Using standards to integrate soft real-time components into dynamic distributed architectures

A pervasive application domain today is one in which independently developed real-time components participate in a dynamic and decentralized way from distributed environments. Several challenges arise from this domain, related with participant heterogeneity, transient behavior, scalability or quality of service. The use of standards is important here, where a multidiscipline approach is required. We propose ServiceDDS, a framework that combines different standard technologies to solve the problems related with the integration of components into the described environment. ServiceDDS is based on DDS to support dynamic distributed interactions, XMPP to provide Web access, and RTSJ for real-time performance.     

Cyberphysical systems security applied to telesurgical robotics

Researchers in telesurgical robotics and security collaborated to develop the Secure ITP, a security enhancement to the Interoperable Telesurgery Protocol (ITP). The ITP defines the structure for communication between telesurgery robots and controllers and has been adopted and tested by fourteen research groups in telesurgical robotics. The Secure ITP uses open source software tools and follows guidelines in Federal Information Processing Standards (FIPS) documents published by the National Institute of Standards and Technology (NIST) to create asecurity enhancement prototype for demonstration purposes and tofacilitate the development of new security technologies which addressthe stringent requirements of telesurgery.     

Automatic parallelisation for LTI MIMO state space systems using FPGAs. An optimisation for cost & performance

The parallelism attained by the use of Field Programmable Gate Arrays (FPGAs) has shown remarkable potential for accelerating control systems applications. This comes at a time when well established methods based on inherited serial Central Processor Units (CPUs) cannot guarantee solutions for the increasing execution speed demands. However, the transition from serial to parallel architectures represents a tremendous challenge due to overwhelming numbers of unexplored options and conflicting factors. The work presented achieves a parallelisation characterisation for generic MIMO systems using stand-alone FPGA implementations. The main contribution is that a very fine subset of possible serial/parallel implementations is obtained. This is used to achieve a flexible trade-off between cost and performance. Automatic optimisation of latency, occupied FPGA area and execution speed is attained and justified in respect to most of the feasible scenarios.     

A flexible layered control policy for resource allocation in a sensor grid

The paper proposes a flexible layered control policy for sensor resource allocation in a sensor grid. In order to allocate sensor resources in the system to maximize the sensor grid utility, different controllers are deployed at three levels: a job-level controller, an application group controller, and a sensor grid system controller. At the lowest levels, job-level controllers perform fast, frequent, local adaptation for optimizing a single sensor grid application at a time, while, at the highest levels, sensor grid system controllers perform less frequent control actions to optimize all applications. Sensor grid system control considers all sensor grid applications in response to large system changes at coarse time granularity. Sensor grid system control exploits the interlayer coupling of the resource layer and the application layer to achieve a system-wide optimization based on the sensor grid users’ preferences. Job-level control adapts a single application to small changes at fine granularity. The layered control system uses a set of utility functions to evaluate the performance of sensor grid applications and groups. The control system chooses control actions that would result in a higher level of utility. In the simulation, a performance evaluation of the algorithm is carried out.     

Utilization-based pricing for power management and profit optimization in data centers

Traditional load balancing approaches may spread the load on more computers as long as the performance in terms of response time or cost is minimized. Nowadays power is a growing cost factor for data centers. In this paper, from the service provider’s point of view, the load balancing decision is made based on whether power consumption can be reduced or more profit can be earned. To achieve this, we design pricing algorithms to influence the load distribution. Both algorithms take into account the utilization of computers besides other factors, such as prices and power costs. In the first algorithm, we design pricing functions with respect to the computer utilization to encourage or discourage resource usage. In the second algorithm, we focus on the profit that a service provider can earn after deducting power cost from its revenue. We formulate this profit optimization problem and derive the optimum price solution.     

BPMN: An introduction to the standard

The Business Process Model and Notation (BPMN) is the de-facto standard for representing in a very expressive graphical way the processes occurring in virtually every kind of organization one can think of, from cuisine recipes to the Nobel Prize assignment process, incident management, e-mail voting systems, travel booking procedures, to name a few. In this work, we give an overview of BPMN and we present what are the links with other well-known machineries such as BPEL and XPDL. We give an assessment of how the OMG's BPMN standard is perceived and used by practitioners in everyday business process modeling chores.     

Performance evaluation of priority CSMA-CA mechanism on ISA100.11a wireless network

The International Society of Automation recently released ISA100.11a as an open standard for reliable wireless networks for industrial automation. ISA100.11a uses the TDMA scheme in the medium access layer to provide deterministic services. However, ISA100.11a adopts the CSMA-CA mechanism with priorities for retransmission from failure on dedicated links, sporadic data, and network configuration.This paper evaluates ISA100.11a CSMA-CA by simulation, considering the effects of backoff procedures and priority settings to probability of collision and successful use of slots. It's demonstrated that a high number of priority classes enable better network utilization resulting in less number of packets exceeding their lifetime.     

Experimental study on the package of high-g accelerometer

In this paper, the effect of the package die adhesive and package shell on the performances of silicon based MEMS high-g accelerometers was reported. Using Raman spectroscopy, the residual stress caused by different package die adhesive thickness and different package shell material was characterized. It can be concluded from the testing results that: with thicker die adhesive, the residual stress increment was much smaller; the piezoresistance variation caused by this residual stress was much smaller; and the temperature shift of the output voltage was much smaller. Comparing with the ceramic package, the stainless steel package has bigger sensitivity and bigger anti-overload ability.     

A wind-flutter energy converter for powering wireless sensors

This paper describes a low-speed wind energy harvesting system that transfers aerodynamically induced flutter energy into electrical energy. A random airflow generates mechanical vibrations due to the fluid-structure interaction between a flexible belt and the airflow. An electromagnetic resonator with copper coils and a permanent magnet is designed to efficiently harvest electrical energy from the induced mechanical vibrations. Different groups of springs are compared at various wind conditions to maximize the power output. Typically ∼7 mW of electrical energy can be obtained at ∼3 m/s wind speed with a 1 m long belt. A power conditioning circuit with a charge pump and a DC-DC converter is used to convert the generated voltage into a stable 3.3 V DC for consumption. It is demonstrated that this generator can be used to drive a commercial wireless temperature sensor.     

Influence of doping BiYO3 and Nb2O5 on PTCR characteristics of BaTiO3 thermistor ceramics

Nb₂O₅-doped (1 − x)Ba_0.96Ca_0.04TiO₃-xBiYO₃ (where x = 0.01, 0.02, 0.03 and 0.04) lead-free PTC thermistor ceramics were prepared by a conventional solid state reaction method. X-ray diffraction, scanning electron microscope, Agilent E4980A and resistivity-temperature measurement instrument, were used to characteristic the lattice distortion, microstructure, temperature dependence of permittivity and resitivity-temperature dependence. It was revealed that the tetragonality c/a of the perovskite lattice, the microstructure and the Curie temperature changed with the BiYO₃ content. In order to decrease the room temperature resistivity, the effect of Nb₂O₅ on the room temperature resistivity was also studied, and its optimal doping content was finally chosen as 0.2 mol%. The 0.97Ba_0.96Ca_0.04TiO₃-0.03BiYO₃-0.002Nb₂O₅ thermistor ceramic exhibited a low ρ_RT of 3.98 × 10³ Ω cm, a typical PTCR effect of ρ_max/ρ_min > 10³ and a T_c of 153 °C.