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Sample records for two-method mppt control

  1. A Combined Two-Method MPPT Control Scheme for Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Dorofte, Christinel; Borup, Uffe; Blaabjerg, Frede

    2005-01-01

    In order to increase the output efficiency of a grid-connected photovoltaic (PV) system it is important to have an efficient Maximum Power Point Tracker (MPPT). In the case of low irradiation, the Perturb and Observe (PO) and Incremental Conductance (IC) methods have a poor efficiency, because...... of the poor resolution in the acquired signals, when a fixed point implementation is done. A cost-effective two-method MPPT control scheme is proposed in this paper to track the maximum power point (MPP) at both low and high irradiation, by combining a Constant Voltage (CV) method and modified PO algorithm...

  2. A Combined Two-Method MPPT Control Scheme for Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Dorofte, Christinel; Borup, Uffe; Blaabjerg, Frede

    2005-01-01

    of the poor resolution in the acquired signals, when a fixed point implementation is done. A cost-effective two-method MPPT control scheme is proposed in this paper to track the maximum power point (MPP) at both low and high irradiation, by combining a Constant Voltage (CV) method and modified PO algorithm......In order to increase the output efficiency of a grid-connected photovoltaic (PV) system it is important to have an efficient Maximum Power Point Tracker (MPPT). In the case of low irradiation, the Perturb and Observe (PO) and Incremental Conductance (IC) methods have a poor efficiency, because...

  3. MPPT algorithm for voltage controlled PV inverters

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Teodorescu, Remus; Liserre, Marco

    2008-01-01

    This paper presents a novel concept for an MPPT that can be used in case of a voltage controlled grid connected PV inverters. In case of single-phase systems, the 100 Hz ripple in the AC power is also present on the DC side. Depending on the DC link capacitor, this power fluctuation can be used...

  4. Photovoltaic Cells Mppt Algorithm and Design of Controller Monitoring System

    Science.gov (United States)

    Meng, X. Z.; Feng, H. B.

    2017-10-01

    This paper combined the advantages of each maximum power point tracking (MPPT) algorithm, put forward a kind of algorithm with higher speed and higher precision, based on this algorithm designed a maximum power point tracking controller with ARM. The controller, communication technology and PC software formed a control system. Results of the simulation and experiment showed that the process of maximum power tracking was effective, and the system was stable.

  5. Design of MPPT Controller Monitoring Software Based on QT Framework

    Science.gov (United States)

    Meng, X. Z.; Lu, P. G.

    2017-10-01

    The MPPT controller was a hardware device for tracking the maximum power point of solar photovoltaic array. Multiple controllers could be working as networking mode by specific communicating protocol. In this article, based on C++ GUI programming with Qt frame, we designed one sort of desktop application for monitoring and analyzing operational parameter of MPPT controller. The type of communicating protocol for building network was Modbus protocol which using Remote Terminal Unit mode and The desktop application of host computer was connected with all the controllers in the network through RS485 communication or ZigBee wireless communication. Using this application, user could monitor the parameter of controller wherever they were by internet.

  6. Analysis of MPPT Failure and Development of an Augmented Nonlinear Controller for MPPT of Photovoltaic Systems under Partial Shading Conditions

    Directory of Open Access Journals (Sweden)

    Mingxuan Chen

    2017-01-01

    Full Text Available The output–voltage–power curves of photovoltaic (PV arrays exhibit complex multi-peak shapes when local shading occurs. The existing maximum power point tracking (MPPT algorithms to solve this multi-peak problem do not consider the possibility of tracking failures due to the time of the irradiance change. In this study, first, the reason for the failure of the global MPPT (GMPPT algorithm is analyzed based on the PV array mathematical model and its output characteristics under partial shading conditions; then, in order to estimate the MPP voltage, an artificial neural network (ANN is trained using environmental information such as irradiance. A hybrid MPPT method using an augmented state feedback precise linearization (AFL controller combined with an ANN is proposed to solve problems such as the shift of the static operating point of the DC/DC boost converter. Finally, numerical simulations are conducted to validate the proposed method and eliminate the possibility of MPPT failure. The proposed hybrid MPPT method is compared with the conventional perturb and observe (P & O method and the improved P & O method through simulations. Using the proposed neural network and nonlinear control strategy, the MPP can be tracked rapidly, accurately, and statically, proving that the method is feasible and effective.

  7. Fuzzy Logic Based MPPT Controller for a PV System

    Directory of Open Access Journals (Sweden)

    Carlos Robles Algarín

    2017-12-01

    Full Text Available The output power of a photovoltaic (PV module depends on the solar irradiance and the operating temperature; therefore, it is necessary to implement maximum power point tracking controllers (MPPT to obtain the maximum power of a PV system regardless of variations in climatic conditions. The traditional solution for MPPT controllers is the perturbation and observation (P&O algorithm, which presents oscillation problems around the operating point; the reason why improving the results obtained with this algorithm has become an important goal to reach for researchers. This paper presents the design and modeling of a fuzzy controller for tracking the maximum power point of a PV System. Matlab/Simulink (MathWorks, Natick, MA, USA was used for the modeling of the components of a 65 W PV system: PV module, buck converter and fuzzy controller; highlighting as main novelty the use of a mathematical model for the PV module, which, unlike diode based models, only needs to calculate the curve fitting parameter. A P&O controller to compare the results obtained with the fuzzy control was designed. The simulation results demonstrated the superiority of the fuzzy controller in terms of settling time, power loss and oscillations at the operating point.

