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George K. Adam is an associate professor at the University of Thessaly, Greece. His research interests include computer systems design and applications, computer architectures, operating systems, microcomputer-based control, control software, mechatronics. Dr. Adam is a member of ACM, IEEE Robotics and Automation, IEEE Computer and IEEE Control Systems Societies.
This work investigates the real-time performance of Linux kernels and distributions with a PREEMPT_RT real-time patch on ARM-based embedded devices. Experimental measurements, which are mainly based on heuristic methods, provide novel insights into Linux real-time performance on ARM-based embedded devices (e.g., BeagleBoard and RaspberryPi). Evaluations of the Linux real-time performance are based on specific real-time software measurement modules, developed for this purpose, and the use of a standard benchmark tool, cyclictest. Software modules were designed upon the introduction of a new response task model, an innovative aspect of this work. Measurements include the latency of response tasks at user and kernel space, the response on the execution of periodic tasks, the maximum sustained frequency and general latency performance metrics. The results show that in such systems the PREEMPT_RT patch provides more improved real-time performance than the default Linux kernels. The latencies and particularly the worst-case latencies are reduced with real-time support, thus making such devices running Linux with PREEMPT_RT more appropriate for use in time-sensitive embedded control systems and applications. Furthermore, the proposed performance measurements approach and evaluation methodology could be applied and deployed on other Linux-based real-time platforms.
George Adam; Nikos Petrellis; Lambros Doulos. Performance Assessment of Linux Kernels with PREEMPT_RT on ARM-Based Embedded Devices. Electronics 2021, 10, 1331 .
AMA StyleGeorge Adam, Nikos Petrellis, Lambros Doulos. Performance Assessment of Linux Kernels with PREEMPT_RT on ARM-Based Embedded Devices. Electronics. 2021; 10 (11):1331.
Chicago/Turabian StyleGeorge Adam; Nikos Petrellis; Lambros Doulos. 2021. "Performance Assessment of Linux Kernels with PREEMPT_RT on ARM-Based Embedded Devices." Electronics 10, no. 11: 1331.
This research performs real-time measurements of Linux kernels with real-time support provided by the PREEMPT_RT patch on embedded development devices such as BeagleBoard and Raspberry Pi. The experimental measurements of the Linux real-time performance on these devices are based on real-time software modules developed specifically for the purposes of this research. Taking in consideration the constraints of the specific hardware platforms under investigation, new measurements software was developed. The measurement algorithms are designed upon response and periodic task models. Measurements investigate latencies of real-time applications at user and kernel space. An outcome of this research is that the proposed performance measurements approach and evaluation methodology could be applied and deployed on other Linux-based boards and platforms. Furthermore, the results demonstrate that the PREEMPT_RT patch overall improves the Linux kernel real-time performance compared to the standard one. The reduced worst-case latencies on such devices running Linux with real-time support could make them potentially more suitable for real-time applications as long as a latency value of about 160 μs, as an upper bound, is an acceptable safety margin.
George Adam. Real-Time Performance and Response Latency Measurements of Linux Kernels on Single-Board Computers. Computers 2021, 10, 64 .
AMA StyleGeorge Adam. Real-Time Performance and Response Latency Measurements of Linux Kernels on Single-Board Computers. Computers. 2021; 10 (5):64.
Chicago/Turabian StyleGeorge Adam. 2021. "Real-Time Performance and Response Latency Measurements of Linux Kernels on Single-Board Computers." Computers 10, no. 5: 64.
Remote symptom tracking is critical for the prevention of Covid-19 spread. The qualified medical staff working in the call centers of primary health care units have to take critical decisions often based on vague information about the patient condition. The congestion and the medical protocols that are constantly changing often lead to incorrect decisions. The proposed platform allows the remote assessment of symptoms and can be useful for patients, health institutes and researchers. It consists of mobile desktop applications and medical sensors connected to cloud infrastructure. The unique features offered by the proposed solution are: (a) dynamic adaptation of Medical Protocols (MP) is supported (for the definition of alert rules, sensor sampling strategy and questionnaire structure) covering different medical cases (pre- or post-hospitalization, vulnerable population, etc.), (b) anonymous medical data can be statistically processed in the context of the research about an infection such as Covid-19, (c) reliable diagnosis is supported since several factors are taken into consideration, (d) the platform can be used to drastically reduce the congestion in various healthcare units. For the demonstration of (b), new classification methods based on similarity metrics have been tested for cough sound classification with an accuracy in the order of 90%.
