Balsalobre-Fernández, Carlos; Tejero-González, Carlos M; Del Campo-Vecino, Juan; Alonso-Curiel, Dionisio
2013-03-01
The aim of this study was to determine the effects of a power training cycle on maximum strength, maximum power, vertical jump height and acceleration in seven high-level 400-meter hurdlers subjected to a specific training program twice a week for 10 weeks. Each training session consisted of five sets of eight jump-squats with the load at which each athlete produced his maximum power. The repetition maximum in the half squat position (RM), maximum power in the jump-squat (W), a squat jump (SJ), countermovement jump (CSJ), and a 30-meter sprint from a standing position were measured before and after the training program using an accelerometer, an infra-red platform and photo-cells. The results indicated the following statistically significant improvements: a 7.9% increase in RM (Z=-2.03, p=0.021, δc=0.39), a 2.3% improvement in SJ (Z=-1.69, p=0.045, δc=0.29), a 1.43% decrease in the 30-meter sprint (Z=-1.70, p=0.044, δc=0.12), and, where maximum power was produced, a change in the RM percentage from 56 to 62% (Z=-1.75, p=0.039, δc=0.54). As such, it can be concluded that strength training with a maximum power load is an effective means of increasing strength and acceleration in high-level hurdlers.
Solar Panel Maximum Power Point Tracker for Power Utilities
Sandeep Banik,
2014-01-01
Full Text Available ―Solar Panel Maximum Power Point Tracker For power utilities‖ As the name implied, it is a photovoltaic system that uses the photovoltaic array as a source of electrical power supply and since every photovoltaic (PV array has an optimum operating point, called the maximum power point, which varies depending on the insolation level and array voltage. A maximum power point tracker (MPPT is needed to operate the PV array at its maximum power point. The objective of this thesis project is to build a photovoltaic (PV array Of 121.6V DC Voltage(6 cell each 20V, 100watt And convert the DC voltage to Single phase 120v,50Hz AC voltage by switch mode power converter‘s and inverter‘s.
Maximum power point tracking for photovoltaic applications by using two-level DC/DC boost converter
Moamaei, Parvin
Recently, photovoltaic (PV) generation is becoming increasingly popular in industrial applications. As a renewable and alternative source of energy they feature superior characteristics such as being clean and silent along with less maintenance problems compared to other sources of the energy. In PV generation, employing a Maximum Power Point Tracking (MPPT) method is essential to obtain the maximum available solar energy. Among several proposed MPPT techniques, the Perturbation and Observation (P&O;) and Model Predictive Control (MPC) methods are adopted in this work. The components of the MPPT control system which are P&O; and MPC algorithms, PV module and high gain DC-DC boost converter are simulated in MATLAB Simulink. They are evaluated theoretically under rapidly and slowly changing of solar irradiation and temperature and their performance is shown by the simulation results, finally a comprehensive comparison is presented.
Maximum Power from a Solar Panel
Michael Miller
2010-01-01
Full Text Available Solar energy has become a promising alternative to conventional fossil fuel sources. Solar panels are used to collect solar radiation and convert it into electricity. One of the techniques used to maximize the effectiveness of this energy alternative is to maximize the power output of the solar collector. In this project the maximum power is calculated by determining the voltage and the current of maximum power. These quantities are determined by finding the maximum value for the equation for power using differentiation. After the maximum values are found for each time of day, each individual quantity, voltage of maximum power, current of maximum power, and maximum power is plotted as a function of the time of day.
Analysis of Photovoltaic Maximum Power Point Trackers
Veerachary, Mummadi
The photovoltaic generator exhibits a non-linear i-v characteristic and its maximum power point (MPP) varies with solar insolation. An intermediate switch-mode dc-dc converter is required to extract maximum power from the photovoltaic array. In this paper buck, boost and buck-boost topologies are considered and a detailed mathematical analysis, both for continuous and discontinuous inductor current operation, is given for MPP operation. The conditions on the connected load values and duty ratio are derived for achieving the satisfactory maximum power point operation. Further, it is shown that certain load values, falling out of the optimal range, will drive the operating point away from the true maximum power point. Detailed comparison of various topologies for MPPT is given. Selection of the converter topology for a given loading is discussed. Detailed discussion on circuit-oriented model development is given and then MPPT effectiveness of various converter systems is verified through simulations. Proposed theory and analysis is validated through experimental investigations.
Zipf's law, power laws and maximum entropy
Visser, Matt
2013-04-01
Zipf's law, and power laws in general, have attracted and continue to attract considerable attention in a wide variety of disciplines—from astronomy to demographics to software structure to economics to linguistics to zoology, and even warfare. A recent model of random group formation (RGF) attempts a general explanation of such phenomena based on Jaynes' notion of maximum entropy applied to a particular choice of cost function. In the present paper I argue that the specific cost function used in the RGF model is in fact unnecessarily complicated, and that power laws can be obtained in a much simpler way by applying maximum entropy ideas directly to the Shannon entropy subject only to a single constraint: that the average of the logarithm of the observable quantity is specified.
Zipf's law, power laws, and maximum entropy
Visser, Matt
2012-01-01
Zipf's law, and power laws in general, have attracted and continue to attract considerable attention in a wide variety of disciplines - from astronomy to demographics to economics to linguistics to zoology, and even warfare. A recent model of random group formation [RGF] attempts a general explanation of such phenomena based on Jaynes' notion of maximum entropy applied to a particular choice of cost function. In the present article I argue that the cost function used in the RGF model is in fact unnecessarily complicated, and that power laws can be obtained in a much simpler way by applying maximum entropy ideas directly to the Shannon entropy subject only to a single constraint: that the average of the logarithm of the observable quantity is specified.
Maximum Safety Regenerative Power Tracking for DC Traction Power Systems
Guifu Du
2017-02-01
Full Text Available Direct current (DC traction power systems are widely used in metro transport systems, with running rails usually being used as return conductors. When traction current flows through the running rails, a potential voltage known as “rail potential” is generated between the rails and ground. Currently, abnormal rises of rail potential exist in many railway lines during the operation of railway systems. Excessively high rail potentials pose a threat to human life and to devices connected to the rails. In this paper, the effect of regenerative power distribution on rail potential is analyzed. Maximum safety regenerative power tracking is proposed for the control of maximum absolute rail potential and energy consumption during the operation of DC traction power systems. The dwell time of multiple trains at each station and the trigger voltage of the regenerative energy absorbing device (READ are optimized based on an improved particle swarm optimization (PSO algorithm to manage the distribution of regenerative power. In this way, the maximum absolute rail potential and energy consumption of DC traction power systems can be reduced. The operation data of Guangzhou Metro Line 2 are used in the simulations, and the results show that the scheme can reduce the maximum absolute rail potential and energy consumption effectively and guarantee the safety in energy saving of DC traction power systems.
Maximum power operation of interacting molecular motors
Golubeva, Natalia; Imparato, Alberto
2013-01-01
We study the mechanical and thermodynamic properties of different traffic models for kinesin which are relevant in biological and experimental contexts. We find that motor-motor interactions play a fundamental role by enhancing the thermodynamic efficiency at maximum power of the motors......, as compared to the non-interacting system, in a wide range of biologically compatible scenarios. We furthermore consider the case where the motor-motor interaction directly affects the internal chemical cycle and investigate the effect on the system dynamics and thermodynamics....
Werner, Stefanie [Umweltbundesamt, Dessau-Rosslau (Germany). Fachgebiet II 2.3
2011-05-15
When offshore wind farms are constructed, every single pile is hammered into the sediment by a hydraulic hammer. Noise levels at Horns Reef wind farm were in the range of 235 dB. The noise may cause damage to the auditory system of marine mammals. The Federal Environmental Office therefore recommends the definition of maximum permissible noise levels. Further, care should be taken that no marine mammals are found in the immediate vicinity of the construction site. (AKB)
Individual Module Maximum Power Point Tracking for Thermoelectric Generator Systems
Vadstrup, Casper; Schaltz, Erik; Chen, Min
2013-07-01
In a thermoelectric generator (TEG) system the DC/DC converter is under the control of a maximum power point tracker which ensures that the TEG system outputs the maximum possible power to the load. However, if the conditions, e.g., temperature, health, etc., of the TEG modules are different, each TEG module will not produce its maximum power. If each TEG module is controlled individually, each TEG module can be operated at its maximum power point and the TEG system output power will therefore be higher. In this work a power converter based on noninverting buck-boost converters capable of handling four TEG modules is presented. It is shown that, when each module in the TEG system is operated under individual maximum power point tracking, the system output power for this specific application can be increased by up to 8.4% relative to the situation when the modules are connected in series and 16.7% relative to the situation when the modules are connected in parallel.
Efficiency at Maximum Power of Interacting Molecular Machines
Golubeva, Natalia; Imparato, Alberto
2012-01-01
We investigate the efficiency of systems of molecular motors operating at maximum power. We consider two models of kinesin motors on a microtubule: for both the simplified and the detailed model, we find that the many-body exclusion effect enhances the efficiency at maximum power of the many- motor...... system, with respect to the single motor case. Remarkably, we find that this effect occurs in a limited region of the system parameters, compatible with the biologically relevant range....
Parametric optimization of thermoelectric elements footprint for maximum power generation
Rezania, A.; Rosendahl, Lasse; Yin, Hao
2014-01-01
The development studies in thermoelectric generator (TEG) systems are mostly disconnected to parametric optimization of the module components. In this study, optimum footprint ratio of n- and p-type thermoelectric (TE) elements is explored to achieve maximum power generation, maximum cost-perform...
Maximum power point tracking for optimizing energy harvesting process
Akbari, S.; Thang, P. C.; Veselov, D. S.
2016-10-01
There has been a growing interest in using energy harvesting techniques for powering wireless sensor networks. The reason for utilizing this technology can be explained by the sensors limited amount of operation time which results from the finite capacity of batteries and the need for having a stable power supply in some applications. Energy can be harvested from the sun, wind, vibration, heat, etc. It is reasonable to develop multisource energy harvesting platforms for increasing the amount of harvesting energy and to mitigate the issue concerning the intermittent nature of ambient sources. In the context of solar energy harvesting, it is possible to develop algorithms for finding the optimal operation point of solar panels at which maximum power is generated. These algorithms are known as maximum power point tracking techniques. In this article, we review the concept of maximum power point tracking and provide an overview of the research conducted in this area for wireless sensor networks applications.
A Maximum Power Tracker for Improved Thermophotovoltaic Power Generation Project
National Aeronautics and Space Administration — Radioisotope Power Systems (RPS) are critical for future flagship exploration missions in space and on planetary surfaces. Small improvements in the RPS performance,...
2010-07-01
... as specified in 40 CFR 1065.610. This is the maximum in-use engine speed used for calculating the NOX... procedures of 40 CFR part 1065, based on the manufacturer's design and production specifications for the..., power density, and maximum in-use engine speed. 1042.140 Section 1042.140 Protection of...
Size dependence of efficiency at maximum power of heat engine
Izumida, Y.
2013-10-01
We perform a molecular dynamics computer simulation of a heat engine model to study how the engine size difference affects its performance. Upon tactically increasing the size of the model anisotropically, we determine that there exists an optimum size at which the model attains the maximum power for the shortest working period. This optimum size locates between the ballistic heat transport region and the diffusive heat transport one. We also study the size dependence of the efficiency at the maximum power. Interestingly, we find that the efficiency at the maximum power around the optimum size attains a value that has been proposed as a universal upper bound, and it even begins to exceed the bound as the size further increases. We explain this behavior of the efficiency at maximum power by using a linear response theory for the heat engine operating under a finite working period, which naturally extends the low-dissipation Carnot cycle model [M. Esposito, R. Kawai, K. Lindenberg, C. Van den Broeck, Phys. Rev. Lett. 105, 150603 (2010)]. The theory also shows that the efficiency at the maximum power under an extreme condition may reach the Carnot efficiency in principle.© EDP Sciences Società Italiana di Fisica Springer-Verlag 2013.
Investigation on the Maximum Power Point in Solar Panel Characteristics Due to Irradiance Changes
Abdullah, M. A.; Fauziah Toha, Siti; Ahmad, Salmiah
2017-03-01
One of the disadvantages of the photovoltaic module as compared to other renewable resources is the dynamic characteristics of solar irradiance due to inconsistency weather condition and surrounding temperature. Commonly, a photovoltaic power generation systems consist of an embedded control system to maximize the power generation due to the inconsistency in irradiance. In order to improve the simplicity of the power optimization control, this paper present the characteristic of Maximum Power Point with various irradiance levels for Maximum Power Point Tracking (MPPT). The technique requires a set of data from photovoltaic simulation model to be extrapolated as a standard relationship between irradiance and maximum power. The result shows that the relationship between irradiance and maximum power can be represented by a simplified quadratic equation. The first section in your paper
Beat the Deviations in Estimating Maximum Power of Thermoelectric Modules
Gao, Junling; Chen, Min
2013-01-01
Under a certain temperature difference, the maximum power of a thermoelectric module can be estimated by the open-circuit voltage and the short-circuit current. In practical measurement, there exist two switch modes, either from open to short or from short to open, but the two modes can give...... different estimations on the maximum power. Using TEG-127-2.8-3.5-250 and TEG-127-1.4-1.6-250 as two examples, the difference is about 10%, leading to some deviations with the temperature change. This paper analyzes such differences by means of a nonlinear numerical model of thermoelectricity, and finds out...
Efficiency of autonomous soft nanomachines at maximum power.
Seifert, Udo
2011-01-14
We consider nanosized artificial or biological machines working in steady state enforced by imposing nonequilibrium concentrations of solutes or by applying external forces, torques, or electric fields. For unicyclic and strongly coupled multicyclic machines, efficiency at maximum power is not bounded by the linear response value 1/2. For strong driving, it can even approach the thermodynamic limit 1. Quite generally, such machines fall into three different classes characterized, respectively, as "strong and efficient," "strong and inefficient," and "balanced." For weakly coupled multicyclic machines, efficiency at maximum power has lost any universality even in the linear response regime.
Maximum Power Point Tracking Based on Sliding Mode Control
Nimrod Vázquez
2015-01-01
Full Text Available Solar panels, which have become a good choice, are used to generate and supply electricity in commercial and residential applications. This generated power starts with the solar cells, which have a complex relationship between solar irradiation, temperature, and output power. For this reason a tracking of the maximum power point is required. Traditionally, this has been made by considering just current and voltage conditions at the photovoltaic panel; however, temperature also influences the process. In this paper the voltage, current, and temperature in the PV system are considered to be a part of a sliding surface for the proposed maximum power point tracking; this means a sliding mode controller is applied. Obtained results gave a good dynamic response, as a difference from traditional schemes, which are only based on computational algorithms. A traditional algorithm based on MPPT was added in order to assure a low steady state error.
Efficiency at maximum power of thermally coupled heat engines.
Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph
2012-04-01
We study the efficiency at maximum power of two coupled heat engines, using thermoelectric generators (TEGs) as engines. Assuming that the heat and electric charge fluxes in the TEGs are strongly coupled, we simulate numerically the dependence of the behavior of the global system on the electrical load resistance of each generator in order to obtain the working condition that permits maximization of the output power. It turns out that this condition is not unique. We derive a simple analytic expression giving the relation between the electrical load resistance of each generator permitting output power maximization. We then focus on the efficiency at maximum power (EMP) of the whole system to demonstrate that the Curzon-Ahlborn efficiency may not always be recovered: The EMP varies with the specific working conditions of each generator but remains in the range predicted by irreversible thermodynamics theory. We discuss our results in light of nonideal Carnot engine behavior.
Quantum-dot Carnot engine at maximum power.
Esposito, Massimiliano; Kawai, Ryoichi; Lindenberg, Katja; Van den Broeck, Christian
2010-04-01
We evaluate the efficiency at maximum power of a quantum-dot Carnot heat engine. The universal values of the coefficients at the linear and quadratic order in the temperature gradient are reproduced. Curzon-Ahlborn efficiency is recovered in the limit of weak dissipation.
Accurate Maximum Power Tracking in Photovoltaic Systems Affected by Partial Shading
Pierluigi Guerriero
2015-01-01
Full Text Available A maximum power tracking algorithm exploiting operating point information gained on individual solar panels is presented. The proposed algorithm recognizes the presence of multiple local maxima in the power voltage curve of a shaded solar field and evaluates the coordinated of the absolute maximum. The effectiveness of the proposed approach is evidenced by means of circuit level simulation and experimental results. Experiments evidenced that, in comparison with a standard perturb and observe algorithm, we achieve faster convergence in normal operating conditions (when the solar field is uniformly illuminated and we accurately locate the absolute maximum power point in partial shading conditions, thus avoiding the convergence on local maxima.
An improved maximum power point tracking method for photovoltaic systems
Tafticht, T.; Agbossou, K.; Doumbia, M.L.; Cheriti, A. [Institut de recherche sur l' hydrogene, Departement de genie electrique et genie informatique, Universite du Quebec a Trois-Rivieres, C.P. 500, Trois-Rivieres (QC) (Canada)
2008-07-15
In most of the maximum power point tracking (MPPT) methods described currently in the literature, the optimal operation point of the photovoltaic (PV) systems is estimated by linear approximations. However these approximations can lead to less than optimal operating conditions and hence reduce considerably the performances of the PV system. This paper proposes a new approach to determine the maximum power point (MPP) based on measurements of the open-circuit voltage of the PV modules, and a nonlinear expression for the optimal operating voltage is developed based on this open-circuit voltage. The approach is thus a combination of the nonlinear and perturbation and observation (P and O) methods. The experimental results show that the approach improves clearly the tracking efficiency of the maximum power available at the output of the PV modules. The new method reduces the oscillations around the MPP, and increases the average efficiency of the MPPT obtained. The new MPPT method will deliver more power to any generic load or energy storage media. (author)
Y. Labbi
2015-08-01
Full Text Available Photovoltaic electricity is seen as an important source of renewable energy. The photovoltaic array is an unstable source of power since the peak power point depends on the temperature and the irradiation level. A maximum peak power point tracking is then necessary for maximum efficiency.In this work, a Particle Swarm Optimization (PSO is proposed for maximum power point tracker for photovoltaic panel, are used to generate the optimal MPP, such that solar panel maximum power is generated under different operating conditions. A photovoltaic system including a solar panel and PSO MPP tracker is modelled and simulated, it has been has been carried out which has shown the effectiveness of PSO to draw much energy and fast response against change in working conditions.
Efficiency at maximum power of a discrete feedback ratchet
Jarillo, Javier; Tangarife, Tomás; Cao, Francisco J.
2016-01-01
Efficiency at maximum power is found to be of the same order for a feedback ratchet and for its open-loop counterpart. However, feedback increases the output power up to a factor of five. This increase in output power is due to the increase in energy input and the effective entropy reduction obtained as a consequence of feedback. Optimal efficiency at maximum power is reached for time intervals between feedback actions two orders of magnitude smaller than the characteristic time of diffusion over a ratchet period length. The efficiency is computed consistently taking into account the correlation between the control actions. We consider a feedback control protocol for a discrete feedback flashing ratchet, which works against an external load. We maximize the power output optimizing the parameters of the ratchet, the controller, and the external load. The maximum power output is found to be upper bounded, so the attainable extracted power is limited. After, we compute an upper bound for the efficiency of this isothermal feedback ratchet at maximum power output. We make this computation applying recent developments of the thermodynamics of feedback-controlled systems, which give an equation to compute the entropy reduction due to information. However, this equation requires the computation of the probability of each of the possible sequences of the controller's actions. This computation becomes involved when the sequence of the controller's actions is non-Markovian, as is the case in most feedback ratchets. We here introduce an alternative procedure to set strong bounds to the entropy reduction in order to compute its value. In this procedure the bounds are evaluated in a quasi-Markovian limit, which emerge when there are big differences between the stationary probabilities of the system states. These big differences are an effect of the potential strength, which minimizes the departures from the Markovianicity of the sequence of control actions, allowing also to
Maximum-power quantum-mechanical Carnot engine.
Abe, Sumiyoshi
2011-04-01
In their work [J. Phys. A 33, 4427 (2000)], Bender, Brody, and Meister have shown by employing a two-state model of a particle confined in the one-dimensional infinite potential well that it is possible to construct a quantum-mechanical analog of the Carnot engine through changes of both the width of the well and the quantum state in a specific manner. Here, a discussion is developed about realizing the maximum power of such an engine, where the width of the well moves at low but finite speed. The efficiency of the engine at the maximum power output is found to be universal independently of any of the parameters contained in the model.
Novel TPPO Based Maximum Power Point Method for Photovoltaic System
ABBASI, M. A.
2017-08-01
Full Text Available Photovoltaic (PV system has a great potential and it is installed more when compared with other renewable energy sources nowadays. However, the PV system cannot perform optimally due to its solid reliance on climate conditions. Due to this dependency, PV system does not operate at its maximum power point (MPP. Many MPP tracking methods have been proposed for this purpose. One of these is the Perturb and Observe Method (P&O which is the most famous due to its simplicity, less cost and fast track. But it deviates from MPP in continuously changing weather conditions, especially in rapidly changing irradiance conditions. A new Maximum Power Point Tracking (MPPT method, Tetra Point Perturb and Observe (TPPO, has been proposed to improve PV system performance in changing irradiance conditions and the effects on characteristic curves of PV array module due to varying irradiance are delineated. The Proposed MPPT method has shown better results in increasing the efficiency of a PV system.
Variable structure control for maximum wind power extraction
Barambones, O.; Gonzalez de Durana, J.M.; Alcorta, P. [Univ. of the Basque Country, Vitoria (Spain)
2009-07-01
The future development of wind power technology will affect the level of impact that wind power will have on the power system. Very large wind farms can pose complex technical challenges while also paving the way for other new technologies that will help with electric grid integration. Increasingly complicated power electronic and computerized control schemes will lead to significant improvements and full controllability of available wind power. Reactive power compensation is an important issue in the control of distribution and transmission systems as it increases feeder system losses, reduces system power factor, and can cause large-amplitude variations in load-side voltage. Moreover, rapid changes in the reactive power consumption of large load centers can cause voltage amplitude oscillations, leading to a change in the electric system real power demand resulting in power oscillation. This paper described a sliding mode vector control for a double fed induction generator (DFIG) drive, used in variable speed wind power generation. The study proposed a new variable structure control which has an integral sliding surface to relax the requirement of the acceleration signal, commonly used in conventional sliding mode speed control techniques. The paper discussed the system modelling, DFIG control scheme, and simulation results. A test of the proposed method based on a two-bladed horizontal axis wind turbine was conducted using the Matlab/Simulink software. In this test, several operating conditions were simulated and the study concluded that satisfactory results were obtained. 14 refs., 5 figs.
Maximum power point tracking of partially shaded solar photovoltaic arrays
Roy Chowdhury, Shubhajit; Saha, Hiranmay [IC Design and Fabrication Centre, Department of Electronics and Telecommunication Engineering, Jadavpur University (India)
2010-09-15
The paper presents the simulation and hardware implementation of maximum power point (MPP) tracking of a partially shaded solar photovoltaic (PV) array using a variant of Particle Swarm Optimization known as Adaptive Perceptive Particle Swarm Optimization (APPSO). Under partially shaded conditions, the photovoltaic (PV) array characteristics get more complex with multiple maxima in the power-voltage characteristic. The paper presents an algorithmic technique to accurately track the maximum power point (MPP) of a PV array using an APPSO. The APPSO algorithm has also been validated in the current work. The proposed technique uses only one pair of sensors to control multiple PV arrays. This result in lower cost and higher accuracy of 97.7% compared to earlier obtained accuracy of 96.41% using Particle Swarm Optimization. The proposed tracking technique has been mapped onto a MSP430FG4618 microcontroller for tracking and control purposes. The whole system based on the proposed has been realized on a standard two stage power electronic system configuration. (author)
Invulnerability of power grids based on maximum flow theory
Fan, Wenli; Huang, Shaowei; Mei, Shengwei
2016-11-01
The invulnerability analysis against cascades is of great significance in evaluating the reliability of power systems. In this paper, we propose a novel cascading failure model based on the maximum flow theory to analyze the invulnerability of power grids. In the model, node initial loads are built on the feasible flows of nodes with a tunable parameter γ used to control the initial node load distribution. The simulation results show that both the invulnerability against cascades and the tolerance parameter threshold αT are affected by node load distribution greatly. As γ grows, the invulnerability shows the distinct change rules under different attack strategies and different tolerance parameters α respectively. These results are useful in power grid planning and cascading failure prevention.
Small scale wind energy harvesting with maximum power tracking
Joaquim Azevedo
2015-07-01
Full Text Available It is well-known that energy harvesting from wind can be used to power remote monitoring systems. There are several studies that use wind energy in small-scale systems, mainly with wind turbine vertical axis. However, there are very few studies with actual implementations of small wind turbines. This paper compares the performance of horizontal and vertical axis wind turbines for energy harvesting on wireless sensor network applications. The problem with the use of wind energy is that most of the time the wind speed is very low, especially at urban areas. Therefore, this work includes a study on the wind speed distribution in an urban environment and proposes a controller to maximize the energy transfer to the storage systems. The generated power is evaluated by simulation and experimentally for different load and wind conditions. The results demonstrate the increase in efficiency of wind generators that use maximum power transfer tracking, even at low wind speeds.
A maximum power point tracking algorithm for photovoltaic applications
Nelatury, Sudarshan R.; Gray, Robert
2013-05-01
The voltage and current characteristic of a photovoltaic (PV) cell is highly nonlinear and operating a PV cell for maximum power transfer has been a challenge for a long time. Several techniques have been proposed to estimate and track the maximum power point (MPP) in order to improve the overall efficiency of a PV panel. A strategic use of the mean value theorem permits obtaining an analytical expression for a point that lies in a close neighborhood of the true MPP. But hitherto, an exact solution in closed form for the MPP is not published. This problem can be formulated analytically as a constrained optimization, which can be solved using the Lagrange method. This method results in a system of simultaneous nonlinear equations. Solving them directly is quite difficult. However, we can employ a recursive algorithm to yield a reasonably good solution. In graphical terms, suppose the voltage current characteristic and the constant power contours are plotted on the same voltage current plane, the point of tangency between the device characteristic and the constant power contours is the sought for MPP. It is subject to change with the incident irradiation and temperature and hence the algorithm that attempts to maintain the MPP should be adaptive in nature and is supposed to have fast convergence and the least misadjustment. There are two parts in its implementation. First, one needs to estimate the MPP. The second task is to have a DC-DC converter to match the given load to the MPP thus obtained. Availability of power electronics circuits made it possible to design efficient converters. In this paper although we do not show the results from a real circuit, we use MATLAB to obtain the MPP and a buck-boost converter to match the load. Under varying conditions of load resistance and irradiance we demonstrate MPP tracking in case of a commercially available solar panel MSX-60. The power electronics circuit is simulated by PSIM software.
2011-01-01
Single-stage grid-connected Photovoltaic (PV) systems have advantages such as simple topology, high efficiency, etc. However, since all the control objectives such as the maximum power point tracking (with the utility voltage, and harmonics reduction for output current need to be considered simultaneously, the complexity of the control scheme is much increased. In this paper a new type of grid connected photovoltaic (PV) system with Maximum Power Point Tracking (MPPT) and reactive power simul...
2014-01-01
The power converter is one of the essential elements for effective use of renewable power sources. This paper focuses on the development of a circuit simulation model for maximum power point tracking (MPPT) evaluation of solar power that involves using different buck-boost power converter topologies; including SEPIC, Zeta, and four-switch type buck-boost DC/DC converters. The circuit simulation model mainly includes three subsystems: a PV model; a buck-boost converter-based MPPT system; and ...
Effective soil hydraulic conductivity predicted with the maximum power principle
Westhoff, Martijn; Erpicum, Sébastien; Archambeau, Pierre; Pirotton, Michel; Zehe, Erwin; Dewals, Benjamin
2016-04-01
Drainage of water in soils happens for a large extent through preferential flowpaths, but these subsurface flowpaths are extremely difficult to observe or parameterize in hydrological models. To potentially overcome this problem, thermodynamic optimality principles have been suggested to predict effective parametrization of these (sub-grid) structures, such as the maximum entropy production principle or the equivalent maximum power principle. These principles have been successfully applied to predict heat transfer from the Equator to the Poles, or turbulent heat fluxes between the surface and the atmosphere. In these examples, the effective flux adapts itself to its boundary condition by adapting its effective conductance through the creation of e.g. convection cells. However, flow through porous media, such as soils, can only quickly adapt its effective flow conductance by creation of preferential flowpaths, but it is unknown if this is guided by the aim to create maximum power. Here we show experimentally that this is indeed the case: In the lab, we created a hydrological analogue to the atmospheric model dealing with heat transport between Equator and poles. The experimental setup consists of two freely draining reservoirs connected with each other by a confined aquifer. By adding water to only one reservoir, a potential difference will build up until a steady state is reached. From the steady state potential difference and the observed flow through the aquifer, and effective hydraulic conductance can be determined. This observed conductance does correspond to the one maximizing power of the flux through the confined aquifer. Although this experiment is done in an idealized setting, it opens doors for better parameterizing hydrological models. Furthermore, it shows that hydraulic properties of soils are not static, but they change with changing boundary conditions. A potential limitation to the principle is that it only applies to steady state conditions
Efficiency at maximum power of a chemical engine.
Hooyberghs, Hans; Cleuren, Bart; Salazar, Alberto; Indekeu, Joseph O; Van den Broeck, Christian
2013-10-01
A cyclically operating chemical engine is considered that converts chemical energy into mechanical work. The working fluid is a gas of finite-sized spherical particles interacting through elastic hard collisions. For a generic transport law for particle uptake and release, the efficiency at maximum power η(mp) [corrected] takes the form 1/2+cΔμ+O(Δμ(2)), with 1∕2 a universal constant and Δμ the chemical potential difference between the particle reservoirs. The linear coefficient c is zero for engines featuring a so-called left/right symmetry or particle fluxes that are antisymmetric in the applied chemical potential difference. Remarkably, the leading constant in η(mp) [corrected] is non-universal with respect to an exceptional modification of the transport law. For a nonlinear transport model, we obtain η(mp) = 1/(θ + 1) [corrected], with θ > 0 the power of Δμ in the transport equation.
Maximum Power Point Tracking of Photovoltaic System Using Intelligent Controller
Swathy C.S
2013-04-01
Full Text Available Photovoltaic systems normally use a maximum power point tracking (MPPT technique to continuously give forth the highest probable power to the load when the temperature and solar irradiationchanges occur. This subdues the problem of mismatch between the given load and the solar array. The energy conservation principle is used to obtain small signal model and transfer function. A simulationwork handling with MPPT controller, a DC/DC boost converter feeding a load is achieved. PI controller and fuzzy logic controllers were used as the MPPT controller, which controls the dc/dc converter. Simulations and experimental results showed excellent performance and were used for comparing PI controller and fuzzy logic controller.
Efficiency at maximum power of a chemical engine
Hooyberghs, Hans; Salazar, Alberto; Indekeu, Joseph O; Broeck, Christian Van den
2013-01-01
A cyclically operating chemical engine is considered that converts chemical energy into mechanical work. The working fluid is a gas of finite-sized spherical particles interacting through elastic hard collisions. For a generic transport law for particle uptake and release, the efficiency at maximum power $\\eta$ takes the form 1/2+c\\Delta \\mu + O(\\Delta \\mu^2), with 1/2 a universal constant and $\\Delta \\mu$ the chemical potential difference between the particle reservoirs. The linear coefficient c is zero for engines featuring a so-called left/right symmetry or particle fluxes that are antisymmetric in the applied chemical potential difference. Remarkably, the leading constant in $\\eta$ is non-universal with respect to an exceptional modification of the transport law. For a nonlinear transport model we obtain \\eta = 1/(\\theta +1), with \\theta >0 the power of $\\Delta \\mu$ in the transport equation
Maximum-power-point tracking control of solar heating system
Huang, Bin-Juine
2012-11-01
The present study developed a maximum-power point tracking control (MPPT) technology for solar heating system to minimize the pumping power consumption at an optimal heat collection. The net solar energy gain Q net (=Q s-W p/η e) was experimentally found to be the cost function for MPPT with maximum point. The feedback tracking control system was developed to track the optimal Q net (denoted Q max). A tracking filter which was derived from the thermal analytical model of the solar heating system was used to determine the instantaneous tracking target Q max(t). The system transfer-function model of solar heating system was also derived experimentally using a step response test and used in the design of tracking feedback control system. The PI controller was designed for a tracking target Q max(t) with a quadratic time function. The MPPT control system was implemented using a microprocessor-based controller and the test results show good tracking performance with small tracking errors. It is seen that the average mass flow rate for the specific test periods in five different days is between 18.1 and 22.9kg/min with average pumping power between 77 and 140W, which is greatly reduced as compared to the standard flow rate at 31kg/min and pumping power 450W which is based on the flow rate 0.02kg/sm 2 defined in the ANSI/ASHRAE 93-1986 Standard and the total collector area 25.9m 2. The average net solar heat collected Q net is between 8.62 and 14.1kW depending on weather condition. The MPPT control of solar heating system has been verified to be able to minimize the pumping energy consumption with optimal solar heat collection. © 2012 Elsevier Ltd.
Maximum Photovoltaic Penetration Levels on Typical Distribution Feeders: Preprint
Hoke, A.; Butler, R.; Hambrick, J.; Kroposki, B.
2012-07-01
This paper presents simulation results for a taxonomy of typical distribution feeders with various levels of photovoltaic (PV) penetration. For each of the 16 feeders simulated, the maximum PV penetration that did not result in steady-state voltage or current violation is presented for several PV location scenarios: clustered near the feeder source, clustered near the midpoint of the feeder, clustered near the end of the feeder, randomly located, and evenly distributed. In addition, the maximum level of PV is presented for single, large PV systems at each location. Maximum PV penetration was determined by requiring that feeder voltages stay within ANSI Range A and that feeder currents stay within the ranges determined by overcurrent protection devices. Simulations were run in GridLAB-D using hourly time steps over a year with randomized load profiles based on utility data and typical meteorological year weather data. For 86% of the cases simulated, maximum PV penetration was at least 30% of peak load.
21 CFR 801.415 - Maximum acceptable level of ozone.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Maximum acceptable level of ozone. 801.415 Section... level of ozone. (a) Ozone is a toxic gas with no known useful medical application in specific, adjunctive, or preventive therapy. In order for ozone to be effective as a germicide, it must be present in...
Maximum power analysis of photovoltaic module in Ramadi city
Shahatha Salim, Majid; Mohammed Najim, Jassim [College of Science, University of Anbar (Iraq); Mohammed Salih, Salih [Renewable Energy Research Center, University of Anbar (Iraq)
2013-07-01
Performance of photovoltaic (PV) module is greatly dependent on the solar irradiance, operating temperature, and shading. Solar irradiance can have a significant impact on power output of PV module and energy yield. In this paper, a maximum PV power which can be obtain in Ramadi city (100km west of Baghdad) is practically analyzed. The analysis is based on real irradiance values obtained as the first time by using Soly2 sun tracker device. Proper and adequate information on solar radiation and its components at a given location is very essential in the design of solar energy systems. The solar irradiance data in Ramadi city were analyzed based on the first three months of 2013. The solar irradiance data are measured on earth's surface in the campus area of Anbar University. Actual average data readings were taken from the data logger of sun tracker system, which sets to save the average readings for each two minutes and based on reading in each one second. The data are analyzed from January to the end of March-2013. Maximum daily readings and monthly average readings of solar irradiance have been analyzed to optimize the output of photovoltaic solar modules. The results show that the system sizing of PV can be reduced by 12.5% if a tracking system is used instead of fixed orientation of PV modules.
Maximum power analysis of photovoltaic module in Ramadi city
Majid Shahatha Salim, Jassim Mohammed Najim, Salih Mohammed Salih
2013-01-01
Full Text Available Performance of photovoltaic (PV module is greatly dependent on the solar irradiance, operating temperature, and shading. Solar irradiance can have a significant impact on power output of PV module and energy yield. In this paper, a maximum PV power which can be obtain in Ramadi city (100km west of Baghdad is practically analyzed. The analysis is based on real irradiance values obtained as the first time by using Soly2 sun tracker device. Proper and adequate information on solar radiation and its components at a given location is very essential in the design of solar energy systems. The solar irradiance data in Ramadi city were analyzed based on the first three months of 2013. The solar irradiance data are measured on earth's surface in the campus area of Anbar University. Actual average data readings were taken from the data logger of sun tracker system, which sets to save the average readings for each two minutes and based on reading in each one second. The data are analyzed from January to the end of March-2013. Maximum daily readings and monthly average readings of solar irradiance have been analyzed to optimize the output of photovoltaic solar modules. The results show that the system sizing of PV can be reduced by 12.5% if a tracking system is used instead of fixed orientation of PV modules.
Investigation of Maximum Power Point Tracking for Thermoelectric Generators
Phillip, Navneesh; Maganga, Othman; Burnham, Keith J.; Ellis, Mark A.; Robinson, Simon; Dunn, Julian; Rouaud, Cedric
2013-07-01
In this paper, a thermoelectric generator (TEG) model is developed as a tool for investigating optimized maximum power point tracking (MPPT) algorithms for TEG systems within automotive exhaust heat energy recovery applications. The model comprises three main subsystems that make up the TEG system: the heat exchanger, thermoelectric material, and power conditioning unit (PCU). In this study, two MPPT algorithms known as the perturb and observe (P&O) algorithm and extremum seeking control (ESC) are investigated. A synchronous buck-boost converter is implemented as the preferred DC-DC converter topology, and together with the MPPT algorithm completes the PCU architecture. The process of developing the subsystems is discussed, and the advantage of using the MPPT controller is demonstrated. The simulation results demonstrate that the ESC algorithm implemented in combination with a synchronous buck-boost converter achieves favorable power outputs for TEG systems. The appropriateness is by virtue of greater responsiveness to changes in the system's thermal conditions and hence the electrical potential difference generated in comparison with the P&O algorithm. The MATLAB/Simulink environment is used for simulation of the TEG system and comparison of the investigated control strategies.
Abhijit Sinha
2014-01-01
Full Text Available A comparative analysis on thermodynamic efficiency based on maximum power & power density conditions have been performed for a solar-driven Carnot heat engine with internal irreversibility. In this analysis, the heat transfer from the hot reservoir is to be in the radiation mode and the heat transfer to the cold reservoir is to be in the convection mode. The thermodynamic efficiency function, power & power density functions have been derived and maximization of the power functions have been performed for various design parameters. From the optimum conditions, the thermal efficiencies at maximum power and power densities have been obtained. The effects of internal irreversibility, extreme temperature ratios & specific engine size in area ratio between the hot & cold reservoirs as various design parameters on thermodynamic efficiencies have been investigated for both the conditions. The efficiencies have been compared with Curzon-Ahlborn & Carnot efficiencies respectively.The analysis showed that the efficiency at maximum power output is greater than the efficiency at maximum power density. And the efficiencies can be greater than the Curzon- Ahlborn`s efficiency only for low values of design parameters.
Maximum efficiency of low-dissipation heat engines at arbitrary power
Holubec, Viktor; Ryabov, Artem
2016-07-01
We investigate maximum efficiency at a given power for low-dissipation heat engines. Close to maximum power, the maximum gain in efficiency scales as a square root of relative loss in power and this scaling is universal for a broad class of systems. For low-dissipation engines, we calculate the maximum gain in efficiency for an arbitrary fixed power. We show that engines working close to maximum power can operate at considerably larger efficiency compared to the efficiency at maximum power. Furthermore, we introduce universal bounds on maximum efficiency at a given power for low-dissipation heat engines. These bounds represent direct generalization of the bounds on efficiency at maximum power obtained by Esposito et al (2010 Phys. Rev. Lett. 105 150603). We derive the bounds analytically in the regime close to maximum power and for small power values. For the intermediate regime we present strong numerical evidence for the validity of the bounds.
Efficiency at Maximum Power of Low-Dissipation Carnot Engines
Esposito, Massimiliano; Kawai, Ryoichi; Lindenberg, Katja; van den Broeck, Christian
2010-10-01
We study the efficiency at maximum power, η*, of engines performing finite-time Carnot cycles between a hot and a cold reservoir at temperatures Th and Tc, respectively. For engines reaching Carnot efficiency ηC=1-Tc/Th in the reversible limit (long cycle time, zero dissipation), we find in the limit of low dissipation that η* is bounded from above by ηC/(2-ηC) and from below by ηC/2. These bounds are reached when the ratio of the dissipation during the cold and hot isothermal phases tend, respectively, to zero or infinity. For symmetric dissipation (ratio one) the Curzon-Ahlborn efficiency ηCA=1-Tc/Th is recovered.
Hardware Implementation of Maximum Power Point Tracking for Thermoelectric Generators
Maganga, Othman; Phillip, Navneesh; Burnham, Keith J.; Montecucco, Andrea; Siviter, Jonathan; Knox, Andrew; Simpson, Kevin
2014-06-01
This work describes the practical implementation of two maximum power point tracking (MPPT) algorithms, namely those of perturb and observe, and extremum seeking control. The proprietary dSPACE system is used to perform hardware in the loop (HIL) simulation whereby the two control algorithms are implemented using the MATLAB/Simulink (Mathworks, Natick, MA) software environment in order to control a synchronous buck-boost converter connected to two commercial thermoelectric modules. The process of performing HIL simulation using dSPACE is discussed, and a comparison between experimental and simulated results is highlighted. The experimental results demonstrate the validity of the two MPPT algorithms, and in conclusion the benefits and limitations of real-time implementation of MPPT controllers using dSPACE are discussed.
Efficiency at maximum power of low-dissipation Carnot engines.
Esposito, Massimiliano; Kawai, Ryoichi; Lindenberg, Katja; Van den Broeck, Christian
2010-10-01
We study the efficiency at maximum power, η*, of engines performing finite-time Carnot cycles between a hot and a cold reservoir at temperatures Th and Tc, respectively. For engines reaching Carnot efficiency ηC=1-Tc/Th in the reversible limit (long cycle time, zero dissipation), we find in the limit of low dissipation that η* is bounded from above by ηC/(2-ηC) and from below by ηC/2. These bounds are reached when the ratio of the dissipation during the cold and hot isothermal phases tend, respectively, to zero or infinity. For symmetric dissipation (ratio one) the Curzon-Ahlborn efficiency ηCA=1-√Tc/Th] is recovered.
Meng-Hui Wang
2015-08-01
Full Text Available Sliding mode strategy (SMS for maximum power point tracking (MPPT is used in this study of a human power generation system. This approach ensures maximum power at different rotation speeds to increase efficiency and corrects for the lack of robustness in traditional methods. The intelligent extension theory is used to reduce input saturation and high frequency switching in sliding mode strategy, as well as to increase the efficiency and response speed. The experimental results show that the efficiency of the extension SMS (ESMS is 5% higher than in traditional SMS, and the response is 0.5 s faster.
Park, Hyunbin; Sim, Minseob; Kim, Shiho
2015-06-01
We propose a way of achieving maximum power and power-transfer efficiency from thermoelectric generators by optimized selection of maximum-power-point-tracking (MPPT) circuits composed of a boost-cascaded-with-buck converter. We investigated the effect of switch resistance on the MPPT performance of thermoelectric generators. The on-resistances of the switches affect the decrease in the conversion gain and reduce the maximum output power obtainable. Although the incremental values of the switch resistances are small, the resulting difference in the maximum duty ratio between the input and output powers is significant. For an MPPT controller composed of a boost converter with a practical nonideal switch, we need to monitor the output power instead of the input power to track the maximum power point of the thermoelectric generator. We provide a design strategy for MPPT controllers by considering the compromise in which a decrease in switch resistance causes an increase in the parasitic capacitance of the switch.
Jaw-Kuen Shiau
2014-08-01
Full Text Available The power converter is one of the essential elements for effective use of renewable power sources. This paper focuses on the development of a circuit simulation model for maximum power point tracking (MPPT evaluation of solar power that involves using different buck-boost power converter topologies; including SEPIC, Zeta, and four-switch type buck-boost DC/DC converters. The circuit simulation model mainly includes three subsystems: a PV model; a buck-boost converter-based MPPT system; and a fuzzy logic MPPT controller. Dynamic analyses of the current-fed buck-boost converter systems are conducted and results are presented in the paper. The maximum power point tracking function is achieved through appropriate control of the power switches of the power converter. A fuzzy logic controller is developed to perform the MPPT function for obtaining maximum power from the PV panel. The MATLAB-based Simulink piecewise linear electric circuit simulation tool is used to verify the complete circuit simulation model.
Effects of loading and size on maximum power output and gait characteristics in geckos.
Irschick, Duncan J; Vanhooydonck, Bieke; Herrel, Anthony; Andronescu, Anemone
2003-11-01
Stride length, stride frequency and power output are all factors influencing locomotor performance. Here, we first test whether mass-specific power output limits climbing performance in two species of geckos (Hemidactylus garnoti and Gekko gecko) by adding external loads to their bodies. We then test whether body size has a negative effect on mass-specific power output. Finally, we test whether loading affects kinematics in both gecko species. Lizards were induced to run vertically on a smooth wooden surface with loads of 0-200% of body mass (BM) in H. garnoti and 0-100% BM in G. gecko. For each stride, we calculated angular and linear kinematics (e.g. trunk angle, stride length), performance (maximum speed) and mean mass-specific power output per stride. The addition of increasingly large loads caused an initial increase in maximum mass-specific power output in both species, but for H. garnoti, mass-specific power output remained constant at higher loads (150% and 200% BM), even though maximum velocity declined. This result, in combination with the fact that stride frequency showed no evidence of leveling off as speed increased in either species, suggests that power limits maximum speed. In addition, the large gecko (G. gecko) produced significantly less power than the smaller H. garnoti, despite the fact that both species ran at similar speeds. This difference disappeared, however, when we recalculated power output based on higher maximum speeds for unloaded G. gecko moving vertically obtained by other researchers. Finally, the addition of external loads did not affect speed modulation in either species: both G. gecko and H. garnoti increase speed primarily by increasing stride frequency, regardless of loading condition. For a given speed, both species take shorter but more strides with heavier loads, but for a given load, G. gecko attains similar speeds to H. garnoti by taking longer but fewer strides.
The Power Reserves Market Creation For The Participants Maximum Benefit
Anatolij Mahnitko
2008-05-01
Full Text Available It is known, that the main task of the electric power system (EPS control is the power supply providing with the minimum expenses for the electric power production. In this case the requirement to the electric power quality, power supply reliability and the limitationson the energy resources cost must be observed. The power reserve presence into EPS is the necessary condition of the guaranteeing the normal operation from the point of view of the regime parameters values. In the proposed paper the problem of the developing the power reserve, presented to sale by the electric power producers, is examined. It is considered the procedure of the power reserve pricedetermination.
Chen-Han Wu
2011-12-01
Full Text Available Due to Japan’s recent nuclear crisis and petroleum price hikes, the search for renewable energy sources has become an issue of immediate concern. A promising candidate attracting much global attention is solar energy, as it is green and also inexhaustible. A maximum power point tracking (MPPT controller is employed in such a way that the output power provided by a photovoltaic (PV system is boosted to its maximum level. However, in the context of abrupt changes in irradiance, conventional MPPT controller approaches suffer from insufficient robustness against ambient variation, inferior transient response and a loss of output power as a consequence of the long duration required of tracking procedures. Accordingly, in this work the maximum power point tracking is carried out successfully using a sliding mode extremum-seeking control (SMESC method, and the tracking performances of three controllers are compared by simulations, that is, an extremum-seeking controller, a sinusoidal extremum-seeking controller and a sliding mode extremum-seeking controller. Being able to track the maximum power point promptly in the case of an abrupt change in irradiance, the SMESC approach is proven by simulations to be superior in terms of system dynamic and steady state responses, and an excellent robustness along with system stability is demonstrated as well.
Y. Hoseynpoor
2011-12-01
Full Text Available Single-stage grid-connected Photovoltaic (PV systems have advantages such as simple topology, high efficiency, etc. However, since all the control objectives such as the maximum power point tracking (with the utility voltage, and harmonics reduction for output current need to be considered simultaneously, the complexity of the control scheme is much increased. In this paper a new type of grid connected photovoltaic (PV system with Maximum Power Point Tracking (MPPT and reactive power simultaneous control system is presented. System has two controlling loops to obtain the maximum power from the PV array and also has reactive power control (RPC. In order to decrease the complexity, cost and the number of converters, a singlestage PV system is applied. Using RPC and MPPT controllers, reference current is calculated and the current with low THD (<5% is injected to grid through Adaptive Predictive Current Control (APCC and current Controlled Voltage Source Inverter (CCVSI. The operation of the system is classified in to two day and night modes. In day mode MPPT and RPC control is accomplished and in night mode RPC control is accomplished like STATCOM operation. Reactive power control is continuously performed correctly with appropriate speed in two inductive and capacitive modes in both day and night modes. Thus, System Utilization Factor (SUF increases to 100% which is just 20% for common PV systems. Mathematical modeling of the system and the results of simulations in MATLAB/SIMULINK software are presented to investigate the correctness of the results.
PV Maximum Power-Point Tracking by Using Artificial Neural Network
Farzad Sedaghati; Ali Nahavandi; Mohammad Ali Badamchizadeh; Sehraneh Ghaemi; Mehdi Abedinpour Fallah
2012-01-01
In this paper, using artificial neural network (ANN) for tracking of maximum power point is discussed. Error back propagation method is used in order to train neural network. Neural network has advantages of fast and precisely tracking of maximum power point. In this method neural network is used to specify the reference voltage of maximum power point under different atmospheric conditions. By properly controling of dc-dc boost converter, tracking of maximum power point is feasible. To verify...
Estimation of Maximum Allowable PV Connection to LV Residential Power Networks
Demirok, Erhan; Sera, Dezso; Teodorescu, Remus
2011-01-01
transformer or using solar inverters with new grid support features. This study presents a methodology for the estimation of maximum PV hosting capacity including IEC 60076-7 based thermal model of distribution transformer. Certain part of a real distribution network of Braedstrup suburban area in Denmark...... is used in simulation as a case study model. Furthermore, varying solutions (utilizing thermally upgraded insulation paper in transformers, reactive power services from solar inverters, etc.) are implemented on the network under investigation to examine PV penetration level and finally key results learnt......Maximum photovoltaic (PV) hosting capacity of low voltage (LV) power networks is mainly restricted by either thermal limits of network components or grid voltage quality resulted from high penetration of distributed PV systems. This maximum hosting capacity may be lower than the available solar...
Projective Power Entropy and Maximum Tsallis Entropy Distributions
Shinto Eguchi; Shogo Kato; Osamu Komori
2011-01-01
We discuss a one-parameter family of generalized cross entropy between two distributions with the power index, called the projective power entropy. The cross entropy is essentially reduced to the Tsallis entropy if two distributions are taken to be equal. Statistical and probabilistic properties associated with the projective power entropy are extensively investigated including a characterization problem of which conditions uniquely determine the projective power entropy up to the power index...
Unbounded Binary Search for a Fast and Accurate Maximum Power Point Tracking
Kim, Yong Sin; Winston, Roland
2011-12-01
This paper presents a technique for maximum power point tracking (MPPT) of a concentrating photovoltaic system using cell level power optimization. Perturb and observe (P&O) has been a standard for an MPPT, but it introduces a tradeoff between the tacking speed and the accuracy of the maximum power delivered. The P&O algorithm is not suitable for a rapid environmental condition change by partial shading and self-shading due to its tracking time being linear to the length of the voltage range. Some of researches have been worked on fast tracking but they come with internal ad hoc parameters. In this paper, by using the proposed unbounded binary search algorithm for the MPPT, tracking time becomes a logarithmic function of the voltage search range without ad hoc parameters.
