非線形弾性要素による内部力補償に基づく無段階変位–力変換機構の創生 ― 微小操作力で強大な磁気力・把持力・制動力・張力を制御可能とするロボット要素 ―

Tohoku University博士（情報科学）thesi

NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 07)

This bibliography is issued in two sections: Section 1 - Abstracts, and Section 2 - Indexes. This issue of the Abstract Section cites 158 patents and applications for patent introduced into the NASA scientific and technical information system during the period of January 1975 through June 1975. Each entry in the Abstract Section consists of a citation, an abstract, and, in most cases, a key illustration selected from the patent or application for patent. This issue of the Index Section contains entries for 2830 patent and application for patent citations covering the period May 1969 through June 1975. The index section contains five indexes -- subject, inventor, source, number and accession number

Ultracold rubidium and potassium system for atom chip-based microwave and RF potentials

In this dissertation we study the development of microwave and RF near-field potentials for use with atom chip trapped atomic gases. These potentials are inherently spin-dependent, able to target individual spin states simultaneously. In contrast with traditional atom chip potentials, these RF traps can be operated at arbitrary bias magnetic field strengths and thus be combined with magnetic Feshbach resonances. Furthermore, these potentials can strongly suppress the potential roughness that plagues traditional atom chip potentials. We present a dual chamber atom chip apparatus for generating ultracold 87Rb and 39K atomic gases. The apparatus produces quasi-pure Bose-Einstein condensates of 104 87Rb atoms in an atom chip trap that features a dimple and good optical access. We have also demonstrated production of ultracold 39K and subsequent loading into the chip trap. We describe the details of the dual chamber vacuum system, the cooling lasers, the magnetic trap, the multi coil magnetic transport system, and the atom chip. The apparatus is well suited for studies of atom-surface forces, quantum pumping and transport experiments, atom interferometry, novel chip-based traps, and studies of one-dimensional many-body systems

Design and fabrication of a long-life Stirling cycle cooler for space application. Phase 3: Prototype model

A second-generation, Stirling-cycle cryocooler (cryogenic refrigerator) for space applications, with a cooling capacity of 5 watts at 65 K, was recently completed. The refrigerator, called the Prototype Model, was designed with a goal of 5 year life with no degradation in cooling performance. The free displacer and free piston of the refrigerator are driven directly by moving-magnet linear motors with the moving elements supported by active magnetic bearings. The use of clearance seals and the absence of outgassing material in the working volume of the refrigerator enable long-life operation with no deterioration in performance. Fiber-optic sensors detect the radial position of the shafts and provide a control signal for the magnetic bearings. The frequency, phase, stroke, and offset of the compressor and expander are controlled by signals from precision linear position sensors (LVDTs). The vibration generated by the compressor and expander is cancelled by an active counter balance which also uses a moving-magnet linear motor and magnetic bearings. The driving signal for the counter balance is derived from the compressor and expander position sensors which have wide bandwidth for suppression of harmonic vibrations. The efficiency of the three active members, which operate in a resonant mode, is enhanced by a magnetic spring in the expander and by gas springs in the compressor and counterbalance. The cooling was achieved with a total motor input power of 139 watts. The magnetic-bearing stiffness was significantly increased from the first-generation cooler to accommodate shuttle launch vibrations

Nuclear spin noise examined by magnetic resonance force microscopy

Diese Doktorarbeit behandelt Magnet-Resonanz-Kraft-Mikroskopie (MRFM), ein höchst sensitives Verfahren um feinste magnetische Momente, zum Beispiel von Kern- Spins, zu messen. Durch Messen der verschieden Polarisationsarten eines Ensembles magnetischer Momente von 19F Atomkernen wurde die Anzahl gemessener Spins auf ~ 1’000’000 und das Messvolumen auf (26.3 nm)3 bestimmt. Ein solches Ensemble weist zum einen statistische Fluktuationen auf; andererseits folgt es in einem äusseren Magnetfeld einer Boltzmann-Verteilung. Die beiden Polarisationsarten unterschieden sich in ihrer Abhängigkeit von der Teilchenanzahl des Ensembles. Die Varianz der durch die Spins hervorgerufenen Kraft, verhält sich proportional zur Quadratwurzel der Teilchenanzahl. Hingegen ist der absolute Wert der thermischen Polarisierung durch das Magnetfeld linear davon abhängig. Dadurch kann ein Ausdruck für die Teilchenanzahl in Abhängigkeit der beiden gemessenen Kräfte hergeleitet werden, welcher nur die Temperatur und die Stärke des äusseren Magnetfeldes als Messkonstanten beinhaltet. Kenntnisse über die genaue räumliche Verteilung des Magnetfeldes, wie das bei anderen Methoden zutrifft, sind nicht notwendig. Grundsätzlich kann die simple Methode auch direkt auf andere physikalische Untersuchungen angewendet werden, in denen thermische und statistische Polarisierung messbar ist. --- This doctoral thesis deals with magnetic resonance force microscopy (MRFM), a highly sensitive method for measuring finest magnetic moments, for example nuclear spins. By measuring the different polarisation modes of an ensemble of magnetic moments of 19F atomic nuclei, the number of measured spins was determined to be ~ 1,000,000 and the measurement volume to (26.3 nm) 3. On the one hand, such an ensemble has statistical fluctuations; On the other hand, it follows a Boltzmann distribution in an external magnetic field. The two polarisation modes differed in their dependence on the number of particles of the ensemble. The variance of the force evoked by the spins is proportional to the square root of the particle number. The absolute value of the thermal polarisation though depends linearly on the magnetic field. Thereby an expression for the number of particles as a function of the two measured forces can be derived, which only includes the temperature and the strength of the external magnetic field as measuring constants. Knowledge about the exact spatial distribution of the magnetic field is not necessary, as it is in the case of other methods. In principle, the simple method can also be directly applied to other physical investigations in which thermal and statistical polarisation is measurable

