Spin tune mapping as a novel tool to probe the spin dynamics in storage rings

Precision experiments, such as the search for electric dipole moments of charged particles using storage rings, demand for an understanding of the spin dynamics with unprecedented accuracy. The ultimate aim is to measure the electric dipole moments with a sensitivity up to 15 orders in magnitude better than the magnetic dipole moment of the stored particles. This formidable task requires an understanding of the background to the signal of the electric dipole from rotations of the spins in the spurious magnetic fields of a storage ring. One of the observables, especially sensitive to the imperfection magnetic fields in the ring is the angular orientation of stable spin axis. Up to now, the stable spin axis has never been determined experimentally, and in addition, the JEDI collaboration for the first time succeeded to quantify the background signals that stem from false rotations of the magnetic dipole moments in the horizontal and longitudinal imperfection magnetic fields of the storage ring. To this end, we developed a new method based on the spin tune response of a machine to artificially applied longitudinal magnetic fields. This novel technique, called \textit{spin tune mapping}, emerges as a very powerful tool to probe the spin dynamics in storage rings. The technique was experimentally tested in 2014 at the cooler synchrotron COSY, and for the first time, the angular orientation of the stable spin axis at two different locations in the ring has been determined to an unprecedented accuracy of better than $2.8\mu$rad.Comment: 32 pages, 15 figures, 7 table

A High-Resolution Combined Scanning Laser- and Widefield Polarizing Microscope for Imaging at Temperatures from 4 K to 300 K

Polarized light microscopy, as a contrast-enhancing technique for optically anisotropic materials, is a method well suited for the investigation of a wide variety of effects in solid-state physics, as for example birefringence in crystals or the magneto-optical Kerr effect (MOKE). We present a microscopy setup that combines a widefield microscope and a confocal scanning laser microscope with polarization-sensitive detectors. By using a high numerical aperture objective, a spatial resolution of about 240 nm at a wavelength of 405 nm is achieved. The sample is mounted on a $^4$He continuous flow cryostat providing a temperature range between 4 K and 300 K, and electromagnets are used to apply magnetic fields of up to 800 mT with variable in-plane orientation and 20 mT with out-of-plane orientation. Typical applications of the polarizing microscope are the imaging of the in-plane and out-of-plane magnetization via the longitudinal and polar MOKE, imaging of magnetic flux structures in superconductors covered with a magneto-optical indicator film via Faraday effect or imaging of structural features, such as twin-walls in tetragonal SrTiO$_3$. The scanning laser microscope furthermore offers the possibility to gain local information on electric transport properties of a sample by detecting the beam-induced voltage change across a current-biased sample. This combination of magnetic, structural and electric imaging capabilities makes the microscope a viable tool for research in the fields of oxide electronics, spintronics, magnetism and superconductivity.Comment: 14 pages, 11 figures. The following article has been accepted by Review of Scientific Instruments. After it is published, it will be found at http://aip.scitation.org/journal/rs

Robust control for an electric power steering system.

The EPS (electric power steering) system is one of the safety-critical systems in modern automotive control system. In this thesis, a dynamic model for an EPS system was derived. And then, new controller architecture with an extra logical controller in the steering feedback loop, called motion controller, was proposed to increase the sensitivity of the control system to the system. Finally, a robust control system was designed based on the proposed EPS model and the new controller architecture. The disturbance signal is the high frequency part of the torque from road to the rack and pinion. The disturbance can be modeled as bounded noise or white noise. Hinfinity technology is often used to attenuate the bounded noise. The control design was divided into two stages. The first stage is to design a PI motor controller to increase the reaction speed. The next stage is to design an Hinfinity motion controller based on the frequency character of the disturbance signal. Simulations were carried out to demonstrate the controller\u27s performance and robustness characteristics for both bounded noise and white noise. (Abstract shortened by UMI.)Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2004 .L552. Source: Masters Abstracts International, Volume: 43-05, page: 1780. Adviser: X. Chen. Thesis (M.A.Sc.)--University of Windsor (Canada), 2004

