Concept, modeling, and performance prediction of a low-cost, large deformable mirror

While it is attractive to integrate a deformable mirror (DM) for adaptive optics (AO) into the telescope itself rather than using relay optics within an instrument, the resulting large DM can be expensive, particularly for extremely large telescopes. A low-cost approach for building a large DM is to use voice-coil actuators connected to the back of the DM through suction cups. Use of such inexpensive voice-coil actuators leads to a poorly damped system with many structural modes within the desired bandwidth. Control of the mirror dynamics using electro-mechanical sensors is thus required for integration within an AO system. We introduce a distributed control approach, and we show that the “inner” back sensor control loop does not need to function at low frequencies, leading to significant cost reduction for the sensors. Incorporating realistic models of low-cost actuators and sensors together with an atmospheric seeing model, we demonstrate that the low-cost mirror strategy is feasible within a closed-loop AO system

Suppressing low-order eigenmodes with local control for deformable mirrors

To improve the mechanical characteristics of actively controlled continuous faceplate deformable mirrors in adaptive optics, a strategy for reducing crosstalk between adjacent actuators and for suppressing low-order eigenmodes is proposed. The strategy can be seen as extending Saint-Venant’s principle beyond the static case, for small local families of actuators. An analytic model is presented, from which we show the feasibility of the local control. Also, we demonstrate how eigenmodes and eigenfrequencies are affected by mirror parameters, such as thickness, diameter, Young’s modulus, Poisson’s ratio, and density. This analysis is used to evaluate the design strategy for a large deformable mirror, and how many actuators are needed within a family

The Taarblin experience : a planned approach to soil conservation

Many farms in Western Australia were cleared and developed before there was a full and clear understanding of the effects of bush clearing - that is salinization of soil and water supplies, wind and water erosion, waterlogging and soil structure decline. The productive capacity and inherent problems of the different soil types was also largely unknown. Modern-day Conservation Farm Planning aims to provide a blue-print for the redevelopment of properties to ensure long term soil fertility, to prevent soil erosion and degradation by waterlogging and salinity. It also provides for a spread of reliable stock watering points and more efficient management by convenient working patterns and access for stock and vehicle movement. To a very large extent the farmer himself is involved in preparing the Conservation Farm Plan but he can obtain advice on the technical aspects of conservation land management from Advisers and Technical Officers at his local office of the Western Australian Department of Agriculture; thus preparation of a Conservation Farm Plan is a joint effort between the farmer and a Soil Conservation Officer.https://researchlibrary.agric.wa.gov.au/bulletins/1104/thumbnail.jp

New trends In urban and regional governance in the Pearl River Region

Parallel Session 3: 3.1 UrbanizationThe impacts of globalization and the collapse of the global credit market, along with the shift in economic production, forced economic restructurings, are greatly affecting and stimulating the trajectories of China's economic developments. Under these circumstances, urban and regional governance is changing rapidly with complicated relations between government, the economy and the emerging civil society. The Outline of the Plan for the Reform and Development of the PRD 2008-2020 and other national plans for revitalizing key industries provide impetus for possible mid-term regional economic development and transformation in south China.published_or_final_versio

Distributed Control of Large Deformable Mirrors

While it is attractive to integrate a deformable mirror (DM) for adaptive optics (AO) into the telescope itself rather than using relay optics within an instrument, the resulting large DM can be expensive, particularly for extremely large telescopes. A low-cost approach for building a large DM is to use voice-coil actuators, and rely on feedback from mechanical sensors to improve the dynamic response of the mirror sufficiently so that it can be used in a standard AO control system. The use of inexpensive voice-coil actuators results in many lightly- damped structural resonances within the desired control bandwidth. We present a robust control approach for this problem, and demonstrate performance in a closed-loop AO simulation, incorporating realistic models of low-cost actuators and sensors. The first contribution is to demonstrate that high-bandwidth active damping can be robustly implemented even with non-collocated sensors, by relying on the "acoustic limit" of the structure where the modal bandwidth exceeds the modal spacing. Next we introduce a novel local control approach, which significantly improves the high spatial frequency performance relative to collocated position control, but without the robustness challenges associated with a global control approach. The combination of these "inner" control loops results in DM command response that is demonstrated to be sufficient for integration within an AO system

Utility Trombone Playing: A Practical Method for Students to Achieve Mastery of Alto, Tenor and Bass Trombone

With the importance of versatility in freelance work in the world of trombone performance, along with increased competition for that work, the need for players to play alto, tenor, and bass trombones to a high level of proficiency has become more and more crucial. This, coupled with the growing number of orchestras looking to hire musicians who are highly competent on all three instruments means that university professors need to be able to teach all three instruments. This evolution of the job market is driving a need for pedagogical material that is specifically designed to address the unique challenges of practicing and performing at a professional level on the main three instruments in the trombone family. As of the time of writing, this material simply does not exist. This project aims to fill that instructional gap. It gives students and teachers a resource that outlines an approach for a four-year undergraduate course of study that allows for the development of the playing of each of the trombones individually and collectively, utilizing the strengths of one instrument to develop the other two. It will also allow for the exploration of the technical challenges that arise when playing and changing between instruments. This four-year course of study combined with a clear explanation of numerous routines can be used from early in a student's development. It can be tailored to their specific needs and will give any teacher and student a comprehensive and holistic method for the acquisition of the skills needed to become a successful utility trombonist

Dissipative Dynamics of Matter Wave Soliton in Nonlinear Optical Lattice

Dynamics and stability of solitons in two-dimensional (2D) Bose-Einstein condensates (BEC), with low-dimensional (1D) conservative plus dissipative nonlinear optical lattices are investigated. In the case of focusing media (with attractive atomic systems) the collapse of the wave packet is arrested by the dissipative periodic nonlinearity. The adiabatic variation of the background scattering length leads to metastable matter-wave solitons. When the atom feeding mechanism is used, a dissipative soliton can exist in focusing 2D media with 1D periodic nonlinearity. In the defocusing media (repulsive BEC case) with harmonic trap in one dimension and one dimensional nonlinear optical lattice in other direction, the stable soliton can exist. This prediction of variational approach is confirmed by the full numerical simulation of 2D Gross-Pitaevskii equation.Comment: 9 pages, 8 figure

資本会計における所有者の限定と利益計算：FASB 基本所有アプローチの争点

１．はじめに ２．負債と株主持分の区分問題の経緯 ３．基本所有アプローチの争点 ４．資本利益計算にかかる基本所有アプローチの貢献と課題 ５．おわり

Calore Jim PSEG Energy Resources and Trade LLC Transmission Owner

koster joanne FirstEnergy Control Area Transmission Owne