  8. Distributed control of PV strings with module integrated converters in presence of a central MPPT

    DEFF Research Database (Denmark)

    Sera, Dezso; Mathe, Laszlo; Blaabjerg, Frede

    2014-01-01

    in that the MIC should ensure the string voltage stability and MPP operation in presence of other MICs and ‘plain’ panels. It must also be transparent to the main inverters' MPPT, so that it can track during normal operation. In this paper, a system layout with local MPPT without voltage control is proposed...

  9. Design of Solar Street Lamp Control System Based on MPPT

    Science.gov (United States)

    Cui, Fengying

    This paper proposes a new solar street lamp control system which is composed of photovoltaic cell, controller, battery and load. In this system controller as the key part applies the microchip to achieve many functions. According to the nonlinear output characteristics of solar cell and the influence of environment, it uses the perturbation and observation (P&O) method to realize the maximum power point tracking (MPPT) and promotes the efficiency. In order to prolong the battery life the pulse width modulation (PWM) charge mode is selected to control the battery capacity and provent the battery from the state of over-charge and over-discharge. Meanwhile the function of temperature compensation, charge and discharge protection are set to improve the running safety and stability.

  10. MPPT Control Strategy of PV Based on Improved Shuffled Frog Leaping Algorithm under Complex Environments

    Directory of Open Access Journals (Sweden)

    Xiaohua Nie

    2017-01-01

    Full Text Available This work presents a maximum power point tracking (MPPT based on the particle swarm optimization (PSO improved shuffled frog leaping algorithm (PSFLA. The swarm intelligence algorithm (SIA has vast computing ability. The MPPT control strategies of PV array based on SIA are attracting considerable interests. Firstly, the PSFLA was proposed by adding the inertia weight factor w of PSO in standard SFLA to overcome the defect of falling into the partial optimal solutions and slow convergence speed. The proposed PSFLA algorithm increased calculation speed and excellent global search capability of MPPT. Then, the PSFLA was applied to MPPT to solve the multiple extreme point problems of nonlinear optimization. Secondly, for the problems of MPPT under complex environments, a new MPPT strategy of the PSFLA combined with recursive least square filtering was proposed to overcome the measurement noise effects on MPPT accuracy. Finally, the simulation comparisons between PSFLA and SFLA algorithm were developed. The experiment and comparison between PSLFA and PSO algorithm under complex environment were executed. The simulation and experiment results indicate that the proposed MPPT control strategy based on PSFLA can suppress the measurement noise effects effectively and improve the PV array efficiency.

  11. Comparative study of adaptive controller using MIT rules and Lyapunov method for MPPT standalone PV systems

    Science.gov (United States)

    Tariba, N.; Bouknadel, A.; Haddou, A.; Ikken, N.; Omari, Hafsa El; Omari, Hamid El

    2017-01-01

    The Photovoltaic Generator have a nonlinear characteristic function relating the intensity at the voltage I = f (U) and depend on the variation of solar irradiation and temperature, In addition, its point of operation depends directly on the load that it supplies. To fix this drawback, and to extract the maximum power available to the terminal of the generator, an adaptation stage is introduced between the generator and the load to couple the two elements as perfectly as possible. The adaptation stage is associated with a command called MPPT MPPT (Maximum Power Point Tracker) whose is used to force the PVG to operate at the MPP (Maximum Power Point) under variation of climatic conditions and load variation. This paper presents a comparative study between the adaptive controller for PV Systems using MIT rules and Lyapunov method to regulate the PV voltage. The Incremental Conductance (IC) algorithm is used to extract the maximum power from the PVG by calculating the voltage Vref, and the adaptive controller is used to regulate and track quickly the PV voltage. The two methods of the adaptive controller will be compared to prove their performance by using the PSIM tools and experimental test, and the mathematical model of step-up with PVG model will be presented.

  12. An Asymmetrical Fuzzy-Logic-Control-Based MPPT Algorithm for Photovoltaic Systems

    OpenAIRE

    Chun-Liang Liu; Jing-Hsiao Chen; Yi-Hua Liu; Zong-Zhen Yang

    2014-01-01

    In this paper, a fuzzy-logic-control (FLC) based maximum power point tracking (MPPT) algorithm for photovoltaic (PV) systems is proposed. The power variation and output voltage variation are chosen as inputs of the proposed FLC, which simplifies the calculation. Compared with the conventional perturb and observe (P&O) method, the proposed FLC-based MPPT can simultaneously improve the dynamic and steady state performance of the PV system. To further improve the performance of the proposed ...

