Service-Relationship Programming Framework for the Social IoT

We argue that for a true realization of innovative programming opportunities for smart spaces, the developers should be equipped with informative tools that assist them in building domain-related applications. Such tools should utilize the services offered by the space's smart things and consider the different relationships that may tie these services opportunistically to build applications. In this paper, we utilize our Inter-thing relationships programming framework to present a distributed programming ecosystem. The framework broadens the restricted set of thing-level relationships of the evolving social IoT paradigm with a set of service-level relationships. Such relationships provide guidance into how services belonging to different things can be combined to build meaningful applications. We also present a uniform way of describing the thing services and the service-level relationships along with new capabilities for the things to dynamically generate their own services, formulate the corresponding programmable interfaces (APIs) and create an ad-hoc network of socially related smart things at runtime. We then present the semantic rules that guide the establishment of IoT applications and finally demonstrate the features of the framework through a proof-of-concept application

From Smart Homes to Smart-ready Homes and Communities

Background: People have various and changing needs as they age and the number of people living with some form of dementia is steadily increasing. Smart homes have a unique potential to provide assisted living but are often designed rigidly with a specific and fixed problem in mind. Objectives: To make smart-ready homes and communities that can be adaptively and easily updated over time to support varying user needs and to deliver the needed assistance, empowerment and living independence. Method: The design and deployment of programmable assistive environment for older adults. Results: The use of platform technology (a special form of what is known today as the Internet of Things, or IoT) has enabled the decoupling of goal setting and application development from sensing and assistive technology deployment and insertion in the assistive environment. Personalising a smart home or changing its applications and its interfaces dynamically as the user needs change was possible and has been demonstrated successfully in one house - the Gator Tech Smart House. Scaling up the platform technology approach to a planned living community is underway at one of UK’s National Health Services (NHS) Healthy New Town projects. Conclusions: There is a great need to integrate technology with living spaces to provide assistance and independent living. But to smarten these spaces for lifelong living, the technology and the smart home applications must be flexible, adaptive and changeable over time. However, people do not just live at home, they live in communities. Looking at the big picture (communities), as well as the small (homes), we consider how to progress beyond smart-ready homes towards smart-ready communities

PV single-phase grid-connected converter : dc-link voltage sensorless prospective

In this paper, a dc-link voltage sensorless control technique is proposed for single-phase two-stage grid-coupled photovoltaic (PV) converters. Matching conventional control techniques, the proposed scheme assigns the function of PV maximum power point tracking to the chopper stage. However, in the inverter stage, conventional techniques employ two control loops: outer dc-link voltage and inner grid current control loops. Diversely, the proposed technique employs only current control loop and mitigates the voltage control loop, thus eliminating the dc-link high-voltage sensor. Hence, system cost and footprint are reduced, and control complexity is minimized. Furthermore, the removal of the dc-link voltage loop proportional-integral controller enhances system stability and improves its dynamic response during sudden environmental changes. The system simulation is carried out, and an experimental rig is implemented to validate the proposed technique effectiveness. In addition, the proposed technique is compared with the conventional one under varying irradiance conditions at different dc-link voltage levels, illustrating the enhanced capabilities of the proposed technique

High performance single-phase single-stage grid-tied PV current source inverter using cascaded harmonic compensators

In this paper, a single-phase single-stage photovoltaic (PV) grid-tied system is investigated. The conventional Pulse Width Modulated (PWM) voltage source inverter (VSI) is replaced by a PWM current source inverter (CSI) for its voltage boosting capabilities, inherent short-circuit proof and higher reliability features. Modeling, design and analysis of the considered CSI are presented altogether with enhanced proposed control loops aided with a modified PWM technique. DC-link even current harmonics are commonly reflected as low-order odd harmonics in the grid resulting in a poor quality grid current. In order to overcome the latter, a high performance Proportional Resonant Controller, applied in the inverter inner grid current loop, is proposed using cascaded resonant control units tuned at low-order frequencies to eliminate injected grid current harmonics. Hence, with a less-bulky smoothing inductor at the CSI DC-side, grid power quality and system efficiency are simultaneously improved. Simulation and experimental results verify the proposed controller effectiveness

