453 research outputs found
Smart Rocks and Wireless Communication System for Real-Time Monitoring and Mitigation of Bridge Scour -- A Proof-of-Concept Study
This study aims to integrate commercial measurement and communication components into a scour monitoring system with magnets or electronics embedded in smart rocks, and evaluate and improve its performance in laboratory and field conditions for the movement of smart rocks. Properly-designed smart rocks were found to be automatically rolled into the very bottom of a scour hole and can give critical information about the maximum scour depth and effectiveness of rip-rap mitigation strategies. Four types of smart rock technologies were investigated in this proof-of-concept phase of study, including passive with embedded magnets, active with magneto-inductive communication, active with controllable magnet rotation, and active with acoustic communication. Their performances were evaluated against three criteria: 1) movement accuracy within 0.5 m, 2) transmission distance between 5 and 30 m, and 3) at least one measurement every 15 minutes. Test results demonstrated that the proposed smart rocks are cost-effective, viable technologies for bridge scour monitoring
Determining the Position and Orientation of In-body Medical Instruments Using Reactive Magnetic Field Mapping
There has been a huge demand for localizing in-body medical instruments (IBMI), such as wireless capsule endoscope (WCE) and nasogastric tube (NGT). Some stud ies have been conducted to solve this issue over the last three decades. In these studies, they either used a permanent magnet (PM), a static current source (SCS), radio frequency (RF) fields or integration of two of these. The PM is a stable and reliable magnetic field source. However, due to the size restriction of the NGT and the WCE, only a small PM can be used. Subsequently, the small size issue causes low power delivery at the larger tracking distance. Also, the PM field is very susceptible to ambient noise, and the PM-based localization is not possible in ap plications requiring robotic actuation. Even though an SCS can be used to replace the permanent magnet, and thus the current level can be varied in relation to the dis tance for optimized power delivery, it requires a relatively high power to generate a higher strength magnetic field. Consequently, a more powerful and larger battery is needed to feed the circuit.Radio frequency field sources require high frequencies to achieve sufficient precision, but these frequencies undergo high attenuation in the body. Therefore, the low-frequency RF field is preferred 1 . In the near-field 2 , plane wave assumption of the far-field fails for localization methods since the waves in this region are spherical. Hence, the wave-front has to be formulated by both the range and the direction of arrival (DOA). The DOA requires the phase difference of neighbouring sensors to be calculated. However, if the operating wavelength is much larger than the distance between the source and the receiver, it is not feasible to compute the phase difference between the neigh bouring sensors. Thus, there are numerous algorithms in the literature to overcome these issues, such as MUSIC or ESPRIT which are either complicated or computa tionally expensive. In RF-based localization, generally the time of arrival (TA), the time differ ence of arrival (TDA), the angle of arrival (AOA) and the received signal strength (RSS) are widely used for localization. However, the TA and TDA require accu rate knowledge of field speed and good time synchronization. It is not possible to accurately know while travelling through the body tissues due to complexity of the tissues. The AOA is also impractical for intra-body applications owing to multiple reflections signal from the tissues, commonly known as the multipath effect. The RSS precision is dependent on good knowledge of power loss in complex body tis sues. Also, the RSS method requires accurate knowledge of the transmitted signal strength. However, the power of transmitted frequencies may vary due to the ca pacitive effect of human tissue on Resonant frequency of source, hence RSS-based techniques prove difficult in practice. Therefore, a novel method of mapping the magnetic field vector in the near field region is proposed. This magnetic field mapping (MFM) uses single-axis coils placed orthogonally with respect to a sensor plane (SP). These single-axis sensors pick up only the orthogonal component of the magnetic field, which varies as a function of the orientation of the source and distance to the source. Thus, using this information, the field strength captured by each sensor is mapped to its correspond ing position on the SP as pixels. Next, these field strengths with known positions are used to detect the location and orientation of the field source relative to the SP. MATLAB and CST Microwave simulation were conducted, and many laboratory experiments were performed, and we show that the novel technique not only over comes the issues faced in the methods mentioned above but also accomplishes an accurate source positioning with a precision of better than ± 0.5 cm in 3-D and orientation with a maximum error of ±5◦
Cal Poly Supermileage Electric Vehicle Drivetrain and Motor Control Design
The Cal Poly Supermileage Vehicle team is a multidisciplinary club that designs and builds high efficiency vehicles to compete internationally at Shell Eco-Marathon (SEM). Cal Poly Supermileage Club has been competing in the internal combustion engine (ICE) category of the competition since 2007. The club has decided it is time to expand their competition goals and enter their first battery electric prototype vehicle. To this end, a yearlong senior design project was presented to this team of engineers giving us the opportunity to design an electric powertrain with a custom motor controller. This system has been integrated into Ventus, the 2017 Supermileage competition car, bringing it back to life as E-Ventus for future competitions.
