Modeling Power Consumption and Temperature in TLM Models

International audienceMany techniques and tools exist to estimate the power consumption and the temperature map of a chip. These tools help the hardware designers develop power efficient chips in the presence of temperature constraints. For this task, the application can be ignored or at least abstracted by some high level scenarios; at this stage, the actual embedded software is generally not available yet. However, after the hardware is defined, the embedded software can still have a significant influence on the power consumption; i.e., two implementations of the same application can consume more or less power. Moreover, the actual software powe

CONTREX: Design of embedded mixed-criticality CONTRol systems under consideration of EXtra-functional properties

The increasing processing power of today’s HW/SW platforms leads to the integration of more and more functions in a single device. Additional design challenges arise when these functions share computing resources and belong to different criticality levels. The paper presents the CONTREX European project and its preliminary results. CONTREX complements current activities in the area of predictable computing platforms and segregation mechanisms with techniques to consider the extra-functional properties, i.e., timing constraints, power, and temperature. CONTREX enables energy efficient and cost aware design through analysis and optimization of these properties with regard to application demands at different criticality levels

CONTREX: Design of embedded mixed-criticality CONTRol systems under consideration of EXtra-functional properties

The increasing processing power of today’s HW/SW platforms leads to the integration of more and more functions in a single device. Additional design challenges arise when these functions share computing resources and belong to different criticality levels. CONTREX complements current activities in the area of predictable computing platforms and segregation mechanisms with techniques to consider the extra-functional properties, i.e., timing constraints, power, and temperature. CONTREX enables energy efficient and cost aware design through analysis and optimization of these properties with regard to application demands at different criticality levels. This article presents an overview of the CONTREX European project, its main innovative technology (extension of a model based design approach, functional and extra-functional analysis with executable models and run-time management) and the final results of three industrial use-cases from different domain (avionics, automotive and telecommunication).The work leading to these results has received funding from the European Community’s Seventh Framework Programme FP7/2007-2011 under grant agreement no. 611146

Techniques for Wireless Channel Modeling in Harsh Environments

With the rapid growth in the networked environments for different industrial, scientific and defense applications, there is a vital need to assure the user or application a certain level of Quality of Service (QoS). Environments like the industrial environment are particularly harsh with interference from metal structures (as found in the manufacturing sector), interference generated during wireless propagation, and multipath fading of the radio frequency (RF) signal all invite novel mitigation techniques. The challenge of achieving the benefits like improved energy efficiency using wireless is closely coupled with maintaining network QoS requirements. Assessment and management of QoS needs to occur, allowing the network to adapt to changes in the RF, information, and operational environments. The capacity to adapt is paramount to maintaining the required operational performance (throughput, latency, reliability and security). This thesis address the need for accurate radio channel modeling techniques to improve the performance of the wireless communication systems. Multiple different channel modeling techniques are considered including statistical models, ray tracing techniques, finite time-difference technique, transmission line matrix method (TLM), and stochastic differential equation-based (SDE) dynamic channel models. Measurement of ambient RF is performed at several harsh industrial environments to demonstrate the existence of uncertainty in channel behavior. Comparison of various techniques is performed with metrics including accuracy, applicability, and computational efficiency. SDE- and TLM-based methods are validated using indoor and outdoor measurements. Fast, accurate techniques for modeling multipath fading in harsh environments is explored. Application of dynamic channel models is explored for improving QoS of wireless communication system. The TLM-based models provide accurate site-specific path loss calculations taking into consideration materials and propagation characteristics of propagating environment. The validation studies confirm the technique is comparable with existing channel models. The TLM-based channel models is extended to compute the site-specific multipath characteristics of the radio channel eliminating the need for experimental measurement. The TLM-based simulator is also integrated with packet-level network simulator to perform end to end-to-end site specific calculation of wireless network performance. The SDE-channel models provide accurate online estimations of the channel performance along with accurate one-step prediction of the signal strength. The validation studies confirm the accuracy of the technique. Application of the SDE-based models for adaptive antenna control is formulated using online recursive estimation

