Evans F. Osaisai

Bio: Evans F. Osaisai is an academic researcher. The author has contributed to research in topics: Mechanics & Volume (thermodynamics). The author has an hindex of 1, co-authored 1 publications receiving 38 citations.

Density Current Simulations In Cold Fresh Water And Its Cabbeling phenomenon: A Comparative Analysis With Given Experimental Results

Abstract: The behaviour of warm water discharge at a temperature \(T_{m}\) horizontally into a homogeneous body of cold fresh water at a temperature \(T=0\) was investigated by means of a numerical model through lock-exchange. Water density here was taken to be a quadratic function of temperature. This work as presented here is practical and relevant to many fields of study and also enhances policy making towards the protection of the aquatic ecosystems. Such scenarios are evident in lakes, especially in holomictic lakes and warm discharge from thermoelectric power generating plants. Because the sudden increase in the water temperature after discharge will leads to "thermal shock" killing aquatic life that has become acclimatised to living in a stable temperate environment. The aim of this investigation is to better fathom and as well, gain more insight into such studies. Cabbeling process was key as whenever fluid of different temperature come in contact and as well as the development of Kelvin-Helmholtz instability in the interaction surface. The general behaviours here are dependent of lock volume, density difference and Reynolds number. We noticed that the collapsing velocity of the denser fluid within the first time frame was high, higher than every fluid movement elsewhere. Relations that describes the various regimes of flow were also drawn, and as well as those for the spreading distance \(L_{d c}\) of the density current. However, there are little variations in the scaling laws as compared to the earlier studied cases where density difference was by the means of salt water. But for those where density difference is as a result of temperature, we believe that these results are a good starting point to better fathom and as well, gain more insight into such studies. Lastly, the consideration of barrier position is key, being that the lock volume is also believed to be a factor. Researchers can also gain more knowledge in terms of the dynamics of such flows.

A Numerical Study of the behaviour on Lock Volume Variations in Lock-Exchange Density Current in Cold Fresh Water

Abstract: The behaviour of warm discharge through lock-exchange was investigated numerically, with the assumption that density was taken as a quadratic function of temperature. Simulations were conducted eleven different times varying barrier position. This work as presented here is practical and can also enhance policy making towards the protection of the aquatic ecosystems. Such behaviours are evident in lakes, especially in holomictic lakes and warm discharge from thermoelectric power generating plants. The sudden increase in water temperature after discharge may leads to ”thermal shock” killing aquatic life that has become acclimatised to living in a stable temperate environment. The aim of this investigation is to better fathom and as well, gain more insight into such flows. The results show that regimes of flow is dependent on the size of the lock volume. The general behaviours here are dependent on lock volume, density difference and Reynolds number. Effects of back reflected waves on the propagation speed was not significant for small lock volume simulations. A rapid collapsing behaviour of fluid was noticed for simulations with small lock volume, and the velocity decreases with increase in lock volume in this same phase. Propagation speed is not totally independent of the lock volume. Cabbeling was also key at the point where water masses meet, and as well the development of Kelvin-Helmholtz instabilities. Relations that describes the various regimes of flow are given in Table (1 - 11). Though, there are little variations in the scaling laws as compared to the earlier studied cases where density difference was by the means of salt water. Lastly, it will be interesting if measures can be taken to eliminate the effect of this back reflected waves in other to properly fathom the behaviour in thepropagation of the frontal speed after the slumping phase.

Design of a Presentation Layer for Semantic Net Data Analysis

Abstract: -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------ABSTRACT Semantic Web has become a huge area of research with several directions, this paper is a step towards a dynamic platform design that can perform better services for the Semantic Web. Our platform provides more consistency, easy manipulation and interpretation as well as a presentation environment (User Interface) called the Semantic Net Data Analysis Presentation Environment (SNDAPE). It also suits Big Data analysis in a way that results are valid, consistent and intuitive, because businesses hold these very important since they form the foundation for better decision making. The platform designed provides end-users increased ability to self-manage data from varied resource. It also gives the everyday Semantic Web user; easy ways of extracting knowledge from the web of data. Java is used as the programming language for the implementation of the design through the object-oriented approach to system design.

Propagation Speed of the Frontal Head Through Lock-Exchange Density Current in Cold Fresh Water: Simulations without the Effect of Back-reflected Waves

Abstract: The behaviour of warm water discharged at 4\(^{\circ}\)C through lock-exchange in cold fresh water was investigated numerically, fixing lock volume at the centre of the domain. This investigation as presented here is practical and can also enhance policy making towards the protection of the aquatic ecosystems. Though, the aim of this study is to better fathom and as well, gain more insight into such ows. Our results have shown a speedy movement of the lock volume at the centre of the domain with a leading head at two front on the oor which resulted in a hat shape within the first few time frame. Fluid movement in the second phase is independent of the back reflected waves. We were able to identify two regimes of ow with a stepwise decreasing velocity in the second phase. Our results have shown that velocity with which the current travels with in the second regime is higher within the first time frame as compared to those with the effect of back reflected waves. One major factor that is responsible for decrease in the velocity here is mixing. Previous results have also shown that the front velocities in the collapsing phase are independent of lock volume. But this seem not to be the same here because fluid movement in the first phase (regime) is not totally independent of the lock volume and its position here, where density difference is as a result of temperature. However, our scaling power laws here in the second phase show some variations with previous studies where we have effect of back reflected waves. But results in the collapsing phase here are in strong agreement with those in the first phase of our previous simulations with small lock volume. Generally, the spreading behaviour here is dependent on lock volume, barrier position, density difference and Reynolds number.