The scope of this project includes sizing a motor, designing the drivetrain, programing the motor driver, building a custom motor controller, and finally mounting all these components into the chassis. The main considerations in this design are the energy efficiency measured in distance per power used (mi/kWh) and the whole system reliability. Driven train system reliability has been defined as the car starts the first time every time and can complete two competition runs of 6.3 miles each without mechanical or electrical failure. Drivetrain weight target was less than 25 pounds, and the finished system came in at 20 lbs 4 oz. Due to the design difficulties of the custom controller, three iterations were able to be produced by the end of this project, but there will need to be further iterations to complete the controller. Because of these difficulties our sponsor, Will Sirski, and club advisor, Dr. Mello, have agreed that providing the club with a working mechanical powertrain, powertrain data from the club chassis dynamometer using the programmed TI evaluation motor controller board, and providing board layout for the third iteration design for the custom controller satisfy their requirements for this project
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Magnetic DNA detection sensor for point-of-care diagnostics
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonThis thesis focuses on inductive base sensor design at MHz range frequency. The background theory, design, experiments and results for a new magnetic particles sensor is presented. A new magnetic sensor based on a planar coil was investigated for DNA pathogen detection. Change in inductance of the planar coil due to the presence of magnetic particles with varying mass was measured. The experimental set-up consisted of different sized planar coil with associated electronics for inductance measurements. The best sensor performance was accomplished using two different inductors while oscillating at frequencies 2.4MHz using 9.5μH inductor and 7.2MHz with 85μH inductor. The sensor has very large signal to noise ratio (580×103), while the average amount of frequency drift was 0.58. This sensor was tested with various types of magnetic particles. In addition, iron-oxide nanoparticles were synthesized through water in oil microemulsion method and with an average size of 25nm. The best sensitivity achieved for detection of 50μg iron-oxide particles was with the bead size of 10nm. 81Hz frequency shift was attained in regard to that amount of particles. This research shows that increasing the resonance frequency to 7.2MHz can cause the larger output signal difference (frequency shift) in the presence of magnetic particles; however, the sensor stability is the most important factor for determining the detection resolution and sensitivity. The sensitivity is better if the sensor can detect smaller amount of magnetic sample. The results of this research demonstrate that while the sample consists of smaller size particles, the sensor can detect the lower amount of sample. This is due to the heating effect of nanoparticles. On the other hand the sample distance from the sensor has a major impact on the sensitivity too; the shorter the distance, the higher the sensitivity. This technique can potentially be extended to detect several different types of bacterial pathogens and can be modified for multiplex quantitative detection. This sensing technique will be incorporated into a handheld, disposable microfluidic chip for point-of-care diagnostics for sexually transmitted diseases. Key words: Point of care diagnostics, Magnetic particle Detection, Molecular detection, Inductive sensin
NASA Tech Briefs, October 2013
Topics include: A Short-Range Distance Sensor with Exceptional Linearity; Miniature Trace Gas Detector Based on Microfabricated Optical Resonators; Commercial Non-Dispersive Infrared Spectroscopy Sensors for Sub-Ambient Carbon Dioxide Detection; Fast, Large-Area, Wide-Bandgap UV Photodetector for Cherenkov Light Detection; Mission Data System Java Edition Version 7; Adaptive Distributed Environment for Procedure Training (ADEPT); LEGEND, a LEO-to-GEO Environment Debris Model; Electronics/Computers; Millimeter-Wave Localizers for Aircraft-to-Aircraft Approach Navigation; Impedance Discontinuity Reduction Between High-Speed Differential Connectors and PCB Interfaces; SpaceCube Version 1.5; High-Pressure Lightweight Thrusters; Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites; Ambient Dried Aerogels; Applications for Gradient Metal Alloys Fabricated Using Additive Manufacturing; Passivation of Flexible YBCO Superconducting Current Lead With Amorphous SiO2 Layer; Propellant-Flow-Actuated Rocket Engine Igniter; Lightweight Liquid Helium Dewar for High-Altitude Balloon Payloads; Method to Increase Performance of Foil Bearings Through Passive Thermal Management; Unibody Composite Pressurized Structure; JWST Integrated Science Instrument Module Alignment Optimization Tool; Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique; Digitally Calibrated TR Modules Enabling Real-Time Beamforming SweepSAR Architectures; Electro-Optic Time-to-Space Converter for Optical Detector Jitter Mitigation; Partially Transparent Petaled Mask/Occulter for Visible-Range Spectrum; Educational NASA Computational and Scientific Studies (enCOMPASS); Coarse-Grain Bandwidth Estimation Scheme for Large-Scale Network; Detection of Moving Targets Using Soliton Resonance Effect; High-Efficiency Nested Hall Thrusters for Robotic Solar System Exploration; High-Voltage Clock Driver for Photon-Counting CCD Characterization; Development of the Code RITRACKS; and Enabling Microliquid Chromatography by Microbead Packing of Microchannels
Innovative micro-NMR/MRI functionality utilizing flexible electronics and control systems
Das zentrale Thema dieser Arbeit ist die Entwicklung und Integration von flexibler Elektronik für Mikro-Magnetresonanz (MR)-Anwendungen. Zwei wichtige Anwendungen wurden in der Dissertation behandelt; eine Anwendung auf dem Gebiet der Magnetresonanztomographie (MRI) und die andere auf dem Gebiet der Kernspinresonanz (NMR). Die MRI-Anwendung konzentriert sich auf die Lösung der Sicherheits- und Zuverlässigkeitsaspekte von MR-Kathetern. Die NMR-Anwendung stellt einen neuartigen Ansatz zur Steigerung des Durchsatzes bei der NMR-Spektroskopie vor.
