There is a strong trend towards networked cyber-physical systems that bridge the virtual world of networking and computing and the real world. One of the major characteristics of cyber-physical systems is the tight integration of computation (more specifically, software) and physical objects through networks. In a typical cyber-physical system, various components are networked to sense, monitor and control the physical world. Cyber-physical systems promise to improve the quality of our daily lives by enabling innovative services and applications. To realize the potential of cyber-physical applications, high-confidence networks and software become essential.

In this ComSIS special issue on “Cyber-Physical Networks and Software”, we are focused on the latest achievements that address key issues and topics related to design and applications of cyber-physical networks and software. A collection of 19 papers is selected from 79 open submissions through a rigorous peer-review process. The selection provides a glimpse of the state-of-the-art research in the field.

In the paper “An Improved Node Localization Algorithm Based on DV-Hop for Wireless Sensor Networks”, Qian et al. propose a novel localization algorithm called NDV-Hop_Bon based on the popular DV-Hop localization algorithm for wireless sensor networks (WSNs). The proposed algorithm selects the reference nodes of a certain number to position the unknown nodes based on different environments. The simulation results show that the positioning accuracy is improved.

The paper “Energy-Efficient Opportunistic Localization with Indoor Wireless Sensor Networks” proposes an Energy-Efficient Opportunistic Localization (EEOL) scheme to satisfy the requirements of both positional accuracy and power consumption. The idea of opportunistic wake-up probability is exploited to wake up an appropriate numbers of sensor nodes, while ensuring the high positional accuracy. Through utilizing this method, the number of active sensors in the sensing range of the user is decreased, and the power consumption is significantly reduced.

In the paper “An Energy Efficient and Load Balancing Routing Algorithm for Wireless Sensor Networks”, Wang et al. propose a Ring-based Energy Aware Routing (REAR) algorithm for WSNs which can achieve both energy balancing and energy efficiency for all sensor nodes. The algorithm considers not only the hop number and distance but also the residual energy of the next hop node during the routing process.

The purpose of the paper “A Redistribution Method to Conserve Data in Isolated Energy-harvesting Sensor Networks” is to design a solution for fair data storage under space and energy limitation only based on local information. The authors propose a heuristic Distributed Energy-aware Data Conservation method (DEDC), which considers following two issues: i) where to store data with respect to energy and space storage, and ii) how to prioritize the transmission of important data.

In the paper “A Packet Buffer Evaluation Method Exploiting Queueing Theory for Wireless Sensor Networks”, Qiu et al. present a new evaluation method for packet buffer capacity of wireless sensor nodes using queueing network model, whose packet buffer capacity is analyzed for each type node, when it is in the best working condition. The authors establish an M/M/1/N-type queueing network model with holding nodes for WSNs and design approximate iterative algorithms.

In the paper “On the Efficiency of Cluster-based Approaches for Motion Detection using Body Sensor Networks”, Lan et al. first discuss the efficiency of cluster-based approaches for saving energy, and then propose a novel cluster head selection algorithm to maximize the lifetime of a body sensor network for motion detection.

In the paper “Optimization of Multiple Gateway Deployment for Underwater Acoustic Sensor Networks” by Nie et al, the deployment of surface gateways in underwater acoustic sensor networks is studied by considering the acoustic characteristics. The authors propose an optimization method of surface gateways deployment dynamically based on a genetic algorithm, design a novel transmission mechanism – simultaneous transmission, and realize two efficient routing algorithms that achieve minimal delay and payload balance among sensor nodes.

In the paper “A Distributed Power Management Design Based on MOST Networks”, a distributed power management solution is designed for MOST (Media Oriented Systems Transport) networks, in which the slave nodes can sleep independently and the master node manages the network state, and new wake-up mechanisms in the sleep state are proposed.

Liu et al. present an energy-efficient localization strategy for smartphone applications in the paper “An Energy-Efficient Localization Strategy for Smartphones”. On one hand, the strategy can dynamically estimate the next localization time point to avoid unnecessary localization operations. On the other hand, it can also automatically select the energy-optimal localization method. The authors evaluate the strategy through a series of simulations.

