Compact personal distributed wearable exposimeter

A compact wearable personal distributed exposimeter (PDE) is proposed, sensing the power density of incident radio frequency (RF) fields on the body of a human. In contrast to current commercial exposimeters, our PDE, being composed of multiple compact personal wearable RF exposimeter sensor modules, minimizes uncertainties caused by the proximity of the body, the specific antenna used, and the exact position of the exposimeter. For unobtrusive deployment inside a jacket, each individual exposimeter sensor module is specifically implemented on the feedplane of a textile patch antenna. The new wearable sensor module's high-resolution logarithmic detector logs RF signal levels. Next, on-board flash memory records minimum, maximum, and average exposure data over a time span of more than two weeks, at a one-second sample period. Sample-level synchronization of each individual exposimeter sensor module enables combining of measurements collected by different nodes. The system is first calibrated in an anechoic chamber, and then compared with a commercially available single-unit exposimeter. Next, the PDE is validated in realistic conditions, by measuring the average RF power density on a human during a walk in an urban environment and comparing the results to spectrum analyzer measurements with a calibrated antenna

Digital twins: Understanding the added value of integrated models for through-life engineering services

Digital twins are digital representations of physical products or systems that consist of multiple models from various domains describing them on multiple scales. By means of communication, digital twins change and evolve together with their physical counterparts throughout their lifecycle. Domain-specific partial models that make up the digital twin, such as the CAD model or the degradation model, are usually well known and provide accurate descriptions of certain parts of the physical asset. However, in complex systems, the value of integrating the partial models increases because it facilitates the study of their complex behaviours which only emerge from the interactions between various parts of the system. The paper proposes that the partial models of the digital twin share a common model space that integrates them through a definition of their interrelations and acts as a bridge between the digital twin and the physical asset. The approach is illustrated in a case of a mechatronic product - a differential drive mobile robot developed as a testbed for digital twin research. It is demonstrated how the integrated models add value to different stages of the lifecycle, allowing for evaluation of performance in the design stage and real-time reflection with the physical asset during its operation

Fault Tolerant Power Supply for Aircraft Store Interface

This paper brings out the design of a fault-tolerant power supply unit for the aircraft-store interface. This switched mode power supply provides multiple 30 V regulated and isolated DC outputs required for pre-launch preparations and auto-launch operations of avionic sub-systems in a store. 3Ø-115V-400Hz-AC supply as well as 27V-DC supply are available from a fighter aircraft for powering up of any store. Power (wattage) output from 27V/10A DC is inadequate to power up various onboard avionic sub-systems in guided stores involving seekers and other avionics. Hence, it is planned to convert available high power 3Ø-115V-400Hz-AC supply for applications requiring higher wattages (of the order of 500 watts or more). This power supply provides multiple output options of 30V regulated and isolated DC supply with multiple input supplies from Aircraft, viz. 3Ø-115V-400Hz-AC, 1Ø-115V-400Hz-AC and 27V DC. One of the outputs provided is with hold-up capacitors, to cater for any input power interruptions as per requirements of MIL-STD-704F and GOST-19705-89 standards. This power supply is a ready-to-connect device and essentially consists of housing, components of DC to DC conversions, EMI/EMC filters, solid state power controllers, control switches, and control circuitry for monitoring signals

The Influence of Test Parameters on TEM Cell Measurements of ICs

The IEC 61967-2 TEM cell standard allows for variations in test parameters which may cause variations in the measured emissions from integrated circuits (ICs). To test the impact of these parameters, two printed circuit boards were designed within the IEC standard using poor PCB design strategies and using good design strategies. Emissions from three pin-for-pin compatible 8051 microcontrollers were tested. Emissions were measured using both PCBs, changing the PCB configuration, and changing test parameters like the program running on the IC, the rise time of the input clock, and I/O switching. Emissions from the poor PCB were about 3-8 dB higher than emissions from the good PCB. A change in the program run by the IC, the clock rise-time, and I/O caused a 4-15 dB change in emissions. Emissions differed considerably among the ICs. Possible causes for variations in emissions with the test parameters are discussed