Chen, Jincan; Yan, Zijun; Wu, Liqing
1996-06-01
Considering a thermoelectric generator as a heat engine cycle, the general differential equations of the temperature field inside thermoelectric elements are established by means of nonequilibrium thermodynamics. These equations are used to study the influence of heat leak, Joule's heat, and Thomson heat on the performance of the thermoelectric generator. New expressions are derived for the power output and the efficiency of the thermoelectric generator. The maximum power output is calculated and the optimal matching condition of load is determined. The maximum efficiency is discussed by a representative numerical example. The aim of this research is to provide some novel conclusions and redress some errors existing in a related investigation.
Forecasting ozone daily maximum levels at Santiago, Chile
Jorquera, Héctor; Pérez, Ricardo; Cipriano, Aldo; Espejo, Andrés; Victoria Letelier, M.; Acuña, Gonzalo
In major urban areas, air pollution impact on health is serious enough to include it in the group of meteorological variables that are forecast daily. This work focusses on the comparison of different forecasting systems for daily maximum ozone levels at Santiago, Chile. The modelling tools used for these systems were linear time series, artificial neural networks and fuzzy models. The structure of the forecasting model was derived from basic principles and it includes a combination of persistence and daily maximum air temperature as input variables. Assessment of the models is based on two indices: their ability to forecast well an episode, and their tendency to forecast an episode that did not occur at the end (a false positive). All the models tried in this work showed good forecasting performance, with 70-95% of successful forecasts at two monitor sites: Downtown (moderate impacts) and Eastern (downwind, highest impacts). The number of false positives was not negligible, but this may be improved by expressing the forecast in broad classes: low, average, high, very high impacts; the fuzzy model was the most reliable forecast, with the lowest number of false positives among the different models evaluated. The quality of the results and the dynamics of ozone formation suggest the use of a forecast to warn people about excessive exposure during episodic days at Santiago.
A hybrid solar panel maximum power point search method that uses light and temperature sensors
Ostrowski, Mariusz
2016-04-01
Solar cells have low efficiency and non-linear characteristics. To increase the output power solar cells are connected in more complex structures. Solar panels consist of series of connected solar cells with a few bypass diodes, to avoid negative effects of partial shading conditions. Solar panels are connected to special device named the maximum power point tracker. This device adapt output power from solar panels to load requirements and have also build in a special algorithm to track the maximum power point of solar panels. Bypass diodes may cause appearance of local maxima on power-voltage curve when the panel surface is illuminated irregularly. In this case traditional maximum power point tracking algorithms can find only a local maximum power point. In this article the hybrid maximum power point search algorithm is presented. The main goal of the proposed method is a combination of two algorithms: a method that use temperature sensors to track maximum power point in partial shading conditions and a method that use illumination sensor to track maximum power point in equal illumination conditions. In comparison to another methods, the proposed algorithm uses correlation functions to determinate the relationship between values of illumination and temperature sensors and the corresponding values of current and voltage in maximum power point. In partial shading condition the algorithm calculates local maximum power points bases on the value of temperature and the correlation function and after that measures the value of power on each of calculated point choose those with have biggest value, and on its base run the perturb and observe search algorithm. In case of equal illumination algorithm calculate the maximum power point bases on the illumination value and the correlation function and on its base run the perturb and observe algorithm. In addition, the proposed method uses a special coefficient modification of correlation functions algorithm. This sub
Mroczka Janusz
2014-12-01
Full Text Available Photovoltaic panels have a non-linear current-voltage characteristics to produce the maximum power at only one point called the maximum power point. In the case of the uniform illumination a single solar panel shows only one maximum power, which is also the global maximum power point. In the case an irregularly illuminated photovoltaic panel many local maxima on the power-voltage curve can be observed and only one of them is the global maximum. The proposed algorithm detects whether a solar panel is in the uniform insolation conditions. Then an appropriate strategy of tracking the maximum power point is taken using a decision algorithm. The proposed method is simulated in the environment created by the authors, which allows to stimulate photovoltaic panels in real conditions of lighting, temperature and shading.
Design of wind turbine airfoils based on maximum power coefficient
Chen, Jin; Cheng, Jiangtao; Shen, Wenzhong;
2010-01-01
noise prediction model, the previously developed integrated design technique is further developed. The new code takes into account different airfoil requirements according to their local positions on a blade, such as sensitivity to leading edge roughness, design lift at off-design condition, stall......Based on the blade element momentum (BEM) theory, the power coefficient of a wind turbine can be expressed in function of local tip speed ratio and lift-drag ratio. By taking the power coefficient in a predefined range of angle of attack as the final design objective and combining with an airfoil...
H. Ijadi
2012-09-01
Full Text Available In this paper, a method to track the maximum power of solar panels based on fuzzy logic is presented. The proposed method is based on the relationship between radiation intensity and the voltage of maximum power operating point. With this relationship, at any time by measuring the light intensity, voltage can be calculated at the maximum power point by using fuzzy approximation function. In order to verify the proposed method, simulation results are presented.
Power optimization for maximum channel capacity in MIMO relay system
无
2007-01-01
Introducing multiple-input multiple-output (MIMO) relay channel could offer significant capacity gain.And it is of great importance to develop effective power allocation strategies to achieve power efficiency and improve channel capacity in amplify-and-forward relay system.This article investigates a two-hop MIMO relay system with multiple antennas in relay node (RN) and receiver (RX).Maximizing capacity with antenna selection (MCAS) and maximizing capacity with eigen-decomposition (MCED) schemes are proposed to efficiently allocate power among antennas in RN under first and second hop limited scenarios.The analysis and simulation results show that both MCED and MCAS can improve the channel capacity compared with uniform power allocation (UPA) scheme in most of the studied areas.The MCAS bears comparison with MCED with an acceptable capacity loss, but lowers the complexity by saving channel state information (CSI) feedback to the transmitter (TX).Moreover, when the RN is close to RX, the performance of UPA is also close to the upper bound as the performance of first hop is limited.
GA-BASED MAXIMUM POWER DISSIPATION ESTIMATION OF VLSI SEQUENTIAL CIRCUITS OF ARBITRARY DELAY MODELS
Lu Junming; Lin Zhenghui
2002-01-01
In this paper, the glitching activity and process variations in the maximum power dissipation estimation of CMOS circuits are introduced. Given a circuit and the gate library,a new Genetic Algorithm (GA)-based technique is developed to determine the maximum power dissipation from a statistical point of view. The simulation on ISCAS-89 benchmarks shows that the ratio of the maximum power dissipation with glitching activity over the maximum power under zero-delay model ranges from 1.18 to 4.02. Compared with the traditional Monte Carlo-based technique, the new approach presented in this paper is more effective.
GA—BASED MAXIMUM POWER DISSIPATION ESTIMATION OF VLSI SEQUENTIAL CIRCUITS OF ARBITRARY DELAY MODELS
LuJunming; LinZhenghui
2002-01-01
In this paper,the glitching activity and process variations in the maximum power dissipation estimation of CMOS circulits are introduced.Given a circuit and the gate library,a new Genetic Algorithm (GA)-based technique is developed to determine the maximum power dissipation from a statistical point of view.The simulation on ISCAS-89 benchmarks shows that the ratio of the maximum power dissipation with glitching activity over the maximum power under zero-delay model ranges from 1.18 to 4.02.Compared with the traditional Monte Carlo-based technique,the new approach presented in this paper is more effective.
PV Maximum Power-Point Tracking by Using Artificial Neural Network
Farzad Sedaghati
2012-01-01
Full Text Available In this paper, using artificial neural network (ANN for tracking of maximum power point is discussed. Error back propagation method is used in order to train neural network. Neural network has advantages of fast and precisely tracking of maximum power point. In this method neural network is used to specify the reference voltage of maximum power point under different atmospheric conditions. By properly controling of dc-dc boost converter, tracking of maximum power point is feasible. To verify theory analysis, simulation result is obtained by using MATLAB/SIMULINK.
Maximum Power Output of Quantum Heat Engine with Energy Bath
Liu, Shengnan
2016-01-01
The difference between quantum isoenergetic process and quantum isothermal process comes from the violation of the law of equipartition of energy in the quantum regime. To reveal an important physical meaning of this fact, here we study a special type of quantum heat engine consisting of three processes: isoenergetic, isothermal and adiabatic processes. Therefore, this engine works between the energy and heat baths. Combining two engines of this kind, it is possible to realize the quantum Carnot engine. Furthermore, considering finite velocity of change of the potential shape, here an infinite square well with moving walls, the power output of the engine is discussed. It is found that the efficiency and power output are both closely dependent on the initial and final states of the quantum isothermal process. The performance of the engine cycle is shown to be optimized by control of the occupation probability of the ground state, which is determined by the temperature and the potential width. The relation betw...
Maximum Power Output of Quantum Heat Engine with Energy Bath
Shengnan Liu
2016-05-01
Full Text Available The difference between quantum isoenergetic process and quantum isothermal process comes from the violation of the law of equipartition of energy in the quantum regime. To reveal an important physical meaning of this fact, here we study a special type of quantum heat engine consisting of three processes: isoenergetic, isothermal and adiabatic processes. Therefore, this engine works between the energy and heat baths. Combining two engines of this kind, it is possible to realize the quantum Carnot engine. Furthermore, considering finite velocity of change of the potential shape, here an infinite square well with moving walls, the power output of the engine is discussed. It is found that the efficiency and power output are both closely dependent on the initial and final states of the quantum isothermal process. The performance of the engine cycle is shown to be optimized by control of the occupation probability of the ground state, which is determined by the temperature and the potential width. The relation between the efficiency and power output is also discussed.
Mohsen Taherbaneh; A. H. Rezaie; H. Ghafoorifard; Rahimi, K; M. B. Menhaj
2010-01-01
In applications with low-energy conversion efficiency, maximizing the output power improves the efficiency. The maximum output power of a solar panel depends on the environmental conditions and load profile. In this paper, a method based on simultaneous use of two fuzzy controllers is developed in order to maximize the generated output power of a solar panel in a photovoltaic system: fuzzy-based sun tracking and maximum power point tracking. The sun tracking is performed by changing the solar...
Reliability of the one-repetition-maximum power clean test in adolescent athletes.
Faigenbaum, Avery D; McFarland, James E; Herman, Robert E; Naclerio, Fernando; Ratamess, Nicholas A; Kang, Jie; Myer, Gregory D
2012-02-01
Although the power clean test is routinely used to assess strength and power performance in adult athletes, the reliability of this measure in younger populations has not been examined. Therefore, the purpose of this study was to determine the reliability of the 1-repetition maximum (1RM) power clean in adolescent athletes. Thirty-six male athletes (age 15.9 ± 1.1 years, body mass 79.1 ± 20.3 kg, height 175.1 ±7.4 cm) who had >1 year of training experience in weightlifting exercises performed a 1RM power clean on 2 nonconsecutive days in the afternoon following standardized procedures. All test procedures were supervised by a senior level weightlifting coach and consisted of a systematic progression in test load until the maximum resistance that could be lifted for 1 repetition using proper exercise technique was determined. Data were analyzed using an intraclass correlation coefficient (ICC[2,k]), Pearson correlation coefficient (r), repeated measures analysis of variance, Bland-Altman plot, and typical error analyses. Analysis of the data revealed that the test measures were highly reliable demonstrating a test-retest ICC of 0.98 (95% confidence interval = 0.96-0.99). Testing also demonstrated a strong relationship between 1RM measures in trials 1 and 2 (r = 0.98, p adolescent athletes when standardized testing procedures are followed and qualified instruction is present.
RELIABILITY OF THE ONE REPETITION-MAXIMUM POWER CLEAN TEST IN ADOLESCENT ATHLETES
Faigenbaum, Avery D.; McFarland, James E.; Herman, Robert; Naclerio, Fernando; Ratamess, Nicholas A.; Kang, Jie; Myer, Gregory D.
2013-01-01
Although the power clean test is routinely used to assess strength and power performance in adult athletes, the reliability of this measure in younger populations has not been examined. Therefore, the purpose of this study was to determine the reliability of the one repetition maximum (1 RM) power clean in adolescent athletes. Thirty-six male athletes (age 15.9 ± 1.1 yrs, body mass 79.1 ± 20.3 kg, height 175.1 ±7.4 cm) who had more than 1 year of training experience with weightlifting exercises performed a 1 RM power clean on two nonconsecutive days in the afternoon following standardized procedures. All test procedures were supervised by a senior level weightlifting coach and consisted of a systematic progression in test load until the maximum resistance that could be lifted for one repetition using proper exercise technique was determined. Data were analyzed using an intraclass correlation coefficient (ICC [2,k]), Pearson correlation coefficient (r), repeated measures ANOVA, Bland-Altman plot, and typical error analyses. Analysis of the data revealed that the test measures were highly reliable demonstrating a test-retest ICC of 0.98 (95% CI = 0.96–0.99). Testing also demonstrated a strong relationship between 1 RM measures on trial 1 and trial 2 (r=0.98, padolescent athletes when standardized testing procedures are followed and qualified instruction is present. PMID:22233786
Artificial Neural Network In Maximum Power Point Tracking Algorithm Of Photovoltaic Systems
Modestas Pikutis
2014-05-01
Full Text Available Scientists are looking for ways to improve the efficiency of solar cells all the time. The efficiency of solar cells which are available to the general public is up to 20%. Part of the solar energy is unused and a capacity of solar power plant is significantly reduced – if slow controller or controller which cannot stay at maximum power point of solar modules is used. Various algorithms of maximum power point tracking were created, but mostly algorithms are slow or make mistakes. In the literature more and more oftenartificial neural networks (ANN in maximum power point tracking process are mentioned, in order to improve performance of the controller. Self-learner artificial neural network and IncCond algorithm were used for maximum power point tracking in created solar power plant model. The algorithm for control was created. Solar power plant model is implemented in Matlab/Simulink environment.
Miyaguchi, Kazuyoshi; Demura, Shinichi
2008-11-01
This study aimed to examine the relationships between muscle power output using the stretch-shortening cycle (SSC) and eccentric maximum strength under elbow flexion. Eighteen young adult males pulled up a constant light load (2 kg) by ballistic elbow flexion under the following two preliminary conditions: 1) the static relaxed muscle state (SR condition), and 2) using the SSC with countermovement (SSC condition).Muscle power was determined from the product of the pulling velocity and the load mass by a power measurement instrument that adopted the weight-loading method. We assumed the pulling velocity to be the subject's muscle power parameters as a matter of convenience, because we used a constant load. The following two parameters were selected in reference to a previous study: 1) peak velocity (m x s(-1)) (peak power) and 2) 0.1-second velocity during concentric contraction (m x s(-1)) (initial power). Eccentric maximum strength by elbow flexion was measured by a handheld dynamometer.Initial power produced in the SSC condition was significantly larger than that in the SR condition. Eccentric maximum strength showed a significant and high correlation (r = 0.70) with peak power in the SSC condition but not in the SR condition. Eccentric maximum strength showed insignificant correlations with initial power in both conditions. In conclusion, it was suggested that eccentric maximum strength is associated with peak power in the SSC condition, but the contribution of the eccentric maximum strength to the SSC potentiation (initial power) may be low.
Thermoelectric Power Generator Design for Maximum Power: It's All About ZT
McCarty, R.
2013-07-01
There is a significant amount of literature that discusses thermoelectric power generator (TEG) design, but much of it overly simplifies the design space and therefore the results have limited use in designing real-life systems. This paper develops a more comprehensive model of the thermal and electrical interactions of a TEG in a system with known hot-side and cold-side thermal resistances and corresponding constant system temperature differential. Two design scenarios are investigated for common TEG system applications. In one method, the power from a TEG is maximized for a given electrical load, simulating a case where the TEG is electrically in series with a known load such as a fan. In the second design scenario, the power from a TEG is maximized for a given electrical load resistance ratio, n (the ratio between the external load resistance and the internal TEG resistance), simulating an application where the TEG is electrically in series with a load-matching converter. An interesting conclusion from this work is that, in the first design scenario, the electrical load resistance ratio, n, that maximizes TEG power occurs at √{1 + ZT} (where ZT is the thermoelectric figure of merit) instead of 1 as reported previously in literature. Equally interesting is that, if you define an analogous thermal resistance ratio, m' (representing the ratio between the TEG thermal resistance at open-circuit conditions and the system thermal resistance), the maximum power in both design scenarios occurs at √{1 + ZT} instead of the commonly cited value of 1. Furthermore, results are presented for real-life designs that incorporate electrical and thermal losses common to realistic TEG systems such as electrical contact resistance and thermal bypass around the TEG due to sealing.
Global Maximum Power Point Tracking of Photovoltaic Array under Partial Shaded Conditions
G.Shobana, P. Sornadeepika, Dr. R. Ramaprabha
2013-07-01
Full Text Available Efficiency of the PV module can be improved by operating at its peak power point so that the maximum power can be delivered to the load under varying environmental conditions. This paper is mainly focused on the maximum power point tracking of solar photovoltaic array (PV under non uniform insolation conditions. A maximum power point tracker (MPPT is used for extracting the maximum power from the solar PV module and transferring that power to the load. The problem of maximum power point (MPP tracking becomes a problem when the array receives non uniform insolation. Cells under shade absorb a large amount of electric power generated by cells receiving high insolation and convert it into heat which may damage the low illuminated cells. To relieve the stress on shaded cells, bypass diodes are added across the modules. In such a case multiple peaks in voltagepower characteristics are observed. Classical MPPT methods are not effective due to their inability to discriminate between local and global maximum. In this paper, Global MPPT algorithm is proposed to track the global maximum power point of PV array under partial shaded conditions.
Norhisam Misron
2016-08-01
Full Text Available A new control estimator to maximize the power generated with a maximum power point estimator is introduced. The power mapping characteristics from the double-stator generator are modeled as a mathematical equation which is used to develop the estimator for maximum power tracking to maximize the generated power. The proposed estimator automatically traces the instantaneous maximum power at various load conditions. However, to stabilize the output voltage, a boost converter is used from the inverter side. The developed double-stator generator is tested with the new estimator for the maximizing power generation capability under laboratory conditions. The experimental results confirm that with the new estimator, the average power generation capability is increased by 12% and the peak value is increase by 22%.
Individual Module Maximum Power Point Tracking for a Thermoelectric Generator Systems
Vadstrup, Casper; Chen, Min; Schaltz, Erik
Thermo Electric Generator (TEG) modules are often connected in a series and/or parallel system in order to match the TEG system voltage with the load voltage. However, in order to be able to control the power production of the TEG system a DC/DC converter is inserted between the TEG system...... and the load. The DC/DC converter is under the control of a Maximum Power Point Tracker (MPPT) which insures that the TEG system produces the maximum possible power to the load. However, if the conditions, e.g. temperature, health, etc., of the TEG modules are different each TEG module will not produce its...... maximum power. The result of the system MPPT is therefore the best compromise of all the TEG modules in the system. On the other hand, if each TEG module is controlled individual, each TEG module can be operated in its maximum power point and the TEG system output power will therefore be higher...
Westhoff, M.; Erpicum, S.; Archambeau, P.; Pirotton, M.; Zehe, E.; Dewals, B.
2015-12-01
Power can be performed by a system driven by a potential difference. From a given potential difference, the power that can be subtracted is constraint by the Carnot limit, which follows from the first and second laws of thermodynamics. If the system is such that the flux producing power (with power being the flux times its driving potential difference) also influences the potential difference, a maximum in power can be obtained as a result of the trade-off between the flux and the potential difference. This is referred to as the maximum power principle. It has already been shown that the atmosphere operates close to this maximum power limit when it comes to heat transport from the Equator to the poles, or vertically, from the surface to the atmospheric boundary layer. To reach this state of maximum power, the effective thermal conductivity of the atmosphere is adapted by the creation of convection cells. The aim of this study is to test if the soil's effective hydraulic conductivity also adapts in such a way that it produces maximum power. However, the soil's hydraulic conductivity adapts differently; for example by the creation of preferential flow paths. Here, this process is simulated in a lab experiment, which focuses on preferential flow paths created by piping. In the lab, we created a hydrological analogue to the atmospheric model dealing with heat transport between Equator and poles, with the aim to test if the effective hydraulic conductivity of the sand bed can be predicted with the maximum power principle. The experimental setup consists of two freely draining reservoir connected with each other by a confined aquifer. By adding water to only one reservoir, a potential difference will build up until a steady state is reached. The results will indicate whether the maximum power principle does apply for groundwater flow and how it should be applied. Because of the different way of adaptation of flow conductivity, the results differ from that of the
Mohsen Taherbaneh
2010-01-01
Full Text Available In applications with low-energy conversion efficiency, maximizing the output power improves the efficiency. The maximum output power of a solar panel depends on the environmental conditions and load profile. In this paper, a method based on simultaneous use of two fuzzy controllers is developed in order to maximize the generated output power of a solar panel in a photovoltaic system: fuzzy-based sun tracking and maximum power point tracking. The sun tracking is performed by changing the solar panel orientation in horizontal and vertical directions by two DC motors properly designed. A DC-DC converter is employed to track the solar panel maximum power point. In addition, the proposed system has the capability of the extraction of solar panel I-V curves. Experimental results present that the proposed fuzzy techniques result in increasing of power delivery from the solar panel, causing a reduction in size, weight, and cost of solar panels in photovoltaic systems.
Maximum Power Game as a Physical and Social Extension of Classical Games
Kim, Pilwon
2017-01-01
We consider an electric circuit in which the players participate as resistors and adjust their resistance in pursuit of individual maximum power. The maximum power game(MPG) becomes very complicated in a circuit which is indecomposable into serial/parallel components, yielding a nontrivial power distribution at equilibrium. Depending on the circuit topology, MPG covers a wide range of phenomena: from a social dilemma in which the whole group loses to a well-coordinated situation in which the individual pursuit of power promotes the collective outcomes. We also investigate a situation where each player in the circuit has an intrinsic heat waste. Interestingly, it is this individual inefficiency which can keep them from the collective failure in power generation. When coping with an efficient opponent with small intrinsic resistance, a rather inefficient player gets more power than efficient one. A circuit with multiple voltage inputs forms the network-based maximum power game. One of our major interests is to figure out, in what kind of the networks the pursuit for private power leads to greater total power. It turns out that the circuits with the scale-free structure is one of the good candidates which generates as much power as close to the possible maximum total. PMID:28272544
Maximum Power Game as a Physical and Social Extension of Classical Games
Kim, Pilwon
2017-03-01
We consider an electric circuit in which the players participate as resistors and adjust their resistance in pursuit of individual maximum power. The maximum power game(MPG) becomes very complicated in a circuit which is indecomposable into serial/parallel components, yielding a nontrivial power distribution at equilibrium. Depending on the circuit topology, MPG covers a wide range of phenomena: from a social dilemma in which the whole group loses to a well-coordinated situation in which the individual pursuit of power promotes the collective outcomes. We also investigate a situation where each player in the circuit has an intrinsic heat waste. Interestingly, it is this individual inefficiency which can keep them from the collective failure in power generation. When coping with an efficient opponent with small intrinsic resistance, a rather inefficient player gets more power than efficient one. A circuit with multiple voltage inputs forms the network-based maximum power game. One of our major interests is to figure out, in what kind of the networks the pursuit for private power leads to greater total power. It turns out that the circuits with the scale-free structure is one of the good candidates which generates as much power as close to the possible maximum total.
Recent advance on the efficiency at maximum power of heat engines
Tu Zhan-Chun
2012-01-01
This review reports several key advances on the theoretical investigations of efficiency at maximum power of heat engines in the past five years.The analytical results of efficiency at maximum power for the Curzon-Ahlborn heat engine,the stochastic heat engine constructed from a Brownian particle,and Feynman's ratchet as a heat engine are presented.It is found that:the efficiency at maximum power exhibits universal behavior at small relative temperature differences; the lower and the upper bounds might exist under quite general conditions; and the problem of efficiency at maximum power comes down to seeking for the minimum irreversible entropy production in each finite-time isothermal process for a given time.
Maximum Power Point Tracking of Photovoltaic System for Traffic Light Application
Riza Muhida
2013-07-01
Full Text Available Photovoltaic traffic light system is a significant application of renewable energy source. The development of the system is an alternative effort of local authority to reduce expenditure for paying fees to power supplier which the power comes from conventional energy source. Since photovoltaic (PV modules still have relatively low conversion efficiency, an alternative control of maximum power point tracking (MPPT method is applied to the traffic light system. MPPT is intended to catch up the maximum power at daytime in order to charge the battery at the maximum rate in which the power from the battery is intended to be used at night time or cloudy day. MPPT is actually a DC-DC converter that can step up or down voltage in order to achieve the maximum power using Pulse Width Modulation (PWM control. From experiment, we obtained the voltage of operation using MPPT is at 16.454 V, this value has error of 2.6%, if we compared with maximum power point voltage of PV module that is 16.9 V. Based on this result it can be said that this MPPT control works successfully to deliver the power from PV module to battery maximally.
40 CFR 141.11 - Maximum contaminant levels for inorganic chemicals.
2010-07-01
... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Maximum contaminant levels for inorganic chemicals. 141.11 Section 141.11 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Maximum Contaminant Levels § 141.11 Maximum contaminant levels...
Improved Reliability of Single-Phase PV Inverters by Limiting the Maximum Feed-in Power
Yang, Yongheng; Wang, Huai; Blaabjerg, Frede
2014-01-01
. The CPG control strategy is activated only when the DC input power from PV panels exceeds a specific power limit. It enables to limit the maximum feed-in power to the electric grids and also to improve the utilization of PV inverters. As a further study, this paper investigates the reliability performance...... of the power devices (e.g. IGBTs) used in PV inverters with the CPG control under different feed-in power limits. A long-term mission profile (i.e. solar irradiance and ambient temperature) based stress analysis approach is extended and applied to obtain the yearly electrical and thermal stresses of the power...
Extension Sliding Mode Controller for Maximum Power Point Tracking of Hydrogen Fuel Cells
Meng-Hui Wang
2013-01-01
Full Text Available Fuel cells (FCs are characterized by low pollution, low noise, and high efficiency. However, the voltage-current response of an FC is nonlinear, with the result that there exists just one operating point which maximizes the output power given a particular set of operating conditions. Accordingly, the present study proposes a maximum power point tracking (MPPT control scheme based on extension theory to stabilize the output of an FC at the point of maximum power. The simulation results confirm the ability of the controller to stabilize the output power at the maximum power point despite sudden changes in the temperature, hydrogen pressure, and membrane water content. Moreover, the transient response time of the proposed controller is shown to be faster than that of existing sliding mode (SM and extremum seeking (ES controllers.
Sclocchi, M.
2010-07-01
This article analyzes the problem of lost socks in the production of electricity caused by partial shading of a photovoltaic system. introducing the advantages of distributed maximum power point tracking system, MPPT the level of the panel and is the outcome of real cases with different technology Solar Magic. (Author)
L. M. Miller
2010-09-01
Full Text Available The availability of wind power for renewable energy extraction is ultimately limited by how much kinetic energy is generated by natural processes within the Earth system and by fundamental limits of how much of the wind power can be extracted. Here we use these considerations to provide a maximum estimate of wind power availability over land. We use three different methods. First, we use simple, established estimates of the energetics of the atmospheric circulation, which yield about 38 TW of wind power available for extraction. Second, we set up a simple momentum balance model to estimate maximum extractability which we then apply to reanalysis climate data, yielding an estimate of 17 TW. Finally, we perform climate model simulations in which we extract different amounts of momentum from the atmospheric boundary layer to obtain a maximum estimate of how much power can be extracted, yielding 36 TW. These three methods consistently yield maximum estimates in the range of 17–38 TW and are notably less than recent estimates that claim abundant wind power availability. Furthermore, we show with the climate model simulations that the climatic effects at maximum wind power extraction are similar in magnitude to those associated with a doubling of atmospheric CO_{2}. We conclude that in order to understand fundamental limits to renewable energy resources, as well as the impacts of their utilization, it is imperative to use a thermodynamic, Earth system perspective, rather than engineering specifications of the latest technology.
MODEL PREDICTIVE CONTROL FOR PHOTOVOLTAIC STATION MAXIMUM POWER POINT TRACKING SYSTEM
I. Elzein
2015-01-01
Full Text Available The purpose of this paper is to present an alternative maximum power point tracking, MPPT, algorithm for a photovoltaic module, PVM, to produce the maximum power, Pmax, using the optimal duty ratio, D, for different types of converters and load matching.We present a state-based approach to the design of the maximum power point tracker for a stand-alone photovoltaic power generation system. The system under consideration consists of a solar array with nonlinear time-varying characteristics, a step-up converter with appropriate filter.The proposed algorithm has the advantages of maximizing the efficiency of the power utilization, can be integrated to other MPPT algorithms without affecting the PVM performance, is excellent for Real-Time applications and is a robust analytical method, different from the traditional MPPT algorithms which are more based on trial and error, or comparisons between present and past states. The procedure to calculate the optimal duty ratio for a buck, boost and buck-boost converters, to transfer the maximum power from a PVM to a load, is presented in the paper. Additionally, the existence and uniqueness of optimal internal impedance, to transfer the maximum power from a photovoltaic module using load matching, is proved.
A thermoelectric generator using loop heat pipe and design match for maximum-power generation
Huang, Bin-Juine
2015-09-05
The present study focuses on the thermoelectric generator (TEG) using loop heat pipe (LHP) and design match for maximum-power generation. The TEG uses loop heat pipe, a passive cooling device, to dissipate heat without consuming power and free of noise. The experiments for a TEG with 4W rated power show that the LHP performs very well with overall thermal resistance 0.35 K W-1, from the cold side of TEG module to the ambient. The LHP is able to dissipate heat up to 110W and is maintenance free. The TEG design match for maximum-power generation, called “near maximum-power point operation (nMPPO)”, is studied to eliminate the MPPT (maximum-power point tracking controller). nMPPO is simply a system design which properly matches the output voltage of TEG with the battery. It is experimentally shown that TEG using design match for maximum-power generation (nMPPO) performs better than TEG with MPPT.
40 CFR 141.62 - Maximum contaminant levels for inorganic contaminants.
2010-07-01
... (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS National Primary Drinking Water Regulations: Maximum Contaminant Levels and Maximum Residual Disinfectant Levels § 141.62 Maximum..., maintenance, and monitoring must be provided by the water system to ensure adequate performance. 5 Unlikely to...
Control of Hybrid System Using Multi-Input Inverter and Maximum Power Point Tracking
N.Sivakumar
2013-07-01
Full Text Available The objective of this paper is to control the Wind/PV hybrid system using Multi-input inverter to get constant output power for different operating conditions. The MPPT also used in this system to get the maximum peak power to the load. The perturbation observation (P&O method is used to accomplish the maximum power point tracking algorithm for input sources. The operating principle of the open loop and closed loop circuit of multi-input inverter is discussed.
A Hybrid Maximum Power Point Tracking Method for Automobile Exhaust Thermoelectric Generator
Quan, Rui; Zhou, Wei; Yang, Guangyou; Quan, Shuhai
2016-08-01
To make full use of the maximum output power of automobile exhaust thermoelectric generator (AETEG) based on Bi2Te3 thermoelectric modules (TEMs), taking into account the advantages and disadvantages of existing maximum power point tracking methods, and according to the output characteristics of TEMs, a hybrid maximum power point tracking method combining perturb and observe (P&O) algorithm, quadratic interpolation and constant voltage tracking method was put forward in this paper. Firstly, it searched the maximum power point with P&O algorithms and a quadratic interpolation method, then, it forced the AETEG to work at its maximum power point with constant voltage tracking. A synchronous buck converter and controller were implemented in the electric bus of the AETEG applied in a military sports utility vehicle, and the whole system was modeled and simulated with a MATLAB/Simulink environment. Simulation results demonstrate that the maximum output power of the AETEG based on the proposed hybrid method is increased by about 3.0% and 3.7% compared with that using only the P&O algorithm and the quadratic interpolation method, respectively. The shorter tracking time is only 1.4 s, which is reduced by half compared with that of the P&O algorithm and quadratic interpolation method, respectively. The experimental results demonstrate that the tracked maximum power is approximately equal to the real value using the proposed hybrid method,and it can preferentially deal with the voltage fluctuation of the AETEG with only P&O algorithm, and resolve the issue that its working point can barely be adjusted only with constant voltage tracking when the operation conditions change.
A Hybrid Maximum Power Point Tracking Method for Automobile Exhaust Thermoelectric Generator
Quan, Rui; Zhou, Wei; Yang, Guangyou; Quan, Shuhai
2017-05-01
To make full use of the maximum output power of automobile exhaust thermoelectric generator (AETEG) based on Bi2Te3 thermoelectric modules (TEMs), taking into account the advantages and disadvantages of existing maximum power point tracking methods, and according to the output characteristics of TEMs, a hybrid maximum power point tracking method combining perturb and observe (P&O) algorithm, quadratic interpolation and constant voltage tracking method was put forward in this paper. Firstly, it searched the maximum power point with P&O algorithms and a quadratic interpolation method, then, it forced the AETEG to work at its maximum power point with constant voltage tracking. A synchronous buck converter and controller were implemented in the electric bus of the AETEG applied in a military sports utility vehicle, and the whole system was modeled and simulated with a MATLAB/Simulink environment. Simulation results demonstrate that the maximum output power of the AETEG based on the proposed hybrid method is increased by about 3.0% and 3.7% compared with that using only the P&O algorithm and the quadratic interpolation method, respectively. The shorter tracking time is only 1.4 s, which is reduced by half compared with that of the P&O algorithm and quadratic interpolation method, respectively. The experimental results demonstrate that the tracked maximum power is approximately equal to the real value using the proposed hybrid method,and it can preferentially deal with the voltage fluctuation of the AETEG with only P&O algorithm, and resolve the issue that its working point can barely be adjusted only with constant voltage tracking when the operation conditions change.
Tracking the global maximum power point of PV arrays under partial shading conditions
Fennich, Meryem
This thesis presents the theoretical and simulation studies of the global maximum power point tracking (MPPT) for photovoltaic systems under partial shading. The main goal is to track the maximum power point of the photovoltaic module so that the maximum possible power can be extracted from the photovoltaic panels. When several panels are connected in series with some of them shaded partially either due to clouds or shadows from neighboring buildings, several local maxima appear in the power vs. voltage curve. A power increment based MPPT algorithm is effective in identifying the global maximum from the several local maxima. Several existing MPPT algorithms are explored and the state-of-the-art power increment method is simulated and tested for various partial shading conditions. The current-voltage and power-voltage characteristics of the PV model are studied under different partial shading conditions, along with five different cases demonstrating how the MPPT algorithm performs when shading switches from one state to another. Each case is supplemented with simulation results. The method of tracking the Global MPP is based on controlling the DC-DC converter connected to the output of the PV array. A complete system simulation including the PV array, the direct current to direct current (DC-DC) converter and the MPPT is presented and tested using MATLAB software. The simulation results show that the MPPT algorithm works very well with the buck converter, while the boost converter needs further changes and implementation.
L. M. Miller
2011-02-01
Full Text Available The availability of wind power for renewable energy extraction is ultimately limited by how much kinetic energy is generated by natural processes within the Earth system and by fundamental limits of how much of the wind power can be extracted. Here we use these considerations to provide a maximum estimate of wind power availability over land. We use several different methods. First, we outline the processes associated with wind power generation and extraction with a simple power transfer hierarchy based on the assumption that available wind power will not geographically vary with increased extraction for an estimate of 68 TW. Second, we set up a simple momentum balance model to estimate maximum extractability which we then apply to reanalysis climate data, yielding an estimate of 21 TW. Third, we perform general circulation model simulations in which we extract different amounts of momentum from the atmospheric boundary layer to obtain a maximum estimate of how much power can be extracted, yielding 18–34 TW. These three methods consistently yield maximum estimates in the range of 18–68 TW and are notably less than recent estimates that claim abundant wind power availability. Furthermore, we show with the general circulation model simulations that some climatic effects at maximum wind power extraction are similar in magnitude to those associated with a doubling of atmospheric CO_{2}. We conclude that in order to understand fundamental limits to renewable energy resources, as well as the impacts of their utilization, it is imperative to use a "top-down" thermodynamic Earth system perspective, rather than the more common "bottom-up" engineering approach.
Mazza, Gina L; Enders, Craig K; Ruehlman, Linda S
2015-01-01
Often when participants have missing scores on one or more of the items comprising a scale, researchers compute prorated scale scores by averaging the available items. Methodologists have cautioned that proration may make strict assumptions about the mean and covariance structures of the items comprising the scale (Schafer & Graham, 2002 ; Graham, 2009 ; Enders, 2010 ). We investigated proration empirically and found that it resulted in bias even under a missing completely at random (MCAR) mechanism. To encourage researchers to forgo proration, we describe a full information maximum likelihood (FIML) approach to item-level missing data handling that mitigates the loss in power due to missing scale scores and utilizes the available item-level data without altering the substantive analysis. Specifically, we propose treating the scale score as missing whenever one or more of the items are missing and incorporating items as auxiliary variables. Our simulations suggest that item-level missing data handling drastically increases power relative to scale-level missing data handling. These results have important practical implications, especially when recruiting more participants is prohibitively difficult or expensive. Finally, we illustrate the proposed method with data from an online chronic pain management program.
Overview of Maximum Power Point Tracking Techniques for Photovoltaic Energy Production Systems
Koutroulis, Eftichios; Blaabjerg, Frede
2015-01-01
of photovoltaic sources during stochastically varying solar irradiation and ambient temperature conditions. Thus, the overall efficiency of the photovoltaic energy production system is increased. Numerous techniques have been presented during the last decade for implementing the maximum power point tracking......A substantial growth of the installed photovoltaic systems capacity has occurred around the world during the last decade, thus enhancing the availability of electric energy in an environmentally friendly way. The maximum power point tracking technique enables maximization of the energy production...... process in a photovoltaic system. This article provides an overview of the operating principles of these techniques, which are suited for either uniform or non-uniform solar irradiation conditions. The operational characteristics and implementation requirements of these maximum power point tracking...
Azam Zaka
2014-10-01
Full Text Available This paper is concerned with the modifications of maximum likelihood, moments and percentile estimators of the two parameter Power function distribution. Sampling behavior of the estimators is indicated by Monte Carlo simulation. For some combinations of parameter values, some of the modified estimators appear better than the traditional maximum likelihood, moments and percentile estimators with respect to bias, mean square error and total deviation.
Efficiency at maximum power for an Otto engine with ideal feedback
Wang, Honghui; He, Jizhou; Wang, Jianhui; Wu, Zhaoqi
2016-10-01
We propose an Otto heat engine that undergoes processes involving a special class of feedback and analyze theoretically its response. We use stochastic thermodynamics to determine the performance characteristics of the heat engine and indicate the possibility that its maximum efficiency can surpass the Carnot value. The analytical expression for efficiency at maximum power, including the effects resulting from feedback, reduces to that previously derived based on an engine without feedback.
Power electronics and control techniques for maximum energy harvesting in photovoltaic systems
Femia, Nicola
2012-01-01
Incentives provided by European governments have resulted in the rapid growth of the photovoltaic (PV) market. Many PV modules are now commercially available, and there are a number of power electronic systems for processing the electrical power produced by PV systems, especially for grid-connected applications. Filling a gap in the literature, Power Electronics and Control Techniques for Maximum Energy Harvesting in Photovoltaic Systems brings together research on control circuits, systems, and techniques dedicated to the maximization of the electrical power produced by a photovoltaic (PV) so
Artificial Neural Network Maximum Power Point Tracker for Solar Electric Vehicle
Theodore Amissah OCRAN; CAO Junyi; CAO Binggang; SUN Xinghua
2005-01-01
This paper proposes an artificial neural network maximum power point tracker (MPPT) for solar electric vehicles. The MPPT is based on a highly efficient boost converter with insulated gate bipolar transistor (IGBT) power switch. The reference voltage for MPPT is obtained by artificial neural network (ANN) with gradient descent momentum algorithm. The tracking algorithm changes the duty-cycle of the converter so that the PV-module voltage equals the voltage corresponding to the MPPT at any given insolation, temperature, and load conditions. For fast response, the system is implemented using digital signal processor (DSP). The overall system stability is improved by including a proportional-integral-derivative (PID) controller, which is also used to match the reference and battery voltage levels. The controller, based on the information supplied by the ANN, generates the boost converter duty-cycle. The energy obtained is used to charge the lithium ion battery stack for the solar vehicle. The experimental and simulation results show that the proposed scheme is highly efficient.
40 CFR 142.61 - Variances from the maximum contaminant level for fluoride.
2010-07-01
... level for fluoride. 142.61 Section 142.61 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... from the maximum contaminant level for fluoride. (a) The Administrator, pursuant to section 1415(a)(1... means generally available for achieving compliance with the Maximum Contaminant Level for fluoride. (1...
Procedure for determining maximum sustainable power generated by microbial fuel cells.
Menicucci, Joseph; Beyenal, Haluk; Marsili, Enrico; Veluchamy, Raajaraajan Angathevar; Demir, Goksel; Lewandowski, Zbigniew
2006-02-01
Power generated by microbial fuel cells is computed as a product of current passing through an external resistor and voltage drop across this resistor. If the applied resistance is very low, then high instantaneous power generated by the cell is measured, which is not sustainable; the cell cannot deliver that much power for long periods of time. Since using small electrical resistors leads to erroneous assessment of the capabilities of microbial fuel cells, a question arises: what resistor should be used in such measurements? To address this question, we have defined the sustainable power as the steady state of power delivery by a microbial fuel cell under a given set of conditions and the maximum sustainable power as the highest sustainable power that a microbial fuel cell can deliver under a given set of conditions. Selecting the external resistance that is associated with the maximum sustainable power in a microbial fuel cell (MFC) is difficult because the operator has limited influence on the main factors that control power generation: the rate of charge transfer at the current-limiting electrode and the potential established across the fuel cell. The internal electrical resistance of microbial fuel cells varies, and it depends on the operational conditions of the fuel cell. We have designed an empirical procedure to predict the maximum sustainable power that can be generated by a microbial fuel cell operated under a given set of conditions. Following the procedure, we change the external resistors incrementally, in steps of 500 omega every 10, 60, or 180 s and measure the anode potential, the cathode potential, and the cell current. Power generated in the microbial fuel cell that we were using was limited by the anodic current. The anodic potential was used to determine the condition where the maximum sustainable power is obtained. The procedure is simple, microbial fuel cells can be characterized within an hour, and the results of the measurements can serve
Two-Stage Chaos Optimization Search Application in Maximum Power Point Tracking of PV Array
Lihua Wang
2014-01-01
Full Text Available In order to deliver the maximum available power to the load under the condition of varying solar irradiation and environment temperature, maximum power point tracking (MPPT technologies have been used widely in PV systems. Among all the MPPT schemes, the chaos method is one of the hot topics in recent years. In this paper, a novel two-stage chaos optimization method is presented which can make search faster and more effective. In the process of proposed chaos search, the improved logistic mapping with the better ergodic is used as the first carrier process. After finding the current optimal solution in a certain guarantee, the power function carrier as the secondary carrier process is used to reduce the search space of optimized variables and eventually find the maximum power point. Comparing with the traditional chaos search method, the proposed method can track the change quickly and accurately and also has better optimization results. The proposed method provides a new efficient way to track the maximum power point of PV array.
Maximum Power Point Tracking Method For PV Array Under Partially Shaded Condition
Belqasem Aljafari
2016-08-01
Full Text Available Solar radiation that hits the photovoltaic modules has a variable character depending on the position, the direction of the solar field, the season, and the hour of the day. During the trajectory of a day, a shadow may be decanted on the cell, which may be contemplated, as in the case of a building near the solar field, or unforeseeable as those created by clouds. The breakthrough of PV systems as distributed power generation systems has increased drastically in the last few years. Because of this Maximum Power Point Tracking (MPPT is becoming more and more substantial as the amount of energy generated by PV systems is increasing. A MPPT technique must be used to track the maximum power point since the MPP depends on solar irradiation and cell temperature. In general, when the impedances of the load and source are matched, the maximum power is transferred to the load from the source only. The generated energy from PV systems must be maximized, as the efficiency of solar panels is low. For that reason to get the maximum power, a PV system is repeatedly equipped with an MPP tracker. Several MPP pursuit techniques have been proposed and implemented in recent years
Realworld maximum power point tracking simulation of PV system based on Fuzzy Logic control
Othman, Ahmed M.; El-arini, Mahdi M. M.; Ghitas, Ahmed; Fathy, Ahmed
2012-12-01
In the recent years, the solar energy becomes one of the most important alternative sources of electric energy, so it is important to improve the efficiency and reliability of the photovoltaic (PV) systems. Maximum power point tracking (MPPT) plays an important role in photovoltaic power systems because it maximize the power output from a PV system for a given set of conditions, and therefore maximize their array efficiency. This paper presents a maximum power point tracker (MPPT) using Fuzzy Logic theory for a PV system. The work is focused on the well known Perturb and Observe (P&O) algorithm and is compared to a designed fuzzy logic controller (FLC). The simulation work dealing with MPPT controller; a DC/DC Ćuk converter feeding a load is achieved. The results showed that the proposed Fuzzy Logic MPPT in the PV system is valid.
Realworld maximum power point tracking simulation of PV system based on Fuzzy Logic control
Ahmed M. Othman
2012-12-01
Full Text Available In the recent years, the solar energy becomes one of the most important alternative sources of electric energy, so it is important to improve the efficiency and reliability of the photovoltaic (PV systems. Maximum power point tracking (MPPT plays an important role in photovoltaic power systems because it maximize the power output from a PV system for a given set of conditions, and therefore maximize their array efficiency. This paper presents a maximum power point tracker (MPPT using Fuzzy Logic theory for a PV system. The work is focused on the well known Perturb and Observe (P&O algorithm and is compared to a designed fuzzy logic controller (FLC. The simulation work dealing with MPPT controller; a DC/DC Ćuk converter feeding a load is achieved. The results showed that the proposed Fuzzy Logic MPPT in the PV system is valid.
SIMULATING MODEL OF SYSTEM FOR MAXIMUM OUTPUT POWER OF SOLAR BATTERY
Abdul Majid Al-Khatib
2005-01-01
Full Text Available Simulating model and algorithm for control of electric power converter of a solar battery are proposed in the paper. Control device of D.C. step-down converter with pulse-width modulation is designed on microprocessor basis. Simulating model permits to investigate various operational modes of a solar battery, demonstrates a process with maximum power mode and is characterized by convenient user’s interface.
Development of an Intelligent Maximum Power Point Tracker Using an Advanced PV System Test Platform
Spataru, Sergiu; Amoiridis, Anastasios; Beres, Remus Narcis
2013-01-01
The performance of photovoltaic systems is often reduced by the presence of partial shadows. The system efficiency and availability can be improved by a maximum power point tracking algorithm that is able to detect partial shadow conditions and to optimize the power output. This work proposes an ...... photovoltaic inverter system test platform that is able to reproduce realistic partial shadow conditions, both in simulation and on hardware test system....
Chalise, Santosh
Although solar photovoltaic (PV) systems have remained the fastest growing renewable power generating technology, variability as well as uncertainty in the output of PV plants is a significant issue. This rapid increase in PV grid-connected generation presents not only progress in clean energy but also challenges in integration with traditional electric power grids which were designed for transmission and distribution of power from central stations. Unlike conventional electric generators, PV panels do not have rotating parts and thus have no inertia. This potentially causes a problem when the solar irradiance incident upon a PV plant changes suddenly, for example, when scattered clouds pass quickly overhead. The output power of the PV plant may fluctuate nearly as rapidly as the incident irradiance. These rapid power output fluctuations may then cause voltage fluctuations, frequency fluctuations, and power quality issues. These power quality issues are more severe with increasing PV plant power output. This limits the maximum power output allowed from interconnected PV plants. Voltage regulation of a distribution system, a focus of this research, is a prime limiting factor in PV penetration levels. The IEEE 13-node test feeder, modeled and tested in the MATLAB/Simulink environment, was used as an example distribution feeder to analyze the maximum acceptable penetration of a PV plant. The effect of the PV plant's location was investigated, along with the addition of a VAR compensating device (a D-STATCOM in this case). The results were used to develop simple guidelines for determining an initial estimate of the maximum PV penetration level on a distribution feeder. For example, when no compensating devices are added to the system, a higher level of PV penetration is generally achieved by installing the PV plant close to the substation. The opposite is true when a VAR compensator is installed with the PV plant. In these cases, PV penetration levels over 50% may be
Analytical expressions for maximum wind turbine average power in a Rayleigh wind regime
Carlin, P.W.
1996-12-01
Average or expectation values for annual power of a wind turbine in a Rayleigh wind regime are calculated and plotted as a function of cut-out wind speed. This wind speed is expressed in multiples of the annual average wind speed at the turbine installation site. To provide a common basis for comparison of all real and imagined turbines, the Rayleigh-Betz wind machine is postulated. This machine is an ideal wind machine operating with the ideal Betz power coefficient of 0.593 in a Rayleigh probability wind regime. All other average annual powers are expressed in fractions of that power. Cases considered include: (1) an ideal machine with finite power and finite cutout speed, (2) real machines operating in variable speed mode at their maximum power coefficient, and (3) real machines operating at constant speed.
Maximum power point tracking for photovoltaic system using model predictive control
Ma, Chao; Li, Ning; Li, Shaoyuan [Shanghai Jiao Tong Univ., Shanghai (China). Key Lab. of System Control and Information Processing
2013-07-01
In this paper, T-G-P model is built to find maximum power point according to light intensity and temperature, making it easier and more clearly for photovoltaic system to track the MPP. A predictive controller considering constraints for safe operation is designed. The simulation results show that the system can track MPP quickly, accurately and effectively.
Fang, W.; Quan, S. H.; Xie, C. J.; Tang, X. F.; Wang, L. L.; Huang, L.
2016-03-01
In this study, a direct-current/direct-current (DC/DC) converter with maximum power point tracking (MPPT) is developed to down-convert the high voltage DC output from a thermoelectric generator to the lower voltage required to charge batteries. To improve the tracking accuracy and speed of the converter, a novel MPPT control scheme characterized by an aggregated dichotomy and gradient (ADG) method is proposed. In the first stage, the dichotomy algorithm is used as a fast search method to find the approximate region of the maximum power point. The gradient method is then applied for rapid and accurate tracking of the maximum power point. To validate the proposed MPPT method, a test bench composed of an automobile exhaust thermoelectric generator was constructed for harvesting the automotive exhaust heat energy. Steady-state and transient tracking experiments under five different load conditions were carried out using a DC/DC converter with the proposed ADG and with three traditional methods. The experimental results show that the ADG method can track the maximum power within 140 ms with a 1.1% error rate when the engine operates at 3300 rpm@71 NM, which is superior to the performance of the single dichotomy method, the single gradient method and the perturbation and observation method from the viewpoint of improved tracking accuracy and speed.