  13. Optimization of a Fuzzy-Logic-Control-Based MPPT Algorithm Using the Particle Swarm Optimization Technique

    OpenAIRE

    Po-Chen Cheng; Bo-Rei Peng; Yi-Hua Liu; Yu-Shan Cheng; Jia-Wei Huang

    2015-01-01

    In this paper, an asymmetrical fuzzy-logic-control (FLC)-based maximum power point tracking (MPPT) algorithm for photovoltaic (PV) systems is presented. Two membership function (MF) design methodologies that can improve the effectiveness of the proposed asymmetrical FLC-based MPPT methods are then proposed. The first method can quickly determine the input MF setting values via the power–voltage (P–V) curve of solar cells under standard test conditions (STC). The second method uses the particl...

  14. MPPT Control Strategy of PV Based on Improved Shuffled Frog Leaping Algorithm under Complex Environments

    OpenAIRE

    Nie, Xiaohua; Nie, Haoyao

    2017-01-01

    This work presents a maximum power point tracking (MPPT) based on the particle swarm optimization (PSO) improved shuffled frog leaping algorithm (PSFLA). The swarm intelligence algorithm (SIA) has vast computing ability. The MPPT control strategies of PV array based on SIA are attracting considerable interests. Firstly, the PSFLA was proposed by adding the inertia weight factor w of PSO in standard SFLA to overcome the defect of falling into the partial optimal solutions and slow convergence ...

  15. Adaptive Fuzzy Logic based MPPT Control for PV System Under Partial Shading Condition

    OpenAIRE

    Choudhury, Subhashree; Rout, Pravat Kumar

    2016-01-01

    Partial shading causes power loss, hotspots and threatens the reliability of the Photovoltaic generation system. Moreover characteristic curves exhibit multiple peaks. Conventional MPPT techniques under this condition often fail to give optimum MPP. Focusing on the afore mentioned problem an attempt has been made to design an Adaptive Takagi-Sugeno Fuzzy Inference System based Fuzzy Logic Control MPPT.The mathematical model of PV array is simulated using in MATLAB/Simulink environment.Various...

  16. An Asymmetrical Fuzzy-Logic-Control-Based MPPT Algorithm for Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    Chun-Liang Liu

    2014-04-01

    Full Text Available In this paper, a fuzzy-logic-control (FLC based maximum power point tracking (MPPT algorithm for photovoltaic (PV systems is proposed. The power variation and output voltage variation are chosen as inputs of the proposed FLC, which simplifies the calculation. Compared with the conventional perturb and observe (P&O method, the proposed FLC-based MPPT can simultaneously improve the dynamic and steady state performance of the PV system. To further improve the performance of the proposed method, an asymmetrical membership function (MF concept is also proposed. Two design procedures are proposed to determine the universe of discourse (UOD of the input MF. Comparing with the proposed symmetrical FLC-based MPPT method, the transient time and the MPPT tracking accuracy are further improved by 42.8% and 0.06%, respectively.

  17. Comparative analysis of distributed MPPT controllers for partially shaded stand alone photovoltaic systems

    International Nuclear Information System (INIS)

    Muthuramalingam, M.; Manoharan, P.S.

    2014-01-01

    Highlights: • Analyzes the performance of ANN and ANFIS MPPT algorithms by stand alone PV system. • ISSBC with ANFIS can provide the overall efficiency higher than ANN. • CHBMLI integrate with SHE ANN modulation technique improve output voltage quality. • Simulation and hardware results show the ANFIS algorithm efficient than ANN algorithm. - Abstract: This paper presents a unique combination of an interleaved soft switched boost converter (ISSBC) run by a set of two photovoltaic panel (PV) with a distributed MPPT, suitable to guarantee MPPT even under partial shadowed conditions, managed by an adaptive neuro fuzzy inference system trained by the training data derived from a particle swarm optimization (PSO–ANFIS) unit. The ISSBC is followed by a, single phase cascaded H bridge five-level inverter (CHI) driven by the individual DC outputs of the ISSBC, with selective harmonic elimination scheme to eliminate typically the seventh order harmonics. A comparison of different intelligent distributed maximum power point tracking (MPPT) algorithms for photovoltaic (PV) system under partial shadow conditions is carried out. The use of the ISSBC guarantees mitigation of ripple and it is meant to handle higher currents with minimal switching losses. Simulation was carried out in the Matlab Simulink environment and an experimental verification with a scaled down model validated the proposed scheme. It has been thus established, by both simulation and experimental verification, that the PSO–ANFIS model of distributed MPPT scheme of control outperforms other schemes of control for MPPT

  18. MPPT-Based Control Algorithm for PV System Using iteration-PSO under Irregular shadow Conditions

    Directory of Open Access Journals (Sweden)

