government programs in Kenya
(IEEE, 2011) Felix Musau; Cheruiyot W. Kipruto; Joseph Cosmas Mushi
Kenya’s public sector is at a crossroads today in facing the challenges of institutional change and the impact of new technologies. The public sector can, and will play a much stronger role in implementing all the government plans. The emerging ICT technology can create solid improvement in offering better services to all nations. This can enable the citizens of the countries to access e-services from the governments based on their trust to the systems. In Kenya things have not been as planned as majority of the people don’t trust e-government services. There are many challenges facing its implementation which now remains as a dream, despite the government efforts. The paper raises a lot of concern especially on the trust of the citizens to e-government services being offered and the ICT awareness of the citizens too. The work highlights what the government has done to address the issue. The proposed solutions will help as e-government, and ICT investment has consumed a huge part of the national budget in recent years. The paper addresses how trust influences the change of attitude towards government by employees and the citizens.
Analysis of MS Power Saving Scheme to BS with Finite Buffer in IEEE 802.16e networks
(IEEE, 2011) Felix Musau; Cheruiyot W. Kipruto; Joseph Cosmas Mushi; Guan-Zheng Tan
This paper analyzes effects of power saving of mobile station (MS) to Base Station with finite buffer in IEEE802.16e class type I network. IEEE802.16e standard accept MS to switch to sleep-mode to minimize power when MS processing load is reduced. However, when packets destined to MS appear into BS buffer, they should be stored until end of MS sleep window. Although the sleep-mode designed in effort to conserve environment but it risks loss of packets once BS buffer overloaded with accumulated packets. This paper designs numerical analytic model to measure risk of packet drop. Through asymptotic analysis the effect of packets destined to sleeping MS into BS finite buffer is measured and analysed.
Modeling M-SaaS Delivery Model for Threshold-based Credit Recharging Using Mbanking
(IEEE, 2011) Felix Musau; Joseph Cosmas Mushi; Guan-Zheng Tan; Cheruiyot W. Kipruto
The emerging of cloud computing has brought about new hope for efficient adoption and use of computer based information system. Software as a Service (SaaS) allows online customers to use applications on the Internet on a payas- you-go basis without investing in new infrastructure or software license. However, current SaaS delivery model bring challenge to online customers in community with poor financial services like online bank-transaction or credit cards. This study proposes Mobile-SaaS delivery model to facilitate online charging and credit-recharging mechanisms for SaaS application. The model use mobile-phone monetary services (M-banking) to support online charging, and adopts threshold-based credit recharge technique to support credit recharging.
Principals of trust in internet security and websecure environment
(IEEE, 2011) Felix Musau; Cheruiyot W. Kipruto; Joseph Cosmas Mushi; Juma Modie
Trust and security are key enablers of the information society. Trust is an important aspect of decision making for Internet applications and particularly influences the specification of security policy. It addresses issues on who is authorised to perform actions as well as the techniques needed to manage and implement security in the applications. Trust relates to belief in honesty, truthfulness, competence, and reliability. The significance of incorporating trust in distributed systems is that trust is an enabling surety of good transaction. Its inclusion will enable Internet commerce and seamless, secure agent based applications. This paper investigates trust in relation to security in internet transactions; it specifically deals with different authentication schemes, Encryption, Trust in the websecure environment.
Genetic Algorithm-Enhanced Retrieval Process for Multimedia Data
(International Journal of Advancements in Computing Technology, 2011-04) Felix Musau; Joseph Cosmas Mushi; Guan-Zheng Tan; Cheruiyot W. Kipruto
The explosive growth of digital media content from various domains has given rise to the need for efficient techniques for retrieval of relevant information is getting more and more attention, especially in the large-scale Multimedia Digital Database (MDD) applications. It is for this reason that there has been an increased interest in the query reformulation for use in Multimedia Information Retrieval (MIR) using a combination of various techniques. In this paper, we propose a retrieval method that is formalized as an optimized similarity search process that combines Singular Value Decomposition (SVD), Query Quality Refinement (QQR) using Histogram Equalization and Genetic Algorithm (GA) enhancement. Experimental results show that the approach significantly narrows the search process by retrieving similar images satisfying the needs of the user.
