Electromagnetic Vibration Energy Harvesting (EM-VEH) is an attractive alternative to batteries as a power source for wireless sensor nodes that enable intelligence at the edge of the Internet of Things (IoT). Industrial environments in particular offer an abundance of available kinetic energy, in the form of machinery vibrations that can be converted into electrical power through energy harvesting techniques. These ambient vibrations are generally broadband, and multi-modal harvesting configurations can be exploited to improve the mechanical-to-electrical energy conversion. However, the additional challenge of energy conditioning (AC-to-DC conversion) to make the harvested energy useful brings into question what specific type of performance is to be expected in a real industrial application. This paper reports the operation of two practical IoT sensor nodes, continuously powered by the vibrations of a standard industrial compressor, using a multi-modal EM-VEH device, integrated with customised power management. The results show that the device and the power management circuit provide sufficient energy to receive and transmit data at intervals of less than one minute with an overall efficiency of about 30%. Descriptions of the system, test-bench, and the measured outcomes are presented.

Electric Field Energy Harvesting (EFEH) from medium-voltage power lines is an emerging technology to energise the low-cost distributed electronic measurement systems that are needed to monitor vital line parameters for smart grid systems. The challenge with EFEH is to extract energy without requiring a direct connection to the power line conductor. This severely constrains the amount of continuous energy that can be obtained because of the weak capacitive coupling between the power line and the energy harvesting system. This paper addresses this challenge, by using a self-triggered discontinuously operating flyback converter to transform a high voltage DC bus rectified from the weakly coupled AC supply down to useful low voltage levels. The results show that over 20 mW of continuous power can be extracted from a 12.7kV medium-voltage line using this approach. Detailed circuit analysis and matching experimental results are presented to validate the concept.

There is no evidence that mathematical semantics cannot be understood due to blindness, the problem is the current access barrier to mathematical resources. In light of this problem, this survey aims at providing visually impaired persons (VIPs), or people close to them, with an overview of the currently available software tools for approaching mathematical content. These can be categorized into (a) tools for accessing mathematical documents (where VIPs are just consumers of content), and (b) tools that allow VIPs to become the creators of mathematical content and even to execute mathematical operations. We also explain the advantages and disadvantages of several key technologies used to interact with mathematics. Moreover, we discuss the necessity of the most common formats and languages behind these tools. Finally, we outline promising paths for future research and development towards blind-friendly mathematical resources. The authors hope that this survey may encourage researchers to engage with the still unsolved challenges of this topic.

We have developed the prototype of a system that recognizes the denomination of the largest U.S.A. currency notes in circulation in Ecuador, aimed at visually impaired people. It is capable of reproducing audio messages that announce the denomination of a banknote in front of a smartphone camera by processing each frame of its continuous filming. This work takes its theoretical basis from the Digital Image Processing (DIP) techniques and primarily from the image recognition method known as Eigenfaces, which is based on the Principal Component Analysis (PCA) mathematical theory. Tests on two different Nokia smartphones show an accuracy rate of 99.8% and a processing speed of at least 7 frames per second.

One essential requirement for a modern Smart Grid is continuous monitoring of the grid variables. This task is efficiently achieved using self-powered electronic devices deployed throughout the grid network. Within the vicinity of the grid power lines, the high voltages of these lines can provide a source of energy for such loads using capacitive coupling. This is known as Electric-Field Energy Harvesting (EFEH). However, the reported strategies that use this principle have not explored how to maximise their power transfer, which is essential for practical systems since the available energy from EFEH is invariably quite small. In this paper, a novel approach for optimum energy harvesting is proposed using the parasitic capacitance of medium-voltage power line insulators. A follow-on power electronic conversion system is then used to maintain the load conditions that maximise the extracted energy. The system performance has been analysed using theoretical studies and computer simulations to identify the operating conditions that maximise the extracted energy. Results obtained so far suggest that up to 100 mW can be harvested from 22 kV grid feeders, using only the capacitive coupling that exists between the line insulator harvester and the feeder conductor.

The modernization of the current electric power grid into a smart grid requires the integration of advanced instrumentation, automation, and communication technologies to optimize efficiency, safety, and reliability. In traditional power grids, communication and control tasks are concentrated in substations, limiting their coverage to high-power equipment. As distributed energy resources increase in different sections of the grid, power flow becomes bi-directional. This requires monitoring and control at the Transmission and Distribution (T&D) level, which forms the largest portion of the power grid. To achieve efficient energy flow management and enable consumer participation in demand management, the integration of information and communication technologies (ICTs) is essential. Wireless sensor networks (WSNs) have been identified as a suitable solution for communications within the distribution network. An ongoing challenge, however, is the definition of the best candidates to solve this problem, among the currently available wireless technologies. This paper reviews different wireless communication technologies that provide robustness, reliability, speed, scalability, and cost-effectiveness for monitoring distribution lines. An outline of the architecture for smart grid communications, the definition of sensor network requirements for power line environments, and an overview of specific studies focusing on technology comparisons are the main contributions of this paper. The purpose of this review is to delineate current technologies in order to establish potential future research directions within the field.