Open AccessArticle
Feedback-Based Admission Control for Firm Real-Time Task Allocation with Dynamic Voltage and Frequency Scaling
Computers 2018, 7(2), 26; doi:10.3390/computers7020026 -
Abstract
Feedback-based mechanisms can be employed to monitor the performance of Multiprocessor Systems-on-Chips (MPSoCs) and steer the task execution even if the exact knowledge of the workload is unknown a priori. In particular, traditional proportional-integral controllers can be used with firm real-time tasks to
[...] Read more.
Feedback-based mechanisms can be employed to monitor the performance of Multiprocessor Systems-on-Chips (MPSoCs) and steer the task execution even if the exact knowledge of the workload is unknown a priori. In particular, traditional proportional-integral controllers can be used with firm real-time tasks to either admit them to the processing cores or reject in order not to violate the timeliness of the already admitted tasks. During periods with a lower computational power demand, dynamic voltage and frequency scaling (DVFS) can be used to reduce the dissipation of energy in the cores while still not violating the tasks’ time constraints. Depending on the workload pattern and weight, platform size and the granularity of DVFS, energy savings can reach even 60% at the cost of a slight performance degradation. Full article
Figures

Figure 1

Open AccessArticle
Scheduling and Tuning for Low Energy in Heterogeneous and Configurable Multicore Systems
Computers 2018, 7(2), 25; doi:10.3390/computers7020025 -
Abstract
Heterogeneous and configurable multicore systems provide hardware specialization to meet disparate application hardware requirements. However, effective multicore system specialization can require a priori knowledge of the applications, application profiling information, and/or dynamic hardware tuning to schedule and execute applications on the most energy
[...] Read more.
Heterogeneous and configurable multicore systems provide hardware specialization to meet disparate application hardware requirements. However, effective multicore system specialization can require a priori knowledge of the applications, application profiling information, and/or dynamic hardware tuning to schedule and execute applications on the most energy efficient cores. Furthermore, even though highly disparate core heterogeneity and/or highly configurable parameters with numerous potential parameter values result in more fine-grained specialization and higher energy savings potential, these large design spaces are challenging to efficiently explore. To address these challenges, we propose a novel configuration-subsetted heterogeneous and configurable multicore system, wherein each core offers a small subset of the design space, and propose a novel scheduling and tuning (SaT) algorithm to efficiently exploit the energy savings potential of this system. Our proposed architecture and algorithm require no a priori application knowledge or profiling, and incur minimal runtime overhead. Results reveal energy savings potential and insights on energy trade-offs in heterogeneous, configurable systems. Full article
Figures

Figure 1

Open AccessArticle
Bridging the Gap between ABM and MAS: A Disaster-Rescue Simulation Using Jason and NetLogo
Computers 2018, 7(2), 24; doi:10.3390/computers7020024 -
Abstract
An agent is an autonomous computer system situated in an environment to fulfill a design objective. Multi-Agent Systems aim to solve problems in a flexible and robust way by assembling sets of agents interacting in cooperative or competitive ways for the sake of
[...] Read more.
An agent is an autonomous computer system situated in an environment to fulfill a design objective. Multi-Agent Systems aim to solve problems in a flexible and robust way by assembling sets of agents interacting in cooperative or competitive ways for the sake of possibly common objectives. Multi-Agent Systems have been applied to several domains ranging from many industrial sectors, e-commerce, health and even entertainment. Agent-Based Modeling, a sort of Multi-Agent Systems, is a technique used to study complex systems in a wide range of domains. A natural or social system can be represented, modeled and explained through a simulation based on agents and interactions. Such a simulation can comprise a variety of agent architectures like reactive and cognitive agents. Despite cognitive agents being highly relevant to simulate social systems due their capability of modelling aspects of human behaviour ranging from individuals to crowds, they still have not been applied extensively. A challenging and socially relevant domain are the Disaster-Rescue simulations that can benefit from using cognitive agents to develop a realistic simulation. In this paper, a Multi-Agent System applied to the Disaster-Rescue domain involving cognitive agents based on the Belief–Desire–Intention architecture is presented. The system aims to bridge the gap in combining Agent-Based Modelling and Multi-Agent Systems approaches by integrating two major platforms in the field of Agent-Based Modeling and Belief-Desire Intention multi-agent systems, namely, NetLogo and Jason. Full article
Figures