A Magnetic Laser Scanner for Endoscopic Microsurgery

Laser scanners increase the quality of the laser microsurgery enabling fast tissue ablation with less thermal damage. Such technology is part of state-of-the-art freebeam surgical laser systems. However, laser scanning has not been incorporated to fiber-based lasers yet. This is a combination that has potential to greatly improve the quality of laser microsurgeries on difficult-to-reach surgical sites. Current fiberbased tissue ablations are performed in contact with the tissue, resulting in excessive thermal damage to healthy tissue in the vicinity of the ablated tissue. This is far from ideal for delicate microsurgeries, which require high-quality tissue incisions without any thermal damage or char formation. However, the possibility to perform scanning laser microsurgery in confined workspaces is restricted by the large size of currently available actuators, which are typically located outside the patient and require direct line-of-sight to the microsurgical area. Thus, it is desired to have the laser scanning feature in an endoscopic system to provide high incision quality in hard-to-reach surgical sites. This thesis aims to introduce a new endoscopic laser scanner to perform 2D position control and high-speed scanning of a fiber-based laser for operation in narrow workspaces. It also presents a technology concept aimed at assisting in incision depth control during soft-tissue microsurgery. The main objective of the work presented in this thesis is to bring the benefits of free-beam lasers to laser-based endoscopic surgery by designing an end-effector module to be placed at the distal tip of a flexible robot arm. To this end, the design and control of a magnetic laser scanner for endoscopic microsurgeries is presented. The system involves an optical fiber, electromagnetic coils, a permanent magnet and optical lenses in a compact system for laser beam deflection. The actuation mechanism is based on the interaction between the electromagnetic field and the permanent magnets. A cantilevered optical fiber is bended with the magnetic field induced by the electromagnetic coils by creating magnetic torque on the permanent magnet. The magnetic laser scanner provides 2D position control and high-speed scanning of the laser beam. The device includes laser focusing optics to allow non-contact incisions. A proof-of-concept device was manufactured and evaluated. It includes four electromagnetic coils and two plano-convex lenses, and has an external diameter of 13 mm. A 4 74 mm2 scanning range was achieved at a 30 mm distance from the scanner tip. Computer-controlled trajectory executions demonstrated repeatable results with 75 m precision for challenging trajectories. Frequency analysis demonstrated stable response up to 33 Hz for 3 dB limit. The system is able to ablate tissue substitutes with a 1940 nm wavelength surgical diode laser. Tablet-based control interface has been developed for intuitive teleoperation. The performance of the proof-of-concept device is analysed through control accuracy and usability studies. Teleoperation user trials consisting in trajectory-following tasks involved 12 subjects. Results demonstrated users could achieve an accuracy of 39 m with the magnetic laser scanner system. For minimally invasive surgeries, it is essential to perform accurate laser position control. Therefore, a model based feed-forward position control of magnetic laser scanner was developed for automated trajectory executions. First, the dynamical model of the system was identified using the electromagnets current (input) and the laser position (output). Then, the identified model was used to perform feedforward control. Validation experiments were performed with different trajectory types, frequencies and amplitudes. Results showed that desired trajectories can be executed in high-speed scanning mode with less than 90 m (1.4 mrad bending angle) accuracy for frequencies up to 15 Hz. State-of-the-art systems do not provide incision depth control, thus the quality of such control relies entirely on the experience and visual perception of the surgeons. In order to provide intuitive incision depth control in endoscopic microsurgeries, the concept of a technology was presented for the automated laser incisions given a desired depth based on a commercial laser scanner. The technology aims at automatically controlling laser incisions based on high-level commands from the surgeon, i.e. desired incision shape, length and depth. A feed-forward controller provides (i) commands to the robotic laser system and (ii) regulates the parameters of the laser source to achieve the desired results. The controller for the incision depth is extracted from experimental data. The required energy density and the number of passes are calculated to reach the targeted depth. Experimental results demonstrate that targeted depths can be achieved with \ub1100 m accuracy, which proves the feasibility of this approach. The proposed technology has the potential to facilitate the surgeon\u2019s control over laser incisions. The magnetic laser scanner enables high-speed laser positioning in narrow and difficult-to-reach workspaces, promising to bring the benefits of scanning laser microsurgery to flexible endoscopic procedures. In addition, the same technology can be potentially used for optical fiber based imaging, enabling for example the creation of new family of scanning endoscopic OCT or hyperspectral probes

Understanding multidimensional verification: Where functional meets non-functional