    M. Abdulkadir

    2017-02-01

    Full Text Available The conventional maximum power point tracking (MPPT techniques can hardly track the global maximum power point (GMPP because the power-voltage characteristics of photovoltaic (PV exhibit multiple local peaks in irregular shadow, and therefore easily fall into the local maximum power point. These conditions make it very challenging, and to tackle this deficiency, an efficient Iteration Particle Swarm Optimization (IPSO has been developed to improve the quality of solution and convergence speed of the traditional PSO, so that it can effectively track the GMPP under irregular shadow conditions. This proposed technique has such advantages as simple structure, fast response and strong robustness, and convenient implementation. It is applied to MPPT control of PV system in irregular shadow to solve the problem of multi-peak optimization in partial shadow. In order to verify the rationality of the proposed algorithm, however, recently the dynamic MPPT performance under varying irradiance conditions has been given utmost attention to the PV society. As the European standard EN 50530 which defines the recommended varying irradiance profiles, was released lately, the corresponding researchers have been required to improve the dynamic MPPT performance. This paper tried to evaluate the dynamic MPPT performance using EN 50530 standard. The simulation results show that iterative-PSO method can fast track the global MPP, increase tracking speed and higher dynamic MPPT efficiency under EN 50530 than the conventional PSO.

  19. Single-stage MPPT control realization for Aalborg inverter in photovoltaic system

    DEFF Research Database (Denmark)

    Zhang, Shuai; Wu, Weimin; Wang, Houqing

    2017-01-01

    In this paper, the single-stage Maximum Power Point Tracking (MPPT) control strategy for the Aalborg photovoltaic inverter is presented. Aalborg inverter has many advantages, such as high efficiency, wide range of input voltage, minimum voltage drop of the filtering inductors, etc. Nevertheless......, it is essentially a “half-bridge” inverter with two input sources, where one source works in MPPT mode, the other is out of control. If without the reasonable parameter design and the proper control, the bus-voltage of this inverter may change greatly, resulting in the serious power oscillation around maximum power...... that the proposed control strategy has good steady-state and dynamic performances....

  20. High Step-Up DC—DC Converter for AC Photovoltaic Module with MPPT Control

    Science.gov (United States)

    Sundar, Govindasamy; Karthick, Narashiman; Rama Reddy, Sasi

    2014-08-01

    This paper presents the high gain step-up BOOST converter which is essential to step up the low output voltage from PV panel to the high voltage according to the requirement of the application. In this paper a high gain BOOST converter with coupled inductor technique is proposed with the MPPT control. Without extreme duty ratios and the numerous turns-ratios of a coupled inductor this converter achieves a high step-up voltage-conversion ratio and the leakage energy of the coupled inductor is efficiently recycled to the load. MPPT control used to extract the maximum power from PV panel by controlling the Duty ratio of the converter. The PV panel, BOOST converter and the MPPT are modeled using Sim Power System blocks in MATLAB/SIMULINK environment. The prototype model of the proposed converter has been implemented with the maximum measured efficiency is up to 95.4% and full-load efficiency is 93.1%.

  1. A Novel MPPT Control Method of Thermoelectric Power Generation with Single Sensor

    Directory of Open Access Journals (Sweden)

    Tadashi Sakaguchi

    2013-04-01

    Full Text Available This paper proposes a novel Maximum Power Point Tracking (MPPT control method of thermoelectric power generation for the constant load. This paper reveals the characteristics and the internal resistance of thermoelectric power module (TM. Analyzing the thermoelectric power generation system with boost chopper by state space averaging method, the output voltage and current of TM are estimated by with only single current sensor. The proposed method can seek without calculating the output power of TM in this proposed method. The basic principle of the proposed MPPT control method is discussed, and then confirmed by digital computer simulation using PSIM. Simulation results demonstrate that the output voltage can track the maximum power point voltage by the proposed MPPT control method. The generated power of the TM is 0.36 W when the temperature difference is 35 °C. This is well accorded with the V-P characteristics.

  2. A Current Sensorless MPPT Control Method for a Stand-Alone-Type PV Generation System

    Science.gov (United States)

    Itako, Kazutaka; Mori, Takeaki

    In this paper, a current sensorless MPPT control method for a stand-alone-type PV generation system is proposed. This control method offers advantages of the simplified hardware configuration and the low cost, by using only one sensor to measure the PV output voltage. In the application to stand-alone-type with a battery load, the experimental results show that the estimated values of PV output current are accurate, and the use of the proposed MPPT control increases the PV generated energy by 16.3% compared to the conventional system. Furthermore, it is clarified that the proposed method has extremely high UUF (Useful utilization factor) of 98.7%.