Figure 1

Open AccessArticle
Failure Detection of Composites with Control System Corrective Response in Drone System Applications
Computers 2018, 7(2), 23; doi:10.3390/computers7020023 -
Abstract
The paper describes a novel method for the detection of damage in carbon composites as used in drone frames. When damage is detected a further novel corrective response is initiated in the quadcopter flight controller to switch from a four-arm control system to
[...] Read more.
The paper describes a novel method for the detection of damage in carbon composites as used in drone frames. When damage is detected a further novel corrective response is initiated in the quadcopter flight controller to switch from a four-arm control system to a three-arm control system. This is made possible as a symmetrical frame is utilized, which allows for a balanced weight distribution between both the undamaged quadcopter and the fallback tri-copter layout. The resulting work allows for continued flight where this was not previously possible. Further developing work includes improved flight stability with the aid of an underslung load model. This is beneficial to the quadcopter as a damaged arm attached to the main body by the motor wires behaves as an underslung load. The underslung load works are also transferable in a dual master and slave drone system where the master drone transports a smaller slave drone by a tether, which acts as an underslung load. Full article
Figures

Figure 1

Open AccessArticle
Levels for Hotline Miami 2: Wrong Number Using Procedural Content Generations
Computers 2018, 7(2), 22; doi:10.3390/computers7020022 -
Abstract
Procedural Content Generation is the automatic process for generating game content in order to allow for a decrease in developer resources while adding to the replayability of a digital game. It has been found to be highly effective as a method when utilized
[...] Read more.
Procedural Content Generation is the automatic process for generating game content in order to allow for a decrease in developer resources while adding to the replayability of a digital game. It has been found to be highly effective as a method when utilized in rougelike games, of which Hotline Miami 2: Wrong Number shares a number of factors. Search based procedural content, in this case, a genetic algorithm, allows for the creation of levels which meet with a number of designer set requirements. The generator proposed provides for an automatic creation of game content for a commercially available game: the level design, object placement, and enemy placement. Full article
Figures

Figure 1

Open AccessFeature PaperArticle
Low Effort Design Space Exploration Methodology for Configurable Caches
Computers 2018, 7(2), 21; doi:10.3390/computers7020021 -
Abstract
Designers can reduce design space exploration time and efforts using the design space subsetting method that removes energy-redundant configurations. However, the subsetting method requires a priori knowledge of all applications. We analyze the impact of a priori application knowledge on the subset quality
[...] Read more.
Designers can reduce design space exploration time and efforts using the design space subsetting method that removes energy-redundant configurations. However, the subsetting method requires a priori knowledge of all applications. We analyze the impact of a priori application knowledge on the subset quality by varying the amount of a priori application information available to designers during design time from no information to a general knowledge of the application domain. The results showed that only a small set of applications representative of the anticipated applications’ general domains alleviated the design efforts and was sufficient to provide energy savings within 5.6% of the complete, unsubsetted design space. Furthermore, since using a small set of applications was likely to reduce the design space exploration time, we analyze and quantify the impact of a priori applications knowledge on the speedup in the execution time to select the desired configurations. The results revealed that a basic knowledge of the anticipated applications reduced the subset design space exploration time by up to 6.6X. Full article
Figures

