Linear,parameter-varying control of a supercavitating vehicle

A systematic approach to parameter-dependent control synthesis of a high-speed supercavitation vehicle (HSSV) is presented. The aim of the control design is to provide robust reference tracking across a large flight envelope, while directly accounting for the interaction of liquid and gas phases with the vehicle. A nonlinear dynamic HSSV model is presented and discussed relative to the actual vehicle. A linear, parameter-varying (LPV) controller is synthesized for angle rate tracking in the presence of model uncertainty. The control design takes advantage of coupling in the governing equations to achieve improved performance. Multiple LPV controllers synthesized for smaller overlapping regions of the parameter space are blended together, providing a single controller for the full flight envelope. Time-domain simulations implemented on high-fidelity simulations, provide insight into the performance and robustness of the proposed scheme.     

Evaluation of six night vision enhancement systems: qualitative and quantitative support for intelligent image processing

OBJECTIVE: An evaluation study was conducted to answer the question of which system properties of night vision enhancement systems (NVESs) provide a benefit for drivers without increasing their workload. BACKGROUND: Different infrared sensor, image processing, and display technologies can be integrated into an NVES to support nighttime driving. Because each of these components has its specific strengths and weaknesses, careful testing is required to determine their best combination. METHOD: Six prototypical systems were assessed in two steps. First, a heuristic evaluation with experts from ergonomics, perception, and traffic psychology was conducted. It produced a broad overview of possible effects of system properties on driving. Based on these results, an experimental field study with 15 experienced drivers was performed. Criteria used to evaluate the development potential of the six prototypes were the usability dimensions of effectiveness, efficiency, and user satisfaction (International Organization for Standardization, 1998). RESULTS: Results showed that the intelligibility of information, the easiness with which obstacles could be located in the environment, and the position of the display presenting the output of the system were of crucial importance for the usability of the NVES and its acceptance. Conclusion: All relevant requirements are met best by NVESs that are positioned at an unobtrusive location and are equipped with functions for the automatic identification of objects and for event-based warnings. APPLICATION: These design recommendations and the presented approach to evaluate the systems can be directly incorporated into the development process of future NVESs.     

On Interval Systems [<Emphasis Type="Italic">x</Emphasis>] = [<Emphasis Type="Italic">A</Emphasis>][<Emphasis Type="Italic">x</Emphasis>] + [<Emphasis Type="Italic">b</Emphasis>] and the Powers of Interval Matrices in Complex Interval Arithmetics

For the interval system of equations defined by [x] = [A][x] + [b] we derive necessary and sufficient criteria for the existence of solutions [x]. Furthermore we give necessary and sufficient criteria for the convergence of powers of [A]. In contrast to former results we treat complex interval arithmetics.     

Satisfying customer preferences via mass customization and mass production

Two operational formats namely mass customization and mass production can be implemented to satisfy customer preference-based demand. The mass customization system consists of two stages: the initial build-to-stock phase and the final customize-to-order phase. The mass production system has a single stage: building products with pre-determined specifications to stock. In each case, the company makes decisions on the number of initial product variants, product specifications, production quantities and product pricing. Under a uniform customer preference distribution, the optimal number of base-product variants resembles the well known economic order quantity solution, and the optimal product specifications are equally spaced. We characterize three possible benefits of mass customization: (i) the gained surplus from offering each customer her ideal product; (ii) extra revenue from price discrimination; and (iii) reduced costs due to risk pooling under stochastic demand.     

Electronically controllable microvalves based on smart hydrogels: magnitudes and potential applications

Electronically controllable microvalves based on temperature sensitive hydrogels as actuators are described. A thermal-electronic interface was used for electronic control of the liquid flow. The hydrogel actuators were directly placed in a flow channel. They used the process medium as the swelling agent. Because of the direct placement into the channel the elastic properties of the hydrogel actuator were utilized to improve the pressure insensitivity, to achieve high particle tolerance and to avoid a leakage flow. The microvalves show an extremely simple structure. They can be fabricated using conventional micro technology within a few technical steps. The microvalves can also be miniaturized to a currently unrivalled extent of about 4 /spl mu/m/spl times/4 /spl mu/m/spl times/1/spl mu/m. Valves for "laboratory on chip" applications can already be obtained. The switching times of the electronically controllable microvalves based on hydrogels are 0.3 s to 10 s.     

A data acquisition and image processing system for scanning tunneling microscopy

We have built a dedicated data acquisition and image processing system for scanning tunneling microscopy (STM). Data acquisition is accomplished by a fast 8-bit add-on frame grabber which may be synchronized either to standard TV frequencies or to asynchronous slow scan data sources such as STM or SEM. A 32-bit minicomputer is used for image processing by means of a comprehensive interactive-language which also allows the data acquisition process to be controlled. To speed up time-consuming computations, a floating-point array processor was linked to the system.     

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