Control Mechanism and Experimental Study on Electric Drive Seed Metering Device of Air Suction Seeder

Under the condition of high-speed operation, the traditional mechanical seeder is easy to cause problems such as the drop of the qualified rate of sowing, the increase in the rate of missing sowing and the low precision of adjusting the grain distance, which seriously affects the sowing precision and efficiency. In this paper, a brushless DC motor sliding film variable structure control system is designed for the air-suction corn seeder, so as to realize the precise control of the rotation speed and the seed metering amount of the seed metering disc. The experimental results show that the faster the operation speed of the electrically driven air-suction seed metering device, the greater the standard deviation of sowing distance. The qualified rate of seeding, average spacing, standard deviation distribution and coefficient of variation of the electric seeding device are better than those of the mechanical seeding device

Magnetics in Smart Grid

This journal issue contain selected papers from the Asia-Pacific Data Storage Conference (APDSC'13)A revolution in power transmission and distribution, driven by environmental and economic considerations, is occurring all over the world. This revolution is spearheaded by the development of the smart grid. The smart grid is bringing profound change to both the power systems and many related industries. This paper reviews the development of the smart grid and its correlation with magnetics, including electromagnetic compatibility issue, magnetic-field-based measurement/monitoring, and magnetic energy storage/conversion. The challenge to the field of magnetics and the usage of the cutting edge magnetics technology in the development of the smart grid are discussed. This paper enables researchers in the magnetics community to be acquainted with the progress in the smart grid and inspires innovative applications of state-of-the-art magnetics technologies in the smart grid.published_or_final_versio

Parallel manipulation of individual magnetic microbeads for lab-on-a-chip applications

Many scientists and engineers are turning to lab-on-a-chip systems for cheaper and high throughput analysis of chemical reactions and biomolecular interactions. In this work, we developed several lab-on-a-chip modules based on novel manipulations of individual microbeads inside microchannels. The first manipulation method employs arrays of soft ferromagnetic patterns fabricated inside a microfluidic channel and subjected to an external rotating magnetic field. We demonstrated that the system can be used to assemble individual beads (1-3µm) from a flow of suspended beads into a regular array on the chip, hence improving the integrated electrochemical detection of biomolecules bound to the bead surface. In addition, the microbeads can follow the external magnet rotating at very high speeds and simultaneously orbit around individual soft magnets on the chip. We employed this manipulation mode for efficient sample mixing in continuous microflow. Furthermore, we discovered a simple but effective way of transporting the microbeads on-chip in the rotating field. Selective transport of microbeads with different size was also realized, providing a platform for effective sample separation on a chip. The second manipulation method integrates magnetic and dielectrophoretic manipulations of the same microbeads. The device combines tapered conducting wires and fingered electrodes to generate desirable magnetic and electric fields, respectively. By externally programming the magnetic attraction and dielectrophoretic repulsion forces, out-of-plane oscillation of the microbeads across the channel height was realized. Furthermore, we demonstrated the tweezing of microbeads in liquid with high spatial resolutions by fine-tuning the net force from magnetic attraction and dielectrophoretic repulsion of the beads. The high-resolution control of the out-of-plane motion of the microbeads has led to the invention of massively parallel biomolecular tweezers.Ph.D.Committee Chair: Hesketh, Peter; Committee Member: Allen, Mark; Committee Member: Degertekin, Levent; Committee Member: Lu, Hang; Committee Member: Yoda, Minam

Novel Lorentz Force Velocimetry system based on bulk high-temperature superconductors