Figure 1

Open AccessFeature PaperArticle
Battery Modelling and Simulation Using a Programmable Testing Equipment
Computers 2018, 7(2), 20; doi:10.3390/computers7020020 -
Abstract
In this paper, the study and modelling of a lithium-ion battery cell is presented. To test the considered cell, a battery testing system was built using two programmable power units: an electronic load and a power supply. To communicate with them, a software/hardware
[...] Read more.
In this paper, the study and modelling of a lithium-ion battery cell is presented. To test the considered cell, a battery testing system was built using two programmable power units: an electronic load and a power supply. To communicate with them, a software/hardware interface was implemented within the National Instruments (NI) LabVIEW environment. This dedicated laboratory equipment can be used to apply charging/discharging cycles according to user defined load profiles. The battery modelling and the parameters identification procedure are described. The model was used to estimate the State Of Charge (SOC) under dynamic loading conditions. The most spread techniques used in the field of battery modelling and SOC estimation are implemented and compared. Full article
Figures

Figure 1

Open AccessArticle
Mobile Educational Augmented Reality Games: A Systematic Literature Review and Two Case Studies
Computers 2018, 7(1), 19; doi:10.3390/computers7010019 -
Abstract
Augmented reality (AR) has evolved from research projects into mainstream applications that cover diverse fields, such as entertainment, health, business, tourism and education. In particular, AR games, such as Pokémon Go, have contributed to introducing the AR technology to the general public. The
[...] Read more.
Augmented reality (AR) has evolved from research projects into mainstream applications that cover diverse fields, such as entertainment, health, business, tourism and education. In particular, AR games, such as Pokémon Go, have contributed to introducing the AR technology to the general public. The proliferation of modern smartphones and tablets with large screens, cameras, and high processing power has ushered in mobile AR applications that can provide context-sensitive content to users whilst freeing them to explore the context. To avoid ambiguity, I define mobile AR as a type of AR where a mobile device (smartphone or tablet) is used to display and interact with virtual content that is overlaid on top of a real-time camera feed of the real world. Beyond being mere entertainment, AR and games have been shown to possess significant affordances for learning. Although previous research has done a decent job of reviewing research on educational AR applications, I identified a need for a comprehensive review on research related to educational mobile AR games (EMARGs). This paper explored the research landscape on EMARGs over the period 2012–2017 through a systematic literature review complemented by two case studies in which the author participated. After a comprehensive literature search and filtering, I analyzed 31 EMARGs from the perspectives of technology, pedagogy, and gaming. Moreover, I presented an analysis of 26 AR platforms that can be used to create mobile AR applications. I then discussed the results in depth and synthesized my interpretations into 13 guidelines for future EMARG developers. Full article
Figures

Figure 1

Open AccessArticle
A New Method of Histogram Computation for Efficient Implementation of the HOG Algorithm
Computers 2018, 7(1), 18; doi:10.3390/computers7010018 -
Abstract
In this paper we introduce a new histogram computation method to be used within the histogram of oriented gradients (HOG) algorithm. The new method replaces the arctangent with the slope computation and the classical magnitude allocation based on interpolation with a simpler algorithm.
[...] Read more.
In this paper we introduce a new histogram computation method to be used within the histogram of oriented gradients (HOG) algorithm. The new method replaces the arctangent with the slope computation and the classical magnitude allocation based on interpolation with a simpler algorithm. The new method allows a more efficient implementation of HOG in general, and particularly in field-programmable gate arrays (FPGAs), by considerably reducing the area (thus increasing the level of parallelism), while maintaining very close classification accuracy compared to the original algorithm. Thus, the new method is attractive for many applications, including car detection and classification. Full article
Figures