Abstract Advancements in electronic systems' design have a notable impact on design verification technologies. The recent paradigms of Internet-of-Things (IoT) and Cyber-Physical Systems (CPS) assume devices immersed in physical environments, significantly constrained in resources and expected to provide levels of security, privacy, reliability, performance and low-power features. In recent years, numerous extra-functional aspects of electronic systems were brought to the front and imply verification of hardware design models in multidimensional space along with the functional concerns of the target system. However, different from the software domain such a holistic approach remains underdeveloped. The contributions of this paper are a taxonomy for multidimensional hardware verification aspects, a state-of-the-art survey of related research works and trends enabling the multidimensional verification concept. Further, an initial approach to perform multidimensional verification based on machine learning techniques is evaluated. The importance and challenge of performing multidimensional verification is illustrated by an example case study

Experimental and Computational Investigations of Heat Transfer Systems in Fluoride Salt-cooled High-temperature Reactors

Fluoride salt-cooled high-temperature reactors (FHRs) face a number of challenges similar to those faced by other Generation IV advanced reactor concepts. Predicting heat transfer in these systems accurately and reliably is one major challenge. Another is ensuring the safety of these systems during challenging operating conditions across the design basis envelope. Finally, achieving good economics to compete in a modern power generation portfolio is necessary for moving any nuclear power plant concept past the pre-conceptual stage. This dissertation attempts to support, from a thermal-hydraulics research standpoint, the case that the FHR can attain these goals. The dissertation focuses on several aspects of the design. The common thread through the different studies is ultimately rooted in improving plant safety and economics. This dissertation has four major contributions in support of the FHR: experimental investigation of a directional direct reactor auxiliary cooling system (DRACS) heat exchanger (DHX), experimental investigation of twisted versus plain tube heat transfer for molten salt heat exchangers, and two computational studies, one on DRACS reliability and one on heat exchanger optimization. The results for the four studies are presented and discussed. The directional DHX study was performed using a hydrodynamic experimental setup with water as a working fluid and heat transfer performance inferred. The experimental heat transfer work was performed using a simulant fluid, Dowtherm A, to match the important non-dimensional heat transfer parameters. The computational DRACS reliability study was performed using MATLAB and RELAP5-3D, and the computational heat exchanger optimization study was performed using Python and available metaheuristic algorithms. The implications of the various studies are tied together in the conclusions section, with suggestions for future work

VPLanet: The Virtual Planet Simulator

We describe a software package called VPLanet that simulates fundamental aspects of planetary system evolution over Gyr timescales, with a focus on investigating habitable worlds. In this initial release, eleven physics modules are included that model internal, atmospheric, rotational, orbital, stellar, and galactic processes. Many of these modules can be coupled simultaneously to simulate the evolution of terrestrial planets, gaseous planets, and stars. The code is validated by reproducing a selection of observations and past results. VPLanet is written in C and designed so that the user can choose the physics modules to apply to an individual object at runtime without recompiling, i.e., a single executable can simulate the diverse phenomena that are relevant to a wide range of planetary and stellar systems. This feature is enabled by matrices and vectors of function pointers that are dynamically allocated and populated based on user input. The speed and modularity of VPLanet enables large parameter sweeps and the versatility to add/remove physical phenomena to assess their importance. VPLanet is publicly available from a repository that contains extensive documentation, numerous examples, Python scripts for plotting and data management, and infrastructure for community input and future development.Comment: 75 pages, 34 figures, 10 tables, accepted to the Proceedings of the Astronomical Society of the Pacific. Source code, documentation, and examples available at https://github.com/VirtualPlanetaryLaboratory/vplane

Technology for the Future: In-Space Technology Experiments Program, part 2

The purpose of the Office of Aeronautics and Space Technology (OAST) In-Space Technology Experiments Program In-STEP 1988 Workshop was to identify and prioritize technologies that are critical for future national space programs and require validation in the space environment, and review current NASA (In-Reach) and industry/ university (Out-Reach) experiments. A prioritized list of the critical technology needs was developed for the following eight disciplines: structures; environmental effects; power systems and thermal management; fluid management and propulsion systems; automation and robotics; sensors and information systems; in-space systems; and humans in space. This is part two of two parts and contains the critical technology presentations for the eight theme elements and a summary listing of critical space technology needs for each theme