dataesr/scientific-paragraphs-categorization huggingface dataset:
In this paper, we propose and demonstrate experimentally a new wireless digital encryption hyperchaotic communication system based on radio frequency (RF) communication protocols for secure real-time data or image transmission. A reconfigurable hardware architecture is developed to ensure the interconnection between two field programmable gate array development platforms through XBee RF modules. To ensure the synchronization and encryption of data between the transmitter and the receiver, a feedback masking hyperchaotic synchronization technique based on a dynamic feedback modulation has been implemented to digitally synchronize the encrypter hyperchaotic systems. The obtained experimental results show the relevance of the idea of combining XBee (Zigbee or Wireless Fidelity) protocol, known for its high noise immunity, to secure hyperchaotic communications.
com/content/2013/1/43 signal processing devices, such as field programmable gate array (FPGA), have been widely used to generate numerically the chaotic dynamics or the encryption keys  [27] [28] [29] [30] [31]. The advantage of these techniques is that the parameter mismatch problem does not exist contrary to the analog techniques. In addition, they offer a large possible integration of chaotic systems in the most recent digital communication technologies such as the ZigBee communication protocol. In this paper, a wireless hyperchaotic communication system based on dynamic feedback modulation and RF XBee protocols is investigated and realized experimentally. The transmitter and the receiver are implemented separately on two Xilinx Virtex-II Pro circuits  [32]  and connected with the XBee RF module based on the Wi-Fi or ZigBee protocols  [26, 33].
To ensure and maintain this connection, we have developed a VHSIC (very high speed integrated circuit) hardware description language (VHDL)-based hardware architecture to adapt the implemented hyperchaotic generators, at the transmitter and receiver, to the XBee communication protocol. Note that the XBee modules interface to a host device through a logic-level asynchronous serial port. Through its serial port, the module can communicate with any logic and voltage-compatible Universal Asynchronous Receiver/Transmitter (UART)  [33]. The used hyperchaotic generator is the well-known and the most investigated hyperchaotic Lorenz system  [34]. This hyperchaotic key generator is implemented on FPGA technology using an extension of the technique developed in  [27] [28] [29]  for three-dimensional (3D) chaotic systems.
The 'FPGA implementation of hyperchaotic Lorenz generator' section briefly introduces continuous Lorenz hyperchaotic system, which is used as key stream generators of the proposed digital encryption hyperchaotic modulation. This section then details the hardware architecture used for implementing the Lorenz hyperchaotic generator. A register transfer level (RTL) architecture for embedded hardware implementation of the considered key stream generator is also given in this section. The 'Experimental framework' section presents our experimental framework used to realize and validate the wireless hyperchaotic communication scheme. This section gives details of the transmitter and the receiver blocks with a short description of the XBee RF modules. The 'Wireless real-time data or image transmission tests and results' section presents different real-time results proving that the proposed system is suitable for efficient secure realtime data or image transmissions of wireless sensor networks.
The flowchart describes the fourth order Runge-Kutta (RK-4) numerical method used for resolving the continuous chaotic system models, where x 0 , y 0 , z 0 , and w 0 are the initial conditions, h is the iteration step, and k i , m i , l i , and p i (i = 0 to 3) are the intermediate slopes. In this work, we are interested in the hyperchaotic Lorenz system modeled as follows  [34] : ẋ = a(y -x), ẏ = x(b -z) -y + w, ż = xy -cz, ẇ = -fx. (5) In  [34] , it has been proven that this 4D lorenz system exhibits hyperchaotic behaviors and presents a twodimensional bifurcation diagram for the following parameter conditions : a = 10, c = 8/3, 0 < b < 30, and 0 < f < 15. Therefore, the system preserves its The Matlab simulation result, using the presented RK-4 method, of the (xy) hyperchaotic Lorenz attractor is given in Figure  3.
Hardware architecture To implement the hyperchaotic Lorenz generator, we use an optimal VHDL hardware structural description of the RK-4 method described by the flowchart in Figure  2. Indeed, contrary to the use of automatic code-based design approach which leads to non-optimal VHDL codes (for instance, the Simulink/Matlab automatic code generation tool associated to Xilinx System Generator design tool), the low-level aspect of our digital chaos implementation keeps the user very close from realities of the physical implementation (low-level architecture). Therefore, the results in terms of performance and density of resources used remain within the designer's reach. As to logic exploration architecture, one proposed RTL architecture of the 4D Lorenz hyperchaotic system (Lorenz_Generator block) is depicted in Figure  4.
