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1.
Gerhard Jäger 《Journal of Logic, Language and Information》2002,11(4):427-451
In this paper, we discuss some formal properties of the model ofbidirectional Optimality Theory that was developed inBlutner (2000). We investigate the conditions under whichbidirectional optimization is a well-defined notion, and we give aconceptually simpler reformulation of Blutner's definition. In thesecond part of the paper, we show that bidirectional optimization can bemodeled by means of finite state techniques. There we rely heavily onthe related work of Frank and Satta (1998) about unidirectionaloptimization. 相似文献
2.
数字微流体的产生是压电材料为基片的微流控芯片进行微流分析的前提,报道了在压电基片上应用声表面波技术产生数字微流体的方法.在128°旋转Y切割X传播方向的LiNbO3基片上集成PDMS微通道,在微通道出口一侧为经疏水处理的铝薄片,注射泵产生恒定流量的微流体经PDMS微通道到达铝薄片并聚集,当聚集的微流体体积足够大时,微流体克服表面张力作用下滑到达压电基片,并在中心频率为27.7 MHz叉指换能器激发的声表面波作用下输运,实现微流体的数字化.同时,理论分析了微流体在铝薄片表面上受力状况,并以水为实验对象,进行微流体数字化实验.结果表明,声表面波作用下能精确产生微升量级数字微流体,为压电微流控芯片提供了一种新的微流体引入方法. 相似文献
3.
Formal translations constitute a suitable framework for dealing with many problems in pattern recognition and computational linguistics. The application of formal transducers to these areas requires a stochastic extension for dealing with noisy, distorted patterns with high variability. In this paper, some estimation criteria are proposed and developed for the parameter estimation of regular syntax-directed translation schemata. These criteria are: maximum likelihood estimation, minimum conditional entropy estimation and conditional maximum likelihood estimation. The last two criteria were proposed in order to deal with situations when training data is sparse. These criteria take into account the possibility of ambiguity in the translations: i.e., there can be different output strings for a single input string. In this case, the final goal of the stochastic framework is to find the highest probability translation of a given input string. These criteria were tested on a translation task which has a high degree of ambiguity. 相似文献
4.
5.
Smart Electroceramics 总被引:8,自引:0,他引:8
"Smart" materials have the ability to perform both sensing and actuating functions. Passively smart materials respond to external change in a useful manner without assistance, whereas actively smart materials have a feedback loop which allows them to both recognize the change and initiate an appropriate response through an actuator circuit. Many smart materials are analogous to biological systems: piezoelectric hydrophones are similar in mechanism to the "ears" by which a fish senses vibrations. Piezoelectrics with electromechanical coupling, shape-memory materials that can "remember" their original shape, electrorheological fluids with adjustable viscosities, and chemical sensors which act as synthetic equivalents to the human nose are examples of smart electroceramics. "Very smart" materials, in addition to sensing and actuating, have the ability to "learn" by altering their property coefficients in response to the environment. Integration of these different technologies into compact, multifunction packages is the ultimate goal of research in the area of smart materials. 相似文献
6.
Ch. M. Gadzhiev 《Measurement Techniques》2006,49(4):357-366
A recurrent algorithm is derived for estimating the parameters of a calibration curve with allowance for the errors in reproducing
the inputs. That algorithm is combined with a proposed rule for halting the calibration to reduce considerably the length
of the calibration, which promises a real economic advantage.
__________
Translated from Izmeritel’naya Tekhnika, No. 4, pp. 32–38, April, 2006. 相似文献
7.
Capacitive micromachined ultrasonic transducers (CMUTs) bring the fabrication technology of standard integrated circuits into the field of ultrasound medical imaging. This unique property, combined with the inherent advantages of CMUTs in terms of increased bandwidth and suitability for new imaging modalities and high frequency applications, have indicated these devices as new generation arrays for acoustic imaging. The advances in microfabrication have made possible to fabricate, in few years, silicon-based electrostatic transducers competing in performance with the piezoelectric transducers. This paper summarizes the fabrication, design, modeling, and characterization of 1D CMUT linear arrays for medical imaging, established in our laboratories during the past 3 years. Although the viability of our CMUT technology for applications in diagnostic echographic imaging is demonstrated, the whole process from silicon die to final probe is not fully mature yet for successful practical applications. 相似文献
8.
文中介绍一套可拆式传感器系统设计与制作,利用超声导波原理对水下管道的腐蚀进行检测,基于厚度剪切模式的压电陶瓷和可拆式固定装置组成,可拆式传感器系统包括传感器PZT特别设计,并且可以把传感器装置夹在要检测的管道上。当对水下设备的管道进行了一系列的测试,结果表明传感器系统能够有效地激发和接收T(0,1)模式的超声导波,由于T(0,1)模式超声导波能够在水下管道上长距离传播,因此适用于缺陷检测。人为缺口的回波信号与缺口的尺寸以及位置具有良好的相关性。研究表明这一可拆式传感器系统能够利用导波有效地对水下管道进行检测。 相似文献
9.
章安良 《固体电子学研究与进展》2007,27(2):280-284
提出了采用PSPICE仿真声表面波器件的方法,它将叉指换能器一个周期段Mason等效电路复阻抗采用LC串并联网络等效,并以子电路形式由叉指换能器等效电路调用,两换能器间声传播路径采用等延迟时间的无损耗传输线等效,同时考虑外电路影响,仿真得到的异型声表面波器件的幅度特性与实测结果基本相符。 相似文献
10.
介绍振弦式传感器的数学模型及工作原理,给出了该传感器信号采集卡的设计方案。分析了激振与拾振电路的设计,传感器信号频率的等精度测量电路设计,以及采用CAN总线实现与主控卡相互通信的智能节点设计。该采集卡作为一个嵌入式智能单元,可实现根据不同应用需要与其他传感器采集卡自由组合,构成一个灵活的集成数据采集系统硬件平台。 相似文献