A low jitter frequency multiplier, which requires less power, area, and design complexity than reference multiplying PLL or DLL circuits can be used to generate the reference frequency for a low phase noise frequency synthesizer. This paper proposes a mixed signal solution based on the fact that the average DC value of a signal is proportional to its duty cycle. The solution uses a feedback loop with coarse and fine delay resolution to generate a \(90^{\circ }\) phase shifted clock that is used to produce a doubled frequency signal with 50% duty cycle. This method can be used to multiply the input frequency of 40 MHz by multiples of 2, up to 16. The design is implemented in 65 nm UMC CMOS process. Operating from 1.2-V supply, it dissipates 0.46 to 1.2 mA at output frequencies 80–640 MHz, achieving ? 162.3 and ? 139 dBc/Hz phase noise at 1 MHz offset, respectively. 相似文献
The potential of symbolic algebra for the design of control systems is illustrated through several examples. It has been shown in particular, that (a) the exact calculations provided by symbolic algebra can be used to utilize some of the direct (but numerically error prone) methods efficiently in control system design, and (b) symbolic manipulations by a computer can help control engineers at several stages of the design. The block diagram reduction, calculation of all stabilizing controllers, dominant pole assignment and robust pole assignment are taken as case studies. 相似文献
An approach based on the consideration that electrocardiogram (ECG) signals are chaotic signals was presented for automated
diagnosis of electrocardiographic changes. This consideration was tested successfully using the nonlinear dynamics tools,
like the computation of Lyapunov exponents. Multilayer perceptron neural network (MLPNN) architectures were formulated and
used as basis for detection of variabilities of ECG signals. Four types of ECG beats (normal beat, congestive heart failure
beat, ventricular tachyarrhythmia beat, atrial fibrillation beat) obtained from the Physiobank database were classified. The
computed Lyapunov exponents of the ECG signals were used as inputs of the MLPNNs trained with backpropagation, delta-bar-delta,
extended delta-bar-delta, quick propagation, and Levenberg–Marquardt algorithms. The performances of the MLPNN classifiers
were evaluated in terms of classification accuracies. The results confirmed that the MLPNN trained with the Levenberg–Marquardt
algorithm has potential in detecting the variabilities of the ECG signals (total classification accuracy was 95.00%). 相似文献
The block stone industry is one of the main commercial use of rock. The economic potential of any block quarry depends on the recovery rate, which is defined as the total volume of useful rough blocks extractable from a fixed rock volume in relation to the total volume of moved material. The natural fracture system, the rock type(s) and the extraction method used directly influence the recovery rate. The major aims of this study are to establish a theoretical framework for optimising the extraction process in marble quarries for a given fracture system, and for predicting the recovery rate of the excavated blocks. We have developed a new approach by taking into consideration only the fracture structure for maximum block recovery in block quarries. The complete model uses a linear approach based on basic geometric features of discontinuities for 3D models, a tree structure (TS) for individual investigation and finally a genetic algorithm (GA) for the obtained cuboid volume(s). We tested our new model in a selected marble quarry in the town of ?scehisar (AFYONKARAH?SAR—TURKEY). 相似文献
This paper presented the usage of statistics over the set of the features representing the electrocardiogram (ECG) signals. Since classification is more accurate when the pattern is simplified through representation by important features, feature extraction and selection play an important role in classifying systems such as neural networks. Multilayer perceptron neural network (MLPNN) architectures were formulated and used as basis for detection of variabilities of the ECG signals. Four types of ECG beats (normal beat, congestive heart failure beat, ventricular tachyarrhythmia beat, atrial fibrillation beat) obtained from the Physiobank database were classified. The selected Lyapunov exponents, wavelet coefficients and the power levels of power spectral density (PSD) values obtained by eigenvector methods of the ECG signals were used as inputs of the MLPNN trained with Levenberg–Marquardt algorithm. The classification results confirmed that the proposed MLPNN has potential in detecting the variabilities of the ECG signals. 相似文献
ABSTRACT The Southeastern Anatolia Project-GAP is an integrated regional development project implemented in southeast Turkey. The project cows all development-related sectors such as agriculture, industry, health care, education. tourism, transportation, and telecommunications. Water resources development is one most important component of the project. Rational use of water is the goal in every aspect of development, be it hydropower, irrigation, or flood control. To complement the efforts to optimize water use in irrigated agriculture, a project has been carried out in regard to on-farm equipment and management of water. This paper describes several equipment and management combinations, applied to a very large irrigation area. ranging from gravity to sprinkler irrigation, and from upstream to downstream control of water. Five different applications are analyzed in this study along with their technical, economic, and operational merits and disadvantages. The project area is selected in the Sanliurfa-Harran Plains, the largest one-piece scheme to be opened to irrigation in GAP It is owned and cultivated by private farmers, and as such, it is expected to act as a large-scale, real-world laboratory to test different irrigation practices in actual conditions. 相似文献
Instead of using the tedious process of turret teaching, an off-line path planning algorithm has been developed for military turrets to improve their accuracy and efficiency. In the scope of this research, an algorithm is proposed to search a path in three different types of configuration spaces which are rectangular, circular and torus shaped by providing three converging options named as fast, medium and optimum depending on the application. With the help of the proposed algorithm, 4-dimensional (D) path planning problem was realized as 2-D + 2-D by using 6 sequences and their options. In order to find a heuristic path on these 2-D configuration maps, the A* algorithm is implemented, which is usually used to find a heuristic path on Cartesian Workspace. Firstly, 4-D configuration space of the double-turret system is obtained by using the method of intersection of point clouds where the bodies in the system are meshed and converted into points. With the help of random simulations, the sequences and the options of these sequences are provided in an appropriate order. A sample path planning was made to examine the performance of the algorithm and thus the converging options. The results obtained for 3 different converging options were simulated on the model of the double-turret system and it was observed that there was no collision between any bodies in these three options. Hence, a collision free motion planning can be carried out for double-turret system operating in a common workspace.