Technologies

16 pages, 5342 KB

Open AccessArticle

Effective Current Pre-Amplifiers for Visible Light Communication (VLC) Receivers

by Simon-Ilias Poulis, Georgios Papatheodorou, Christoforos Papaioannou, Yiorgos Sfikas, Marina E. Plissiti, Aristides Efthymiou, John Liaperdos and Yiorgos Tsiatouhas

Technologies 2022, 10(1), 36; https://doi.org/10.3390/technologies10010036 - 21 Feb 2022

Cited by 2 | Viewed by 3634

Abstract

Visible light communication (VLC) is an upcoming wireless communication technology. In a VLC system, signal integrity under low illumination intensity and high transmission frequencies are of great importance. Towards this direction, the performance of the analog front end (AFE) sub-system either at the [...] Read more.

Visible light communication (VLC) is an upcoming wireless communication technology. In a VLC system, signal integrity under low illumination intensity and high transmission frequencies are of great importance. Towards this direction, the performance of the analog front end (AFE) sub-system either at the side of the transmitter or the receiver is crucial. However, little research on the AFE of the receiver is reported in the open literature. Aiming to enhance signal integrity, three pre-amplification topologies for the VLC receiver AFE are presented and compared in this paper. All three use bipolar transistors (BJT): the first consists of a single BJT, the second of a double BJT in cascade connection, and the third of a double BJT in Darlington-like connection. In order to validate the performance characteristics of the three topologies, simulation results are provided with respect to the light illumination intensity, the data transmission frequency and the power consumption. According to these simulations, the third topology is characterized by higher data transmission frequencies, lower illuminance intensity and lower power consumption per MHz of operation. Full article

(This article belongs to the Special Issue MOCAST 2021)

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24 pages, 1663 KB

Open AccessEditor’s ChoiceArticle

Sovereign Digital Consent through Privacy Impact Quantification and Dynamic Consent

by Arno Appenzeller, Marina Hornung, Thomas Kadow, Erik Krempel and Jürgen Beyerer

Technologies 2022, 10(1), 35; https://doi.org/10.3390/technologies10010035 - 21 Feb 2022

Cited by 7 | Viewed by 4124

Abstract

Digitization is becoming more and more important in the medical sector. Through electronic health records and the growing amount of digital data of patients available, big data research finds an increasing amount of use cases. The rising amount of data and the imposing [...] Read more.

Digitization is becoming more and more important in the medical sector. Through electronic health records and the growing amount of digital data of patients available, big data research finds an increasing amount of use cases. The rising amount of data and the imposing privacy risks can be overwhelming for patients, so they can have the feeling of being out of control of their data. Several previous studies on digital consent have tried to solve this problem and empower the patient. However, there are no complete solution for the arising questions yet. This paper presents the concept of Sovereign Digital Consent by the combination of a consent privacy impact quantification and a technology for proactive sovereign consent. The privacy impact quantification supports the patient to comprehend the potential risk when sharing the data and considers the personal preferences regarding acceptance for a research project. The proactive dynamic consent implementation provides an implementation for fine granular digital consent, using medical data categorization terminology. This gives patients the ability to control their consent decisions dynamically and is research friendly through the automatic enforcement of the patients’ consent decision. Both technologies are evaluated and implemented in a prototypical application. With the combination of those technologies, a promising step towards patient empowerment through Sovereign Digital Consent can be made. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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2 pages, 188 KB

Open AccessEditorial

Editorial for the Special Issue “Advances in Multiscale and Multifield Solid Material Interfaces”

by Raffaella Rizzoni, Frédéric Lebon, Serge Dumont and Michele Serpilli

Technologies 2022, 10(1), 34; https://doi.org/10.3390/technologies10010034 - 18 Feb 2022

Viewed by 2303

Abstract

Interfaces play an essential role in determining the mechanical properties and the structural integrity of a wide variety of technological materials [...] Full article

(This article belongs to the Special Issue Advances in Multiscale and Multifield Solid Material Interfaces)

15 pages, 7368 KB

Open AccessEditor’s ChoiceArticle

Self-Supervised Human Activity Representation for Embodied Cognition Assessment

by Mohammad Zaki Zadeh, Ashwin Ramesh Babu, Ashish Jaiswal and Fillia Makedon

Technologies 2022, 10(1), 33; https://doi.org/10.3390/technologies10010033 - 17 Feb 2022

Cited by 6 | Viewed by 3682

Abstract

Physical activities, according to the embodied cognition theory, are an important manifestation of cognitive functions. As a result, in this paper, the Activate Test of Embodied Cognition (ATEC) system is proposed to assess various cognitive measures. It consists of physical exercises with different [...] Read more.

Physical activities, according to the embodied cognition theory, are an important manifestation of cognitive functions. As a result, in this paper, the Activate Test of Embodied Cognition (ATEC) system is proposed to assess various cognitive measures. It consists of physical exercises with different variations and difficulty levels designed to provide assessment of executive and motor functions. This work focuses on obtaining human activity representation from recorded videos of ATEC tasks in order to automatically assess embodied cognition performance. A self-supervised approach is employed in this work that can exploit a small set of annotated data to obtain an effective human activity representation. The performance of different self-supervised approaches along with a supervised method are investigated for automated cognitive assessment of children performing ATEC tasks. The results show that the supervised learning approach performance decreases as the training set becomes smaller, whereas the self-supervised methods maintain their performance by taking advantage of unlabeled data. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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27 pages, 3415 KB

Open AccessEditor’s ChoiceReview

Mechanical Properties of Sustainable Metal Matrix Composites: A Review on the Role of Green Reinforcements and Processing Methods

by Sankaranarayanan Seetharaman, Jayalakshmi Subramanian, Ramachandra Arvind Singh, Wai Leong Eugene Wong, Mui Ling Sharon Nai and Manoj Gupta

Technologies 2022, 10(1), 32; https://doi.org/10.3390/technologies10010032 - 16 Feb 2022

Cited by 44 | Viewed by 9808

Abstract

Growing concerns like depleting mineral resources, increased materials wastage, and structural light-weighting requirements due to emission control regulations drive the development of sustainable metal matrix composites. Al and Mg based alloys with relatively lower melting temperatures qualify for recycling applications and hence are [...] Read more.