Autonomous Vehicle Coordination with Wireless Sensor and Actuator Networks

A coordinated team of mobile wireless sensor and actuator nodes can bring numerous benefits for various applications in the field of cooperative surveillance, mapping unknown areas, disaster management, automated highway and space exploration. This article explores the idea of mobile nodes using vehicles on wheels, augmented with wireless, sensing, and control capabilities. One of the vehicles acts as a leader, being remotely driven by the user, the others represent the followers. Each vehicle has a low-power wireless sensor node attached, featuring a 3D accelerometer and a magnetic compass. Speed and orientation are computed in real time using inertial navigation techniques. The leader periodically transmits these measures to the followers, which implement a lightweight fuzzy logic controller for imitating the leader's movement pattern. We report in detail on all development phases, covering design, simulation, controller tuning, inertial sensor evaluation, calibration, scheduling, fixed-point computation, debugging, benchmarking, field experiments, and lessons learned

Redução do tempo de retardo dos pares de entrada ao motor elétrico do sistema EPS

An Electric Power Steering (EPS) system will be considered in this report. The electric power steering systems have some benefits over old and traditional hydraulic power steering systems in engine efficiency, space efficiency, and environmental compatibility. According to this system, the researchers will study an electrohydraulic steering system. In this system, all functional components have been removed in the previous systems and have been made up of an electric motor, speed sensors, torque and electrical control unit. The simplest difference between these systems and last systems is to lower the weight of the vehicle than to the hydraulic systems. The simulation results show that the torque of the motor in the two simulation modes has the same behavior as the input torque, but this torque has a time delay compared to the input. In the vehicle's steering system, it is necessary to minimize the torque associated with the motor to reduce damage to the engine and system, which is also appropriate in simulation results, so that the wave can be ignored. Comparison of simulation results showed that the control system function is much more convenient than when the torque is acted stepwise and suddenly when the input torque is inputted to the system.En este informe se considerará un sistema de dirección asistida eléctrica (EPS). Los sistemas de dirección asistida eléctrica tienen algunos beneficios sobre los sistemas de dirección asistida hidráulicos antiguos y tradicionales en cuanto a la eficiencia del motor, la eficiencia del espacio y la compatibilidad ambiental. De acuerdo con este sistema, los investigadores estudiarán un sistema de dirección electrohidráulica. En este sistema, todos los componentes funcionales se han eliminado de los sistemas anteriores y se han formado por un motor eléctrico, sensores de velocidad, par y unidad de control eléctrico. La diferencia más simple entre estos sistemas y los últimos sistemas es reducir el peso del vehículo que los sistemas hidráulicos. Los resultados de la simulación muestran que el par del motor en los dos modos de simulación tiene el mismo comportamiento que el par de entrada, pero este par tiene un retardo de tiempo en comparación con la entrada. En el sistema de dirección del vehículo, es necesario minimizar el par de torsión asociado con el motor para reducir el daño al motor y al sistema, lo que también es apropiado en los resultados de la simulación, para que la onda se pueda ignorar. La comparación de los resultados de la simulación mostró que la función del sistema de control es mucho más conveniente que cuando el par se actúa paso a paso y repentinamente cuando el par de entrada se ingresa al sistema.Um sistema de direção assistida elétrica (EPS) será considerado neste relatório. Os sistemas de direção elétrica têm alguns benefícios em relação aos antigos e tradicionais sistemas de direção hidráulica na eficiência do motor, eficiência de espaço e compatibilidade ambiental. Segundo este sistema, os pesquisadores estudarão um sistema de direção eletro-hidráulico. Neste sistema, todos os componentes funcionais foram removidos nos sistemas anteriores e foram constituídos por um motor elétrico, sensores de velocidade, torque e unidade de controle elétrico. A diferença mais simples entre esses sistemas e os últimos sistemas é diminuir o peso do veículo em relação aos sistemas hidráulicos. Os resultados da simulação mostram que o torque do motor nos dois modos de simulação tem o mesmo comportamento que o torque de entrada, mas esse torque tem um atraso de tempo comparado à entrada. No sistema de direção do veículo, é necessário minimizar o torque associado ao motor para reduzir os danos ao motor e ao sistema, o que também é apropriado nos resultados da simulação, para que a onda possa ser ignorada. A comparação dos resultados da simulação mostrou que a função do sistema de controle é muito mais conveniente do que quando o torque é acionado em etapas e subitamente quando o torque de entrada é introduzido no sistema