Standards for Smart Grid

Abstract: The smart grid is a new advanced electrical network promoted by the government to address environmental sustainability, energy generation, distribution and consumption efficiency issues. As one of the enabling technologies, Advanced Metering Infrastructure refers to systems which measure, collect and analyze energy usage, and interact with advanced devices such as smart meters through various communication media either on request or on pre-defined schedules. This paper focuses on proposing the technical requirements imposed on the communications network for AMI. Then we examine each of the proposed AMI consumer application standards found in open literature based on these requirements. We will discuss the system engineering approach taken by NIST/EPRI to develop standards for smart grid and AMI and highlight outstanding security and interoperability issues concerned for deploying smart grid AMI. We compare the performances of consumer application standards in addressing these open issues. Finally, we conclude and propose our future work. Keywords-smart grid; AMI; IP-based

Service Oriented Computing

Abstract: Service-oriented Architectures (SOA) facilitate the dynamic and seamless integration of services offered by different service providers which in addition can be located in different trust domains. Especially for business integration scenarios, Federated Identity Management emerged as a possibility to propagate identity information as security assertions across company borders in order to secure the interaction between different services. Although this approach guarantees scalability regarding the integration of identity-based services, it exposes a service provider to new security risks. These security risks result from the complex trust relationships within a federation. In a federation the authentication of a user is not necessarily performed within the service provider’s domain, but can be performed in the user’s local domain. Consequently, the service provider has to rely on authentication results received from a federation partner to enforce access control. This implies that the quality of the authentication process is out of control by the service provider and therefore becomes a factor which needs to be considered in the access control step. In order to guarantee a designated level of security, the quality of the authentication process should be part of the access control decision. To ease this process, we propose in this paper a method to rate authentication information by a level of trust which describes the strength of an authentication method. Additionally, in order to support the concept of a two-factor authentication, we also present a mathematical model to calculate the trust level when combining two authentication methods. Quantitative Trust Management (QTM) provides a dynamic interpretation of authorization policies for access control decisions based on upon evolving reputations of the entities involved. QuanTM, a QTM system, selectively combines elements from trust management and reputation management to create a novel method for policy evaluation. Trust management, while effective in managing access with delegated credentials (as in PolicyMaker and KeyNote), needs greater flexibility in handling situations of partial trust. Reputation management provides a means to quantify trust, but lacks delegation and policy enforcement. This paper reports on QuanTM’s design decisions and novel policy evaluation procedure. A representation of quantified trust relationships, the trustdependency graph, and a sample QuanTM application specific to the KeyNote trust management language, are also proposed.

Progress in Intracoronary Optical Coherence Tomography

Abstract: Understanding the etiology and evolution of the vulnerable coronary plaque is important for the early detection, treatment, and prevention of coronary artery disease. Intravascular optical coherence tomography (OCT) enables imaging of the coronary arteries in vivo with sufficient resolution to accurately differentiate arterial pathology, however, the clinical utility of this technology has been limited due to slow image acquisition rates. The development of high-speed Fourier-domain OCT techniques, including optical frequency-domain imaging, enables comprehensive microstructural imaging of long coronary artery segments. Other OCT advancements, including polarization sensitive OCT provides complementary birefringence information that is related to tissue composition. Together with new image processing, acquisition, and display techniques, these advances have enhanced the usability and utility of intracoronary OCT, bringing it closer to becoming a mainstream imaging modality in interventional cardiology.

Smart Grid Wide Area Monitoring, Protection and Control

Abstract: For century, there has been no change in the fundamental structure of the electrical power grid and vehicle networks. Current hierarchical, centrally controlled grid of the electrical grid is not best for growing demand. To address the challenges of the existing power grid, the new concept of smart grid and smarter planet are under research. The smart grid can be considered as a modern electric power grid infrastructure for enhanced efficiency and reliability through automated control, high-power converters, modern communications infrastructure, sensing and metering technologies, and modern energy management techniques based on the optimization of ondemand, energy and network availability. While current power systems are based on a solid information and communication infrastructure, the new smart grid needs a different and much more complex one, as its dimension is much larger and needs utmost performance. This paper addresses critical issues on smart grid technologies primarily in terms of information and communication technology (ICT) issues and opportunities. The main objective of this paper is to provide a contemporary look at the current state of the art in smart grid communications as well as to discuss the still-open research issues in this field. It is expected that this paper will provide a better understanding of the technologies, potential advantages and research challenges of the smart grid and provoke interest among the research community to further explore this promising research area.

Smart Grid Cloud

Abstract: This paper presents a model for smart grid data management based on specific characteristics of cloud computing, such as distributed data management for real-time data gathering, parallel processing for real-time information retrieval, and ubiquitous access. The appliance of the cloud computing model meets the requirements of data and computing intensive smart grid applications. We gathered these requirements by analyzing the set of well-known smart grid use cases, most of which demand flexible collaboration across organizational boundaries of network operators and energy service providers as well as the active participation of the end user. Hence, preserving confidentiality and privacy, whilst processing the massive amounts of smart grid data, is of paramount importance in the design of the proposed Smart Grid Data Cloud.