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Special Issue "Real-Time and Cyber-Physical Systems"

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Sensor Networks".

Deadline for manuscript submissions: closed (30 June 2016)

Special Issue Editor

Guest Editor
Prof. Dr. Albert M. K. Cheng

Department of Computer Science University of Houston Houston, TX77004, USA
Website | E-Mail
Interests: real-time and embedded systems, functional reactive programming, real-time virtualization, cyber-physical systems, power-aware computing, formal verification, real-time logic, rule-based systems

Special Issue Information

Dear Colleagues,

A cyber-physical system (CPS) is a tightly coupled integration and coordination of computing elements, communication components, and physical resources. A multitude of wired and/or wireless communication/sensor networks connect these computing elements and physical resources. It is not sufficient to study each of the following in isolation since a CPS is not their union but their intersection: embedded computers, control theory, sensor and communication networks, physical resources, decision theory, data fusion, and knowledge discovery. Their joint dynamics must be studied together and this is what set this emerging discipline apart from these individually established fields. Before deploying a CPS, a formal modeling, analysis, and verification must be performed on the entire system as well as its components to ensure the CPS's safety, performance, and resilience. This special issue is devoted to the latest research in CPS and solicits papers in the following (but not limited to) topics:

  • Cyber-Physical Systems
  • Real-Time and Embedded Systems
  • Real-Time Virtualization
  • Design Space Exploration and Synthesis
  • Control and Optimization
  • Automatic Optimization of Specifications and in Compilers, and Code Generators
  • Timing and Performance Analysis
  • Functional reactive systems
  • Model-based Testing
  • Correct-by-Construction
  • Requirements Modeling and Analysis
  • Model-driven Engineering
  • Application of Formal Methods in the design and validation of embedded systems
  • Safety Analysis
  • Fault Tolerance and Resilience
  • Sensor Networks
  • Code Generator Verification
  • Machine Learning
  • Data Fusion and Mining
  • Security

Prof. Dr. Albert M. K. Cheng
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (7 papers)