  3. A Method of MPPT Control Based on Power Variable Step-size in Photovoltaic Converter System

    Directory of Open Access Journals (Sweden)

    Xu Hui-xiang

    2016-01-01

    Full Text Available Since the disadvantage of traditional MPPT algorithms of variable step-size, proposed power tracking based on variable step-size with the advantage method of the constant-voltage and the perturb-observe (P&O[1-3]. The control strategy modify the problem of voltage fluctuation caused by perturb-observe method, at the same time, introducing the advantage of constant-voltage method and simplify the circuit topology. With the theoretical derivation, control the output power of photovoltaic modules to change the duty cycle of main switch. Achieve the maximum power stabilization output, reduce the volatility of energy loss effectively, and improve the inversion efficiency[3,4]. Given the result of experimental test based theoretical derivation and the curve of MPPT when the prototype work.

  4. A Novel MPPT Control Method of Thermoelectric Power Generation with Single Sensor

    OpenAIRE

    Yamada, Hiroaki; Kimura, Koji; Hanamoto, Tsuyoshi; Ishiyama, Toshihiko; Sakaguchi, Tadashi; Takahashi, Tsuyoshi

    2013-01-01

    This paper proposes a novel Maximum Power Point Tracking (MPPT) control method of thermoelectric power generation for the constant load. This paper reveals the characteristics and the internal resistance of thermoelectric power module (TM). Analyzing the thermoelectric power generation system with boost chopper by state space averaging method, the output voltage and current of TM are estimated by with only single current sensor. The proposed method can seek without calculating the output powe...

  5. An Improved PSO-Based MPPT Control Strategy for Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    M. Abdulkadir

    2014-01-01

    Full Text Available This paper presents a control strategy proposed for power maximizing which is a critical mechanism to ensure power track is maximized. Many tracking algorithms have been proposed for this purpose. One of the more commonly used techniques is the incremental conductance method. In this paper, an improved particle swarm optimization- (IPSO- based MPPT technique for photovoltaic system operating under varying environmental conditions is proposed. The approach of linearly decreasing scheme for weighting factor and cognitive and social parameter is modified. The proposed control scheme can overcome deficiency and accelerate convergence of the IPSO-based MPPT algorithm. The approach is not only capable of tracking the maximum power point under uniform insolation state, but also able to find the maximum power point under fast changing nonuniform insolation conditions. The photovoltaic systematic process with control schemes is created using MATLAB Simulink to verify the effectiveness with several simulations being carried out and then compared with the conventional incremental conductance technique. Lastly, the effectiveness of the intended techniques is proven using real data obtained form previous literature. With the change in insolation and temperature portrait, it produces exceptional MPPT maximization. This shows that optimum performance is achieved using the intended method compared to the typical method.

  6. ANFIS-based estimation of PV module equivalent parameters: application to a stand-alone PV system with MPPT controller

    OpenAIRE

    KULAKSIZ, Ahmet Afşin

    2012-01-01

    The performance and system cost of photovoltaic (PV) systems can be improved by employing high-efficiency power conditioners with maximum power point tracking (MPPT) methods. Fast implementation and accurate operation of MPPT controllers can be realized by modeling the characteristics of PV modules, obtaining equivalent parameters. In this study, adaptive neuro-fuzzy inference systems (ANFISs) have been used to obtain 3 of the parameters in a single-diode model of PV cells, namely serie...

  7. Design of A Grid Integrated PV System with MPPT Control and Voltage Oriented Controller using MATLAB/PLECES

    Science.gov (United States)

    Soreng, Bineeta; Behera, Pradyumna; Pradhan, Raseswari

    2017-08-01

    This paper presents model of a grid-integrated photovoltaic array with Maximum Power Point Tracker (MPPT) and voltage oriented controller. The MPPT of the PV array is usually an essential part of PV system as MPPT helps the operating point of the solar array to align its maximum power point. In this model, the MPPT along with a DC-DC converter lets a PV generator to produce continuous power, despite of the measurement conditions. The neutral-point-clamped converter (NPC) with a boost converter raises the voltage from the panels to the DC-link. An LCL-filter smoothens the current ripple caused by the PWM modulation of the grid-side inverter. In addition to the MPPT, the system has two more two controllers, such as voltage controller and a current controller. The voltage control has a PI controller to regulate the PV voltage to optimal level by controlling the amount of current injected into the boost stage. Here, the grid-side converter transfers the power from the DC-link into the grid and maintains the DC-link voltage. Three-phase PV inverters are used for off-grid or designed to create utility frequency AC. The PV system can be connected in series or parallel to get the desired output power. To justify the working of this model, the grid-integrated PV system has been designed in MATLAB/PLECS. The simulation shows the P-V curve of implemented PV Array consisting 4 X 20 modules, reactive, real power, grid voltage and current.

  8. A power conditioning system for thermoelectric generator based on interleaved Boost converter with MPPT control

    DEFF Research Database (Denmark)

    Ni, L.-X; Sun, K.; Zhang, L.

    2011-01-01

    The thermoelectric generation (TEG) system has its special charactristics of high stablility, low voltage and high current output, which is different from PV modules. The power conditioning system and control schemes used in PV applications cannot be directly applied to TEG applications. A power...... maximum power from TEG by matching the load with internal resistance. Since the battery is usually employed as the load for TEG systems, the interleaved Boost converter operates in two different modes for battery charging: before the battery is fully charged, the system outputs the maximum power (MPPT...