Review of the maximum power point tracking algorithms for stand-alone photovoltaic systems
Salas, V.; Olias, E.; Barrado, A.; Lazaro, A. [Departamento de Tecnologia Electronica/Grupo de Sistemas Electronicos de Potencia, Universidad Carlos III de Madrid, Avda. de la Universidad, 30-28911 Leganes, Madrid (Spain)
2006-07-06
A survey of the algorithms for seeking the maximum power point (MPP) is proposed. As has been shown, there are many ways of distinguishing and grouping methods that seek the MPP from a photovoltaic (PV) generator. However, in this article they are grouped as either direct or nondirect methods. The indirect methods ('quasi seeks') have the particular feature that the MPP is estimated from the measures of the PV generator's voltage and current PV, the irradiance, or using empiric data, by mathematical expressions of numerical approximations. Therefore, the estimation is carried out for a specific PV generator installed in the system. Thus, they do not obtain the maximum power for any irradiance or temperature and none of them are able to obtain the MPP exactly. Subsequently, they are known as 'quasi seeks'. Nevertheless, the direct methods ('true seeking methods') can also be distinguished. They offer the advantage that they obtain the actual maximum power from the measures of the PV generator's voltage and current PV. In that case, they are suitable for any irradiance and temperature. All algorithms, direct and indirect, can be included in some of the DC/DC converters, Maximum power point trackings (MPPTs), for the stand-alone systems. (author)
Wu, Feilong; He, Jizhou; Ma, Yongli; Wang, Jianhui
2014-12-01
We consider the efficiency at maximum power of a quantum Otto engine, which uses a spin or a harmonic system as its working substance and works between two heat reservoirs at constant temperatures Th and Tc (Otto engine working in the linear-response regime.
A Digital Coreless Maximum Power Point Tracking Circuit for Thermoelectric Generators
Kim, Shiho; Cho, Sungkyu; Kim, Namjae; Baatar, Nyambayar; Kwon, Jangwoo
2011-05-01
This paper describes a maximum power point tracking (MPPT) circuit for thermoelectric generators (TEG) without a digital controller unit. The proposed method uses an analog tracking circuit that samples the half point of the open-circuit voltage without a digital signal processor (DSP) or microcontroller unit for calculating the peak power point using iterative methods. The simulation results revealed that the MPPT circuit, which employs a boost-cascaded-with-buck converter, handled rapid variation of temperature and abrupt changes of load current; this method enables stable operation with high power transfer efficiency. The proposed MPPT technique is a useful analog MPPT solution for thermoelectric generators.
Efficiency at and near maximum power of low-dissipation heat engines.
Holubec, Viktor; Ryabov, Artem
2015-11-01
A universality in optimization of trade-off between power and efficiency for low-dissipation Carnot cycles is presented. It is shown that any trade-off measure expressible in terms of efficiency and the ratio of power to its maximum value can be optimized independently of most details of the dynamics and of the coupling to thermal reservoirs. The result is demonstrated on two specific trade-off measures. The first one is designed for finding optimal efficiency for a given output power and clearly reveals diseconomy of engines working at maximum power. As the second example we derive universal lower and upper bounds on the efficiency at maximum trade-off given by the product of power and efficiency. The results are illustrated on a model of a diffusion-based heat engine. Such engines operate in the low-dissipation regime given that the used driving minimizes the work dissipated during the isothermal branches. The peculiarities of the corresponding optimization procedure are reviewed and thoroughly discussed.
Efficiency at and near maximum power of low-dissipation heat engines
Holubec, Viktor; Ryabov, Artem
2015-11-01
A universality in optimization of trade-off between power and efficiency for low-dissipation Carnot cycles is presented. It is shown that any trade-off measure expressible in terms of efficiency and the ratio of power to its maximum value can be optimized independently of most details of the dynamics and of the coupling to thermal reservoirs. The result is demonstrated on two specific trade-off measures. The first one is designed for finding optimal efficiency for a given output power and clearly reveals diseconomy of engines working at maximum power. As the second example we derive universal lower and upper bounds on the efficiency at maximum trade-off given by the product of power and efficiency. The results are illustrated on a model of a diffusion-based heat engine. Such engines operate in the low-dissipation regime given that the used driving minimizes the work dissipated during the isothermal branches. The peculiarities of the corresponding optimization procedure are reviewed and thoroughly discussed.
Alaraj, Muhannad; Radenkovic, Miloje; Park, Jae-Do
2017-02-01
Microbial fuel cells (MFCs) are renewable and sustainable energy sources that can be used for various applications. The MFC output power depends on its biochemical conditions as well as the terminal operating points in terms of output voltage and current. There exists one operating point that gives the maximum possible power from the MFC, maximum power point (MPP), for a given operating condition. However, this MPP may vary and needs to be tracked in order to maintain the maximum power extraction from the MFC. Furthermore, MFC reactors often develop voltage overshoots that cause drastic drops in the terminal voltage, current, and the output power. When the voltage overshoot happens, an additional control measure is necessary as conventional MPPT algorithms will fail because of the change in the voltage-current relationship. In this paper, the extremum seeking (ES) algorithm was used to track the varying MPP and a voltage overshoot avoidance (VOA) algorithm is developed to manage the voltage overshoot conditions. The proposed ES-MPPT with VOA algorithm was able to extract 197.2 mJ during 10-min operation avoiding voltage overshoot, while the ES MPPT-only scheme stopped harvesting after only 18.75 mJ because of the voltage overshoot happened at 0.4 min.
DURUSU, A.
2014-08-01
Full Text Available Maximum power point trackers (MPPTs play an essential role in extracting power from photovoltaic (PV panels as they make the solar panels to operate at the maximum power point (MPP whatever the changes of environmental conditions are. For this reason, they take an important place in the increase of PV system efficiency. MPPTs are driven by MPPT algorithms and a number of MPPT algorithms are proposed in the literature. The comparison of the MPPT algorithms in literature are made by a sun simulator based test system under laboratory conditions for short durations. However, in this study, the performances of four most commonly used MPPT algorithms are compared under real environmental conditions for longer periods. A dual identical experimental setup is designed to make a comparison between two the considered MPPT algorithms as synchronized. As a result of this study, the ranking among these algorithms are presented and the results show that Incremental Conductance (IC algorithm gives the best performance.
An improved maximum power point tracking method for a photovoltaic system
Ouoba, David; Fakkar, Abderrahim; El Kouari, Youssef; Dkhichi, Fayrouz; Oukarfi, Benyounes
2016-06-01
In this paper, an improved auto-scaling variable step-size Maximum Power Point Tracking (MPPT) method for photovoltaic (PV) system was proposed. To achieve simultaneously a fast dynamic response and stable steady-state power, a first improvement was made on the step-size scaling function of the duty cycle that controls the converter. An algorithm was secondly proposed to address wrong decision that may be made at an abrupt change of the irradiation. The proposed auto-scaling variable step-size approach was compared to some various other approaches from the literature such as: classical fixed step-size, variable step-size and a recent auto-scaling variable step-size maximum power point tracking approaches. The simulation results obtained by MATLAB/SIMULINK were given and discussed for validation.
Woonki Na
2017-03-01
Full Text Available This paper presents an improved maximum power point tracking (MPPT algorithm using a fuzzy logic controller (FLC in order to extract potential maximum power from photovoltaic cells. The objectives of the proposed algorithm are to improve the tracking speed, and to simultaneously solve the inherent drawbacks such as slow tracking in the conventional perturb and observe (P and O algorithm. The performances of the conventional P and O algorithm and the proposed algorithm are compared by using MATLAB/Simulink in terms of the tracking speed and steady-state oscillations. Additionally, both algorithms were experimentally validated through a digital signal processor (DSP-based controlled-boost DC-DC converter. The experimental results show that the proposed algorithm performs with a shorter tracking time, smaller output power oscillation, and higher efficiency, compared with the conventional P and O algorithm.
Recent Developments in Maximum Power Point Tracking Technologies for Photovoltaic Systems
Nevzat Onat
2010-01-01
Full Text Available In photovoltaic (PV system applications, it is very important to design a system for operating of the solar cells (SCs under best conditions and highest efficiency. Maximum power point (MPP varies depending on the angle of sunlight on the surface of the panel and cell temperature. Hence, the operating point of the load is not always MPP of PV system. Therefore, in order to supply reliable energy to the load, PV systems are designed to include more than the required number of modules. The solution to this problem is that switching power converters are used, that is called maximum power point tracker (MPPT. In this study, the various aspects of these algorithms have been analyzed in detail. Classifications, definitions, and basic equations of the most widely used MPPT technologies are given. Moreover, a comparison was made in the conclusion.
Low-Power Maximum a Posteriori (MAP Algorithm for WiMAX Convolutional Turbo Decoder
Chitralekha Ngangbam
2013-05-01
Full Text Available We propose to design a Low-Power Memory-Reduced Traceback MAP iterative decoding of convolutional turbo code (CTC which has large data access with large memories consumption and verify the functionality by using simulation tool. The traceback maximum a posteriori algorithm (MAP decoding provides the best performance in terms of bit error rate (BER and reduce the power consumption of the state metric cache (SMC without losing the correction performance. The computation and accessing of different metrics reduce the size of the SMC with no requires complicated reversion checker, path selection, and reversion flag cache. Radix-2*2 and radix-4 traceback structures provide a tradeoff between power consumption and operating frequency for double-binary (DB MAP decoding. These two traceback structures achieve an around 25% power reduction of the SMC, and around 12% power reduction of the DB MAP decoders for WiMAX standard
Design of Asymmetrical Relay Resonators for Maximum Efficiency of Wireless Power Transfer
Bo-Hee Choi
2016-01-01
Full Text Available This paper presents a new design method of asymmetrical relay resonators for maximum wireless power transfer. A new design method for relay resonators is demanded because maximum power transfer efficiency (PTE is not obtained at the resonant frequency of unit resonator. The maximum PTE for relay resonators is obtained at the different resonances of unit resonator. The optimum design of asymmetrical relay is conducted by both the optimum placement and the optimum capacitance of resonators. The optimum placement is found by scanning the positions of the relays and optimum capacitance can be found by using genetic algorithm (GA. The PTEs are enhanced when capacitance is optimally designed by GA according to the position of relays, respectively, and then maximum efficiency is obtained at the optimum placement of relays. The capacitance of the second resonator to nth resonator and the load resistance should be determined for maximum efficiency while the capacitance of the first resonator and the source resistance are obtained for the impedance matching. The simulated and measured results are in good agreement.
Power Constrained High-Level Synthesis of Battery Powered Digital Systems
Nielsen, Sune Fallgaard; Madsen, Jan
2003-01-01
We present a high-level synthesis algorithm solving the combined scheduling, allocation and binding problem minimizing area under both latency and maximum power per clock-cycle constraints. Our approach eliminates the large power spikes, resulting in an increased battery lifetime, a property...... of utmost importance for battery powered embedded systems. Our approach extends the partial-clique partitioning algorithm by introducing power awareness through a heuristic algorithm which bounds the design space to those of power feasible schedules. We have applied our algorithm on a set of dataflow graphs...
Maximum Power Point Tracking of DC To DC Boost Converter Using Sliding Mode Control
Anusuyadevi R
2013-07-01
Full Text Available A sliding mode controller is used to estimate the maximum power point as a reference for it to track that point and force the PV system to operate in this point. In sliding mode control, the trajectories of the system are forced to reach a sliding manifold of surface, where it exhibit desirable features, in finite time and to stay on the manifold for all future time. The load is composed of a battery bank. It is obtained by controlling the duty cycle of a DC-DC converter using sliding mode control. This method has the advantage that it will guarantee the maximum output power possible by the array configuration while considering the dynamic parameters solar irradiance and delivering more power to charge the battery. The proposed system with sliding mode control is tested using MATLAB / SIMULINK platform in which a maximum power is tracked under constant and varying solar irradiance and delivered to the battery which increasing the current that is charging the battery and reduces the charging time.
A Maximum Power Point Tracker with Automatic Step Size Tuning Scheme for Photovoltaic Systems
Kuei-Hsiang Chao
2012-01-01
Full Text Available The purpose of this paper is to study on a novel maximum power point tracking (MPPT method for photovoltaic (PV systems. First, the simulation environment for PV systems is constructed by using PSIM software package. A 516 W PV system established with Kyocera KC40T photovoltaic modules is used as an example to finish the simulation of the proposed MPPT method. When using incremental conductance (INC MPPT method, it usually should consider the tradeoff between the dynamic response and the steady-state oscillation, whereas the proposed modified incremental conductance method based on extension theory can automatically adjust the step size to track the maximum power point (MPP of PV array and effectively improve the dynamic response and steady-state performance of the PV systems, simultaneously. Some simulation and experimental results are made to verify that the proposed extension maximum power point tracking method can provide a good dynamic response and steady-state performance for a photovoltaic power generation system.
The analysis and kinetic energy balance of an upper-level wind maximum during intense convection
Fuelberg, H. E.; Jedlovec, G. J.
1982-01-01
The purpose of this paper is to analyze the formation and maintenance of the upper-level wind maximum which formed between 1800 and 2100 GMT, April 10, 1979, during the AVE-SESAME I period, when intense storms and tornadoes were experienced (the Red River Valley tornado outbreak). Radiosonde stations participating in AVE-SESAME I are plotted (centered on Oklahoma). National Meteorological Center radar summaries near the times of maximum convective activity are mapped, and height and isotach plots are given, where the formation of an upper-level wind maximum over Oklahoma is the most significant feature at 300 mb. The energy balance of the storm region is seen to change dramatically as the wind maximum forms. During much of its lifetime, the upper-level wind maximum is maintained by ageostrophic flow that produces cross-contour generation of kinetic energy and by the upward transport of midtropospheric energy. Two possible mechanisms for the ageostrophic flow are considered.
Maximum Power Point Tracking Algorithms for Grid-Connected Photovoltaic Energy Conversion System
J.Surya Kumari
2013-12-01
Full Text Available As the use of energy is increasing, the requirements for the quality of the supplied electrical energy are more tighten. Energy is the most basic and essential of all resources. As conventional sources of energy are rapidly depleting and the cost of energy is rising, photovoltaic energy becomes a promising alternative source. Photovoltaic (PV generation is becoming increasingly important as a renewable source since it exhibits a great many merits such as cleanness, little maintenance and no noise. The output power of PV arrays is always changing with weather conditions, i.e., solar irradiation and atmospheric temperature. Therefore, a Maximum Power Point Tracking (MPPT control to extract maximum power from the PV arrays at real time becomes indispensable in PV generation system. In recent years, a large number of techniques have been proposed for tracking the maximum power point (MPP. MPPT is used in photovoltaic (PV systems to maximize the photovoltaic array output power, irrespective of the temperature and radiation conditions and of the load electrical characteristics the PV array output power is used to directly control the dc/dc converter, thus reducing the complexity of the system. The resulting system has high-efficiency. This paper presents in details comparison of most popular MPPT algorithms techniques which are Perturb & Observe algorithm(P&O and Improved Perturb & Observe algorithm(IPO. Improved Perturb & Observe algorithm (IPO, is a very promising technique that allows the increase of efficiency and reliability of such systems. Modeling and designing a PV system with Improved Perturb & Observe algorithm (IPO is remarkably more complex than implementing a standard MPPT technique. In this paper, Improved Perturb & Observe algorithm (IPO, system for PV arrays is proposed and analyzed.
Chronic eccentric cycling improves quadriceps muscle structure and maximum cycling power.
Leong, C H; McDermott, W J; Elmer, S J; Martin, J C
2014-06-01
An interesting finding from eccentric exercise training interventions is the presence of muscle hypertrophy without changes in maximum concentric strength and/or power. The lack of improvements in concentric strength and/or power could be due to long lasting suppressive effects on muscle force production following eccentric training. Thus, improvements in concentric strength and/or power might not be detected until muscle tissue has recovered (e. g., several weeks post-training). We evaluated alterations in muscular structure (rectus-femoris, RF, and vastus lateralis, VL, thickness and pennation angles) and maximum concentric cycling power (Pmax) 1-week following 8-weeks of eccentric cycling training (2×/week; 5-10.5 min; 20-55% of Pmax). Pmax was assessed again at 8-weeks post-training. At 1 week post-training, RF and VL thickness increased by 24±4% and 13±2%, respectively, and RF and VL pennation angles increased by 31±4% and 13±1%, respectively (all Peccentric cycling can be a time-effective intervention for improving muscular structure and function in the lower body of healthy individuals. The larger Pmax increase detected at 8-weeks post-training implies that sufficient recovery might be necessary to fully detect changes in muscular power after eccentric cycling training.
Appelbaum, J.; Singer, S.
1989-01-01
A calculation of the starting torque ratio of permanent magnet, series, and shunt-excited dc motors powered by solar cell arrays is presented for two cases, i.e., with and without a maximum-power-point tracker (MPPT). Defining motor torque magnification by the ratio of the motor torque with an MPPT to the motor torque without an MPPT, a magnification of 3 for the permanent magnet motor and a magnification of 7 for both the series and shunt motors are obtained. The study also shows that all motor types are less sensitive to solar insolation variation in systems including MPPTs as compared to systems without MPPTs.
Efficiency at maximum power output of quantum heat engines under finite-time operation
Wang, Jianhui; He, Jizhou; Wu, Zhaoqi
2012-03-01
We study the efficiency at maximum power, ηm, of irreversible quantum Carnot engines (QCEs) that perform finite-time cycles between a hot and a cold reservoir at temperatures Th and Tc, respectively. For QCEs in the reversible limit (long cycle period, zero dissipation), ηm becomes identical to the Carnot efficiency ηC=1-Tc/Th. For QCE cycles in which nonadiabatic dissipation and the time spent on two adiabats are included, the efficiency ηm at maximum power output is bounded from above by ηC/(2-ηC) and from below by ηC/2. In the case of symmetric dissipation, the Curzon-Ahlborn efficiency ηCA=1-Tc/Th is recovered under the condition that the time allocation between the adiabats and the contact time with the reservoir satisfy a certain relation.
Maximum Energy Extraction Control for Wind Power Generation Systems Based on the Fuzzy Controller
Kamal, Elkhatib; Aitouche, Abdel; Mohammed, Walaa; Sobaih, Abdel Azim
2016-10-01
This paper presents a robust controller for a variable speed wind turbine with a squirrel cage induction generator (SCIG). For variable speed wind energy conversion system, the maximum power point tracking (MPPT) is a very important requirement in order to maximize the efficiency. The system is nonlinear with parametric uncertainty and subject to large disturbances. A Takagi-Sugeno (TS) fuzzy logic is used to model the system dynamics. Based on the TS fuzzy model, a controller is developed for MPPT in the presence of disturbances and parametric uncertainties. The proposed technique ensures that the maximum power point (MPP) is determined, the generator speed is controlled and the closed loop system is stable. Robustness of the controller is tested via the variation of model's parameters. Simulation studies clearly indicate the robustness and efficiency of the proposed control scheme compared to other techniques.
Efficiency at maximum power output of quantum heat engines under finite-time operation.
Wang, Jianhui; He, Jizhou; Wu, Zhaoqi
2012-03-01
We study the efficiency at maximum power, η(m), of irreversible quantum Carnot engines (QCEs) that perform finite-time cycles between a hot and a cold reservoir at temperatures T(h) and T(c), respectively. For QCEs in the reversible limit (long cycle period, zero dissipation), η(m) becomes identical to the Carnot efficiency η(C)=1-T(c)/T(h). For QCE cycles in which nonadiabatic dissipation and the time spent on two adiabats are included, the efficiency η(m) at maximum power output is bounded from above by η(C)/(2-η(C)) and from below by η(C)/2. In the case of symmetric dissipation, the Curzon-Ahlborn efficiency η(CA)=1-√(T(c)/T(h)) is recovered under the condition that the time allocation between the adiabats and the contact time with the reservoir satisfy a certain relation.
Robust Controller to Extract the Maximum Power of a Photovoltaic System
OULD CHERCHALI Noureddine
2014-05-01
Full Text Available This paper proposes a technique of intelligent control to track the maximum power point (MPPT of a photovoltaic system . The PV system is non-linear and it is exposed to external perturbations like temperature and solar irradiation. Fuzzy logic control is known for its stability and robustness. FLC is adopted in this work for the improvement and optimization of control performance of a photovoltaic system. Another technique called perturb and observe (P & O is studied and compared with the FLC technique. The PV system is constituted of a photovoltaic panel (PV, a DC-DC converter (Boost and a battery like a load. The simulation results are developed in MATLAB / Simulink software. The results show that the controller based on fuzzy logic is better and faster than the conventional controller perturb and observe (P & O and gives a good maximum power of a photovoltaic generator under different changes of weather conditions.
Hussain Mutlag, Ammar; Mohamed, Azah; Shareef, Hussain
2016-03-01
Maximum power point tracking (MPPT) is normally required to improve the performance of photovoltaic (PV) systems. This paper presents artificial intelligent-based maximum power point tracking (AI-MPPT) by considering three artificial intelligent techniques, namely, artificial neural network (ANN), adaptive neuro fuzzy inference system with seven triangular fuzzy sets (7-tri), and adaptive neuro fuzzy inference system with seven gbell fuzzy sets. The AI-MPPT is designed for the 25 SolarTIFSTF-120P6 PV panels, with the capacity of 3 kW peak. A complete PV system is modelled using 300,000 data samples and simulated in the MATLAB/SIMULINK. The AI-MPPT has been tested under real environmental conditions for two days from 8 am to 18 pm. The results showed that the ANN based MPPT gives the most accurate performance and then followed by the 7-tri-based MPPT.
A maximum power point tracker for photovoltaic energy systems based on fuzzy neural networks
Chun-hua LI; Xin-jian ZHU; Guang-yi CAO; Wan-qi HU; Sheng SUI; Ming-ruo HU
2009-01-01
To extract the maximum power from a photovoltaic (PV) energy system, the real-time maximum power point (MPP) of the PV array must be tracked closely. The non-linear and time-variant characteristics of the PV array and the non-linear and non-minimum phase characteristics of a boost converter make it difficult to track the MPP for traditional control strategies. We propose a fuzzy neural network controller (FNNC), which combines the reasoning capability of fuzzy logical systems and the learning capability of neural networks, to track the MPP. With a derived learning algorithm, the parameters of the FNNC are updated adaptively. A gradient estimator based on a radial basis function neural network is developed to provide the reference information to the FNNC. Simulation results show that the proposed control algorithm provides much better tracking performance compared with the fuzzy logic control algorithm.
Barboza, Luciano Vitoria [Sul-riograndense Federal Institute for Education, Science and Technology (IFSul), Pelotas, RS (Brazil)], E-mail: luciano@pelotas.ifsul.edu.br
2009-07-01
This paper presents an overview about the maximum load ability problem and aims to study the main factors that limit this load ability. Specifically this study focuses its attention on determining which electric system buses influence directly on the power demand supply. The proposed approach uses the conventional maximum load ability method modelled by an optimization problem. The solution of this model is performed using the Interior Point methodology. As consequence of this solution method, the Lagrange multipliers are used as parameters that identify the probable 'bottlenecks' in the electric power system. The study also shows the relationship between the Lagrange multipliers and the cost function in the Interior Point optimization interpreted like sensitivity parameters. In order to illustrate the proposed methodology, the approach was applied to an IEEE test system and to assess its performance, a real equivalent electric system from the South- Southeast region of Brazil was simulated. (author)
Bayu Prima Juliansyah Putra; Aulia Siti Aisjah; Syamsul Arifin
2013-01-01
Salah satu aplikasi yang sering digunakan dalam bidang energi terbarukan adalah panel photovoltaic. Panel ini memiliki prinsip kerja berdasarkan efek photovoltaic dimana lempengan logam akan menghasilkan energi listrik apabila diberi intensitas cahaya. Untuk menghasilkan daya keluaran panel yang maksimal, maka diperlukan suatu algoritma yang biasa disebut Maximum Power Point Tracking (MPPT).MPPT yang diterapkan pada sistem photovoltaic berfungsi untuk mengatur nilai tegangan keluaran panel se...
Fast calculation of the maximum power point of photovoltaic generators under partial shading
Carlos Andres Ramos-Paja; Luz Adriana Trejos-Grisales; Javier Herrera-Murcia
2016-01-01
This paper presents a method to calculate the energy production of photovoltaic generators considering partial shading or mismatched conditions. The proposed method is based on the complete one-diode model including the bypass diode in its exponential form, where the current and voltage values of the modules composing the photovoltaic panel array are calculated without using the Lambert-W function. In addition, the method introduces a procedure to calculate the vicinity of the maximum power p...
Efficiency at maximum power output of linear irreversible Carnot-like heat engines.
Wang, Yang; Tu, Z C
2012-01-01
The efficiency at maximum power output of linear irreversible Carnot-like heat engines is investigated based on the assumption that the rate of irreversible entropy production of the working substance in each "isothermal" process is a quadratic form of the heat exchange rate between the working substance and the reservoir. It is found that the maximum power output corresponds to minimizing the irreversible entropy production in two isothermal processes of the Carnot-like cycle, and that the efficiency at maximum power output has the form η(mP)=η(C)/(2-γη(C)), where η(C) is the Carnot efficiency, while γ depends on the heat transfer coefficients between the working substance and two reservoirs. The value of η(mP) is bounded between η(-)≡η(C)/2 and η(+)≡η(C)/(2-η(C)). These results are consistent with those obtained by Chen and Yan [J. Chem. Phys. 90, 3740 (1989)] based on the endoreversible assumption, those obtained by Esposito et al. [Phys. Rev. Lett. 105, 150603 (2010)] based on the low-dissipation assumption, and those obtained by Schmiedl and Seifert [Europhys. Lett. 81, 20003 (2008)] for stochastic heat engines which in fact also satisfy the low-dissipation assumption. Additionally, we find that the endoreversible assumption happens to hold for Carnot-like heat engines operating at the maximum power output based on our fundamental assumption, and that the Carnot-like heat engines that we focused on do not strictly satisfy the low-dissipation assumption, which implies that the low-dissipation assumption or our fundamental assumption is a sufficient but non-necessary condition for the validity of η(mP)=η(C)/(2-γη(C)) as well as the existence of two bounds, η(-)≡η(C)/2 and η(+)≡η(C)/(2-η(C)).
Maximum Power Point Tracking Using Adaptive Fuzzy Logic control for Photovoltaic System
Anass Ait Laachir
2015-01-01
Full Text Available This work presents an intelligent approach to the improvement and optimization of control performance of a photovoltaic system with maximum power point tracking based on fuzzy logic control. This control was compared with the conventional control based on Perturb &Observe algorithm. The results obtained in Matlab/Simulink under different conditions show a marked improvement in the performance of fuzzy control MPPT of the PV system.
Wenhui Hou
2016-01-01
Full Text Available In order to extract the maximum power from PV system, the maximum power point tracking (MPPT technology has always been applied in PV system. At present, various MPPT control methods have been presented. The perturb and observe (P&O and conductance increment methods are the most popular and widely used under the constant irradiance. However, these methods exhibit fluctuations among the maximum power point (MPP. In addition, the changes of the environmental parameters, such as cloud cover, plant shelter, and the building block, will lead to the radiation change and then have a direct effect on the location of MPP. In this paper, a feasible MPPT method is proposed to adapt to the variation of the irradiance. This work applies the glowworm swarm optimization (GSO algorithm to determine the optimal value of a reference voltage in the PV system. The performance of the proposed GSO algorithm is evaluated by comparing it with the conventional P&O method in terms of tracking speed and accuracy by utilizing MATLAB/SIMULINK. The simulation results demonstrate that the tracking capability of the GSO algorithm is superior to that of the traditional P&O algorithm, particularly under low radiance and sudden mutation irradiance conditions.
Does the Budyko curve reflect a maximum power state of hydrological systems? A backward analysis
Westhoff, Martijn; Zehe, Erwin; Archambeau, Pierre; Dewals, Benjamin
2016-04-01
Almost all catchments plot within a small envelope around the Budyko curve. This apparent behaviour suggests that organizing principles may play a role in the evolution of catchments. In this paper we applied the thermodynamic principle of maximum power as the organizing principle. In a top-down approach we derived mathematical formulations of the relation between relative wetness and gradients driving runoff and evaporation for a simple one-box model. We did this in an inverse manner such that when the conductances are optimized with the maximum power principle, the steady state behaviour of the model leads exactly to a point on the asymptotes of the Budyko curve. Subsequently, we added dynamics in forcing and actual evaporations, causing the Budyko curve to deviate from the asymptotes. Despite the simplicity of the model, catchment observations compare reasonably well with the Budyko curves subject to observed dynamics in rainfall and actual evaporation. Thus by constraining the - with the maximum power principle optimized - model with the asymptotes of the Budyko curve we were able to derive more realistic values of the aridity and evaporation index without any parameter calibration. Future work should focus on better representing the boundary conditions of real catchments and eventually adding more complexity to the model.
Efficiency at maximum power of thermochemical engines with near-independent particles.
Luo, Xiaoguang; Liu, Nian; Qiu, Teng
2016-03-01
Two-reservoir thermochemical engines are established by using near-independent particles (including Maxwell-Boltzmann, Fermi-Dirac, and Bose-Einstein particles) as the working substance. Particle and heat fluxes can be formed based on the temperature and chemical potential gradients between two different reservoirs. A rectangular-type energy filter with width Γ is introduced for each engine to weaken the coupling between the particle and heat fluxes. The efficiency at maximum power of each particle system decreases monotonously from an upper bound η(+) to a lower bound η(-) when Γ increases from 0 to ∞. It is found that the η(+) values for all three systems are bounded by η(C)/2 ≤ η(+) ≤ η(C)/(2-η(C)) due to strong coupling, where η(C) is the Carnot efficiency. For the Bose-Einstein system, it is found that the upper bound is approximated by the Curzon-Ahlborn efficiency: η(CA)=1-sqrt[1-η(C)]. When Γ → ∞, the intrinsic maximum powers are proportional to the square of the temperature difference of the two reservoirs for all three systems, and the corresponding lower bounds of efficiency at maximum power can be simplified in the same form of η(-)=η(C)/[1+a(0)(2-η(C))].
Efficiency at maximum power of thermochemical engines with near-independent particles
Luo, Xiaoguang; Liu, Nian; Qiu, Teng
2016-03-01
Two-reservoir thermochemical engines are established by using near-independent particles (including Maxwell-Boltzmann, Fermi-Dirac, and Bose-Einstein particles) as the working substance. Particle and heat fluxes can be formed based on the temperature and chemical potential gradients between two different reservoirs. A rectangular-type energy filter with width Γ is introduced for each engine to weaken the coupling between the particle and heat fluxes. The efficiency at maximum power of each particle system decreases monotonously from an upper bound η+ to a lower bound η- when Γ increases from 0 to ∞ . It is found that the η+ values for all three systems are bounded by ηC/2 ≤η+≤ηC/(2 -ηC ) due to strong coupling, where ηC is the Carnot efficiency. For the Bose-Einstein system, it is found that the upper bound is approximated by the Curzon-Ahlborn efficiency: ηCA=1 -√{1 -ηC } . When Γ →∞ , the intrinsic maximum powers are proportional to the square of the temperature difference of the two reservoirs for all three systems, and the corresponding lower bounds of efficiency at maximum power can be simplified in the same form of η-=ηC/[1 +a0(2 -ηC ) ] .
Sliding-Mode Controller for Maximum Power Point Tracking in Grid-Connected Photovoltaic Systems
Paula Andrea Ortiz Valencia
2015-11-01
Full Text Available The maximum power point tracking (MPPT of photovoltaic systems must be as fast and accurate as possible to increase the power production, which eventually increases the PV system profitability. This paper proposes and mathematically analyses a sliding-mode controller to provide a fast and accurate maximum power point tracking in grid-connected photovoltaic systems using a single control stage. This approach avoids the circular dependency in the design of classical cascade controllers used to optimize the photovoltaic system operation, and at the same time, it reduces the number of controllers and avoids the use of linearized models to provide global stability in all the operation range. Such a compact solution also reduces the system cost and implementation complexity. To ensure the stability of the proposed solution, detailed mathematical analyses are performed to demonstrate the fulfillment of the transversality, reachability and equivalent control conditions. Finally, the performance of the proposed solution is validated using detailed simulations, executed in the power electronics simulator PSIM, accounting for both environmental and load perturbations.
Maximum Output Power Control System of Variable-Speed Small Wind Generators
Amano, Yoko; Kajiwara, Hiroyuki
This paper proposes a maximum output power control system of variable-speed small wind generators. Paying attention to an optimum rotational speed of a single phase AC wind generator which can obtain maximum output power according to natural wind speed, the proposed method adjusts the rotational speed of the single phase AC generator to the optimum rotational speed. Since this adjustment is realized on line so that it can be adapted for variable-speed wind, a generated power brake links directly with the single phase AC generator, and the rotational speed of the single phase AC generator is adjusted by controlling the current that flows the FET (Field-Effect Transistor) device as the generated power brake. In order to reduce heat loss of the FET device, the PWM (Pulse Width Modulation) controller is introduced. Moreover, the experimental system of the proposed method is constituted and the experiment is performed. Finally, the validity and the practicality of the proposed method are confirmed by experimental results.
Nadhir, Ahmad; Naba, Agus; Hiyama, Takashi
An optimal control for maximizing extraction of power in variable-speed wind energy conversion system is presented. Intelligent gradient detection by fuzzy inference system (FIS) in maximum power point tracking control is proposed to achieve power curve operating near optimal point. Speed rotor reference can be adjusted by maximum power point tracking fuzzy controller (MPPTFC) such that the turbine operates around maximum power. Power curve model can be modelled by using adaptive neuro fuzzy inference system (ANFIS). It is required to simply well estimate just a few number of maximum power points corresponding to optimum generator rotor speed under varying wind speed, implying its training can be done with less effort. Using the trained fuzzy model, some estimated maximum power points as well as their corresponding generator rotor speed and wind speed are determined, from which a linear wind speed feedback controller (LWSFC) capable of producing optimum generator speed can be obtained. Applied to a squirrel-cage induction generator based wind energy conversion system, MPPTFC and LWSFC could maximize extraction of the wind energy, verified by a power coefficient stay at its maximum almost all the time and an actual power line close to a maximum power efficiency line reference.
OPTIMIZING THE SHAPE OF ROTOR BLADES FOR MAXIMUM POWER EXTRACTION IN MARINE CURRENT TURBINES
J.A. Esfahani
2012-12-01
Full Text Available In this paper the shape of rotor blades in Marine Current Turbines (MCTs are investigated. The evaluation of hydrodynamic loads on blades is performed based on the Blade Element Momentum (BEM theory. The shape of blades is optimized according to the main parameters in the configuration and operation of these devices. The optimization is conducted based on the ability of the blades to harness the maximum energy during operating. The main parameters investigated are the tip speed ratio and angle of attack. Furthermore, the influence of these parameters on the maximum energy extraction from fluid flow over a hydrofoil is evaluated. It is shown that the effect of the angle of attack on power extraction is greater than that of the tip speed ratio, while both are found to be significant. Additionally, the proper angle of attack is the angle at which the lift to drag ratio is at its maximum value. However, if a proper angle of attack is chosen, the variations in power coefficient would not be effectively changed with small variations in the tip speed ratio.
Yu, Hwa-Lung; Wang, Chih-Hsin
2013-02-05
Understanding the daily changes in ambient air quality concentrations is important to the assessing human exposure and environmental health. However, the fine temporal scales (e.g., hourly) involved in this assessment often lead to high variability in air quality concentrations. This is because of the complex short-term physical and chemical mechanisms among the pollutants. Consequently, high heterogeneity is usually present in not only the averaged pollution levels, but also the intraday variance levels of the daily observations of ambient concentration across space and time. This characteristic decreases the estimation performance of common techniques. This study proposes a novel quantile-based Bayesian maximum entropy (QBME) method to account for the nonstationary and nonhomogeneous characteristics of ambient air pollution dynamics. The QBME method characterizes the spatiotemporal dependence among the ambient air quality levels based on their location-specific quantiles and accounts for spatiotemporal variations using a local weighted smoothing technique. The epistemic framework of the QBME method can allow researchers to further consider the uncertainty of space-time observations. This study presents the spatiotemporal modeling of daily CO and PM10 concentrations across Taiwan from 1998 to 2009 using the QBME method. Results show that the QBME method can effectively improve estimation accuracy in terms of lower mean absolute errors and standard deviations over space and time, especially for pollutants with strong nonhomogeneous variances across space. In addition, the epistemic framework can allow researchers to assimilate the site-specific secondary information where the observations are absent because of the common preferential sampling issues of environmental data. The proposed QBME method provides a practical and powerful framework for the spatiotemporal modeling of ambient pollutants.
Wang, Heming; Park, Jae-Do; Ren, Zhiyong
2012-05-01
Microbial fuel cell (MFC) technology offers a sustainable approach to harvest electricity from biodegradable materials. Energy production from MFCs has been demonstrated using external resistors or charge pumps, but such methods can only dissipate energy through heat or receive electrons passively from the MFC without any controllability. This study developed a new approach and system that can actively extract energy from MFC reactors at any operating point without using any resistors, especially at the peak power point to maximize energy production. Results show that power harvesting from a recirculating-flow MFC can be well maintained by the maximum power point circuit (MPPC) at its peak power point, while a charge pump was not able to change operating point due to current limitation. Within 18-h test, the energy gained from the MPPC was 76.8 J, 76 times higher than the charge pump (1.0 J) that was commonly used in MFC studies. Both conditions resulted in similar organic removal, but the Coulombic efficiency obtained from the MPPC was 21 times higher than that of the charge pump. Different numbers of capacitors could be used in the MPPC for various energy storage requirements and power supply, and the energy conversion efficiency of the MPPC was further characterized to identify key factors for system improvement. This active energy harvesting approach provides a new perspective for energy harvesting that can maximize MFC energy generation and system controllability.
Matching of Silicon Thin-Film Tandem Solar Cells for Maximum Power Output
C. Ulbrich
2013-01-01
Full Text Available We present a meaningful characterization method for tandem solar cells. The experimental method allows for optimizing the output power instead of the current. Furthermore, it enables the extraction of the approximate AM1.5g efficiency when working with noncalibrated spectra. Current matching of tandem solar cells under short-circuit condition maximizes the output current but is disadvantageous for the overall fill factor and as a consequence does not imply an optimization of the output power of the device. We apply the matching condition to the maximum power output; that is, a stack of solar cells is power matched if the power output of each subcell is maximal at equal subcell currents. The new measurement procedure uses additional light-emitting diodes as bias light in the JV characterization of tandem solar cells. Using a characterized reference tandem solar cell, such as a hydrogenated amorphous/microcrystalline silicon tandem, it is possible to extract the AM1.5g efficiency from tandems of the same technology also under noncalibrated spectra.
Maximum Likelihood Analysis of a Two-Level Nonlinear Structural Equation Model with Fixed Covariates
Lee, Sik-Yum; Song, Xin-Yuan
2005-01-01
In this article, a maximum likelihood (ML) approach for analyzing a rather general two-level structural equation model is developed for hierarchically structured data that are very common in educational and/or behavioral research. The proposed two-level model can accommodate nonlinear causal relations among latent variables as well as effects…
Overview of Maximum Power Point Tracking Techniques for Photovoltaic Energy Production Systems
2017-01-01
A substantial growth of the installed photovoltaic (PV) systems capacity has occurred around the world during the last decade, thus enhancing the availability of electric energy in an environmentally friendly way. The maximum power point tracking (MPPT) technique enables to maximize the energy...... production of PV sources, despite the stochastically varying solar irradiation and ambient temperature conditions. Thereby, the overall efficiency of the PV energy production system is increased. Numerous techniques have been presented during the last decades for implementing the MPPT process in a PV system...
Efficiency and its bounds for thermal engines at maximum power using Newton's law of cooling
Yan, H; Guo, H.
2012-01-01
We study a thermal engine model for which Newton's cooling law is obeyed during heat transfer processes. The thermal efficiency and its bounds at maximum output power are derived and discussed. This model, though quite simple, can be applied not only to Carnot engines but also to four other types of engines. For the long thermal contact time limit, new bounds, tighter than what were known before, are obtained. In this case, this model can simulate Otto, Joule-Brayton, Diesel, and Atkinson eng...
Wang, Jianhui; He, Jizhou
2012-11-01
We investigate the efficiency at the maximum power output (EMP) of an irreversible Carnot engine performing finite-time cycles between two reservoirs at constant temperatures T(h) and T(c) (Carnot efficiency, whether the internally dissipative friction is considered or not. When dissipations of two "isothermal" and two "adiabatic" processes are symmetric, respectively, and the time allocation between the adiabats and the contact time with the reservoir satisfy a certain relation, the Curzon-Ahlborn (CA) efficiency η(CA) = 1-sqrt[T(c)/T(h)] is derived.
Larbes, C.; Ait Cheikh, S.M.; Obeidi, T.; Zerguerras, A. [Laboratoire des Dispositifs de Communication et de Conversion Photovoltaique, Departement d' Electronique, Ecole Nationale Polytechnique, 10, Avenue Hassen Badi, El Harrach, Alger 16200 (Algeria)
2009-10-15
This paper presents an intelligent control method for the maximum power point tracking (MPPT) of a photovoltaic system under variable temperature and irradiance conditions. First, for the purpose of comparison and because of its proven and good performances, the perturbation and observation (P and O) technique is briefly introduced. A fuzzy logic controller based MPPT (FLC) is then proposed which has shown better performances compared to the P and O MPPT based approach. The proposed FLC has been also improved using genetic algorithms (GA) for optimisation. Different development stages are presented and the optimized fuzzy logic MPPT controller (OFLC) is then simulated and evaluated, which has shown better performances. (author)
Hadi Sefidgar
2014-06-01
Full Text Available in this paper, a fuzzy logic control (FLC is proposed for maximum power point tracking (MPPT in wind turbine connection to Permanent Magnet Synchronous Generator (PMSG. The proposed fuzzy logic controller tracks the maximum power point (MPP by measurements the load voltage and current. This controller calculates the load power and sent through the fuzzy logic system. The main goal of this paper is design of the fuzzy logic controller in the model of DC-DC converter (boost converter. This method allows the MPPT controller output (duty cycle adjusts the voltage input to the converter to track the maximum power point of the wind generator.
Atik, L.; Petit, P.; Sawicki, J. P.; Ternifi, Z. T.; Bachir, G.; Della, M.; Aillerie, M.
2017-02-01
Solar panels have a nonlinear voltage-current characteristic, with a distinct maximum power point (MPP), which depends on the environmental factors, such as temperature and irradiation. In order to continuously harvest maximum power from the solar panels, they have to operate at their MPP despite the inevitable changes in the environment. Various methods for maximum power point tracking (MPPT) were developed and finally implemented in solar power electronic controllers to increase the efficiency in the electricity production originate from renewables. In this paper we compare using Matlab tools Simulink, two different MPP tracking methods, which are, fuzzy logic control (FL) and sliding mode control (SMC), considering their efficiency in solar energy production.
Wei Wang
2012-05-01
Full Text Available This paper proposes a novel optimal current given (OCG maximum power point tracking (MPPT control strategy based on the theory of power feedback and hill climb searching (HCS for a permanent magnet direct drive wind energy conversion system (WECS. The presented strategy not only has the advantages of not needing the wind speed and wind turbine characteristics of the traditional HCS method, but it also improves the stability and accuracy of MPPT by estimating the exact loss torque. The OCG MPPT control strategy is first carried out by simulation, then an experimental platform based on the dSPACE1103 controller is built and a 5.5 kW permanent magnet synchronous generator (PMSG is tested. Furthermore, the proposed method is compared experimentally with the traditional optimum tip speed ratio (TSR MPPT control. The experiments verify the effectiveness of the proposed OCG MPPT strategy and demonstrate its better performance than the traditional TSR MPPT control.
Dithering Digital Ripple Correlation Control for Photovoltaic Maximum Power Point Tracking
Barth, C; Pilawa-Podgurski, RCN
2015-08-01
This study demonstrates a new method for rapid and precise maximum power point tracking in photovoltaic (PV) applications using dithered PWM control. Constraints imposed by efficiency, cost, and component size limit the available PWM resolution of a power converter, and may in turn limit the MPP tracking efficiency of the PV system. In these scenarios, PWM dithering can be used to improve average PWM resolution. In this study, we present a control technique that uses ripple correlation control (RCC) on the dithering ripple, thereby achieving simultaneous fast tracking speed and high tracking accuracy. Moreover, the proposed method solves some of the practical challenges that have to date limited the effectiveness of RCC in solar PV applications. We present a theoretical derivation of the principles behind dithering digital ripple correlation control, as well as experimental results that show excellent tracking speed and accuracy with basic hardware requirements.
Wu, Feilong; He, Jizhou; Ma, Yongli; Wang, Jianhui
2014-12-01
We consider the efficiency at maximum power of a quantum Otto engine, which uses a spin or a harmonic system as its working substance and works between two heat reservoirs at constant temperatures T(h) and T(c) (power based on these two different kinds of quantum systems are bounded from the upper side by the same expression η(mp)≤η(+)≡η(C)(2)/[η(C)-(1-η(C))ln(1-η(C))] with η(C)=1-T(c)/T(h) as the Carnot efficiency. This expression η(mp) possesses the same universality of the CA efficiency η(CA)=1-√(1-η(C)) at small relative temperature difference. Within the context of irreversible thermodynamics, we calculate the Onsager coefficients and show that the value of η(CA) is indeed the upper bound of EMP for an Otto engine working in the linear-response regime.
Elhussain, O. A.; Abdel-Magid, T. I. M.
2016-08-01
Mono-Crystalline solar cell module is experimentally conducted in Khartoum, Sudan to study the difference between maximum empirical value of peak Watt and maximum value of thermal power produced in field under highly sufficient solar conditions. Field measurements are recorded for incident solar radiation, produced voltage, current and temperature at several time intervals during sun shine period. The thermal power system has been calculated using fundamental principles of heat transfer. The study shows that solar power for considered module could not attain the empirical peak power irrespective to maximum value of direct incident solar radiation and maximum temperature gained. A loss of about 6% of power can be considered as the difference between field measurements and the manufacturer's indicated empirical value. Solar cell exhibits 94% efficiency in comparison with manufacturer's provided data, and is 3'% more efficient in thermal energy production than in electrical power extraction for hot-dry climate conditions.
Bounds and phase diagram of efficiency at maximum power for tight-coupling molecular motors.
Tu, Z C
2013-02-01
The efficiency at maximum power (EMP) for tight-coupling molecular motors is investigated within the framework of irreversible thermodynamics. It is found that the EMP depends merely on the constitutive relation between the thermodynamic current and force. The motors are classified into four generic types (linear, superlinear, sublinear, and mixed types) according to the characteristics of the constitutive relation, and then the corresponding ranges of the EMP for these four types of molecular motors are obtained. The exact bounds of the EMP are derived and expressed as the explicit functions of the free energy released by the fuel in each motor step. A phase diagram is constructed which clearly shows how the region where the parameters (the load distribution factor and the free energy released by the fuel in each motor step) are located can determine whether the value of the EMP is larger or smaller than 1/2. This phase diagram reveals that motors using ATP as fuel under physiological conditions can work at maximum power with higher efficiency (> 1/2) for a small load distribution factor (< 0.1).
Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph
2012-03-01
Energy conversion efficiency at maximum output power, which embodies the essential characteristics of heat engines, is the main focus of the present work. The so-called Curzon and Ahlborn efficiency η(CA) is commonly believed to be an absolute reference for real heat engines; however, a different but general expression for the case of stochastic heat engines, η(SS), was recently found and then extended to low-dissipation engines. The discrepancy between η(CA) and η(SS) is here analyzed considering different irreversibility sources of heat engines, of both internal and external types. To this end, we choose a thermoelectric generator operating in the strong-coupling regime as a physical system to qualitatively and quantitatively study the impact of the nature of irreversibility on the efficiency at maximum output power. In the limit of pure external dissipation, we obtain η(CA), while η(SS) corresponds to the case of pure internal dissipation. A continuous transition between from one extreme to the other, which may be operated by tuning the different sources of irreversibility, also is evidenced.
Level Shifter Design for Low Power Applications
Manoj Kumar
2010-10-01
Full Text Available With scaling of Vt sub-threshold leakage power is increasing and expected to become significant part oftotal power consumption.In present work three new configurations of level shifters for low powerapplication in 0.35μm technology have been presented. The proposed circuits utilize the merits ofstacking technique with smaller leakage current and reduction in leakage power. Conventional levelshifter has been improved by addition of three NMOS transistors, which shows total power consumptionof 402.2264pW as compared to 0.49833nW with existing circuit. Single supply level shifter has beenmodified with addition of two NMOS transistors that gives total power consumption of 108.641pW ascompared to 31.06nW. Another circuit, contention mitigated level shifter (CMLS with three additionaltransistors shows total power consumption of 396.75pW as compared to 0.4937354nW. Three proposedcircuit’s shows better performance in terms of power consumption with a little conciliation in delay.Output level of 3.3V has been obtained with input pulse of 1.6V for all proposed circuits.
Beltran, H.; Perez, E.; Chen, Zhe
2009-01-01
This paper describes a Fixed Maximum Power Point analog control used in a step-down Pulse Width Modulated power converter. The DC/DC converter drives a DC motor used in small water pumping installations, without any electric storage device. The power supply is provided by PV panels working around...
Ouerdane, H.; Apertet, Y.; Goupil, C.; Lecoeur, Ph.
2015-07-01
Classical equilibrium thermodynamics is a theory of principles, which was built from empirical knowledge and debates on the nature and the use of heat as a means to produce motive power. By the beginning of the 20th century, the principles of thermodynamics were summarized into the so-called four laws, which were, as it turns out, definitive negative answers to the doomed quests for perpetual motion machines. As a matter of fact, one result of Sadi Carnot's work was precisely that the heat-to-work conversion process is fundamentally limited; as such, it is considered as a first version of the second law of thermodynamics. Although it was derived from Carnot's unrealistic model, the upper bound on the thermodynamic conversion efficiency, known as the Carnot efficiency, became a paradigm as the next target after the failure of the perpetual motion ideal. In the 1950's, Jacques Yvon published a conference paper containing the necessary ingredients for a new class of models, and even a formula, not so different from that of Carnot's efficiency, which later would become the new efficiency reference. Yvon's first analysis of a model of engine producing power, connected to heat source and sink through heat exchangers, went fairly unnoticed for twenty years, until Frank Curzon and Boye Ahlborn published their pedagogical paper about the effect of finite heat transfer on output power limitation and their derivation of the efficiency at maximum power, now mostly known as the Curzon-Ahlborn (CA) efficiency. The notion of finite rate explicitly introduced time in thermodynamics, and its significance cannot be overlooked as shown by the wealth of works devoted to what is now known as finite-time thermodynamics since the end of the 1970's. The favorable comparison of the CA efficiency to actual values led many to consider it as a universal upper bound for real heat engines, but things are not so straightforward that a simple formula may account for a variety of situations. The
Efficient Photovoltaic System Maximum Power Point Tracking Using a New Technique
Mehdi Seyedmahmoudian
2016-03-01
Full Text Available Partial shading is an unavoidable condition which significantly reduces the efficiency and stability of a photovoltaic (PV system. When partial shading occurs the system has multiple-peak output power characteristics. In order to track the global maximum power point (GMPP within an appropriate period a reliable technique is required. Conventional techniques such as hill climbing and perturbation and observation (P&O are inadequate in tracking the GMPP subject to this condition resulting in a dramatic reduction in the efficiency of the PV system. Recent artificial intelligence methods have been proposed, however they have a higher computational cost, slower processing time and increased oscillations which results in further instability at the output of the PV system. This paper proposes a fast and efficient technique based on Radial Movement Optimization (RMO for detecting the GMPP under partial shading conditions. The paper begins with a brief description of the behavior of PV systems under partial shading conditions followed by the introduction of the new RMO-based technique for GMPP tracking. Finally, results are presented to demonstration the performance of the proposed technique under different partial shading conditions. The results are compared with those of the PSO method, one of the most widely used methods in the literature. Four factors, namely convergence speed, efficiency (power loss reduction, stability (oscillation reduction and computational cost, are considered in the comparison with the PSO technique.