Based on a complex network approach, a contact network model with scale-free property is built in the paper “Modeling Disease Spreading on Complex Networks” by Kong et al. By analyzing the fact data of H1N1 influenza provided by the Beijing Health Bureau, a contact tracing mechanism is used to research H1N1 virus transmission dynamics with this model. Furthermore, the contact tracing coefficient and random checking coefficient are studied to analyze their impact on the peak value of new infections and cumulative number of infections.

In the paper “An Improved Spectral Clustering Algorithm Based on Local Neighbors in Kernel Space”, a novel spectral clustering method is proposed based on local neighborhood in kernel space (SC-LNK), which assumes that each data point can be linearly reconstructed from its neighbors. The SC-LNK algorithm tries to project the data to a feature space by the Mercer kernel, and then learn a sparse matrix using linear reconstruction as the similarity graph for spectral clustering.

In the paper “A Novel Capacity and Trust Based Service Selection Mechanism for Collaborative Decision Making in CPS”, Zhang et al. propose a novel capacity and trust computation based cyber-physical systems (CPS) service selection mechanism in intelligent and automatic manners. The mechanism comprises three phases, including capacity evaluation, trust computation and negotiation selection.

In the paper “Privacy Preserving in Ubiquitous Computing: Classification & Hierarchy”, Ma et al. present a privacy-preserving architecture utilizing the classification of personal information and hierarchy of services, which are derived from the concept of Class in the Object Orient Programming. In a sense, the authors strike a balance between two goals of Ubiquitous Computing: interaction and privacy preserving.

In the paper “TRM-IoT: A Trust Management Model Based on Fuzzy Reputation for Internet of Things”, Chen et al. present a trust and reputation model TRM-IoT to enforce the cooperation between things in a network of IoT/CPS based on their behaviors. The accuracy, robustness and lightness of the proposed model is validated through a wide set of simulations.

In the paper “A Reusable Agent Design Pattern with Flexibility and Extensibility”, Zhang et al. introduce a novel design for agent-based systems, which is able to provide an efficient design pattern for improving the reusability, extensibility and flexibility of agent design. The novel agent capability design offers an open and flexible structure, and implements several practical algorithms that can improve the system performance.

In the paper “Quantitative Analysis for Symbolic Heap Bounds of CPS Software”, Li et al. present a framework for statically analyzing symbolic heap bounds of CPS software. A novel list abstraction method is also proposed, which maintains precise shape properties and quantitative properties. The authors build a prototype tool that can analyze the heap bounds automatically.

The development of automotive CPS software needs to consider not only functional requirements, but also non-functional requirements and the interaction with physical environments. In the paper “A Model-Based Software Development Method for Automotive Cyber-Physical Systems”, a model-based software development method for automotive CPS (MoBDAC) is presented. The authors illustrate the development workflow of MoBDAC by an example of a power window development.

The paper “Velocity Adaptation for Synchronizing a Mobile Agent Network” investigates the problem of synchronizing a mobile agent network by means of a velocity adaptation strategy, where each agent is assigned different moving velocities to establish a time-varying network topology, and the velocity of each agent develops adaptively according to the local property between itself and its neighbors.

Li et al. present a REST-style architecture for CPS in the paper “A Case Study on REST-Style Architecture for Cyber-Physical Systems: Restful Smart Gateway”. The authors propose a path towards solving requirements of CPS architecture through Restful principles. A prototyping system called the restful smart gateway is built, which seamlessly integrates conceptual and physical resources into the Web.

It has been a great pleasure to run this special issue, which reveals important research results in the field of Cyber-Physical Networks and Software. I would like to thank Prof. Mirjana Ivanović, Editor-in-Chief of ComSIS, and other staff in the Editorial Office for giving me the opportunity to organize this special issue and for their great help in the organization of this issue. I thank all authors for their submissions and all reviewers for their diligent work in evaluating these submissions. I sincerely hope that you enjoy reading these distinguished papers.

Guest Editor
Feng Xia
School of Software, Dalian University of Technology
Dalian 116620, China

Mirjana Ivanović