  9. Modeling and Control of DC/DC Boost Converter using K-Factor Control for MPPT of Solar PV System

    DEFF Research Database (Denmark)

    Vangari, Adithya; Haribabu, Divyanagalakshmi; Sakamuri, Jayachandra N.

    2015-01-01

    is presented. Design of the passive elements of the boost converter as per the system specifications is also illustrated. The performance of the proposed K factor control method is verified with the simulations for MPPT on solar PV system at different atmospheric conditions. A new circuit based model for solar......This paper is focused on the design of a controller for the DC/DC boost converter using K factor control, which is based on modified PI control method, for maximum power point tracking (MPPT) of solar PV system. A mathematical model for boost converter based on small signal averaging approach...... PV array, which includes the effect of solar insolation and temperature on PV array output, for the application in power system transient simulations, is also presented. The performance of the PV array model is verified with simulations at different atmospheric conditions. A 160W PV module from BP...

  10. Dynamic modeling and performance evaluation of axial flux PMSG based wind turbine system with MPPT control

    Directory of Open Access Journals (Sweden)

    Vahid Behjat

    2014-12-01

    Full Text Available This research work develops dynamic model of a gearless small scale wind power generation system based on a direct driven single sided outer rotor AFPMSG with coreless armature winding. Dynamic modeling of the AFPMSG based wind turbine requires machine parameters. To this end, a 3D FEM model of the generator is developed and from magnetostatic and transient analysis of the FEM model, machine parameters are calculated and utilized in dynamic modeling of the system. A maximum power point tracking (MPPT-based FOC control approach is used to obtain maximum power from the variable wind speed. The simulation results show the proper performance of the developed dynamic model of the AFPMSG, control approach and power generation system.

  11. Optimal Design of MPPT Controllers for Grid Connected Photovoltaic Array System

    Science.gov (United States)

    Ebrahim, M. A.; AbdelHadi, H. A.; Mahmoud, H. M.; Saied, E. M.; Salama, M. M.

    2016-10-01

    Integrating photovoltaic (PV) plants into electric power system exhibits challenges to power system dynamic performance. These challenges stem primarily from the natural characteristics of PV plants, which differ in some respects from the conventional plants. The most significant challenge is how to extract and regulate the maximum power from the sun. This paper presents the optimal design for the most commonly used Maximum Power Point Tracking (MPPT) techniques based on Proportional Integral tuned by Particle Swarm Optimization (PI-PSO). These suggested techniques are, (1) the incremental conductance, (2) perturb and observe, (3) fractional short circuit current and (4) fractional open circuit voltage techniques. This research work provides a comprehensive comparative study with the energy availability ratio from photovoltaic panels. The simulation results proved that the proposed controllers have an impressive tracking response. The system dynamic performance improved greatly using the proposed controllers.

  12. Fuzzy Controller for a Voltage-Regulated Solar-Powered MPPT System for Hybrid Power System Applications

    Directory of Open Access Journals (Sweden)

    Jaw-Kuen Shiau

    2015-04-01

    Full Text Available This paper presents the design of a fuzzy-logic-based voltage-regulated solar power maximum power point tracking (MPPT system for applications involving hybrid power systems. The system contains a solar power system and battery as the primary and secondary power sources, respectively. The solar system alone supplies power to the electric motor and maintains the output voltage at a predetermined level when it has sufficient power. When the solar power is insufficient, the solar system is operated at its maximum power point (MPP and the battery is engaged to compensate for the insufficiency. First, a variant of the incremental conductance MPP condition was established. Under the MPP condition, the voltage-regulated MPPT system was formulated as a feedback control system, where the MPP condition and voltage regulation requirements were used as the system inputs. Next, a fuzzy controller was developed to perform the voltage-regulated MPPT function for the hybrid power system. A simulation model based on Matrix laboratory (MATLAB/SIMULINK (a block diagram environment for multi-domain simulation and model-based design and a piecewise linear electric circuit simulation (PLECS tool for controlling the dc motor velocity was developed to verify the voltage-regulated solar power MPPT system.

  13. A Single-Phase Multilevel PV Generation System with an Improved Ripple Correlation Control MPPT Algorithm

    Directory of Open Access Journals (Sweden)

    Manel Hammami

    2017-12-01

    Full Text Available The implementation of maximum power point tracking (MPPT schemes by the ripple correlation control (RCC algorithm is presented in this paper. A reference is made to single-phase single-stage multilevel photovoltaic (PV generation systems, when the inverter input variables (PV voltage and PV current have multiple low-frequency (ripple harmonics. The harmonic analysis is carried out with reference to a multilevel configuration consisting of an H-bridge inverter and level doubling network (LDN cell, leading to the multilevel inverter having double the output voltage levels as compared to the basic H-bridge inverter topology (i.e., five levels vs. three levels. The LDN cell is basically a half-bridge fed by a floating capacitor, with self-balancing voltage capability. The multilevel configuration introduces additional PV voltage and current low-frequency harmonics, perturbing the basic implementation of the RCC scheme (based on the second harmonic component, leading to malfunctioning. The proposed RCC algorithm employs the PV current and voltage harmonics at a specific frequency for the estimation of the voltage derivative of power dP/dV (or dI/dV, driving the PV operating point toward the maximum power point (MPP in a faster and more precise manner. The steady-state and transient performances of the proposed RCC-MPPT schemes have been preliminarily tested and compared using MATLAB/Simulink. Results have been verified by experimental tests considering the whole multilevel PV generation system, including real PV modules, multilevel insulated-gate bipolar transistor (IGBT inverters, and utility grids.