Xiang Luo
2016-07-01
Full Text Available Recently, Vernier permanent magnet (VPM machines, one special case of magnetic flux-modulated (MFM machines, benefiting from their compact, simple construction and low-speed/ high-torque characteristics, have been receiving increasing interest. In this paper, the Vernier structure is integrated with an axial-flux PM machine to obtain the magnetic gear effect and produce an improved torque density for direct-drive wind power generation application. Another advantage of the proposed machine is that the stator flux rotating speed can be relatively high when the shaft speed is low. With this benefit, sensorless control strategy can be easily implemented in a wide speed range. In this paper, an improved sliding mode observer (SMO is proposed to estimate the rotor position and the speed of the proposed machine. With the estimated shaft speeds, the maximum power point tracking (MPPT control strategy is applied to maximize the wind power extraction. The machine design and the sensorless MPPT control strategy are verified by finite element analysis and experimental verification.
Muhammad Riazul Hamid
2016-06-01
Full Text Available This paper describes how to implement MPPT using the most popular switching power supply topology. There are many published works on this topic, but only a tiny portion of them show how to actually implement the algorithms in hardware, as well as state common problems and pitfalls. In our work to keep the design simple we have used Arduino Nano. It has features like: LCD display, Led Indication and it is equipped with various protections to protect the circuitry from abnormal condition. This design is suitable for a 50W solar panel to charge a commonly used 12V lead acid battery. As the maximum power point (MPP of photovoltaic (PV power generation systems changes with changing atmospheric conditions (e.g. solar radiation and temperature, an important consideration in the design of efficient PV systems is to track the MPP correctly. We have implemented the most common MPPT algorithm named Perturb and Observe (PO to control the output of a synchronous buck-converter
Design of a control scheme for a maximum power extraction in low power wind turbine-generator system
Henao Bravo, Elkin Edilberto
This document presents the modeling of a wind turbine-generator system and developing a control scheme for maximum power extraction. The system comprises a low-power variable speed wind rotor coupled to a squirrel cage induction generator through gearbox. The generator delivers electrical energy to a DC load through a PWM three phase rectifier which control variables are duty cycle and the fundamental frequency of the modulated signal. The control scheme maintains constant relationship voltage/frequency in the stator of the generator to operate the machine with constant air gap flow at its nominal value, thereby decreasing electrical losses in the circuit of the stator and rotor. The controller is based on MPPT algorithms for determining the operating point the system and achieve the proper mechanical speed shaft. The performance is evaluated through simulations in MatlabRTM/simulink. and presents this type of control as a good alternative for handling low-power wind turbine-generator systems effectively and efficiently
40 CFR 141.53 - Maximum contaminant level goals for disinfection byproducts.
2010-07-01
... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Maximum contaminant level goals for disinfection byproducts. 141.53 Section 141.53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... disinfection byproducts. MCLGs for the following disinfection byproducts are as indicated: Disinfection...
Constrained Maximum Likelihood Estimation for Two-Level Mean and Covariance Structure Models
Bentler, Peter M.; Liang, Jiajuan; Tang, Man-Lai; Yuan, Ke-Hai
2011-01-01
Maximum likelihood is commonly used for the estimation of model parameters in the analysis of two-level structural equation models. Constraints on model parameters could be encountered in some situations such as equal factor loadings for different factors. Linear constraints are the most common ones and they are relatively easy to handle in…
Architectural-level power estimation and experimentation
Ye, Wu
With the emergence of a plethora of embedded and portable applications and ever increasing integration levels, power dissipation of integrated circuits has moved to the forefront as a design constraint. Recent years have also seen a significant trend towards designs starting at the architectural (or RT) level. Those demand accurate yet fast RT level power estimation methodologies and tools. This thesis addresses issues and experiments associate with architectural level power estimation. An execution driven, cycle-accurate RT level power simulator, SimplePower, was developed using transition-sensitive energy models. It is based on the architecture of a five-stage pipelined RISC datapath for both 0.35mum and 0.8mum technology and can execute the integer subset of the instruction set of SimpleScalar . SimplePower measures the energy consumed in the datapath, memory and on-chip buses. During the development of SimplePower , a partitioning power modeling technique was proposed to model the energy consumed in complex functional units. The accuracy of this technique was validated with HSPICE simulation results for a register file and a shifter. A novel, selectively gated pipeline register optimization technique was proposed to reduce the datapath energy consumption. It uses the decoded control signals to selectively gate the data fields of the pipeline registers. Simulation results show that this technique can reduce the datapath energy consumption by 18--36% for a set of benchmarks. A low-level back-end compiler optimization, register relabeling, was applied to reduce the on-chip instruction cache data bus switch activities. Its impact was evaluated by SimplePower. Results show that it can reduce the energy consumed in the instruction data buses by 3.55--16.90%. A quantitative evaluation was conducted for the impact of six state-of-art high-level compilation techniques on both datapath and memory energy consumption. The experimental results provide a valuable insight for
Different types of maximum power point tracking techniques for renewable energy systems: A survey
Khan, Mohammad Junaid; Shukla, Praveen; Mustafa, Rashid; Chatterji, S.; Mathew, Lini
2016-03-01
Global demand for electricity is increasing while production of energy from fossil fuels is declining and therefore the obvious choice of the clean energy source that is abundant and could provide security for development future is energy from the sun. In this paper, the characteristic of the supply voltage of the photovoltaic generator is nonlinear and exhibits multiple peaks, including many local peaks and a global peak in non-uniform irradiance. To keep global peak, MPPT is the important component of photovoltaic systems. Although many review articles discussed conventional techniques such as P & O, incremental conductance, the correlation ripple control and very few attempts have been made with intelligent MPPT techniques. This document also discusses different algorithms based on fuzzy logic, Ant Colony Optimization, Genetic Algorithm, artificial neural networks, Particle Swarm Optimization Algorithm Firefly, Extremum seeking control method and hybrid methods applied to the monitoring of maximum value of power at point in systems of photovoltaic under changing conditions of irradiance.
Vaudrey, A; Lanzetta, F; Glises, R
2009-01-01
Producing useful electrical work in consuming chemical energy, the fuel cell have to reject heat to its surrounding. However, as it occurs for any other type of engine, this thermal energy cannot be exchanged in an isothermal way in finite time through finite areas. As it was already done for various types of systems, we study the fuel cell within the finite time thermodynamics framework and define an endoreversible fuel cell. Considering different types of heat transfer laws, we obtain an optimal value of the operating temperature, corresponding to a maximum produced power. This analysis is a first step of a thermodynamical approach of design of thermal management devices, taking into account performances of the whole system.
The maximum power efficiency 1-√τ: Research, education, and bibliometric relevance
Calvo Hernández, A.; Roco, J. M. M.; Medina, A.; Velasco, S.; Guzmán-Vargas, L.
2015-07-01
The well-known efficiency at maximum power for a cyclic system working between hot T h and low T c temperatures given by the equation 1-√ τ( τ= T c /T h), has become a landmark result with regards to the thermodynamic optimization of a great variety of energy converters. Its wide applicability and sole dependence on the external heat bath temperatures (as the Carnot efficiency does) allows for an easy comparison with experimental efficiencies leading to a striking fair agreement. Reversible, finite-time, and linear-irreversible derivations are analyzed in order to show a broader perspective about its meaning from both researching and pedagogical point of views. Its scientific relevance and historical development are also analyzed in this work by means of some bibliometric data. This article is supplemented with comments by Hong Qian and a final reply by the authors.
Koofigar, Hamid Reza
2016-01-01
The problem of maximum power point tracking (MPPT) in photovoltaic (PV) systems, despite the model uncertainties and the variations in environmental circumstances, is addressed. Introducing a mathematical description, an adaptive sliding mode control (ASMC) algorithm is first developed. Unlike many previous investigations, the output voltage is not required to be sensed and the upper bound of system uncertainties and the variations of irradiance and temperature are not required to be known. Estimating the output voltage by an update law, an adaptive-based H∞ tracking algorithm is then developed for the case the perturbations are energy-bounded. The stability analysis is presented for the proposed tracking control schemes, based on the Lyapunov stability theorem. From a comparison viewpoint, some numerical and experimental studies are also presented and discussed.
Dhara, Chirag; Kleidon, Axel
2015-01-01
Convective and radiative cooling are the two principle mechanisms by which the Earth's surface transfers heat into the atmosphere and that shape surface temperature. However, this partitioning is not sufficiently constrained by energy and mass balances alone. We use a simple energy balance model in which convective fluxes and surface temperatures are determined with the additional thermodynamic limit of maximum convective power. We then show that the broad geographic variation of heat fluxes and surface temperatures in the climatological mean compare very well with the ERA-Interim reanalysis over land and ocean. We also show that the estimates depend considerably on the formulation of longwave radiative transfer and that a spatially uniform offset is related to the assumed cold temperature sink at which the heat engine operates.
Improved incremental conductance method for maximum power point tracking using cuk converter
M. Saad Saoud
2014-03-01
Full Text Available The Algerian government relies on a strategy focused on the development of inexhaustible resources such as solar and uses to diversify energy sources and prepare the Algeria of tomorrow: about 40% of the production of electricity for domestic consumption will be from renewable sources by 2030, Therefore it is necessary to concentrate our forces in order to reduce the application costs and to increment their performances, Their performance is evaluated and compared through theoretical analysis and digital simulation. This paper presents simulation of improved incremental conductance method for maximum power point tracking (MPPT using DC-DC cuk converter. This improved algorithm is used to track MPPs because it performs precise control under rapidly changing Atmospheric conditions, Matlab/ Simulink were employed for simulation studies.
Determination of maximum power transfer conditions of bimorph piezoelectric energy harvesters
Ahmad, Mahmoud Al
2012-07-23
In this paper, a method to find the maximum power transfer conditions in bimorph piezoelectric-based harvesters is proposed. Explicitly, we derive a closed form expression that relates the load resistance to the mechanical parameters describing the bimorph based on the electromechanical, single degree of freedom, analogy. Further, by taking into account the intrinsic capacitance of the piezoelectric harvester, a more descriptive expression of the resonant frequency in piezoelectric bimorphs was derived. In interest of impartiality, we apply the proposed philosophy on previously published experimental results and compare it with other reported hypotheses. It was found that the proposed method was able to predict the actual optimum load resistance more accurately than other methods reported in the literature. © 2012 American Institute of Physics.
Efficiency and its bounds for thermal engines at maximum power using Newton's law of cooling.
Yan, H; Guo, Hao
2012-01-01
We study a thermal engine model for which Newton's cooling law is obeyed during heat transfer processes. The thermal efficiency and its bounds at maximum output power are derived and discussed. This model, though quite simple, can be applied not only to Carnot engines but also to four other types of engines. For the long thermal contact time limit, new bounds, tighter than what were known before, are obtained. In this case, this model can simulate Otto, Joule-Brayton, Diesel, and Atkinson engines. While in the short contact time limit, which corresponds to the Carnot cycle, the same efficiency bounds as that from Esposito et al. [Phys. Rev. Lett. 105, 150603 (2010)] are derived. In both cases, the thermal efficiency decreases as the ratio between the heat capacities of the working medium during heating and cooling stages increases. This might provide instructions for designing real engines.
Efficiency and its bounds for thermal engines at maximum power using Newton's law of cooling
Yan, H.; Guo, Hao
2012-01-01
We study a thermal engine model for which Newton's cooling law is obeyed during heat transfer processes. The thermal efficiency and its bounds at maximum output power are derived and discussed. This model, though quite simple, can be applied not only to Carnot engines but also to four other types of engines. For the long thermal contact time limit, new bounds, tighter than what were known before, are obtained. In this case, this model can simulate Otto, Joule-Brayton, Diesel, and Atkinson engines. While in the short contact time limit, which corresponds to the Carnot cycle, the same efficiency bounds as that from Esposito [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.105.150603 105, 150603 (2010)] are derived. In both cases, the thermal efficiency decreases as the ratio between the heat capacities of the working medium during heating and cooling stages increases. This might provide instructions for designing real engines.
Efficiency at maximum power of a quantum heat engine based on two coupled oscillators.
Wang, Jianhui; Ye, Zhuolin; Lai, Yiming; Li, Weisheng; He, Jizhou
2015-06-01
We propose and theoretically investigate a system of two coupled harmonic oscillators as a heat engine. We show how these two coupled oscillators within undamped regime can be controlled to realize an Otto cycle that consists of two adiabatic and two isochoric processes. During the two isochores the harmonic system is embedded in two heat reservoirs at constant temperatures T(h) and T(c)(semigroup approach to model the thermal relaxation dynamics along the two isochoric processes, and we find the upper bound of efficiency at maximum power (EMP) η* to be a function of the Carnot efficiency η(C)(=1-T(c)/T(h)): η*≤η(+)≡η(C)(2)/[η(C)-(1-η(C))ln(1-η(C))], identical to those previously derived from ideal (noninteracting) microscopic, mesoscopic, and macroscopic systems.
Abhishek Khanna
2012-01-01
Full Text Available We revisit the problem of optimal power extraction in four-step cycles (two adiabatic and two heat-transfer branches when the finite-rate heat transfer obeys a linear law and the heat reservoirs have finite heat capacities. The heat-transfer branch follows a polytropic process in which the heat capacity of the working fluid stays constant. For the case of ideal gas as working fluid and a given switching time, it is shown that maximum work is obtained at Curzon-Ahlborn efficiency. Our expressions clearly show the dependence on the relative magnitudes of heat capacities of the fluid and the reservoirs. Many previous formulae, including infinite reservoirs, infinite-time cycles, and Carnot-like and non-Carnot-like cycles, are recovered as special cases of our model.
Wijesekara, Waruna; Rosendahl, Lasse; Wu, NingYu;
Oxide thermoelectric materials are promising candidates for energy harvesting from mid to high temperature heat sources. In this work, the oxide thermoelectric materials and the final design of the high temperature thermoelectric module were developed. Also, prototypes of oxide thermoelectric...... generator were built for high temperature applications. This paper specifically discusses the thermoelectric module design and the prototype validations of the design. Here p type calcium cobalt oxide and n type aluminum doped ZnO were developed as the oxide thermoelectric materials. Hot side and cold side...... temperatures were used as 1100 K and 400 K respectively. Using analytical methods, the optimum thermoelement length and the thermoelements area ratio were explored in order to provide the maximum power output by the uni-couple and it is compared to methods reported in literature. Based on operating conditions...
Howell, L W
2002-01-01
The method of Maximum Likelihood (ML) is used to estimate the spectral parameters of an assumed broken power law energy spectrum from simulated detector responses. This methodology, which requires the complete specificity of all cosmic-ray detector design parameters, is shown to provide approximately unbiased, minimum variance, and normally distributed spectra information for events detected by an instrument having a wide range of commonly used detector response functions. The ML procedure, coupled with the simulated performance of a proposed space-based detector and its planned life cycle, has proved to be of significant value in the design phase of a new science instrument. The procedure helped make important trade studies in design parameters as a function of the science objectives, which is particularly important for space-based detectors where physical parameters, such as dimension and weight, impose rigorous practical limits to the design envelope. This ML methodology is then generalized to estimate bro...
Maximum power point tracking of a photovoltaic energy system using neural fuzzy techniques
LI Chun-hua; ZHU Xin-jian; SUI Sheng; HU Wan-qi
2009-01-01
In order to improve the output efficiency of a photovoltaic (PV) energy system, the real-time maximum power point (MPP) of the PV array should be tracked closely. The non-linear and time-variant characteristics of the photovoltaic array and the non-linear and non-minimum phase characteristics of a boost converter make it difficult to track the MPP as in traditional control strategies. A neural fuzzy controller (NFC) in conjunction with the reasoning capability of fuzzy logical systems and the learning capability of neural networks is proposed to track the MPP in this paper. A gradient estimator based on a radial basis function neural network is developed to provide the reference information to the NFC. With a derived learning algorithm, the parameters of the NFC are updated adaptively. Experimental results show that, compared with the fuzzy logic control algorithm, the proposed control algorithm provides much better tracking performance.
Man, E. A.; Sera, D.; Mathe, L.; Schaltz, E.; Rosendahl, L.
2016-03-01
Characterization of thermoelectric generators (TEG) is widely discussed and equipment has been built that can perform such analysis. One method is often used to perform such characterization: constant temperature with variable thermal power input. Maximum power point tracking (MPPT) methods for TEG systems are mostly tested under steady-state conditions for different constant input temperatures. However, for most TEG applications, the input temperature gradient changes, exposing the MPPT to variable tracking conditions. An example is the exhaust pipe on hybrid vehicles, for which, because of the intermittent operation of the internal combustion engine, the TEG and its MPPT controller are exposed to a cyclic temperature profile. Furthermore, there are no guidelines on how fast the MPPT must be under such dynamic conditions. In the work discussed in this paper, temperature gradients for TEG integrated in several applications were evaluated; the results showed temperature variation up to 5°C/s for TEG systems. Electrical characterization of a calcium-manganese oxide TEG was performed at steady-state for different input temperatures and a maximum temperature of 401°C. By using electrical data from characterization of the oxide module, a solar array simulator was emulated to perform as a TEG. A trapezoidal temperature profile with different gradients was used on the TEG simulator to evaluate the dynamic MPPT efficiency. It is known that the perturb and observe (P&O) algorithm may have difficulty accurately tracking under rapidly changing conditions. To solve this problem, a compromise must be found between the magnitude of the increment and the sampling frequency of the control algorithm. The standard P&O performance was evaluated experimentally by using different temperature gradients for different MPPT sampling frequencies, and efficiency values are provided for all cases. The results showed that a tracking speed of 2.5 Hz can be successfully implemented on a TEG
Fast calculation of the maximum power point of photovoltaic generators under partial shading
Carlos Andres Ramos-Paja
2016-09-01
Full Text Available This paper presents a method to calculate the energy production of photovoltaic generators considering partial shading or mismatched conditions. The proposed method is based on the complete one-diode model including the bypass diode in its exponential form, where the current and voltage values of the modules composing the photovoltaic panel array are calculated without using the Lambert-W function. In addition, the method introduces a procedure to calculate the vicinity of the maximum power points, which enables the reduction of the operations required to obtain the global maximum. The proposed method provides short simulation times and high accuracy. On the other hand, since the method does not require complex mathematical functions, it can be implemented straightforwardly on known software packages and development languages such as C and C++. Those characteristics make this method a useful tool to evaluate the economic viability and return-of-investment time of photovoltaic installations. Simulation results and comparisons with a classical procedure confirm the good performance of the proposed method in terms of execution time and accuracy.
2016-01-01
Photovoltaic (PV) systems have non-linear characteristics that generate maximum power at one particular operating point. Environmental factors such as irradiance and temperature variations greatly affect the maximum power point (MPP). Diverse offline and online techniques have been introduced for tracking the MPP. Here, to track the MPP, an augmented-state feedback linearized (AFL) non-linear controller combined with an artificial neural network (ANN) is proposed. This approach linearizes the...
Comparative Study of Maximum Power Point Tracking Techniques for Photovoltaic Systems
Fernando Lessa Tofoli
2015-01-01
Full Text Available The generation of electricity from photovoltaic (PV arrays has been increasingly considered as a prominent alternative to fossil fuels. However, the conversion efficiency is typically low and the initial cost is still appreciable. A required feature of a PV system is the ability to track the maximum power point (MPP of the PV array. Besides, MPP tracking (MPPT is desirable in both grid-connected and stand-alone photovoltaic systems because the solar irradiance and temperature change throughout the day, as well as along seasons and geographical conditions, also leading to the modification of the I×V (current versus voltage and P×V (power versus voltage curves of the PV module. MPPT is also justified by the relatively high cost of the energy generated by PV systems if compared with other sources. Since there are various MPPT approaches available in the literature, this work presents a comparative study among four popular techniques, which are the fixed duty cycle method, constant voltage (CV, perturb and observe (P&O, and incremental conductance (IC. It considers different operational climatic conditions (i.e., irradiance and temperature, since the MPP is nonlinear with the environment status. PSIM software is used to validate the assumptions, while relevant results are discussed in detail.
25(OHD3 Levels Relative to Muscle Strength and Maximum Oxygen Uptake in Athletes
Książek Anna
2016-04-01
Full Text Available Vitamin D is mainly known for its effects on the bone and calcium metabolism. The discovery of Vitamin D receptors in many extraskeletal cells suggests that it may also play a significant role in other organs and systems. The aim of our study was to assess the relationship between 25(OHD3 levels, lower limb isokinetic strength and maximum oxygen uptake in well-trained professional football players. We enrolled 43 Polish premier league soccer players. The mean age was 22.7±5.3 years. Our study showed decreased serum 25(OHD3 levels in 74.4% of the professional players. The results also demonstrated a lack of statistically significant correlation between 25(OHD3 levels and lower limb muscle strength with the exception of peak torque of the left knee extensors at an angular velocity of 150°/s (r=0.41. No significant correlations were found between hand grip strength and maximum oxygen uptake. Based on our study we concluded that in well-trained professional soccer players, there was no correlation between serum levels of 25(OHD3 and muscle strength or maximum oxygen uptake.
Senjyu, Tomonobu; Ochi, Yasutaka; Kikunaga, Yasuaki; Tokudome, Motoki; Yona, Atsushi; Muhando, Endusa Billy; Urasaki, Naomitsu [Department of Electrical and Electronics Engineering, Faculty of Engineering, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami, Okinawa 903-0213 (Japan); Funabashi, Toshihisa [Meidensha Corporation, ThinkPark Tower, 2-1-1, Ohsaki, Shinagawa-ku, Tokyo 141-6029 (Japan)
2009-04-15
This paper proposes a technique that determines the optimal windmill operation speed and the optimal rotor flux. Moreover, the position and speed sensor-less wind generation system using the electromotive voltage observer to estimate rotor position and full-order observer to estimate rotor speed and the windmill output torque are proposed. The position and speed sensor-less maximum power point of wind power generation system is controlled by using the above estimated values, optimized windmill operation speed for maximum output power and optimized rotor flux for minimum generator losses. The effectiveness of the position and speed sensor-less maximum power point tracking control for wind power generation system with squirrel cage induction generator is verified by simulations. The simulation results confirm that the proposed method can estimate the operation speed efficiently. (author)
Yudong Zhang
2011-04-01
Full Text Available This paper proposes a global multi-level thresholding method for image segmentation. As a criterion for this, the traditional method uses the Shannon entropy, originated from information theory, considering the gray level image histogram as a probability distribution, while we applied the Tsallis entropy as a general information theory entropy formalism. For the algorithm, we used the artificial bee colony approach since execution of an exhaustive algorithm would be too time-consuming. The experiments demonstrate that: 1 the Tsallis entropy is superior to traditional maximum entropy thresholding, maximum between class variance thresholding, and minimum cross entropy thresholding; 2 the artificial bee colony is more rapid than either genetic algorithm or particle swarm optimization. Therefore, our approach is effective and rapid.
Selective preparation of the maximum coherent superposition state in four-level atoms
Li Deng; Yueping Niu; Shangqing Gong
2011-01-01
We demonstrate that the maximum coherent superposition state can be selectively prepared using a sequence of pulse pairs in lambda-type atomic systems, with the final level as a doublet. In each pair, the Stocks pulse comes before the pump pulse, with their back edges overlapping. Numerical results indicate that by tuning the interval of the adjacent pulse pairs, the selective maximum coherent superposition state preparation between the initial and one of the final levels can be achieved. The phenomenon is caused by the accumulative property of the pulse sequence.%The coherent superposition state in atoms or molecules plays a crucial role in quantum physics.It has applications in many areas such as electromagnetically induced transparency[1-5],quantum information[6-8] and control of chemical reaction[9-11].Many schemes can prepare the coherent superposition state.For instance,the fractional stimulated Raman adiabatic passage(F-STIRAP) [12] and the coherent population trapping[13] can obtain the maximum coherent superposition state of the two lower levels in lambda-type atoms.Our group also proposed several schemes to achieve this goal,such as the methods based on the STIRAP[14,15] and the pulse train method[16].
Quantum Coherent Three-Terminal Thermoelectrics: Maximum Efficiency at Given Power Output
Robert S. Whitney
2016-05-01
Full Text Available This work considers the nonlinear scattering theory for three-terminal thermoelectric devices used for power generation or refrigeration. Such systems are quantum phase-coherent versions of a thermocouple, and the theory applies to systems in which interactions can be treated at a mean-field level. It considers an arbitrary three-terminal system in any external magnetic field, including systems with broken time-reversal symmetry, such as chiral thermoelectrics, as well as systems in which the magnetic field plays no role. It is shown that the upper bound on efficiency at given power output is of quantum origin and is stricter than Carnot’s bound. The bound is exactly the same as previously found for two-terminal devices and can be achieved by three-terminal systems with or without broken time-reversal symmetry, i.e., chiral and non-chiral thermoelectrics.
Low Power Design with High-Level Power Estimation and Power-Aware Synthesis
Ahuja, Sumit; Shukla, Sandeep Kumar
2012-01-01
Low-power ASIC/FPGA based designs are important due to the need for extended battery life, reduced form factor, and lower packaging and cooling costs for electronic devices. These products require fast turnaround time because of the increasing demand for handheld electronic devices such as cell-phones, PDAs and high performance machines for data centers. To achieve short time to market, design flows must facilitate a much shortened time-to-product requirement. High-level modeling, architectural exploration and direct synthesis of design from high level description enable this design process. This book presents novel research techniques, algorithms,methodologies and experimental results for high level power estimation and power aware high-level synthesis. Readers will learn to apply such techniques to enable design flows resulting in shorter time to market and successful low power ASIC/FPGA design. Integrates power estimation and reduction for high level synthesis, with low-power, high-level design; Shows spec...
Santos-Silva, Paulo Roberto; Fonseca, Alfredo José; Castro, Anita Weigand de; Greve, Júlia Maria D'Andréa; Hernandez, Arnaldo José
2007-08-01
To determine the degree of reproducibility of maximum oxygen consumption (VO2max) among soccer players, using a modified Heck protocol. 2 evaluations with an interval of 15 days between them were performed on 11 male soccer players. All the players were at a high performance level; they were training for an average of 10 hours per week, totaling 5 times a week. When they were evaluated, they were in the middle of the competitive season, playing 1 match per week. The soccer players were evaluated on an ergometric treadmill with velocity increments of 1.2 km.h-1 every 2 minutes and a fixed inclination of 3% during the test. VO2max was measured directly using a breath-by-breath metabolic gas analyzer. The maximum running speed and VO2max attained in the 2 tests were, respectively: (15.6 +/- 1.1 vs. 15.7 +/- 1.2 km.h-1; [P = .78]) and (54.5 +/- 3.9 vs. 55.2 +/- 4.4 ml.kg-1.min-1; [P = .88]). There was high and significant correlation of VO2max between the 2 tests with a 15-day interval between them [r = 0.97; P testing was insufficient to significantly modify the soccer players' VO2max values.
Subiyanto
2013-01-01
Full Text Available Photovoltaic (PV system is one of the promising renewable energy technologies. Although the energy conversion efficiency of the system is still low, but it has the advantage that the operating cost is free, very low maintenance and pollution-free. Maximum power point tracking (MPPT is a significant part of PV systems. This paper presents a novel intelligent MPPT controller for PV systems. For the MPPT algorithm, an optimized fuzzy logic controller (FLC using the Hopfield neural network is proposed. It utilizes an automatically tuned FLC membership function instead of the trial-and-error approach. The MPPT algorithm is implemented in a new variant of coupled inductor soft switching boost converter with high voltage gain to increase the converter output from the PV panel. The applied switching technique, which includes passive and active regenerative snubber circuits, reduces the insulated gate bipolar transistor switching losses. The proposed MPPT algorithm is implemented using the dSPACE DS1104 platform software on a DS1104 board controller. The prototype MPPT controller is tested using an agilent solar array simulator together with a 3 kW real PV panel. Experimental test results show that the proposed boost converter produces higher output voltages and gives better efficiency (90% than the conventional boost converter with an RCD snubber, which gives 81% efficiency. The prototype MPPT controller is also found to be capable of tracking power from the 3 kW PV array about 2.4 times more than that without using the MPPT controller.
Chao, R.M.; Ko, S.H.; Lin, I.H. [Department of Systems and Naval Mechatronics Engineering, National Cheng Kung University, Tainan, Taiwan 701 (China); Pai, F.S. [Department of Electronic Engineering, National University of Tainan (China); Chang, C.C. [Department of Environment and Energy, National University of Tainan (China)
2009-12-15
The historically high cost of crude oil price is stimulating research into solar (green) energy as an alternative energy source. In general, applications with large solar energy output require a maximum power point tracking (MPPT) algorithm to optimize the power generated by the photovoltaic effect. This work aims to provide a stand-alone solution for solar energy applications by integrating a DC/DC buck converter to a newly developed quadratic MPPT algorithm along with its appropriate software and hardware. The quadratic MPPT method utilizes three previously used duty cycles with their corresponding power outputs. It approaches the maximum value by using a second order polynomial formula, which converges faster than the existing MPPT algorithm. The hardware implementation takes advantage of the real-time controller system from National Instruments, USA. Experimental results have shown that the proposed solar mechatronics system can correctly and effectively track the maximum power point without any difficulties. (author)
Bayu Prima Juliansyah Putra
2013-09-01
Full Text Available Salah satu aplikasi yang sering digunakan dalam bidang energi terbarukan adalah panel photovoltaic. Panel ini memiliki prinsip kerja berdasarkan efek photovoltaic dimana lempengan logam akan menghasilkan energi listrik apabila diberi intensitas cahaya. Untuk menghasilkan daya keluaran panel yang maksimal, maka diperlukan suatu algoritma yang biasa disebut Maximum Power Point Tracking (MPPT.MPPT yang diterapkan pada sistem photovoltaic berfungsi untuk mengatur nilai tegangan keluaran panel sehingga titik ker-janya beroperasi pada kondisi maksimal. Algoritma MPPT pada panel ini telah dilakukan dengan menggunakan logika fuzzy melalui mikrokontroler Arduino Uno sebagai pem-bangkit sinyal Pulse Width Modulation (PWM yang akan dikirimkan menuju DC-DC Buck Boost Converter. Keluaran dari buck boost converterakan dihubungkan secara langsung dengan buoy weather station untuk menyuplai energi listrik tiap komponen yang berada di dalamnya. Untuk menguji performansi dari algoritma MPPT yang telah dirancang, maka sistem akan diuji menggunakan variasi beban antara metode direct-coupled dengan MPPT menggunakan logika fuzzy. Hasil pengujian menunjukkan bahwa MPPT dengan logika fuzzy dapat menghasilkan daya maksimum daripada direct-coupled. Pada sistem panel photovoltaic ini memiliki range efisiensi 33.07589 % hingga 74.25743 %. Daya mak-simal dapat dicapai oleh sistem untuk tiap variasi beban dan efisiensi maksimal dapat dicapai pada beban 20 Ohm dari hasil pengujian sistem MPPT.
IMPLEMENTATION OF FUZZY LOGIC MAXIMUM POWER POINT TRACKING CONTROLLER FOR PHOTOVOLTAIC SYSTEM
Rasoul Rahmani
2013-01-01
Full Text Available In this study, simulation and hardware implementation of Fuzzy Logic (FL Maximum Power Point Tracking (MPPT used in photovoltaic system with a direct control method are presented. In this control system, no proportional or integral control loop exists and an adaptive FL controller generates the control signals. The designed and integrated system is a contribution of different aspects which includes simulation, design and programming and experimental setup. The resultant system is capable and satisfactory in terms of fastness and dynamic performance. The results also indicate that the control system works without steady-state error and has the ability of tracking MPPs rapid and accurate which is useful for the sudden changes in the atmospheric condition. MATLAB/Simulink software is utilized for simulation and also programming the TMS320F2812 Digital Signal Processor (DSP. The whole system designed and implemented to hardware was tested successfully on a laboratory PV array. The obtained experimental results show the functionality and feasibility of the proposed controller.
Thermodynamics, maximum power, and the dynamics of preferential river flow structures on continents
A. Kleidon
2012-06-01
Full Text Available The organization of drainage basins shows some reproducible phenomena, as exemplified by self-similar fractal river network structures and typical scaling laws, and these have been related to energetic optimization principles, such as minimization of stream power, minimum energy expenditure or maximum "access". Here we describe the organization and dynamics of drainage systems using thermodynamics, focusing on the generation, dissipation and transfer of free energy associated with river flow and sediment transport. We argue that the organization of drainage basins reflects the fundamental tendency of natural systems to deplete driving gradients as fast as possible through the maximization of free energy generation, thereby accelerating the dynamics of the system. This effectively results in the maximization of sediment export to deplete topographic gradients as fast as possible and potentially involves large-scale feedbacks to continental uplift. We illustrate this thermodynamic description with a set of three highly simplified models related to water and sediment flow and describe the mechanisms and feedbacks involved in the evolution and dynamics of the associated structures. We close by discussing how this thermodynamic perspective is consistent with previous approaches and the implications that such a thermodynamic description has for the understanding and prediction of sub-grid scale organization of drainage systems and preferential flow structures in general.
A. Kleidon
2013-01-01
Full Text Available The organization of drainage basins shows some reproducible phenomena, as exemplified by self-similar fractal river network structures and typical scaling laws, and these have been related to energetic optimization principles, such as minimization of stream power, minimum energy expenditure or maximum "access". Here we describe the organization and dynamics of drainage systems using thermodynamics, focusing on the generation, dissipation and transfer of free energy associated with river flow and sediment transport. We argue that the organization of drainage basins reflects the fundamental tendency of natural systems to deplete driving gradients as fast as possible through the maximization of free energy generation, thereby accelerating the dynamics of the system. This effectively results in the maximization of sediment export to deplete topographic gradients as fast as possible and potentially involves large-scale feedbacks to continental uplift. We illustrate this thermodynamic description with a set of three highly simplified models related to water and sediment flow and describe the mechanisms and feedbacks involved in the evolution and dynamics of the associated structures. We close by discussing how this thermodynamic perspective is consistent with previous approaches and the implications that such a thermodynamic description has for the understanding and prediction of sub-grid scale organization of drainage systems and preferential flow structures in general.
Efficiency at maximum power output for an engine with a passive piston
Sano, Tomohiko G.; Hayakawa, Hisao
2016-08-01
Efficiency at maximum power (MP) output for an engine with a passive piston without mechanical controls between two reservoirs is studied theoretically. We enclose a hard core gas partitioned by a massive piston in a temperature-controlled container and analyze the efficiency at MP under a heating and cooling protocol without controlling the pressure acting on the piston from outside. We find the following three results: (i) The efficiency at MP for a dilute gas is close to the Chambadal-Novikov-Curzon-Ahlborn (CNCA) efficiency if we can ignore the sidewall friction and the loss of energy between a gas particle and the piston, while (ii) the efficiency for a moderately dense gas becomes smaller than the CNCA efficiency even when the temperature difference of the reservoirs is small. (iii) Introducing the Onsager matrix for an engine with a passive piston, we verify that the tight coupling condition for the matrix of the dilute gas is satisfied, while that of the moderately dense gas is not satisfied because of the inevitable heat leak. We confirm the validity of these results using the molecular dynamics simulation and introducing an effective mean-field-like model which we call the stochastic mean field model.
Optimized Large-Scale CMB Likelihood And Quadratic Maximum Likelihood Power Spectrum Estimation
Gjerløw, E; Eriksen, H K; Górski, K M; Gruppuso, A; Jewell, J B; Plaszczynski, S; Wehus, I K
2015-01-01
We revisit the problem of exact CMB likelihood and power spectrum estimation with the goal of minimizing computational cost through linear compression. This idea was originally proposed for CMB purposes by Tegmark et al.\\ (1997), and here we develop it into a fully working computational framework for large-scale polarization analysis, adopting \\WMAP\\ as a worked example. We compare five different linear bases (pixel space, harmonic space, noise covariance eigenvectors, signal-to-noise covariance eigenvectors and signal-plus-noise covariance eigenvectors) in terms of compression efficiency, and find that the computationally most efficient basis is the signal-to-noise eigenvector basis, which is closely related to the Karhunen-Loeve and Principal Component transforms, in agreement with previous suggestions. For this basis, the information in 6836 unmasked \\WMAP\\ sky map pixels can be compressed into a smaller set of 3102 modes, with a maximum error increase of any single multipole of 3.8\\% at $\\ell\\le32$, and a...
Gonzalez, L.G. [Departamento de Electronica y Comunicaciones, Universidad de los Andes, nucleo la Hechicera, 5101 Merida (Venezuela); Figueres, E.; Garcera, G. [Grupo de Sistemas Electronicos Industriales, Universidad Politecnica de Valencia, Camino de vera s/n, 46022 Valencia (Spain); Carranza, O. [Escuela Superior de Computo, Instituto Politecnico Nacional, Av. Juan de Dios Batiz s/n, 07738 DF (Mexico)
2010-07-15
This paper presents an improved maximum-power-point tracking algorithm for wind-energy-conversion-systems. The proposed method significantly reduces the turbine mechanical stress with regard to conventional techniques, so that both the maintenance needs and the medium time between failures are expected to be improved. To achieve these objectives, a sensorless speed control loop receives its reference signal from a modified Perturb and Observe algorithm, in which the typical steps on the reference speed have been substituted by a fixed and well-defined slope ramp signal. As a result, it is achieved a soft dynamic response of both the torque and the speed of the wind turbine, so that the whole system suffers from a lower mechanical stress than with conventional P and O techniques. The proposed method has been applied to a wind turbine based on a permanent magnet synchronous generator operating at variable speed, which is connected to the distribution grid by means of a back to back converter. (author)
Efficiency at maximum power and efficiency fluctuations in a linear Brownian heat-engine model
Park, Jong-Min; Chun, Hyun-Myung; Noh, Jae Dong
2016-07-01
We investigate the stochastic thermodynamics of a two-particle Langevin system. Each particle is in contact with a heat bath at different temperatures T1 and T2 (autonomous heat engine performing work against the external driving force. Linearity of the system enables us to examine thermodynamic properties of the engine analytically. We find that the efficiency of the engine at maximum power ηM P is given by ηM P=1 -√{T2/T1 } . This universal form has been known as a characteristic of endoreversible heat engines. Our result extends the universal behavior of ηM P to nonendoreversible engines. We also obtain the large deviation function of the probability distribution for the stochastic efficiency in the overdamped limit. The large deviation function takes the minimum value at macroscopic efficiency η =η ¯ and increases monotonically until it reaches plateaus when η ≤ηL and η ≥ηR with model-dependent parameters ηR and ηL.
Cui, Wenchao; Wang, Yi; Lei, Tao; Fan, Yangyu; Feng, Yan
2013-01-01
This paper presents a variational level set method for simultaneous segmentation and bias field estimation of medical images with intensity inhomogeneity. In our model, the statistics of image intensities belonging to each different tissue in local regions are characterized by Gaussian distributions with different means and variances. According to maximum a posteriori probability (MAP) and Bayes' rule, we first derive a local objective function for image intensities in a neighborhood around each pixel. Then this local objective function is integrated with respect to the neighborhood center over the entire image domain to give a global criterion. In level set framework, this global criterion defines an energy in terms of the level set functions that represent a partition of the image domain and a bias field that accounts for the intensity inhomogeneity of the image. Therefore, image segmentation and bias field estimation are simultaneously achieved via a level set evolution process. Experimental results for synthetic and real images show desirable performances of our method.
Maximum Efficiency of Thermoelectric Heat Conversion in High-Temperature Power Devices
V. I. Khvesyuk
2016-01-01
Full Text Available Modern trends in development of aircraft engineering go with development of vehicles of the fifth generation. The features of aircrafts of the fifth generation are motivation to use new high-performance systems of onboard power supply. The operating temperature of the outer walls of engines is of 800–1000 K. This corresponds to radiation heat flux of 10 kW/m2 . The thermal energy including radiation of the engine wall may potentially be converted into electricity. The main objective of this paper is to analyze if it is possible to use a high efficiency thermoelectric conversion of heat into electricity. The paper considers issues such as working processes, choice of materials, and optimization of thermoelectric conversion. It presents the analysis results of operating conditions of thermoelectric generator (TEG used in advanced hightemperature power devices. A high-temperature heat source is a favorable factor for the thermoelectric conversion of heat. It is shown that for existing thermoelectric materials a theoretical conversion efficiency can reach the level of 15–20% at temperatures up to 1500 K and available values of Ioffe parameter being ZT = 2–3 (Z is figure of merit, T is temperature. To ensure temperature regime and high efficiency thermoelectric conversion simultaneously it is necessary to have a certain match between TEG power, temperature of hot and cold surfaces, and heat transfer coefficient of the cooling system. The paper discusses a concept of radiation absorber on the TEG hot surface. The analysis has demonstrated a number of potentialities for highly efficient conversion through using the TEG in high-temperature power devices. This work has been implemented under support of the Ministry of Education and Science of the Russian Federation; project No. 1145 (the programme “Organization of Research Engineering Activities”.
2012-04-03
... supply. The FAS underlies approximately 100,000 square miles (258,000 km\\2\\) in southern Alabama..., crustaceans, fish, sea turtles, and marine mammals. The portion of Biscayne Bay adjacent to Turkey Point is... smallii tiny polygala E Insects Heraclides aristodemus schaus swallowtail E ponceanus. butterfly....
Optimal Velocity to Achieve Maximum Power Output – Bench Press for Trained Footballers
Richard Billich
2015-03-01
Full Text Available Optimal Velocity to Achieve Maximum Power Output – Bench Press for Trained Footballers In today’s world of strength training there are many myths surrounding effective exercising with the least possible negative effect on one’s health. In this experiment we focus on the finding of a relationship between maximum output, used load and the velocity with which the exercise is performed. The main objective is to find the optimal speed of the exercise motion which would allow us to reach the maximum mechanic muscle output during a bench press exercise. This information could be beneficial to sporting coaches and recreational sportsmen alike in helping them improve the effectiveness of fast strength training. Fifteen football players of the FK Třinec football club participated in the experiment. The measurements were made with the use of 3D cinematic and dynamic analysis, both experimental methods. The research subjects participated in a strength test, in which the mechanic muscle output of 0, 10, 30, 50, 70, 90% and one repetition maximum (1RM was measured. The acquired result values and other required data were modified using Qualisys Track Manager and Visual 3D software (C-motion, Rockville, MD, USA. During the bench press exercise the maximum mechanic muscle output of the set of research subjects was reached at 75% of maximum exercise motion velocity. Optimální rychlost pohybu pro dosažení maxima výstupního výkonu – bench press u trénovaných fotbalistů Dnešní svět silového tréninku přináší řadu mýtů o tom, jak cvičit efektivně a zároveň s co nejmenším negativním vlivem na zdraví člověka. V tomto experimentu se zabýváme nalezením vztahu mezi maximálním výkonem, použitou zátěží a rychlostí. Hlavním úkolem je nalezení optimální rychlosti pohybu pro dosažení maximálního mechanického svalového výkonu při cvičení bench press, což pomůže nejenom trenérům, ale i rekreačním sportovc
A New Fuzzy-Based Maximum Power Point Tracker for a Solar Panel Based on Datasheet Values
Ali Kargarnejad
2013-01-01
Full Text Available Tracking maximum power point of a solar panel is of interest in most of photovoltaic applications. Solar panel modeling is also very interesting exclusively based on manufacturers data. Knowing that the manufacturers generally give the electrical specifications of their products at one operating condition, there are so many cases in which the specifications in other conditions are of interest. In this research, a comprehensive one-diode model for a solar panel with maximum obtainable accuracy is fully developed only based on datasheet values. The model parameters dependencies on environmental conditions are taken into consideration as much as possible. Comparison between real data and simulations results shows that the proposed model has maximum obtainable accuracy. Then a new fuzzy-based controller to track the maximum power point of the solar panel is also proposed which has better response from speed, accuracy and stability point of view respect to the previous common developed one.
N Clark
2003-03-01
Full Text Available The aim of this study was to investigate maximum aerobic power (VO2 max and anaerobic threshold (AT as determinants of training status among professional soccer players. Twelve professional 1st team British male soccer players (age: 26.2 ± 3.3 years, height: 1.77 ± 0.05 m, body mass: 79.3 ± 9.4 kg agreed to participate in the study and provided informed consent. All subjects completed a combined test of anaerobic threshold (AT and maximum aerobic power on two occasions: Test 1 following 5 weeks of low level activity at the end of the off-season and Test 2 immediately following conclusion of the competitive season. AT was assessed as both lactate threshold (LT and ventilatory threshold (VT. There was no change in VO2 max between Test 1 and Test 2 (63.3 ± 5.8 ml·kg-1·min-1 vs. 62.1 ± 4.9 ml·kg-1·min-1 respectively, however, the duration of exercise tolerance (ET at VO2 max was significantly extended from Test 1 to Test 2 (204 ± 54 vs. 228 ± 68 s respectively (P<0.01. LT oxygen consumption was significantly improved in Test 2 versus Test 1 (P<0.01 VT was also improved (P<0.05. There was no significant difference in VO2 (ml·kg-1·min-1 corresponding to LT and VT. The results of this study show that VO2 max is a less sensitive indicator to changes in training status in professional soccer players than either LT or VT.
Park, Jungyong; Kim, Shiho
2012-06-01
An analog maximum power point tracking (MPPT) circuit for a thermoelectric generator (TEG) is proposed. We show that the peak point of the voltage conversion gain of a boost DC-DC converter with an input voltage source having an internal resistor is the maximum power point of the TEG. The key characteristic of the proposed MPPT controller is that the duty ratio of the input clock pulse to the boost DC-DC converter shifts toward the maximum power point of the TEG by seeking the peak gain point of the boost DC-DC converters. The proposed MPPT technique provides a simple and useful analog MPPT solution, without employing digital microcontroller units.
A New Fuzzy-Based Maximum Power Point Tracker for a Solar Panel Based on Datasheet Values
Ali Kargarnejad; Mohsen Taherbaneh; Amir Hosein Kashefi
2013-01-01
Tracking maximum power point of a solar panel is of interest in most of photovoltaic applications. Solar panel modeling is also very interesting exclusively based on manufacturers data. Knowing that the manufacturers generally give the electrical specifications of their products at one operating condition, there are so many cases in which the specifications in other conditions are of interest. In this research, a comprehensive one-diode model for a solar panel with maximum obtainable accuracy...
Ahteshamul Haque
2016-02-01
Full Text Available The energy crisis concern leads to look for alternate source of energy. Solar energy is considered as most reliable among the all renewable energy sources. Solar PV (Photovoltaic is used to convert solar energy into electric energy. The efficiency of solar PV is very low and its characteristic is nonlinear. To overcome these drawbacks a technique known as maximum power point tracking is used. This algorithm is implemented in the control circuit of DC – DC converter. The objective of this paper is to evaluate the MPPT (Maximum Power Point Tracking with buck DC-DC converter under load varying conditions. The simulation work is done using PSIM simulation software.
Maria Pilar Martínez Ruiz
2010-12-01
Full Text Available From the initial consideration of the store attributes that the marketing literature has identified as key in order that grocery retailers manage to design their differentiation strategies, this work identifies the main factors underlying the above mentioned attributes. The goal is to analyze which of these factors exert a bigger influence on the highest level of customer satisfaction. With this intention, we have examined a sample of 422 consumers who had carried out their purchase in different types of store formats in Spain, considering the influence of feature advertising on the clientele behavior. Interesting conclusions related to the aspects that most impact on the maximum level of customer satisfaction depending on the influence of feature advertising stem from this work.
The Betz-Joukowsky limit for the maximum power coefficient of wind turbines
Okulov, Valery; van Kuik, G.A.M.
2009-01-01
The article addresses to a history of an important scientific result in wind energy. The maximum efficiency of an ideal wind turbine rotor is well known as the ‘Betz limit’, named after the German scientist that formulated this maximum in 1920. Also Lanchester, a British scientist, is associated...
Wang, Kezhi
2014-10-01
Bit error rate (BER) and outage probability for amplify-and-forward (AF) relaying systems with two different channel estimation methods, disintegrated channel estimation and cascaded channel estimation, using pilot-aided maximum likelihood method in slowly fading Rayleigh channels are derived. Based on the BERs, the optimal values of pilot power under the total transmitting power constraints at the source and the optimal values of pilot power under the total transmitting power constraints at the relay are obtained, separately. Moreover, the optimal power allocation between the pilot power at the source, the pilot power at the relay, the data power at the source and the data power at the relay are obtained when their total transmitting power is fixed. Numerical results show that the derived BER expressions match with the simulation results. They also show that the proposed systems with optimal power allocation outperform the conventional systems without power allocation under the same other conditions. In some cases, the gain could be as large as several dB\\'s in effective signal-to-noise ratio.
Maheshwari, Govind; Chaudhary, S; Somani, S.K
2010-01-01
The efficient power, defined as the product of power output and efficiency of the engine, is taken as the objective for performance analysis and optimization of an endoreversible combined Carnot heat...
DONG Sheng; CHI Kun; ZHANG Qiyi; ZHANG Xiangdong
2012-01-01
Compared with traditional real-time forecasting,this paper proposes a Grey Markov Model (GMM) to forecast the maximum water levels at hydrological stations in the estuary area.The GMM combines the Grey System and Markov theory into a higher precision model.The GMM takes advantage of the Grey System to predict the trend values and uses the Markov theory to forecast fluctuation values,and thus gives forecast results involving two aspects of information.The procedure for forecasting annul maximum water levels with the GMM contains five main steps:1) establish the GM (1,1) model based on the data series; 2) estimate the trend values; 3) establish a Markov Model based on relative error series; 4) modify the relative errors caused in step 2,and then obtain the relative errors of the second order estimation; 5) compare the results with measured data and estimate the accuracy.The historical water level records (from 1960 to 1992) at Yuqiao Hydrological Station in the estuary area of the Haihe River near Tianjin,China are utilized to calibrate and verify the proposed model according to the above steps.Every 25 years' data are regarded as a hydro-sequence.Eight groups of simulated results show reasonable agreement between the predicted values and the measured data.The GMM is also applied to the 10 other hydrological stations in the same estuary.The forecast results for all of the hydrological stations are good or acceptable.The feasibility and effectiveness of this new forecasting model have been proved in this paper.