Die Lorentzkraftanometrie (LKA) ist eine Technik zur Messung der Geschwindigkeit von elektrisch leitfähigen Flüssigkeiten. Sie ist eine nicht-invasive Messtechnik, die besonders vorteilhaft für heiße, opake und aggressive Elektrolyte ist. Die LKA wurde für Salzwasser als Modellelektrolyt erfolgreich mit Dauermagnetanordnungen (DM) ohne magnetischen Rückschluss, aber mit gezielter Flussführung (Halbach-Array) und hochpräzisen Kraftmesssytemen (KMS) auf Basis der interferometrischen Messung der Auslenkung des Magnetsystems und der elektromagnetischen Kompensation der Auslenkung demonstriert. Um die LKA für schwach leitfähige Elektrolyte zu erweitern, ist eine Magnetfelderzeugung von > 1 T erforderlich. Ein Hochtemperatursupraleiter-Bulk (Bulk-HTS) kann ein Magnetfeld von mehreren Tesla erzeugen und somit die LKA-Leistung deutlich verbessern und die bisher genutzten DM ersetzen. Diese Arbeit zielt deshalb darauf ab, Bulk-HTS's in der LKA unter Berücksichtigung der kritischen Verbindungen zwischen der Funktionalität von Bulk-HTS's und dem KMS einzusetzen und ein LKA-System mit Bulk-HTS's zu entwerfen, herzustellen und zu testen. Die Ergebnisse wurden für die Entwicklung eines neuartigen LKA-System auf Basis eines Bulk-HTS als Magnetfeldquelle und einer Torsionswaage als Kraftmesssystem genutzt. Dieses System - Superconducting High-precision Lorentz Force Measurement System (Super-LOFOS) - wurde dann erfolgreich aufgebaut und getestet. Bei Kühlung mit flüssigem Stickstoff bzw. Helium werden auf der Stirnfläche des Super-LOFOS magnetische Flußdichten von B_T = 100 mT bzw. B_T = 1,2 T erzeugt. Damit erweitert die vorliegende Arbeit die Einsetzbarkeit der LKA für gering elektrisch leitende und langsam strömende Fluide auf (σ · u) = 1-10) S s⁻¹, sowie macht hochpräzise Kraftmessungen bis 1 nN unter kryogenen Bedingungen möglich. Darüber hinaus stellt das entwickelte Messsystem Super-LOFOS einen tragbaren Magnetfeldgenerator dar, der für NMR- und MRT-Technologien, Drug Targeting, und magnetische Trennungsverfahren einsetzbar ist.Lorentz Force Velocimentry (LFV) is a technique to measure the velocity of electrically conducting fluids. The advantage of LFV is that this non-invasive measurement method is particularly well suited for use on hot and opaque liquids as well as aggressive electrolytes. LFV for saline water - the model electrolyte - was successfully demonstrated using permanent magnet (PM) configurations without an iron yoke magnetic flux guide, but with targeted magnetic flux guidance (Halbach-array) and a high-precision force measurement system (FMS) based on interferometric measurements of magnet system (MS) deflection and electromagnetic force compensation balance. To extend the LFV for weakly conductive electrolytes, it is required to generate a magnetic field over 1 T. A bulk high-temperature superconsuctors (HTSs) can generate the magnetic field of several teslas and therefore can significantly enhance LFV performance, replacing previously used PM. This thesis aims to integrate the bulk HTS into the LFV considering the critical links between the functionality of bulk HTS and the FMS with the end goal to design, manufacture, and test a novel LFV system using bulk HTS. The obtained results were used to develop a novel LFV system using bulk HTS as magnetic field generator and a torsion balance as FMS. This LFV system - Superconducting High-precision Lorentz Force Measurement System (Super-LOFOS) - was then successfully designed, manufactured, and tested. Using nitrogen and helium cryogenic liquids, the magnetic flux density of B_T = 100 mT and B_T = 1.2 T were generated at the Super-LOFOS front surface, respectively. This thesis also extends the LFV applicability for weakly-conducting and slow-flowing electrolytes (σ · u) = (1-10) S s⁻¹ as well as enabling high-precision force measurements up to 1 nN under cryogenic temperatures. Furthermore, the developed Super-LOFOS provides a portable magnetic field generator, which can be used for NMR and MRI technologies, magnetic separation, and drug targeting applications