Converse Magnetoelectric Resonators for Biomagnetic Field Sensing

Contact-less biomagnetic sensing constitutes the next frontier for advanced healthcare, bringing novel diagnostic abilities using multichannel magnetocardiography (MCG) and magnetoencephalography (MEG) either as a single source of information for rapid patient screening or in combination with established methods such as electrocardiography (ECG) and electroencephalography (EEG) as a source for additional patient information. The combination of established electrical with magnetic patient information potentially leads to novel tools for deep knowledge generation towards pathologies and early prevention of such. The main obstacle towards biomagnetic diagnosis using magnetic imaging techniques is the lack of easy applicable sensor technology which offers extremely low magnetic noise floors; realtime MCG measurements demand for lower than 10 pT/sqrt(Hz), reaching below 100 fT/sqrt(Hz) enables even MEG signal acquisition. Such extremely minute amplitudes that are six to seven orders lower than earth's permanent magnetic field, demand lowest noise sensor technology as the low frequency signal regime below about 1 kHz is strongly affected by omnipresent 1/f-noise. Magnetoelectric (ME) thin film composites consisting of a sputtered piezoelectric (PE) and an amorphous magnetostrictive (MS) layer are usually employed for measurements of magnetic fields passively, i.e. an AC magnetic field directly generates an ME voltage by mechanical coupling of the MS deformation to the PE phase. In order to achieve high field sensitivities, a magnetic bias field is required to operate at the maximum piezomagnetic coefficient of the MS phase. Additionally using mechanical resonances further enhances this direct ME effect size. Despite being able to directly detect very small field amplitudes on the order of 1 pT/sqrt(Hz) for magnetic fields of a frequency exactly matching mechanical resonances comes at the expense of available signal bandwidth, because of rather high resonator quality factors. Strong 1/f noise prevalent in the low frequency regime, makes DC or low frequency magnetic fields tedious to record in that regime using direct ME detection scheme. In the presented work the PE phase is actively excited, thus exploiting the converse ME effect, remedying the shortcomings of the direct effect. ME composites are demonstrated for use as precision sensors, capable of magnetic signal detection in the low frequency, low amplitude biomagnetic regime. The combination of the converse ME effect with high frequency acoustic resonances leads to high piezoelectric stresses generated within the composite, leading to large inverse magnetostriction and thus high sensitivity. A limit of detection (LOD) of 70 pT/sqrt(Hz) at 10 Hz is obtained with composites based on amorphous films of Iron-Cobalt-Silicon-Boron (FeCoSiB). Exploiting advanced magnetoelectric composites based on exchange biased FeCoSiB films (EB-FeCoSiB) LOD values reaching down to 17 pT/sqrt(Hz) at 10 Hz are demonstrated. A trial recording a healthy subjects human MCG signal using an advanced ME composite demonstrates the practical feasibility of biomagnetic measurements and paves the way for routine, realtime biomagnetic measurements in the future.Kontaktlose biomagnetische Diagnostik stellt die nächste Generation von Patientenmonitoring und bildgebender Diagnostik dar, sie ist in der Lage einen schnellen, kontaktlosen Überblick der Vitalfunktionen zu liefern. In Kombination mit etablierten Methoden wie Elektrokardiografie (EKG) und Elektroenzephalografie (EEG) entsteht ein zusätzliches Werkzeug zur Erlangung tieferer Informationen über Pathogenesen und ermöglichen somit eine frühzeitige Erkennung solcher. Die größte technische Hürde der biomagnetischen Diagnose stellt die Entwicklung einer anwenderfreundlichen, wartungsarmen Sensortechnologie dar. Diese Technologie muss über ein extrem niedriges magnetisches Rauschen von kleiner als 10 pT/sqrt(Hz) für Echtzeit Magnetokardiografie (MKG) und bis unter 100 fT/sqrt(Hz) für Magnetoenzephalografie (MEG) verfügen. Derartige Feldstärken von biomagnetischem Niveau sind etwa sechs bis sieben Größenordnungen geringer als das statische Erdmagnetfeld und dabei ebenfalls stets niederfrequent, unterhalb etwa 1 kHz. Damit liegen die relevanten Magnetfelder im Bereich des omnipräsenten 1/f-Rauschens. Magnetoelektrische Dünnschicht-Komposite werden üblicherweise passiv betrieben, indem ein magnetisches Wechselfeld direkt zu einer proportionalen ME-Spannung führt. Dies geschieht mittels magnetostriktiver Dehnung welche durch mechanische Kopplung auf ein Piezoelektrikum übertragen wird und dort eine elektrische Spannung über den direkten piezoelektrischen Effekt erzeugt. Um den größtmöglichen piezomagnetischen Koeffizienten zu erhalten, kommt zusätzlich ein statisches magnetisches Haltefeld zum Einsatz. Durch die Ausnutzung mechanischer Resonanzen wird die Oszillation verstärkt, diese Verstärkung führt in gleichem Maße zu einer Verstärkung des ME-Effekts. Auf diese Weise ist es möglich, magnetische Detektionsgrenzen von etwa 1 pT/sqrt(Hz) zu erreichen, weit im erforderlichen Bereich für Echtzeit MKG Messungen. Diese direkte Ausnutzung mechanischer Resonanzen von hohem Gütefaktor, bringt den wesentlichen Nachteil, dass die Bandbreite des ME Oszillators auf wenige Herz beschränkt ist, welches einer praktischen, breitbandigen Signalerfassung entgegen steht. In dieser Arbeit wird die piezoelektrische Materialphase direkt elektrisch angeregt, es wird der inverse ME-Effekt ausgenutzt. Dieser inverse ME Effekt stellt sich als vorteilhaft im Bezug auf den direkten ME-Effekt heraus, da eine rauscharme Operation ermöglicht wird. Magnetoelektrische Dünnschicht-Komposite werden als Präzisionssensoren zur Detektion von niederfrequenten magnetischen Kleinstsignalen untersucht. Die Kombination aus inversem ME-Effekt und der Ausnutzung hochfrequenter mechanischer Oszillationen führt zu starken mechanischen Verspannungen in der magnetostriktiven Phase und dadurch zu hoher Empfindlichkeit des Sensor-Komposites. Eine Detektionsgrenze von 70 pT/sqrt(Hz) bei einer Frequenz von 10 Hz wird unter Verwendung von magnetostriktiven Einfachlagen erreicht. Die Verwendung fortgeschrittener Mehrlagen-Materialsysteme führt zu einer weiteren Verringerung der Detektionsgrenze auf 17 pT/sqrt(Hz) bei 10 Hz. Schließlich wird in einer Feldstudie am gesunden Probanden eine Machbarkeit zur Detektion humaner MKG Signale gezeigt