Growing concerns like depleting mineral resources, increased materials wastage, and structural light-weighting requirements due to emission control regulations drive the development of sustainable metal matrix composites. Al and Mg based alloys with relatively lower melting temperatures qualify for recycling applications and hence are considered as the matrix material for developing sustainable composites. The recent trend also explores various industrial by-products and agricultural wastes as green reinforcements, and this article presents insights on the properties of Al and Mg based sustainable metal matrix composites with special emphasis on green reinforcements and processing methods. Full article

(This article belongs to the Special Issue Commemorative Issue in Honor of Prof. Dr. Manoj Gupta on the Occasion of 60th Birthday)

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26 pages, 3215 KB

Open AccessArticle

Insights on the Effect and Experience of a Diet-Tracking Application for Older Adults in a Diet Trial

by Laura M. van der Lubbe, Michel C. A. Klein, Marjolein Visser, Hanneke A. H. Wijnhoven and Ilse Reinders

Technologies 2022, 10(1), 31; https://doi.org/10.3390/technologies10010031 - 16 Feb 2022

Viewed by 3538

Abstract

With an ageing population, healthy ageing becomes more important. Healthy nutrition is part of this process and can be supported in many ways. The PROMISS trial studies the effect of increasing protein intake in older adults on their physical functioning. Within this trial, [...] Read more.

With an ageing population, healthy ageing becomes more important. Healthy nutrition is part of this process and can be supported in many ways. The PROMISS trial studies the effect of increasing protein intake in older adults on their physical functioning. Within this trial, a sub-study was performed, researching the added effect of using a diet-tracking app enhanced with persuasive and (optional) gamification techniques. The goal was to see how older adult participants received such technology within their diet program. There were 48 participants included in this sub-study, of which 36 completed the study period of 6 months. Our results on adherence and user evaluation show that a dedicated app used within the PROMISS trial is a feasible way to engage older adults in diet tracking. On average, participants used the app 83% of the days, during a period of on average 133 days. User-friendliness was evaluated with an average score of 4.86 (out of 7), and experienced effectiveness was evaluated with an average score of 4.57 (out of 7). However, no effect of the technology on protein intake was found. The added gamification elements did not have a different effect compared with the version without those elements. However, some participants did like the added gamification elements, and it can thus be nice to add them as additional features for participants that like them. This article also studies whether personal characteristics correlate with any of the other results. Although some significant results were found, this does not give a clear view on which types of participants like or benefit from this technology. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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23 pages, 7851 KB

Open AccessArticle

Adapt or Perish? Exploring the Effectiveness of Adaptive DoF Control Interaction Methods for Assistive Robot Arms

by Kirill Kronhardt, Stephan Rübner, Max Pascher, Felix Ferdinand Goldau, Udo Frese and Jens Gerken

Technologies 2022, 10(1), 30; https://doi.org/10.3390/technologies10010030 - 14 Feb 2022

Cited by 8 | Viewed by 4060

Abstract

Robot arms are one of many assistive technologies used by people with motor impairments. Assistive robot arms can allow people to perform activities of daily living (ADL) involving grasping and manipulating objects in their environment without the assistance of caregivers. Suitable input devices [...] Read more.

Robot arms are one of many assistive technologies used by people with motor impairments. Assistive robot arms can allow people to perform activities of daily living (ADL) involving grasping and manipulating objects in their environment without the assistance of caregivers. Suitable input devices (e.g., joysticks) mostly have two Degrees of Freedom (DoF), while most assistive robot arms have six or more. This results in time-consuming and cognitively demanding mode switches to change the mapping of DoFs to control the robot. One option to decrease the difficulty of controlling a high-DoF assistive robot arm using a low-DoF input device is to assign different combinations of movement-DoFs to the device’s input DoFs depending on the current situation (adaptive control). To explore this method of control, we designed two adaptive control methods for a realistic virtual 3D environment. We evaluated our methods against a commonly used non-adaptive control method that requires the user to switch controls manually. This was conducted in a simulated remote study that used Virtual Reality and involved 39 non-disabled participants. Our results show that the number of mode switches necessary to complete a simple pick-and-place task decreases significantly when using an adaptive control type. In contrast, the task completion time and workload stay the same. A thematic analysis of qualitative feedback of our participants suggests that a longer period of training could further improve the performance of adaptive control methods. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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12 pages, 8569 KB

Open AccessArticle

On the In-Die Conditions and Process Parameter Settings in Indirect Squeeze Casting

by Anders E. W. Jarfors, Andong Du, Jie Zhou, Jinchuan Zheng and Gegang Yu

Technologies 2022, 10(1), 29; https://doi.org/10.3390/technologies10010029 - 11 Feb 2022

Viewed by 2762

Abstract

The current study investigated the relationship between the process settings and in-die conditions to understand the transitions between the different filling stages and the final pressure settings in indirect squeeze casting. A pressure sensor was placed in the die cavity to indirectly measure [...] Read more.