Local Lorentz Force Velocimetry for liquid metal duct flows

Metallschmelzen sind heiß, chemisch aggressiv und undurchsichtig, und damit für konventionelle Strömungsmessgeräte unzugänglich. Die neu entwickelte Lorentzkraft-Anemometrie (LKA oder LFV) umgeht diese Probleme, da sie die berührungslose Messung von Strömungsgeschwindigkeiten in elektrisch leitfähigen Flüssigkeiten mit Hilfe von Magnetfeldern erlaubt. Dabei ist die Wechselwirkung zwischen dem eingesetzten Permanentmagneten und der leitfähigen, bewegten Flüssigkeit ein Maß für die Geschwindigkeit der Metallschmelze. Die Standard-LKA wurde bereits ausgiebig untersucht und wird für den industriellen Alltag entwickelt. Bisher beschränkte sich die LKA auf Volumenstrommessungen; Störungen des Geschwindigkeitfeldes, wie sie nach Knicken im Strömungskanal oder durch Ablagerungen an der Kanalwand entstehen, konnten bislang nicht aufgelöst werden. Diese Lücke wird mit der vorliegenden Arbeit geschlossen und die Standard-LKA um die Möglichkeit der lokal aufgelösten Geschwindigkeitsmessung erweitert. Insbesondere wird belegt, dass lokale Messungen mit der LKA trotz der prinzipiell unendlichen Ausdehnung des Magnetfeldes möglich sind.Zu diesem Zweck werden verschiedene Experimente durchgeführt. In allen wird ein Lorentzkraft-Anenometer (LFF) mit einem Permanentmagneten ausgestattet, der deutlich kleiner ist als die typischen Längenskalen der zu untersuchenden Strömung. Das Arbeitsmedium ist die bei Raumtemperatur flüssige Legierung GaInSn.Mit einem Vorexperiment wird gezeigt, dass die winzigen erzeugten Kräfte tatsächlich aufgelöst werden können. Die Erkenntnisse aus dem vorläufigen Aufbau flossen in den Aufbau des Hauptexperiments, das aus einem Kanal mit quadratischem Querschnitt und einem interferenzoptischen Kraftmesssystem besteht. Die erhaltenen Kraftprofile dienen der Validierung von zukünftigen numerischen Simulationen. Wichtiger ist jedoch die Charakterisierung der Anwendungsbereiche des lokalen LFF mit Hilfe bestimmter Modifikationen des Strömungsprofils: (1) Laminare Strömungen können von turbulenten Strömungen unterschieden werden. (2) Das Maximum der mittleren Strömung kann lokalisiert werden. (3) Zwei benachbarte Strahlen können trotz des prinzipiell unendlichen Magnetfelds voneinander unterschieden werden. (4) Die zeitliche Auflösung ist ausreichend um Bereiche besonders hoher Turbulenz und Wirbelablösung zu identifizierern.Metal melts are typically hot, aggressive, and opaque, and are therefore inaccessible to conventional flow measurement techniques. Lately, a non-contact technique has been developed, termed Lorentz Force Velocimetry (LFV), which is based on the interaction of an electrically conductive moving fluid with a magnetic field. The magnet providing the field experiences a Lorentz force which can be detected and depends on the velocity of the moving metal.Standard LFV has been studied in detail and is now operational under industrial conditions. However well working, the standard LFV is designed for volume flux measurements with large magnet systems and therefore cannot resolve local velocity disturbances as might be caused by sharp bends in the flow or deposits on the pipe wall. The thesis at hand bridges that gap and extends Lorentz Force Velocimetry to the locally resolved measurement of flow velocities with a small magnet. It shows that the claim of local measurements is appropriate although the magnetic field employed is generally unbounded.Several experiments are performed to achieve this goal. All have in common that a Lorentz Force Flow meter (LFF) is equipped with a permanent magnet whose dimensions are significantly smaller than that of the duct flow under investigation. The working fluid is the eutectic alloy GaInSn which is liquid at room temperature. A first preliminary setup uses a rectangular duct and a strain gauge-based force measurement system to prove that the principle of local LFV is feasible and the tiny forces involved can indeed be detected. The results from this setup have been used to design the more sophisticated main setup with a square duct and an interference optical force measurement system.The obtained force profiles provide a database for validating future numerical simulations. More importantly, certain modifications to the flow help characterize the scope of the local LFF: (1) A laminar flow can reliably be distinguished from a turbulent flow. (2) The maximum of the mean flow can be located. (3) Two close jets can be readily distinguished despite the generally infinitely extending magnetic field. (4) Temporal resolution is sufficient to identify regions of particularly high turbulence and vortex shedding

