Dan Pescaru

Validation of static properties in unified modeling language models for cyber physical systems

Cyber physical systems (CPSs) can be found nowadays in various fields of activity. The increased interest for these systems as evidenced by the large number of applications led to complex research regarding the most suitable methods for design and development. A promising solution for specification, visualization, and documentation of CPSs uses the Object Management Group (OMG) unified modeling language (UML). UML models allow an intuitive approach for embedded systems design, helping end-users to specify the requirements. However, the UML models are represented in an informal language. Therefore, it is difficult to verify the correctness and completeness of a system design. The object constraint language (OCL) was defined to add constraints to UML, but it is deficient in strict notations of mathematics and logic that permits rigorous analysis and reasoning about the specifications. In this paper, we investigated how CPS applications modeled using UML deployment diagrams could be formally expressed and verified. We used Z language constructs and prototype verification system (PVS) as formal verification tools. Considering some relevant case studies presented in the literature, we investigated the opportunity of using this approach for validation of static properties in CPS UML models.

Energy saving strategy for video-based Wireless Sensor Networks under field coverage preservation

The demand for video-based wireless sensor networks (WSN) applications has significantly increased. Different from conventional sensor networks, video WSN imply a directional sensing model, complex in-node processing, and large data transfer, thus high clock frequencies and significant radio transmission time. Reducing energy consumption is a key requirement for reliable applications. We propose in this paper a novel energy saving method based on redundant node deactivation while preserving field coverage.

Using Registration Algorithms for Wireless Sensor Network Node Localization

This paper investigates the possibility of using image registration techniques to solve node localization problem in a wireless sensor network based on video sensors. Moreover, the proposed solution adds video-field overlap estimation to classical spatial localization. Several registration algorithms are analyzed and tested for performance evaluation.

Reliable Field of View Coverage in Video-Camera based Wireless Networks for Traffic Management Applications

This paper proposes a new method for real-time distributed image acquisition through wireless networks of traffic monitoring cameras. The goal is to provide comprehensive image acquisition in the presence of dynamic disturbances, which obstruct the field of view (FOV) of the cameras. The paper presents a collaborative online algorithm, which (upon FOV loss) identifies an optimized set of cameras that must be turned on to cover the FOV loss. The set is found using a novel cost function, also discussed in the paper. Experimental results are offered to illustrate the effectiveness of the method in recovering the lost FOV.

Towards UML modeling of cyber-physical systems: A case study for gas distribution

Cyber-physical systems (CPSs) integrate computational devices, actuators, and sensors connected to physical environment in massively distributed heterogeneous systems. CPS applications can be found in various domains. In particular gas distribution systems, designed using CPSs, encounter several problems that need to be solved in order to have a safe and efficient network. This paper proposes an approach based on MDA, UML and goal oriented programming for designing and implementing a CPS model for monitoring gas distribution.

A simulation framework for PSoC based Cyber Physical Systems

This paper presents a framework for testing and validating applications designed for PSoC based CPSs. Programmable System on Chip (PSoC) technology provides a strong support for designing adaptation policies for reconfigurable sensor nodes. Synchronization of such devices in a Cyber Physical System (CPS) requires accurate message flow between them. Each PSoC chip has its own clock unit but it may operate at different clock frequency. Due the system complexity, simulation represents a proper way for efficient debugging and validation. The framework proposed here is based on OMNeT++, which is an event-driven simulator written in C++ that provides excellent extension capabilities.

Stochastic Model-Based Heuristics for Fast Field of View Loss Recovery in Urban Traffic Management Through Networks of Video Cameras

This paper proposes two new heuristic methods for real-time distributed traffic monitoring through video cameras. The goal is to minimize the field-of-view (FOV) loss of the cameras due to dynamic obstacles while considering the timing constraints of the application. The methods utilize different cost functions to select the cameras used in FOV loss recovery. The cost functions are based on a new stochastic model for traffic monitoring, including the dynamics of mobile obstacles, unreliable communication, and resolution and timing constraints. The first cost function addresses deterministic situations by capturing the tradeoff between the quality of recovery and the imposed timing constraints. The second cost function captures stochastic aspects, such as a camera being obstructed by obstacles or experiencing data losses due to unreliable communication. Experiments show that the two methods offer reliable FOV loss recovery for a large variety of conditions. The methods are fast and scale well with the number of monitored cars and cameras. The average FOV loss recovery of the deterministic heuristic is 52%, but the resulting coverage remains close to 100% most of the time, whereas without the recovery scheme, the coverage drops to about 60% about half the time. For time-constrained unreliable communication, the stochastic heuristic offers coverage that is only about 15% less than if communication is unrestricted.

Hierarchical approach for intelligent lighting control in future urban environments

This paper proposes a novel concept and the related architecture for scalable and flexible lighting control in cities. The goal is to minimize the overall energy consumption without affecting safety. We are proposing a two-level control strategy based on qualitative processing. The lower level Zone Lighting Coordination Unit adjusts the lighting intensity of each lamp post through fuzzy logic. The parameters of the fuzzy controller are set by the upper level Lighting Coordination Unit, which uses a knowledge based mechanism. A case study illustrates the two-level control concept.

Towards a model and specification for visual programming of massively distributed embedded systems

Massively distributed embedded systems are rapidly emerging as a key concept for many modern applications. However, providing efficient and scalable decision making capabilities to such systems is currently a significant challenge. This paper proposes a model and a specification language to allow automated synthesis of distributed controllers, which implement and interact through formalisms of different semantics. The paper refers to a case study to illustrate the main capabilities of the proposed concept.

Off-line recognition of handwritten numeral strings composed from two-digits partially overlapped using Convolutional Neural Networks

The objective of the present work is to provide an efficient and reliable technique for off-line recognition of handwritten numerals composed from two digits partially overlapped. It can be used in various applications, like postal code recognition or information extraction from fields of different forms. Proposed solution uses convolutional neural networks (CNNs) and rely on very light preprocessing avoiding segmentation. Test results on a comprehensive well-known character database -NIST SD 19- show a high degree of recognition accuracy.