Nimmrichter, P.; McClintock, J.; Peng, J. [AMEC plc., Toronto, ON (Canada); Leung, H. [Nuclear Waste Management Organization, Toronto, ON (Canada)
2011-07-01
Ontario Power Generation (OPG) has entered a process to seek Environmental Assessment and licensing approvals to construct a Deep Geologic Repository (DGR) for Low and Intermediate Level Radioactive Waste (L&ILW) near the existing Western Waste Management Facility (WWMF) at the Bruce nuclear site in the Municipality of Kincardine, Ontario. In support of the design of the proposed DGR project, maximum flood stages were estimated for potential flood hazard risks associated with coastal, riverine and direct precipitation flooding. The estimation of lake/coastal flooding for the Bruce nuclear site considered potential extreme water levels in Lake Huron, storm surge and seiche, wind waves, and tsunamis. The riverine flood hazard assessment considered the Probable Maximum Flood (PMF) within the local watersheds, and within local drainage areas that will be directly impacted by the site development. A series of hydraulic models were developed, based on DGR project site grading and ditching, to assess the impact of a Probable Maximum Precipitation (PMP) occurring directly at the DGR site. Overall, this flood assessment concluded there is no potential for lake or riverine based flooding and the DGR area is not affected by tsunamis. However, it was also concluded from the results of this analysis that the PMF in proximity to the critical DGR operational areas and infrastructure would be higher than the proposed elevation of the entrance to the underground works. This paper provides an overview of the assessment of potential flood hazard risks associated with coastal, riverine and direct precipitation flooding that was completed for the DGR development. (author)
Wenchao Cui
2013-01-01
Full Text Available This paper presents a variational level set method for simultaneous segmentation and bias field estimation of medical images with intensity inhomogeneity. In our model, the statistics of image intensities belonging to each different tissue in local regions are characterized by Gaussian distributions with different means and variances. According to maximum a posteriori probability (MAP and Bayes’ rule, we first derive a local objective function for image intensities in a neighborhood around each pixel. Then this local objective function is integrated with respect to the neighborhood center over the entire image domain to give a global criterion. In level set framework, this global criterion defines an energy in terms of the level set functions that represent a partition of the image domain and a bias field that accounts for the intensity inhomogeneity of the image. Therefore, image segmentation and bias field estimation are simultaneously achieved via a level set evolution process. Experimental results for synthetic and real images show desirable performances of our method.
Disproportionate Allocation of Indirect Costs at Individual-Farm Level Using Maximum Entropy
Markus Lips
2017-08-01
Full Text Available This paper addresses the allocation of indirect or joint costs among farm enterprises, and elaborates two maximum entropy models, the basic CoreModel and the InequalityModel, which additionally includes inequality restrictions in order to incorporate knowledge from production technology. Representing the indirect costing approach, both models address the individual-farm level and use standard costs from farm-management literature as allocation bases. They provide a disproportionate allocation, with the distinctive feature that enterprises with large allocation bases face stronger adjustments than enterprises with small ones, approximating indirect costing with reality. Based on crop-farm observations from the Swiss Farm Accountancy Data Network (FADN, including up to 36 observations per enterprise, both models are compared with a proportional allocation as reference base. The mean differences of the enterprise’s allocated labour inputs and machinery costs are in a range of up to ±35% and ±20% for the CoreModel and InequalityModel, respectively. We conclude that the choice of allocation methods has a strong influence on the resulting indirect costs. Furthermore, the application of inequality restrictions is a precondition to make the merits of the maximum entropy principle accessible for the allocation of indirect costs.
Sheng, Shiqi; Tu, Z C
2015-02-01
We present a unified perspective on nonequilibrium heat engines by generalizing nonlinear irreversible thermodynamics. For tight-coupling heat engines, a generic constitutive relation for nonlinear response accurate up to the quadratic order is derived from the stalling condition and the symmetry argument. By applying this generic nonlinear constitutive relation to finite-time thermodynamics, we obtain the necessary and sufficient condition for the universality of efficiency at maximum power, which states that a tight-coupling heat engine takes the universal efficiency at maximum power up to the quadratic order if and only if either the engine symmetrically interacts with two heat reservoirs or the elementary thermal energy flowing through the engine matches the characteristic energy of the engine. Hence we solve the following paradox: On the one hand, the quadratic term in the universal efficiency at maximum power for tight-coupling heat engines turned out to be a consequence of symmetry [Esposito, Lindenberg, and Van den Broeck, Phys. Rev. Lett. 102, 130602 (2009); Sheng and Tu, Phys. Rev. E 89, 012129 (2014)]; On the other hand, typical heat engines such as the Curzon-Ahlborn endoreversible heat engine [Curzon and Ahlborn, Am. J. Phys. 43, 22 (1975)] and the Feynman ratchet [Tu, J. Phys. A 41, 312003 (2008)] recover the universal efficiency at maximum power regardless of any symmetry.
Mihajlo Firak
2010-01-01
Full Text Available In order to combine a photovoltaic module and an electrolyzer to produce hydrogen from water, an intermediate DC/DC converter can be used to adapt output power features of the module to input power features of the electrolyzer. This can also be done without using electronics, which results in saving as much as 700 USD/kW, as previous investigation has shown. A more sophisticated investigation should be carried out with the aim of improving high system efficiency, resulting in matching the photovoltaic module maximum power point trajectory (the maximum power point path in the U-I plane as a result of solar irradiance change to the operating characteristic of the electrolyzer. This paper presents an analysis of the influences of photovoltaic module electric properties, such as series and parallel resistance and non-ideality factor, on the maximum power point trajectory at different levels of solar irradiance. The possibility of various inclinations (right - vertical - left in relation to an arbitrary chosen operating characteristic of the electrolyzer is also demonstrated. Simulated results are obtained by using Matlab/Simulink simulations of the well known one-diode model. Simulations have been confirmed with experiments on a real photovoltaic module where solar irradiance, solar cell temperature, electric current, and voltage in the circuit with variable ohmic resistance have been measured.
Jafarizadeh, M A; Sabric, H; Malekic, B Rashidian
2011-01-01
In this paper,a systematic study of quantum phase transition within U(5) \\leftrightarrow SO(6) limits is presented in terms of infinite dimensional Algebraic technique in the IBM framework. Energy level statistics are investigated with Maximum Likelihood Estimation (MLE) method in order to characterize transitional region. Eigenvalues of these systems are obtained by solving Bethe-Ansatz equations with least square fitting processes to experimental data to obtain constants of Hamiltonian. Our obtained results verify the dependence of Nearest Neighbor Spacing Distribution's (NNSD) parameter to control parameter (c_{s}) and also display chaotic behavior of transitional regions in comparing with both limits. In order to compare our results for two limits with both GUE and GOE ensembles, we have suggested a new NNSD distribution and have obtained better KLD distances for the new distribution in compared with others in both limits. Also in the case of N\\to\\infty, the total boson number dependence displays the univ...
Koutroulis, Eftichios; Blaabjerg, Frede
2012-01-01
output, such that it behaves as a constant input-power load. The proposed method has the advantage that it can be applied in either stand-alone or grid-connected PV systems comprising PV arrays with unknown electrical characteristics and does not require knowledge about the PV modules configuration......The power-voltage characteristic of photovoltaic (PV) arrays operating under partial-shading conditions exhibits multiple local maximum power points (MPPs). In this paper, a new method to track the global MPP is presented, which is based on controlling a dc/dc converter connected at the PV array...
Kimble, Michael C.; White, Ralph E.
1991-01-01
A mathematical model of a hydrogen/oxygen alkaline fuel cell is presented that can be used to predict the polarization behavior under various power loads. The major limitations to achieving high power densities are indicated and methods to increase the maximum attainable power density are suggested. The alkaline fuel cell model describes the phenomena occurring in the solid, liquid, and gaseous phases of the anode, separator, and cathode regions based on porous electrode theory applied to three phases. Fundamental equations of chemical engineering that describe conservation of mass and charge, species transport, and kinetic phenomena are used to develop the model by treating all phases as a homogeneous continuum.
Berna, C.; Escriva, A.; Munoz-Cobo, J. L.; Posada, J. M.
2014-07-01
The work consists in the simulation of code TRACE v5.0 p3 of the transient in turbine trip from highest level of power without reactor trip. In particular, a steady state with conditions very similar to the of the previous simulation made using the RELAP-MOD3 code has been obtained. In the transient, has been also satisfactory results, specifically the values of pressures, temperatures and mass flows, both in the secondary and primary circuit flow, are also very similar in both cases. In conclusion, have shown the ability to play the transition in study by the TRILLO plant using the code TRACE v5.0 p3 model, constituting a step in the process of verification of such a code. (Author)
Lin, Whei-Min; Hong, Chih-Ming [Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung 80424 (China)
2010-06-15
To achieve maximum power point tracking (MPPT) for wind power generation systems, the rotational speed of wind turbines should be adjusted in real time according to wind speed. In this paper, a Wilcoxon radial basis function network (WRBFN) with hill-climb searching (HCS) MPPT strategy is proposed for a permanent magnet synchronous generator (PMSG) with a variable-speed wind turbine. A high-performance online training WRBFN using a back-propagation learning algorithm with modified particle swarm optimization (MPSO) regulating controller is designed for a PMSG. The MPSO is adopted in this study to adapt to the learning rates in the back-propagation process of the WRBFN to improve the learning capability. The MPPT strategy locates the system operation points along the maximum power curves based on the dc-link voltage of the inverter, thus avoiding the generator speed detection. (author)
Maximum Output Power Control Using Short-Circuit Current and Open-Circuit Voltage of a Solar Panel
Kato, Takahiro; Miyake, Takuma; Tashima, Daisuke; Sakoda, Tatsuya; Otsubo, Masahisa; Hombu, Mitsuyuki
2012-10-01
A control method to optimize the output power of a solar cell is necessary because the output of a solar cell strongly depends on solar radiation. We here proposed two output power control methods using the short-circuit current and open-circuit voltage of a solar panel. One of them used a current ratio and a voltage ratio (αβ control), and the other used a current ratio and a short-circuit current-electric power characteristic coefficient (αγ control). The usefulness of the αβ and the αγ control methods was evaluated. The results showed that the output power controlled by our proposed methods was close to the maximum output power of a solar panel.
Maximum at ALS: A powerful tool to investigate open problems in micro and optoelectronics
Lorusso, G.F.; Solak, H.; Singh, S.; Cerrina, F. [Univ. of Wisconsin, Madison, WI (United States). Center of X-ray Lithography; Batson, P.J.; Underwood, J.H. [Lawrence Berkeley National Lab., CA (United States). Center of X-ray Optics
1998-12-31
The authors present recent results obtained by MAXIMUM at the Advanced Light Source (ALS), at the Lawrence Berkeley National Laboratory. MAXIMUM is a scanning photoemission microscope, based on a multilayer coated Schwarzschild objective. An electron energy analyzer collects the emitted photoelectrons to form an image as the sample itself is scanned. The microscope has been purposely designed to take advantage of the high brightness of the third generation synchrotron radiation sources, and its installation at ALS has been recently completed. The spatial resolution of 100 nm and the spectral resolution of 200 meV make the instrument an extremely interesting tool to investigate current problems in opto- and microelectronics. In order to illustrate the potential of MAXIMUM in these fields, the authors report new results obtained by studying the electromigration in Al-Cu lines and the Al segregation in AlGaN thin films.
Power-law distribution functions derived from maximum entropy and a symmetry relationship
Peterson, G J
2011-01-01
Power-law distributions are common, particularly in social physics. Here, we explore whether power-laws might arise as a consequence of a general variational principle for stochastic processes. We describe communities of 'social particles', where the cost of adding a particle to the community is shared equally between the particle joining the cluster and the particles that are already members of the cluster. Power-law probability distributions of community sizes arise as a natural consequence of the maximization of entropy, subject to this 'equal cost sharing' rule. We also explore a generalization in which there is unequal sharing of the costs of joining a community. Distributions change smoothly from exponential to power-law as a function of a sharing-inequality quantity. This work gives an interpretation of power-law distributions in terms of shared costs.
Pattern Recognition of High O3 Episodes in Forecasting Daily Maximum Ozone Levels
Jeong-Sook Heo
2004-01-01
Full Text Available In this study, a method was developed to diagnose ozone episodes exceeding environmental criteria (e.g., above 80 ppb on the basis of a multivariate statistical method and a fuzzy expert system. This method, being capable of characterizing the occurrence patterns of high-level ozone, was employed to forecast daily maximum ozone levels. The hourly data for both air pollutants and meteorological parameters, obtained both at the surface and at high elevation (500 hPa stations of Seoul City (1989-1996, were analyzed using this method. Through an application of the fuzzy expert system, the data sets were classified into 8 different types for common ozone episodes. In addition, the data sets were divided into patterns of 11 (Station A, 20 (Station B, 8 (Station C, and 10 (Station D for site-specific ozone episodes. The results of the analysis were successful in demonstrating that the method was sufficiently efficient to classify each class quantitatively with its own patterns of ozone pollution.
Ivashin V.A.
2013-12-01
Full Text Available Aims. The study presents the results of experimental research to verify the principle overlay for maximum permissible levels (MPL of multicolor laser radiation single exposure on eyes. This principle of the independence of the effects of radiation with each wavelength (the imposing principle, was founded and generalized to a wide range of exposure conditions. Experimental verification of this approach in relation to the impact of laser radiation on tissue fundus of an eye, as shows the analysis of the literature was not carried out. Material and methods. Was used in the experimental laser generating radiation with wavelengths: Л1 =0,532 microns, A2=0,556to 0,562 microns and A3=0,619to 0,621 urn. Experiments were carried out on eyes of rabbits with evenly pigmented eye bottom. Results. At comparison of results of processing of the experimental data with the calculated data it is shown that these levels are close by their parameters. Conclusions. For the first time in the Russian Federation had been performed experimental studies on the validity of multi-colored laser radiation on the organ of vision. In view of the objective coincidence of the experimental data with the calculated data, we can conclude that the mathematical formulas work.
Abdelhak Dida
2015-02-01
Full Text Available This paper proposes a novel variable speed control algorithm for a grid connected doubly-fed induction generator (DFIG system. The main objective is to track the maximum power curve characteristic by using an adaptive fuzzy logic controller, and to compare it with the conventional optimal torque control method for large inertia wind turbines. The role of the FLC is to adapt the transfer function of the harvested mechanical power controller according to the operating point in variable wind speed. The control system has two sub-systems for the rotor side and the grid side converters (RSC, GSC. Active and reactive power control of the back-to-back converters has been achieved indirectly by controlling q-axis and d-axis current components. The main function of the RSC controllers is to track the maximum power through controlling the electromagnetic torque of the wind turbine. The GSC controls the DC-link voltage, and guarantees unity power factor between the GSC and the grid. The proposed system is developed and tested in MATLAB/SimPowerSystem (SPS environment.
Zhaoyong Mao
2016-01-01
Full Text Available This paper addresses the power generation control system of a new drag-type Vertical Axis Turbine with several retractable blades. The returning blades can be entirely hidden in the drum, and negative torques can then be considerably reduced as the drum shields the blades. Thus, the power efficiency increases. Regarding the control, a Linear Quadratic Tracking (LQT optimal control algorithm for Maximum Power Point Tracking (MPPT is proposed to ensure that the wave energy conversion system can operate highly effectively under fluctuating conditions and that the tracking process accelerates over time. Two-dimensional Computational Fluid Dynamics (CFD simulations are performed to obtain the maximum power points of the turbine’s output. To plot the tip speed ratio curve, the least squares method is employed. The efficacy of the steady and dynamic performance of the control strategy was verified using Matlab/Simulink software. These validation results show that the proposed system can compensate for power fluctuations and is effective in terms of power regulation.
Izumida, Yuki; Okuda, Koji
2014-05-01
We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart.
Pilot power optimization for AF relaying using maximum likelihood channel estimation
Wang, Kezhi
2014-09-01
Bit error rates (BERs) for amplify-and-forward (AF) relaying systems with two different pilot-symbol-aided channel estimation methods, disintegrated channel estimation (DCE) and cascaded channel estimation (CCE), are derived in Rayleigh fading channels. Based on these BERs, the pilot powers at the source and at the relay are optimized when their total transmitting powers are fixed. Numerical results show that the optimized system has a better performance than other conventional nonoptimized allocation systems. They also show that the optimal pilot power in variable gain is nearly the same as that in fixed gain for similar system settings. andcopy; 2014 IEEE.
Tofael Ahmed
2014-06-01
Full Text Available In this paper, a single phase doubly grounded semi-Z-source inverter with maximum power point tracking (MPPT is proposed for photovoltaic (PV systems. This proposed system utilizes a single-ended primary inductor (SEPIC converter as DC-DC converter to implement the MPPT algorithm for tracking the maximum power from a PV array and a single phase semi-Z-source inverter for integrating the PV with AC power utilities. The MPPT controller utilizes a fast-converging algorithm to track the maximum power point (MPP and the semi-Z-source inverter utilizes a nonlinear SPWM to produce sinusoidal voltage at the output. The proposed system is able to track the MPP of PV arrays and produce an AC voltage at its output by utilizing only three switches. Experimental results show that the fast-converging MPPT algorithm has fast tracking response with appreciable MPP efficiency. In addition, the inverter shows the minimization of common mode leakage current with its ground sharing feature and reduction of the THD as well as DC current components at the output during DC-AC conversion.
Power Control for Maximum Throughput in Spectrum Underlay Cognitive Radio Networks
Tadrous, John; Nafie, Mohammed; El-Keyi, Amr
2010-01-01
We investigate power allocation for users in a spectrum underlay cognitive network. Our objective is to find a power control scheme that allocates transmit power for both primary and secondary users so that the overall network throughput is maximized while maintaining the quality of service (QoS) of the primary users greater than a certain minimum limit. Since an optimum solution to our problem is computationally intractable, as the optimization problem is non-convex, we propose an iterative algorithm based on sequential geometric programming, that is proved to converge to at least a local optimum solution. We use the proposed algorithm to show how a spectrum underlay network would achieve higher throughput with secondary users operation than with primary users operating alone. Also, we show via simulations that the loss in primary throughput due to the admission of the secondary users is accompanied by a reduction in the total primary transmit power.
Maximum efficiency of steady-state heat engines at arbitrary power.
Ryabov, Artem; Holubec, Viktor
2016-05-01
We discuss the efficiency of a heat engine operating in a nonequilibrium steady state maintained by two heat reservoirs. Within the general framework of linear irreversible thermodynamics we derive a universal upper bound on the efficiency of the engine operating at arbitrary fixed power. Furthermore, we show that a slight decrease of the power below its maximal value can lead to a significant gain in efficiency. The presented analysis yields the exact expression for this gain and the corresponding upper bound.
Carletta, Nicholas D.; Mullendore, Gretchen L.; Starzec, Mariusz; Xi, Baike; Feng, Zhe; Dong, Xiquan
2016-08-01
Convective mass transport is the transport of mass from near the surface up to the upper troposphere and lower stratosphere (UTLS) by a deep convective updraft. This transport can alter the chemical makeup and water vapor balance of the UTLS, which affects cloud formation and the radiative properties of the atmosphere. It is therefore important to understand the exact altitudes at which mass is detrained from convection. The purpose of this study was to improve upon previously published methodologies for estimating the level of maximum detrainment (LMD) within convection using data from a single ground-based radar. Four methods were used to identify the LMD and validated against dual-Doppler derived vertical mass divergence fields for six cases with a variety of storm types. The best method for locating the LMD was determined to be the method that used a reflectivity texture technique to determine convective cores and a multi-layer echo identification to determine anvil locations. Although an improvement over previously published methods, the new methodology still produced unreliable results in certain regimes. The methodology worked best when applied to mature updrafts, as the anvil needs time to grow to a detectable size. Thus, radar reflectivity is found to be valuable in estimating the LMD, but storm maturity must also be considered for best results.
Benefit-cost estimation for alternative drinking water maximum contaminant levels
Gurian, Patrick L.; Small, Mitchell J.; Lockwood, John R.; Schervish, Mark J.
2001-08-01
A simulation model for estimating compliance behavior and resulting costs at U.S. Community Water Suppliers is developed and applied to the evaluation of a more stringent maximum contaminant level (MCL) for arsenic. Probability distributions of source water arsenic concentrations are simulated using a statistical model conditioned on system location (state) and source water type (surface water or groundwater). This model is fit to two recent national surveys of source waters, then applied with the model explanatory variables for the population of U.S. Community Water Suppliers. Existing treatment types and arsenic removal efficiencies are also simulated. Utilities with finished water arsenic concentrations above the proposed MCL are assumed to select the least cost option compatible with their existing treatment from among 21 available compliance strategies and processes for meeting the standard. Estimated costs and arsenic exposure reductions at individual suppliers are aggregated to estimate the national compliance cost, arsenic exposure reduction, and resulting bladder cancer risk reduction. Uncertainties in the estimates are characterized based on uncertainties in the occurrence model parameters, existing treatment types, treatment removal efficiencies, costs, and the bladder cancer dose-response function for arsenic.
Ye, Zhuo-Lin; Li, Wei-Sheng; Lai, Yi-Ming; He, Ji-Zhou; Wang, Jian-Hui
2015-12-01
We propose a quantum-mechanical Brayton engine model that works between two superposed states, employing a single particle confined in an arbitrary power-law trap as the working substance. Applying the superposition principle, we obtain the explicit expressions of the power and efficiency, and find that the efficiency at maximum power is bounded from above by the function: η+ = θ/(θ + 1), with θ being a potential-dependent exponent. Supported by the National Natural Science Foundation of China under Grant Nos. 11505091, 11265010, and 11365015, and the Jiangxi Provincial Natural Science Foundation under Grant No. 20132BAB212009
Ramachandran, Hema; Pillai, K. P. P.; Bindu, G. R.
2016-08-01
A two-port network model for a wireless power transfer system taking into account the distributed capacitances using PP network topology with top coupling is developed in this work. The operating and maximum power transfer efficiencies are determined analytically in terms of S-parameters. The system performance predicted by the model is verified with an experiment consisting of a high power home light load of 230 V, 100 W and is tested for two forced resonant frequencies namely, 600 kHz and 1.2 MHz. The experimental results are in close agreement with the proposed model.
Janssen PJCM; Speijers GJA; CSR
1997-01-01
This report contains a basic step-to-step description of the procedure followed in the derivation of the human-toxicological Maximum Permissible Risk (MPR ; in Dutch: Maximum Toelaatbaar Risico, MTR) for soil contaminants. In recent years this method has been applied for a large number of compounds
Timing A Pulsed Thin Film Pyroelectric Generator For Maximum Power Denisty
Smith, A. N.; Hanrahan, B. M.; Neville, C. J.; Jankowski, N. R.
2016-11-01
Pyroelectric thermal-to-electric energy conversion is accomplished by a cyclic process of thermally-inducing polarization changes in the material under an applied electric field. The pyroelectric MEMS device investigated consisted of a thin film PZT capacitor with platinum bottom and iridium oxide top electrodes. Electric fields between 1-20 kV/cm with a 30% duty cycle and frequencies from 0.1 - 100 Hz were tested with a modulated continuous wave IR laser with a duty cycle of 20% creating temperature swings from 0.15 - 26 °C on the pyroelectric receiver. The net output power of the device was highly sensitive to the phase delay between the laser power and the applied electric field. A thermal model was developed to predict and explain the power loss associated with finite charge and discharge times. Excellent agreement was achieved between the theoretical model and the experiment results for the measured power density versus phase delay. Limitations on the charging and discharging rates result in reduced power and lower efficiency due to a reduced net work per cycle.
Ruikun Mai
2017-02-01
Full Text Available One of the most promising inductive power transfer applications is the wireless power supply for locomotives which may cancel the need for pantographs. In order to meet the dynamic and high power demands of wireless power supplies for locomotives, a relatively long transmitter track and multiple receivers are usually adopted. However, during the dynamic charging, the mutual inductances between the transmitter and receivers vary and the load of the locomotives also changes randomly, which dramatically affects the system efficiency. A maximum efficiency point tracking control scheme is proposed to improve the system efficiency against the variation of the load and the mutual inductances between the transmitter and receivers while considering the cross coupling between receivers. Firstly, a detailed theoretical analysis on dual receivers is carried out. Then a control scheme with three control loops is proposed to regulate the receiver currents to be the same, to regulate the output voltage and to search for the maximum efficiency point. Finally, a 2 kW prototype is established to validate the performance of the proposed method. The overall system efficiency (DC-DC efficiency reaches 90.6% at rated power and is improved by 5.8% with the proposed method under light load compared with the traditional constant output voltage control method.
Optimization of a Turboprop UAV for Maximum Loiter and Specific Power Using Genetic Algorithm
Dinc, Ali
2016-09-01
In this study, a genuine code was developed for optimization of selected parameters of a turboprop engine for an unmanned aerial vehicle (UAV) by employing elitist genetic algorithm. First, preliminary sizing of a UAV and its turboprop engine was done, by the code in a given mission profile. Secondly, single and multi-objective optimization were done for selected engine parameters to maximize loiter duration of UAV or specific power of engine or both. In single objective optimization, as first case, UAV loiter time was improved with an increase of 17.5% from baseline in given boundaries or constraints of compressor pressure ratio and burner exit temperature. In second case, specific power was enhanced by 12.3% from baseline. In multi-objective optimization case, where previous two objectives are considered together, loiter time and specific power were increased by 14.2% and 9.7% from baseline respectively, for the same constraints.
Test report on the Abacus 30 kW bimode{reg_sign} inverter and maximum power tracker (MPT)
Bonn, R.; Ginn, J.; Zirzow, J. [and others
1995-06-01
Sandia National Laboratories conducts the photovoltaic balance of systems (BOS) program, which is sponsored by the US Department of Energy`s Office of Energy Management. Under this program, SNL lets commercialization contracts and conducts a laboratory program designed to advance BOS technology, improve BOS component reliability, and reduce the BOS life-cycle-cost. This report details the testing of the first large US manufactured hybrid inverter and its associated maximum power tracker.
Hwu, K. I.; Tu, W. C.; Wang, C.R.
2013-01-01
A photovoltaic energy conversion system, constructed by high step-up converter with hybrid maximum power point tracking (HMPPT), is presented. A voltage converter with a high voltage conversion ratio is proposed, which is simple in circuit and easy in control. After this, such a converter operating with a suitable initial duty cycle of the pulsewidth-modulated (PWM) control signal, together with the proposed HMPPT algorithm combining the fractional open-circuit voltage method and the incremen...
Test report on the Abacus 30 kW bimode(reg sign) inverter and Maximum Power Tracker (MPT)
Bonn, Russell; Ginn, Jerry; Zirzow, Jeff; Sittler, Greg
1995-06-01
Sandia National Laboratories conducts the photovoltaic balance of systems (BOS) program, which is sponsored by the US Department of Energy's Office of Energy Management. Under this program, SNL lets commercialization contracts and conducts a laboratory program designed to advance BOS technology, improve BOS component reliability, and reduce the BOS life-cycle-cost. This report details the testing of the first large US manufactured hybrid inverter and its associated maximum power tracker.
Ahteshamul Haque
2016-01-01
The energy crisis concern leads to look for alternate source of energy. Solar energy is considered as most reliable among the all renewable energy sources. Solar PV (Photovoltaic) is used to convert solar energy into electric energy. The efficiency of solar PV is very low and its characteristic is nonlinear. To overcome these drawbacks a technique known as maximum power point tracking is used. This algorithm is implemented in the control circuit of DC – DC converter. The objective...
Ishida, Hiroshi; Hirose, Ryohei; Watanabe, Susumu
2012-10-01
The abdominal drawing-in maneuver (ADIM) is commonly used as a fundamental component of lumbar stabilization training programs. One potential limitation of lumbar stabilization programs is that it can be difficult and time consuming to train people to perform the ADIM. The transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles are the most powerful muscles involved in expiration. However, little is known about the differences in the recruitment of the abdominal muscles between the ADIM and breathe held at maximum expiratory level (maximum expiration). The thickness of the TrA and IO muscles was measured by ultrasound imaging, and the activity of the EO muscle was measured by electromyography (EMG) in 33 healthy male performing the ADIM and maximum expiration. Maximum expiration produced a significant increase in the thickness of the TrA and IO muscles compared to the ADIM (p muscle was significantly higher during maximum expiration than during the ADIM (p muscle was approximately 30% of the maximal voluntary contraction during maximum expiration. Thus, maximum expiration may be an effective method for training of co-activation of the lateral abdominal muscles.
Ru-Min Chao
2016-01-01
Full Text Available This paper identifies the partial shading problem of a PV module using the one-diode model and simulating the characteristics exhibiting multiple-peak power output condition that is similar to a PV array. A modified particle swarm optimization (PSO algorithm based on the suggested search-agent deployment, retracking condition, and multicore operation is proposed in order to continuously locate the global maximum power point for the PV system. Partial shading simulation results for up to 16 modules in series/parallel formats are presented. A distributed PV system consisting of up to 8 a-silicon thin film PV panels and also having a dedicated DC/DC buck converter on each of the modules is tested. The converter reaches its steady state voltage output in 10 ms. However for MPPT operation, voltage, and current measurement interval is set to 20 ms to avoid unnecessary noise from the entire electric circuit. Based on the simulation and experiment results, each core of the proposed PSO operation should control no more than 4 PV modules in order to have the maximum tracking accuracy and minimum overall tracking time. Tracking for the global maximum power point of a distributed PV system under various partial shading conditions can be done within 1.3 seconds.
Suliang Ma
2016-11-01
Full Text Available Photovoltaic (PV systems have non-linear characteristics that generate maximum power at one particular operating point. Environmental factors such as irradiance and temperature variations greatly affect the maximum power point (MPP. Diverse offline and online techniques have been introduced for tracking the MPP. Here, to track the MPP, an augmented-state feedback linearized (AFL non-linear controller combined with an artificial neural network (ANN is proposed. This approach linearizes the non-linear characteristics in PV systems and DC/DC converters, for tracking and optimizing the PV system operation. It also reduces the dependency of the designed controller on linearized models, to provide global stability. A complete model of the PV system is simulated. The existing maximum power-point tracking (MPPT and DC/DC boost-converter controller techniques are compared with the proposed ANN method. Two case studies, which simulate realistic circumstances, are presented to demonstrate the effectiveness and superiority of the proposed method. The AFL with ANN controller can provide good dynamic operation, faster convergence speed, and fewer operating-point oscillations around the MPP. It also tracks the global maxima under different conditions, especially irradiance-mutating situations, more effectively than the conventional methods. Detailed mathematical models and a control approach for a three-phase grid-connected intelligent hybrid system are proposed using MATLAB/Simulink.
Power System Structural Vulnerability Assessment based on an Improved Maximum Flow Approach
Fang, Jiakun; Su, Chi; Chen, Zhe
2017-01-01
to identify the critical lines in a system. The proposed method consists of two major steps. First, the power network is modeled as a graph with edges (transmission lines, transformers, etc.) and nodes (buses, substations, etc.). The critical scenarios are identified by using the principal component analysis...
Jui-Ho Chen
2014-03-01
Full Text Available This paper proposes a sliding mode extremum seeking control (SMESC of chaos embedded particle swarm optimization (CEPSO Algorithm, applied to the design of maximum power point tracking in wind power systems. Its features are that the control parameters in SMESC are optimized by CEPSO, making it unnecessary to change the output power of different wind turbines, the designed in-repetition rate is reduced, and the system control efficiency is increased. The wind power system control is designed by simulation, in comparison with the traditional wind power control method, and the simulated dynamic response obtained by the SMESC algorithm proposed in this paper is better than the traditional hill-climbing search (HCS and extremum seeking control (ESC algorithms in the transient or steady states, validating the advantages and practicability of the method proposed in this paper.
Aragon-Gonzalez, G; Leon-Galicia, A; Morales-Gomez, J R
2007-01-01
In this work we include, for the Carnot cycle, irreversibilities of linear finite rate of heat transferences between the heat engine and its reservoirs, heat leak between the reservoirs and internal dissipations of the working fluid. A first optimization of the power output, the efficiency and ecological function of an irreversible Carnot cycle, with respect to: internal temperature ratio, time ratio for the heat exchange and the allocation ratio of the heat exchangers; is performed. For the second and third optimizations, the optimum values for the time ratio and internal temperature ratio are substituted into the equation of power and, then, the optimizations with respect to the cost and effectiveness ratio of the heat exchangers are performed. Finally, a criterion of partial optimization for the class of irreversible Carnot engines is herein presented.
Design of a Maximum Power Point Tracker with Simulation, Analysis, and Comparison of Algorithms
2012-12-01
was discussed as well as designed around a single diode model. By modeling the solar array based on measured parameters, the output current and voltage ...Switched Capacitor Buck-Boost Converter for PV Application 11 2.7 A Novel MPPT Charge Regulator for a Photovoltaic Stand-alone Telecommu- nication...Simulink, which includes the solar array, buck converter, and resistive load. . . . . 16 Figure 3.2 The Current versus Voltage and Power versus Voltage
2012-12-01
portable devices where system size and efficiency are the primary design factors. Size and efficiency also govern the use of multiple MPPTs at the sub... mechanisms responsible for the energy losses in a switch-mode converter are the same. They include the components responsible for conduction, capacitor...designed to directly power a load as done in this test. The SPV-1020 may require an appropriate battery charger such as the STEVAL SEA05 battery
Electronic stopping power of hydrogen in KCl at the stopping maximum and at very low energies
Primetzhofer, D.; Markin, S. N.; Bauer, P.
2011-10-01
The electronic energy loss of hydrogen ions in KCl was investigated in a wide energy range. Thin films of KCl were evaporated on an Au/Si substrate. Rutherford Backscattering Spectrometry (RBS) was performed with protons and deuterons at energies from 30 to 400 keV/nucleon. At lower energies experiments were performed by Time-Of-Flight Low energy ion scattering (TOF-LEIS) again with proton and deuteron projectiles. Experimental results are compared to calculated/tabulated values for the electronic energy loss. Whereas at energies beyond the stopping maximum very good agreement is found, at lower ion energies discrepancies between experiment and calculations increase. At very low ion velocities the extrapolated stopping cross section ɛ predicts vanishing electronic energy loss at energies below 100 eV/nucleon.
北京电网风电发展与消纳能力%Development and Maximum Accommodating Capacity of Wind Power in Beijing Power Grid
余潇潇; 张璞; 刘兆燕; 左向红; 张凯; 田子婵
2015-01-01
结合北京地区风力资源分布情况及风力发电的并网现状，对北京地区风力发电的发展情况进行了预测。预测内容包括规划风力发电的输出特性，以及“十三五”期间北京地区风力发电的发展情况。提出了一种以电网的负荷特性、常规电源调峰能力、新能源处理特性及外受电力交换情况作为边界条件的风电消纳计算方法。运用该方法对北京电网“十二五”末及“十三五”末对风电的消纳能力进行了计算，并提出了促进北京电网风电发展的相关技术措施。%According to the distribution of wind energy resource and the present situation of wind power integration in Beijing, the forecast of wind power generation development in Beijing power grid was provided, which focused on the output characteristics of the planned wind power projects and the development of wind power generation in Beijing during the 13th national five￣year plan. A calculation method of the maximum proliferation ratio of wind power in Beijing power grid was proposed, whose boundary condition included the load characteristics of grid, the peak shift capability of local power generation plants, the new energy processing features and the power flow exchange limit with the outside grid. The method was used to calculate the maximum penetration ratio of wind power in Beijing power grid during the end of the 12th, 13th national five￣year plan. Finally, this paper suggested some related technical measures to promote the development of wind power in Beijing power grid.
Wei, J.; Lefeuvre, E.; Mathias, H.; Costa, F.
2016-12-01
The operation analysis of a new interface circuit for electrostatic vibration energy harvesting with adjustable bias voltage is carried out in this paper. Two configurations determined by the open or closed states of an electronic switch are examined. The increase of the voltage across a biasing capacitor, occurring when the switch is open, is proved theoretically and experimentally. With the decrease of this biasing voltage which occurs naturally when the switch is closed due to imperfections of the circuit, the bias voltage can be maintained close to a target value by appropriate ON and OFF control of the switch. As the energy converted by the variable capacitor on each cycle depends on the bias voltage, this energy can be therefore accurately controlled. This feature opens up promising perspectives for optimization the power harvested by electrostatic devices. Simulation results with and without electromechanical coupling effect are presented. In experimental tests, a simple switch control enabling to stabilize the bias voltage is described.
Shahrooz Hajighorbani
2016-01-01
Full Text Available This paper presents a hybrid maximum power point tracking (MPPT method to detect the global maximum power point (GMPP under partially shaded conditions (PSCs, which have more complex characteristics with multiple peak power points. The hybrid method can track the GMPP when a partial shadow occurs either before or after acquiring the MPP under uniform conditions. When PS occurs after obtaining the MPP during uniform conditions, the new operating point should be specified by the modified linear function, which reduces the searching zone of the GMPP and has a significant effect on reducing the reaching time of the GMPP. Simultaneously, the possible MPPs are scanned and stored when shifting the operating point to a new reference voltage. Finally, after determining the possible location of the GMPP, the GMPP is obtained using the modified P&O. Conversely, when PS occurs before obtaining the MPP, the referenced MPP should be specified. Thus, after recognizing the possible location of the GMPP, the modified P&O can be used to obtain the GMPP. The simulation and experimental implementations for the proposed algorithm are performed with different scenarios of shadowing under different irradiations, which clearly indicate that the proposed method is robust and has a fast tracking speed. Moreover, this work presents the load sizing method for PSCs to avoid controller failure when detecting the GMPP. Additionally, in this paper, the user-friendly method for programming the digital signal processing (DSP via Simulink/MATLAB is presented in detail.
Impact of CDMA wireless phone power output and puncture rate on hearing aid interference levels.
Fry, T L; Schlegel, R E; Grant, H
2000-01-01
Interference between digital wireless phones and hearing aids occurs when the radiofrequency bursts from the phone transmission are demodulated by the hearing aid amplifier. The amplified interference signal is heard as a "buzz" or "static" by the hearing aid wearer. Most research and standards development activity has focused on worst-case scenarios with the phone operating at its maximum power. Since this power level is often not typical in urban and suburban settings, it is of value to determine the impact of lower power levels on the overall level of audible interference. Using a frequency analyzer, and several hearings aids and code division multiple access (CDMA) phones, the audio frequency spectrum of interference was recorded for each phone-aid combination and for a range of power levels producing from no interference to maximum interference. As phone power is increased, the interference signal becomes distinguishable from the ambient noise level and a linear response region is observed in which a specified increase in power output results in a proportional increase in the overall input referenced interference level (OIRIL). As power is increased beyond the linear region, the hearing aid enters a saturation region where an additional power increase results in a reduction or no increase in the OIRIL. The numeric differences in interference documented in this study were used in conjunction with the results of a previous study by the authors to determine the impact of reduced power on speech intelligibility and annoyance. The amount of improvement for a given power reduction depends on the radiofrequency immunity of the hearing aid and is substantial for hearing aids with poor immunity. For high-immunity aids, the level of audible interference remains low even at high phone power levels.
Dual-Axis Solar Tracking System for Maximum Power Production in PV Systems
Muhd.Ikram Mohd. Rashid
2015-12-01
Full Text Available The power developed in a solar energy system depends fundamentally upon the amount of sunlight captured by the photovoltaic modules/arrays. This paper describes a simple electro-mechanical dual axis solar tracking system designed and developed in a study. The control of the two axes was achieved by the pulses generated from the data acquisition (DAQ card fed into four relays. This approach was so chosen to effectively avoid the error that usually arises in sensor-based methods. The programming of the mathematical models of the solar elevation and azimuth angles was done using Borland C++ Builder. The performance and accuracy of the developed system was evaluated with a PV panel at latitude 3.53o N and longitude 103.5o W in Malaysia. The results obtained reflect the effectiveness of the developed tracking system in terms of the energy yield when compared with that generated from a fixed panel. Overall, 20%, 23% and 21% additional energy were produced for the months of March, April and May respectively using the tracker developed in this study.
The History and Perspectives of Efficiency at Maximum Power of the Carnot Engine
Michel Feidt
2017-07-01
Full Text Available Finite Time Thermodynamics is generally associated with the Curzon–Ahlborn approach to the Carnot cycle. Recently, previous publications on the subject were discovered, which prove that the history of Finite Time Thermodynamics started more than sixty years before even the work of Chambadal and Novikov (1957. The paper proposes a careful examination of the similarities and differences between these pioneering works and the consequences they had on the works that followed. The modelling of the Carnot engine was carried out in three steps, namely (1 modelling with time durations of the isothermal processes, as done by Curzon and Ahlborn; (2 modelling at a steady-state operation regime for which the time does not appear explicitly; and (3 modelling of transient conditions which requires the time to appear explicitly. Whatever the method of modelling used, the subsequent optimization appears to be related to specific physical dimensions. The main goal of the methodology is to choose the objective function, which here is the power, and to define the associated constraints. We propose a specific approach, focusing on the main functions that respond to engineering requirements. The study of the Carnot engine illustrates the synthesis carried out and proves that the primary interest for an engineer is mainly connected to what we called Finite (physical Dimensions Optimal Thermodynamics, including time in the case of transient modelling.
Cisneros, Rafael; Gao, Rui; Ortega, Romeo; Husain, Iqbal
2016-10-01
The present paper proposes a maximum power extraction control for a wind system consisting of a turbine, a permanent magnet synchronous generator, a rectifier, a load and one constant voltage source, which is used to form the DC bus. We propose a linear PI controller, based on passivity, whose stability is guaranteed under practically reasonable assumptions. PI structures are widely accepted in practice as they are easier to tune and simpler than other existing model-based methods. Real switching based simulations have been performed to assess the performance of the proposed controller.
Djukanovic, M. (Inst. ' Nikola Tesla' , Belgrade (Yugoslavia)); Sobajic, D.J.; Yohhan Pao (Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Electrical Engineering and Applied Physics Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Computer Engineering and Science AI WARE inc., Cleveland, OH (United States))
1992-10-01
In heavily stressed power systems, post-fault transient voltage dips can lead to undesired tripping of industrial drives and large induction motors. The lowest transient voltage dips occur when fault clearing times are less than critical ones. In this paper, we propose a new iterative analytical methodology to obtain more accurate estimates of voltage dips at maximum angular swing in direct transient stability analysis. We also propose and demonstrate the possibility of storing the results of these computations in the associative memory (AM) system, which exhibits remarkable generalization capabilities. Feature-based models stored in the AM can be utilized for fast and accurate prediction of the location, duration and the amount of the worst voltage dips, thereby avoiding the need and cost for lengthy time-domain simulations. Numerical results obtained using the example of the New England power system are presented to illustrate our approach. (Author)
Her-Terng Yau
2013-01-01
Full Text Available An extremum seeking control (ESC scheme is proposed for maximum power point tracking (MPPT in photovoltaic power generation systems. The robustness of the proposed scheme toward irradiance changes is enhanced by implementing the ESC scheme using a sliding mode control (SMC law. In the proposed approach, the chattering phenomenon caused by high frequency switching is suppressed by means of a sliding layer concept. Moreover, in implementing the proposed controller, the optimal value of the gain constant is determined using a particle swarm optimization (PSO algorithm. The experimental and simulation results show that the proposed PSO-based sliding mode ESC (SMESC control scheme yields a better transient response, steady-state stability, and robustness than traditional MPPT schemes based on gradient detection methods.
Chen, Xi Lin; De Santis, Valerio; Umenei, Aghuinyue Esai
2014-07-07
In this study, the maximum received power obtainable through wireless power transfer (WPT) by a small receiver (Rx) coil from a relatively large transmitter (Tx) coil is numerically estimated in the frequency range from 100 kHz to 10 MHz based on human body exposure limits. Analytical calculations were first conducted to determine the worst-case coupling between a homogeneous cylindrical phantom with a radius of 0.65 m and a Tx coil positioned 0.1 m away with the radius ranging from 0.25 to 2.5 m. Subsequently, three high-resolution anatomical models were employed to compute the peak induced field intensities with respect to various Tx coil locations and dimensions. Based on the computational results, scaling factors which correlate the cylindrical phantom and anatomical model results were derived. Next, the optimal operating frequency, at which the highest transmitter source power can be utilized without exceeding the exposure limits, is found to be around 2 MHz. Finally, a formulation is proposed to estimate the maximum obtainable power of WPT in a typical room scenario while adhering to the human body exposure compliance mandates.
Missing Data Imputation versus Full Information Maximum Likelihood with Second-Level Dependencies
Larsen, Ross
2011-01-01
Missing data in the presence of upper level dependencies in multilevel models have never been thoroughly examined. Whereas first-level subjects are independent over time, the second-level subjects might exhibit nonzero covariances over time. This study compares 2 missing data techniques in the presence of a second-level dependency: multiple…
Power Analysis in Two-Level Unbalanced Designs
Konstantopoulos, Spyros
2010-01-01
Previous work on statistical power has discussed mainly single-level designs or 2-level balanced designs with random effects. Although balanced experiments are common, in practice balance cannot always be achieved. Work on class size is one example of unbalanced designs. This study provides methods for power analysis in 2-level unbalanced designs…
The Maximum Power of the Wind Power System Based on Extreme Value Method%基于极值法的风电系统最大功率
陆玲黎; 吴雷
2011-01-01
针对风力发电系统的最大功率问题,提出以极值法为依据捕获最大功率的方法.分析了风力机的工作原理及功率特性,讨论了影响功率的主要因素.通过对极值搜索法的基本理论及特点的解析,结合其工作原理,得出功率曲线是占空比的凹函数,因此极值搜索法通过控制占空比来提高风能的捕获效率,并通过改进提高了抗干扰能力和稳定性.实验结果证明了该方法的可行性.%In order to overcome the trouble brought by wind power generation system for maximum power,this paper puts forward a method based on extreme value method to capture the maximum power.The working principle of wind turbine and power characteristics are analyzed,the main factors affecting the power is discussed.Through the analysis of extremum search method on the basic theory and characteristics which combined with its working principle, come to a decision that power curve is concave function of duty cycle.Therefore,extreme value search method can control the duty cycle to improve the efficiency of wind capture, and improve anti-interference ability and stability .Through experiments, the final experimental curves obtained prove the feasibility of the method.
Shareef, Hussain; Mutlag, Ammar Hussein; Mohamed, Azah
2017-01-01
Many maximum power point tracking (MPPT) algorithms have been developed in recent years to maximize the produced PV energy. These algorithms are not sufficiently robust because of fast-changing environmental conditions, efficiency, accuracy at steady-state value, and dynamics of the tracking algorithm. Thus, this paper proposes a new random forest (RF) model to improve MPPT performance. The RF model has the ability to capture the nonlinear association of patterns between predictors, such as irradiance and temperature, to determine accurate maximum power point. A RF-based tracker is designed for 25 SolarTIFSTF-120P6 PV modules, with the capacity of 3 kW peak using two high-speed sensors. For this purpose, a complete PV system is modeled using 300,000 data samples and simulated using the MATLAB/SIMULINK package. The proposed RF-based MPPT is then tested under actual environmental conditions for 24 days to validate the accuracy and dynamic response. The response of the RF-based MPPT model is also compared with that of the artificial neural network and adaptive neurofuzzy inference system algorithms for further validation. The results show that the proposed MPPT technique gives significant improvement compared with that of other techniques. In addition, the RF model passes the Bland-Altman test, with more than 95 percent acceptability.
Zagrouba, M.; Sellami, A.; Bouaicha, M. [Laboratoire de Photovoltaique, des Semi-conducteurs et des Nanostructures, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, Tunis, B.P. 95, 2050 Hammam-Lif (Tunisia); Ksouri, M. [Unite de Recherche RME-Groupe AIA, Institut National des Sciences Appliquees et de Technologie (Tunisia)
2010-05-15
In this paper, we propose to perform a numerical technique based on genetic algorithms (GAs) to identify the electrical parameters (I{sub s}, I{sub ph}, R{sub s}, R{sub sh}, and n) of photovoltaic (PV) solar cells and modules. These parameters were used to determine the corresponding maximum power point (MPP) from the illuminated current-voltage (I-V) characteristic. The one diode type approach is used to model the AM1.5 I-V characteristic of the solar cell. To extract electrical parameters, the approach is formulated as a non convex optimization problem. The GAs approach was used as a numerical technique in order to overcome problems involved in the local minima in the case of non convex optimization criteria. Compared to other methods, we find that the GAs is a very efficient technique to estimate the electrical parameters of PV solar cells and modules. Indeed, the race of the algorithm stopped after five generations in the case of PV solar cells and seven generations in the case of PV modules. The identified parameters are then used to extract the maximum power working points for both cell and module. (author)
Power estimation on functional level for programmable processors
M. Schneider
2004-01-01
Full Text Available In diesem Beitrag werden verschiedene Ansätze zur Verlustleistungsschätzung von programmierbaren Prozessoren vorgestellt und bezüglich ihrer Übertragbarkeit auf moderne Prozessor-Architekturen wie beispielsweise Very Long Instruction Word (VLIW-Architekturen bewertet. Besonderes Augenmerk liegt hierbei auf dem Konzept der sogenannten Functional-Level Power Analysis (FLPA. Dieser Ansatz basiert auf der Einteilung der Prozessor-Architektur in funktionale Blöcke wie beispielsweise Processing-Unit, Clock-Netzwerk, interner Speicher und andere. Die Verlustleistungsaufnahme dieser Bl¨ocke wird parameterabhängig durch arithmetische Modellfunktionen beschrieben. Durch automatisierte Analyse von Assemblercodes des zu schätzenden Systems mittels eines Parsers können die Eingangsparameter wie beispielsweise der erzielte Parallelitätsgrad oder die Art des Speicherzugriffs gewonnen werden. Dieser Ansatz wird am Beispiel zweier moderner digitaler Signalprozessoren durch eine Vielzahl von Basis-Algorithmen der digitalen Signalverarbeitung evaluiert. Die ermittelten Schätzwerte für die einzelnen Algorithmen werden dabei mit physikalisch gemessenen Werten verglichen. Es ergibt sich ein sehr kleiner maximaler Schätzfehler von 3%. In this contribution different approaches for power estimation for programmable processors are presented and evaluated concerning their capability to be applied to modern digital signal processor architectures like e.g. Very Long InstructionWord (VLIW -architectures. Special emphasis will be laid on the concept of so-called Functional-Level Power Analysis (FLPA. This approach is based on the separation of the processor architecture into functional blocks like e.g. processing unit, clock network, internal memory and others. The power consumption of these blocks is described by parameter dependent arithmetic model functions. By application of a parser based automized analysis of assembler codes of the systems to be estimated
Reactive Power Impact on Lifetime Prediction of Two-level Wind Power Converter
Zhou, Dao; Blaabjerg, Frede; Lau, M.
2013-01-01
The influence of reactive power injection on the dominating two-level wind power converter is investigated and compared in terms of power loss and thermal behavior. Then the lifetime of both the partial-scale and full-scale power converter is estimated based on the widely used Coffin-Manson model...
blood glucose level in Bufo gutturalis (power)
Department of Human Physiology and Physiological Chemistry, ... the influence of dehydration on the blood glucose level of anurans. .... J. Cell. Compo Physiol. 44: 233 - 246. VAWDA, A. 1978. The loss of sodium across the skin of the.
Reactive Power Impact on Lifetime Prediction of Two-level Wind Power Converter
Zhou, Dao; Blaabjerg, Frede; Lau, M.;
2013-01-01
The influence of reactive power injection on the dominating two-level wind power converter is investigated and compared in terms of power loss and thermal behavior. Then the lifetime of both the partial-scale and full-scale power converter is estimated based on the widely used Coffin-Manson model....... It is concluded that the injection of the reactive power could have serious impact on the power loss and thermal profile, especially at lower wind speed. Furthermore, the introduction of the reactive power could also shorten the lifetime of the wind power converter significantly....