Der erste Teil der Dissertation behandelt die verschiedenen Technologien die zur Herstellung flexibler Elektronik auf der Mikroskala entwickelt wurden. Die behandelten MR-Anwendungen erfordern die Herstellung von Induktoren, Kondensatoren und Dioden auf flexiblen Substraten. Die erste Technologie, die im Rahmen der Mikrofabrikation behandelt wird, ist das Aufbringen einer leitfähigen Startschicht auf flexiblen Substraten. Es wurden verschiedene Techniken getestet und verglichen. Die entwickelte Technologie ermöglicht die Herstellung einer mehrschichtigen leitfähigen Struktur auf einem flexiblen Substrat (50 m Dicke), die sich zum Umwickeln eines schlanken Rohres (>0,5 mm Durchmesser) eignet. Die zweite Methode ist der Tintenstrahldruck von Kondensatoren mit hoher Dichte und niedrigem Verlustkoeffizienten. Zwei dielektrische Tinten auf Polymerbasis wurden synthetisiert, durch die Dispersion von TiO und BaTiO in Benzocyclobuten (BCB) Polymer. Die im Tintenstrahldruckverfahren hergestellten Kondensatoren zeigen eine relativ hohe Kapazität pro Flächeneinheit von bis zu 69 pFmm und erreichen dabei einen Qualitätsfaktor (Q) von etwa 100. Außerdem wurde eine Technik für eine tintenstrahlgedruckte gleichrichtende Schottky-Diode entwickelt. Die letzte behandelte Technologie ist die Galvanisierung der leitenden Startschichten. Die Galvanik ist eine gut erforschte Technologie und ein sehr wichtiger Prozess auf dem Gebiet der Mikrofabrikation. Sie ist jedoch in hohem Maße von der Erfahrung des Bedieners abhängig. Darüber hinaus ist eine präzise Steuerung der Galvanikleistung erforderlich, insbesondere bei der Herstellung kleiner Strukturen, wobei sich die Pulsgalvanik als ein Verfahren erwiesen hat, das ein hohes Maß an Kontrolle über die abgeschiedene Struktur bietet. In diesem Zusammenhang wurde eine hochflexible Stromquelle auf Basis einer Mikrocontroller-Einheit entwickelt, um Genauigkeit in die Erstellung optimaler Galvanikrezepte zu bringen. Die Stromquelle wurde auf Basis einer modifizierten Howland-Stromquelle (MHCS) unter Verwendung eines Hochleistungs-Operationsverstärkers (OPAMP) aufgebaut. Die Stromquelle wurde validiert und verifiziert, und ihre hohe Leistungsfähigkeit wurde durch die Durchführung einiger schwieriger Anwendungen demonstriert, von denen die wichtigste die Verbesserung der Haftung der im Tintenstrahldruckverfahren gedruckten Startschicht auf flexiblen Substraten ist.