Query quality refinement in singular value decomposition to improve genetic algorithms for multimedia data retrieval
(Springer-Verlag 2011-Multimedia Systems, 2011-04-03) Felix Musau; Joseph Cosmas Mushi; Wilson Cheruiyot; Guan-Zheng Tan
With the development of internet and availability of multimedia data capturing devices, the size of Multimedia Digital Database (MDD) collection is increasing rapidly. The complex data presented by such systems do not have the total ordering property presented by the traditional data handled by Database Management Systems (DBMSs). The quality of the search experience in such systems is also normally a big challenge since users from various domains require efficient data searching, browsing and retrieval tools. This has triggered an important research topic in Multimedia information retrieval concerning efficient and effective image similarity search. Modern search algorithms are fast and effective on a wide range of problems, but on MDD with a large number of parameters and observations, manipulations of large matrices, storage and retrieval of large amounts of information may render an otherwise useful method slow or inoperable. The focus of this work is the application of image enhancement technique, using histogram equalization, to the images retrieved using singular value decomposition (SVD). SVD is a linear algebra technique used for discovering correlations within data. The approach, herein referred to as query quality refinement (QQR) technique, improves the image similarity search result, and when incorporated with genetic algorithms further optimizes the search. These beneficial applications can be extended to other different types of multimedia data in various areas such as the P2P and WiMAX networks.
Performance Analysis of Recharging Scheme of M-SaaS through M-banking
(Journal of Convergence Information Technology (JICT)., 2011-07) Felix Musau; Joseph Cosmas Mushi; Guan-Zheng Tan; Cheruiyot W. Kipruto
Mobile SaaS (M-SaaS) is SaaS delivery model designed to use mobile network infrastructure for reserving and recharging credits of SaaS usage in pay-as-you-go manner for areas with poor financial services. The model integrates M-banking monetary feature into delivery process of SaaS so that potential customers in areas with poor access to financial services, such as online banking and credit cards, participate in SaaS delivery in real-time payment manner. In this paper, we present numerical analysis of M-SaaS recharging process, which together with M-SaaS credit-reservation scheme make M-SaaS model. The analysis shows that utilization and throughput of components involved in the scheme are healthy to avoid interruption of their involvement in other mobile network activities. However, load distribution at equilibrium leads to great imbalance, which needs further study for usefulness of M-SaaS model to revel.
Using Genetic Algorithms to Optimize Web Caching in MultimediaIntegrated e-Learning Content
(International Journal of Digital Content Technology and its Applications, 2011-08) Felix Musau; Joseph C.Mushi; Guan-Zheng Tan; Cheruiyot W. Kipruto
The evolution of e-learning as a new information technology built around the use of internet has originated new possibilities to develop pedagogical methodologies that provide the necessary knowledge and skills in the higher education environment. This has in effect given rise to a large number of learners who desire to access the educational resources provided by the new technology. But for many institutions of higher learning, the users often experiences poor performance when they try to access contents or download e-learning files. The main reasons for such are often performance problems concerning network infrastructure and the fact that many people tend to access the same piece of information repetitively. This paper uses web caching scheme and genetic algorithm optimization to effectively lessen this service bottleneck, diminish the user access latency and reduce the network traffic.