Figure 1

Open AccessEditorial
Editorial of the Special Issue of the 10th Workshop on Biomedical and Bioinformatics Challenges for Computer Science—BBC 2017
Computers 2018, 7(1), 17; doi:10.3390/computers7010017 -
Abstract
In this special issue, we present two of the papers presented at the 10th Workshop on Biomedical and Bioinformatics Challenges for Computer Science—BBC2017, held in Zurich, 12–14 June 2017. Full article
Open AccessArticle
Improved Capacity and Fairness of Massive Machine Type Communications in Millimetre Wave 5G Network
Computers 2018, 7(1), 16; doi:10.3390/computers7010016 -
Abstract
In the Fifth Generation (5G) wireless standard, the Internet of Things (IoT) will interconnect billions of Machine Type Communications (MTC) devices. Fixed and mobile wearable devices and sensors are expected to contribute to the majority of IoT traffic. MTC device mobility has been
[...] Read more.
In the Fifth Generation (5G) wireless standard, the Internet of Things (IoT) will interconnect billions of Machine Type Communications (MTC) devices. Fixed and mobile wearable devices and sensors are expected to contribute to the majority of IoT traffic. MTC device mobility has been considered with three speeds, namely zero (fixed) and medium and high speeds of 30 and 100 kmph. Different values for device mobility are used to simulate the impact of device mobility on MTC traffic. This work demonstrates the gain of using distributed antennas on MTC traffic in terms of spectral efficiency and fairness among MTC devices, which affects the number of devices that can be successfully connected. The mutual use of Distributed Base Stations (DBS) with Remote Radio Units (RRU) and the adoption of the millimetre wave band, particularly in the 26 GHz range, have been considered the key enabling technologies for addressing MTC traffic growth. An algorithm has been set to schedule this type of traffic and to show whether MTC devices completed their traffic upload or failed to reach the margin. The gains of the new architecture have been demonstrated in terms of spectral efficiency, data throughput and the fairness index. Full article
Figures

Figure 1

Open AccessArticle
Users’ Perceptions Using Low-End and High-End Mobile-Rendered HMDs: A Comparative Study
Computers 2018, 7(1), 15; doi:10.3390/computers7010015 -
Abstract
Currently, it is possible to combine Mobile-Rendered Head-Mounted Displays (MR HMDs) with smartphones to have Augmented Reality platforms. The differences between these types of platforms can affect the user’s experiences and satisfaction. This paper presents a study that analyses the user’s perception when
[...] Read more.
Currently, it is possible to combine Mobile-Rendered Head-Mounted Displays (MR HMDs) with smartphones to have Augmented Reality platforms. The differences between these types of platforms can affect the user’s experiences and satisfaction. This paper presents a study that analyses the user’s perception when using the same Augmented Reality app with two MR HMD (low-end and high-end). Our study evaluates the user’s experience taking into account several factors (control, sensory, distraction, ergonomics and realism). An Augmalpha-lowerented Reality app was developed to carry out the comparison for two MR HMDs. The application had exactly the same visual appearance and functionality for both devices. Forty adults participated in our study. From the results, there were no statistically significant differences for the users’ experience for the different factors when using the two MR HMDs, except for the ergonomic factors in favour of the high-end MR HMD. Even though the scores for the high-end MR HMD were higher in nearly all of the questions, both MR HMDs provided a very satisfying viewing experience with very high scores. The results were independent of gender and age. The participants rated the high-end MR HMD as the best one. Nevertheless, when they were asked which MR HMD they would buy, the participants chose the low-end MR HMD taking into account its price. Full article
Figures