  14. Development of intelligent MPPT (maximum power point tracking) control for a grid-connected hybrid power generation system

    International Nuclear Information System (INIS)

    Hong, Chih-Ming; Ou, Ting-Chia; Lu, Kai-Hung

    2013-01-01

    A hybrid power control system is proposed in the paper, consisting of solar power, wind power, and a diesel-engine. To achieve a fast and stable response for the real power control, an intelligent controller was proposed, which consists of the Wilcoxon (radial basis function network) RBFN and the improved (Elman neural network) ENN for (maximum power point tracking) MPPT. The pitch angle control of wind power uses improved ENN controller, and the output is fed to the wind turbine to achieve the MPPT. The solar array is integrated with an RBFN control algorithm to track the maximum power. MATLAB (MATrix LABoratory)/Simulink was used to build the dynamic model and simulate the solar and diesel-wind hybrid power system. - Highlights: ► To achieve a fast and stable response for the real power control. ► The pitch control of wind power uses improved ENN (Elman neural network) controller to achieve the MPPT (maximum power point tracking). ► The RBFN (radial basis function network) can quickly and accurately track the maximum power output for PV (photovoltaic) array. ► MATLAB was used to build the dynamic model and simulate the hybrid power system. ► This method can reach the desired performance even under different load conditions

  15. DSP implementation of a PV system with GA-MLP-NN based MPPT controller supplying BLDC motor drive

    International Nuclear Information System (INIS)

    Akkaya, R.; Kulaksiz, A.A.; Aydogdu, O.

    2007-01-01

    This paper presents a brushless dc motor drive for heating, ventilating and air conditioning fans, which is utilized as the load of a photovoltaic system with a maximum power point tracking (MPPT) controller. The MPPT controller is based on a genetic assisted, multi-layer perceptron neural network (GA-MLP-NN) structure and includes a DC-DC boost converter. Genetic assistance in the neural network is used to optimize the size of the hidden layer. Also, for training the network, a genetic assisted, Levenberg-Marquardt (GA-LM) algorithm is utilized. The off line GA-MLP-NN, trained by this hybrid algorithm, is utilized for online estimation of the voltage and current values in the maximum power point. A brushless dc (BLDC) motor drive system that incorporates a motor controller with proportional integral (PI) speed control loop is successfully implemented to operate the fans. The digital signal processor (DSP) based unit provides rapid achievement of the MPPT and current control of the BLDC motor drive. The performance results of the system are given, and experimental results are presented for a laboratory prototype of 120 W

  16. New current control based MPPT technique for single stage grid connected PV systems

    International Nuclear Information System (INIS)

    Jain, Sachin; Agarwal, Vivek

    2007-01-01

    This paper presents a new maximum power point tracking algorithm based on current control for a single stage grid connected photovoltaic system. The main advantage of this algorithm comes from its ability to predict the approximate amplitude of the reference current waveform or power that can be derived from the PV array with the help of an intermediate variable β. A variable step size for the change in reference amplitude during initial tracking helps in fast tracking. It is observed that if the reference current amplitude is greater than the array capacity, the system gets unstable (i.e. moves into the positive slope region of the p-v characteristics of the array). The proposed algorithm prevents the PV system from entering the positive slope region of the p-v characteristics. It is also capable of restoring stability if the system goes unstable due to a sudden environmental change. The proposed algorithm has been tested on a new single stage grid connected PV configuration recently developed by the authors to feed sinusoidal current into the grid. The system is operated in a continuous conduction mode to realize advantages such as low device current stress, high efficiency and low EMI. A fast MPPT tracker with single stage inverter topology operating in CCM makes the overall system highly efficient. Specific cases of the system, operating in just discontinuous current mode and discontinuous current mode and their relative merits and demerits are also discussed

  17. A more rigorous description of the multiplierless MPPT principle.

    OpenAIRE

    Romeo, Giovanni

    2010-01-01

    This note refers to the article “Achieve MPPT control without power calculation “(Electronic Design, November 05 2009, p. 53, http://electronicdesign.com/article/power/achieve_mppt_control_without_power_calculation.aspx) giving some mathematical justification about the multiplier disuse and the use of a synchronous modulation-demodulation to implement a MPPT.

