Recent developments of stability control in mines, essentially based on Ge-doped Fibre Bragg Gratings(FBG) are reported including results about the different aspects of the system : accurate characterisations of FBG,s...
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ISBN:
(纸本)0819416991
Recent developments of stability control in mines, essentially based on Ge-doped Fibre Bragg Gratings
(FBG) are reported including results about the different aspects of the system : accurate characterisations of FBG,
sensor network topology and multiplexing method, user interface design and sensor packaging.
Nonlinear time step dynamic analyses have been performed on 24 rectangular single-storey steel framed buildings including a metal roof deck diaphragm and steel bracing bays along their exterior walls. The structures w...
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Nonlinear time step dynamic analyses have been performed on 24 rectangular single-storey steel framed buildings including a metal roof deck diaphragm and steel bracing bays along their exterior walls. The structures were designed according to current Canadian codes and were subjected to site specific ensembles of historical earthquake accelerograms. The analyses indicated that larger in-plane deformations and bending moments developed in the diaphragm compared to the values expected from the equivalent lateral force procedure commonly used in design. The distribution of the shear forces in the diaphragm was also found to deviate significantly from the linear distribution assumed in design. In addition, the ductility demand in the bracing bents exceeded the amount predicted by nonlinear analyses performed on equivalent single-degree of freedom systems. Based on these results, preliminary design guidelines have been proposed for predicting the deformations, moments and shear forces in roof diaphragm as well as for confining inelastic action in the vertical bracing elements.
The advantages of optical coatings realized by Sputtering versus thermal evaporation by crucible or Electron Gun, are very well known, but this technique is used only partially for dielectric coatings despite of a wid...
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ISBN:
(纸本)0819415863
The advantages of optical coatings realized by Sputtering versus thermal evaporation by crucible or Electron Gun, are very well known, but this technique is used only partially for dielectric coatings despite of a wide use in semiconductors and microcircuits, due to the slowness of RF Sputtering processes when starting from dielectric targets. This paper describes a DC Reactive Magnetron Sputtering technique from metal target set up at ***.v. for deposition of multilayer coatings, with cycle times comparable-or even faster-than conventional solution. The advantages of this process consist in obtaining films with high optical and mechanical performances with high repeatability on room temperature substrates. Pumping cycle can thus be faster and dead time for substrates heating and cooling down can be avoided, characteristics which plastic substrates can particularly take advantage of. Performances of the realized coatings on glass and plastic substrates, together with cycle time and material costs, are finally compared to results obtainable by Electron Beam Gun Reactive Deposition.
Calculation characteristics and electrode configurations of Magnetron-Injection Guns (MIG) operating in Space-Charge Limited current (SCLC) regime for various frequency ranges are given. The design pequliarities and e...
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We have outlined our approach for developing an integrated system for controlling centerline bead temperature in arc welding. An optical thermography system, based on an inexpensive and readily available video camera,...
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We have outlined our approach for developing an integrated system for controlling centerline bead temperature in arc welding. An optical thermography system, based on an inexpensive and readily available video camera, was presented. Temperature measurements obtained with this system are within 10% of those measured by a calibrated two-color optical pyrometer. A low-order model describing the centerline temperature dynamics was developed. Two strategies for tuning a simple PI temperature controller were given. We first used off-line sensitivity-based tuning to optimize the controller gains. This method is adequate for systems whose dynamics are time invariant. For GMAW, however, the plant parameters can vary widely due to changes in plate thickness as well as other operating parameters. For this reason we applied a sensitivity-based pseudogradient adaptive algorithm for self-tuning the PI controller. The self-tuning controller is robust to changes in the operating conditions and is therefore more useful than a PI controller with fixed gains. It is also insensitive to the noise present in the GMAW system. The control design presented in this paper makes no attempt to counter the delay between the arc current command and centerline temperature output. Instead, the sample time was deliberately increased so that this delay could be ignored. To increase the bandwidth of the closed-loop system it is necessary to incorporate a Smith predictor or similar mechanism to increase the response time of the closed-loop system. We are currently investigating the design of a predictive controller.< >
We report on the use of HF chemical sensors to improve the control of both 100:1 and 15:1 HF etch baths used in a bipolar technology manufacturing line. The commercial HF sensor selected for this application is based ...
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ISBN:
(纸本)081941669X;9780819416698
We report on the use of HF chemical sensors to improve the control of both 100:1 and 15:1 HF etch baths used in a bipolar technology manufacturing line. The commercial HF sensor selected for this application is based on the induction of a current from a primary coil to a secondary coil when the coils are immersed in hydrofluoric acid-water solutions. The design of the sensor is such that only polymer surfaces are exposed to the acid. The output of the sensors are used in a Wet Chemical Advisor we have developed to improve the operator control of the etch baths. We present data demonstrating how the Advisor was used to understand the sources of both episodic and drift variations to the specified bath chemistries. The use of the Wet Chemical Advisor platform has eliminated the need for process monitor wafers, and has greatly reduced the time required by operators for making up or maintaining the facilities within specifications. Historical information is stored in the PC for back reference and for quality control documentation.
As design rules shrink to meet the needs of advanced chips, the allocation of allowable errors between sources gets ever more critical. This paper will examine the error sources and budgets for current technologies an...
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This paper introduces the Grumman Autonomous Long Life vehicle (LLv) research platform currently under development within Grumman's Corporate Research Center. Topics to be discussed include the system architecture...
ISBN:
(纸本)0819413232
This paper introduces the Grumman Autonomous Long Life vehicle (LLv) research platform currently under development within Grumman's Corporate Research Center. Topics to be discussed include the system architecture, mechanical design, the actuators, the sensor subsystems, the computing and control hardware, the software system, and safety issues. current progress and plans for the project also are described.
A general architecture for neuro-genetw adaptive control is described and contrasted with purely neural approaches to adaptive control. The system is demonstrated on the attitude controiproblem for a rigid body (satel...
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The design of control algorithms for large space structures, possessing nonlinear dynamics which are often time-varying and likely ill-modeled, presents great challenges for all current methodologies. These limitation...
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ISBN:
(纸本)0819415472
The design of control algorithms for large space structures, possessing nonlinear dynamics which are often time-varying and likely ill-modeled, presents great challenges for all current methodologies. These limitations have led to the pursuit of a robust and fault tolerant structural controller. In the present paper, we propose the use of adaptive time-delay radial basis function (ATDRBF) networks as a learning controller in system identification and dynamic control of flexible structures. The ability of such neural networks to approximate arbitrary continuous functions offers an efficient means of vibration suppression and trajectory maneuvering for precision pointing capability. The ATDRBF network, which incorporates adaptive time-delays and interconnection weights, provides a feasible and flexible modeling technique to effectively capture all of the spatiotemporal interactions among the structure members. In the spirit of model reference adaptive control, we utilize the ATDRBF network as a building block to allow the neural network to function as a closed-loop controller. The controller regulate the dynamics of the nonlinear plant to follow a prespecified reference model asymptotically. This paper addresses the theoretical foundation of the architecture and demonstrates its applicability via specific examples.
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