The current study investigated the relationship between the process settings and in-die conditions to understand the transitions between the different filling stages and the final pressure settings in indirect squeeze casting. A pressure sensor was placed in the die cavity to indirectly measure the evolution of pressure over time and monitor the filling process to study the in-die conditions. The pressure–time profile was analysed, and the maximum pressure and acceleration of the pressure were investigated empirically. The main conclusion of this paper is that the use of increasing intensification pressures is positive for the casting soundness. However, it must be stressed that there is a strong effect from the intensification pressure on the acceleration that has a far more reaching influence than the actual speed setting. A direct practical outcome is that a high intensification pressure has a more substantial effect than the second stage fill speed. This translates directly to a possibility of reducing the second stage fill speed to stabilise the fill front. Furthermore, this also pinpoints the need for improvements in hydraulics system designs to decouple the intensification pressure from the filling piston motion control. Full article

(This article belongs to the Section Manufacturing Technology)

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18 pages, 1305 KB

Open AccessEditor’s ChoiceArticle

Visible Light Communications for Internet of Things: Prospects and Approaches, Challenges, Solutions and Future Directions

by Stephen S. Oyewobi, Karim Djouani and Anish Matthew Kurien

Technologies 2022, 10(1), 28; https://doi.org/10.3390/technologies10010028 - 5 Feb 2022

Cited by 82 | Viewed by 9857

Abstract

Visible light communications (VLC) is an emerging and promising concept that is capable of solving the major challenges of 5G and Internet of Things (IoT) communication systems. Moreover, due to the usage of light-emitting diodes (LEDs) in almost every aspect of our daily [...] Read more.

Visible light communications (VLC) is an emerging and promising concept that is capable of solving the major challenges of 5G and Internet of Things (IoT) communication systems. Moreover, due to the usage of light-emitting diodes (LEDs) in almost every aspect of our daily life VLC is providing massive connectivity for various types of massive IoT communications ranging from machine-to-machine, vehicle-to-infrastructure, infrastructure-to-vehicle, chip-to-chip as well as device-to-device. In this paper, we undertake a comprehensive review of the prospects of implementing VLC for IoT. Moreover, we investigate existing and proposed approaches implemented in the application of VLC for IoT. Additionally, we look at the challenges faced in applying VLC for IoT and offer solutions where applicable. Then, we identify future research directions in the implementation of VLC for IoT. Full article

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16 pages, 2472 KB

Open AccessEditor’s ChoiceArticle

Performance Analysis of 2D and 3D Bufferless NoCs Using Markov Chain Models

by Konstantinos Tatas

Technologies 2022, 10(1), 27; https://doi.org/10.3390/technologies10010027 - 2 Feb 2022

Cited by 1 | Viewed by 2972

Abstract

Performance analysis and design space exploration of bufferless Networks-on-Chip is done mainly through time-consuming cycle-accurate simulation, due to the chaotic nature of packet deflections, which have thus far prevented the development of an accurate analytical model. In order to raise the level of [...] Read more.

Performance analysis and design space exploration of bufferless Networks-on-Chip is done mainly through time-consuming cycle-accurate simulation, due to the chaotic nature of packet deflections, which have thus far prevented the development of an accurate analytical model. In order to raise the level of abstraction as well as capture the inherently probabilistic behavior of deflection routing, this paper presents a methodology for employing Markov chain models in the analysis of the behavior of bufferless Networks-on-Chip. A formal way of describing a bufferless NoC topology as a set of discrete-time Markov chains is presented. It is demonstrated that by combining this description with the network average distance, it is possible to obtain the expectation of the number of hops between any pair of nodes in the network as a function of the flit deflection probability. Comparisons between the proposed model and cycle-accurate simulation demonstrate the accuracy achieved by the model, with negligible computational cost. The useful range of the proposed model is quantified, demonstrating that it has an error of less than 10% for a significant proportion (between 33 and 75%) of the injection rate range below saturation. Finally, a simple equation for comparing mesh topologies with a “back-of-the-envelope” calculation is introduced. Full article

(This article belongs to the Special Issue MOCAST 2021)

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18 pages, 5237 KB

Open AccessEditor’s ChoiceArticle

Reliable IoT-Based Monitoring and Control of Hydroponic Systems

by Konstantinos Tatas, Ahmad Al-Zoubi, Nicholas Christofides, Chrysostomos Zannettis, Michael Chrysostomou, Stavros Panteli and Anthony Antoniou

Technologies 2022, 10(1), 26; https://doi.org/10.3390/technologies10010026 - 2 Feb 2022

Cited by 52 | Viewed by 20657

Abstract

This paper presents the design and implementation of iPONICS: an intelligent, low-cost IoT-based control and monitoring system for hydroponics greenhouses. The system is based on three types of sensor nodes. The main (master) node is responsible for controlling the pump, monitoring the quality [...] Read more.

This paper presents the design and implementation of iPONICS: an intelligent, low-cost IoT-based control and monitoring system for hydroponics greenhouses. The system is based on three types of sensor nodes. The main (master) node is responsible for controlling the pump, monitoring the quality of the water in the greenhouse and aggregating and transmitting the data from the slave nodes. Environment sensing slave nodes monitor the ambient conditions in the greenhouse and transmit the data to the main node. Security nodes monitor activity (movement in the area). The system monitors water quality and greenhouse temperature and humidity, ensuring that crops grow under optimal conditions according to hydroponics guidelines. Remote monitoring for the greenhouse keepers is facilitated by monitoring these parameters via connecting to a website. An innovative fuzzy inference engine determines the plant irrigation duration. The system is optimized for low power consumption in order to facilitate off-grid operation. Preliminary reliability analysis indicates that the system can tolerate various transient faults without requiring intervention. Full article

(This article belongs to the Special Issue MOCAST 2021)

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17 pages, 2806 KB

Open AccessEditor’s ChoiceArticle

User-Centric Design Methodology for mHealth Apps: The PainApp Paradigm for Chronic Pain

by Yiannis Koumpouros

Technologies 2022, 10(1), 25; https://doi.org/10.3390/technologies10010025 - 31 Jan 2022

Cited by 18 | Viewed by 6843

Abstract

The paper presents a user-centric methodology in order to design successful mobile health (mHealth) applications. In addition to the theoretical background, such an example is presented with an application targeting chronic pain. The pain domain was decided due to its significance in many [...] Read more.

