Wind turbine response to parameter variation of analytic inflow vortices

As larger wind turbines are placed on taller towers, rotors frequently operate in atmospheric conditions that support organized, coherent turbulent structures. It is hypothesized that these structures have a detrimental impact on the blade fatigue life experienced by the wind turbine. These structures are extremely difficult to identify with sophisticated anemometry such as ultrasonic anemometers. This study was performed to identify the vortex characteristics that contribute to high‐amplitude cyclic blade loads, assuming that these vortices exist under certain atmospheric conditions. This study does not attempt to demonstrate the existence of these coherent turbulent structures. In order to ascertain the idealized worst‐case scenario for vortical inflow structures impinging on a wind turbine rotor, we created a simple, analytic vortex model. The Rankine vortex model assumes that the vortex core undergoes solid body rotation to avoid a singularity at the vortex centre and is surrounded by a two‐dimensional potential flow field. Using the wind turbine as a sensor and the FAST wind turbine dynamics code with limited degrees of freedom, we determined the aerodynamic loads imparted to the wind turbine by the vortex structure. We varied the size, strength, rotational direction, plane of rotation, and location of the vortex over a wide range of operating parameters. We identified the vortex conformation with the most significant effect on the blade root bending moment cyclic amplitude. Vortices with radii on the scale of the rotor diameter or smaller caused blade root bending moment cyclic amplitudes that contribute to high damage density. The rotational orientation, clockwise or counter‐clockwise, produces little difference in the bending moment response. Vortices in the XZ plane produce bending moment amplitudes significantly greater than vortices in the YZ plane. Published in 2005 by John Wiley & Sons, Ltd.     

A Simple Quasi-2D Numerical Model of a Thermogage Furnace

A simple quasi-2D model for the temperature distribution in a graphite tube furnace is presented. The model is used to estimate the temperature gradients in the furnace at temperatures above which contact sensors can be used, and to assist in the redesign of the furnace heater element to improve the temperature gradients. The Thermogage graphite tube furnace is commonly used in many NMIs as a blackbody source for radiation thermometer calibration and as a spectral irradiance standard. Although the design is robust, easy to operate and can change temperature rapidly, it is limited by its effective emissivity of typically 99.5–99.8%. At NMIA, the temperature gradient along the tube is assessed using thermocouples up to about 1,500°C, and the blackbody emissivity is calculated from this. However, at higher operating temperatures (up to 2,900°C), it is impractical to measure the gradient, and we propose to numerically model the temperature distributions used to calculate emissivity. In another paper at this conference, the model is used to design an optimized heater tube with improved temperature gradients. In the model presented here, the 2-D temperature distribution is simplified to separate the axial and radial temperature distributions within the heater tube and the surrounding insulation. Literature data for the temperature dependence of the electrical and thermal conductivities of the graphite tube were coupled to models for the thermal conductivity of the felt insulation, particularly including the effects of allowing for a gas mixture in the insulation. Experimental measurements of the temperature profile up to 1,500°C and radial heat fluxes up to 2,200°C were compared to the theoretical predictions of the model and good agreement was obtained.     

Enclosing all solutions of two-point boundary value problems for ODEs

The two-point boundary value problem (TPBVP) occurs in a wide variety of problems in engineering and science, including the modeling of chemical reactions, heat transfer, and diffusion, and the solution of optimal control problems. A TPBVP may have no solution, a single solution, or multiple solutions. A new strategy is presented for reliably locating all solutions of a TPBVP. The method determines narrow enclosures of all solutions that occur within a specified search interval. Key features of the method are the use of a new solver for parametric ODEs, which is used to produce guaranteed bounds on the solutions of nonlinear dynamic systems with interval-valued parameters and initial states, and the use of a constraint propagation strategy on the Taylor models used to represent the solutions of the dynamic system. Numerical experiments demonstrate the use and computational efficiency of the method.     

广州电视塔及广州电视台设计

信基建筑事务所(Information Based Architecture)是由Mark Hemel和Barbara Kuit于1998年在伦敦成立的,2002年办公地点迁往阿姆斯特丹.……     

Lateral hyperstriatal lesions disrupt simultaneous but not successive conditional discrimination learning of pigeons (Columba livia).

Explored, in 2 experiments, the effects of lateral vs medial laminar lesions of the hyperstriatum in pigeons; medial lesions were largely confined to the hyperstriatum accessorium, and lateral lesions to the hyperstriatum dorsale and hyperstriatum ventrale. In Exp 1, lateral, but not medial, lesions disrupted acquisition of a simultaneous conditional discrimination; both medial and lateral lesions disrupted reversal of the discrimination. The reversal deficits of the medial and lateral groups were quantitatively similar, and both groups showed exaggerated positional responding. In Exp 2, neither medial nor lateral lesions disrupted acquisition of a successive conditional discrimination. Lateral hyperstriatal damage does not obtain a general disruption of conditional learning; it is speculated that the lateral hyperstriatum may play a critical role in configural learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the lateral response of regular highrise frames

This paper introduces a simple approach for the study of the structural phenomena associated with the lateral response of regular highrise frames. The concept is based upon the assumption that the structure is composed of imaginary modules that fit within the actual bays of the framework, and that all imaginary modules deform through similar shapes by formation of points of inflexion at similar locations. The imaginary modules of a story are combined to form an equivalent ‘basic module’ that possesses the same structural characteristics as the corresponding story level subframe. The concept is used to establish an analogy between the lateral response of highrise structures and discretized Timoshenko beam-columns with similar boundary conditions. The properties of the basic module have been employed in conjunction with the techniques of finite difference calculus to derive the governing equation of motion of a regular discretized Timoshenko beam under uniform compression. The use of the concept is further utilized to obtain a number of closed form formulae for the initial design of multistory structures. These include expressions for the determination of the natural frequencies, the P-delta effects, as well as the critical buckling loads of regular multistory frames. Numerical examples have been provided to demonstrate the applications and the simplicity of the proposed solutions.     

Architecture for a Successful Computer-Integrated Manufacturing Program in a 4-year College or University

Computer-Integrated Manufacturing (CIM) has over the past decade become a key component in revitalizing U.S. manufacturing industry. To support much of this CIM activity, colleges and universities have started CIM-related courses and programs. A major problem that these schools have had is in determining the structure of their “CIM” program. This paper will discuss the major factors to be considered in developing the overall architecture for a CIM Program in a 4-year institution, detailing goals and objectives, participants and leadership roles, and the major components for a successful CIM Program. Curriculum issues are not discussed, as any specific curriculum will vary depending upon the degree program.     

On modeling the design of cellular manufacturing systems

A new optimization model is discussed for the design of cellular manufacturing systems. It is based on an integer programming formulation that updates some other models by eliminating redundant machine assignment and cost coefficients dependent on cell configuration. To reduce computational burdens, a simplified integer programming model and a decomposition algorithm are proposed. Several computer solutions were performed to evaluate the performance of the new model. The computational results are discussed.     

Effects of note-taking on perceived counselor social influence during a career counseling session.

Examined the effects of counselor note-taking behavior on participants' impressions of a counselor during a career counseling session. A total of 140 participants (70 men and 70 women) rated 1 of 2 videotapes designed to credibly simulate a real career counseling interview. Note-taking was the independent variable. Results of this study suggest that whether a counselor is observed in a note-taking or non-note-taking condition has no significant effect on perceived counselor expertness, attractiveness, or trustworthiness. However, there was a significantly greater willingness of the participants to see the counselor who refrained from note-taking. Results offer tentative suggestions for those counselors who choose to take notes during a career counseling session. (PsycINFO Database Record (c) 2010 APA, all rights reserved)