Investigations into pulsed ultra-high magnetic field single-turn coil systems and [theta]-pinch electromagnetically-driven flux compression devices

Magnetic flux densities exceeding 100 T are termed 'ultrahigh' magnetic flux densities and are necessarily developed using pulsed energies. Two particular laboratory techniques are commonly used to produce magnetic fields of this size; the single turn coil (STC) technique and the electromagnetically driven flux compression (EMFC) technique. Over recent years there has been a strong drive to improve both of these systems and to develop them further. This has primarily been achieved by analytical simulation as well as by innovative design solutions. This thesis investigates both techniques, and in particular details the development of an accurate finite element model used in predicting the behaviour of STC systems as well as detailing experimental advances made using a-pinch EMFC systems, including in particular the use of an insulator–metallic phase transition cascade

Agricultural Structures and Mechanization

In our globalized world, the need to produce quality and safe food has increased exponentially in recent decades to meet the growing demands of the world population. This expectation is being met by acting at multiple levels, but mainly through the introduction of new technologies in the agricultural and agri-food sectors. In this context, agricultural, livestock, agro-industrial buildings, and agrarian infrastructure are being built on the basis of a sophisticated design that integrates environmental, landscape, and occupational safety, new construction materials, new facilities, and mechanization with state-of-the-art automatic systems, using calculation models and computer programs. It is necessary to promote research and dissemination of results in the field of mechanization and agricultural structures, specifically with regard to farm building and rural landscape, land and water use and environment, power and machinery, information systems and precision farming, processing and post-harvest technology and logistics, energy and non-food production technology, systems engineering and management, and fruit and vegetable cultivation systems. This Special Issue focuses on the role that mechanization and agricultural structures play in the production of high-quality food and continuously over time. For this reason, it publishes highly interdisciplinary quality studies from disparate research fields including agriculture, engineering design, calculation and modeling, landscaping, environmentalism, and even ergonomics and occupational risk prevention

Smart Screening System (S3) In Taconite

The conventional screening machines used in processing plants have had undesirable high noise and vibration levels. They also have had unsatisfactorily low screening efficiency, high energy consumption, high maintenance cost, low productivity, and poor worker safety. These conventional vibrating machines have been used in almost every processing plant. Most of the current material separation technology uses heavy and inefficient electric motors with an unbalanced rotating mass to generate the shaking. In addition to being excessively noisy, inefficient, and high-maintenance, these vibrating machines are often the bottleneck in the entire process. Furthermore, these motors, along with the vibrating machines and supporting structure, shake other machines and structures in the vicinity. The latter increases maintenance costs while reducing worker health and safety. The conventional vibrating fine screens at taconite processing plants have had the same problems as those listed above. This has resulted in lower screening efficiency, higher energy and maintenance cost, and lower productivity and workers safety concerns. The focus of this work is on the design of a high performance screening machine suitable for taconite processing plants. SmartScreens{trademark} technology uses miniaturized motors, based on smart materials, to generate the shaking. The underlying technologies are Energy Flow Control{trademark} and Vibration Control by Confinement{trademark}. These concepts are used to direct energy flow and confine energy efficiently and effectively to the screen function. The SmartScreens{trademark} technology addresses problems related to noise and vibration, screening efficiency, productivity, and maintenance cost and worker safety. Successful development of SmartScreens{trademark} technology will bring drastic changes to the screening and physical separation industry. The final designs for key components of the SmartScreens{trademark} have been developed. The key components include smart motor and associated electronics, resonators, and supporting structural elements. It is shown that the smart motors have an acceptable life and performance. Resonator (or motion amplifier) designs are selected based on the final system requirement and vibration characteristics. All the components for a fully functional prototype are fabricated and have been tested

NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 27)

Abstracts are provided for 92 patents and patent applications entered into the NASA scientific and technical information system during the period January 1985 through June 1985. Each entry consist of a citation, and abstract, and in most cases, a key illustration selected from the patent or patent application