Nikos Petrellis; George Adam. Symptom Tracking and Experimentation Platform for Covid-19 or Similar Infections. Computers 2021, 10, 22 .
AMA StyleNikos Petrellis, George Adam. Symptom Tracking and Experimentation Platform for Covid-19 or Similar Infections. Computers. 2021; 10 (2):22.
Chicago/Turabian StyleNikos Petrellis; George Adam. 2021. "Symptom Tracking and Experimentation Platform for Covid-19 or Similar Infections." Computers 10, no. 2: 22.
George Adam. Graph homomorphisms and qualitative software system analysis. 2021, 1 .
AMA StyleGeorge Adam. Graph homomorphisms and qualitative software system analysis. . 2021; ():1.
Chicago/Turabian StyleGeorge Adam. 2021. "Graph homomorphisms and qualitative software system analysis." , no. : 1.
George Adam. Modelling and simulation with Arena of a mechatronics system for hydraulic tubes construction. Modelling and simulation with Arena of a mechatronics system for hydraulic tubes construction 2021, 1 .
AMA StyleGeorge Adam. Modelling and simulation with Arena of a mechatronics system for hydraulic tubes construction. Modelling and simulation with Arena of a mechatronics system for hydraulic tubes construction. 2021; ():1.
Chicago/Turabian StyleGeorge Adam. 2021. "Modelling and simulation with Arena of a mechatronics system for hydraulic tubes construction." Modelling and simulation with Arena of a mechatronics system for hydraulic tubes construction , no. : 1.
George Adam. Geographical image analysis and information retrieval using GisTool. Geographical image analysis and information retrieval using GisTool 2021, 1 .
AMA StyleGeorge Adam. Geographical image analysis and information retrieval using GisTool. Geographical image analysis and information retrieval using GisTool. 2021; ():1.
Chicago/Turabian StyleGeorge Adam. 2021. "Geographical image analysis and information retrieval using GisTool." Geographical image analysis and information retrieval using GisTool , no. : 1.
George Adam. Programming and control of an industrial robotic system. Programming and control of an industrial robotic system 2021, 1 .
AMA StyleGeorge Adam. Programming and control of an industrial robotic system. Programming and control of an industrial robotic system. 2021; ():1.
Chicago/Turabian StyleGeorge Adam. 2021. "Programming and control of an industrial robotic system." Programming and control of an industrial robotic system , no. : 1.
George Adam. Qualitative methods in control of industrial production units. 2021, 1 .
AMA StyleGeorge Adam. Qualitative methods in control of industrial production units. . 2021; ():1.
Chicago/Turabian StyleGeorge Adam. 2021. "Qualitative methods in control of industrial production units." , no. : 1.
George Adam. GisTool: An integrated environment for GIS data management. GisTool: An integrated environment for GIS data management 2021, 1 .
AMA StyleGeorge Adam. GisTool: An integrated environment for GIS data management. GisTool: An integrated environment for GIS data management. 2021; ():1.
Chicago/Turabian StyleGeorge Adam. 2021. "GisTool: An integrated environment for GIS data management." GisTool: An integrated environment for GIS data management , no. : 1.
The progress of embedded control systems in the last several years has made possible the realization of highly-effective controllers in many domains. It is essential for such systems to provide effective performance at an affordable cost. Furthermore, real-time embedded control systems must have low energy consumption, as well as be reliable and timely. This research investigates primarily the feasibility of implementing an embedded real-time control system, based on a low-cost, commercially off-the-shelf (COTS) microcontroller platform. It explores real-time issues, such as the reliability and timely response, of such a system implementation. This work presents the development and performance evaluation of a novel real-time control architecture, based upon a BeagleBoard microcontroller, and applied into the PWM (pulse width modulation) control of a three-phase induction motor in a suction pump. The approach followed makes minimal use of general-purpose hardware (BeagleBone Black microcontroller board) and open-source software components (including Linux Operating System with PREEMPT_RT real-time support) for building a reliable real-time control system. The applicability of the proposed control system architecture is validated and evaluated in a real case study in manufacturing. The results provide sufficient evidence of the efficiency and reliability of the proposed approach into the development of a real-time control system based upon COTS components.
