The ECORA framework: A hybrid architecture for context-oriented pervasive computing

An infrastructure approach to support context-aware pervasive computing is advantageous for rapid prototyping of context-aware distributed applications and beneficial for unifying modelling of context and reasoning in uncertain conditions. This paper presents the ECORA framework for context-aware computing, which is designed with a focus on reasoning about context under uncertainty and addressing issues of heterogeneity, scalability, communication and usability. The framework follows an agent-oriented hybrid approach, combining centralized reasoning services with context-aware, reasoning capable mobile software agents. The use of a centralized reasoning engine provides powerful reasoning capabilities and deploying context-aware mobile agents enables agility and robustness of components in the pervasive system. The design and implementation of the framework at different levels, as well as three case studies, are presented.     

Analysis of optical cavities in the presence of negative refractive index materials

We introduce the ABCD matrix for negative refractive materials (NRM) and investigate the optical properties of (NRM), according to the matrix method. The propagation of a Gaussian beam inside a NRM slab is also investigated. It is demonstrated that for n = −1, the waist of the transmitted Gaussian beam is the same as the waist of incident beam, which leads in the perfect lens. Further the optical resonator in the presence of NRM is studied and the stable condition is introduced. The article is published in the original.     

Design of nonlinear H∞ controllers using describing functions with application to servomechanism

A systematic procedure for design of nonlinear H_∞ controllers for amplitude‐dependent nonlinear plants is presented. The procedure is based on describing function concepts involving sinusoidal input describing function models of the nonlinear plant followed by application of an inverse describing function technique to arrive at nonlinear gains of the H_∞ controller. The procedure is applied to a servomechanism problem to demonstrate the typical results that may be achieved. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

SafeMesh: A wireless mesh network routing protocol for incident area communications

Reliable broadband communication is becoming increasingly important during disaster recovery and emergency response operations. In situations where infrastructure-based communication is not available or has been disrupted, an Incident Area Network needs to be dynamically deployed, i.e. a temporary network that provides communication services for efficient crisis management at an incident site. Wireless Mesh Networks (WMNs) are multi-hop wireless networks with self-healing and self-configuring capabilities. These features, combined with the ability to provide wireless broadband connectivity at a comparably low cost, make WMNs a promising technology for incident management communications. This paper specifically focuses on hybrid WMNs, which allow both mobile client devices as well as dedicated infrastructure nodes to form the network and provide routing and forwarding functionality. Hybrid WMNs are the most generic and most flexible type of mesh networks and are ideally suited to meet the requirements of incident area communications. However, current wireless mesh and ad-hoc routing protocols do not perform well in hybrid WMN, and are not able to establish stable and high throughput communication paths. One of the key reasons for this is their inability to exploit the typical high degree of heterogeneity in hybrid WMNs. SafeMesh, the routing protocol presented in this paper, addresses the limitations of current mesh and ad-hoc routing protocols in the context of hybrid WMNs. SafeMesh is based on the well-known AODV routing protocol, and implements a number of modifications and extensions that significantly improve its performance in hybrid WMNs. This is demonstrated via an extensive set of simulation results. We further show the practicality of the protocol through a prototype implementation and provide performance results obtained from a small-scale testbed deployment.     

An opportunity cost approach for job assignment in a scalablecomputing cluster

A new method is presented for job assignment to and reassignment between machines in a computing cluster. Our method is based on a theoretical framework that has been experimentally tested and shown to be useful in practice. This “opportunity cost” method converts the usage of several heterogeneous resources in a machine to a single homogeneous “cost.” Assignment and reassignment are then performed based on that cost. This is in contrast to traditional, ad hoc methods for job assignment and reassignment. These treated each resource as an independent entity with its own constraints, as there was no clean way to balance one resource against another. Our method has been tested by simulations, as well as real executions, and was found to perform well     

Two-Photon Polymerized Shape Memory Microfibers: A New Mechanical Characterization Method in Liquid

Two-photon polymerization (TPP) is widely used to create 3D micro- and nanoscale scaffolds for biological and mechanobiological studies, which often require the mechanical characterization of the TPP fabricated structures. To satisfy physiological requirements, most of the mechanical characterizations need to be conducted in liquid. However, previous characterizations of TPP fabricated structures are all conducted in air due to the limitation of conventional micro- and nanoscale mechanical testing methods. In this study, a new experimental method is reported for testing the mechanical properties of TPP-printed microfibers in liquid. The experiments show that the mechanical behaviors of the microfibers tested in liquid are significantly different from those tested in air. By controlling the TPP writing parameters, the mechanical properties of the microfibers can be tailored over a wide range to meet a variety of mechanobiology applications. In addition, it is found that, in water, the plasticly deformed microfibers can return to their predeformed shape after tensile strain is released. The shape recovery time is dependent on the size of microfibers. The experimental method represents a significant advancement in mechanical testing of TPP fabricated structures and may help release the full potential of TPP fabricated 3D tissue scaffolds for mechanobiological studies.     

APAE: an IoT intrusion detection system using asymmetric parallel auto-encoder

Neural Computing and Applications - In recent years, the world has dramatically moved toward using the internet of things (IoT), and the IoT has become a hot research field. Among various aspects...