The paper presents a user-centric methodology in order to design successful mobile health (mHealth) applications. In addition to the theoretical background, such an example is presented with an application targeting chronic pain. The pain domain was decided due to its significance in many aspects: its complexity, dispersion in the population, the financial burden it causes, etc. The paper presents a step-by-step plan in order to build mobile health applications. Participatory design and interdisciplinarity are only some of the critical issues towards the desired result. In the given example (development of the PainApp), a participatory design was followed with a team of seventeen stakeholders that drove the design and development phases. Three physicians, one behavioral scientist, three IT and UX experts, and ten patients collaborated together to develop the final solution. The several features implemented in the PainApp solution are presented in details. The application is threefold: it supports the management, reporting, and treatment effectiveness monitoring. The paper is giving details on the methodological approach while presenting insights on the actual plan and the steps followed for having a patient-centric solution. Key success factors and barriers to mobile health applications that support the need for such an approach are also presented. Full article

(This article belongs to the Section Information and Communication Technologies)

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14 pages, 359 KB

Open AccessArticle

Improving Effectiveness of a Coaching System through Preference Learning

by Martin Žnidaršič, Aljaž Osojnik, Peter Rupnik and Bernard Ženko

Technologies 2022, 10(1), 24; https://doi.org/10.3390/technologies10010024 - 31 Jan 2022

Viewed by 2534

Abstract

The paper describes an approach for indirect data-based assessment and use of user preferences in an unobtrusive sensor-based coaching system with the aim of improving coaching effectiveness. The preference assessments are used to adapt the reasoning components of the coaching system in a [...] Read more.

The paper describes an approach for indirect data-based assessment and use of user preferences in an unobtrusive sensor-based coaching system with the aim of improving coaching effectiveness. The preference assessments are used to adapt the reasoning components of the coaching system in a way to better align with the preferences of its users. User preferences are learned based on data that describe user feedback as reported for different coaching messages that were received by the users. The preferences are not learned directly, but are assessed through a proxy—classifications or probabilities of positive feedback as assigned by a predictive machine learned model of user feedback. The motivation and aim of such an indirect approach is to allow for preference estimation without burdening the users with interactive preference elicitation processes. A brief description of the coaching setting is provided in the paper, before the approach for preference assessment is described and illustrated on a real-world example obtained during the testing of the coaching system with elderly users. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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16 pages, 1087 KB

Open AccessArticle

Analysis of the Impact of Electrical and Timing Masking on Soft Error Rate Estimation in VLSI Circuits

by Pelopidas Tsoumanis, Georgios Ioannis Paliaroutis, Nestor Evmorfopoulos and George Stamoulis

Technologies 2022, 10(1), 23; https://doi.org/10.3390/technologies10010023 - 31 Jan 2022

Cited by 8 | Viewed by 3244

Abstract

Due to continuous CMOS technology downscaling, Integrated Circuits (ICs) have become more susceptible to radiation-induced hazards such as soft errors. Thus, to design radiation-hardened and reliable ICs, the Soft Error Rate (SER) estimation constitutes an essential procedure. An accurate SER evaluation is provided [...] Read more.

Due to continuous CMOS technology downscaling, Integrated Circuits (ICs) have become more susceptible to radiation-induced hazards such as soft errors. Thus, to design radiation-hardened and reliable ICs, the Soft Error Rate (SER) estimation constitutes an essential procedure. An accurate SER evaluation is provided based on a SPICE-oriented electrical masking analysis, combined with a TCAD characterization process. Furthermore, the proposed work analyzes the effect of a Static Timing Analysis (STA) methodology and the actual interconnection delay on SER evaluation. An analysis of the generated Single Event Multiple Transients (SEMTs) and the circuit operating frequency that are related to the SER estimation is also discussed. Various benchmarks, synthesized utilizing a 45 nm and 15 nm technology, are employed, and the experimental results demonstrate the SER variation as the device node scales down. Full article

(This article belongs to the Special Issue MOCAST 2021)

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16 pages, 4789 KB

Open AccessArticle

An Affordable Upper-Limb Exoskeleton Concept for Rehabilitation Applications

by Emanuele Palazzi, Luca Luzi, Eldison Dimo, Matteo Meneghetti, Rudy Vicario, Rafael Ferro Luzia, Rocco Vertechy and Andrea Calanca

Technologies 2022, 10(1), 22; https://doi.org/10.3390/technologies10010022 - 30 Jan 2022

Cited by 27 | Viewed by 8738

Abstract

In recent decades, many researchers have focused on the design and development of exoskeletons. Several strategies have been proposed to develop increasingly more efficient and biomimetic mechanisms. However, existing exoskeletons tend to be expensive and only available for a few people. This paper [...] Read more.

In recent decades, many researchers have focused on the design and development of exoskeletons. Several strategies have been proposed to develop increasingly more efficient and biomimetic mechanisms. However, existing exoskeletons tend to be expensive and only available for a few people. This paper introduces a new gravity-balanced upper-limb exoskeleton suited for rehabilitation applications and designed with the main objective of reducing the cost of the components and materials. Regarding mechanics, the proposed design significantly reduces the motor torque requirements, because a high cost is usually associated with high-torque actuation. Regarding the electronics, we aim to exploit the microprocessor peripherals to obtain parallel and real-time execution of communication and control tasks without relying on expensive RTOSs. Regarding sensing, we avoid the use of expensive force sensors. Advanced control and rehabilitation features are implemented, and an intuitive user interface is developed. To experimentally validate the functionality of the proposed exoskeleton, a rehabilitation exercise in the form of a pick-and-place task is considered. Experimentally, peak torques are reduced by 89% for the shoulder and by 84% for the elbow. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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10 pages, 1457 KB

Open AccessEditor’s ChoiceArticle

Results of Preliminary Studies on the Perception of the Relationships between Objects Presented in a Cartesian Space

by Ira Woodring and Charles Owen

Technologies 2022, 10(1), 20; https://doi.org/10.3390/technologies10010020 - 30 Jan 2022

Viewed by 2525

Abstract

Visualizations often use the paradigm of a Cartesian space for the presentation of objects and information. Unified Modeling Language (UML) is a visual language used to describe relationships in processes and systems and is heavily used in computer science and software engineering. Visualizations [...] Read more.

