Collaborative Fault-Identification & Reconstruction in Multi-Agent Systems

The conventional solutions for fault-detection, identification, and reconstruction (FDIR) require centralized decision-making mechanisms which are typically combinatorial in their nature, necessitating the design of an efficient distributed FDIR mechanism that is suitable for multi-agent applications. To this end, we develop a general framework for efficiently reconstructing a sparse vector being observed over a sensor network via nonlinear measurements. The proposed framework is used to design a distributed multi-agent FDIR algorithm based on a combination of the sequential convex programming (SCP) and the alternating direction method of multipliers (ADMM) optimization approaches. The proposed distributed FDIR algorithm can process a variety of inter-agent measurements (including distances, bearings, relative velocities, and subtended angles between agents) to identify the faulty agents and recover their true states. The effectiveness of the proposed distributed multi-agent FDIR approach is demonstrated by considering a numerical example in which the inter-agent distances are used to identify the faulty agents in a multi-agent configuration, as well as reconstruct their error vectors

Recovery of Localization Errors in Sensor Networks using Inter-Agent Measurements

A practical challenge which arises in the operation of sensor networks is the presence of sensor faults, biases, or adversarial attacks, which can lead to significant errors incurring in the localization of the agents, thereby undermining the security and performance of the network. We consider the problem of identifying and correcting the localization errors using inter-agent measurements, such as the distances or bearings from one agent to another, which can serve as a redundant source of information about the sensor network's configuration. The problem is solved by searching for a block sparse solution to an underdetermined system of equations, where the sparsity is introduced via the fact that the number of localization errors is typically much lesser than the total number of agents. Unlike the existing works, our proposed method does not require the knowledge of the identities of the anchors, i.e., the agents that do not have localization errors. We characterize the necessary and sufficient conditions on the sensor network configuration under which a given number of localization errors can be uniquely identified and corrected using the proposed method. The applicability of our results is demonstrated numerically by processing inter-agent distance measurements using a sequential convex programming (SCP) algorithm to identify the localization errors in a sensor network

A comparative study and analysis of PHES and UGPHES systems.

Master of Science in Power and Energy Systems. University of KwaZulu-Natal, Durban, 2015.Underground Pumped Hydroelectric Energy Storage (UGPHES) is a similar energy storage concept to the conventional Pumped Hydroelectric Energy Storage (PHES) with the major difference being that the lower reservoir is in an underground cavern system. Electricity is stored in the form of gravitational potential energy between a surface reservoir and an underlying subterranean reservoir. In this study, various existing energy storage systems are examined with the UGPHES introduced as an alternative technology for bulk energy storage in South Africa to contribute to the constrained electricity network with environmental and economic benefits. The use of existing infrastructure for the implementation of UGPHES systems is explored, which includes the use of aquifers and abandoned mines. South Africa has large amounts of groundwater as well as transboundary aquifers which may be used for UGPHES systems. A mathematical model is presented which highlights the considerations for the implementation of an aquifer UGPHES system including head and aquifer transmissivity. The use of abandoned mines in South Africa is also explored as it presents an existing underground cavern as well as large amounts of groundwater. Finally, a mathematical model is presented to provide an analysis of the water hammer phenomenon as well as an economic analysis for the use of abandoned mines for UGPHES systems

An improved port knocking authentication framework for mobile cloud computing

The latest developments in mobile cloud computing (MCC) have changed user's priorities for computing. However, the change towards MCC brings new challenges to cloud service providers and administrators. Authentication is one among the challenges categorized in the classification of security issues for MCC. Port knocking authentication method eliminates user's collaboration during the authentication process. Thus, such technique has the potential to be applied on the MCC environment which can ensure reliable communication. However, current port knocking authentication techniques lack of addressing the issue of knock-sequence length. It is challenging to deploy appropriate length sequence for port knocking authentication for the reason that shorter length knock sequence degrades security, whereas, deploying longer length sequence involves performance issues in terms of time and buffer management. This paper proposes a dynamic length port knocking authentication framework which addresses the issue of security degradation and optimizes performance in terms of time up and buffer managment. We employ MikroTik RouterOS for the evaluation of the proposed technique. Analysis of the results shows that dynamic length port knocking authentication technique improves performance in terms of time up to 23% and buffer management up to 28% by reducing the imposed load. Furthermore, by deploying dynamic length (DL) and pool of length (PoL), the proposed method reveals high security, which decreases the probability of hacking knock-sequence near to zero for a number of parallel authentication requests. Hence, dynamic length port knocking authentication technique provides an optimal solution for reliable communication in MCC