Experimental framework To test and validate the proposed approach, we have realized the experimental framework depicted in Figure  6. For this purpose, we consider the available XUP Xilinx Virtex-II Pro development embedded platforms for physical hardware implementations  [32]. The XUP System consists of a high-performance Virtex-II Pro FPGA (XCV2PFF896-7) surrounded by peripheral components that can be used to create a complex hardware system. Note that an audio CODEC (AC97) and stereo power amplifier are included on the XUP platform so as to provide complete analog functionality, allowing the external generation of chaotic signals in analog form for real measurements  [40]. Both the transmitter and the receiver are mounted on a Virtex-II Pro Development System  [32]  connected to an XBee module based on Zigbee or Wi-Fi communication protocols  [26, 33].
XBee RF modules XBee modules offer the advantage to interface to a host device through a well-known logic-level asynchronous serial port. In fact, devices having a UART interface can connect directly to the pins of the RF modules  [26, 33]. In our experiment, we use the XBee modules in their transparent mode with the minimum connections VCC, GND, T x , and R x as showed in Figure  7. When operating in this mode, the modules act as a serial line replacement, i. e. , all UART data, consisting of a start bit (low), eight data bits (least significant bit first), and a stop bit (high), received through the R x pin queued up for RF transmission. When RF data is received, the data is sent out the T x pin.
Receiver architecture The receiver architecture is presented in Figure  10. It is composed of four modules : Clock_Generator, Lorenz_Generator, PISO, and serial input/parallel output (SIPO). The first three modules are similar to those of the transmitter but with an adjustment to the receiver. The details of the functioning of each module are as follows: -SIPO. This module is a binary serial-to-parallel converter. Once the start bit is detected at the receiver by the SIPO module, the serial/parallel conversion of the received data begins. At the same time, the module generates a clock signal (clk_lz) at the same frequency as the clk_out clock signal generated by the Clock_Generator module. This means that the generation of the clk_lz clock signal is triggered at each start bit detection. This constitutes our interesting solution to overcome the problem of shifting data frames at the XBee RF module output (T x ).
Indeed, this solution permits to adapt and to synchronize the execution of the implemented receiver architecture to the cadence of the XBee RF module data output (T x ). However, to synchronize the SIPO and the Lorenz_Generator modules, we use a 1-bit command signal (cm). Initially, this last one is set to '0', and it is set to '1' during one clock period only when the converted 32-bit parallel data S r are available at the output of the SIPO module, i. e. , the serial-to-parallel conversion is finished. -Lorenz_Generator. This module is similar to the hyperchaotic Lorenz generator used at the transmitter. This means that it generates the hyperchaotic keys with the same values of the parameters and initial conditions at the transmitter in order to allow the hyperchaotic synchronization as proposed in the 'Hyperchaotic synchronization and encryption technique' section.
Using self-synchronization technique at the receiver side  [32] , the key can be recovered at the receiver and the decryption operation from the transmitted scrambled image with the regenerated key, allowing us to recover the plain image. In the experimental transmission tests, we use binary data encoded on 32-bit fixed-point format with hexadecimal representation as information signal. At the transmitter, these information data are masked by the hyperchaotic samples x of the Lorenz_generator encoded also on 32bit fixed-point data format. The encrypted signal samples S i (t) are then converted to serial data format by the PISO module, sent to its associate XBee Pro RF module according to the considered protocol (Zigbee or Wi-Fi), and then transmitted to the receiver. At the receiver, the associated XBee Pro RF module transmits the received data to the SIPO module according to the asynchronous serial communication protocol to regenerate the received encrypted signal sample format S r (t), allowing for the hyperchaotic synchronization and recovery of the masked information d(t) according the proposed scheme depicted in Figure  1.
The XBee modules offer the advantage to realize a wireless communication application without errors (PER = 0%) according to environment application, distance, disposition, and channel chosen as is shown in  [42]. The maximum bit rate of the proposed system is limited either by the RF modules or implemented hardware logic blocks. Indeed, the hardware FPGA implementations allow parallel/serial and serial/parallel converters with minimum and maximum rates of 25. 36 and 36. 27 Mbps obtained with Virtex II and Virtex V technologies, respectively (see Table  1 ). However, for the considered Zigbee protocol, the maximum bit rate of the proposed system is limited by the RF modules. The hardware FPGA implementation performance (for working clock frequency, see Table  1 ) of the proposed system (at the transmitter and receiver) is considered, and it is larger than the serial interface data rate and better than the bit rate, which is allowed by the considered Zigbee RF modules.
Consequently, the limitation is imposed by the transmission rate of the parallel/serial and serial/parallel converters toward Zigbee http://jivp. eurasipjournals. com/content/2013/1/43 Xbee RF modules while FPGA implementations allow to provide transmission rates to at 25 Mbps. Thereby, for a null distance frame value (N = 0), the obtained data bit rate of the serial communication is 250 kbps (corresponding to a modulation rate of 625 symbols per second or baud, due to the maximum serial interface data rate of the Zigbee protocol based XBee Pro modules [33], and with an operating frequency modulation of 2. 4 GHz. In the case of the Wi-Fi protocol, the maximum bit rate of the proposed system is limited by the work frequency of the implemented hardware modules. Although the FPGA implementation of the Lorenz generator allows to provide a throughput of 80 Mbps (maximal frequency of 25 MHz is allowed by the considered Virtex II platform with an encoded 32-bit encrypted data), the maximum transmission bit rate of the proposed system is limited by the hyperchaotic key generators up to 25 Mbps (for N = 0) and by a corresponding modulation rate of 625,000 baud.
