Mihai Hulea

Wi-sensors: A low power Wi-Fi solution for temperature and humidity measurement

This paper presents a complete solution for temperature and humidity monitoring using low-power wireless devices, called Wi-Sensors. The Wi-Sensors use a RN-131C Wi-Fi chip as the core microcontroller and 4 configurable digital input/output lines to which temperature sensors can be attached. The digital 1-Wire and DHT22 protocols had been implemented in the embedded application running on the device. Therefore, for temperature and humidity measurements, any of the sensors operating with one of these two protocols can be used. The existing Wi-Fi 802.11 infrastructure can be used in order to send measurement data to remote destinations. The proposed solution also incorporates a data viewer and data processing application, which provides functionalities for alarming the users by email or by SMS in case previously configured limits are exceeded.

Controller synthesis method for Discrete Event Systems

Many applications contain plants that are Discrete Events Systems (DES). They have to be controlled such that DES fulfills some specifications like: avoid the deadlocks, reach or avoid the reaching of some given states, execute or avoid the execution of some given sequences of events, execute cyclically sequences of events with the shortest periods, etc. In the current study the plants are modeled by Delay Time Petri Nets (DTPN) and the controllers are Time Petri Nets (TPN) models. The controllers can be described by a particular Time Petri Net Language (TPNL). The TPNL descriptions can be transformed into Lisp descriptions. The latest are used by a Genetic Programming (GP) method for the controller synthesis such that DES meets most accurately the system requirements.

Distributed scheduling for real-time railway traffic control

The increase of railway traffic efficiency and flexibility requires new real-time scheduling and control methods. New charter trains have to be added continuously without disturbing the other (periodic) train moves or decreasing the safety conditions. A distributed method to schedule new trains such that their real-time constraints are fulfilled is presented. The trains have timelines to meet and hence the deadlines are extracted taking into account the included laxity. The trains have pre-established routes specifying the stations and required arrival times. The paths containing the block sections from one station to another are dynamically allocated without leading to deadlocks.

Fingerprint recognition distributed system

The paper proposes a distributed identification and verification system which integrates fingerprint recognition and Global Positioning System methods. The system is composed of a number of mobile fingerprinting terminals which communicate with data processing units using GSM\GPRS technology. The motivation for integrating GPS technology in an identification system is to add a supplementary security level by granting access based on area localization. In order to further increase the system security a cryptographic module is used to encrypt / decrypt messages passed between the distributed components. The system architecture is presented and main modules are described.

Self-healing capabilities through wireless reconfiguration of FPGAs

This paper presents a solution for the Wi-Fi reconfiguration of FPGAs. A design that manages the reconfiguration process of a Xilinx Spartan-3 FPGA by using a Wi-Fi Tag4M device that receives reconfiguration data wirelessly from a Configuration Server was developed. This research is especially important for adding self-healing capabilities to large and complex digital systems.

Dynamic Wi-Fi Reconfigurable FPGA Based Platform for Intelligent Traffic Systems

This chapter proposes a software and hardware platform based on a FPGA board to which a Wi-Fi communication device has been added in order to make remote wireless reconfiguration possible. This feature introduces a high level of flexibility allowing the development of applications which can quickly adapt to changes in environmental conditions and which can react to unexpected events with high speed. The capabilities introduced by wireless technology and reconfigurable systems are important in road traffic control systems, which are characterized by continuous parameter variation and unexpected event and incident occurrence. Intelligent Transportation System (ITS) is the term commonly used to describe the employment of electronic devices for the management of road traffic and other types of transportation networks for improving decision making by operators and users. There are many new available technologies which can be used for increasing the efficiency of road systems and many cities are introducing ITS models as pilot schemes to test their effectiveness. Reconfigurable hardware offers many benefits and this led to its use in the ITS field also. Traffic light systems implemented on FPGAs were developed and examples can be found in the literature (El-Medany & Hussain, 2007; Zhenggang et al., 2009). This research led to the conclusion that FPGA based devices can be a good solution for this type of systems conferring them scalability, adaptability and stability, and increasing their efficiency (Zhenggang et al., 2009). FPGAs had also been used in vehicle-to-vehicle communication (V2V), the authors of (Sander et al., 2009) presenting a V2V communication system based on this technology and special mechanisms that exploit its benefits. The result consists of a modular and flexible framework for software routines which in the same time supports critical tasks with special hardware accelerators. The modularity achieved with the help of FPGA technology allows the system to react to changes in the environmental conditions or in the user demands.

Finding intermodal and multi-objective time-dependent best routes with exact algorithm

The paper presents a solution of finding the Pareto front for the intermodal and multi-objective time-dependent shortest path problem from a source to a destination. In the considered case, the travel time and route cost must be minimized. A mathematical model of the multimodal time-dependent freight transport network is constructed and then an exact multi-objective algorithm is proposed and implemented. Finally, the performance and effectiveness of the method are assessed by analyzing the algorithms behavior when different networks parameters change.

Two stage scheduling method of touristic transport in multimodal networks

The presented paper proposes a method suitable to support scheduling activities in multimodal transport networks, whose adapted structures correspond to specific requirements of actual tourism services. Considering characteristic aspects of the application type, a two-stage approach was chosen to find an appropriate solution. First, a Delay Time Petri Nets (DTPN) model was developed to describe all touristic routes and their associated activities in the considered area. Then, using the elaborated model and following a visit planning, Genetic Algorithms were utilized to find convenient schedules for transport activities. For simulation purposes, scenarios inspired from real situations were chosen. The obtained results lead to the elimination of critical values of time that could generate unwanted behaviors.

Modular hybrid control system with Petri-Nets enhanced components for hydro power plant control

Modularization and hierarchical construction are key factors for step-wise refinement of complex system models. Modularity can favor incremental system development allowing the modeler to focus on separate parts with functional and temporal behaviors linked by interfaces exposed to the rest of the model. The paper proposes a method for developing software architectures applied in hybrid control systems. The method extends the RT-UML (Real-Time Unified Modeling Language) enhancing the capsules with Petri nets models and functions performing fuzzy logic inferences. The method is used for a hydro-power plant control to show its applicability to a kind of symbiotic control defined here.

WiPlatform, a sensing and event processing platform

This paper describes the WiPlatform, a scalable, sensing and event processing solution with applicability in building home automation systems, environmental monitoring systems, home care and other related applications. At the base of the system stays the WiSensors, a low power 802.11 Wi-Fi device powered by an RN-131C chip to which various sensors and actuators can be connected. Depending on the application requirements, a network of WiSensors with different sensing and action capabilities can be created. For each application a coordinator responsible for managing devices in the network and communicating with the application server, is required. The proposed solution presents a high level of flexibility, implementing a dynamic reconfiguration mechanism where the coordinator can be reprogrammed to act according the specific application and user needs.