Improved performance low-cost incremental conductance PV MPPT technique

Variable-step incremental conductance (Inc.Cond.) technique, for photovoltaic (PV) maximum power point tracking, has merits of good tracking accuracy and fast convergence speed. Yet, it lacks simplicity in its implementation due to the mathematical division computations involved in its algorithm structure. Furthermore, the conventional variable step-size, based on the division of the PV module power change by the PV voltage change, encounters steadystate power oscillations and dynamic problems especially under sudden environmental changes. In this study, an enhancement is introduced to Inc.Cond. algorithm in order to entirely eliminate the division calculations involved in its structure. Hence, algorithm implementation complexity is minimised enabling the utilisation of low-cost microcontrollers to cut down system cost. Moreover, the required real processing time is reduced, thus sampling rate can be improved to fasten system response during sudden changes. Regarding the applied step-size, a modified variable-step size, which depends solely on PV power, is proposed. The latter achieves enhanced transient performance with minimal steady-state power oscillations around the MPP even under partial shading. For proposed technique's validation, simulation work is carried out and an experimental set up is implemented in which ARDUINO Uno board, based on low-cost Atmega328 microcontroller, is employed

IoT-DDL—Device Description Language for the “T” in IoT

We argue that the success of the Internet of Things (IoT) vision will greatly depend on how its main ingredient—the “thing”—is architected and prepared to engage. The IoT’s fragmented and wide-varying nature introduces the need for additional effort to homogenize these things so they may blend together with the surrounding space to create opportunities for powerful and unprecedented IoT applications. We introduce the IoT Device Description Language (IoT-DDL), a machine- and human-readable descriptive language for things, seeking to achieve such integration and homogenization. IoT-DDL explicitly tools things to self-discover and securely share their own capabilities, entities, and services, including the various cloudbased accessories that may be attached to them. We also present the Atlas thing architecture—a lightweight architecture for things that fully exploits IoT-DDL and its specifications. Our architecture provides new OS layers, services, and capabilities we believe a thing must have in order to be prepared to engage in IoT scenarios and applications. The architecture and IoT-DDL enable things to generate their offered services and self-formulate APIs for such services, on the fly, at power-on or whenever a thing description changes. The architecture takes advantage of widely used device management, micro-services, security, and communication standards and protocols. We present details of IoT-DDL and corresponding parts of the thing architecture. We demonstrate some features of IoT-DDL and the architecture through proof-of-concept implementations. Finally, we present a benchmarking study to measure and assess time performance and energy consumption characteristics of our architecture and IoT-DDL on real hardware platforms

Persuasive Health:Back to the Future

With individual behaviour and lifestyle determining 30-50% of people’s health, research and supportive technology for affecting behaviour alteration remain urgently needed. Most existing persuasive systems are designed to persuade a user to change a finite set of behaviours to achieve a specific goal. However, if the user’s situation or goal changes, such systems cannot adapt to the changes. A much more robust type of persuasive systems is needed today to enable adequate health navigation and to empower people to face and change their own realities in terms of a large variety of health behaviours and lifestyles. In this paper, we provide a perspective on the impressive body of work contributed over the past 15 years, to better look into the future of persuasive health and to the opportunities a broader theoretical framework and practical methodologies may bring about. We present a taxonomy that attempts to explain the contributions in this field including health behaviour theory, cybernetic action behaviour models, social cognitive theory, and control theory. We identify potentially promising approaches to advance persuasive health’s efficacy in empowering individuals to improve their own health outcomes

Reliability, Availability, Dependability and Performability: A User-centered View

Reliability and availability have long been considered twin system properties that could be enhanced by distribution. Paradoxically, the traditional definitions of these properties do not recognize the positive impact of recovery---as distinct from simple repair and restart---on reliability, nor the negative effect of recovery, and of internetworking of clients and servers, on availability. As a result of employing the standard definitions, reliability would tend to be underestimated, and availability overestimated. We offer revised definitions of these two critical metrics, which we call service reliability and service availability, that improve the match between their formal expression, and intuitive meaning. A fortuitous advantage of our approach is that the product of our two metrics yields a highly meaningful figure of merit for the overall dependability of a system. But techniques that enhance system dependability exact a performance cost, so we conclude with a cohesive definiti..