George K. Adam; Nikos Petrellis; Panagiotis A. Kontaxis; Tilemachos Stylianos. COTS-Based Real-Time System Development: An Effective Application in Pump Motor Control. Computers 2020, 9, 97 .
AMA StyleGeorge K. Adam, Nikos Petrellis, Panagiotis A. Kontaxis, Tilemachos Stylianos. COTS-Based Real-Time System Development: An Effective Application in Pump Motor Control. Computers. 2020; 9 (4):97.
Chicago/Turabian StyleGeorge K. Adam; Nikos Petrellis; Panagiotis A. Kontaxis; Tilemachos Stylianos. 2020. "COTS-Based Real-Time System Development: An Effective Application in Pump Motor Control." Computers 9, no. 4: 97.
A Trajectory Data Warehouse is a central repository of large amount of data focusing on moving objects, which have been collected and integrated from multiple sources with spatial and temporal dimensions as the main metrics of analysis. By adding semantic-related contextual information, it is converted to a Semantic Trajectory Data Warehouse. It transforms raw trajectories to valuable information that can be utilized for decision-making purposes in ubiquitous applications. Human recourses management is a domain that may benefit significantly from semantic trajectory data warehouses. In particular, employees working shifts can be considered as trajectories. In this work, standard data warehousing tools are used to store data about nursing personnel shifts as trajectories of moving persons. The conceptual and logical modelling of the semantic trajectory data warehouse is developed. The objective is the observation, management and scheduling of nurses’ shifts data by the computation of OLAP operations over them. A prototype implementation has also been realized to illustrate the functionality of the proposed model. The produced results prove the efficiency in improving nursing productivity.
Georgia Garani; George K. Adam. A semantic trajectory data warehouse for improving nursing productivity. Health Information Science and Systems 2020, 8, 1 -13.
AMA StyleGeorgia Garani, George K. Adam. A semantic trajectory data warehouse for improving nursing productivity. Health Information Science and Systems. 2020; 8 (1):1-13.
Chicago/Turabian StyleGeorgia Garani; George K. Adam. 2020. "A semantic trajectory data warehouse for improving nursing productivity." Health Information Science and Systems 8, no. 1: 1-13.
The challenge of keeping the development and implementation of real-time control systems reliable and efficient and at the same time, low-cost and low-energy, is getting harder. This is because system designers and developers are faced with the dependability, inflexibility and often high-cost of specialized or custom-built hardware and software components. This research attempts to tackle issues such as the reliability and efficiency of real-time control systems and advance further the current state-of-the-art. For this purpose, a strong emphasis is placed on finding novel efficient solutions based on standardized and commercially available off-the-shelf hardware/software components. In this direction, this research applies credible and feasible methodologies (e.g., model-based design, component-based design, formal verification, real-time scheduling, prototyping, and validation) in an innovative enhanced way. As an important outcome, a versatile integrative design approach and architectural framework (VIDAF) is proposed, which supports the development and implementation of reliable real-time control systems and applications using commercial off-the-shelf (COTS) components. The feasibility and applicability of the proposed system’s architecture are evaluated and validated through a system application in embedded real-time control in manufacturing. The research outcomes are expected to have a positive impact on emerging areas such as the Industrial Internet of Things (IIoT).
George K. Adam; Nikos Petrellis; Georgia Garani; Tilemachos Stylianos. COTS-Based Architectural Framework for Reliable Real-Time Control Applications in Manufacturing. Applied Sciences 2020, 10, 3228 .
AMA StyleGeorge K. Adam, Nikos Petrellis, Georgia Garani, Tilemachos Stylianos. COTS-Based Architectural Framework for Reliable Real-Time Control Applications in Manufacturing. Applied Sciences. 2020; 10 (9):3228.
Chicago/Turabian StyleGeorge K. Adam; Nikos Petrellis; Georgia Garani; Tilemachos Stylianos. 2020. "COTS-Based Architectural Framework for Reliable Real-Time Control Applications in Manufacturing." Applied Sciences 10, no. 9: 3228.