THE IMPACT OF ENDORSER'S CREDIBILITY ON CONSUMER RESPONSES: AN EMPIRICAL ENDEAVOR

The purpose of this study is to investigate the influence of endorser's credibility on consumer responses. It also explores the mediating role of attitude towards advertisement (ATA) and moderating role brand awareness (BA). Data were collected from two hundred and sixty-three educated consumers to test the proposed hypotheses. The results suggested that the endorser's credibility (attractiveness, expertise, and trustworthiness) positively impacts ATA and purchase intention (PI). Moreover, ATA mediates between endorser's credibility and PI. It was also found that brand awareness moderates the relationship between ATA and PI. The findings of this study imply that advertisers should carefully consider the endorser's credibility before the selection. In contrast, ignoring these factors could lead to adverse effects on consumer responses. Theoretical implications are also discussed, which are presented in the proceeding sections

Ruptured mycotic reverse saphenous vein graft aneurysm: A late complication of mediastinitis

Reverse saphenous vein graft aneurysm (RSVGA) is a rare complication that occurs after coronary bypass grafting surgery. Mycotic aneurysm of reverse saphenous vein graft is even more rare. We describe the case of a 76-year-old man who underwent coronary artery bypass grafting 10 years back and had mediastinitis four to five months after surgery. He presented with chest pain in July 2017 and was diagnosed as NSTEMI. Angiography showed left main coronary artery disease (90%) with aneurysm of reverse saphenous vein graft to right posterior descending artery(RPDA). Emergent percutaneous coronary intervention (PCI) of the left main artery was performed as the patient suffered ventricular arrhythmia for which cardiopulmonary resuscitation (CPR) was done. After CPR, haematoma appeared on the left side of the sternum subcutaneously. CT scan of the chest was conducted which showed a pseudoaneurysm measuring 35 mm in the mid-segment of reverse saphenous vein graft (RSVG) to the right posterior descending artery (RPDA) with a surrounding mediastinal haematoma communicating with subcutaneous haematoma, so RSVGA to RPDA was coiled. As blood culture grew candida, antifungal medication was started. When the patient\u27s condition stabilised he was discharged

Repair of ascending aortic pseudoaneurysm eroding through the sternum

In reoperation for an ascending aortic pseudoaneurysm eroding through the sternum, a left ventricular vent allows careful unhurried sternal division under deep hypothermic circulatory arrest. We repaired ascending aortic pseudoaneurysms in 2 patients who had undergone aortic valve implantation 6 and 21 months earlier. A minithoracotomy was made in the left 5th intercostal space, and a vent was placed in the left ventricular apex. Repair was accomplished with a bovine pericardial patch reinforced with a Teflon felt strip. Both patients made an uneventful recovery with good functional status at discharge at the 8- and 18-month follow-up

Development of complexity induced frameworks for charged cylindrical polytropes

The main theme of this work is the development of complexity induced generalized frameworks for static cylindrical polytropes. We consider two different definitions of generalized polytopes with charged anisotropic inner fluid distribution. A new methodology based on complexity factor for the generation of consistent sets of differential equations will be presented. We conclude our work by carrying out graphical analysis of developed frameworks.Comment: 21 pages, 6 figure

THE IMPACT OF ENDORSER'S CREDIBILITY ON CONSUMER RESPONSES: AN EMPIRICAL ENDEAVOR

The purpose of this study is to investigate the influence of endorser's credibility on consumer responses. It also explores the mediating role of attitude towards advertisement (ATA) and moderating role brand awareness (BA). Data were collected from two hundred and sixty-three educated consumers to test the proposed hypotheses. The results suggested that the endorser's credibility (attractiveness, expertise, and trustworthiness) positively impacts ATA and purchase intention (PI). Moreover, ATA mediates between endorser's credibility and PI. It was also found that brand awareness moderates the relationship between ATA and PI. The findings of this study imply that advertisers should carefully consider the endorser's credibility before the selection. In contrast, ignoring these factors could lead to adverse effects on consumer responses. Theoretical implications are also discussed, which are presented in the proceeding sections

Impact of FDI on GDP: An Analysis of Global Economy on Production Function

This study examines the effects of Foreign Direct Investment Inflows on Gross Domestic Product on the production function theory by balanced panel data of World Development Indicators from 1992 to 2010 of 59 countries representing the global economy. The empirical analysis on basis of generalized least squares estimator with random effects suggests that there is a significant positive relationship between all the variables of Production Function including Gross Domestic Product and Foreign Direct Investment Inflows. The unit root test confirms the model’s predictive validity and all the three variables significantly explain variation in the Gross Domestic Product, Co-integration test confirms the long-run relationship and Granger causality test finally identifies the presence of unidirectional causality among Gross Domestic Product and Foreign Direct Investment Inflows and Bidirectional causality between the all variables of the original production function. It is recommended for the host nations to emphasize on pro-capital polices to attract and maximize foreign direct investment inflows which will ultimately increase Gross Domestic Product of the host nations