Design of Three-Phase Three-Level CIC T-Source Inverter with Maximum Boost Control
Shults, Tatiana; Husev, Oleksandr; Roncero-Clemente, Carlos
2015-01-01
This paper presents guidelines for component design of the three-level three-phase T-source inverter with continuous input current under maximum boost control proposed recently. Steady state analysis under low-frequency current and voltage ripples in the dc side was made. Component sizes for both...
Michelle Lim Sern Mi
2013-01-01
Full Text Available This research work presents a novel architecture of an Ultra-Low-Power (ULP based Hybrid Energy Harvester (HEH consisting of multiple input sources such as kinetic, thermal and solar energy, harvested from passive human power. Having multiple ambient sources mitigates limitations caused by single sources especially for bodily-worn applications; however, this results in impedance mismatch among the different integrated sources. To overcome this limitation, the proposed ULP-HEH will use one power management unit with Maximum Power Point Tracking (MPPT algorithm and impedance matching considerations to efficiently manage and combine power harvested from all three sources to achieve ULP consumptions. Among other crucial sub-modules of the ULP-HEH are its Asynchronous Finite State Machine (AFSM cum resource sharing arbiter to prioritize and share energy sources for overall power reduction, an efficient rectification scheme for the piezoelectric input, an adaptive feedback for ULP conditioning, Zero-Current Switching (ZCS for semi-lossless switching, a self-start circuit for low ambient startup, a Boost converter, a Buck regulator, a fuzzy-based micro-battery charger and a de-multiplexer to switch between harvesting or charging capabilities. All of which are implemented for maximum output extraction and minimal losses. This ULP-HEH will be developed in PSPICE software, Verilog coding under Mentor Graphics environment and later to be verified using Field Programmable Gate Array (FPGA board before the final layout implementation in CMOS 0.13-Âµm process technology. This battery-less ULP-HEH is expected to deliver 3.0-5.0V of regulated voltage output from low ambient sources of 35 mV at startup. An efficiency of 90% with an output power of 650 Âµm is expected when all sources are summed. Also, this ULP-HEH is aimed at reducing power consumption to at least twice (<70 ÂµW of conventional approaches. The proposed ULP-HEH can be used for ULP bodily
The Power of Cross-Level Partnerships.
Youngerman, Stephanie
1998-01-01
Much credit for the tangible feeling of caring at an Idaho elementary school is due to partnerships that faculty, families, and students have forged across grade levels. These cross-grade buddy systems have put the brakes on bullies, fostered student friendships, and resolved personality conflicts among staff members. (MLH)
Analysis of superconducting microstrip resonator at various microwave power levels
Srivastava, G.P.; Jacob, M.V.; Jayakumar, M.; Bhatnagar, P.K. [Department of Electronic Science, University of Delhi, South Campus, Benito Juarez Road, New Delhi 110021 (India); Kataria, N.D. [National Physical Laboratory, K. S. Krishnan Road, New Delhi 110 012 (India)
1997-05-01
The real and imaginary parts of the surface impedance of YBCO superconductors have been studied at different microwave power levels. Using the relations for the critical current density and the grain boundary resistance, a relation for calculating the power dependence of the surface resistance has been obtained. Also, a relation to find the resonant frequency of a superconducting microstrip resonator at various input power levels has been derived. Measurements have been carried out on various microstrip resonators to study the variation of surface resistance and resonant frequency at different rf power levels. The experimental results are in good agreement with theoretical results. {copyright} {ital 1997 American Institute of Physics.}
Challenges with Tertiary-Level Mechatronic Fluid Power
Dransfield, Peter; Conrad, Finn
1996-01-01
As authors we take the view that mechatronics, as it relates to fluid power, has three levels which we designate as primary, secondary and tertiary. A brief review of the current status of fluid power, hydraulic and pneumatic, and of electronic control of it is presented and discussed. The focus...... is then on tertiary-level mechatronic fluid power and the challenges to it being applied successfully....
Extreme value analysis of annual maximum water levels in the Pearl River Delta, China
Qiang ZHANG; Chong-Yu XU; Yongqin David CHEN; Chun-ling LIU
2009-01-01
We analyzed the statistical properties of water level extremes in the Pearl River Delta using five probability distribution functions. Estimation of para-meters was performed using the L-moment technique.Goodness-of-fit was done based on Kolmogorov-Smirnov's statistic D (K-S D). The research results indicate that Wakeby distribution is the best statistical model for description of statistical behaviors of water level extremes in the study region. Statistical analysis indicates that water levels corresponding to different return periods and associated variability tend to be larger in the landward side of the Pearl River Delta and vice versa. A ridge characterized by higher water level can be identified expanding along the West River and the Modaomen channel, showing the impacts of the hydrologic process of the West River basin. Trough and higher grades of water level changes can be detected in the region drained by Xi'nanyong channel, Dongping channel, and mainstream of Pearl River. The Pearl River Delta region is character-ized by low-lying topography and a highly-advanced socio-economy, and is heavily populated, being prone to flood hazards and flood inundation due to rising sea level and typhoons. Therefore, sound and effective counter-measures should be made for human mitigation to natural hazards such as floods and typhoons.
Locational Marginal Pricing in the Campus Power System at the Power Distribution Level
Hao, Jun; Gu, Yi; Zhang, Yingchen; Zhang, Jun Jason; Gao, David Wenzhong
2016-11-14
In the development of smart grid at distribution level, the realization of real-time nodal pricing is one of the key challenges. The research work in this paper implements and studies the methodology of locational marginal pricing at distribution level based on a real-world distribution power system. The pricing mechanism utilizes optimal power flow to calculate the corresponding distributional nodal prices. Both Direct Current Optimal Power Flow and Alternate Current Optimal Power Flow are utilized to calculate and analyze the nodal prices. The University of Denver campus power grid is used as the power distribution system test bed to demonstrate the pricing methodology.
Al-Amoudi, A.; Zhang, L. [University of Leeds (United Kingdom). School of Electronic and Electrical Engineering
2000-09-01
A neural-network-based approach for solar array modelling is presented. The logic hidden unit of the proposed network consists of a set of nonlinear radial basis functions (RBFs) which are connected directly to the input vector. The links between hidden and output units are linear. The model can be trained using a random set of data collected from a real photovoltaic (PV) plant. The training procedures are fast and the accuracy of the trained models is comparable with that of the conventional model. The principle and training procedures of the RBF-network modelling when applied to emulate the I/V characteristics of PV arrays are discussed. Simulation results of the trained RBF networks for modelling a PV array and predicting the maximum power points of a real PV panel are presented. (author)
WANG Yang; TU Zhan-Chun
2013-01-01
The Carnot-like heat engines are classified into three types (normal-,sub-and,super-dissipative) according to relations between the minimum irreversible entropy production in the "isothermal" processes and the time for completing those processes.The efficiencies at maximum power of normal-,sub-and super-dissipative Carnot-like heat engines are proved to be bounded between ηc/2 and ηc/ (2-ηc),ηc/2 and ηc,0 and ηc/ (2-ηc),respectively.These bounds are also shared by linear,sub-and super-linear irreversible Carnot-like engines [Tu and Wang,Europhys.Lett.98 (2012) 40001] although the dissipative engines and the irreversible ones are inequivalent to each other.
Wilson, Robert M.
1990-01-01
The level of skill in predicting the size of the sunspot cycle is investigated for the two types of precursor techniques, single variate and bivariate fits, both applied to cycle 22. The present level of growth in solar activity is compared to the mean level of growth (cycles 10-21) and to the predictions based on the precursor techniques. It is shown that, for cycle 22, both single variate methods (based on geomagnetic data) and bivariate methods suggest a maximum amplitude smaller than that observed for cycle 19, and possibly for cycle 21. Compared to the mean cycle, cycle 22 is presently behaving as if it were a +2.6 sigma cycle (maximum amplitude of about 225), which means that either it will be the first cycle not to be reliably predicted by the combined precursor techniques or its deviation relative to the mean cycle will substantially decrease over the next 18 months.
Ahmadian, Radin
2010-09-01
This study investigated the relationship of anthocyanin concentration from different organic fruit species and output voltage and current in a TiO2 dye-sensitized solar cell (DSSC) and hypothesized that fruits with greater anthocyanin concentration produce higher maximum power point (MPP) which would lead to higher current and voltage. Anthocyanin dye solution was made with crushing of a group of fresh fruits with different anthocyanin content in 2 mL of de-ionized water and filtration. Using these test fruit dyes, multiple DSSCs were assembled such that light enters through the TiO2 side of the cell. The full current-voltage (I-V) co-variations were measured using a 500 Ω potentiometer as a variable load. Point-by point current and voltage data pairs were measured at various incremental resistance values. The maximum power point (MPP) generated by the solar cell was defined as a dependent variable and the anthocyanin concentration in the fruit used in the DSSC as the independent variable. A regression model was used to investigate the linear relationship between study variables. Regression analysis showed a significant linear relationship between MPP and anthocyanin concentration with a p-value of 0.007. Fruits like blueberry and black raspberry with the highest anthocyanin content generated higher MPP. In a DSSC, a linear model may predict MPP based on the anthocyanin concentration. This model is the first step to find organic anthocyanin sources in the nature with the highest dye concentration to generate energy.
Raynald Labrecque
2009-11-01
Full Text Available It is known that mechanical work, and in turn electricity, can be produced from a difference in the chemical potential that may result from a salinity gradient. Such a gradient may be found, for instance, in an estuary where a stream of soft water is flooding into a sink of salty water which we may find in an ocean, gulf or salt lake. Various technological approaches are proposed for the production of energy from a salinity gradient between a stream of soft water and a source of salty water. Before considering the implementation of a typical technology, it is of utmost importance to be able to compare various technological approaches, on the same basis, using the appropriate variables and mathematical formulations. In this context, exergy balance can become a very useful tool for an easy and quick evaluation of the maximum thermodynamic work that can be produced from energy systems. In this short paper, we briefly introduce the use of exergy for enabling us to easily and quickly assess the theoretical maximum power or ideal reversible work we may expect from typical salinity gradient energy systems.
Experimental Study of a Multi Level Overtopping Wave Power Device
Kofoed, Jens Peter; Hald, Tue; Frigaard, Peter Bak
2002-01-01
Results of experimental investigations of a floating wave energy device called Power Pyramid is presented. The Power Pyramid utilizes reservoirs in multiple levels when capturing wave overtopping and converting it into electrical energy. The effect of capturing the overtopping in multiple levels......, compared to only one level, has been evaluated experimentally. From the experimental results, and the performed optimizations based on these, it has been found that the efficiency of a wave power device of the overtopping type can be increased by as much as 76 % by using 5 levels instead of 1. However...
张红光; 宋吉江; 翟义成; 陈洁; 刘圆圆
2012-01-01
基于光伏电池的工程模型,利用MATLAB中的simulink模块,建立光伏电池的近似模型,并仿真出不同温度下的光伏电池输出特性.仿真结果表明,该模型能够快速响应光照强度变化.当光照强度突变时,能够快速实现最大功率跟踪.%Based on simulation mode1 of photovoltaic cell,the output characteristic of photovaltaic cell was simulated at different temperatures with simulink blocks of MATLAB.A pratical model for photovoltaic block was developed.Simulations results show that the PV model can respond to the changes of insolation level quickly.When insolation level changes,it can quickly achieve maximum power point tracking and achieve good results.
A. Sluijs
2011-01-01
Full Text Available A brief (~150 kyr period of widespread global average surface warming marks the transition between the Paleocene and Eocene epochs, ~56 million years ago. This so-called "Paleocene-Eocene thermal maximum" (PETM is associated with the massive injection of ^{13}C-depleted carbon, reflected in a negative carbon isotope excursion (CIE. Biotic responses include a global abundance peak (acme of the subtropical dinoflagellate Apectodinium. Here we identify the PETM in a marine sedimentary sequence deposited on the East Tasman Plateau at Ocean Drilling Program (ODP Site 1172 and show, based on the organic paleothermometer TEX_{86}, that southwest Pacific sea surface temperatures increased from ~26 °C to ~33°C during the PETM. Such temperatures before, during and after the PETM are >10 °C warmer than predicted by paleoclimate model simulations for this latitude. In part, this discrepancy may be explained by potential seasonal biases in the TEX_{86} proxy in polar oceans. Additionally, the data suggest that not only Arctic, but also Antarctic temperatures may be underestimated in simulations of ancient greenhouse climates by current generation fully coupled climate models. An early influx of abundant Apectodinium confirms that environmental change preceded the CIE on a global scale. Organic dinoflagellate cyst assemblages suggest a local decrease in the amount of river run off reaching the core site during the PETM, possibly in concert with eustatic rise. Moreover, the assemblages suggest changes in seasonality of the regional hydrological system and storm activity. Finally, significant variation in dinoflagellate cyst assemblages during the PETM indicates that southwest Pacific climates varied significantly over time scales of 10^{3} – 10^{4} years during this event, a finding comparable to similar studies of PETM successions from the New Jersey Shelf.
Algorithmic analysis of the maximum level length in general-block two-dimensional Markov processes
2006-01-01
Full Text Available Two-dimensional continuous-time Markov chains (CTMCs are useful tools for studying stochastic models such as queueing, inventory, and production systems. Of particular interest in this paper is the distribution of the maximal level visited in a busy period because this descriptor provides an excellent measure of the system congestion. We present an algorithmic analysis for the computation of its distribution which is valid for Markov chains with general-block structure. For a multiserver batch arrival queue with retrials and negative arrivals, we exploit the underlying internal block structure and present numerical examples that reveal some interesting facts of the system.
Favarel, C.; Champier, D.; Bédécarrats, J. P.; Kousksou, T.; Strub, F.
2012-06-01
According to the International Energy Agency, 1.4 billion people are without electricity in the poorest countries and 2.5 billion people rely on biomass to meet their energy needs for cooking in developing countries. The use of cooking stoves equipped with small thermoelectric generator to provide electricity for basic needs (LED, cell phone and radio charging device) is probably a solution for houses far from the power grid. The cost of connecting every house with a landline is a lot higher than dropping thermoelectric generator in each house. Thermoelectric generators have very low efficiency but for isolated houses, they might become really competitive. Our laboratory works in collaboration with plane`te-bois (a non governmental organization) which has developed energy-efficient multifunction (cooking and hot water) stoves based on traditional stoves designs. A prototype of a thermoelectric generator (Bismuth Telluride) has been designed to convert a small part of the energy heating the sanitary water into electricity. This generator can produce up to 10 watts on an adapted load. Storing this energy in a battery is necessary as the cooking stove only works a few hours each day. As the working point of the stove varies a lot during the use it is also necessary to regulate the electrical power. An electric DC DC converter has been developed with a maximum power point tracker (MPPT) in order to have a good efficiency of the electronic part of the thermoelectric generator. The theoretical efficiency of the MMPT converter is discussed. First results obtained with a hot gas generator simulating the exhaust of the combustion chamber of a cooking stove are presented in the paper.
Castrillon, Julio
2015-11-10
We develop a multi-level restricted Gaussian maximum likelihood method for estimating the covariance function parameters and computing the best unbiased predictor. Our approach produces a new set of multi-level contrasts where the deterministic parameters of the model are filtered out thus enabling the estimation of the covariance parameters to be decoupled from the deterministic component. Moreover, the multi-level covariance matrix of the contrasts exhibit fast decay that is dependent on the smoothness of the covariance function. Due to the fast decay of the multi-level covariance matrix coefficients only a small set is computed with a level dependent criterion. We demonstrate our approach on problems of up to 512,000 observations with a Matérn covariance function and highly irregular placements of the observations. In addition, these problems are numerically unstable and hard to solve with traditional methods.
Use of existing standards to measure sound power levels of powered hand tools-necessary revisions
Hayden, Charles S.; Zechmann, Edward
2005-09-01
At recent NOISE-CON and Acoustical Society of America meetings, noise rating labeling was discussed as a way of manufacturers providing full disclosure information for their noise emitting products. The first step is to gather sound power level data from these products. Sound power level data should be gathered in accordance with existing ANSI and/or ISO standards. Some standards, such as ANSI 12.15, may not define true operational noise emissions[r1] and thus may provide inaccurate information when that information is used to choose a hearing protection device or used to make a purchasing decision. A number of standards were systematically combined by NIOSH researchers to provide the most accurate information on sound power levels of powered hand tools used in the construction industry. This presentation will detail some of the challenges of existing ANSI 12.15 (and draft ANSI 12.41) to measure sound power levels of electric (and pneumatic) powered hand tools.
Calebe A. Matias
2017-07-01
Full Text Available The purpose of the present study is to simulate and analyze an isolated full-bridge DC/DC boost converter, for photovoltaic panels, running a modified perturb and observe maximum power point tracking method. The zero voltage switching technique was used in order to minimize the losses of the converter for a wide range of solar operation. The efficiency of the power transfer is higher than 90% for large solar operating points. The panel enhancement due to the maximum power point tracking algorithm is 5.06%.
Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.
2017-06-01
This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconom ic impacts. The full report is contained in 27 volumes.
Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.
2017-06-01
This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.
Huang, Yu
Solar energy becomes one of the major alternative renewable energy options for its huge abundance and accessibility. Due to the intermittent nature, the high demand of Maximum Power Point Tracking (MPPT) techniques exists when a Photovoltaic (PV) system is used to extract energy from the sunlight. This thesis proposed an advanced Perturbation and Observation (P&O) algorithm aiming for relatively practical circumstances. Firstly, a practical PV system model is studied with determining the series and shunt resistances which are neglected in some research. Moreover, in this proposed algorithm, the duty ratio of a boost DC-DC converter is the object of the perturbation deploying input impedance conversion to achieve working voltage adjustment. Based on the control strategy, the adaptive duty ratio step size P&O algorithm is proposed with major modifications made for sharp insolation change as well as low insolation scenarios. Matlab/Simulink simulation for PV model, boost converter control strategy and various MPPT process is conducted step by step. The proposed adaptive P&O algorithm is validated by the simulation results and detail analysis of sharp insolation changes, low insolation condition and continuous insolation variation.
Ying-Yi Hong
2016-01-01
Full Text Available This work proposes an enhanced particle swarm optimization scheme that improves upon the performance of the standard particle swarm optimization algorithm. The proposed algorithm is based on chaos search to solve the problems of stagnation, which is the problem of being trapped in a local optimum and with the risk of premature convergence. Type 1′′ constriction is incorporated to help strengthen the stability and quality of convergence, and adaptive learning coefficients are utilized to intensify the exploitation and exploration search characteristics of the algorithm. Several well known benchmark functions are operated to verify the effectiveness of the proposed method. The test performance of the proposed method is compared with those of other popular population-based algorithms in the literature. Simulation results clearly demonstrate that the proposed method exhibits faster convergence, escapes local minima, and avoids premature convergence and stagnation in a high-dimensional problem space. The validity of the proposed PSO algorithm is demonstrated using a fuzzy logic-based maximum power point tracking control model for a standalone solar photovoltaic system.
Power Consideration for Three-Level Growth Models
Li, Wei; Konstantopoulos, Spyros
2016-01-01
The purpose of this study is extend previous methods by Raudenbush and Liu (2001) and Spybrook et al. (2011), and provide methods for power analysis of tests of treatment effects in studies of polynomial change with two levels of nesting (e.g., students and schools) where the treatment is either at the third level (e.g., school intervention) or at…
Schmid, Gernot; Kuster, Niels
2015-02-01
The objective of this paper is to compare realistic maximum electromagnetic exposure of human tissues generated by mobile phones with electromagnetic exposures applied during in vitro experiments to assess potentially adverse effects of electromagnetic exposure in the radiofrequency range. We reviewed 80 in vitro studies published between 2002 and present that concern possible adverse effects of exposure to mobile phones operating in the 900 and 1800 MHz bands. We found that the highest exposure level averaged over the cell medium that includes evaluated cells (monolayer or suspension) used in 51 of the 80 studies corresponds to 2 W/kg or less, a level below the limit defined for the general public. That does not take into account any exposure non-uniformity. For comparison, we estimated, by numerical means using dipoles and a commercial mobile phone model, the maximum conservative exposure of superficial tissues from sources operated in the 900 and 1800 MHz bands. The analysis demonstrated that exposure of skin, blood, and muscle tissues may well exceed 40 W/kg at the cell level. Consequently, in vitro studies reporting minimal or no effects in response to maximum exposure of 2 W/kg or less averaged over the cell media, which includes the cells, may be of only limited value for analyzing risk from realistic mobile phone exposure. We, therefore, recommend future in vitro experiments use specific absorption rate levels that reflect maximum exposures and that additional temperature control groups be included to account for sample heating.
El-Zoghby, Helmy M.; Bendary, Ahmed F.
2016-10-01
Maximum Power Point Tracking (MPPT) is now widely used method in increasing the photovoltaic (PV) efficiency. The conventional MPPT methods have many problems concerning the accuracy, flexibility and efficiency. The MPP depends on the PV temperature and solar irradiation that randomly varied. In this paper an artificial intelligence based controller is presented through implementing of an Adaptive Neuro-Fuzzy Inference System (ANFIS) to obtain maximum power from PV. The ANFIS inputs are the temperature and cell current, and the output is optimal voltage at maximum power. During operation the trained ANFIS senses the PV current using suitable sensor and also senses the temperature to determine the optimal operating voltage that corresponds to the current at MPP. This voltage is used to control the boost converter duty cycle. The MATLAB simulation results shows the effectiveness of the ANFIS with sensing the PV current in obtaining the MPPT from the PV.
Yang, Yongheng; Koutroulis, Eftichios; Sangwongwanich, Ariya
2015-01-01
Several countries with considerable PhotoVoltaic (PV) installations are facing a challenge of overloading the power infrastructure during peak-power production hours. Regulations have been imposed on the PV systems, where more active power control should be flexibly performed. As an advanced...... control strategy, the Absolute Active Power Control (AAPC) can effectively solve the overloading issues by limiting the maximum possible PV power to a certain level (i.e., the power limitation), and also benefit the inverter reliability. However, its feasibility is challenged by the energy loss....... An increase of the inverter lifetime and a reduction of the energy yield can alter the cost of energy, demanding an optimization of the power limitation. Therefore, aiming at minimizing the Levelized Cost of Energy (LCOE), the power limit is optimized for the AAPC strategy in this paper. The optimization...
Groszko, Marian
2003-01-01
Electric and magnetic fields of 50 Hz from electric power devices affect not only workers, but also the general population, as these devices are also located in populated areas, hence the duality of regulations on maximum admissible intensities. This paper presents these regulations and discusses in detail the changes of 2001. Based on the Polish regulations, hygienic evaluation of electric power devices has been attempted. The Polish regulations on the 50 Hz electromagnetic fields were compared with relevant international regulations of CENELEC and the European Union recommendations. Our maximum admissible intensities have been found to conform with the international standards.
Aasvang, Gunn Marit; Moum, Torbjorn; Engdahl, Bo
2008-07-01
The objective of the present survey was to study self-reported sleep disturbances due to railway noise with respect to nighttime equivalent noise level (L(p,A,eq,night)) and maximum noise level (L(p,A,max)). A sample of 1349 people in and around Oslo in Norway exposed to railway noise was studied in a cross-sectional survey to obtain data on sleep disturbances, sleep problems due to noise, and personal characteristics including noise sensitivity. Individual noise exposure levels were determined outside of the bedroom facade, the most-exposed facade, and inside the respondents' bedrooms. The exposure-response relationships were analyzed by using logistic regression models, controlling for possible modifying factors including the number of noise events (train pass-by frequency). L(p,A,eq,night) and L(p,A,max) were significantly correlated, and the proportion of reported noise-induced sleep problems increased as both L(p,A,eq,night) and L(p,A,max) increased. Noise sensitivity, type of bedroom window, and pass-by frequency were significant factors affecting noise-induced sleep disturbances, in addition to the noise exposure level. Because about half of the study population did not use a bedroom at the most-exposed side of the house, the exposure-response curve obtained by using noise levels for the most-exposed facade underestimated noise-induced sleep disturbance for those who actually have their bedroom at the most-exposed facade.
A fast method of maximum power point tracking for PV%一种快速的光伏最大功率点跟踪方法
高志强; 王建赜; 纪延超; 谭光慧; 张举良
2012-01-01
太阳能电池的输出功率受外界温度、光照强度和负载影响具有特殊的非线性.为了使输出功率始终工作在最大点处从而提高系统的整体效率,最大功率点跟踪在光伏系统中有很重要的意义,通过理论仿真分析,在温度不变的情况下,太阳能电池的输出电压变化不大,随着光照强度的变化最大功率点近似在一条直线上,和输出电流成线性关系.所采用新颖最大功率点跟踪方法是根据估算的最大功率点和输出电流成线性关系把P-I输出曲线划分成两个独立区域,在区域Ⅰ和区域Ⅱ分别采用变步长的观测比较法和变斜率的观测比较法快速调节输出电流使其接近或者等于最大功率点电流,达到快速跟踪最大功率点的目的.通过Matlab/Simulink软件仿真结果表明此种方法与扰动观测控制相比较,不仅能保证快速的跟踪光伏模块最大输出功率点,而且不会引起在最大功率点附近频繁波动,最后通过实验加以验证.%In order to ensure that the PV module always works at the maximum point of power to increase the system's overall efficiency, maximum power point tracking is crucial, since the output power of solar panels is influenced by special nonlinear conditions, such as outside temperature, light intensity and impact of load. This paper presents a novel photovoltaic maximum power point tracking method. The theoretical simulation shows that while the temperature is constant, the output voltage changes little, and with the change of the light intensity, the maximum power point approximates into a straight line, namely the maximum power point and the corresponding output current have a linear relationship. The proposed maximum power point tracking method is based on the maximum power point estimated and the corresponding linear output current curve, dividing the P-I output curve into two regions, and adjusting the output current through different control criteria
无
2009-01-01
Maximum power output of a class of irreversible non-regeneration heat engines with non-uniform working fluid,in which heat transfers between the working fluid and the heat reservoirs obey the linear phenomenological heat transfer law [q ∝Δ(T-1)],are studied in this paper. Optimal control theory is used to determine the upper bounds of power of the heat engine for the lumped-parameter model and the distributed-parameter model,respectively. The results show that the maximum power output of the heat engine in the distributed-parameter model is less than or equal to that in the lumped-parameter model,which could provide more realistic guidelines for real heat engines. Analytical solutions of the maximum power output are obtained for the irreversible heat engines working between constant temperature reservoirs. For the irreversible heat engine operating between variable temperature reservoirs,a numerical example for the lumped-parameter model is provided by numerical calculation. The effects of changes of reservoir’s temperature on the maximum power of the heat engine are analyzed. The obtained results are,in addition,compared with those obtained with Newtonian heat transfer law [q ∝Δ(T)].
Thawing of foods in a microwave oven: I. Effect of power levels and power cycling.
Chamchong, M; Datta, A K
1999-01-01
Microwave thawing is faster than other methods, but it can produce significant non-uniformity of heating. The objective of this study was to perform comprehensive experimentation and heat transfer modeling to relate the time to thaw and the non-uniformity of thawing to power cycling, power level and the surface heat transfer coefficient. The governing energy equation was formulated with an exponential decay of the microwave flux from the surface. Surface microwave flux was obtained from the measured temperature rise using inverse heat transfer analysis. Gradual phase change was formulated as an apparent specific heat, and was obtained for the experimental material tylose from differential scanning calorimetry (DSC) measurements. The temperatures were measured immediately following heating with a fast response thermocouple. Dielectric properties were measured above freezing. Results show that the microwave flux at the surface and its decay are affected by the changes in the power level. Power cycling has an almost identical effect as continuous power at the reduced level of the average cycled power. As power level increases, the surface flux increases by the same fraction. At higher power levels, however, the outside thaws relatively faster. A "shield" develops due to a much reduced microwave penetration depth at the surface. This thawing time at higher power levels is reduced considerably. Temperature increases initially are non-uniform since the surface is heated at a faster rate than the interior. In keeping with the assumption that once the temperature reaches 100 degrees C, all energy absorbed goes into evaporation, and subsequent temperature is maintained at 100 degrees C. Thus, eventually, non-uniformity starts to decrease.
2012-07-06
... census data, an estimated 1.3 million people live within a 50-mi (80.5-km) radius of St. Lucie within... projects. The nearest city limits from the plant site on the Atlantic coast are Port St. Lucie... Atlantic Ocean. Approximately 800 people are currently employed at St. Lucie on a full-time basis. For the...
Kupczewska-Dobecka, Małgorzata; Soćko, Renata; Czerczak, Sławomir
2006-01-01
The aim of this work is to analyse Maximum Admissible Concentration (MAC) values proposed for irritants by the Group of Experts for Chemical Agents in Poland, based on the RD50 value. In 1994-2004, MAC values for irritants based on the RD50 value were set for 17 chemicals. For the purpose of the analysis, 1/10 RD50, 1/100 RD50 and the MAC/RD50 ratio were calculated. The determined MAC values are within the 0.01-0.09 RD50 range. The RD50 value is a good rough criterion to set MAC values for irritants and it makes it possible to estimate quickly admissible exposure levels. It has become clear that, in some cases, simple setting the MAC value for an irritant at the level of 0.03 RD50 may be insufficient to determine precisely the possible hazard to workers' health. Other available toxicological data, such as NOAEL (No-Observed-Adverse-Effect Level) and LOAEL (Lowest-Observed-Adverse-Effect Level), should always be considered as well.
Battery Energy Storage System for PV Output Power Leveling
Rajkiran Singh
2014-01-01
Full Text Available Fluctuating photovoltaic (PV output power reduces the reliability in power system when there is a massive penetration of PV generators. Energy storage systems that are connected to the PV generators using bidirectional isolated dc-dc converter can be utilized for compensating the fluctuating PV power. This paper presents a grid connected energy storage system based on a 2 kW full-bridge bidirectional isolated dc-dc converter and a PWM converter for PV output power leveling. This paper proposes two controllers: a current controller using the d-q synchronous reference and a phase-shift controller. The main function of the current controller is to regulate the voltage at the high-side dc, so that the voltage ratio of the high-voltage side (HVS with low-voltage side (LVS is equal to the transformer turns ratio. The phase-shift controller is employed to manage the charging and discharging modes of the battery based on PV output power and battery voltage. With the proposed system, unity power factor and efficient active power injection are achieved. The feasibility of the proposed control system is investigated using PSCAD simulation.
Mroczka, Janusz; Ostrowski, Mariusz
2015-06-01
Disadvantages of photovoltaic panels are their low efficiency and non-linear current-voltage characteristic. Therefore it is necessary to apply the maximum power tracking systems which are dependent on the sun exposure and temperature. Trackers, that are used in photovoltaic systems, differ from each other in the speed and accuracy of tracking. Typically, in order to determine the maximum power point, trackers use measure of current and voltage. The perturb and observe algorithm or the incremental conductance method are frequent in the literature. The drawback of these solutions is the need to search the entire current-voltage curve, resulting in a significant loss of power in the fast-changing lighting conditions. Modern solutions use an additional measurement of temperature, short-circuit current or open circuit voltage in order to determine the starting point of one of the above methods, what decreases the tracking time. For this paper, a sequence of simulations and tests in real shading and temperature conditions for the investigated method, which uses additional light sensor to increase the speed of the perturb and observe algorithm in fast-changing illumination conditions was performed. Due to the non-linearity of the light sensor and the photovoltaic panel and the influence of temperature on the used sensor and panel characteristics, we cannot directly determine the relationship between them. For this reason, the tested method is divided into two steps. In the first step algorithm uses the correlation curve of the light sensor and current at the maximum power point and determines the current starting point with respect of which the perturb and observe algorithm is run. When the maximum power point is reached, in a second step, the difference between the starting point and the actual maximum power point is calculated and on this basis the coefficients of correlation curve are modified.
Aerobic Capacity and Anaerobic Power Levels of the University Students
Taskin, Cengiz
2016-01-01
The aim of study was to analyze aerobic capacity and anaerobic power levels of the university students. Total forty university students who is department physical education and department business (age means; 21.15±1.46 years for male and age means; 20.55±1.79 years for female in department physical education), volunteered to participate in this…
Protoflight photovoltaic power module system-level tests in the space power facility
Rivera, Juan C.; Kirch, Luke A.
1989-01-01
Work Package Four, which includes the NASA-Lewis and Rocketdyne, has selected an approach for the Space Station Freedom Photovoltaic (PV) Power Module flight certification that combines system level qualification and acceptance testing in the thermal vacuum environment: The protoflight vehicle approach. This approach maximizes ground test verification to assure system level performance and to minimize risk of on-orbit failures. The preliminary plans for system level thermal vacuum environmental testing of the protoflight PV Power Module in the NASA-Lewis Space Power Facility (SPF), are addressed. Details of the facility modifications to refurbish SPF, after 13 years of downtime, are briefly discussed. The results of an evaluation of the effectiveness of system level environmental testing in screening out incipient part and workmanship defects and unique failure modes are discussed. Preliminary test objectives, test hardware configurations, test support equipment, and operations are presented.
Design of megawatt power level heat pipe reactors
Mcclure, Patrick Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Poston, David Irvin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dasari, Venkateswara Rao [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reid, Robert Stowers [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-11-12
An important niche for nuclear energy is the need for power at remote locations removed from a reliable electrical grid. Nuclear energy has potential applications at strategic defense locations, theaters of battle, remote communities, and emergency locations. With proper safeguards, a 1 to 10-MWe (megawatt electric) mobile reactor system could provide robust, self-contained, and long-term power in any environment. Heat pipe-cooled fast-spectrum nuclear reactors have been identified as a candidate for these applications. Heat pipe reactors, using alkali metal heat pipes, are perfectly suited for mobile applications because their nature is inherently simpler, smaller, and more reliable than “traditional” reactors. The goal of this project was to develop a scalable conceptual design for a compact reactor and to identify scaling issues for compact heat pipe cooled reactors in general. Toward this goal two detailed concepts were developed, the first concept with more conventional materials and a power of about 2 MWe and a the second concept with less conventional materials and a power level of about 5 MWe. A series of more qualitative advanced designs were developed (with less detail) that show power levels can be pushed to approximately 30 MWe.
Setyawan, Daddy; Rohman, Budi
2014-09-01
Verification of Maximum Radial Power Peaking Factor due to insertion of FPM-LEU target in the core of RSG-GAS Reactor. Radial Power Peaking Factor in RSG-GAS Reactor is a very important parameter for the safety of RSG-GAS reactor during operation. Data of radial power peaking factor due to the insertion of Fission Product Molybdenum with Low Enriched Uranium (FPM-LEU) was reported by PRSG to BAPETEN through the Safety Analysis Report RSG-GAS for FPM-LEU target irradiation. In order to support the evaluation of the Safety Analysis Report incorporated in the submission, the assessment unit of BAPETEN is carrying out independent assessment in order to verify safety related parameters in the SAR including neutronic aspect. The work includes verification to the maximum radial power peaking factor change due to the insertion of FPM-LEU target in RSG-GAS Reactor by computational method using MCNP5and ORIGEN2. From the results of calculations, the new maximum value of the radial power peaking factor due to the insertion of FPM-LEU target is 1.27. The results of calculations in this study showed a smaller value than 1.4 the limit allowed in the SAR.
Setyawan, Daddy, E-mail: d.setyawan@bapeten.go.id [Center for Assessment of Regulatory System and Technology for Nuclear Installations and Materials, Indonesian Nuclear Energy Regulatory Agency (BAPETEN), Jl. Gajah Mada No. 8 Jakarta 10120 (Indonesia); Rohman, Budi [Licensing Directorate for Nuclear Installations and Materials, Indonesian Nuclear Energy Regulatory Agency (BAPETEN), Jl. Gajah Mada No. 8 Jakarta 10120 (Indonesia)
2014-09-30
Verification of Maximum Radial Power Peaking Factor due to insertion of FPM-LEU target in the core of RSG-GAS Reactor. Radial Power Peaking Factor in RSG-GAS Reactor is a very important parameter for the safety of RSG-GAS reactor during operation. Data of radial power peaking factor due to the insertion of Fission Product Molybdenum with Low Enriched Uranium (FPM-LEU) was reported by PRSG to BAPETEN through the Safety Analysis Report RSG-GAS for FPM-LEU target irradiation. In order to support the evaluation of the Safety Analysis Report incorporated in the submission, the assessment unit of BAPETEN is carrying out independent assessment in order to verify safety related parameters in the SAR including neutronic aspect. The work includes verification to the maximum radial power peaking factor change due to the insertion of FPM-LEU target in RSG-GAS Reactor by computational method using MCNP5and ORIGEN2. From the results of calculations, the new maximum value of the radial power peaking factor due to the insertion of FPM-LEU target is 1.27. The results of calculations in this study showed a smaller value than 1.4 the limit allowed in the SAR.
On-chip power-combining techniques for watt-level linear power amplifiers in 0.18 μm CMOS
Zhixiong, Ren; Kefeng, Zhang; Lanqi, Liu; Cong, Li; Xiaofei, Chen; Dongsheng, Liu; Zhenglin, Liu; Xuecheng, Zou
2015-09-01
Three linear CMOS power amplifiers (PAs) with high output power (more than watt-level output power) for high data-rate mobile applications are introduced. To realize watt-level output power, there are two 2.4 GHz PAs using an on-chip parallel combining transformer (PCT) and one 1.95 GHz PA using an on-chip series combining transformer (SCT) to combine output signals of multiple power stages. Furthermore, some linearization techniques including adaptive bias, diode linearizer, multi-gated transistors (MGTR) and the second harmonic control are applied in these PAs. Using the proposed power combiner, these three PAs are designed and fabricated in TSMC 0.18 μm RFCMOS process. According to the measurement results, the proposed two linear 2.4 GHz PAs achieve a gain of 33.2 dB and 34.3 dB, a maximum output power of 30.7 dBm and 29.4 dBm, with 29% and 31.3% of peak PAE, respectively. According to the simulation results, the presented linear 1.95 GHz PA achieves a gain of 37.5 dB, a maximum output power of 34.3 dBm with 36.3% of peak PAE. Project supported by the National Natural Science Foundation of China (No. 61076030).
Fractional-power-law level statistics due to dynamical tunneling.
Bäcker, Arnd; Ketzmerick, Roland; Löck, Steffen; Mertig, Normann
2011-01-14
For systems with a mixed phase space we demonstrate that dynamical tunneling universally leads to a fractional power law of the level-spacing distribution P(s) over a wide range of small spacings s. Going beyond Berry-Robnik statistics, we take into account that dynamical tunneling rates between the regular and the chaotic region vary over many orders of magnitude. This results in a prediction of P(s) which excellently describes the spectral data of the standard map. Moreover, we show that the power-law exponent is proportional to the effective Planck constant h(eff).
A. M. Yusop
2017-02-01
Full Text Available This study presents the development of a novel maximum-power point-tracking (MPPT method based on an input shaping scheme controller. The proposed method that changes the initial input response into a shapeable MPPT algorithm is designed based on an exponential input function. This type of input function is selected because of its capability to stabilize the system at the end of the simulation time and remain at the same condition at the final response time. A comparison of the system with the proposed method and the system with traditional perturb and observe (PnO method is also provided. Results show that the system with the proposed method produces higher output power than the system with PnO method; the difference is approximately 15.45%. Results reveal that the exponential function input shaper allows the overall output system to exhibit satisfactory behavior and can efficiently track the maximum output power.
2004-01-01
A high-level consumption estimation methodology and its associated tool, SoftExplorer, are presented. The estimation methodology uses a functional modeling of the processor combined with a parametric model to allow the designer to estimate the power consumption when the embedded software is executed on the target. SoftExplorer uses as input the assembly code generated by the compiler; its efficiency is compared to SimplePower's approach. Results for different processors (TI C62, C67, C55 and ...
Chatterjee, Nilanjan; Chen, Yi-Hau; Maas, Paige; Carroll, Raymond J
2016-03-01
Information from various public and private data sources of extremely large sample sizes are now increasingly available for research purposes. Statistical methods are needed for utilizing information from such big data sources while analyzing data from individual studies that may collect more detailed information required for addressing specific hypotheses of interest. In this article, we consider the problem of building regression models based on individual-level data from an "internal" study while utilizing summary-level information, such as information on parameters for reduced models, from an "external" big data source. We identify a set of very general constraints that link internal and external models. These constraints are used to develop a framework for semiparametric maximum likelihood inference that allows the distribution of covariates to be estimated using either the internal sample or an external reference sample. We develop extensions for handling complex stratified sampling designs, such as case-control sampling, for the internal study. Asymptotic theory and variance estimators are developed for each case. We use simulation studies and a real data application to assess the performance of the proposed methods in contrast to the generalized regression (GR) calibration methodology that is popular in the sample survey literature.
Ronquillo, Cecinio C; Zaugg, Brian; Stagg, Brian; Kirk, Kevin R; Gupta, Isha; Barlow, William R; Pettey, Jeff H; Olson, Randall J
2014-12-01
To determine the optimal longitudinal power settings for Infiniti OZil Intelligent Phaco (IP) at varying torsional amplitude settings; and to test the hypothesis that increasing longitudinal power is more important at lower torsional amplitudes to achieve efficient phacoemulsification. Laboratory investigation. setting: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. procedure: Individual porcine nuclei were fixed in formalin, then cut into 2.0 mm cubes. Lens cube phacoemulsification was done using OZil IP at 60%, 80%, and 100% torsional amplitude with 0%, 10%, 20%, 30%, 50%, 75%, or 100% longitudinal power. All experiments were done using a 20 gauge 0.9 mm bent reverse bevel phaco tip at constant vacuum (550 mm Hg), aspiration rate (40 mL/min), and bottle height (50 cm). main outcome measure: Complete lens particle phacoemulsification (efficiency). Linear regression analysis showed a significant increase in efficiency with increasing longitudinal power at 60% torsional amplitude (R(2) = 0.7269, P = .01) and 80% torsional amplitude (R(2) = 0.6995, P = .02) but not at 100% amplitude (R(2) = 0.3053, P = .2). Baseline comparison of 60% or 80% vs 100% torsional amplitude without longitudinal power showed increased efficiency at 100% (P = .0004). Increasing longitudinal power to 20% abolished the efficiency difference between 80% vs 100% amplitudes. In contrast, 75% longitudinal power abolished the efficiency difference between 60% vs 100% torsional amplitudes. Results suggest that longitudinal power becomes more critical at increasing phacoemulsification efficiencies at torsional amplitudes less than 100%. Increasing longitudinal power does not further increase efficiency at maximal torsional amplitudes. Copyright © 2014 Elsevier Inc. All rights reserved.
LIN; Kuang-Jang; LIN; Chii-Ruey
2010-01-01
The Photovoltaic Array has a best optimal operating point where the array operating can obtain the maximum power.However, the optimal operating point can be compromised by the strength of solar radiation,angle,and by the change of environment and load.Due to the constant changes in these conditions,it has become very difficult to locate the optimal operating point by following a mathematical model.Therefore,this study will focus mostly on the application of Fuzzy Logic Control theory and Three-point Weight Comparison Method in effort to locate the optimal operating point of solar panel and achieve maximum efficiency in power generation. The Three-point Weight Comparison Method is the comparison between the characteristic curves of the voltage of photovoltaic array and output power;it is a rather simple way to track the maximum power.The Fuzzy Logic Control,on the other hand,can be used to solve problems that cannot be effectively dealt with by calculation rules,such as concepts,contemplation, deductive reasoning,and identification.Therefore,this paper uses these two kinds of methods to make simulation successively. The simulation results show that,the Three-point Comparison Method is more effective under the environment with more frequent change of solar radiation;however,the Fuzzy Logic Control has better tacking efficiency under the environment with violent change of solar radiation.
Jian Zhao
2017-01-01
Full Text Available Partial shading (PS is an unavoidable condition which significantly reduces the efficiency and stability of a photovoltaic (PV system. With PS, the system usually exhibits multiple-peak output power characteristics, but single-peak is also possible under special PS conditions. In fact it is shown that the partial shading condition (PSC is the necessary but not sufficient condition for multiple-peak. Based on circuit analysis, this paper shows that the number of peak points can be determined by short-circuit currents and maximum-power point currents of all the arrays in series. Then the principle is established based on which the number of the peak points is to be determined. Furthermore, based on the dynamic characteristic of solar array, this paper establishes the rule for determination of the relative position of the global maximum power point (GMPP. In order to track the GMPP within an appropriate period, a reliable technique and the corresponding computer algorithm are developed for GMPP tracking (GMPPT control. It exploits a definable nonlinear relation has been found between variable environmental parameters and the output current of solar arrays at every maximum power point, obtained based on the dynamic performance corresponding to PSC. Finally, the proposed method is validated with MATLAB®/Simulink® simulations and actual experiments. It is shown that the GMPPT of a PV generation system is indeed realized efficiently in a realistic environment with partial shading conditions.
SEVEN LEVEL CONTROL OF SHUNT ACTIVE POWER FILTER FOR POWER QUALITY ENHANCEMENT
G. JAYAKRISHNA
2011-09-01
Full Text Available Shunt Active Power Filter (SAPF is one of the controllers to enhance power quality (PQ. This paper presents Hybrid Cascaded Seven-Level Inverter (HCSLI used in SAPF to compensate reactive power, improve the power factor and to suppress the total harmonic distortion (THD in supply current due to linear load and Non- Linear Diode Rectifier Loads (NLDRLs.In this paper d-q reference frame theory for reference current computation, Constant Switching Frequency Multicarrier Sub-Harmonic Pulse Width Modulation (CSFMSHPWM technique for controlling the switches of HCSLI, Fuzzy logic controller (FLC for regulating dc side capacitor voltage are proposed. The results are validated through simulation using Mat Lab/simulink with and without SAPF for linear and nonlinear loads.
Device for timing and power level setting for microwave applications
Ursu, M.-P.; Buidoş, T.
2016-08-01
Nowadays, the microwaves are widely used for various technological processes. The microwaves are emitted by magnetrons, which have strict requirements concerning power supplies for anode and filament cathodes, intensity of magnetic field, cooling and electromagnetic shielding. The magnetrons do not tolerate any alteration of their required voltages, currents and magnetic fields, which means that their output microwave power is fixed, so the only way to alter the power level is to use time-division, by turning the magnetron on and off by repetitive time patterns. In order to attain accurate and reproducible results, as well as correct and safe operation of the microwave device, all these requirements must be fulfilled. Safe, correct and reproducible operation of the microwave appliance can be achieved by means of a specially built electronic device, which ensures accurate and reproducible exposure times, interlocking of the commands and automatic switch off when abnormal operating conditions occur. This driving device, designed and realized during the completion of Mr.Ursu's doctoral thesis, consists of a quartz time-base, several programmable frequency and duration dividers, LED displays, sensors and interlocking gates. The active and passive electronic components are placed on custom-made PCB's, designed and made by means of computer-aided applications and machines. The driving commands of the electronic device are delivered to the magnetron power supplies by means of optic zero-passing relays. The inputs of the electronic driving device can sense the status of the microwave appliance. The user is able to enter the total exposure time, the division factor that sets the output power level and, as a novelty, the clock frequency of the time divider.
风电场最大注入容量的研究%RESEARCH ON CAPACITY OF WIND FARM MAXIMUM POWER INTEGRATION
王湘明; 高杨; 刘丽钧
2012-01-01
In recent years, with the increasing development and application of wind power technology, the proportion of the wind power in power system has grown up, consequently the connecting wind power had impacted much on power system. In this paper, it studies of variable speed constant frequency doubly fed wind turbine, separately join 3-kind-turbine wind farms to IEEE-14. A method combined of steady and transient state has been used to analyse the maximum capacity of power systems, and ensure the wind farm capacity maintained the system stability. Simulation results show that the number of the turbines connecting to the system will be proportional to the its power, thus determine the maximum capacity of the wind farm. The method is used to determine the largest wind farm connecting to power system capacity, thus can guarantee its own wind farm and the system stability.%以变速恒频双馈风电机组为研究对象,对IEEE-14系统分别加入3种不同功率的风力发电机组成的风电场,采用稳态和暂态相结合的方法对最大装机容量进行分析,确定能使系统保持稳定的风电场容量.仿真计算结果表明,不同功率的风机并入系统中的台数与其功率有一定的比例关系,从而确定了风电场的最大容量.利用该方法确定的风电场接入电力系统最大容量,可保证风电场自身及系统运行的稳定性.
Kouchaki, Alireza; Iman-Eini, H.; Asaei, B.
2012-01-01
This paper presents a new algorithm based on characteristic equation of solar cells to determine the Maximum Power Point (MPP) of PV modules under partially shaded conditions (PSC). To achieve this goal, an analytic condition is introduced to determine uniform or non-uniform atmospheric condition...... to verify the accuracy and validity of the proposed method, different simulations are carried out in MATLAB-Simulink environment for various atmospheric conditions. © 2012 IEEE....
Moreira, Andre Pimentel; Ramalho, Geraldo Luis Bezerra; Dias, Samuel Vieira [Centro Federal de Educacao Tecnologica do Ceara (CEFETCE), Fortaleza, CE (Brazil)], emails: apmoreira@cefetce.br, gramalho@cefetce.br, samueldias@cefetce.br; Carvalho, Paulo Cesar Marques de [Universidade Federal do Ceara (PPGEE/UFC), Fortaleza, CE (Brazil). Programa de Pos Graduacao em Engenharia Eletrica], e-mail: carvalho@dee.ufc.br; Borges Neto, Manuel Rangel [Centro Federal de Educacao Tecnologica de Petrolina (CEFETPet), Petrolina, PE (Brazil)], email: rangel@cefetpet.br
2008-07-01
This article is presented the study and compared the behaviour of real and simulated a photovoltaic system, through the design and simulation software, Electronic Workbench (MultiSIM 9), AIM-Spice and identifying the point of maximum power (MPP), with the help of modeling software from Matlab. The results of the simulated model were very close to data collected from a real.photovoltaic system. (author)
Sound power and vibration levels for two different piano soundboards
Squicciarini, Giacomo; Valiente, Pablo Miranda; Thompson, David J.
2016-09-01
This paper compares the sound power and vibration levels for two different soundboards for upright pianos. One of them is made of laminated spruce and the other of solid spruce (tone-wood). These differ also in the number of ribs and manufacturing procedure. The methodology used is defined in two major steps: (i) acoustic power due to a unit force is obtained reciprocally by measuring the acceleration response of the piano soundboards when excited by acoustic waves in reverberant field; (ii) impact tests are adopted to measure driving point and spatially-averaged mean-square transfer mobility. The results show that, in the midhigh frequency range, the soundboard made of solid spruce has a greater vibrational and acoustic response than the laminated soundboard. The effect of string tension is also addressed, showing that is only relevant at low frequencies.
Smit, Jeroen; Berghammer, Lars O.; Navalkar, Sachin;
2014-01-01
In this paper an extension of the spectrum of applicability of rotors with active aerody-namic devices is presented. Besides the classical purpose of load alleviation, a secondary objective is established: power capture optimization. As a _rst step, wind speed regions that contribute little...
Smit, Jeroen; Bernhammer, Lars O.; Navalkar, Sachin T.;
2016-01-01
An extension of the spectrum of applicability of rotors with active aerodynamic devices is presented in this paper. Besides the classical purpose of load alleviation, a secondary objective is established: optimization of power capture. As a first step, wind speed regions that contribute little...