Light emitting diodes (LEDs) as an efficient low-consumption lighting technology are being used increasingly in many applications. The move to LED lighting is also changing the way the lighting control systems are designed. Currently, most electronic ballasts and other digital lighting devices implement the Digital Addressable Lighting Interface (DALI) standard. This paper presents a low-cost, low-power effective DALI LED driver controller, based on open-source Raspberry Pi3 microcontroller prototyping platform. The control software is developed as a Linux kernel module under UBUNTU 18.04.2 LTS patched with PREEMPT_RT (Preemptive Real-time) for real-time processing. This dynamically loaded kernel module performs all the processing, communication and control operations of the Raspberry Pi3-based DALI controller with the DALI LED driver and LED luminaire. Software applications written in C and Python were developed for performance testing purposes. The experimental results showed that the proposed system could efficiently and effectively manage DALI LED drivers and perform lighting operations (e.g. dimming). The system can be used for a variety of purposes from personal lighting control needs and experimental research in control of electronic ballasts and other control gears, devices and sensors, to advanced requirements in professional buildings, including energy management, lighting maintenance and usage.
George Adam. DALI LED Driver Control System for Lighting Operations Based on Raspberry Pi and Kernel Modules. Electronics 2019, 8, 1021 .
AMA StyleGeorge Adam. DALI LED Driver Control System for Lighting Operations Based on Raspberry Pi and Kernel Modules. Electronics. 2019; 8 (9):1021.
Chicago/Turabian StyleGeorge Adam. 2019. "DALI LED Driver Control System for Lighting Operations Based on Raspberry Pi and Kernel Modules." Electronics 8, no. 9: 1021.
The protection of the environment is one of the main problems the mankind faces today. Recent advances in computer technology have assisted environmental studies towards this direction, in various scientific approaches. In this study, an attempt was undertaken on the integration of various environmental data (mainly agricultural) into databases with database management facilities and data analysis methods, using an interactive information system created for this purpose and called AgroModel. The aim was to provide a proper educational and friendly system for a more efficient integration and manipulation of huge environmental data in order to be used for educational and research purposes. Arising out of a need for a better organization and exploitation of environmental knowledge, an integrated interactive computer system for environmental (plant & animal) education and research purposes was developed and used efficiently in local area research cases. The system provides build-in tools as well as interfaces to software packages for mathematical and statistical analysis. Being in such an integrated environment, the researcher could undertake any type of statistical analysis from the simplest descriptive statistics to the most sophisticated statistical approaches for the derivation of important parameters for scientific and practical applications. The protection of the environment is one of the main problems the mankind faces today. Recent advances in computer technology have assisted environmental studies towards this direction, in various scientific approaches. In this study, an attempt was undertaken on the integration of various environmental data (mainly agricultural) into databases with database management facilities and data analysis methods, using an interactive information system created for this purpose and called AgroModel. The aim was to provide a proper educational and friendly system for a more efficient integration and manipulation of huge environmental data in order to be used for educational and research purposes. Arising out of a need for a better organization and exploitation of environmental knowledge, an integrated interactive computer system for environmental (plant & animal) education and research purposes was developed and used efficiently in local area research cases. The system provides build-in tools as well as interfaces to software packages for mathematical and statistical analysis. Being in such an integrated environment, the researcher could undertake any type of statistical analysis from the simplest descriptive statistics to the most sophisticated statistical approaches for the derivation of important parameters for scientific and practical applications. Arising out of a need for a better organization and exploitation of environmental knowledge, an integrated interactive computer system for environmental (plant & animal) education and research purposes was developed and used efficiently in local area research cases. The system provides build-in tools as well as interfaces to software packages for mathematical and statistical analysis. Being in such an integrated environment, the researcher could undertake any type of statistical analysis from the simplest descriptive statistics to the most sophisticated statistical approaches for the derivation of important parameters for scientific and practical applications.
Stergtios Tzortzios; George Adam; N Dalezios. Computer-based methods in environmental data organization and management. Biometrics & Biostatistics International Journal 2019, 8, 76 -79.
AMA StyleStergtios Tzortzios, George Adam, N Dalezios. Computer-based methods in environmental data organization and management. Biometrics & Biostatistics International Journal. 2019; 8 (3):76-79.