Figure 1

Open AccessEditorial
Editorial of the Special Issue on Quantified Self and Personal Informatics
Computers 2018, 7(1), 14; doi:10.3390/computers7010014 -
Abstract
In recent years, we witnessed the spreading of a plethora of wearable and mobile technologies allowing for a continuous and “transparent” gathering of personal data [...] Full article
Open AccessArticle
CPS-Based Smart Warehouse for Industry 4.0: A Survey of the Underlying Technologies
Computers 2018, 7(1), 13; doi:10.3390/computers7010013 -
Abstract
This paper discusses how the state-of-the-art techniques in cyber-physical systems facilitate building smart warehouses to achieve the promising vision of industry 4.0. We focus on four significant issues when applying CPS techniques in smart warehouses. First, efficient CPS data collection: when limited
[...] Read more.
This paper discusses how the state-of-the-art techniques in cyber-physical systems facilitate building smart warehouses to achieve the promising vision of industry 4.0. We focus on four significant issues when applying CPS techniques in smart warehouses. First, efficient CPS data collection: when limited communication bandwidth meets numerous CPS devices, we need to make more effort to study efficient wireless communication scheduling strategies. Second, accurate and robust localization: localization is the basis for many fundamental operations in smart warehouses, but still needs to be improved from various aspects like accuracy and robustness. Third, human activity recognition: human activity recognition can be applied in human–computer interaction for remote machine operations. Fourth, multi-robot collaboration: smart robots will take the place of humans to accomplish most tasks particularly in a harsh environment, and smart and fully-distributed robot collaborating algorithms should be investigated. Finally, we point out some challenging issues in the future CPS-based smart warehouse, which could open some new research directions. Full article
Figures

Figure 1

Open AccessArticle
Visualizing the Provenance of Personal Data Using Comics
Computers 2018, 7(1), 12; doi:10.3390/computers7010012 -
Abstract
Personal health data is acquired, processed, stored, and accessed using a variety of different devices, applications, and services. These are often complex and highly connected. Therefore, use or misuse of the data is hard to detect for people, if they are not capable
[...] Read more.
Personal health data is acquired, processed, stored, and accessed using a variety of different devices, applications, and services. These are often complex and highly connected. Therefore, use or misuse of the data is hard to detect for people, if they are not capable to understand the trace (i.e., the provenance) of that data. We present a visualization technique for personal health data provenance using comic strips. Each strip of the comic represents a certain activity, such as entering data using a smartphone application, storing or retrieving data on a cloud service, or generating a diagram from the data. The comic strips are generated automatically using recorded provenance graphs. The easy-to-understand comics enable all people to notice crucial points regarding their data such as, for example, privacy violations. Full article
Figures

Figure 1

Open AccessEditorial
Acknowledgement to Reviewers of Computers in 2017
Computers 2018, 7(1), 11; doi:10.3390/computers7010011 -
Abstract
Peer review is an essential part in the publication process, ensuring that Computers maintains high quality standards for its published papers.[...] Full article
Open AccessArticle
High-Precision Control of a Piezo-Driven Nanopositioner Using Fuzzy Logic Controllers
Computers 2018, 7(1), 10; doi:10.3390/computers7010010 -
Abstract
This paper presents single- and dual-loop fuzzy control schemes to precisely control the piezo-driven nanopositioner in the x- and y-axis directions. Various issues are associated with this control problem, such as low stability margin due to the sharp resonant peak, nonlinear
[...] Read more.
This paper presents single- and dual-loop fuzzy control schemes to precisely control the piezo-driven nanopositioner in the x- and y-axis directions. Various issues are associated with this control problem, such as low stability margin due to the sharp resonant peak, nonlinear dynamics, parameter uncertainty, etc. As such, damping controllers are often utilised to damp the mechanical resonance of the nanopositioners. The Integral Resonant Controller (IRC) is used in this paper as a damping controller to damp the mechanical resonance. A further inherent problem is the hysteresis phenomenon (disturbance), which leads to degrading the positioning performance (accuracy) of the piezo-driven stage. The common approach to treat this disturbance is to invoke tracking controllers in a closed-loop feedback scheme in conjunction with the damping controllers. The traditional approach uses the Integral Controller (I) or Proportional Integral (PI) as a tracking controller, whereas this paper introduces the Proportional and Integral (PI)-like Fuzzy Logic Controller (FLC) as a tracking controller. The effectiveness of the proposed control schemes over conventional schemes is confirmed through comparative simulation studies, and results are presented. The stability boundaries of the proposed control schemes are determined in the same way as with a conventional controller. Robustness against variations in the resonant frequency of the proposed control schemes is verified. Full article
Figures