Senju, T.; Uezato, K. [University of the Ryukyus, Okinawa (Japan); Tokumura, M. [Okinawa Electric Power Co. Inc., Okinawa (Japan)
1996-11-20
In recent years, exploitation of natural energy by saving fossil energy is being reconsidered. One of the expected sources of natural energy for the future is wind energy, which has been actively studied as a substitute source of energy for the world. However, the wind energy is influenced by geographic and weather conditions. So that the generating power varies with time. Therefore, in order to make the windmill generator system to extract available maximum power from wind energy. This paper proposes a tracking control method of maximum power operating point using the recursively least square method with forgetting factor. The proposed method is simple since it identifies the system parameters and controls the actual rotor speed by means of a PI controller. The system parameters are identified by using the information for generating power and windmill speed. We verify the effectiveness of the proposed control method with numerical simulations and experimental. 11 refs., 12 figs., 3 tabs.
刘圣波; 刘贺; 赵燕东
2013-01-01
为了提高光伏太阳能转换率，拓展传统纹波控制技术的应用，该文提出了离散时间纹波控制算法，通过对纹波控制技术的离散化处理，将最大功率点跟踪控制问题转换为离散采样-控制问题。以太阳能板输出电压为状态量，在其处于极大值和极小值时对系统进行采样；随后采取离散时间纹波控制算法使系统快速追踪到系统的最大功率点。该文在Simulink系统中对离散时间纹波控制算法进行了仿真。仿真结果表明，在1000和200 W/cm2，25℃的条件下，算法均可以快速准确地追踪到太阳能系统的最大功率点，追踪精度高达96%；在外部环境由1000变为200 W/cm2时，系统能够在0.1 s内准确地追踪到新的最大功率点。%Solar photovoltaic technology has been widely used in modern agriculture. Due to the volatility of solar power, it is hard to maximize the use of solar energy. In order to seek a way to improve the conversion rate of photovoltaic solar panels, this paper developed a new algorithm to utilize solar energy more efficiently. Since tracking solar maximum power point is a valid method to maintain the solar panel power output at a high level, at this paper, we choose ripple correlation control (RCC) to keep tracking the maximum power point of a solar photovoltaic (PV) system. Ripple correlation control is a real-time optimal method particularly suitable for power convertor control. The objective of RCC in solar PV system is to maximize the energy quantity. This paper extended the traditional analog RCC technique to the digital domain. With discretization and simplifications of math model, the RCC method can be transformed to a sampling problem. The control method shows that when the solar PV system reaches the maximum power point, power outputs at both maximum and minimum state should be nearly the same. Moreover, since voltage output of a system is easy to observe and directly related to power
2012-01-01
systems as well as vortex induced vibration systems . Section 3 presents a dynamic model of the hydrokinetic turbine system based on which a MPPT...turbines. In addition, hydrokinetic current energy can be converted into electrical energy by Vortex Induced Vibration (VIV) systems , in which a cylinder...Jiang, "Doubly- fed induction generator control for variable-speed wind power generation system ," in Proc. Mechatronics and Automation, 2009. ICMA 2009
Perez Vega, Jaime; Ponomaryov, Volodymyr [SEPI-ESIME, Mexico, D.F. (Mexico)
2000-07-01
An electronic circuit to detect the photovoltaic generator maximum power point is presented. A capacitive coupling is used as impedance to the photovoltaic generator to reflect a variable resistance effect, which makes the characteristic curve sweep possible. The power and its maximum point is determinated with electronic circuits. The power and energy losses are minimized with this method. This electronic circuit prototype is for low power and the preliminary tests were made with a 17 watts module. This project transfer and discharge to an external element or battery, which will be developed in the future. [Spanish] El presente articulo reporta el diseno de una electronica prototipo que detecta el punto de maxima potencia de un generador fotovoltaico. Esto es a partir de la utilizacion del acoplamiento de un elemento capacitivo, que actua como acoplamiento impedancia de carga hacia el generador fotovoltaico, para reflejar asi un efecto de resistencia variable, a traves de la cual se logra barrer la curva caracteristica corriente-voltaje del generador. Mediante circuitos electronicos se determina la potencia localizandose tambien el maximo punto. Con el metodo propuesto se minimiza la perdida de potencia y energia durante el proceso de localizacion de maxima potencia. La electronica desarrollada es para baja potencia a nivel prototipo, las pruebas preliminares se hicieron con un modulo de 17 wats: el circuito se encuentra en la etapa de ajuste y pruebas. Este proyecto puede ser complementado con un sistema para descargar y transferir la energia del capacitor hacia un elemento externo o bateria, el cual sera desarrollado posteriormente.
Youhua Chen
2016-09-01
Full Text Available In this report, a maximum likelihood model is developed to incorporate data uncertainty in response and explanatory variables when fitting power-law bivariate relationships in ecology and evolution. This simple likelihood model is applied to an empirical data set related to the allometric relationship between body mass and length of Sciuridae species worldwide. The results show that the values of parameters estimated by the proposed likelihood model are substantially different from those fitted by the nonlinear least-of-square (NLOS method. Accordingly, the power-law models fitted by both methods have different curvilinear shapes. These discrepancies are caused by the integration of measurement errors in the proposed likelihood model, in which NLOS method fails to do. Because the current likelihood model and the NLOS method can show different results, the inclusion of measurement errors may offer new insights into the interpretation of scaling or power laws in ecology and evolution.
Research on Maximum Power Point Tracking Method for Photovoltaic System%光伏系统中最大功率点跟踪方法的研究
郭勇; 孙超; 陈新
2009-01-01
在光伏发电系统中,光伏电池的最大输出功率取决于温度和光照条件,采用最大功率跟踪(Maximum PowerPoint Tracking,简称MPPT)方法可以使光伏电池持续输出最人功率.研究了光伏系统中的最大功率控制部分,提出了MPPT控制器的设计,介绍了几种常用的MPPT方法,其中重点研究了电导增量(Incremental Conductance,简称INC)法.给出了INC法的软件流程的设计,并在Matlab中建立了光伏电池的仿真模型.最后通过实验验证了MPPT控制器的可行性,其MPPT的响应速度和控制精度均达到了预期要求.%The maximum power point tracking(MPPT) techniques are used in photovohaic systems to maximize the photo-voltaic array output power depends on panels temperature and irradiance conditions.The part of maximum power point (MPP) for the photovoltaie system is researched.Then the system design of photovoltaic M PPT controller is proposed,some MPPT means for photovoltaic cell are introduced, focusing on the incremental conductance(INC).The software flowchart is presented and the photovohaic cell model for simulation is created in Matlab.At last,the experimental result shows the feasibility of this photovoltaic MPPT controller, the response speed and control precision meet the expectations.
Technical basis for staffing levels at nuclear power plants
Shurberg, D.A.; Haber, S.B. [Brookhaven National Lab., Upton, NY (United States); Morisseau, D. [Nuclear Regulatory Commission, Washington, DC (United States)] [and others
1995-04-01
The objective of this project is to provide a technical basis for the establishment of criteria for minimum staffing levels of licensed and non-licensed NPP shift personnel. Minimum staffing levels for the purpose of this study, are defined as those necessary for successful accomplishment of all safety and additional functions that must be performed in order for the licensee to meet applicable regulatory requirements. This project involves a multi-faceted approach to the investigation of the issue. Relevant NRC documentation was identified and reviewed. Using the information obtained from this documentation review, a test plan was developed to aid in the collection of further information regarding the adequacy of current shift staffing levels. The test plan addresses three different activities to be conducted to provide information to the NRC for use in the assessment of current minimum staffing levels. The first activity is collection of data related to industry shift staffing practices through site visits to seven nuclear power plants. The second activity is a simulator study, which will use licensed operator crews responding to a simulated event, under two different staffing levels. Finally, workload models will be constructed for both licensed and non-licensed personnel, using a priori knowledge of the simulator scenarios with data resulting from one of the staffing levels studied in the simulator, and the data collected from the site visits. The model will then be validated against the data obtained from the second staffing level studied in the simulator. The validated model can then be used to study the impact of changing staffing-related variables on the plant shift crew`s ability to effectively mitigate an event.
王琴; 姜丰; 钟清瑶
2012-01-01
The output power of photovoltaic cells changes with the external environment (light intensity, ambient temperature) and load. It is necessary to track the maximum power point of solar cell array rapidry and accurately to improve the utilizabon efficiency of solar cell array. In order to further improve the efficiency of photovoltaic power generation system, a method based on fuzzy logic dual-loop control of the maximum power point tracking of photovoltaic power generation system was presented, which added an inner loop of the fuzzy control based on the former fuzzy control. The simulation verifies that the double-loop fuzzy control method is more efficient and can effectively eliminate the oscillations around the maximum power point. The results show that this maximum power point tracking algorithm can track the maximum power point of photovoltaic power generation system rapidfy and accurately and can improve the static and dynamic performance of the photovoltaic power system.%光伏阵列的输出功率随外部环境(光照强度、环境温度)和负载的变化而变化,为充分发挥光伏器件的效能,需采用有效率的最大功率点跟踪方法.在分析光伏系统中最大功率点跟踪的问题之后,为了能够进一步提高光伏发电系统的效率和系统的稳定性,提出了一种基于模糊逻辑的双环控制的最大功率点跟踪的方法,在以往模糊控制环节的基础上再加入一个内环的模糊控制,搭建了光伏发电系统的仿真模型,通过验证表明双环模糊控制法比传统方法有更高的效率和更高的精度,并且能有效地减小系统功率损耗,且具有能同时兼顾跟踪精度和响应速度的优点.研究对比之后证实此种方法提高了系统的输出功率,保持了系统稳定,提高光伏系统MPPT控制的鲁棒性和精确性.
Nimo, Antwi; Grgic, Dario; Reindl, Leonhard M.
2012-04-01
This work presents the optimization of radio frequency (RF) to direct current (DC) circuits using Schottky diodes for remote wireless energy harvesting applications. Since different applications require different wireless RF to DC circuits, RF harvesters are presented for different applications. Analytical parameters influencing the sensitivity and efficiency of the circuits are presented. Results showed in this report are analytical, simulated and measured. The presented circuits operate around the frequency 434 MHz. The result of an L-matched RF to DC circuit operates at a maximum efficiency of 27 % at -35 dBm input. The result of a voltage multiplier achieves an open circuit voltage of 6 V at 0 dBm input. The result of a broadband circuit with a frequency band of 300 MHz, achieves an average efficiency of 5 % at -30 dBm and open circuit voltage of 47 mV. A high quality factor (Q) circuit is also realized with a PI network matching for narrow band applications.
F. Guneş
2014-04-01
Full Text Available Honey Bee Mating Optimization (HBMO is a recent swarm-based optimization algorithm to solve highly nonlinear problems, whose based approach combines the powers of simulated annealing, genetic algorithms, and an effective local search heuristic to search for the best possible solution to the problem under investigation within a reasonable computing time. In this work, the HBMO- based design is carried out for a front-end amplifier subject to be a subunit of a radar system in conjunction with a cost effective 3-D SONNET-based Support Vector Regression Machine (SVRM microstrip model. All the matching microstrip widths, lengths are obtained on a chosen substrate to satisfy the maximum power delivery and the required noise over the required bandwidth of a selected transistor. The proposed HBMO- based design is applied to the design of a typical ultra-wide-band low noise amplifier with NE3512S02 on a substrate of Rogers 4350 for the maximum output power and the noise figure F(f=1dB within the 5-12 GHz using the T- type of microstrip matching circuits. Furthermore, the effectiveness and efficiency of the proposed HBMO based design are manifested by comparing it with the Genetic Algorithm (GA, Particle Swarm Optimization (PSO and the simple HBMO based designs.
Retrieval of Intermediate Level Waste at Trawsfyndd Nuclear Power Station
Wall, S.; Shaw, I.
2002-02-25
In 1996 RWE NUKEM Limited were awarded two contracts by BNFL Magnox Generation as part of the decommissioning programme for the Trawsfynydd power station. From the normal operations of the two Magnox reactors, intermediate level waste (ILW) had accumulated on site, this was Miscellaneous Activated Components (MAC) and Fuel Element Debris (FED). The objective of these projects is retrieval of the waste from storage vaults, monitoring, packaging and immobilization in a form suitable for on site storage in the medium term and eventual disposal to a waste repository. The projects involve the design, supply, commissioning and operation of equipment to retrieve, pack and immobilize the waste, this includes recovery from vaults in both reactor and pond locations and final decommissioning and removal of plant from site after completion of waste recovery.
Rosendahl, Lasse; Mortensen, Paw Vestergård; Enkeshafi, Ali A.
2011-01-01
and market segments which are not yet quantified. This paper quantifies a micro-CHP system based on a solid oxide fuel cell (SOFC) and a high-performance TE generator. Based on a 3 kW fuel input, the hybrid SOFC implementation boosts electrical output from 945 W to 1085 W, with 1794 W available for heating......One of the most obvious early market applications for thermoelectric generators (TEG) is decentralized micro combined heat and power (CHP) installations of 0.5 kWe to 5 kWe based on fuel cell technology. Through the use of TEG technology for waste heat recovery it is possible to increase...... the electricity production in micro-CHP systems by more than 15%, corresponding to system electrical efficiency increases of some 4 to 5 percentage points. This will make fuel cell-based micro-CHP systems very competitive and profitable and will also open opportunities in a number of other potential business...
Favret, Eduardo A; Fuentes, Néstor O; Molina, Ana M; Setten, Lorena M
2008-10-01
During the last few years, RIMAPS technique has been used to characterize the micro-relief of metallic surfaces and recently also applied to biological surfaces. RIMAPS is an image analysis technique which uses the rotation of an image and calculates its average power spectrum. Here, it is presented as a tool for describing the morphology of the trichodium net found in some grasses, which is developed on the epidermal cells of the lemma. Three different species of grasses (herbarium samples) are analyzed: Podagrostis aequivalvis (Trin.) Scribn. & Merr., Bromidium hygrometricum (Nees) Nees & Meyen and Bromidium ramboi (Parodi) Rúgolo. Simple schemes representing the real microstructure of the lemma are proposed and studied. RIMAPS spectra of both the schemes and the real microstructures are compared. These results allow inferring how similar the proposed geometrical schemes are to the real microstructures. Each geometrical pattern could be used as a reference for classifying other species. Finally, this kind of analysis is used to determine the morphology of the trichodium net of Agrostis breviculmis Hitchc. As the dried sample had shrunk and the microstructure was not clear, two kinds of morphology are proposed for the trichodium net of Agrostis L., one elliptical and the other rectilinear, the former being the most suitable.
Rosendahl, L. A.; Mortensen, Paw V.; Enkeshafi, Ali A.
2011-05-01
One of the most obvious early market applications for thermoelectric generators (TEG) is decentralized micro combined heat and power (CHP) installations of 0.5 kWe to 5 kWe based on fuel cell technology. Through the use of TEG technology for waste heat recovery it is possible to increase the electricity production in micro-CHP systems by more than 15%, corresponding to system electrical efficiency increases of some 4 to 5 percentage points. This will make fuel cell-based micro-CHP systems very competitive and profitable and will also open opportunities in a number of other potential business and market segments which are not yet quantified. This paper quantifies a micro-CHP system based on a solid oxide fuel cell (SOFC) and a high-performance TE generator. Based on a 3 kW fuel input, the hybrid SOFC implementation boosts electrical output from 945 W to 1085 W, with 1794 W available for heating purposes.
Power Quality Improvement at Distribution Level for Grid Connected Renewable Energy Sources
S. Syed Ahmed
2014-09-01
Full Text Available The non-linear load current harmonics may result in voltage harmonics and can create a serious PQ problem in the power system network. Active power filters (APF are extensively used to compensate the load current harmonics and load unbalance at distribution level. This results in an additional hardware cost. However, in this project it has incorporated the features of APF in the conventional inverter interfacing renewable with the grid, without any additional hardware cost. Here, the main idea is the maximum utilization of inverter rating which is most of the time underutilized due to intermittent nature of RES. The grid-interfacing inverter can effectively be utilized to perform the four important functions they are to transfer active power harvested from the renewable resources (wind, solar, etc., load reactive power demand support, current harmonics compensation at PCC and current unbalance and neutral current compensation in case of 3-phase 4-wire system. Moreover, with adequate control of grid-interfacing inverter, all the four objectives can be accomplished either individually or simultaneously. The PQ constraints at the PCC can therefore be strictly maintained within the utility standards without additional hardware cost. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies
张俊红; 魏学业; 谷建柱; 王立华
2013-01-01
In order to improve the conversion efficiency of photovoltaic cells, this paper proposed a improved variable step size and power prediction combined with perturbation and observation method based on the mathematic model of photovoltaic array, in view of the traditional fixed step perturbation and observation method which existed the oscillation phenomenon and false phenomenon to achieve maximum power point tracking. The oscillation and misjudgment problem was eliminated by using the approximate gradient method instead of optimal gradient method and using power prediction method of multiple characteristic curves estimated on the changes in the external environment. The algorithm theory and MATLAB simulation flow chart was given in the paper. The simulation results show that the algorithm can significantly improve the tracking precision and speed of MPPT.%为了提高光伏电池的转换效率,基于光伏阵列的数学模型,针对传统的定步长扰动观察法实现最大功率点跟踪(Maximum Power Point Tracking,MPPT)时,存在的振荡现象和误判现象,提出了一种改进的变步长与功率预测相结合的扰动观察法.通过采用近似梯度法替代最优梯度法,并对外界环境发生变化时,采用功率预测的方法对多条特性曲线进行预估,来消除震荡和误判问题.本文给出了该方法的理论推导和Matlab仿真实现流程图.仿真结果表明,该方法能够显著提高MPPT的跟踪精度和速度.
Low-Carbon Based Multi-Objective Bi-Level Power Dispatching under Uncertainty
2016-01-01
This research examines a low-carbon power dispatch problem under uncertainty. A hybrid uncertain multi-objective bi-level model with one leader and multiple followers is established to support the decision making of power dispatch and generation. The upper level decision maker is the regional power grid corporation which allocates power quotas to each follower based on the objectives of reasonable returns, a small power surplus and low carbon emissions. The lower level decision makers are the...
风力发电机组最大功率追踪%Maximum Power Point Tracking for Wind Turbine
马卫东
2012-01-01
根据最大功率追踪点的基本原理及常用风力发电控制系统的特点,提出了基于占空比扰动的改进三点比较法.风力发电系统实际上应用最大功率追踪技术搭配数字信号处理器(TMS320C6711)调整DC/DC斩波器转换器的占空比,使风力发电机系统运转在最大功率输出.以1.5 kW风力发电机组为验证对象,基于TMS320C6711硬件平台对电流型扰动观察法与笔者所提出的三点比较法进行试验验证.结果表明:采用改进三点比较法的风力发电系统能够有效追踪最大功率点.同时,在风速发生变化时,能快速找到最大功率点.%According to the basic principle of maximum power point tracking(MPPT) and the characteristics of common control system for wind power conversion, a three-point comparison method based on duty cycle perturbation is presented. In the practical system implementation, the MPPT methods are integrated in the digital signal processor (DSP) TMS320C6711 to adjust the duty ratios of DC/DC chopper converter to control the generator working with maximum power output. Taking a 1.5 kW wind turbine for example, the experiment results from the TMS320C6711 based platform show that the present three-point comparison method can track the maximum power point more effectively and rapidly, compared with the conventional current-type perturbation & observation (P&0)method.
Nouws, J.F.M.; Egmond, van H.; Loeffen, G.; Schouten, J.; Keukens, H.; Smulders, I.; Stegeman, H.
1999-01-01
In this paper we assessed the suitability of the Charm HVS and a newly developed microbiological multiplate system as post-screening tests to confirm the presence of residues in raw milk at or near the maximum permissible residue level (MRL). The multiplate system is composed of Bacillus
Nouws, J.F.M.; Egmond, van H.; Loeffen, G.; Schouten, J.; Keukens, H.; Smulders, I.; Stegeman, H.
1999-01-01
In this paper we assessed the suitability of the Charm HVS and a newly developed microbiological multiplate system as post-screening tests to confirm the presence of residues in raw milk at or near the maximum permissible residue level (MRL). The multiplate system is composed of Bacillus stearotherm
Qin, Zian; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
Power fluctuation caused by wind speed variations may be harmful for the stability of the power system as well as the reliability of the wind power converter, since it may induce thermal excursions in the solder joints of the power modules. Using the wind turbine rotor inertia energy for power...... leveling has been studied before, but no quantified analysis or generic design method have been found. In this paper, the transfer functions from the wind speed to electrical power, electromagnetic torque, and rotating speed are built based on which the rotating speed controller is designed...
Comparison of leachable trace element levels in coal gasifier ash with levels in power plant ash
Bombaugh, K.J.; Milosavljevic, M.; Janes, T.K.
1984-04-01
The levels of 14 trace elements in leachates from three types of ash of a common origin coal were compared. The study was conducted over a one year period at the Kosovo plant in Obilic, Yugoslavia comparing coal gasifier ash with fly ash and bottom ash from a coal-fired power plant using lignite from the Dobro Solo mine. Results obtained indicate that levels of Sb, As, Be, Cr, Cu, Pb, Mo, Ni and Zn in gasifier ash leachate were similar to those in fly ash leachate. Barium levels in gasifier ash leachate averaged 2.7 times that in fly ash and selenium levels averaged 0.33 times. The average ratio for the total set was 0.99. The set average, relative to bottom ash, was 2.1 with the nickel ratio differing significantly from the average. Metal oxides, CaO, MgO, Na/SUB/2O, K/SUB/2O and MgO; in the Kosovo gasifier ash were found at levels similar to those in Kosovo fly ash, and except for K/SUB/2O, were approximately twice those in bottom ash. Concentration levels of all components showed relatively small variations averaging 50% of their mean annual concentration over the test period. (14 refs.)
Gabriel Filho, Luis Roberto Almeida [Universidade Estadual Paulista (CE/UNESP), Tupa, SP (Brazil). Campus Experimental. Curso de Administracao], E-mail: gabrielfilho@tupa.unesp.br; Cremasco, Camila Pires [Faculdade de Tecnologia de Presidente Prudente (FATEC), SP (Brazil). Curso Tecnologia em Agronegocio], E-mail: camila@fatec.edu.br; Seraphim, Odivaldo Jose [Universidade Estadual Paulista (FCA/UNESP), Botucatu, SP (Brazil). Fac. de Ciencias Agronomicas. Dept. de Engenharia Rural], E-mail: seraphim@fca.unesp.br
2010-07-01
The Earth receives annually 1,5.1018 kWh of solar energy, which corresponds to 1000 times the world energy consumption in this period. This fact comes out that, besides being responsible for the maintenance of life on Earth, the solar radiation is in an inexhaustible energy source, with an enormous potential for use by systems capture and conversion into another form of energy. In many applications of low power systems that convert light directly into electricity, called photovoltaic advantageously replace other means of production processes, where its distribution is very significant. The determination of the power generated by such a system is of paramount importance for the design energy of its implementation and evaluation of the system itself. This study aims to determine a relationship between the maximum power generated by solar photovoltaic and characteristic parameters of the generator. This relationship allows to evaluate the performance of such a system. For simulations of the developed equations were used 3 photovoltaic modules with an output of 100 Wp each, and data collection was performed during one year by enrolling in addition to meteorological data, solar irradiance incident on the modules. (author)
Regina A. A.; I. Mohammad Halim Shah
2010-01-01
The study is to model emission from a stack to estimate ground level concentration from a palm oil mill. The case study is a mill located in Kuala Langat, Selangor. Emission source is from boilers stacks. The exercise determines the estimate the ground level concentrations for dust to the surrounding areas through the utilization of modelling software. The surround area is relatively flat, an industrial area surrounded by factories and with palm oil plantations in the outskirts. The model uti...
Research on network maximum flows algorithm of cascade level graph%级连层次图的网络最大流算法研究
潘荷新; 伊崇信; 李满
2011-01-01
给出一种通过构造网络级连层次图的方法,来间接求出最大网络流的算法.对于给定的有n个顶点,P条边的网络N=(G,s,t,C),该算法可在O(n2)时间内快速求出流经网络N的最大网络流及达最大流时的网络流.%This paper gives an algoritm that structures a network cascade level graph to find out maximum flow of the network indirectly.For the given network N=(G,s,t,C) that has n vetexes and e arcs,this algorithm finds out the maximum value of the network flow fast in O(n2) time that flows from the network N and the network flows when the value of the one reach maximum.
Vescovi, Jason D
2014-07-01
The aim of this study was to examine the impact of maximum sprint speed on peak and mean sprint speed during youth female field hockey matches. Two high-level female field hockey teams (U-17, n = 24, and U-21, n = 20) were monitored during a 4-game international test series using global position system technology and tested for maximum sprint speed. Dependent variables were compared using a 3-factor ANOVA (age group, position, and speed classification); effect sizes (Cohen d) and confidence limits were also calculated. Maximum sprint speed was similar between age groups and positions, with faster players having greater speed than slower players (29.3 ± 0.4 vs 27.2 ± 1.1 km/h). Overall, peak match speed in youth female field hockey players reaches approximately 90% of maximum sprint speed. Absolute peak match speed and mean sprint speed during matches were similar among the age groups (except match 1) and positions (except match 2); however, peak match speed was greater for faster players in matches 3 and 4. No differences were observed in the relative proportion for mean sprint speeds for age groups or positions, but slower players consistently displayed similar relative mean sprint speeds by using a greater proportion of their maximum sprint speed.
Senju, T.; Uezato, K. [Univ. of the Ryukyus, Okinawa (Japan). College of Engineering; Tokumura, M. [Okinawa Electric Power Co. Inc., Okinawa (Japan)
1995-09-30
In recent years, exploitation of natural energy by saving fossil energy is being reconsidered. One of the expected sources of natural energy for the future is wind energy, which has been actively studied as a substitute energy for the world. However, wind energy is influenced by geographic and weather conditions, so the generating power varies with time. Therefore, in order to make the windmill generator system to extract available maximumpower from wind energy, this paper proposes a tracking control method of maximum power operating point using the recursively least square method with forgetting factor. The proposed method is simple since it identifies mechanical parameters and it controls the actual rotor speed by means of a PI controller. System parameters are identified by using generator power and windmill speed. Simulation and experiment results verify the effectiveness of the proposed control method. 8 refs., 57 figs., 11 tabs.
Regina A. A.
2010-12-01
Full Text Available The study is to model emission from a stack to estimate ground level concentration from a palm oil mill. The case study is a mill located in Kuala Langat, Selangor. Emission source is from boilers stacks. The exercise determines the estimate the ground level concentrations for dust to the surrounding areas through the utilization of modelling software. The surround area is relatively flat, an industrial area surrounded by factories and with palm oil plantations in the outskirts. The model utilized in the study was to gauge the worst-case scenario. Ambient air concentrations were garnered calculate the increase to localized conditions. Keywords: emission, modelling, palm oil mill, particulate, POME
Kinkhabwala, Ali
2013-01-01
The most fundamental problem in statistics is the inference of an unknown probability distribution from a finite number of samples. For a specific observed data set, answers to the following questions would be desirable: (1) Estimation: Which candidate distribution provides the best fit to the observed data?, (2) Goodness-of-fit: How concordant is this distribution with the observed data?, and (3) Uncertainty: How concordant are other candidate distributions with the observed data? A simple unified approach for univariate data that addresses these traditionally distinct statistical notions is presented called "maximum fidelity". Maximum fidelity is a strict frequentist approach that is fundamentally based on model concordance with the observed data. The fidelity statistic is a general information measure based on the coordinate-independent cumulative distribution and critical yet previously neglected symmetry considerations. An approximation for the null distribution of the fidelity allows its direct conversi...
Tran Duy, A.; Smit, B.; Dam, van A.A.; Schrama, J.W.
2008-01-01
The aim of this study was to gain insight into how Nile tilapia (Oreochromis niloticus) regulate feed and energy intake in response to diets low and high in starch and cellulose. It was hypothesized that high-starch diets would reduce feed intake due to the effect of high blood glucose level, and th
Thompson, William L.; Lee, Danny C.
2000-11-01
Many anadromous salmonid stocks in the Pacific Northwest are at their lowest recorded levels, which has raised questions regarding their long-term persistence under current conditions. There are a number of factors, such as freshwater spawning and rearing habitat, that could potentially influence their numbers. Therefore, we used the latest advances in information-theoretic methods in a two-stage modeling process to investigate relationships between landscape-level habitat attributes and maximum recruitment of 25 index stocks of chinook salmon (Oncorhynchus tshawytscha) in the Columbia River basin. Our first-stage model selection results indicated that the Ricker-type, stock recruitment model with a constant Ricker a (i.e., recruits-per-spawner at low numbers of fish) across stocks was the only plausible one given these data, which contrasted with previous unpublished findings. Our second-stage results revealed that maximum recruitment of chinook salmon had a strongly negative relationship with percentage of surrounding subwatersheds categorized as predominantly containing U.S. Forest Service and private moderate-high impact managed forest. That is, our model predicted that average maximum recruitment of chinook salmon would decrease by at least 247 fish for every increase of 33% in surrounding subwatersheds categorized as predominantly containing U.S. Forest Service and privately managed forest. Conversely, mean annual air temperature had a positive relationship with salmon maximum recruitment, with an average increase of at least 179 fish for every increase in 2 C mean annual air temperature.
EMERSON DE OLIVEIRA GHERI
2000-09-01
Full Text Available Foram avaliados os efeitos da aplicação de fósforo (P em solo argiloso, de textura média e arenoso, sobre a produção de matéria seca de Panicum maximum Jacq. cv. Tanzânia. O ensaio foi conduzido em casa de vegetação, em vasos de plástico contendo 10 dm³ de solo, em esquema fatorial e delineamento inteiramente ao acaso. Após calagem para V = 70% e aplicação de 0, 35, 70, 105 e 140 mg/dm³ de P, o solo foi umedecido, e depois de 30 dias, secado e amostrado. O ensaio foi conduzido por 76 dias, a partir da emergência das plântulas, com o primeiro corte aos 48 dias, a 10 cm do solo, e o segundo, aos 76,rente ao solo. Com a aplicação de P houve aumento de produção de matéria seca, e o maior acréscimo ocorreu com a aplicação de 35 mg/dm³. A maior produção foi obtida no solo de textura média. O teor de P nas plantas estava adequado nos solos arenoso e argiloso. No de textura média, ele diminuiu com o aumento da produção,caracterizando efeito de diluição. Com aprodução relativa e o teor de P de cada solo, foi determinado o nível crítico de 38 mg/dm³ de P extraído por resina.A greenhouse experiment was carried out to evaluate the effects of phosphorus (P application on dry matter production of Panicum maximum Jacq. cv. Tanzânia. The experimental design was completely randomized, in outline complete factorial combining three soils with different textures (sandy, middle, clay and five P levels: 0, 35, 70, 105 and 140 mg/dm³. After liming to elevate base saturation degree to 70% and P application, the soils were moistened and after 30 days they were dried and sampled. Plastic pots with 10 dm³ soil were used and the grass grew for 76 days. In this period two cuts were made: the first one, at 10 cm above soil, 48 days after emergency, and the second, 76 days after the first one, at the soil surface. The dry matter production increased with P application for the three soils and the maximum increase was observed with 35
Power Grid Construction Project Portfolio Optimization Based on Bi-level programming model
Zhao, Erdong; Li, Shangqi
2017-08-01
As the main body of power grid operation, county-level power supply enterprises undertake an important emission to guarantee the security of power grid operation and safeguard social power using order. The optimization of grid construction projects has been a key issue of power supply capacity and service level of grid enterprises. According to the actual situation of power grid construction project optimization of county-level power enterprises, on the basis of qualitative analysis of the projects, this paper builds a Bi-level programming model based on quantitative analysis. The upper layer of the model is the target restriction of the optimal portfolio; the lower layer of the model is enterprises’ financial restrictions on the size of the enterprise project portfolio. Finally, using a real example to illustrate operation proceeding and the optimization result of the model. Through qualitative analysis and quantitative analysis, the bi-level programming model improves the accuracy and normative standardization of power grid enterprises projects.
Guzman, Eusebio; Mendoza, Victor X; Carrillo, Jose J . A; Galarza, Cristian [Universidad Autonoma Metropolitana, Mexico, D.F. (Mexico)
2000-07-01
A maximum power point tracker MPPT for photovoltaic systems is presented. The equipment can output up to 600 W and its control signals are generated by a PIC microcontroller. The principle of control is based on current and voltage sampling at the output terminals of the photovoltaic generator. From power comparison of two consecutive samples, it is possible to know how far from the optimal point the system is working. Output voltage control is used to force the system to work within the optimal area of operation. The microcontroller program sequence, the DC/DC converter structure and the most relevant results are shown. [Spanish] En este trabajo se presenta el desarrollo de un controlador de potencia maxima para su aplicacion en sistemas fotovoltaicos (SFVs). El diseno alcanza una potencia de 600 W y sus senales de control son generadas con un controlador PIC. El principio de control se basa en el muestreo de la corriente y la tension en las terminadas del generador fotovoltaico GFV. De dos muestreos consecutivos, y por comparacion de las potencias, se determina que tan alejado del punto optimo opera el sistema. La operacion del sistema dentro de la zona de funcionamiento optimo se asegura mediante un control por tension. Se muestra la secuencia de programacion del microcontrolador, la estructura del convertidor CD/CD empleado y algunos resultados relevantes.
一种新型的光伏发电最大功率跟踪方法研究%A new photovoltaic power generation maximum power tracking method
赵立永; 黄成玉; 邓永红
2013-01-01
In order to find a better photovoltaic power generation system maximum power point tracking control method,according to the internal structure and volt-ampere characteristic of solar battery,the solar cell of the equivalent circuit was established.MATLAB language was used to establish the solar panels simulation model.In the analysis of the existing maximum power tracking method,a new type of MPPT tracking method was put forward,called improved voltage increment method,the mathematics model of the method was established,and MATLAB was used to simulate the experiment.The simulation results show that this method can make the most high power tracking faster and more accurate,and through the later stage grid inverter control,the low harmonic content and high power factor requirements is realized.%为了寻找更好的实现光伏发电系统最大功率点追踪控制方法,根据太阳电池的内部结构和伏安特性建立了太阳电池的等效电路,利用MATLAB语言建立了太阳电池板仿真模型.在分析已有最大功率追踪方法的基础上,提出了一种新型的MPPT跟踪方法——改进的电压增量法,建立了该方法的数学模型,并利用MATLAB进行了仿真实验.仿真实验结果表明该方法使最大功率跟踪更快更准,并通过对后级并网逆变器的控制实现了低谐波含量、高功率因数的并网要求.
Cognitive Aspects of Power in a Two-Level Game
Juvina, Ion; Lebiere, Christian; Martin, Jolie; Gonzalez, Cleotilde
The Intergroup Prisoner's Dilemma with Intragroup Power Dynamics (IPD^2) is a new game paradigm for studying human behavior in conflict situations. IPD^2 adds the concept of intragroup power to an intergroup version of the standard Iterated Prisoner's Dilemma game. We conducted an exploratory laboratory study in which individual human participants played the game against computer strategies of various complexities. We also developed a cognitive model of human decision making in this game. The model was run in place of the human participant under the same conditions as in the laboratory study. Results from the human study and the model simulations are presented and discussed, emphasizing the value of including intragroup power in game theoretic models of conflict.
European Food Safety Authority
2013-05-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance ethoxyquin. Although this active substance is no longer authorised within the European Union, an MRL was established by the Codex Alimentarius Commission (CXL. Based on the assessment of the available data, EFSA assessed the CXL, and a consumer risk assessment was carried out. The CXL was found not to be adequately supported by data and a possible risk to consumers was identified. Hence, further consideration by risk managers is needed.
European Food Safety Authority
2014-07-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance indolylbutyric acid. Considering that this active substance is not authorised for use on edible crops within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of indolylbutyric acid are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or a limit of quantification (LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-07-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance acetochlor. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of acetochlor are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-05-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance cyanamide. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of cyanamide are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-04-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance trifluralin. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of trifluralin are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-05-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance asulam. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of asulam are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-06-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance dicloran. Although this active substance is no longer authorised within the European Union, MRLs were established by the Codex Alimentarius Commission (CXLs. Based on the assessment of the available data, EFSA assessed the CXLs, and a consumer risk assessment was carried out. Some CXLs were found not to be adequately supported by data and, for some CXLs, a possible acute risk to consumers was also identified. Hence, further consideration by risk managers is needed.
European Food Safety Authority
2013-03-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance quinoclamine. Considering that this active substance is not authorised for use on edible crops within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of quinoclamine are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-05-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance guazatine. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of guazatine are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-08-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance propargite. Although this active substance is no longer authorised within the European Union, MRLs were established by the Codex Alimentarius Commission (CXLs. Based on the assessment of the available data, EFSA assessed the CXLs. CXLs were found not to be adequately supported by data and a consumer risk assessment could not be carried out. Hence, further consideration by risk managers is needed.
European Food Safety Authority
2013-05-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance 1,3-dichloropropene. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of 1,3-dichloropropene are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2014-05-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance dodemorph. Considering that this active substance is not authorised for use on edible crops within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of dodemorph are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2014-07-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance indolylacetic acid. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of indolylacetic acid are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or a limit of quantification (LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-07-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance chloropicrin. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of chloropicrin are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
European Food Safety Authority
2013-06-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance propisochlor. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of propisochlor are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.
Federal Institute for Risk Assessment
2015-01-01
Rice and rice-based products, such as rice cakes or rice flakes for creamed rice, can contain relatively high levels of inorganic arsenic. Inorganic arsenic is classified as carcinogenic for humans by international panels and no intake quantity can be defined as safe for human health with regard to its carcinogenic effect (cf. BfR opinion 018/2015). In the European Union, the introduction of maximum levels for inorganic arsenic in rice and rice products is being discussed on the basis of the ...
The development of a milliwatt-level radioisotope power source
Bugby, David C.; McBirney, Thomas R.
1998-01-01
Future NASA spacecraft for unmanned planetary exploration will be much smaller and require much less power than the large systems used in prior missions. The ``Powerstick'', a miniaturized isotopic electrical power generator, uses a flight-qualified, DoE-manufactured, 1.1 W Radioisotope Heater Unit (RHU) to generate the high temperature sink for a thermoelectric converter (TEC). The TEC generates sufficient electrical power (~40 mW) to trickle-charge an external rechargeable battery pack, which can then be used in low duty cycle, low power applications. The original Powerstick concept (proposed by JPL) was refined at Swales Aerospace (SA), which has: repackaged it, constructed a prototype, and performed limited testing. The prototype Powerstick is 63.5 mm (2.500'') in diameter, 76.2 mm (3.000'') long, and weighs about 0.3 kg (0.66 lb). Structural analysis indicates the Powerstick can easily survive typical launch loads. Thermal analysis indicates that over 70% of the RHU energy enters the TEC. This paper will describe the design and analysis of the Powerstick prototype and present the key test results.
Module-Level Power Converters For Parallel Connected Photovoltaic Arrays
2012-01-01
Secondary Bare Wire Area Rs Secondary Resistance Ps Secondary Copper Loss Pcu Total Copper Loss W/kg Watts Per Kilogram Pfe Core Loss PΣ Total...material properties of the chosen core [30]. The calculated core loss power density was was 17.2712 W/kg. The core loss, Pfe , was calculated
Early Experiences with Node-Level Power Capping on the Cray XC40 Platform
Pedretti, Kevin; Olivier, Stephen Lecler; Ferreira, Kurt Brian; Shipman, Galen; Shu, Wei
2015-10-01
Power consumption of extreme-scale supercomputers has become a key performance bottleneck. Yet current practices do not leverage power management opportunities, instead running at ''maximum power''. This is not sustainable. Future systems will need to manage power as a critical resource, directing where it has greatest benefit. Power capping is one mechanism for managing power budgets, however its behavior is not well understood. This paper presents an empirical evaluation of several key HPC workloads running under a power cap on a Cray XC40 system, and provides a comparison of this technique with p-state control, demonstrating the performance differences of each. These results show: 1. Maximum performance requires ensuring the cap is not reached; 2. Performance slowdown under a cap can be attributed to cascading delays which result in unsynchronized performance variability across nodes; and, 3. Due to lag in reaction time, considerable time is spent operating above the set cap. This work provides a timely and much needed comparison of HPC application performance under a power cap and attempts to enable users and system administrators to understand how to best optimize application performance on power-constrained HPC systems.
The advantages and disadvantages of centralized control of air power at operational level
Arisoy, Uǧur
2014-05-01
People do not want to see and hear a war. In today's world, if war is inevitable, the use of air power is seen as the preferable means of conducting operations instead of financially burdensome land battles which are more likely to cause heavy loss of life. The use of Air Power has gained importance in NATO operations in the Post-Cold War era. For example, air power has undertaken a decisive role from the beginning to the end of the operation in Libya. From this point of view, the most important issue to consider is how to direct air power more effectively at operational level. NATO's Core JFAC (Joint Force Air Command) was established in 2012 to control joint air power at operational level from a single center. US had experienced JFAC aproach in the Operation Desert Storm in 1991. UK, France, Germany, Italy and Spain are also directing their air power from their JFAC structures. Joint air power can be directed from a single center at operational level by means of JFAC. JFAC aproach provides complex planning progress of Air Power to be controled faster in a single center. An Air Power with a large number of aircrafts, long range missiles of cutting-edge technology may have difficulties in achieving results unless directed effectively. In this article, directing air power more effectively at operational level has been studied in the framework of directing air power from a single center carried out by SWOT analysis technique. "Directing Air Power at operational level from a single center similar to JFAC-like structure" is compared with "Directing Air Power at operational level from two centers similar to AC (Air Command) + CAOC (Combined Air Operations Center) structure" As a result of this study, it is assessed that directing air power at operational level from a single center would bring effectiveness to the air campaign. The study examines directing air power at operational level. Developments at political, strategic and tactical levels have been ignored.
Karlsson, J S; Ostlund, N; Larsson, B; Gerdle, B
2003-10-01
Frequency analysis of myoelectric (ME) signals, using the mean power spectral frequency (MNF), has been widely used to characterize peripheral muscle fatigue during isometric contractions assuming constant force. However, during repetitive isokinetic contractions performed with maximum effort, output (force or torque) will decrease markedly during the initial 40-60 contractions, followed by a phase with little or no change. MNF shows a similar pattern. In situations where there exist a significant relationship between MNF and output, part of the decrease in MNF may per se be related to the decrease in force during dynamic contractions. This study estimated force effects on the MNF shifts during repetitive dynamic knee extensions. Twenty healthy volunteers participated in the study and both surface ME signals (from the right vastus lateralis, vastus medialis, and rectus femoris muscles) and the biomechanical signals (force, position, and velocity) of an isokinetic dynamometer were measured. Two tests were performed: (i) 100 repetitive maximum isokinetic contractions of the right knee extensors, and (ii) five gradually increasing static knee extensions before and after (i). The corresponding ME signal time-frequency representations were calculated using the continuous wavelet transform. Compensation of the MNF variables of the repetitive contractions was performed with respect to the individual MNF-force relation based on an average of five gradually increasing contractions. Whether or not compensation was necessary was based on the shape of the MNF-force relationship. A significant compensation of the MNF was found for the repetitive isokinetic contractions. In conclusion, when investigating maximum dynamic contractions, decreases in MNF can be due to mechanisms similar to those found during sustained static contractions (force-independent component of fatigue) and in some subjects due to a direct effect of the change in force (force-dependent component of fatigue
Deconstructing the power resistance relationship for squats: A joint-level analysis.
Farris, D J; Lichtwark, G A; Brown, N A T; Cresswell, A G
2016-07-01
Generating high leg power outputs is important for executing rapid movements. Squats are commonly used to increase leg strength and power. Therefore, it is useful to understand factors affecting power output in squatting. We aimed to deconstruct the mechanisms behind why power is maximized at certain resistances in squatting. Ten male rowers (age = 20 ± 2.2 years; height = 1.82 ± 0.03 m; mass = 86 ± 11 kg) performed maximal power squats with resistances ranging from body weight to 80% of their one repetition maximum (1RM). Three-dimensional kinematics was combined with ground reaction force (GRF) data in an inverse dynamics analysis to calculate leg joint moments and powers. System center of mass (COM) velocity and power were computed from GRF data. COM power was maximized across a range of resistances from 40% to 60% 1RM. This range was identified because a trade-off in hip and knee joint powers existed across this range, with maximal knee joint power occurring at 40% 1RM and maximal hip joint power at 60% 1RM. A non-linear system force-velocity relationship was observed that dictated large reductions in COM power below 20% 1RM and above 60% 1RM. These reductions were due to constraints on the control of the movement.
Photovoltaic Shading Testbed for Module-Level Power Electronics
Deline, C.; Meydbray, J.; Donovan, M.; Forrest, J.
2012-05-01
This document describes a repeatable test procedure that attempts to simulate shading situations, as would be experienced by typical residential rooftop photovoltaic (PV) systems. This type of shading test is particularly useful to evaluate the impact of different power conversion setups, including microinverters, DC power optimizers and string inverters, on overall system performance. The performance results are weighted based on annual estimates of shade to predict annual performance improvement. A trial run of the test procedure was conducted with a side by side comparison of a string inverter with a microinverter, both operating on identical 8kW solar arrays. Considering three different shade weighting conditions, the microinverter was found to increase production by 3.7% under light shading, 7.8% under moderate shading, and 12.3% under heavy shading, relative to the reference string inverter case. Detail is provided in this document to allow duplication of the test method at different test installations and for different power electronics devices.
On the Wind Stress - Sea Level Power Law.
1983-06-01
The response of coastal sea level to local forcing by synpotic scale winds is usually assumed to be linear in wind stress . However, the response of...response to wind stress may allow significant improvement in the analysis of some sea-level problems. (Author)
Simpson, Matthew J. R.; Milne, Glenn A.; Huybrechts, Philippe; Long, Antony J.
2009-08-01
We constrain a three-dimensional thermomechanical model of Greenland ice sheet (GrIS) evolution from the Last Glacial Maximum (LGM, 21 ka BP) to the present-day using, primarily, observations of relative sea level (RSL) as well as field data on past ice extent. Our new model (Huy2) fits a majority of the observations and is characterised by a number of key features: (i) the ice sheet had an excess volume (relative to present) of 4.1 m ice-equivalent sea level at the LGM, which increased to reach a maximum value of 4.6 m at 16.5 ka BP; (ii) retreat from the continental shelf was not continuous around the entire margin, as there was a Younger Dryas readvance in some areas. The final episode of marine retreat was rapid and relatively late (c. 12 ka BP), leaving the ice sheet land based by 10 ka BP; (iii) in response to the Holocene Thermal Maximum (HTM) the ice margin retreated behind its present-day position by up to 80 km in the southwest, 20 km in the south and 80 km in a small area of the northeast. As a result of this retreat the modelled ice sheet reaches a minimum extent between 5 and 4 ka BP, which corresponds to a deficit volume (relative to present) of 0.17 m ice-equivalent sea level. Our results suggest that remaining discrepancies between the model and the observations are likely associated with non-Greenland ice load, differences between modelled and observed present-day ice elevation around the margin, lateral variations in Earth structure and/or the pattern of ice margin retreat.
李鑫; 方陈; 张沛超; 包海龙
2013-01-01
For common maximum power point tracking (MPPT) control methods, the complexities of the structures and the controlling effects cannot be balanced very well. Aiming at this problem, an argumentation about the application of maximum power transmission theorytransfer?theorem in the PV system is discussed and a solution onfrom the view of impedance adaption is presented. According to the conclusion, a new MPPT control algorithm, which has the ability of rapid self-optimization, was proposed. The simulation model of three-phase grid-connected PV power system is established through MATLAB/Simulink. And the experiment is implemented under the circumstances such as? fast changes of external environments and load fluctuation. Comparing the improved control method with some classic ones, the results indicate that the tracking effect of proposed improved impedance adaption algorithm is better.%针对光伏发电系统最大功率点跟踪控制中结构复杂度与控制效果难以兼得的问题,文章从阻抗适配角度论证了最大功率传输理论应用于光伏系统控制的正确性,并提出一种具备快速自寻优能力的光伏系统最大功率点跟踪控制方法.通过Matlab仿真并与常见最大功率点跟踪控制方法相比较,文章所提出的算法具有更好的跟踪效果.
European Food Safety Authority
2014-04-01
Full Text Available EFSA was requested by the European Commission to perform a dietary exposure assessment for the proposed temporary maximum residue levels (MRLs for didecyldimethylammonium chloride (DDAC and benzalkonium chloride (BAC (0.1 mg/kg, respectively, for all food commodities covered by the EU MRL legislation. Based on the information, EFSA did not identify potential consumer health risks for these proposed MRLs. Thus, the proposed MRLs are considered to be sufficiently protective. However, due to the limited data available, the risk assessments are affected by a high degree of uncertainty.
Level shifter for low power applications with body bias technique
user
With the rapid growth in high speed computation and battery operated devices like ... consideration for integrated circuits includes size, propagation delay, throughput ..... A new level-up shifter for high speed and wide range interface in ultra.
E. P. Zabello
2005-01-01
Full Text Available The method is proposed to make a correction in payment for consumption of reactive energy and power which is attributed to deviation of actual activation energy losses for reactive power compensation from their standard value. It is recommended to calculate standard loss values for every voltage level and actual loss values are to be determined with the help of application of remote electronic accounting means in the current mode of power consumption.
Toward the Next Level of PCB Usage in Power Electronic Converters
De Jong, E.C.W.; Ferreira, B.J.A.; Bauer, P.
2008-01-01
A means for power electronics to exploit the level of 3-D packaging already being implemented in compact consumer products, such as digital cameras, is investigated in order to increase its power density. The increase in functionality and usage of printed circuit board (PCB) in power electronic conv
System-level Reliability Assessment of Power Stage in Fuel Cell Application
Zhou, Dao; Wang, Huai; Blaabjerg, Frede
2016-01-01
the lifetime model and the stress levels, the Weibull distribution of the power semiconductors lifetime can be obtained by using Monte Carlo analysis. Afterwards, the reliability block diagram can further be adopted to evaluate the reliability of the power stage based on the estimated power semiconductor...
丁明; 刘盛
2013-01-01
The random fluctuation and Intermittency of photovoltaic (PV) generation system bring obvious affection on power grid. The higher the capacity of PV generation system, the more obvious the affection will be. A genetic algorithm (GA) based approach for the calculation of maximum penetration level of multi PV generations simultaneously connected to distribution network is proposed. In the proposed approach, the abrupt change of output of PV generations in distribution network and the condition that on-load tap changer (OLTC) and shunt capacitor participate in voltage regulation are taken into account. To verify the effectiveness of the proposed method, IEEE 33-bus test system is taken for example and calculation results show that the network-connected positions of PV generations, load level of the test system and power factors of PV generations evidently affect the maximum penetration level of multi PV generations.% 光伏电站出力具有随机波动性和间歇性，给电网带来很大的影响，且容量越大，影响越显著。提出了基于遗传算法求解多个光伏电源同时接入配电网的极限功率的计算方法。该方法考虑了配电网中光伏电源出力突变以及有载调压变压器和并联电容器参与调压的情况。以IEEE33测试系统为例，分析了光伏电源接入位置、电网负荷水平以及光伏电源功率因数对极限功率的影响，验证了该方法的有效性。
Power Analysis for Cross Level Mediation in CRTs
Kelcey, Ben
2014-01-01
A common design in education research for interventions operating at a group or cluster level is a cluster randomized trial (CRT) (Bloom, 2005). In CRTs, intact clusters (e.g., schools) are assigned to treatment conditions rather than individuals (e.g., students) and are frequently an effective way to study interventions because they permit…
Operating the Irish power system with increased levels of wind power
Tuohy, A.; Denny, E.; Meibom, Peter
2008-01-01
This paper summarises some of the main impacts of large amounts of wind power installed in the island of Ireland. Using results from various studies performed on this system, it is shown that wind power will impact on all time frames, from seconds to daily planning of the system operation. Results...... from studies examining operation of the system with up to approximately 40% of electricity provided by wind show that some of the most important aspects to be considered include the type of wind turbine technology, the provision of reserve to accommodate wind forecasting error and the method used...