Each pixel value is extended to 40 bits according to the wordlength data frame format of the encryption process and serial transmission  [26, 33]. Consequently, we deduce a time constraint of 40 ms by image to assure that the real-time wireless transmission rate corresponds to a minimum bit rate of 16,384 kbps or modulation rate of 409,600 baud. Therefore, the proposed system based on Wi-Fi XBee modules, which can be performed up to the maximum modulation rate of 625,000 baud, achieves a wireless realtime encrypted transmission suitable for the WSN context. Figure  14.
01 or below 0. 99  [43]. The results of Table  4  show the measured values of P value T, knowing that if P value T ≥ 0. 0001, then the sequences can be considered to be uniformly distributed. Similarly, the minimum pass rate for each statistical test with the exception of the random excursion (variant) test is approximately 0. 972766 for a sample size equal to 300 binary sequences (for more details, see the reference  [43] ). Figure  15  gives the Matlab simulation result of the (xyz) phase space and confirms these statistical results. Indeed, this phase space is occupied by random trajectories proving that the sequences are really uniformly distributed. Consequently, we can conclude that the proposed chaos-based key stream generator successfully passes all the NIST tests and provides good randomness keys.
Conclusions This paper proposes an experimental demonstration of a wireless hyperchaotic communication based on wireless communication protocols suitable for secure real-time data or image transmissions in wireless sensor networks. We have proposed a new digital synchronized modulation based on FHS through a DFM technique between two hyperchaotic generators. The choice of a DFM principle for implementing the FHS between two identical hyperchaotic systems of Lorenz in FPGA shows more robustness than the classic chaotic masking while allowing high transmission rates. In practice, we have associated and adapted the hyperchaotic communication principle with the XBee RF modules by developing a reconfigurable VHDL-based hardware architecture implemented on FPGA technology. Indeed, the proposed system can be used as hard key generator in a hyperchaotic synchronized data or image stream cipher/decipher, and it can be used for synchronizing any four-dimensional continuous chaotic system (such as hyperchaotic Lorenz system) where the master chaotic system is embedded in the proposed FPGA transmitter side and the slave chaotic system is embedded in the FPGA receiver side.
Many real-time transmission tests are carried out between two distanced Virtex II-Pro Xilinx FPGA platforms. The obtained real-time results show the efficiency of the proposed idea consisting on associating the hyperchaotic communication, and the ZigBee or Wi-Fi communication protocols characterized by high immunity against channel noise. Indeed, we could recover correctly the information data on the distance about 20 m using the XBee RF modules at -2 dBm with a PER of 0%. Note that these performances can be improved using the most recent XBee modules. Experimental results applied to image encryption have demonstrated that our approach exhibits attractive performances and is useful in the field of real-time secure wireless data communications. The proposed technique may make it more applicable in such field (video, image, internet, etc.
Open Software System Our system includes a modular software architecture which not only allows for further developments on the applications tested on it, but also a seamless adaptability to numerous fields of application besides heritage valorisation. Furthermore, considering the large number of existing and potential industrial software modellers, we chose to design the core of our software architecture for the highest portability and with a view to a straightforward interfacing to all kinds of 3D modellers: we have so far conducted successful tests with Virtools 4  , 3DVia Studio 5  , OpenSceneGraph 6.
Software Architecture We also wanted the telescope to be as modular as possible. So we introduced an abstraction layer: VRPN 7  (Virtual Reality Peripheral Network) server. VRPN is a free library which allows for a transparent interface between an application (on a computer) and a hardware device (linked to another computer on the network). This library relies on a client-server architecture: the server unit consists of a computer which collects data from the coders and the camera, and the client unit consists of computer whose task is to compute the application. This type of library has numerous advantages: Asynchronous Non-blocking communications. The augmented reality engine is based upon an open-source library such as OpenScenegraph for 3D rendering, ARToolkit 8  for virtual objet insertion; it is connected to a 3D database (produced by the partners of the project TerraNumerica) which contains 3D models of Paris buildings.