Figure 1

Open AccessArticle
An Improvement on Remote User Authentication Schemes Using Smart Cards
Computers 2018, 7(1), 9; doi:10.3390/computers7010009 -
Abstract
In 2010, Yeh et al. proposed two robust remote user authentication schemes using smart cards; their claims were such that their schemes defended against ID-theft attacks, reply attacks, undetectable on-line password guessing attacks, off-line password guessing attacks, user impersonation attack, server counterfeit attack
[...] Read more.
In 2010, Yeh et al. proposed two robust remote user authentication schemes using smart cards; their claims were such that their schemes defended against ID-theft attacks, reply attacks, undetectable on-line password guessing attacks, off-line password guessing attacks, user impersonation attack, server counterfeit attack and man-in-the-middle attack. In this paper, we show that Yeh et al.’s schemes are still vulnerable to ID-theft attack, off-line password guessing attacks, undetectable on-line password guessing attacks and user impersonation attack. Notably, problems remain in situations where the user lost a smart card or the malicious legal user. To remedy these flaws, this paper proposes an improvement on Yeh et al.’s remote user authentication schemes using smart cards. Full article
Figures

Figure 1

Open AccessArticle
Performance Evaluation of Discrete Event Systems with GPenSIM
Computers 2018, 7(1), 8; doi:10.3390/computers7010008 -
Abstract
Petri nets are a useful tool for the modeling and performance evaluation of discrete event systems. Literature reveals that the Petri Net models of real-world discrete event systems are most frequently event graphs (a subclass of Petri nets). Literature also reveals that there
[...] Read more.
Petri nets are a useful tool for the modeling and performance evaluation of discrete event systems. Literature reveals that the Petri Net models of real-world discrete event systems are most frequently event graphs (a subclass of Petri nets). Literature also reveals that there are some simple methods for the performance evaluation of event graphs. The general-purpose Petri Net simulator (GPenSIM) is a new simulator that runs on the MATLAB platform. GPenSIM provides a Petri net language, with which Petri net classes and extensions can be developed. GPenSIM also provides functions for performance analysis. Since real-world discrete event systems usually possess a large number of resources, the Petri net models of these systems tend to become huge. Activity-Oriented Petri Nets (AOPN) is an approach that reduces the size of the Petri nets. In addition to the simulator functions, GPenSIM also realizes the AOPN approach on the MATLAB platform. Thus, AOPN is an integral part of GPenSIM. As a running example, a flexible manufacturing system is firstly modeled as an event graph, and then the size of the model is reduced with the AOPN approach. The advantages of GPenSIM and AOPN are discussed in this paper. Full article
Figures

Figure 1

Open AccessArticle
Self-Monitoring of Emotions and Mood Using a Tangible Approach
Computers 2018, 7(1), 7; doi:10.3390/computers7010007 -
Abstract
Nowadays Personal Informatics (PI) devices are used for sensing and saving personal data, everywhere and at any time, helping people improve their lives by highlighting areas of good and bad performances and providing a general awareness of different levels of conduct. However, not
[...] Read more.
Nowadays Personal Informatics (PI) devices are used for sensing and saving personal data, everywhere and at any time, helping people improve their lives by highlighting areas of good and bad performances and providing a general awareness of different levels of conduct. However, not all these data are suitable to be automatically collected. This is especially true for emotions and mood. Moreover, users without experience in self-tracking may have a misperception of PI applications’ limits and potentialities. We believe that current PI tools are not designed with enough understanding of such users’ needs, desires, and problems they may encounter in their everyday lives. We designed and prototype the Mood TUI (Tangible User Interface), a PI tool that supports the self-reporting of mood data using a tangible interface. The platform is able to gather six different mood states and it was tested through several participatory design sessions in a secondary/high school. The solution proposed allows gathering mood values in an amusing, simple, and appealing way. Users appreciated the prototypes, suggesting several possible improvements as well as ideas on how to use the prototype in similar or totally different contexts, and giving us hints for future research. Full article
Figures

Figure 1