Power levels in office equipment: Measurements of new monitors and personal computers
Roberson, Judy A.; Brown, Richard E.; Nordman, Bruce; Webber, Carrie A.; Homan, Gregory H.; Mahajan, Akshay; McWhinney, Marla; Koomey, Jonathan G.
2002-05-14
Electronic office equipment has proliferated rapidly over the last twenty years and is projected to continue growing in the future. Efforts to reduce the growth in office equipment energy use have focused on power management to reduce power consumption of electronic devices when not being used for their primary purpose. The EPA ENERGY STAR[registered trademark] program has been instrumental in gaining widespread support for power management in office equipment, and accurate information about the energy used by office equipment in all power levels is important to improving program design and evaluation. This paper presents the results of a field study conducted during 2001 to measure the power levels of new monitors and personal computers. We measured off, on, and low-power levels in about 60 units manufactured since July 2000. The paper summarizes power data collected, explores differences within the sample (e.g., between CRT and LCD monitors), and discusses some issues that arise in m etering office equipment. We also present conclusions to help improve the success of future power management programs.Our findings include a trend among monitor manufacturers to provide a single very low low-power level, and the need to standardize methods for measuring monitor on power, to more accurately estimate the annual energy consumption of office equipment, as well as actual and potential energy savings from power management.
European Food Safety Authority
2013-05-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance dichlobenil. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of dichlobenil are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses for the time being but this assessment may be reconsidered when the future review of MRLs for fluopicolide under the aforementioned regulation (EC No 396/2005 will be carried out because fluopicolide is an authorised pesticide active substance generating a metabolite common to dichlobenil.
European Food Safety Authority
2014-01-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance kresoxim-methyl. In order to assess the occurrence of kresoxim-methyl residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2014-01-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance fenhexamid. In order to assess the occurrence of fenhexamid residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2014-07-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance boscalid. In order to assess the occurrence of boscalid residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and all MRL proposals derived by EFSA still require further consideration by risk managers
European Food Safety Authority
2013-09-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance flutolanil. In order to assess the occurrence of flutolanil residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still requires further consideration by risk managers.
European Food Safety Authority
2012-10-01
Full Text Available
According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance etoxazole. In order to assess the occurrence of etoxazole residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2014-02-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance trifloxystrobin. In order to assess the occurrence of trifloxystrobin residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2013-12-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance azoxystrobin. In order to assess the occurrence of azoxystrobin residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances andEuropean authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2014-05-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance folpet. In order to assess the occurrence of folpet residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2014-04-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance teflubenzuron. In order to assess the occurrence of teflubenzuron residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2012-11-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance fenamidone. In order to assess the occurrence of fenamidone residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2013-01-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance metsulfuron-methyl. In order to assess the occurrence of metsulfuron-methyl residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2014-07-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance thiabendazole. In order to assess the occurrence of thiabendazole residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and all MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2012-12-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance flurtamone. In order to assess the occurrence of flurtamone residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. No information required by the regulatory framework was found to be missing and no risk to consumers was identified.
European Food Safety Authority
2012-11-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance carfentrazone-ethyl. In order to assess the occurrence of carfentrazone-ethyl residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and all MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2013-02-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide acibenzolar-S-methyl. In order to assess the occurrence of acibenzolar-S-methyl residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2012-11-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance mesosulfuron. In order to assess the occurrence of mesosulfuron residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. No information required by the regulatory framework was found to be missing and no risk to consumers was identified.
European Food Safety Authority
2012-12-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide cyazofamid. In order to assess the occurrence of cyazofamid residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
The far-reaching effects of power: at the individual, dyadic, and group levels
Galinsky, A.D.; Chou, E.Y.; Halevy, N.; Van Kleef, G.A.; Neale, M.A.; Mannix, E.A.
2012-01-01
Purpose - This chapter provides a framework that captures the fundamental impacts of power at the individual, dyadic, small group, and organizational levels. Within each level, we trace the psychological, cognitive, and behavioral consequences of having or lacking power. Approach - We integrate theo
Study on maximum power point tracking control techniques in PV system%光伏系统最大功率点跟踪技术研究
韦世宽; 雷加; 谈恩民; 王冬
2011-01-01
Maximum power point tracking (MPPT) technologies and their applications were classified based on the differences of control algorithms with three typical methods analyzed, i.e.constant voltage algorithm, the perturb and observe algorithm and incremental conductance algorithm. The control principle for each method was analyzed. Experiments based on flyback converter were made to verify the feasibility and performance of the methods. The characteristics of each method were obtained, including the starting time, dynamic response and steady state accuracy. Finally, a combining constant voltage algorithms with incremental conductance algorithm is proposed, which applies in practical applications. The algorithm has quickly dynamic response and highly steady state accuracy.%针对目前光伏最大功率点跟踪(MPPT)技术研究和应用现状,根据控制算法的不同分类,选取固定电压法、扰动观察法、增量电导法作为研究对象.分析各种控制算法的实现原理,并且在反激式变换器上进行试验验证,对试验结果进行比较分析,得出三种MPPT控制方法在启动时间、动态响应、稳态控制精度等方面的性能,本文最后提出一种在实际应用中能够达到良好控制效果的固定电压启动结合增量电导算法,该算法动态响应快、稳态控制精度高.
林躜; 李磊; 陈俊华; 郑堤; 唐辰; 李浩
2014-01-01
In order to solve the problem of low energy capturing efficiency of the horizontal axis turbine in tidal current power generation system at low current speed, a variable pump counter torque reference value model was established. In this study, based on the maximum power tracking theory and the torque equilibrium equation of turbine versus variable pump, a control system with indirect speed control, pressure feedback, and torque control was designed to achieve the maximum power capture of the turbine by regulating the output of the variable pump in a small range. The performance of the designed control system was simulated by means of the Automation Studio software, and corresponding sea test was conducted. Test results showed that the control system ran steadily, the captured power coefficient of the turbine fluctuated near 0.35 and 0.33, respectively, in the simulation and sea trials; compared with the uncontrolled, these numbers increased by 0.03 and 0.05, respectively. The capture efficiency of the turbine was enhanced, and the effectiveness of the control system was verified.%文章为解决水平轴潮流能发电系统在低于设计流速下叶轮能量捕获效率低的问题,运用最大功率跟踪控制理论及叶轮与变量泵传动轴力矩平衡方程,建立了变量泵反力矩参考值模型,设计了间接速度控制的压力反馈加转矩控制系统,通过小范围内调节变量泵排量,实现叶轮最大功率捕获。整个系统的性能在自动化工作室(automation studio)中进行了仿真测试,实验样机也进行了海上试验。仿真测试和海试结果显示,该控制系统工作稳定性好,仿真和海试时叶轮的捕获功率系数分别在0.35和0.33附近波动,相比不加控制,分别增加了约0.03和0.05,提高了叶轮的捕获效率,验证了控制系统的有效性。
European Food Safety Authority
2013-07-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance methyl bromide. Although this active substance is no longer authorised within the European Union, guideline levels for methyl bromide (at point of retail sale or when offered for consumption and MRLs for bromide ion, which is a relevant metabolite of methyl bromide, were established by the Codex Alimentarius Commission (CXLs. Regarding methyl bromide, the default MRL of 0.01 mg/kg as defined by Regulation (EC No 396/2005 is compliant with the Codex guideline levels and provides a satisfactory level of protection for the European consumer but it could not be demonstrated that the default MRL can be achieved in routine enforcement. Moreover, based on the assessment of the available data, some CXLs were found not to be adequately supported by data and the consumer risk assessment could not be finalised, as the toxicological reference values of bromide ion need to be revised and only few information on the natural occurrence of bromide ion in food was available to EFSA. Hence, further consideration by risk managers is needed.
Kenmoku, Y.; Sakakibara, T. [Toyohashi University of Technology, Aichi (Japan); Nakagawa, S. [Maizuru College of Technology, Kyoto (Japan); Kawamoto, T. [Shizuoka University, Shizuoka (Japan)
1997-11-25
Storage battery-aided load leveling system is introduced into a power system having a photovoltaic power generation (PV) system, and the effect of the introduction is examined. For this purpose, the resultant improvement on the load factor and reduction in the annual cost are evaluated. Used as the load factor in the studies are the hourly records of power transmitted and received by Chubu Electric Power Co., Inc., in 1995. The output of the PV system is calculated using weather data collected in Nagoya City in the same year. Findings as the result of the studies are stated below. The maximum power is suppressed but a little if it is only the PV system that is introduced into the system. That is, a 2GW PV system introduced into the system suppresses the maximum power only by 0.5GW or less. The maximum power is suppressed more effectively when a storage battery is added, and it decreases linearly with an increase in the storage battery capacity. As for reduction in the cost, the reducing effect is higher when the rate of storage battery capacity/introduced PV capacity is higher in the presence of an introduced PV capacity of 0.8GW or more. 2 refs., 7 figs., 3 tabs.
Transmission Power Level Selection Method Based On Binary Search Algorithm for HiLOW
Lingeswari V Chandra
2011-05-01
Full Text Available Recently the sensor communication research has introduced an IP-based communication known as 6LoWPAN to sensor network. 6LoWPAN was introduced to give a new perspective to sensor network by enabling IPv6 to be applied to wireless sensors as well as wired sensor. Dedicated routing protocols based on 6LoWPAN was soon introduced and Hierarchical Routing Protocol for 6LoWPAN (HiLOW is one of them. HiLOW clearly defines the routing tree setup process, address allocation technique and the data routing process but there is some shortcomings in terms of transmission power selection. HiLOW does not highlight how the suitable transmission power is being selected for sensor communication purpose and this leads to the assumption that at all time and all scenarios the sensors are using maximum transmission power. In the case the sensors are using maximum transmission power for communication even when it is not necessary then power depletion for sensors will be amplified and the network lifetime will be significantly reduced. In this paper we present a brief introduction to 6LoWPAN, a concise review on HiLOW, a highlight on issues revolving each process in HiLOW and propose a new idea on transmission power selection method for HiLOW.
System Level Power Optimization of Digital Audio Back End for Hearing Aids
Pracny, Peter; Jørgensen, Ivan Harald Holger; Bruun, Erik
2017-01-01
This work deals with power optimization of the audio processing back end for hearing aids - the interpolation filter (IF), the sigma-delta (SD modulator and the Class D power amplifier (PA) as a whole. Specifications are derived and insight into the tradeoffs involved is used to optimize...... the interpolation filter and the SD modulator on the system level so that the switching frequency of the Class D PA - the main power consumer in the back end - is minimized. A figure-of-merit (FOM) which allows judging the power consumption of the digital part of the back end early in the design process is used...... to track the hardware and power demands as the tradeoffs of the system level parameters are investigated. The result is the digital part of the back end optimized with respect to power which provides audio performance comparable to state-of-theart. A combination of system level parameters leading...
Design and Analysis of Multi Level D-STATCOM to Improve the Power Quality
Dinesh. Badavath,
2014-01-01
Full Text Available In the last decade, the electrical power quality issue has been the main concern of the power companies. Power quality is defined as the index which both the delivery and consumption of electric power affect on the performance of electrical apparatus. From a customer point of view, a power quality problem can be defined as any problem is manifested on voltage, current, or frequency deviation that results in power failure. The power electronics progressive, especially in flexible alternating-current transmission system (FACTS and custom power devices, affects power quality improvement. This paper presents an investigation of seven-Level Cascaded H - bridge (CHB Inverter as Distribution Static Compensator (DSTATCOM in Power System (PS for compensation of reactive power and harmonics. The advantages of CHB inverter are low harmonic distortion, reduced number of switches and suppression of switching losses. The DSTATCOM helps to improve the power factor and eliminate the Total Harmonics Distortion (THD drawn from a Non-Liner Diode Rectifier Load (NLDRL. The D-Q reference frame theory is used to generate the reference compensating currents for DSTATCOM while Proportional and Integral (PI control is used for capacitor dc voltage regulation. A CHB Inverter is considered for shunt compensation of a 11 Kv distribution system. Finally a level shifted PWM (LSPWM and phase shifted PWM (PSPWM techniques are adopted to investigate the performance of CHB Inverter. The results are obtained through Matlab/Simulink software package.
The Power of Individual-level Drivers of Inventive Performance
Zwick, Thomas; Frosch, Katharina; Hoisl, Karin
2017-01-01
We combine two lines of research on inventive and creative performance that have been separated before. We use empirical models of the performance of inventors over their careers based on an established theoretical framework of the drivers of creativity, the Knowledge, Skills, Abilities, and Other...... (KSAO) model. We link survey information spanning the inventors’ entire careers and psychometric test evidence with patent history data for more than 1000 inventors. We also control for variables that have traditionally been used in studies of inventive performance including inventor age, applicant type......, technology, patent, and time information. We show that educational level, skills acquired during the career, personality traits, career motivation, cognitive ability, and cognitive problem-solving style are significantly related to inventive performance....
Le Brocq, A.; Bentley, M.; Hubbard, A.; Fogwill, C.; Sugden, D.
2008-12-01
A numerical ice sheet model constrained by recent field evidence is employed to reconstruct the Last Glacial Maximum (LGM) ice sheet in the Weddell Sea Embayment (WSE). Previous modelling attempts have predicted an extensive grounding line advance (to the continental shelf break) in the WSE, leading to a large equivalent sea level contribution for the sector. The sector has therefore been considered as a potential source for a period of rapid sea level rise (MWP1a, 20 m rise in ~500 years). Recent field evidence suggests that the elevation change in the Ellsworth mountains at the LGM is lower than previously thought (~400 m). The numerical model applied in this paper suggests that a 400 m thicker ice sheet at the LGM does not support such an extensive grounding line advance. A range of ice sheet surfaces, resulting from different grounding line locations, lead to an equivalent sea level estimate of 1 - 3 m for this sector. It is therefore unlikely that the sector made a significant contribution to sea level rise since the LGM, and in particular to MWP1a. The reduced ice sheet size also has implications for the correction of GRACE data, from which Antarctic mass balance calculations have been derived.
Van de Perre, Evelien; Jacxsens, Liesbeth; Lachat, Carl; El Tahan, Fouad; De Meulenaer, Bruno
2015-01-01
In this study the impact of setting European criteria on exposure to aflatoxin B1 via nuts and figs and ochratoxin A via dried fruits is evaluated for the Belgian population, as an example of the European population. Two different scenarios were evaluated. In scenario 1 all collected literature data are considered, assuming that there is no border control nor legal limits in Europe. In the second scenario, contamination levels above the maximum limits are excluded. The results from scenario 1 demonstrated that if no regulation is in place, AFB1 and OTA concentrations reported in the analysed food can have potential health risk to the population. The estimated exposure of OTA for scenario 2 is below the TDI of 5 ng/kg BW⋅day, indicating that OTA concentrations accepted by EU legislation pose a low risk to the Belgian population. For AFB1, the MOE values of scenario 2 are above 10,000 and can be considered to be of low health concern, based on BDML10 for humans, except for figs (MOE = 5782). This means that for all matrices, with exception of figs, the maximum values of AFB1 in the European legislation are sufficient to be of a low health concern for consumers.
Estimation of probable maximum typhoon wave for coastal nuclear power plant%滨海核电可能最大台风浪的推算
丁赟
2011-01-01
采用当前国际流行的第三代波浪模式SWAN探讨了滨海核电工程可能最大台风浪的计算,并分析了可能最大台风浪与相伴随的可能最大风暴潮成长规律.分析得可能最大台风浪通常滞后可能最大风暴潮增水峰值,推算得到的可能最大台风浪高于遮浪海洋站观测到的最大波高,为滨海核电工程可能最大台风浪的推算提供参考.%The third-generation wave model, SWAN (Simulating Waves Nearshore), was employed to estimate the probable maximum typhoon wave at a coastal engineering area. The relationship between the development of probable maximum typhoon wave and that of probable maximum storm surge was investigated. It is shown that the probable maximum typhoon wave usually occurs later than the probable maximum storm surge. The estimated probable maximum typhoon wave is higher than the historical observational maximum wave height data of Zhelang station. The approach utilized in this study to estimate probable maximum typhoon wave could provide valuable information in design of coastal engineering.
刘军; 王得发; 薛蓉
2016-01-01
The MPPT technology is used a lot in the photovoltaic power generation system,but there are some shortcomings and deficiencies in practical application,such as tracking not fast enough and sometimes oscillation problems.Considering PV system exists to tracking slow and oscillating problems during MPPT,on the analysis of the perturbation and observation method and the hysteresis comparison method we proposes a new MPPT control method which combines the advantages of the two methods and makes the system control technology better. And by comparison with the traditional simulation of disturbance observation method,it verifies that the new method can track the maximum power point quickly,and when the sunshine,temperature changes can effectively reduce the oscillation at the maximum power point of the photovoltaic cell,and verify the correctness and validity of the method.%最大功率跟踪(MPPT)技术是光伏系统中经常使用的跟踪技术，但在使用中存在一定的缺陷和不足之处，如跟踪速度慢和振荡。鉴于这些问题，在此提出了一种结合型的 MPPT 控制方法，该方法在分析了扰动观察法的优势和不足以及概述了滞环比较法原理的基础上，将扰动观察法的跟踪优势与滞环比较法的滞环原理相结合，实现了系统控制方法的优化。并通过与传统的控制方法的仿真图进行对比，通过对比得出该改进方法能快速跟踪到最大功率点及有效减小振荡，验证了该方法的正确性和有效性。
Thorbek, P; Hyder, K
2006-08-01
Residues on foodstuffs resulting from the use of crop-protection products are a function of many factors, e.g. environmental conditions, dissipation and application rate, some of which are linked to the physicochemical properties of the active ingredients. Residue limits (maximum residue levels (MRLs) and tolerances) of fungicides, herbicides and insecticides set by different regulatory authorities are compared, and the relationship between physicochemical properties of the active ingredients and residue limits are explored. This was carried out using simple summary statistics and artificial neural networks. US tolerances tended to be higher than European Union MRLs. Generally, fungicides had the highest residue limits followed by insecticides and herbicides. Physicochemical properties (e.g. aromatic proportion, non-carbon proportion and water solubility) and crop type explained up to 50% of the variation in residue limits. This suggests that physicochemical properties of the active ingredients may control important aspects of the processes leading to residues.
Zvolensky, Michael J; Sachs-Ericsson, Natalie; Feldner, Matthew T; Schmidt, Norman B; Bowman, Carrie J
2006-03-30
The present study evaluated a moderational model of neuroticism on the relation between smoking level and panic disorder using data from the National Comorbidity Survey. Participants (n=924) included current regular smokers, as defined by a report of smoking regularly during the past month. Findings indicated that a generalized tendency to experience negative affect (neuroticism) moderated the effects of maximum smoking frequency (i.e., number of cigarettes smoked per day during the period when smoking the most) on lifetime history of panic disorder even after controlling for drug dependence, alcohol dependence, major depression, dysthymia, and gender. These effects were specific to panic disorder, as no such moderational effects were apparent for other anxiety disorders. Results are discussed in relation to refining recent panic-smoking conceptual models and elucidating different pathways to panic-related problems.
Adam-Poupart, Ariane; Brand, Allan; Fournier, Michel; Jerrett, Michael
2014-01-01
Background: Ambient air ozone (O3) is a pulmonary irritant that has been associated with respiratory health effects including increased lung inflammation and permeability, airway hyperreactivity, respiratory symptoms, and decreased lung function. Estimation of O3 exposure is a complex task because the pollutant exhibits complex spatiotemporal patterns. To refine the quality of exposure estimation, various spatiotemporal methods have been developed worldwide. Objectives: We sought to compare the accuracy of three spatiotemporal models to predict summer ground-level O3 in Quebec, Canada. Methods: We developed a land-use mixed-effects regression (LUR) model based on readily available data (air quality and meteorological monitoring data, road networks information, latitude), a Bayesian maximum entropy (BME) model incorporating both O3 monitoring station data and the land-use mixed model outputs (BME-LUR), and a kriging method model based only on available O3 monitoring station data (BME kriging). We performed leave-one-station-out cross-validation and visually assessed the predictive capability of each model by examining the mean temporal and spatial distributions of the average estimated errors. Results: The BME-LUR was the best predictive model (R2 = 0.653) with the lowest root mean-square error (RMSE ;7.06 ppb), followed by the LUR model (R2 = 0.466, RMSE = 8.747) and the BME kriging model (R2 = 0.414, RMSE = 9.164). Conclusions: Our findings suggest that errors of estimation in the interpolation of O3 concentrations with BME can be greatly reduced by incorporating outputs from a LUR model developed with readily available data. Citation: Adam-Poupart A, Brand A, Fournier M, Jerrett M, Smargiassi A. 2014. Spatiotemporal modeling of ozone levels in Quebec (Canada): a comparison of kriging, land-use regression (LUR), and combined Bayesian maximum entropy–LUR approaches. Environ Health Perspect 122:970–976; http://dx.doi.org/10.1289/ehp.1306566 PMID:24879650
Lionello, Piero; Conte, Dario; Marzo, Luigi; Scarascia, Luca
2017-04-01
The maximum level that water reaches during a storm along the coast has important consequences on coastal defences and coastal erosion. It depends on future sea level, storm surges, ocean wind generated waves, vertical land motion. The future sea level in turn depends on water mass addition and steric contributions (with a thermosteric and halosteric component). This study proposes a practical methodology for assessing the effects of these different factors (which need to be estimated at sub-regional scale) and applies it to a 7-member model ensemble of regional climate model simulations (developed and carried out in the CIRCE fp6 project) covering the period 1951-2050 under the A1B emission scenario. Sea level pressure and wind fields are used for forcing a hydro-dynamical shallow water model (HYPSE), wind fields are used for forcing a wave model (WAM), obtaining estimates of storm surges and ocean waves, respectively. Thermosteric and halosteric effects are diagnosed from the projections of sea temperature and salinity. Steric expansion and storminess are shown to be contrasting factors: in the next decades wave and storm surge maxima will decrease while thermosteric expansion will increase mean sea level. These two effects will to a large extent compensate each other, so that their superposition will increase/decrease the maximum water level along two comparable fractions of the coastline (about 15-20%) by the mid 21st century. However, mass addition across the Gibraltar Strait to the Mediterranean Sea will likely become the dominant factor and determine an increase of the maximum water level along most of the coastline.
Funabiki, Shigeyuki; Tanaka, Toshihiko; Fujii, Toshinori
A new optimization method of the electric power leveling system using an SMES is proposed. The SMES is parallelly connected with rolling mills in steel works. The leveling control is based on fuzzy reasoning. The SMES capacity and the scaling factors of the fuzzy controller will be optimized so that the power leveling control can be achieved and then the total cost of the added SMES cost and reduced contract electricity rate becomes lower. The optimization is carried out using the genetic algorithm and the cost reduction of 7.76 billion yen can be achieved. It is confirmed by the power leveling simulation that the proposed optimization method is very effective for designing the power leveling system.
Levels of Involvement: The Power of Choice in a Middle School Level System
Havill, Laura K.
2004-01-01
This article outlines the development of a level system for a self-contained middle school program serving students with emotional and behavioral disorders. This level system is a real alternative to traditional control and coercion models. The Turning Point Middle School's level system incorporates aspects of the Circle of Courage, Choice Theory,…
The Level of Power Quality Measurement and Evaluation in A Stone Crusher Plant
Mustafa ŞEKKELİ
2009-03-01
Full Text Available Both electric utilities and end users of electric power are becoming increasingly concerned about the quality of electric power. Quality of electrical energy in the electrical system that is requested continuous power (uninterrupted power, constant frequency and with constant amplitude can be explained by sinusoidal voltage. Deformation of voltage in the form of sinusoidal waveform is explained as a harmonic. Harmonics are most important factors in decreasing quality of energy in the electrical system. In industrial plants, existence of harmocins and voltage drop, causes serious problems both in plant and network. This problem affects the cost. In this study, a power quality measurements are carried out in stone crusher plant. Harmonics and voltage drop has been measured and evaluated with the power analyzer. In the power quality measurements, harmonic level of the plant is not so bad. However, it is recommended that compensation system with harmonic elimination can be established in plant.
Optimization of Electric Power Leveling Systems by a Novel Cluster-Structured GA with Masking
Itoh, Jyunpei; Fujii, Toshinori; Funabiki, Shigeyuki
Power fluctuations of the rolling mill may cause the instability of electric power systems, and increase the cost of the electric power facility and electricity charges. Therefore, in order to compensate the power fluctuations, the development of the electric power-leveling systems (EPLS) is very important in the future electric power system. The EPLS with a SMES has been proposed as one of the countermeasures for the electric power quality improvement. However, the SMES is very expensive and it is difficult to decide the gains of the controller. It is essential in the practical use that the reduction of SMES capacity is realized. This paper proposes a new optimization method of the EPLS. The proposed algorithm is Cluster-Structured GA with Masking (CSGA). The optimization of the EPLS can be achieved by the proposed CSGA compared to the GA.
A Fast Approach for System-Level Power Modeling and Simulation
XIAJun; ZOUXuecheng
2004-01-01
Power is one of the main constraints in SOC (System-on-a-chip) design. System-level power modeling and simulation help to reduce the power dissipation in early stage. But by reason of the variability of system architecture, the amount of simulation is vast which result in the simulation time is unacceptable. On the basis of previous work, a modified hybrid approach for core-based system-level power modeling is proposed in this paper, which enables SOC designers to estimate system power consumption under different core parameters and just simulates the system only once. Thereafter designers can make a trade-off rapidly between performance characters (such as power, area, speed and test, etc) and make a decision about which architecture is the best solution to implement system functionality. The key of our approach is to help the core designers to provide a power metric function to the core users and the effectiveness and efficiency of our approach hinge on whether the IP provider could provide an accurate power model of each core. A linear model is chosen to describe the relationship between power consumption and parameters and least-square-error is selected as the optimization criterion to mitigate error. Although the power is given as an example, our approach can be applied to speed and area performance trade-off also because speed and area performance modeling is simpler relatively.
Building America Case Study: Photovoltaic Systems with Module-Level Power Electronics
2015-09-01
Direct current (DC) power optimizers and microinverters (together known as module-level power electronics, or MLPE) are one of the fastest growing market segments in the solar industry. According to GTM Research in The Global PV Inverter Landscape 2015, over 55% of all residential photovoltaic (PV) installations in the United States used some form of MLPE in 2014.
Blom, S.; Bellettini, C.; Sinigalliesi, A.; Stabellini, L.; Rossi, M.; Mazzini, G.
2005-01-01
In this work we focus on the new generation EYESIFXv2 [1] wireless sensor nodes by carrying out experimental measurements on power related quantities. In particular, our aim is to characterize the relationship between the level of the battery and the transmission power radiated by the node. The pres
EFSA Panel on Contaminants in the Food Chain (CONTAM
2013-12-01
Full Text Available The European Food Safety Authority (EFSA was asked to deliver a scientific opinion on the risks for public health related to a possible increase of the maximum level (ML of deoxynivalenol (DON for certain semi-processed cereal products from 750 µg/kg to 1000 µg/kg. For this statement, EFSA relied on existing occurrence data on DON in food collected between 2007 and 2012 and reported by 21 European countries. Due to the lack of appropriate occurrence data from pre-market monitoring, the impact of increasing the ML was estimated using a simulation approach, resulting in an expected increase in mean levels of the respective food products by a factor of 1.14-1.16. Based on median chronic exposure in several age classes, the percentage of consumers exceeding the group provisional maximum tolerable daily intake (PMTDI of 1 μg/kg body weight (b.w. for the sum of DON and its 3- and 15-acetyl-derivatives, established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA in 2010, is approximately 2-fold higher with the suggested increased ML than with the current ML. Several acute exposure scenarios resulted in exceedance of the group acute reference dose (ARfD of 8 µg/kg b.w. established by JECFA with up to 25.9 % of the consumption days above the group ARfD. The EFSA Scientific Panel on Contaminants in the Food Chain notes that the group health based guidance values (HBGVs include 3-Ac-DON and 15-Ac-DON. The exposure from the acetyl-derivatives has not been covered in this statement, since the acetyl-derivatives are not included in the current or suggested increased ML and because only few occurrence data are available. An increase of the DON ML can be expected to be associated with an increase of the levels of DON and Ac-DONs, and can therefore increase the exposure and consequently the exceedances of the group HBGVs.
Singh, Mukhtiyar [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India); Saini, Hardev S. [Department of Physics, Panjab University, Chandigarh-160014 (India); Thakur, Jyoti [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India); Reshak, Ali H. [New Technologies—Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Kashyap, Manish K., E-mail: manishdft@gmail.com [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India)
2014-12-15
We report full potential treatment of electronic and magnetic properties of Cr{sub 2−x}Fe{sub x}CoZ (Z=Al, Si) Heusler alloys where x=0.0, 0.25, 0.5, 0.75 and 1.0, based on density functional theory (DFT). Both parent alloys (Cr{sub 2}CoAl and Cr{sub 2}CoSi) are not half-metallic frromagnets. The gradual replacement of one Cr sublattice with Fe induces the half-metallicity in these systems, resulting maximum spin polarization. The half-metallicity starts to appear in Cr{sub 2−x}Fe{sub x}CoAl and Cr{sub 2−x}Fe{sub x}CoSi with x=0.50 and x=0.25, respectively, and the values of minority-spin gap and half-metallic gap or spin-flip gap increase with further increase of x. These gaps are found to be maximum for x=1.0 for both cases. An excellent agreement between the structural properties of CoFeCrAl with available experimental study is obtained. The Fermi level tuning by Fe-doping makes these alloys highly spin polarized and thus these can be used as promising candidates for spin valves and magnetic tunnelling junction applications. - Highlights: • Tuning of E{sub F} in Cr{sub 2}CoZ (Z=Al, Si) has been demonstrated via Fe doping. • Effect of Fe doping on half-metallicity and magnetism have been discussed. • The new alloys have a potential of being used as spin polarized electrodes.
European Food Safety Authority
2015-01-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance glufosinate. In order to assess the occurrence of glufosinateresidues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing and a possible acute risk to consumers was identified. Hence, the consumer risk assessment is considered indicative only, some MRL proposals derived by EFSA still require further consideration by risk managers and measures for reduction of the consumer exposure should also be considered.
European Food Safety Authority
2014-03-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance thiacloprid. In order to assess the occurrence of thiacloprid residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing and a possible acute risk to consumers was identified. Hence, the consumer risk assessment is considered indicative only, some MRL proposals derived by EFSA still require further consideration by risk managers and measures for reduction of the consumer exposure should also be considered.
European Food Safety Authority
2015-01-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance pirimiphos-methyl. In order to assess the occurrence of pirimiphos-methyl residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing and a possible chronic risk to consumers was identified. Hence, the consumer risk assessment is considered indicative only, all MRL proposals derived by EFSA still require further consideration by risk managers and measures for reduction of the consumer exposure should also be considered.
European Food Safety Authority
2013-04-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance flusilazole. In order to assess the occurrence of flusilazole residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing and a possible acute risk to consumers was identified. Hence, the consumer risk assessment is considered indicative only, some MRL proposals derived by EFSA still require further consideration by risk managers and measures for reduction of the consumer exposure should also be considered.
European Food Safety Authority
2014-01-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance methoxyfenozide. In order to assess the occurrence of methoxyfenozide residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified regarding the European authorisations, some information required by the regulatory framework was found to be missing and a possible acute risk to consumers was identified for some of the MRLs established by the Codex Alimentarius Commission. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers.
European Food Safety Authority
2013-04-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance propamocarb. In order to assess the occurrence of propamocarb residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing and a possible acute risk to consumers was identified. Hence, the consumer risk assessment is considered indicative only, some MRL proposals derived by EFSA still require further consideration by risk managers and measures for reduction of the consumer exposure should also be considered.
European Food Safety Authority
2014-04-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance captan. In order to assess the occurrence of captan residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing and a possible acute risk to consumers was identified. Hence, the consumer risk assessment is considered indicative only, some MRL proposals derived by EFSA still require further consideration by risk managers and measures for reduction of the consumer exposure should also be considered.
European Food Safety Authority
2012-10-01
Full Text Available
According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance chlorothalonil. In order to assess the occurrence of chlorothalonil residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals for parent chlorothalonil in plant commodities and for 2,5,6-trichloro-4-hydroxyphtalonitrile (SDS-3701 in animal commodities were derived, and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing (in particular with regard to metabolite SDS-3701 and a possible acute risk to consumers was identified for parent chlorothalonil. Hence, the consumer risk assessment is considered indicative only, all MRL proposals derived by EFSA still require further consideration by risk managers and measures for reduction of the consumer exposure should also be considered.
European Food Safety Authority
2014-01-01
Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance lambda-cyhalothrin. In order to assess the occurrence of lambda-cyhalothrin residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the import tolerances and European authorisations reported by Member States (incl. the supporting residues data. Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing and a possible acute risk to consumers was identified. Hence, the consumer risk assessment is considered indicative only, some MRL proposals derived by EFSA still require further consideration by risk managers and measures for reduction of the consumer exposure should also be considered.
Bidirectional Five-Level Power Processing Interface for Low Voltage Battery Energy Storage System
Huang, Jain-Yi; Jou, Hurng-Liahng; Wu, Kuen-Der; Lin, You-Si; Wu, Jinn-Chang
A bidirectional five-level power processing interface for low voltage battery energy storage system (BESS) is developed in this paper. This BESS consists of a bidirectional five-level DC-AC converter, a bidirectional dual boost/buck DC-DC converter and a battery set. This five-level DC-AC converter includes a bidirectional full-bridge converter and a bidirectional dual buck DC-DC converter. The five-level power processing interface can charge power to the battery set form the utility or discharge the power from the battery set to the utility depending on the demanded operation of user. A hardware prototype is developed to verify the performance of this BESS. Experimental results show the performance of the developed BESS is as expected.
Integrating High Levels of Variable Renewable Energy into Electric Power Systems
Kroposki, Benjamin D. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2017-08-01
As more variable renewable energy is integrated into electric power systems, there are a range of challenges and solutions to accommodating very high penetration levels. This presentation highlights some of the recent research in this area.
Low-Carbon Based Multi-Objective Bi-Level Power Dispatching under Uncertainty
Xiaoyang Zhou
2016-06-01
Full Text Available This research examines a low-carbon power dispatch problem under uncertainty. A hybrid uncertain multi-objective bi-level model with one leader and multiple followers is established to support the decision making of power dispatch and generation. The upper level decision maker is the regional power grid corporation which allocates power quotas to each follower based on the objectives of reasonable returns, a small power surplus and low carbon emissions. The lower level decision makers are the power generation groups which decide on their respective power generation plans and prices to ensure the highest total revenue under consideration of government subsidies, environmental costs and the carbon trading. Random and fuzzy variables are adopted to describe the uncertain factors and chance constrained and expected value programming are used to handle the hybrid uncertain model. The bi-level models are then transformed into solvable single level models using a satisfaction method. Finally, a detailed case study and comparative analyses are presented to test the proposed models and approaches to validate the effectiveness and illustrate the advantages.
Andrea Bonfiglio
2017-01-01
Full Text Available This paper focuses on the modeling of wind turbines equipped with direct drive permanent magnet synchronous generators for fundamental frequency power system simulations. Specifically, a procedure accounting for the system active power losses to initialize the simulation starting from the load flow results is proposed. Moreover, some analytical assessments are detailed on typical control schemes for fully rated wind turbine generators, thereby highlighting how active power losses play a fundamental role in the effectiveness of the wind generator control algorithm. Finally, the paper proposes analytical criteria to design the structure and the parameters of the regulators of the wind generator control scheme. Simulations performed with Digsilent Power Factory validated the proposed procedure, highlighting the impact of active power losses on the characterization of the initial steady state and that the simplifying assumptions done in order to synthesize the controllers are consistent with the complete modeling performed by the aforementioned power system simulator.
葛超铭; 李少纲
2013-01-01
为了实现风光互补发电系统的最大功率点跟踪(MPPT)，根据风能与太阳能的特性，采用双输入DC/DC变换器作为前级电路，在扰动法的基础上提出自调整MPPT控制策略，有效改善了系统的跟踪速度，避免误操作，减小工作点的震荡，并提高了系统效率。针对逆变电源控制，把自动调节反馈系数的PID控制系统与重复控制系统相结合，不仅提出复合控制算法，使系统具有较好的动静态特性，且改善了逆变器输出波形的质量。%In order to realize maximum power point tracking (MPPT) of hybrid photovoltaic-wind power generation system, dual input DC/DC converter was adopted as the forward circuit according to features of wind energy and solar energy. On the basis of disturbance method, the self-adjusting MPPT control strategy was raised to have effectively improved tracking speed of the system, avoiding misopera-tion, reducing vibration of working point and raising the system efficiency. As for inverter control, the PID control system for auto-adjusting feeding coefficient was combined with the repetitive control system. This paper not only raised the repetitive control algorithm, making the system have better static and dynamic characteristics, but also improved quality of inverter output waveforms.
Lonn, S; Forssen, U; P. Vecchia; Ahlbom, A; Feychting, M
2004-01-01
Background: The power level used by the mobile phone is one of the most important factors determining the intensity of the radiofrequency exposure during a call. Mobile phone calls made in areas where base stations are densely situated (normally urban areas) should theoretically on average use lower output power levels than mobile phone calls made in areas with larger distances between base stations (rural areas).
Thermal analysis of multi-MW two-level wind power converter
Zhou, Dao; Blaabjerg, Frede; Mogens, Lau; Tonnes, Michael
2012-01-01
In this paper, the multi-MW wind turbine of partial-scale and full-scale two-level power converter with DFIG and direct-drive PMSG are designed and compared in terms of their thermal performance. Simulations of different configurations regarding loss distribution and junction temperature in the power device in the whole range of wind speed are presented and analyzed. It is concluded that in both partial-scale and full-scale power converter the most thermal stressed power device in the generat...
Igarashi, M. [Meidensha Corp., Tokyo (Japan)
1996-06-28
An overview is given on the development situation of a Zn-Br battery as a power storage system. The system is aimed at storing excess power at night and supplying the on-load demand during daytime. The power storage technology requires a large output and capacity of MWh level, long term stability and durability, and cost as low as pumped storage power generation. Four kinds of batteries have been examined to cope with the conditions, in which development of Zn-Br batteries along with Na-S batteries is in progress towards practicability. As a power conversion method for this system, GTO has been employed for a large capacity unit and IGBT for a medium/small capacity unit. The reliability of the Zn-Br batteries against leakage was improved by laminating each cell by hot plate welding. The service life was improved by using a material with a high bromine resistance in place of the conventional electrode constituent material. Although the battery efficiency was influenced by each resistance of electrode, film and electrolytic solution, distance between electrodes, temperature, etc., these correlations were clarified so as to establish the simulation technology. At present, the system realizes 50kW and 40kWh/m{sup 3}. 1 ref., 8 figs.
Power estimation for intellectual property-based digital systems at the architectural level
Yaseer Arafat Durrani
2014-09-01
We present an efficient power macro-modeling technique at the architectural level for digital electronic systems. This technique estimates the power dissipation of intellectual property (IP components to their statistical knowledge of the primary inputs/outputs. During the power estimation method, the sequence of an input stream is generated by a genetic algorithm (GA using input metrics and the macro-model function to construct a set of functions that map the input metrics of a macro-block to its output metrics. Then, a Monte Carlo zero-delay simulation is performed and the power dissipation is predicted by a macro-model function. The most important contribution of the technique is that it allows fast power estimation of IP-based design by the simple addition of individual power consumption. This makes the power modeling of SoCs an easy task that permits evaluation of power features at the architectural level. In order to evaluate our model, we have constructed IP-based digital systems using different IP macro-blocks. In experiments with an individual IP macro-block the average error is 1–2% and for an entire IP-based system with interconnects, the error range is from 9% to 15%. The preliminary results are effective and our macro-model provides accurate power estimation.
Eduardo Backhoff Escudero
2000-05-01
Full Text Available The Basic Knowledge and Skills Examination (EXHCOBA is one of the few great-scale examinations in Mexico which has been publishing its psychometric parameters. In this paper we describe the item analysis results, regarding the exam’s difficulty level and discrimination power. Results show that most of the items have a medium difficulty and a high discrimination power. They also reveal that the mathematics items have better discrimination power levels than the ones which belong to social science.
Modular Multi-level converter based HVDC System for Grid Connection of Offshore Wind Power Plant
Gnanarathna, U.N.; Chaudhary, Sanjay Kumar; Gole, A.M.;
2010-01-01
This paper explores the application of modular multi-level converters (MMC) as a means for harnessing the power from off-shore wind power plants. The MMC consists of a large number of simple voltage sourced converter (VSC) submodules that can be easily assembled into a converter for high......-voltage and high power. The paper shows that the MMC converter has a fast response and low harmonic content in comparison with a two-level VSC option. The paper discusses the modeling approach used, including a solution to the modeling challenge imposed by the very large number of switching devices in the MMC....
Białous, Małgorzata; Yunko, Vitalii; Bauch, Szymon; Ławniczak, Michał; Dietz, Barbara; Sirko, Leszek
2016-09-01
We present experimental studies of the power spectrum and other fluctuation properties in the spectra of microwave networks simulating chaotic quantum graphs with violated time reversal invariance. On the basis of our data sets, we demonstrate that the power spectrum in combination with other long-range and also short-range spectral fluctuations provides a powerful tool for the identification of the symmetries and the determination of the fraction of missing levels. Such a procedure is indispensable for the evaluation of the fluctuation properties in the spectra of real physical systems like, e.g., nuclei or molecules, where one has to deal with the problem of missing levels.
Zhou, Dao; Wang, Huai; Blaabjerg, Frede
2016-01-01
DC capacitors in power electronic converters are a major constraint on improvement of the power density and the reliability. In this paper, according to the degradation data of tested capacitors, the lifetime model of the component is analyzed at various confidence levels. Then, the mission profile...... based lifetime expectancy of the individual capacitor and the capacitor bank is estimated in a fuel cell backup power converter operating in both standby mode and operation mode. The lifetime prediction of the capacitor banks at different confidence levels is also obtained....
Zhou, Dao; Wang, Huai; Blaabjerg, Frede
2016-01-01
DC capacitors in power electronic converters are a major constraint on improvement of the power density and the reliability. In this paper, according to the degradation data of tested capacitors, the lifetime model of the component is analyzed at various confidence levels. Then, the mission profile...... based lifetime expectancy of the individual capacitor and the capacitor bank is estimated in a fuel cell backup power converter operating in both standby mode and operation mode. The lifetime prediction of the capacitor banks at different confidence levels is also obtained....
System-level Reliability Assessment of Power Stage in Fuel Cell Application
Zhou, Dao; Wang, Huai; Blaabjerg, Frede
2016-01-01
High efficient and less pollutant fuel cell stacks are emerging and strong candidates of the power solution used for mobile base stations. In the application of the backup power, the availability and reliability hold the highest priority. This paper considers the reliability metrics from...... the component-level to the system-level for the power stage used in a fuel cell application. It starts with an estimation of the annual accumulated damage for the key power electronic components according to the real mission profile of the fuel cell system. Then, considering the parameter variations in both...... reliability. In a case study of a 5 kW fuel cell power stage, the parameter variations of the lifetime model prove that the exponential factor of the junction temperature fluctuation is the most sensitive parameter. Besides, if a 5-out-of-6 redundancy is used, it is concluded both the B10 and the B1 system...
Power level effects on thorium-based fuels in pressure-tube heavy water reactors
Bromley, B.P.; Edwards, G.W.R., E-mail: blair.bromley@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Sambavalingam, P. [Univ. of Ontario Inst. of Technology, Oshawa, Ontario (Canada)
2016-06-15
Lattice and core physics modeling and calculations have been performed to quantify the impact of power/flux levels on the reactivity and achievable burnup for 35-element fuel bundles made with Pu/Th or U-233/Th. The fissile content in these bundles has been adjusted to produce on the order of 20 MWd/kg burnup in homogeneous cores in a 700 MWe-class pressure-tube heavy water reactor, operating on a once-through thorium cycle. Results demonstrate that the impact of the power/flux level is modest for Pu/Th fuels but significant for U-233/Th fuels. In particular, high power/flux reduces the breeding and burnup potential of U-233/Th fuels. Thus, there may be an incentive to operate reactors with U-233/Th fuels at a lower power density or to develop alternative refueling schemes that will lower the time-average specific power, thereby increasing burnup.(author)
Jovanovic, S.M. (Nikola Tesla Inst., Belgrade (YU))
1990-01-01
This paper presents a model and an appropriate numerical procedure for a four-level time decomposition quasi-static power flow and successive disturbances analysis of power systems. The analysis consists of the sequential computation of the zero, primary, secondary and tertiary quasi-static states and of the estimation of successive structural disturbances during the 1200 s dynamics after a structural disturbance. The model is developed by detailed inspection of the time decomposition characteristics of automatic protection and control devices. Adequate speed of the numerical procedure is attained by a specific application of the inversion matrix lemma and the decoupled model constant coefficient matrices. The four-level time decomposition quasi-static method is intended for security and emergency analysis. (author).
Scalability of components for kW-level average power few-cycle lasers.
Hädrich, Steffen; Rothhardt, Jan; Demmler, Stefan; Tschernajew, Maxim; Hoffmann, Armin; Krebs, Manuel; Liem, Andreas; de Vries, Oliver; Plötner, Marco; Fabian, Simone; Schreiber, Thomas; Limpert, Jens; Tünnermann, Andreas
2016-03-01
In this paper, the average power scalability of components that can be used for intense few-cycle lasers based on nonlinear compression of modern femtosecond solid-state lasers is investigated. The key components of such a setup, namely, the gas-filled waveguides, laser windows, chirped mirrors for pulse compression and low dispersion mirrors for beam collimation, focusing, and beam steering are tested under high-average-power operation using a kilowatt cw laser. We demonstrate the long-term stable transmission of kW-level average power through a hollow capillary and a Kagome-type photonic crystal fiber. In addition, we show that sapphire substrates significantly improve the average power capability of metal-coated mirrors. Ultimately, ultrabroadband dielectric mirrors show negligible heating up to 1 kW of average power. In summary, a technology for scaling of few-cycle lasers up to 1 kW of average power and beyond is presented.
Ciobotaru, Mihai; Iov, Florin; Zanchetta, Pericle
2008-01-01
More "green" power provided by Distributed Generation will enter into the European electricity network in the near future. In order to control the power flow and to ensure proper and secure operation of this future grid, with an increased level of the renewable power, new power electronic convert...
Maximum information photoelectron metrology
Hockett, P; Wollenhaupt, M; Baumert, T
2015-01-01
Photoelectron interferograms, manifested in photoelectron angular distributions (PADs), are a high-information, coherent observable. In order to obtain the maximum information from angle-resolved photoionization experiments it is desirable to record the full, 3D, photoelectron momentum distribution. Here we apply tomographic reconstruction techniques to obtain such 3D distributions from multiphoton ionization of potassium atoms, and fully analyse the energy and angular content of the 3D data. The PADs obtained as a function of energy indicate good agreement with previous 2D data and detailed analysis [Hockett et. al., Phys. Rev. Lett. 112, 223001 (2014)] over the main spectral features, but also indicate unexpected symmetry-breaking in certain regions of momentum space, thus revealing additional continuum interferences which cannot otherwise be observed. These observations reflect the presence of additional ionization pathways and, most generally, illustrate the power of maximum information measurements of th...
Garrido, Nuno D; Silva, António J; Fernandes, Ricardo J; Barbosa, Tiago M; Costa, Aldo M; Marinho, Daniel A; Marques, Mário C
2012-06-01
The relationship between handgrip isometric strength and swimming performance was assessed in the four competitive swimming strokes in swimmers of different age groups and of both sexes. 78 national-level Portuguese swimmers (39 males, 39 females) were selected for this study. Grip strength, previously used as a marker of overall strength to predict future swimming performance, was measured using a hand dynamometer. The best competitive time at 100 and 200 m in all four swimming strokes were converted into 2010 FINA points. Non-parametric tests were used to evaluate differences between groups. Pearson product-moment correlations were computed to verify the association between variables. Handgrip maximum isometric strength was significantly correlated with swimming performance, particularly among female swimmers. Among female age group swimmers, the relationship between handgrip and 100-m freestyle was significant. Handgrip isometric strength seems to be related to swimming performance, especially to 100-m freestyle and in female swimmers. For all other distances and strokes, technique and training probably are more influential than semi-hereditary strength markers such as grip strength.
Doganlar, Oguzhan; Doganlar, Zeynep Banu; Tabakcioglu, Kiymet
2015-10-01
In this study, we aimed to investigate the mutagenic and carcinogenic potential of a volatile organic compound (VOC) mixture with references to the response of D.melanogaster using selected antioxidant gene expressions, RAPD assay and base-pair change of ribosomal 18S, and the internal transcribed spacer, ITS2 rDNA gene sequences. For this purpose, Drosophila melanogaster Oregon R, reared under controlled conditions on artificial diets, were treated with the mixture of thirteen VOCs, which are commonly found in water in concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. In the random amplified polymorphic DNA (RAPD) assay, band changes were clearly detected, especially at the 50 and 75 ppb exposure levels, for both treatment periods, and the band profiles exhibited clear differences between the treated and untreated flies with changes in band intensity and the loss/appearance of bands. Quantitative real-time PCR (qRT-PCR) analysis of Mn-superoxide dismutase (Mn-SOD), catalase (CAT) and glutathione-synthetase (GS) expressions demonstrated that these markers responded significantly to VOC-induced oxidative stress. Whilst CAT gene expressions increased linearly with increasing concentrations of VOCs and treatment times, the 50- and 75-ppb treatments caused decreases in GS expressions compared to the control at 5 days. Treatment with VOCs at both exposure times, especially in high doses, caused gene mutation of the 18S and the ITS2 ribosomal DNA. According to this research, we thought that the permissible maximum-contamination level of VOCs can cause genotoxic effect especially when mixed.
Wafer-level chip-scale packaging analog and power semiconductor applications
Qu, Shichun
2015-01-01
This book presents a state-of-art and in-depth overview in analog and power WLCSP design, material characterization, reliability, and modeling. Recent advances in analog and power electronic WLCSP packaging are presented based on the development of analog technology and power device integration. The book covers in detail how advances in semiconductor content, analog and power advanced WLCSP design, assembly, materials, and reliability have co-enabled significant advances in fan-in and fan-out with redistributed layer (RDL) of analog and power device capability during recent years. Along with new analog and power WLCSP development, the role of modeling is a key to assure successful package design. An overview of the analog and power WLCSP modeling and typical thermal, electrical, and stress modeling methodologies is also provided. This book also: · Covers the development of wafer-level power discrete packaging with regular wafer-level design concepts and directly bumping technology · �...