Neighbor Similarity Trust against Sybil Attack in P2P E-Commerce
(IEEE International Conference on Autonomic and Trusted Computing, 2012) Felix Musau; Guojun Wang; Song Guo; Muhammad Bashir Abdullahi
Peer to peer (P2P) e-commerce applications exist at the edge of the Internet with vulnerabilities to passive and active attacks. These attacks have pushed away potential business firms and individuals whose aim is to get the best benefit in e-commerce with minimal losses. The attacks occur during interactions between the trading peers as a transaction takes place. In this paper, we propose how to address Sybil attack, which is a kind of active attack. The peers can have bogus and multiple identity to fake their own ones. Most existing work, which concentrates on social networks and trusted certification, has not been able to prevent Sybil attack peers from participating in transactions. Our work exploits the neighbor similarity trust relationship to address Sybil attack. In this approach, referred to as SybilTrust, duplicated Sybil attack peers can be recognized as the neighbor peers become acquainted and hence more trusted to each other. Security and performance analysis shows Sybil attack can be minimized by our proposed neighbor similarity trust.
Access to Health Care: The Role of a Community Based Health Insurance in Kenya
(Pan African Medical Journal, 2012-06-19) Judy Wanja Mwaura; Sathirakorn Pongpanich
Background: Out-of-pocket payments create financial barriers to health care access. There is an increasing interest in the role of community based health insurance schemes in improving equity and access of the poor to essential health care. The aim of this study was to assess the impact of Jamii Bora Health Insurance on access to health care among the urban poor. Methods: Data was obtained from the household health interview survey in Kibera and Mathare slums, which consisted of 420 respondents, aged 18 and above who were registered as members of Jamii Bora Trust. The members of Jamii Bora Trust were divided into two groups the insured and the non-insured. Results: In total, 17.9% respondents were hospitalized and women (19.6%) were more likely to be admitted than men (14.7%). Those in the poorest quintile had the highest probability of admission (18.1%). Those with secondary school education, large household size, and aged 50 and above also had slightly greater probability of admission (p<0.25). 86% of admissions among the insured respondents were covered JBHI and those in the poorest quintile were more likely to use the JBHI benefit. Results from the logistic regression revealed that the probability of being admitted, whether overall admission or admission covered by the JBHI benefit was determined by the presence of chronic condition (p<0.01). Conclusion: Utilization and take up of the JBHI benefits was high. Overall, JBHI favoured the members in the lower income quintiles who were more likely to use health care services covered by the JBHI scheme.
An Enhanced Service Flow Management Scheme for IEEE 802.16 Broadband Wireless Access Systems
(International Journal of Computer Theory and Engineering, 2012-08) Felix Musau; Juma Modie Mwamafundo; Sang Kipkorir
While the protocols have been proposed to support QoS (quality of service) guarantees for a variety of applications, the WiMax/IEEE 802.16 standard does not specify a mandatory scheduling architecture to fulfill stringent QoS requirement for the different classes of traffic. Only the framework is established in the standard which provides an opportunity for developers to design efficient scheduling mechanism to fulfill stringent QoS requirement for the different classes of traffic. The scheduling scheme requires catering for rigorous QoS guarantee for all types of service flows as specified in the standard, enabling fairness and facilitating the traffic of lower priority. In this paper, we propose a Service Flow Management Scheme for the IEEE 802.16 Broadband Wireless Access systems that can provide QOS support that enhances performance through a scheduler that performs optimally and efficiently.
An Enhanced Service Flow Management Scheme for IEEE 802.16 Broadband Wireless Access Systems
(International Journal of Computer Theory and Engineering, 2012-08) Felix Musau; Sang Kipkorir; Juma Modie Mwamafundo
While the protocols have been proposed to support QoS (quality of service) guarantees for a variety of applications, the WiMax/IEEE 802.16 standard does not specify a mandatory scheduling architecture to fulfill stringent QoS requirement for the different classes of traffic. Only the framework is established in the standard which provides an opportunity for developers to design efficient scheduling mechanism to fulfill stringent QoS requirement for the different classes of traffic. The scheduling scheme requires catering for rigorous QoS guarantee for all types of service flows as specified in the standard, enabling fairness and facilitating the traffic of lower priority. In this paper, we propose a Service Flow Management Scheme for the IEEE 802.16 Broadband Wireless Access systems that can provide QOS support that enhances performance through a scheduler that performs optimally and efficiently.

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