194 research outputs found
Optimal Meter Placement by Reconciliation Conventional Measurements and Phasor Measurement Units (PMUs)
The success of state estimation depends on the number, type and location of the established meters and RTUs on the system. A new method by incorporating conventional measurements and New Technology of Phasor Measurement Units (PMU) is proposed. Conventional meters (power injection and power flow measurements) are allocated in order to reduce the number of meters, RTUs, critical measurements, critical sets and leverage points, and also to improve the numerical stability of equations; a genetic algorithm is used for optimization. A second step involves adding PMUs in areas in which it is expected that the accuracy of state estimation will be improved
Comparative Studies of Different Control Strategies of a Dynamic Voltage Restorer Based on Matrix Converter
A dynamic voltage restorer (DVR) with no energy storage is studied. By using a matrix converter instead of the conventional AC/DC/AC converters, elimination of the DC-link capacitor is possible. The switching algorithm of matrix converter is the space vector modulation. There are different compensation algorithms to control the conventional DVR. These methods have been analyzed in this paper for the proposed matrix-converter-based DVR. A deep analysis through different diagrams would show the advantages or disadvantages of each compensation method. Equations for all methods are derived, and the characteristics of algorithms are compared with each other
Relationship between bridging and dimensions of sella turcica with classification of craniofacial skeleton
Purpose: In orthodontics, it is essential to determine the craniofacial skeleton pattern (class I, II, III) for planning treatment. Sella turcica bridging that is seen on lateral cephalometric radiographs is considered as a normal finding. This study aimed to compare sella turcica bridging and its dimensions in patients with various craniofacial patterns. Material and methods: A total of 105 lateral cephalometric radiographs (53 men and 52 women), aged 14-26 years, were randomly and equally assigned to three groups of class I, II, and III, respectively. The length, diameter, and depth of the sella turcica as well as sella turcica bridging were determined on radiographs. The chi-squared test was used for assessing the relationship between sella turcica bridging and craniofacial skeleton classification. ANOVA was used for assessing the relationship between the dimensions of the sella turcica and craniofacial skeleton classification. The Pearson's correlation coefficient was used for assessing the relationship between age and the dimensions of the sella turcica. Results: The sella turcica had a normal shape in 64.76% of patients, whereas 35.33% of patients had sella turcica bridging. In total, 11.42% of patients belonged to class I, 34.28% to class II, and 66.62% to class III. The diameter of the sella turcica had a significant relationship with age; the diameter of the sella turcica increased with age (p < 0.001). Conclusions: There is a significant relationship between craniofacial skeleton patterns and sella turcica bridging, i.e., the incidence of sella turcica bridging is higher in class III patients. The sella turcica had a greater diameter in older patients
Comparison of VSC and Z-source converter: power system application approach
Application of equipment with power electronic converter interface such as distributed generation, FACTS and HVDC, is growing up intensively. On the other hand, various types of topologies have been proposed and each of them has some advantages. Therefore, appropriateness of each converter regarding to the application is a main question for designers and engineers. In this paper, a part of this challenge is responded by comparing a typical Voltage-Source Converter (VSC) and Z-Source Converter (ZSC), through high power electronic-based equipment used in power systems. Dynamic response, stability margin, Total Harmonic Distortion (THD) of grid current and fault tolerant are considered as assessment criteria. In order to meet this evaluation, dynamic models of two converters are presented, a proper control system is designed, a small signal stability method is applied and responses of converters to small and large perturbations are obtained and analysed by PSCAD/EMTDC
Triangular and trapezoidal fuzzy state estimation with uncertainty on measurements
In this paper, a new method for uncertainty analysis in fuzzy state estimation is proposed. The uncertainty is expressed in measurements. Uncertainties in measurements are modelled with different fuzzy membership functions (triangular and trapezoidal). To find the fuzzy distribution of any state variable, the problem is formulated as a constrained linear programming (LP) optimization. The viability of the proposed method would be verified with the ones obtained from the weighted least squares (WLS) and the fuzzy state estimation (FSE) in the 6-bus system and in the IEEE-14 and 30 bus system
Expressive Animated Character Sequences Using Knowledge-Based Painterly Rendering
We propose a technique to enhance emotionalexpressiveness in games and animations. Artists have usedcolors and painting techniques to convey emotions in theirpaintings for many years. Moreover, researchers have foundthat colors and line properties affect users\u27 emotions. Wepropose using painterly rendering for character sequencesin games and animations with a knowledge-based approach. This technique is especially useful for parametric facial sequences. We introduce two parametric authoring tools foranimation and painterly rendering and a method to integrate them into a knowledge-based painterly rendering system. Furthermore, we present the results of a preliminarystudy on using this technique for facial expressions in stillimages. The results of the study show the effect of different color palettes on the intensity perceived for an emotionby users. The proposed technique can provide the animatorwith a depiction tool to enhance the emotional content of acharacter sequence in games and animations
Mimicking Classical Noise in Ion Channels by Quantum Decoherence
The mechanism of selectivity in ion channels is still an open question in
biology. According to recent proposals, it seems that the selectivity filter of
the ion channel, which plays a key role in the channel's function, may show
quantum coherence, which can play a role in explaining the selection mechanism
and conduction of ions. However, due to decoherence theory, the presence of
environmental noise causes decoherence and loss of quantum effects. Sometimes
we hope that the effect of calssical noise of the environment in ion channels
can be modeled through a picture whose the quantum decoherence theory presents.
In this paper, we simulated the behavior of the ion channel system in the
Spin-Boson model using the unitary evolution of a stochastic Hamiltonian
operator under the classical noise model. Also, in a different approach, we
modeled the system evolution as a two-level Spin-Boson model with tunneling
interacting with a bath of harmonic oscillators, using decoherence theory. The
results of this system were discussed in different classical and quantum
regimes. By examining the results it was found that the Spin-Boson model at a
high hopping rate of Potassium ions can simulate the behavior of the system in
the classical noise approach. This result is another proof for the fact that
ion channels need high speed for high selectivity
Comparison between different control strategies of a Z-source inverter based dynamic voltage restorer
In this paper, dynamic voltage restorer (DVR) compensation methods are compared to each other for the load side connected shunt converter topology of z-source inverter based DVR to choose the best method. Four different topologies are recognized for DVR that two of them have energy storage devices, and two topologies have no energy storage that take ener\-gy from the grid during the period of compensation. Here the load side connected shunt converter topology that takes necessary energy from the grid is used. Pre-sag compensation, in-phase compensation, energy-optimized methods are the three DVR compensation methods that studied and compared. A deep analysis through different diagrams would show the advantages or disadvantages of each compensation method. Equations for all methods are derived and the characteristics of algorithms are compared with each other. The simulation results done by SIMULINK/ MATLAB shows compensating by this topology based on the compensation methods
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