Space Mechanisms Lessons Learned Study. Volume 2: Literature Review

Hundreds of satellites have been launched to date. Some have operated extremely well and others have not. In order to learn from past operating experiences, a study was conducted to determine the conditions under which space mechanisms (mechanically moving components) have previously worked or failed. The study consisted of an extensive literature review that included both government contractor reports and technical journals, communication and visits (when necessary) to the various NASA and DOD centers and their designated contractors (this included contact with project managers of current and prior NASA satellite programs as well as their industry counterparts), requests for unpublished information to NASA and industry, and a mail survey designed to acquire specific mechanism experience. The information obtained has been organized into two volumes. Volume 1 provides a summary of the lesson learned, the results of a needs analysis, responses to the mail survey, a listing of experts, a description of some available facilities, and a compilation of references. Volume 2 contains a compilation of the literature review synopsis

Dynamic Characterisation of the Head-Media Interface in Hard Disk Drives using Novel Sensor Systems

Hard disk drives function perfectly satisfactorily when used in a stable environment, but in certain applications they are subjected to shock and vibration. During the work reported in this thesis it has been found that when typical hard disk drives are subjected lo vibration, data transfer failure is found to be significant at frequencies between 440Hz and 700Hz, at an extreme, failing at only Ig of sinusoidal vibration. These failures can largely be attributed to two key components: the suspension arm and the hard disk. At non-critical frequencies of vibration the typical hard disk drive can reliably transfer data whilst subjected to as much as 45g. When transferring data to the drive controller, the drive's operations are controlled and monitored using BIOS commands. Examining the embedded error signals proved that the drive predominantly failed due lo tracking errors. Novel piezo-electric sensors have been developed to measure unobtrusively suspension arm and disk motion, the results from which show the disk to be the most significant failure mechanism, with its First mode of resonance at around 440Hz. The suspension arm movement has been found to be greatest at IkHz. Extensive modelling of the flexure of the disk, clamped and unclamped, has been undertaken using finite element analysis. The theoretical modelling strongly reinforces the empirical results presented in this thesis. If suspension arm movement is not directly coupled with disk movement then a flying height variation is created. This, together with tracking variations, leads to data transfer corruption. This has been found to occur at IkHz and 2kHz. An optical system has been developed and characterised for a novel and inexpensive flying height measurement system using compact disc player technology