Development of a self balanced robot and its controller

Two wheeled balancing robots are based on inverted pendulum configuration which relies upon dynamic balancing systems for balancing and maneuvering. This project is based on the development of a self-balanced two wheeled robot which has a configuration similar to a bicycle. These robot bases provide exceptional robustness and capability due to their smaller size and power requirements. Outcome of research in this field had led to the birth of robots such as Segway, Murata boy etc. Such robots find their applications in surveillance & transportation purpose. Here, in particular, the focus is on the electro-mechanical mechanisms & control algorithms required to enable the robot to perceive and act in real time for a dynamically changing world. Using an Ultrasonic sensor and an accelerometer we get the information about the tilt of the robot from its equilibrium position. Balancing was done using a servo motor, a DC motor and a control momnt gyroscope. While these techniques are applicable to many robot applications, the construction of sensors, filters and actuator system is a learning experience

Smart objects embedded production and quality management functions

In this paper, smart objects embedded production and quality management functions are proposed, to promote accurately support decision-making processes, from the shop floor level up to higher decision-making levels. The proposed functions contribute for different kind of problems solving in production and quality management, such as production planning and control, scheduling, factory supervision, real-time data acquisition and processing, and real-time decision making. The web access at different middleware devices and tools, at different decision levels, along with the use of integrated algorithms and tools, embedded in smart objects, promotes conditions for better decision-making for optimized use of knowledge and resources in production systems. The relevance of the proposed smart objects embedded production and quality management functions has been validated positively in a manufacturing company.The authors wish to acknowledge the support of the Fundação para a Ciência e Tecnologia (FCT), Portugal, through the grants: “Projeto Estratégico – UI 252 – 2011–2012” reference PEstOE/EME/UI0252/2011, and “Ph.D. Scholarship Grant” reference SFRH/BD/85672/2012.info:eu-repo/semantics/publishedVersio

PERFORMANCE OF HYBRID SYSTEM FOR AUTOMOBILE

Studies on new fuel-saving technologies have been popular in recent years because of decreasing global crude oil supplies and growing environmental concerns. The price of crude oil, according to the Department of Energy (2007), is over 400% higher than ten years ago (Figure 1.1) and is likely to continue to surge in the future because of shrinking oil supplies. To reduce oil consumption byground vehicles, the Corporate Average Fuel Economy (CAFE) was enacted by the US Congress in 1975. The CAFE legislation is overseen by the National Highway Traffic Safety Administration (NHTSA), which sets fuel economy standards for cars and light trucks (trucks, vans, and sport utility vehicles) sold in the US and other countries fallow it's rule as suitable change . While the CAFE standards have remained relatively constant for the last twenty years, the discussion of increasing it is significant in the past fifteen years regarding shrinking oil supplies and increasing oil demand

Field oriented control of single and cascaded doubly-fed induction machines

PhD ThesisA single doubly-fed induction machine (SDFM) is a wound rotor induction machine with the stator connected to a supply network and the rotor fed by a bi-directional converter. A cascaded doubly-fed induction machine (CDFM) is a. connection of two wound rotor induction machines with the rotors connected electrically and mechanically thus avoiding brushes. One stator is connected to the supply network and the other is fed by a bidirectional converter. Both schemes, the SDFM and the CDFM, have in common that the VA-rating of the power converter is reduced compared to a singly-fed system. This thesis presents investigations of the field oriented control for the SDFM and the CDFM. - After reviewing and categorising doubly-fed machines a thorough steady state analysis and stator flux oriented control treatment of the SDFM is presented. Although the steady state analysis and the field oriented control of a SDFM is well established it is necessary that this is included as foundation for the CDFM control behaviour and for the sensorless control investigations. Steady state analysis of the CDFM highlights similarities to the SDFM. Two different field oriented control schemes are applied to the CDFM. A previously developed combined flux oriented scheme is modified to be applicable to a CDFM consisting of any machine combination. Furthermore, the scheme is simplified by removing a mathematical control extension in the q-axis, which has a stabilising effect on the control performance. Justified by steady state analysis the stator flux oriented control structure initially developed for the SDFM is applied to the CDFM. Two variations of a position sensorless scheme taking advantage of the proportionalitics between stator and rotor quantities are applied to the SDFM. Differentiating the estimated position angle allows the schemes to be extended for speed control purposes. The performance of the scnsorless field oriented control methods are also investigated on the CDFM. Harmonic analysis of the SDFM / CDFM systeme stablishes harmonic sources and harmonic current propagation through the system. A theoretical harmonic current prediction process incorporating simulation and steady state modeling delivers good results. All theoretical investigations are confirmed by experimental results. The experimental realtime controlled drive system consists of two 2.25 kW wound rotor induction machines, a bidirectional IGBT converter and the control hardware comprises two 8OC167 microcontrollers.Department of Electrical and Electronic Engineerin