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Research

Open AccessArticle Markov Task Network: A Framework for Service Composition under Uncertainty in Cyber-Physical Systems
Sensors 2016, 16(9), 1542; doi:10.3390/s16091542
Received: 21 June 2016 / Revised: 9 September 2016 / Accepted: 13 September 2016 / Published: 21 September 2016
Cited by 1 | PDF Full-text (1906 KB) | HTML Full-text | XML Full-text
Abstract
In novel collaborative systems, cooperative entities collaborate services to achieve local and global objectives. With the growing pervasiveness of cyber-physical systems, however, such collaboration is hampered by differences in the operations of the cyber and physical objects, and the need for the dynamic
[...] Read more.
In novel collaborative systems, cooperative entities collaborate services to achieve local and global objectives. With the growing pervasiveness of cyber-physical systems, however, such collaboration is hampered by differences in the operations of the cyber and physical objects, and the need for the dynamic formation of collaborative functionality given high-level system goals has become practical. In this paper, we propose a cross-layer automation and management model for cyber-physical systems. This models the dynamic formation of collaborative services pursuing laid-down system goals as an ontology-oriented hierarchical task network. Ontological intelligence provides the semantic technology of this model, and through semantic reasoning, primitive tasks can be dynamically composed from high-level system goals. In dealing with uncertainty, we further propose a novel bridge between hierarchical task networks and Markov logic networks, called the Markov task network. This leverages the efficient inference algorithms of Markov logic networks to reduce both computational and inferential loads in task decomposition. From the results of our experiments, high-precision service composition under uncertainty can be achieved using this approach. Full article
(This article belongs to the Special Issue Real-Time and Cyber-Physical Systems)
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Open AccessArticle Mixed Criticality Scheduling for Industrial Wireless Sensor Networks
Sensors 2016, 16(9), 1376; doi:10.3390/s16091376
Received: 2 June 2016 / Revised: 18 August 2016 / Accepted: 23 August 2016 / Published: 29 August 2016
Cited by 2 | PDF Full-text (3377 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks (WSNs) have been widely used in industrial systems. Their real-time performance and reliability are fundamental to industrial production. Many works have studied the two aspects, but only focus on single criticality WSNs. Mixed criticality requirements exist in many advanced applications
[...] Read more.
Wireless sensor networks (WSNs) have been widely used in industrial systems. Their real-time performance and reliability are fundamental to industrial production. Many works have studied the two aspects, but only focus on single criticality WSNs. Mixed criticality requirements exist in many advanced applications in which different data flows have different levels of importance (or criticality). In this paper, first, we propose a scheduling algorithm, which guarantees the real-time performance and reliability requirements of data flows with different levels of criticality. The algorithm supports centralized optimization and adaptive adjustment. It is able to improve both the scheduling performance and flexibility. Then, we provide the schedulability test through rigorous theoretical analysis. We conduct extensive simulations, and the results demonstrate that the proposed scheduling algorithm and analysis significantly outperform existing ones. Full article
(This article belongs to the Special Issue Real-Time and Cyber-Physical Systems)
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Open AccessArticle Data-Aware Retrodiction for Asynchronous Harmonic Measurement in a Cyber-Physical Energy System
Sensors 2016, 16(8), 1316; doi:10.3390/s16081316
Received: 29 March 2016 / Revised: 4 August 2016 / Accepted: 12 August 2016 / Published: 18 August 2016
PDF Full-text (1400 KB) | HTML Full-text | XML Full-text
Abstract
Cyber-physical energy systems provide a networked solution for safety, reliability and efficiency problems in smart grids. On the demand side, the secure and trustworthy energy supply requires real-time supervising and online power quality assessing. Harmonics measurement is necessary in power quality evaluation. However,
[...] Read more.
Cyber-physical energy systems provide a networked solution for safety, reliability and efficiency problems in smart grids. On the demand side, the secure and trustworthy energy supply requires real-time supervising and online power quality assessing. Harmonics measurement is necessary in power quality evaluation. However, under the large-scale distributed metering architecture, harmonic measurement faces the out-of-sequence measurement (OOSM) problem, which is the result of latencies in sensing or the communication process and brings deviations in data fusion. This paper depicts a distributed measurement network for large-scale asynchronous harmonic analysis and exploits a nonlinear autoregressive model with exogenous inputs (NARX) network to reorder the out-of-sequence measuring data. The NARX network gets the characteristics of the electrical harmonics from practical data rather than the kinematic equations. Thus, the data-aware network approximates the behavior of the practical electrical parameter with real-time data and improves the retrodiction accuracy. Theoretical analysis demonstrates that the data-aware method maintains a reasonable consumption of computing resources. Experiments on a practical testbed of a cyber-physical system are implemented, and harmonic measurement and analysis accuracy are adopted to evaluate the measuring mechanism under a distributed metering network. Results demonstrate an improvement of the harmonics analysis precision and validate the asynchronous measuring method in cyber-physical energy systems. Full article
(This article belongs to the Special Issue Real-Time and Cyber-Physical Systems)
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Open AccessArticle Computation and Communication Evaluation of an Authentication Mechanism for Time-Triggered Networked Control Systems
Sensors 2016, 16(8), 1166; doi:10.3390/s16081166
Received: 2 May 2016 / Revised: 12 July 2016 / Accepted: 15 July 2016 / Published: 25 July 2016
PDF Full-text (791 KB) | HTML Full-text | XML Full-text
Abstract
In modern networked control applications, confidentiality and integrity are important features to address in order to prevent against attacks. Moreover, network control systems are a fundamental part of the communication components of current cyber-physical systems (e.g., automotive communications). Many networked control systems employ
[...] Read more.