Chicago/Turabian StyleStergtios Tzortzios; George Adam; N Dalezios. 2019. "Computer-based methods in environmental data organization and management." Biometrics & Biostatistics International Journal 8, no. 3: 76-79.
Although with the advent of the LEDs the energy consumption in buildings can be reduced by 50%, there exists a potential for energy savings due to lighting controls. Moreover, lighting controls can ensure that the near zero energy requirements by EU can be achieved for near zero energy buildings (nZEBs). For this reason, more sophisticated lighting controls must be proposed in order to take full advantage of LEDs and their flexibility concerning dimming. This paper proposes the architecture of an embedded computer camera controller for monitoring and management of image data, which is applied in various control cases, and particularly in digitally controlled lighting devices. The proposed system deals with real-time monitoring and management of a GigE camera input. An in-house developed algorithm using MATLAB enables the identification of areas in luminance values. The embedded microcontroller is part of a complete lighting control system with an imaging sensor in order to measure and control the illumination of several working areas of a room. The power consumption of the proposed lighting system was measured and was compared with the power consumption of a typical photosensor. The functional performance and operation of the proposed camera control system architecture was evaluated based upon a BeagleBone Black microcontroller board.
George K. Adam; Panagiotis A. Kontaxis; Lambros T. Doulos; Evangelos-Nikolaos D. Madias; Constantinos A. Bouroussis; Frangiskos V. Topalis. Embedded Microcontroller with a CCD Camera as a Digital Lighting Control System. Electronics 2019, 8, 33 .
AMA StyleGeorge K. Adam, Panagiotis A. Kontaxis, Lambros T. Doulos, Evangelos-Nikolaos D. Madias, Constantinos A. Bouroussis, Frangiskos V. Topalis. Embedded Microcontroller with a CCD Camera as a Digital Lighting Control System. Electronics. 2019; 8 (1):33.
Chicago/Turabian StyleGeorge K. Adam; Panagiotis A. Kontaxis; Lambros T. Doulos; Evangelos-Nikolaos D. Madias; Constantinos A. Bouroussis; Frangiskos V. Topalis. 2019. "Embedded Microcontroller with a CCD Camera as a Digital Lighting Control System." Electronics 8, no. 1: 33.
Temporal data warehouses (TDWs) have been developed for the management of time-varying data in dimensions. This paper presents a new approach for the logical modelling of TDWs. The novel design is based on the integration of two schemata, the star schema and the snowflake schema, to the temporal starnest schema. Time in the temporal starnest schema is not treated as another dimension but as time attributes in every temporal dimension, i.e., dimension tables dependent on time. Time manipulation functions for the treatment of time attributes are provided in the query language. The temporal starnest schema proposed in this paper expresses naturally hierarchy levels by the clustering of data in nested tables, with resulting description of aggregation levels for a dimension in a natural way. The proposed extension is applied to a TDW for accident monitoring in crossroads where the expressive power of the model is exemplified with several temporal queries expressed in a suitable extension of SQL standard.
Georgia Garani; George Adam; Dimitrios Ventzas. Temporal data warehouse logical modelling. International Journal of Data Mining, Modelling and Management 2016, 8, 144 .
AMA StyleGeorgia Garani, George Adam, Dimitrios Ventzas. Temporal data warehouse logical modelling. International Journal of Data Mining, Modelling and Management. 2016; 8 (2):144.
Chicago/Turabian StyleGeorgia Garani; George Adam; Dimitrios Ventzas. 2016. "Temporal data warehouse logical modelling." International Journal of Data Mining, Modelling and Management 8, no. 2: 144.
Monotonic errors cause severe errors and are inherent in several A/D Converter (ADC) architectures. Moreover, several error correcting and ADC output processing methods require a monotonic behavior for a successful operation. Based on the features of asynchronous ADCs, an architecture for the elimination of monotonic errors is presented. This monotonic error correcting module is connected at the output of an ADC and does not require any modification in its internal circuits. It controls an output buffering stage that discards output codes with monotonic errors and this correcting procedure is triggered by changes in specific output bits of the ADC. Simulation results show an improvement by 8 dB or 25% maximum, in the signal-to-noise and distortion ratio (SNDR) of an 8-bit ADC if this monotonic error elimination method is used alone and a further improvement by 1–5 dB if it is combined with a post processing method developed by the authors. Similar improvement can also be achieved in several other architectures like Subrange or Folding ADCs that operate in relatively high oversampling ratio and suffer from monotonic errors with specific features.