CONCLUSION In this paper, we have proposed a complete study on the production of a generic augmented reality Telescope, including the underlying software, hardware, ergonomic constraints, and extensible architecture. The platform we presented is based on dynamic calibration; it can be set up on every site around the world. The software architecture is open and portable and can be interfaced to any kind of software modeller (3DVIA, OpenSceneGraph, etc). We also presented a final use case based on TerraNumerica cartography of Paris, and a testing protocol, together with a practical use case in the "Champs-Elysée" area. The purpose of this use case was heritage valorisation. The System we detailed in this paper is extensible and modular. Once implemented, it can be considered as a research platform, allowing new approaches of observing and thinking the city.
ACKNOWLEDGMENT Some of the works reported in this paper were conducted and sponsored as a part of the CapDigital Business Cluster TerraNumerica 9 project and Futur en Seine 10 digital world festival. We would also like to thank: • Thales Training and Simulation 11 for the valuable information and works on the multi-focal camera calibration module. • Centre des Monuments Nationaux 12 for the production of the information databases and their valuable collaboration for conducting the experimentation from the terrace of the "Arc de Triomphe". • Hyptique 13 agency for the design of graphical information cartel.
4 ). Respecting the ISO-Square standard  [8] , we propose the measurement meta-model as composed in the following structure (Fig. 4 ): (1) Measure: Represents the output value of the measurement; (2) Probe: Represents an entity that captures the data when an event is triggered (e. g. a packet is dropped), an action is performed, or during all of the simulation time. The probe concept is inspired from OPNET 1  structure  [10]. The probe element is associated with structural and behavioral entities from ArchiMate profile. This provides the ability of collecting measurements from elements of the different layers of EA. Probes have different types due to the nature of the data type that they can obtain (e. g. numerical, time). In the verification activity, one may use all the probes that are related to one measurement in one layer of EA, or distribute them between different layers.
This scenario is represented in the business layer of ArchiMate, and shows the correspondence of business actors with the different activities that compose it. 6. 1 Associating probes with the elements of the Business Layer Associating probes with the business layer elements gives the ability of obtaining data from the business domain such as user-related information. Figure  (7)  shows that when the user enters to the conference system joining the group, a function in the application layer called join conference is triggered (called) by the (Enter Conference) activity. This application function triggers a registration procedure in the technology layer, to register the user into the conference service in the simulation technical space. Figure  (9)  presents the Java code that is generated by the MT rules for the business layer elements.
Related work We consider the following aspects during the review: (1) The ability of collecting measurements from structural elements as well as the behavioral ones; (2) Linking automatically the design modeling and Simulation or other execution software technical spaces; (3) Domain Specificity of the approach; (4) The ability to obtain data after executing the design and on high level of abstraction including the scenarios. -In  [15] , the paper describes a model-based approach to create telecom services. They implement the service relying on IP Multimedia Subsystem (IMS) infrastructure and using code generation techniques from the MDE discipline. Using Eclipse software, they could close the abstraction gap between the design and the execution environment, by hiding the low level protocol and architecture details.
Although their approach considers the domain specificity and high abstraction level of the design models, but no measurement capture method appears in their approach; -The  [23]  presents work that is very close to the formalism which we use. The authors apply MDE and rely on DEVS (Discrete EVent Systems Specification) formalism to smooth the modeling and simulation cycle and facilitate the coupling of models using heterogeneous formalisms. They provide the SimStudio software which aims at providing modeling and simulation tool chain. Their approach and ours depend on meta-models that contains different views to the different activities of the tool chain (modeling, simulation). Their approach doesn't have support for structural elements representation while limited to the behavioral ones. Their approach seems to depend on one abstraction level of measuring capability, while we use probes to obtain data from different layers of EA; -The work presented in  [6]  addresses the same scope of service creation activity.
They propose a methodology that takes into consideration the customer and service provider requirements. They apply code generation to produce Java and C++ codes directly from these PIMs, with no mention to simulation tools; -In  [5] , the authors work on context aware services creation process. Not far from our approach, they link between the knowledge modeling and implementation activities, relying on model transformations. Their approach doesn't seem to rely on simulators but on runtime environments such as JVM. Their approach takes the end-user only into consideration, where we take service designer and user models into account thanks to the EA standard. Their approach respects domain specificity and data capturing during and after the execution, but it is only from high abstract models.
Material. Two environments were used in our experiment: virtual and real. The real environment was an area near the Bordeaux hospital, and the virtual environment (VE) was a 3D replica of that environment created in 2006 by engineering students from Bordeaux 2 University, using Virtools software. Significant landmarks (e. g. , signposts, signs, urban furniture, etc. ) as well as an auditory environment (i. e. , urban sounds) were included in the VE. The characteristics of the route were as follows: 1,457 meters, 14 streets, 18 intersections, and 18 direction changes. To manipulate the navigation mode in the VE in the passive condition, participants only visualized the route without any interaction, whereas in the active condition, the participants used a joystick to interact with the VE. In this present experiment, with the future aim of developing a retraining program for patients with orientation disorders, we selected a joystick, because it is an interactor suitable for this population  [39].