Der zweite Teil der Dissertation befasst sich mit interventioneller MRT mittels MR-Katheter. MR-Katheter haben potenziell einen erheblichen Einfluss auf den Bereich der minimalinvasiven medizinischen Eingriffe. Implantierte längliche Übertragungsleiter und Detektorspulen wirken wie eine Antenne und koppeln sich an das MR-Hochfrequenz (HF)-Sendefeld an und machen so den Katheter während des Einsatzes in einem MRT-Scanner sichtbar. Durch diese Kopplung können sich die Leiter jedoch erhitzen, was zu einer gefährlichen Erwärmung des Gewebes führt und eine breite Anwendung dieser Technologie bisher verhindert hat. Ein alternativer Ansatz besteht darin, einen Resonator an der Katheterspitze induktive mit einer Oberflächenspule außerhalb des Körpers zu koppeln. Allerdings könnte sich auch dieser Mikroresonator an der Katheterspitze während der Anregungsphase erwärmen. Außerdem ändert sich die Sichtbarkeit der Katheterspitze, wenn sich die axiale Ausrichtung des Katheters während der Bewegung ändert, und kann verloren gehen, wenn die Magnetfelder des drahtlosen Resonators und der externen Spule orthogonal sind. In diesem Beitrag wird die Abstimmkapazität des Mikrodetektors des Katheters drahtlos über eine Impulsfolgensteuerung gesteuert, die an einen HF-Abstimmkreis gesendet wird, der in eine Detektorspule integriert ist. Der integrierte Schaltkreis erzeugt Gleichstrom aus dem übertragenen HF Signal zur Steuerung der Kapazität aus der Ferne, wodurch ein intelligenter eingebetteter abstimmbarer Detektor an der Katheterspitze entsteht. Während der HF-Übertragung erfolgt die Entkopplung durch eine Feinabstimmung der Detektorbetriebsfrequenz weg von der Larmor-Frequenz. Zusätzlich wird ein neuartiges Detektordesign eingeführt, das auf zwei senkrecht ausgerichteten Mikro-Saddle-Spulen basiert, die eine konstante Sichtbarkeit des Katheters für den gesamten Bereich der axialen Ausrichtungen ohne toten Winkel gewährleisten. Das System wurde experimentell in einem 1T MRT-Scanner verifiziert.
Der dritte Teil der Dissertation befasst sich mit dem Durchsatz von NMR-Spektroskopie. Flussbasierte NMR ist eine vielversprechende Technik zur Verbesserung des NMR-Durchsatzes. Eine häufige Herausforderung ist jedoch das relativ große Totvolumen im Schlauch, der den NMR-Detektor speist. In diesem Beitrag wird ein neuartiger Ansatz für vollautomatische NMR-Spektroskopie mit hohem Durchsatz und verbesserter Massensensitivität vorgestellt. Der entwickelte Ansatz wird durch die Nutzung von Mikrofluidik-Technologien in Kombination mit Dünnfilm-Mikro-NMR-Detektoren verwirklicht. Es wurde ein passender NMR-Sensor mit einem mikrofluidischen System entwickelt, das Folgendes umfasst: i) einen Mikro-Sattel-Detektor für die NMR-Spektroskopie und ii) ein Paar Durchflusssensoren, die den NMR-Detektor flankieren und an eine Mikrocontrollereinheit angeschlossen sind. Ein mikrofluidischer Schlauch wird verwendet, um eine Probenserie durch den Sondenkopf zu transportieren, die einzelnen Probenbereiche sind durch eine nicht mischbare Flüssigkeit getrennt, das System erlaubt im Prinzip eine unbegrenzte Anzahl an Proben. Das entwickelte System verfolgt die Position und Geschwindigkeit der Proben in diesem zweiphasigen Fluss und synchronisiert die NMR-Akquisition. Der entwickelte kundenspezifische Sondenkopf ist Plug-and-Play-fähig mit marktüblichen NMR-Systemen. Das System wurde erfolgreich zur Automatisierung von flussbasierten NMR-Messungen in einem 500 MHz NMR-System eingesetzt. Der entwickelte Mikro-NMR-Detektor ermöglicht hochauflösende Spektroskopie mit einer NMR-Empfindlichkeit von 2,18 nmol s bei Betrieb der Durchflusssensoren. Die Durchflusssensoren wiesen eine hohe Empfindlichkeit bis zu einem absoluten Unterschied von 0,2 in der relativen Permittivität auf, was eine Differenzierung zwischen den meisten gängigen Lösungsmitteln ermöglichte. Es wurde gezeigt, dass eine vollautomatische NMR-Spektroskopie von neun verschiedenen 120 L Proben innerhalb von 3,6 min oder effektiv 15,3 s pro Probe erreicht werden konnte
Belle II Technical Design Report
The Belle detector at the KEKB electron-positron collider has collected
almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an
upgrade of KEKB is under construction, to increase the luminosity by two orders
of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2
/s luminosity. To exploit the increased luminosity, an upgrade of the Belle
detector has been proposed. A new international collaboration Belle-II, is
being formed. The Technical Design Report presents physics motivation, basic
methods of the accelerator upgrade, as well as key improvements of the
detector.Comment: Edited by: Z. Dole\v{z}al and S. Un
JUNO Conceptual Design Report
The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine
the neutrino mass hierarchy using an underground liquid scintillator detector.