Lunar articulated remote transportation system

The students of the Florida A&M/Florida State University College of Engineering continued their design from 1988 to 1989 on a first generation lunar transportation vehicle for use on the surface of the Moon between the years 2010 and 2020. Attention is focused on specific design details on all components of the Lunar Articulated Remote Transportation System (Lunar ARTS). The Lunar ARTS will be a three-cart, six-wheeled articulated vehicle. Its purpose will be the transportation of astronauts and/or materials for excavation purposes at a short distance from the base (37.5 km). The power system includes fuel cells for both the primary system and the back-up system. The vehicle has the option of being operated in a manned or unmanned mode. The unmanned mode includes stereo imaging with signal processing for navigation. For manned missions the display console is a digital readout displayed on the inside of the astronaut's helmet. A microprocessor is also on board the vehicle. Other components of the vehicle include a double wishbone/flexible hemispherical wheel suspension; chassis; a steering system; motors; seat retraints; heat rejection systems; solar flare protection; dust protection; and meteoroid protection. A one-quarter scale dynamic model has been built to study the dynamic behavior of the vehicle. The dynamic model closely captures the mechanical and electrical details of the total design

Explicit parallel co-simulation approach: analysis and improved coupling method based on H-infinity synthesis

Co-simulation is widely used in the industry for the simulation of multidomain systems. Because the coupling variables cannot be communicated continuously, the co-simulation results can be unstable and inaccurate, especially when an explicit parallel approach is applied. To address this issue, new coupling methods to improve the stability and accuracy have been developed in recent years. However, the assessment of their performance is sometimes not straightforward or is even impossible owing to the case-dependent effect. The selection of the coupling method and its tuning cannot be performed before running the co-simulation, especially with a time-varying system. In this work, the co-simulation system is analyzed in the frequency domain as a sampled-data interconnection. Then a new coupling method based on the H-infinity synthesis is developed. The method intends to reconstruct the coupling variable by adding a compensator and smoother at the interface and to minimize the error from the sample-hold process. A convergence analysis in the frequency domain shows that the coupling error can be reduced in a wide frequency range, which implies good robustness. The new method is verified using two co-simulation cases. The first case is a dual mass–spring–damper system with random parameters and the second case is a co-simulation of a multibody dynamic (MBD) vehicle model and an electric power-assisted steering (EPAS) system model. Experimental results show that the method can improve the stability and accuracy, which enables a larger communication step to speed up the explicit parallel co-simulation

Robust Control Techniques for State Tracking in the Presence of Variable Time Delays

In this paper, a distributed driver-in-the-Ioop and hardware-in-the-Ioop simulator is described with a driver on a motion simulator at the U.S. Army TARDEC Ground Vehicle Simulation Laboratory (GVSL). Realistic power system response is achieved by linking the driver in the GVSL with a full-sized hybrid electric power system located 2,450 miles away at the TARDEC Power and Energy Systems Integration Laboratory (P&E SIL), which is developed and maintained by Science Applications International Corporation (SAIC). The goal is to close the loop between the GVSL and P&E SIL over the Internet to provide a realistic driving experience in addition to realistic power system results. In order to preserve a valid and safe hardware-in-the-Ioop experiment, the states of the GVSL must track the states of the P&E SIL. In a distributed control system utilizing the open Internet, the communications channel is a primary source of uncertainty and delay that can degrade the overall system performance and stability. The presence of a cross-country network delay and the unavoidable differences between the P&E SIL hardware and GVSL model will cause the GVSL states and P&E SIL states to diverge without any additional action. Thus, two robust strategies for state convergence are developed and presented in this paper. The first strategy is a non-linear Sliding Mode control scheme. The second strategy is an H-infinity control scheme. Both schemes are implemented in simulation, and both schemes show promising results for state convergence in the presence of variable cross-country time delays