Visualizations often use the paradigm of a Cartesian space for the presentation of objects and information. Unified Modeling Language (UML) is a visual language used to describe relationships in processes and systems and is heavily used in computer science and software engineering. Visualizations are a powerful development tool, but are not necessarily accessible to all users, as individuals may differ in their level of visual ability or perceptual biases. Sonfication methods can be used to supplement or, in some cases, replace visual models. This paper describes two studies created to determine the ability of users to perceive relationships between objects in a Cartesian space when presented in a sonified form. Results from this study will be used to guide the creation of sonified UML software. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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20 pages, 1846 KB

Open AccessArticle

A Lightweight Messaging Protocol for Internet of Things Devices

by Justice Owusu Agyemang, Jerry John Kponyo, James Dzisi Gadze, Henry Nunoo-Mensah and Dantong Yu

Technologies 2022, 10(1), 21; https://doi.org/10.3390/technologies10010021 - 29 Jan 2022

Cited by 9 | Viewed by 7618

Abstract

The move towards intelligent systems has led to the evolution of IoT. This technological leap has over the past few years introduced significant improvements to various aspects of the human environment, such as health, commerce, transport, etc. IoT is data-centric; hence, it is [...] Read more.

The move towards intelligent systems has led to the evolution of IoT. This technological leap has over the past few years introduced significant improvements to various aspects of the human environment, such as health, commerce, transport, etc. IoT is data-centric; hence, it is required that the underlying protocols are scalable and sufficient to support the vast D2D communication. Several application layer protocols are being used for M2M communication protocols such as CoAP, MQTT, etc. Even though these messaging protocols have been designed for M2M communication, they are still not optimal for communications where message size and overhead are of much concern. This research paper presents a Lightweight Messaging Protocol (LiMP), which is a minified version of CoAP. We present a detailed protocol stack of the proposed messaging protocol and also perform a benchmark analysis of the protocol on some IoT devices. The proposed minified protocol achieves minimal overhead (a header size of 2 bytes) and has faster point-to-point communication from the benchmark analysis; for communication over LAN, the LiMP-TCP outperformed the CoAP-TCP by an average of 21% whereas that of LiMP-UDP was over 37%. For a device to remote server communication, LiMP outperformed CoAP by an average of 15%. Full article

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14 pages, 2847 KB

Open AccessEditor’s ChoiceArticle

On the Exploration of Automatic Building Extraction from RGB Satellite Images Using Deep Learning Architectures Based on U-Net

by Anastasios Temenos, Nikos Temenos, Anastasios Doulamis and Nikolaos Doulamis

Technologies 2022, 10(1), 19; https://doi.org/10.3390/technologies10010019 - 29 Jan 2022

Cited by 18 | Viewed by 4878

Abstract

Detecting and localizing buildings is of primary importance in urban planning tasks. Automating the building extraction process, however, has become attractive given the dominance of Convolutional Neural Networks (CNNs) in image classification tasks. In this work, we explore the effectiveness of the CNN-based [...] Read more.

Detecting and localizing buildings is of primary importance in urban planning tasks. Automating the building extraction process, however, has become attractive given the dominance of Convolutional Neural Networks (CNNs) in image classification tasks. In this work, we explore the effectiveness of the CNN-based architecture U-Net and its variations, namely, the Residual U-Net, the Attention U-Net, and the Attention Residual U-Net, in automatic building extraction. We showcase their robustness in feature extraction and information processing using exclusively RGB images, as they are a low-cost alternative to multi-spectral and LiDAR ones, selected from the SpaceNet 1 dataset. The experimental results show that U-Net achieves a

91.9 %

accuracy, whereas introducing residual blocks, attention gates, or a combination of both improves the accuracy of the vanilla U-Net to

93.6 %

,

94.0 %

, and

93.7 %

, respectively. Finally, the comparison between U-Net architectures and typical deep learning approaches from the literature highlights their increased performance in accurate building localization around corners and edges. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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3 pages, 147 KB

Open AccessEditorial

Acknowledgment to Reviewers of Technologies in 2021

by Technologies Editorial Office

Technologies 2022, 10(1), 18; https://doi.org/10.3390/technologies10010018 - 28 Jan 2022

Viewed by 2083

Abstract

Rigorous peer-reviews are the basis of high-quality academic publishing [...] Full article

18 pages, 1780 KB

Open AccessEditor’s ChoiceArticle

Stacking-Based Ensemble Learning Method for Multi-Spectral Image Classification

by Tagel Aboneh, Abebe Rorissa and Ramasamy Srinivasagan

Technologies 2022, 10(1), 17; https://doi.org/10.3390/technologies10010017 - 26 Jan 2022

Cited by 38 | Viewed by 6802

Abstract

Higher dimensionality, Hughes phenomenon, spatial resolution of image data, and presence of mixed pixels are the main challenges in a multi-spectral image classification process. Most of the classical machine learning algorithms suffer from scoring optimal classification performance over multi-spectral image data. In this [...] Read more.