N. Petrellis; George Adam; D. Ventzas. MONOTONIC ERROR ELIMINATION IN SUBRANGE A/D CONVERTERS. Journal of Circuits, Systems and Computers 2013, 22, 1 .
AMA StyleN. Petrellis, George Adam, D. Ventzas. MONOTONIC ERROR ELIMINATION IN SUBRANGE A/D CONVERTERS. Journal of Circuits, Systems and Computers. 2013; 22 (1):1.
Chicago/Turabian StyleN. Petrellis; George Adam; D. Ventzas. 2013. "MONOTONIC ERROR ELIMINATION IN SUBRANGE A/D CONVERTERS." Journal of Circuits, Systems and Computers 22, no. 1: 1.
Current Mirrors are widely used in current mode circuits like A/D Converters, current conveyors, filters etc. The most important features of a current mirror are its precision, its input and output, resistance and minimum voltage and its frequency response. Although several mirrors with extremely small current transfer error have been presented, this error is usually measured in the typical case. This error may significantly differ in real-time conditions depending on mismatches, process and temperature variations. Stimulated by the current reference generation required in an A/D Converter with novel binary tree architecture that has been recently presented, an appropriate current mirror architecture supported by real time calibration logic is described in this paper. This mirror can generate a high enough output current (up to 1 mA), with relatively low transfer error (<4%), in a descent frequency range of up to 1 GHz. It requires a 1–1.2 V voltage supply and dissipates a power that can be as low as 0.3 mW. The error is measured using mismatch and process variation Monte Carlo post-layout simulations in TSMC 90 nm process.
Nikos Petrellis; George Adam; Dimitrios Ventzas. A real-time self-calibrated current mirror for wide range current reference generation, signal reproduction and delaying. Microelectronics Journal 2011, 43, 225 -234.
AMA StyleNikos Petrellis, George Adam, Dimitrios Ventzas. A real-time self-calibrated current mirror for wide range current reference generation, signal reproduction and delaying. Microelectronics Journal. 2011; 43 (3):225-234.
Chicago/Turabian StyleNikos Petrellis; George Adam; Dimitrios Ventzas. 2011. "A real-time self-calibrated current mirror for wide range current reference generation, signal reproduction and delaying." Microelectronics Journal 43, no. 3: 225-234.
Nikos Petrellis; George Adam; Dimitrios Ventzas. A Two-Step Post Processing Method for ADC Output Compression and Linearity Improvement. Signal and Image Processing and Applications / 716: Artificial Intelligence and Soft Computing 2011, 1 .
AMA StyleNikos Petrellis, George Adam, Dimitrios Ventzas. A Two-Step Post Processing Method for ADC Output Compression and Linearity Improvement. Signal and Image Processing and Applications / 716: Artificial Intelligence and Soft Computing. 2011; ():1.
Chicago/Turabian StyleNikos Petrellis; George Adam; Dimitrios Ventzas. 2011. "A Two-Step Post Processing Method for ADC Output Compression and Linearity Improvement." Signal and Image Processing and Applications / 716: Artificial Intelligence and Soft Computing , no. : 1.
G. Garani∗; George Adam. QUALITATIVE MODELS IN THE DESIGN AND CONSTRUCTION OF AN AUTONOMOUS HYDRAULIC PRESS MACHINE. Control and Intelligent Systems 2009, 37, 1 .
AMA StyleG. Garani∗, George Adam. QUALITATIVE MODELS IN THE DESIGN AND CONSTRUCTION OF AN AUTONOMOUS HYDRAULIC PRESS MACHINE. Control and Intelligent Systems. 2009; 37 (1):1.
Chicago/Turabian StyleG. Garani∗; George Adam. 2009. "QUALITATIVE MODELS IN THE DESIGN AND CONSTRUCTION OF AN AUTONOMOUS HYDRAULIC PRESS MACHINE." Control and Intelligent Systems 37, no. 1: 1.