It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants
in Guangdong, China. The experimental hall, spanning more than 50 meters, is
under a granite mountain of over 700 m overburden. Within six years of running,
the detection of reactor antineutrinos can resolve the neutrino mass hierarchy
at a confidence level of 3-4, and determine neutrino oscillation
parameters , , and to
an accuracy of better than 1%. The JUNO detector can be also used to study
terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard
Model. The central detector contains 20,000 tons liquid scintillator with an
acrylic sphere of 35 m in diameter. 17,000 508-mm diameter PMTs with high
quantum efficiency provide 75% optical coverage. The current choice of
the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO
as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of
detected photoelectrons per MeV is larger than 1,100 and the energy resolution
is expected to be 3% at 1 MeV. The calibration system is designed to deploy
multiple sources to cover the entire energy range of reactor antineutrinos, and
to achieve a full-volume position coverage inside the detector. The veto system
is used for muon detection, muon induced background study and reduction. It
consists of a Water Cherenkov detector and a Top Tracker system. The readout
system, the detector control system and the offline system insure efficient and
stable data acquisition and processing.Comment: 328 pages, 211 figure
Research and Development of an Advanced RFID Security System Based on Locating Multiple Tags
Radio Frequency Identification (RFID) has gained a lot of attention lately with the introduction of RFID tags or inlays for a variety of applications. Most common is location tracking which can further be used for detecting the movements of tags from their original positions. In order to develop a system for finding the change in tag positions, a correct combination of RFID tags and reader is vital. Also, better understanding of challenges facing the RF signal can be productive. Environmental factors, antenna radiation pattern and orientation are some key issues, which can undermine this approach. In this thesis, to address some of the challenges a security algorithm for indoor RFID systems is proposed for detecting the change in the tag positions by finding the change in inter-tag distance. Also, several measures have been used to overcome the random nature of the RF signal. Experiments and evaluation of the above-mentioned methods in real time prove the robustness of the techniques considered for providing security
Scalable Control and Measurement of Gate-Defined Quantum Dot Systems
There is currently a worldwide effort towards the realisation of large-scale quantum computers that exploit quantum phenomena for information processing. While these computing systems could potentially redefine the technological landscape, harnessing quantum effects is challenging due to their inherently fragile nature and the experimentally demanding environments in which they arise. In order for quantum computation to be viable it is first necessary to demonstrate the operation of two-level quantum systems (qubits) which have long coherence times, can be quickly read out, and can be controlled with high fidelity. Focusing on these key requirements, this thesis presents four experiments towards scalable solid state quantum computing using gate-defined quantum dot devices based on gallium arsenide (GaAs) heterostructures. The first experiment investigates a phonon emission process that limits the charge coherence in GaAs and potentially complicates the microwave control of multi-qubit devices. We show that this microwave analogy to Raman spectroscopy can provide a means of detecting the unique phonon spectral density created by a nanoscale device. Experimental results are compared to a theoretical model based on a non-Markovian master equation and approaches to suppressing electron-phonon coupling are discussed. The second experiment demonstrates a technique involving in-situ gate electrodes coupled to lumped-element resonators to provide high-bandwidth dispersive read-out of the state of a double quantum dot. We characterise the charge sensitivity of this method in the few-electron regime and benchmark its performance against quantum point contact charge sensors. The third experiment implements a low-loss, chip-level frequency multiplexing scheme for the readout of scaled-up spin qubit arrays. Dispersive gate-sensing is realised in combination with charge detection based on two radio frequency quantum point contacts to perform multiplexed readout of a double quantum dot in the few-electron regime. Demonstration of a 10-channel multiplexing device is achieved and limitations in scaling spin qubit readout to large numbers using multiplexed channels discussed. The final experiment ties previously presented results together by realising a micro-architecture for controlling and reading out qubits during the execution of a quantum algorithm. The basic principles of this architecture are demonstrated via the manipulation of a semiconductor qubit using control pulses that are cryogenically routed using a high-electron mobility transistor switching matrix controlled by a field programmable gate array. Finally, several technical results are also presented including the development of printed circuit board solutions to allow the high-frequency measurement of nanoscale devices at cryogenic temperatures and the design of on-chip interconnects used to suppress electromagnetic crosstalk in high-density spin qubit device architectures
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