Higher dimensionality, Hughes phenomenon, spatial resolution of image data, and presence of mixed pixels are the main challenges in a multi-spectral image classification process. Most of the classical machine learning algorithms suffer from scoring optimal classification performance over multi-spectral image data. In this study, we propose stack-based ensemble-based learning approach to optimize image classification performance. In addition, we integrate the proposed ensemble learning with XGBoost method to further improve its classification accuracy. To conduct the experiment, the Landsat image data has been acquired from Bishoftu town located in the Oromia region of Ethiopia. The current study’s main objective was to assess the performance of land cover and land use analysis using multi-spectral image data. Results from our experiment indicate that, the proposed ensemble learning method outperforms any strong base classifiers with 99.96% classification performance accuracy. Full article

(This article belongs to the Special Issue Multimedia Indexing and Retrieval)

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23 pages, 5508 KB

Open AccessEditor’s ChoiceArticle

Novel Benes Network Routing Algorithm and Hardware Implementation

by Dimitris Nikolaidis, Panos Groumas, Christos Kouloumentas and Hercules Avramopoulos

Technologies 2022, 10(1), 16; https://doi.org/10.3390/technologies10010016 - 25 Jan 2022

Cited by 7 | Viewed by 8920

Abstract

Benes/Clos networks constitute a particularly important part of interconnection networks and have been used in numerous areas, such as multi-processor systems, data centers and on-chip networks. They have also attracted great interest in the field of optical communications due to the increasing popularity [...] Read more.

Benes/Clos networks constitute a particularly important part of interconnection networks and have been used in numerous areas, such as multi-processor systems, data centers and on-chip networks. They have also attracted great interest in the field of optical communications due to the increasing popularity of optical switches based on these architectures. There are numerous algorithms aimed at routing these types of networks, with varying degrees of utility. Linear algorithms, such as Sun Tsu and Opferman, were historically the first attempt to standardize the routing procedure of this types of networks. They require matrix-based calculations, which are very demanding in terms of resources and in some cases involve backtracking, which impairs their efficiency. Parallel solutions, such as Lee’s algorithm, were introduced later and provide a different answer that satisfy the requirements of high-performance networks. They are, however, extremely complex and demand even more resources. In both cases, hardware implementations reflect their algorithmic characteristics. In this paper, we attempt to design an algorithm that is simple enough to be implemented on a small field programmable gate array board while simultaneously efficient enough to be used in practical scenarios. The design itself is of a generic nature; therefore, its behavior across different sizes (8 × 8, 16 × 16, 32 × 32, 64 × 64) is examined. The platform of implementation is a medium range FPGA specifically selected to represent the average hardware prototyping device. In the end, an overview of the algorithm’s imprint on the device is presented alongside other approaches, which include both hard and soft computing techniques. Full article

(This article belongs to the Section Information and Communication Technologies)

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22 pages, 587 KB

Open AccessArticle

Self-Organizing and Self-Explaining Pervasive Environments by Connecting Smart Objects and Applications

by Börge Kordts, Bennet Gerlach and Andreas Schrader

Technologies 2022, 10(1), 15; https://doi.org/10.3390/technologies10010015 - 24 Jan 2022

Cited by 2 | Viewed by 3074

Abstract

In the past decade, pervasive environments have progressed from promising research concepts to available products present in our everyday lives. By connecting multiple smart objects, device ensembles can be formed to assist users in performing tasks. Furthermore, smart objects can be used to [...] Read more.

In the past decade, pervasive environments have progressed from promising research concepts to available products present in our everyday lives. By connecting multiple smart objects, device ensembles can be formed to assist users in performing tasks. Furthermore, smart objects can be used to control applications, that, in turn, can be used to control other smart objects. As manual configuration is often time-consuming, an automatic connection of the components may present a useful tool, which should take various aspects into account. While dynamically connecting these components allows for solutions tailored to the needs and respective tasks of a user, it obfuscates the handling and ultimately may decrease usability. Self-descriptions have been proposed to overcome this issue for ensembles of smart objects. For a more extensive approach, descriptions of applications in pervasive environments need to be addressed as well. Based on previous research in the context of self-explainability of smart objects, we propose a description language as well as a framework to support self-explaining ambient applications (applications that are used within smart environments). The framework can be used to manually or automatically connect smart objects as well as ambient applications and to realize self-explainability for these interconnected device and application ensembles. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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15 pages, 782 KB

Open AccessEditor’s ChoiceArticle

Efficient Stochastic Computing FIR Filtering Using Sigma-Delta Modulated Signals

by Nikos Temenos, Anastasis Vlachos and Paul P. Sotiriadis

Technologies 2022, 10(1), 14; https://doi.org/10.3390/technologies10010014 - 20 Jan 2022

Cited by 7 | Viewed by 3273

Abstract

This work presents a soft-filtering digital signal processing architecture based on sigma-delta modulators and stochastic computing. A sigma-delta modulator converts the input high-resolution signal to a single-bit stream enabling filtering structures to be realized using stochastic computing’s negligible-area multipliers. Simulation in the spectral [...] Read more.

This work presents a soft-filtering digital signal processing architecture based on sigma-delta modulators and stochastic computing. A sigma-delta modulator converts the input high-resolution signal to a single-bit stream enabling filtering structures to be realized using stochastic computing’s negligible-area multipliers. Simulation in the spectral domain demonstrates the filter’s proper operation and its roll-off behavior, as well as the signal-to-noise ratio improvement using the sigma-delta modulator, compared to typical stochastic computing filter realizations. The proposed architecture’s hardware advantages are showcased with synthesis results for two FIR filters using FPGA and synopsys tools, while comparisons with standard stochastic computing-based hardware realizations, as well as with conventional binary ones, demonstrate its efficacy. Full article

(This article belongs to the Special Issue MOCAST 2021)

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12 pages, 1985 KB

Open AccessEditor’s ChoiceArticle

IoT Framework for Measurement and Precision Agriculture: Predicting the Crop Using Machine Learning Algorithms

by Kalaiselvi Bakthavatchalam, Balaguru Karthik, Vijayan Thiruvengadam, Sriram Muthal, Deepa Jose, Ketan Kotecha and Vijayakumar Varadarajan

Technologies 2022, 10(1), 13; https://doi.org/10.3390/technologies10010013 - 20 Jan 2022

Cited by 95 | Viewed by 12088

Abstract

IoT architectures facilitate us to generate data for large and remote agriculture areas and the same can be utilized for Crop predictions using this machine learning algorithm. Recommendations are based on the following N, P, K, pH, Temperature, Humidity, and Rainfall these attributes [...] Read more.

