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A constrained multivariable control strategy along with its application in more efficient thermal power plant control is presented in this paper. A neural network model-based nonlinear long-range predictive control algorithm is derived, which provides offset-free closed-loop behavior with a proper and consistent treatment of modeling errors and other disturbances. A multivariable controller is designed and implemented using this algorithm. The system constraints are taken into account by including them in the control algorithm using real-time optimization. By running a simulation of a 200 MW oil-fired drum-boiler thermal power plant over a load-profile along with suitable PRBS signals superimposed on controls, the operating data is generated. Neural network (NN) modeling techniques have been used for identifying global dynamic models (NNARX models) of the plant variables off-line from the data. To demonstrate the superiority of the strategy in a MIMO case, the controller has been used in the simulation to control main steam pressure and temperature, and reheat steam temperature during load-cycling and other severe plant operating conditions 相似文献
124.
Aluminium-lithium alloys hold promise of providing a breakthrough response to the crying need for lightweight alloys for use
as structurals in aerospace applications. Considerable worldwide research has gone into developing a range of these alloys
over the last three decades. As a result, substantial understanding has been developed of the microstructure-based micromechanisms
of strengthening, of fatigue and fracture as well as of anisotropy in mechanical properties. However, these alloys have not
yet greatly displaced the conventionally used denser Al alloys on account of their poorer ductility, fracture toughness and
low cycle fatigue resistance. This review aims to summarise the work pertaining to study of structure and mechanical properties
with a view to indicate the directions that have been and can be pursued to overcome property limitations. 相似文献
125.
126.
We present our results of Gamma Knife surgery for craniopharyngioma in nine patients. The current status of surgery, radiation therapy, intracavitary instillation of radionucleides and Gamma Knife surgery in the management of craniopharyngiomas is discussed. 相似文献
127.
A novel approach towards the realisation of future communication systems is presented, highlighting some key research-areas,
whose proper development will contribute to the development of the envisaged trends. The concept of a unified global infrastructure
is the core of this vision approach. Key-elements that need to be analysed are identified together with the approach required
for their effective investigation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
128.
Users' and applications' security requirements have been evaluated and described in this paper. Five issues of user and application security have been discussed. These issues deal with the aspects of ease-of-use, privacy, authentication, user rights and advertising. Then solutions have been proposed using existing protocols and a new concept of adaptive security is proposed and discussed for a foolproof security from user prospective. 相似文献
129.
Prasad R.Thakurdesai 《工具技术》2006,40(1)
巴尔查斯公司是世界一流的涂层供应商,作为UNAXIS集团中最具活力的一员,拥有世界领先的镀膜和真空技术.巴尔查斯长期致力于开发各种涂层及涂层工艺、销售系统以及生产设备,并且是唯一一家通过其目前设在欧洲、美洲和亚洲拥有70多个涂层中心的全球网络向世界各地的客户提供涂层服务的公司.巴尔查斯拥有世界领先的涂层设备,作为工具和精密元件耐磨涂层的供应者已经有27年之久.巴尔查斯的真空涂层系统广泛应用在提高各种工具和精密元件的性能上,效果十分显著.在金属切削、冲压成型和塑料模具等应用方面,巴尔查斯涂层在极大提高硬度的同时,能显著减少摩擦,提高生产能力,从而降低生产成本.实践证明,在使用巴尔查斯涂层后,汽车发动机、传动设备和水压系统精密部件的使用寿命被显著延长. 相似文献
130.
Stack filter design using selection probabilities 总被引:1,自引:0,他引:1
Selection probabilities, viz. rank and sample selection probabilities, quantify the impulse suppression, robustness, lowpass filtering ability, and detail preserving ability of stack filters. Closed-form expressions exist for computing selection probabilities from positive Boolean function describing the stack filter. We first present an analysis framework that interprets a Boolean vector to denote membership in a partition set. Using this framework a new algorithm to compute selection probabilities from positive Boolean functions is derived. Next a method to synthesize a stack filter from specified selection probabilities is presented. An underdetermined system of linear Diophantine equations is derived in the unknown elements of the C-matrix and the desired selection probabilities. This system of equations is solved to obtain the candidate solutions for the C-matrix. For each candidate C-matrix, an algorithm based on partition sets is used to derive one or more positive Boolean functions of the stack filter or show that none exists. 相似文献