A frequency multiplier for reference frequency in frequency synthesizer systems

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.     

Designing control systems using exact and symbolic manipulations of formulae

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.     

Detecting variabilities of ECG signals by Lyapunov exponents

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%).     

Maximum volume cuboids for arbitrarily shaped in-situ rock blocks as determined by discontinuity analysis—A genetic algorithm approach

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).     

Statistics over features of ECG signals

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.     

Improvement of Field Water Distribution and Irrigation Techniques: The Southeastern Anatolia Project-GAP

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.     

Collision Free Motion Planning for Double Turret System Operating in a Common Workspace

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.

     

Fatigue crack closure and crack growth behaviour in a titanium alloy with different microstructures

Fatigue crack closure and crack growth behaviour in Ti–2.5 wt % Cu alloy with two equiaxed and two lamellar microstructures have been investigated by constant-load amplitudetests. Plasticity-induced crack closure and roughness-induced crack closure have been characterized separately by experimental methods. A change in closure mechanism from plasticity-induced crack closure at high K values (region of high stress intensity ranges)to roughness-induced crack closure at low K values occurs in a solution-annealed equiaxed microstructure, while plasticity-induced crack closure is the operative closure mechanism in an over-aged equiaxed microstructure over the whole range of K and roughness-induced crack closure occurs in two lamellar microstructures. The crack closing stress intensity factor for plasticity-induced crack closure increases continuously with increasing maximum stress intensity. The crack closing stress intensity factor for roughness-induced crack closure increases with increasing maximum stress intensity at low K, and remains constant at high K. Crack closure and crack path deflection have a significant influence on the crack growth rates. © 1998 Kluwer Academic Publishers     

考虑气储惯量互补的多能直流微网运行控制策略

多能互补直流微网对实现能源可持续发展具有重要意义。基于含风光气储等多种能源形式的典型直流微网,提出了考虑气储惯量互补的多能直流微网运行控制策略。针对微网内微型燃气轮机具有大惯量特性无法快速响应负荷变化的问题,提出一种微燃机与储能电池惯量互补的控制方法,利用储能电池动态响应快速的特点弥补微燃机动态特性的不足。所提控制策略可充分利用微燃机功率调节作用,降低系统成本,提高新能源利用率,对直流微网稳定运行提供保障。最后通过仿真验证所提控制策略的正确性与有效性。