IoT architectures facilitate us to generate data for large and remote agriculture areas and the same can be utilized for Crop predictions using this machine learning algorithm. Recommendations are based on the following N, P, K, pH, Temperature, Humidity, and Rainfall these attributes decide the crop to be recommended. The data set has 2200 instances and 8 attributes. Nearly 22 different crops are recommended for a different combination of 8 attributes. Using the supervised learning method, the optimum model is attained using selected machine learning algorithms in WEKA. The Machine learning algorithm selected for classifying is multilayer perceptron rules-based classifier JRip, and decision table classifier. The main objective of this case study is to end up with a model which predicts the high yield crop and precision agriculture. The proposed system modeling incorporates the trending technology, IoT, and Agriculture needy measurements. The performance assessed by the selected classifiers is 98.2273%, the Weighted average Receiver Operator Characteristics is 1 with the maximum time taken to build the model being 8.05 s. Full article

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15 pages, 332 KB

Open AccessEditor’s ChoiceReview

A Review of Efficient Real-Time Decision Making in the Internet of Things

by Kyoung-Don Kang

Technologies 2022, 10(1), 12; https://doi.org/10.3390/technologies10010012 - 19 Jan 2022

Cited by 13 | Viewed by 6215

Abstract

Emerging applications of IoT (the Internet of Things), such as smart transportation, health, and energy, are envisioned to greatly enhance the societal infrastructure and quality of life of individuals. In such innovative IoT applications, cost-efficient real-time decision-making is critical to facilitate, for example, [...] Read more.

Emerging applications of IoT (the Internet of Things), such as smart transportation, health, and energy, are envisioned to greatly enhance the societal infrastructure and quality of life of individuals. In such innovative IoT applications, cost-efficient real-time decision-making is critical to facilitate, for example, effective transportation management and healthcare. In this paper, we formally define real-time decision tasks in IoT, review cutting-edge approaches that aim to efficiently schedule real-time decision tasks to meet their timing and data freshness constraints, review state-of-the-art approaches for efficient sensor data analytics in IoT, and discuss future research directions. Full article

(This article belongs to the Section Information and Communication Technologies)

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9 pages, 2280 KB

Open AccessArticle

Water-Assisted Perovskite Quantum Dots with High Optical Properties

by Masaaki Yokoyama, Ryota Sato, Junya Enomoto, Naoaki Oshita, Taisei Kimura, Keisuke Kikuchi, Satoshi Asakura, Kazuki Umemoto and Akito Masuhara

Technologies 2022, 10(1), 11; https://doi.org/10.3390/technologies10010011 - 17 Jan 2022

Cited by 7 | Viewed by 3583

Abstract

Lead halide perovskite quantum dots (PeQDs) have excellent optical properties, such as narrow emission spectra (FWHM: 18–30 nm), a tunable bandgap (λ_PL: 420–780 nm), and excellent photoluminescence quantum yields (PLQYs: >90%). PeQDs are known as a material that is easily decomposed [...] Read more.

Lead halide perovskite quantum dots (PeQDs) have excellent optical properties, such as narrow emission spectra (FWHM: 18–30 nm), a tunable bandgap (λ_PL: 420–780 nm), and excellent photoluminescence quantum yields (PLQYs: >90%). PeQDs are known as a material that is easily decomposed when exposed to water in the atmosphere, resulting in causing PeQDs to lower performance. On the other hand, according to the recent reports, adding water after preparing the PeQD dispersion decomposed the PeQD surface defects, resulting in improving their PLQY. Namely, controlling the amount of assisting water during the preparation of the PeQDs is a significantly critical factor to determining their optical properties and device applications. In this paper, our research group discovered the novel effects of the small amount of water to their optical properties when preparing the PeQDs. According to the TEM Images, the PeQDs particle size was clearly increased after water-assisting. In addition, XPS measurement showed that the ratio of Br/Pb achieved to be close to three. Namely, by passivating the surface defect using Ostwald ripening, the prepared PeQDs achieved a high PLQY of over 95%. Full article

(This article belongs to the Special Issue Smart Systems (SmaSys2021))

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8 pages, 6443 KB

Open AccessArticle

Enhanced Air Stability of Perovskite Quantum Dots by Manganese Passivation

by Ryota Sato, Kazuki Umemoto, Satoshi Asakura and Akito Masuhara

Technologies 2022, 10(1), 10; https://doi.org/10.3390/technologies10010010 - 16 Jan 2022

Cited by 3 | Viewed by 3725

Abstract

Organic-inorganic perovskite quantum dots (PeQDs) have attracted attention due to their excellent optical properties, e.g., high photoluminescence quantum yields (PLQYs; >70%), a narrow full width at half maximum (FWHM; 25 nm or less), and color tunability adjusted by the halide components in an [...] Read more.