In modern networked control applications, confidentiality and integrity are important features to address in order to prevent against attacks. Moreover, network control systems are a fundamental part of the communication components of current cyber-physical systems (e.g., automotive communications). Many networked control systems employ Time-Triggered (TT) architectures that provide mechanisms enabling the exchange of precise and synchronous messages. TT systems have computation and communication constraints, and with the aim to enable secure communications in the network, it is important to evaluate the computational and communication overhead of implementing secure communication mechanisms. This paper presents a comprehensive analysis and evaluation of the effects of adding a Hash-based Message Authentication (HMAC) to TT networked control systems. The contributions of the paper include (1) the analysis and experimental validation of the communication overhead, as well as a scalability analysis that utilizes the experimental result for both wired and wireless platforms and (2) an experimental evaluation of the computational overhead of HMAC based on a kernel-level Linux implementation. An automotive application is used as an example, and the results show that it is feasible to implement a secure communication mechanism without interfering with the existing automotive controller execution times. The methods and results of the paper can be used for evaluating the performance impact of security mechanisms and, thus, for the design of secure wired and wireless TT networked control systems. Full article
(This article belongs to the Special Issue Real-Time and Cyber-Physical Systems)
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Open AccessArticle Resolution-Enhanced Harmonic and Interharmonic Measurement for Power Quality Analysis in Cyber-Physical Energy System
Sensors 2016, 16(7), 946; doi:10.3390/s16070946
Received: 29 March 2016 / Revised: 12 June 2016 / Accepted: 16 June 2016 / Published: 27 June 2016
PDF Full-text (566 KB) | HTML Full-text | XML Full-text
Abstract
Power quality analysis issues, especially the measurement of harmonic and interharmonic in cyber-physical energy systems, are addressed in this paper. As new situations are introduced to the power system, the impact of electric vehicles, distributed generation and renewable energy has introduced extra demands
[...] Read more.
Power quality analysis issues, especially the measurement of harmonic and interharmonic in cyber-physical energy systems, are addressed in this paper. As new situations are introduced to the power system, the impact of electric vehicles, distributed generation and renewable energy has introduced extra demands to distributed sensors, waveform-level information and power quality data analytics. Harmonics and interharmonics, as the most significant disturbances, require carefully designed detection methods for an accurate measurement of electric loads whose information is crucial to subsequent analyzing and control. This paper gives a detailed description of the power quality analysis framework in networked environment and presents a fast and resolution-enhanced method for harmonic and interharmonic measurement. The proposed method first extracts harmonic and interharmonic components efficiently using the single-channel version of Robust Independent Component Analysis (RobustICA), then estimates the high-resolution frequency from three discrete Fourier transform (DFT) samples with little additional computation, and finally computes the amplitudes and phases with the adaptive linear neuron network. The experiments show that the proposed method is time-efficient and leads to a better accuracy of the simulated and experimental signals in the presence of noise and fundamental frequency deviation, thus providing a deeper insight into the (inter)harmonic sources or even the whole system. Full article
(This article belongs to the Special Issue Real-Time and Cyber-Physical Systems)
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Open AccessArticle Real-Time Monitoring System for a Utility-Scale Photovoltaic Power Plant
Sensors 2016, 16(6), 770; doi:10.3390/s16060770
Received: 8 April 2016 / Revised: 18 May 2016 / Accepted: 24 May 2016 / Published: 26 May 2016
Cited by 6 | PDF Full-text (8694 KB) | HTML Full-text | XML Full-text
Abstract
There is, at present, considerable interest in the storage and dispatchability of photovoltaic (PV) energy, together with the need to manage power flows in real-time. This paper presents a new system, PV-on time, which has been developed to supervise the operating mode
[...] Read more.
There is, at present, considerable interest in the storage and dispatchability of photovoltaic (PV) energy, together with the need to manage power flows in real-time. This paper presents a new system, PV-on time, which has been developed to supervise the operating mode of a Grid-Connected Utility-Scale PV Power Plant in order to ensure the reliability and continuity of its supply. This system presents an architecture of acquisition devices, including wireless sensors distributed around the plant, which measure the required information. It is also equipped with a high-precision protocol for synchronizing all data acquisition equipment, something that is necessary for correctly establishing relationships among events in the plant. Moreover, a system for monitoring and supervising all of the distributed devices, as well as for the real-time treatment of all the registered information, is presented. Performances were analyzed in a 400 kW transformation center belonging to a 6.1 MW Utility-Scale PV Power Plant. In addition to monitoring the performance of all of the PV plant’s components and detecting any failures or deviations in production, this system enables users to control the power quality of the signal injected and the influence of the installation on the distribution grid. Full article
(This article belongs to the Special Issue Real-Time and Cyber-Physical Systems)
Open AccessArticle A PetriNet-Based Approach for Supporting Traceability in Cyber-Physical Manufacturing Systems
Sensors 2016, 16(3), 382; doi:10.3390/s16030382
Received: 5 February 2016 / Revised: 6 March 2016 / Accepted: 14 March 2016 / Published: 17 March 2016
Cited by 3 | PDF Full-text (4441 KB) | HTML Full-text | XML Full-text
Abstract
With the growing popularity of complex dynamic activities in manufacturing processes, traceability of the entire life of every product has drawn significant attention especially for food, clinical materials, and similar items. This paper studies the traceability issue in cyber-physical manufacturing systems from a
[...] Read more.
With the growing popularity of complex dynamic activities in manufacturing processes, traceability of the entire life of every product has drawn significant attention especially for food, clinical materials, and similar items. This paper studies the traceability issue in cyber-physical manufacturing systems from a theoretical viewpoint. Petri net models are generalized for formulating dynamic manufacturing processes, based on which a detailed approach for enabling traceability analysis is presented. Models as well as algorithms are carefully designed, which can trace back the lifecycle of a possibly contaminated item. A practical prototype system for supporting traceability is designed, and a real-life case study of a quality control system for bee products is presented to validate the effectiveness of the approach. Full article
(This article belongs to the Special Issue Real-Time and Cyber-Physical Systems)

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