Using Bond-Graph Technique for Modelling and Simulating Railway Drive Systems

This work presents the application of Bond-Graph Technique to modelling and simulating the behaviour of railway transport as a tool for studying its dynamic behaviour, consumption and energy efficiency, and environmental impact. The basic aim of this study is to make a contribution to the research and innovation into new technologies that will lead to the discovery of ever more efficient environmentally-friendly transport. We begin with an introduction to the study of longitudinal train dynamics as well as a description of the most currently used railway drive systems. Bond-Graph technique enables this modelling to be done systematically taking into account all the fields of science and technology involved while bringing together all the mechanical, electrical, electromagnetic, thermal, dynamic and regulatory aspects. Once the models have been developed, the behaviour of the drive systems is simulated by reproducing actual railway operating conditions along a standard section of track. Through a detailed study of the simulation results and choosing the most significant parameters, a comparison can be made of how the different systems perform. We end with the most important conclusions from which it can be deduced which drive systems are comparatively more efficient and environmentally-friendly

Comparative Study of Railway Drive Systems Using Bond-Graph

Since the first railways were built, they have not ceased to increase their capacity for transport, speed and energy consumption. This paper presents a comparative study of how present-day railway drive systems perform. Special emphasis is placed on consumption and energy efficiency. By using theoretical computer simulation models, simulations are conducted of the performance of present-day railway drive systems under certain specific boundary conditions. Bond-Graph Technique has been used to design the models. This technique is widely known and accepted for its suitability and capability for modeling dynamic systems in any field of science or technology, and particularly for modeling vehicular systems. Modeling is done systematically taking account of all the mechanical, dynamic, electrical, electromagnetic and regulation phenomena involved in the operation of railway drive systems. A detailed study of the simulation results has enabled a comparative analysis to be conducted of the most significant variables. Important conclusions have been drawn from this analysis about the drive systems that have been shown to be comparatively more efficient

Application of quantum magnetometers to security and defence screening

Over recent years the sensitivity of alkali-metal vapour magnetometers has been demonstrated to surpass that of even Superconducting Quantum Interference Devices (SQUIDs), the current commercial gold standard in laboratory weak- field magnetometry sensing. Here we present a proof-of-principle approach to building an RF atomic magnetometer which is robust, portable, tunable, non-invasive and operable at room temperature in an unshielded environment. In view of these characteristics, we discuss the potential application of alkali-metal magnetometry in imaging concealed objects, non-destructive evaluation of the structural integrity of metallic objects (e.g. pipelines and aircraft), and detection of rotating motors. We present a cost-effective approach to operating an atomic magnetometer in a Magnetic Induction Tomography (MIT) modality, to non-invasively map the conductivity of conductive objects concealed by conductive materials remotely and in real time. This is achieved by measuring the secondary eld in the subject due to eddy currents circulating as a result of application of a tunable radio-frequency oscillating eld, which overcomes the bandwidth and sensitivity limitations of using coils for sensing as in conventional MIT. In addition, we demonstrate the use of the atomic magnetometer for the remote detection of DC and AC electric motors with an improved response compared with a commercial fluxgate magnetometer in the sub 50 Hz regime (particularly detection down to 15 Hz). Its capability for non-invasive measurement through concrete walls is established, with potential for use in industrial monitoring and detection of illicit activity. Finally, the possibility of detection of submerged targets or for the atomic magnetometer to be mounted on submarine vehicles was explored. Promising results were obtained, but further investigation is required in this environment to establish this as a viable marine detector

Investigating the mechanisms of action of VGF-derived peptides in the nervous system

The VGF neurosecretory protein, first identified as a nerve growth factor (NGF) inducible gene product, is selectively synthesised predominantly in neuronal and neuroendocrine cells. The ~68 kDa VGF protein sequence is rich in paired basic amino acids, and thus the protein undergoes endoproteolytic cleavage to produce smaller peptides, which are stored in dense core vesicles and released upon stimulation via the regulated secretory pathway both in vitro and in vivo. Several of these VGF-derived peptides have been characterised and are involved in energy homeostasis, reproductive processes, synaptic plasticity as well as pain modulation. A number of studies have observed an increase in VGF gene expression in various pain models and more recently the VGF-derived peptides, TLQP-21, LQEQ-19 and TLQP-62 showed direct modulation of inflammatory and neuropathic pain when applied in vivo. The molecular mechanisms of action of VGF-derived peptides are not well understood and were investigated in this study. The TLQP-21 peptide, but not LQEQ-19, was shown to dose-dependently induce an increase in intracellular Ca2+ levels from cellular internal stores in brain- and spinal cord-derived primary microglia, in >65 % of the cell population in vitro. Three hour treatment of primary microglia with TLQP-21 (100 nM) induced a 2.78 fold increase in Ccl11 and a 2.28 fold decrease in Cxcl9 gene expression levels relative to the vehicle control (Student's t-test; p ≤ 0.05). Biochemical analysis using affinity chromatography and LC-MS/MS techniques identified the gC1q-R protein as a potential binding partner / receptor for TLQP-21. The gC1q-R protein is a ubiquitously expressed, multi-compartmental protein involved in complement activation, inflammatory processes and the plasma bradykinin formation pathway. These results tentatively suggest that TLQP-21 may contribute to the modulation of pain through activation of primary microglia and potentially involve interactions with components of the complement system. The findings highlight the importance of VGF-derived peptides in pain research and could lead to new perspectives and targets for pain therapeutics

Technology 2000, volume 1

The purpose of the conference was to increase awareness of existing NASA developed technologies that are available for immediate use in the development of new products and processes, and to lay the groundwork for the effective utilization of emerging technologies. There were sessions on the following: Computer technology and software engineering; Human factors engineering and life sciences; Information and data management; Material sciences; Manufacturing and fabrication technology; Power, energy, and control systems; Robotics; Sensors and measurement technology; Artificial intelligence; Environmental technology; Optics and communications; and Superconductivity

Alpha particle detection in nuclear reactors using solid-state track recorders

Imperial Users onl

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Large Space Antenna Systems Technology, part 1

A compilation of the unclassified papers presented at the NASA Conference on Large Space Antenna Systems Technology covers the following areas: systems, structures technology, control technology, electromagnetics, and space flight test and evaluation