Organic-inorganic perovskite quantum dots (PeQDs) have attracted attention due to their excellent optical properties, e.g., high photoluminescence quantum yields (PLQYs; >70%), a narrow full width at half maximum (FWHM; 25 nm or less), and color tunability adjusted by the halide components in an entire tunability (from 450 nm to 730 nm). On the other hand, PeQD stability against air, humidity, and thermal conditions has still not been enough, which disturbs their application. To overcome these issues, with just a focus on the air stability, Mn²⁺ ion passivated perovskite quantum dots (Mn/MAPbBr₃ QDs) were prepared. Mn²⁺ could be expected to contract the passivating layer against the air condition because the Mn²⁺ ion was changed to the oxidized Mn on PeQDs under the air conditions. In this research, Mn/MAPbBr₃ QDs were successfully prepared by ligand-assisted reprecipitation (LARP) methods. Surprisingly, Mn/MAPbBr₃ QD films showed more than double PLQY stability over 4 months compared with pure MAPbBr₃ ones against the air, which suggested that oxidized Mn worked as a passivating layer. Improving the PeQD stability is significantly critical for their application. Full article

(This article belongs to the Special Issue Smart Systems (SmaSys2021))

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22 pages, 13186 KB

Open AccessEditor’s ChoiceReview

3D Scanning/Printing: A Technological Stride in Sculpture

by G.-Fivos Sargentis, Evangelia Frangedaki, Michalis Chiotinis, Demetris Koutsoyiannis, Stephanos Camarinopoulos, Alexios Camarinopoulos and Nikos D. Lagaros

Technologies 2022, 10(1), 9; https://doi.org/10.3390/technologies10010009 - 14 Jan 2022

Cited by 21 | Viewed by 9589

Abstract

The creation of innovative tools, objects and artifacts that introduce abstract ideas in the real world is a necessary step for the evolution process and characterize the creative capacity of civilization. Sculpture is based on the available technology for its creation process and [...] Read more.

The creation of innovative tools, objects and artifacts that introduce abstract ideas in the real world is a necessary step for the evolution process and characterize the creative capacity of civilization. Sculpture is based on the available technology for its creation process and is strongly related to the level of technological sophistication of each era. This paper analyzes the evolution of basic sculpture techniques (carving, lost-wax casting and 3D scanning/printing), and their importance as a culture footprint. It also presents and evaluates the added creative capacities of each technological step and the different methods of 3D scanning/printing concerning sculpture. It is also an attempt to define the term “material poetics”, which is connected to sculpture artifacts. We conclude that 3D scanning/printing is an important sign of civilization, although artifacts lose a part of material poetics with additive manufacturing. Subsequently, there are various causes of the destruction of sculptures, leaving a hole in the history of art. Finally, this paper showcases the importance of 3D scanning/printing in salvaging cultural heritage, as it has radically altered the way we “backup” objects. Full article

(This article belongs to the Section Manufacturing Technology)

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17 pages, 4039 KB

Open AccessEditor’s ChoiceArticle

Assistive Technologies for Supporting the Wellbeing of Older Adults

by Ioanna Dratsiou, Annita Varella, Evangelia Romanopoulou, Oscar Villacañas, Sara Cooper, Pavlos Isaris, Manex Serras, Luis Unzueta, Tatiana Silva, Alexia Zurkuhlen, Malcolm MacLachlan and Panagiotis D. Bamidis

Technologies 2022, 10(1), 8; https://doi.org/10.3390/technologies10010008 - 14 Jan 2022

Cited by 14 | Viewed by 6506

Abstract

As people age, they are more likely to develop multiple chronic diseases and experience a decline in some of their physical and cognitive functions, leading to the decrease in their ability to live independently. Innovative technology-based interventions tailored to older adults’ functional levels [...] Read more.

As people age, they are more likely to develop multiple chronic diseases and experience a decline in some of their physical and cognitive functions, leading to the decrease in their ability to live independently. Innovative technology-based interventions tailored to older adults’ functional levels and focused on healthy lifestyles are considered imperative. This work proposed a framework of active and healthy ageing through the integration of a broad spectrum of digital solutions into an open Pan-European technological platform in the context of the SHAPES project, an EU-funded innovation action. In conclusion, the SHAPES project can potentially engage older adults in a holistic technological ecosystem and, therefore, facilitate the maintenance of a high-quality standard of life. Full article

(This article belongs to the Section Assistive Technologies)

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10 pages, 4927 KB

Open AccessEditor’s ChoiceArticle

A Simulated Environment for Robot Vision Experiments

by Christos Sevastopoulos, Stasinos Konstantopoulos, Keshav Balaji, Mohammad Zaki Zadeh and Fillia Makedon

Technologies 2022, 10(1), 7; https://doi.org/10.3390/technologies10010007 - 12 Jan 2022

Cited by 6 | Viewed by 3584

Abstract

Training on simulation data has proven invaluable in applying machine learning in robotics. However, when looking at robot vision in particular, simulated images cannot be directly used no matter how realistic the image rendering is, as many physical parameters (temperature, humidity, wear-and-tear in [...] Read more.

Training on simulation data has proven invaluable in applying machine learning in robotics. However, when looking at robot vision in particular, simulated images cannot be directly used no matter how realistic the image rendering is, as many physical parameters (temperature, humidity, wear-and-tear in time) vary and affect texture and lighting in ways that cannot be encoded in the simulation. In this article we propose a different approach for extracting value from simulated environments: although neither of the trained models can be used nor are any evaluation scores expected to be the same on simulated and physical data, the conclusions drawn from simulated experiments might be valid. If this is the case, then simulated environments can be used in early-stage experimentation with different network architectures and features. This will expedite the early development phase before moving to (harder to conduct) physical experiments in order to evaluate the most promising approaches. In order to test this idea we created two simulated environments for the Unity engine, acquired simulated visual datasets, and used them to reproduce experiments originally carried out in a physical environment. The comparison of the conclusions drawn in the physical and the simulated experiments is promising regarding the validity of our approach. Full article

(This article belongs to the Collection Selected Papers from the PETRA Conference Series)

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