  18. A modified P&O MPPT algorithm for single-phase PV systems based on deadbeat control

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede

    2012-01-01

    A modified perturb and observe (P&O) algorithm is presented to improve maximum power point tracking (MPPT) performance of photovoltaic (PV) systems. This modified algorithm is applied to a single-phase PV system based on deadbeat control in order to test the tracking accuracy and its impact...... on the reliability of the whole system. Both simulations and experimental results show that the proposed algorithm offers a fast response as well as smaller steady-state oscillations even under low irradiance condition compared with classical methods....

  19. Design of High Efficient MPPT Solar Inverter

    Directory of Open Access Journals (Sweden)

    Sunitha K. A.

    2017-01-01

    Full Text Available This work aims to design a High Efficient Maximum Power Point Tracking (MPPT Solar Inverter. A boost converter is designed in the system to boost the power from the photovoltaic panel. By this experimental setup a room consisting of 500 Watts load (eight fluorescent tubes is completely controlled. It is aimed to decrease the maintenance cost. A microcontroller is introduced for tracking the P&O (Perturb and Observe algorithm used for tracking the maximum power point. The duty cycle for the operation of the boost convertor is optimally adjusted by using MPPT controller. There is a MPPT charge controller to charge the battery as well as fed to inverter which runs the load. Both the P&O scheme with the fixed variation for the reference current and the intelligent MPPT algorithm were able to identify the global Maximum power point, however the performance of the MPPT algorithm was better.

  20. Analysis and MPPT control of a wind-driven three-phase induction generator feeding single-phase utility grid

    Directory of Open Access Journals (Sweden)

    Krishnan Arthishri

    2017-05-01

    Full Text Available In this study, a three-phase diode bridge rectifier and a single-phase voltage source inverter topology has been proposed for feeding single-phase utility grid employing a three-phase induction generator fed from wind energy. A self-excited induction generator configuration has been chosen for wide speed operation of wind turbine system, which gives the scope for extracting maximum power available in the wind. In addition to maximum power point tracking (MPPT, the generator can be loaded to its rated capacity for feeding single-phase utility grid using a three-phase induction machine, whereas it is not possible with existing configurations because of the absence of power converters. For the proposed system, MPPT algorithm has been devised by continuously monitoring the grid current and a proportional resonant controller has been employed for grid synchronisation of voltage source inverter with single-phase grid. A MATLAB/Simulink model of the proposed system has been developed to ascertain its successful working by predetermining the overall performance characteristics. The present proposal has also been tested with sag, swell and distortion in the grid voltage. The control strategy has been implemented using field programmable gate array (FPGA controller with modularised programming approach. The efficacy of the system has been demonstrated with the results obtained from an experimental set-up in the laboratory.

  1. Performance and Analysis of an Asynchronous Motor Drive with a New Modified Type-2 Neuro Fuzzy Based MPPT Controller Under Variable Irradiance and Variable Temperature

    Directory of Open Access Journals (Sweden)

    Pakkiraiah B.

    2017-02-01

    Full Text Available In the present research, we have developed a new modified Type 2 neuro fuzzy (T2NF based MPPT controller, which combines the advantages of fractional open circuit voltage (FCV, variable step and optimized P&O algorithm. It leads to a faster and better tracking and lower oscillations around the MPP to contribute higher efficiency. The simulation result shows an efficiency of 96.41 %, an improvement of 2 ms is observed in the starting characteristics. The above concept has been extended to single phase AC photovoltaic system with improvement of 15 % in its performance. It has benefits of high efficiency and low harmonic distortion at output voltage waveform. Here DC-DC boost converter and space vector modulation based inverter are used to provide the required supply to the load. The proposed T2NF based MPPT improves the system efficiency even at abnormal weather conditions. Here a lot of reduction in torque and current ripple contents is obtained with the help of T2NF based MPPT for an asynchronous motor drive. Also the better performance of an asynchronous motor drive is analyzed with the comparison of conventional and proposed MPPT controller using Matlab-simulation results. Practical validations are also carried out and tabulated.

  2. A Comparison Study between Two MPPT Control Methods for a Large Variable-Speed Wind Turbine under Different Wind Speed Characteristics

    Directory of Open Access Journals (Sweden)

    Dongran Song

    2017-05-01

    Full Text Available Variable speed wind turbines (VSWTs usually adopt a maximum power point tracking (MPPT method to optimize energy capture performance. Nevertheless, obtained performance offered by different MPPT methods may be affected by the impact of wind turbine (WT’s inertia and wind speed characteristics and it needs to be clarified. In this paper, the tip speed ratio (TSR and optimal torque (OT methods are investigated in terms of their performance under different wind speed characteristics on a 1.5 MW wind turbine model. To this end, the TSR control method based on an effective wind speed estimator and the OT control method are firstly presented. Then, their performance is investigated and compared through simulation test results under different wind speeds using Bladed software. Comparison results show that the TSR control method can capture slightly more wind energy at the cost of high component loads than the other one under all wind conditions. Furthermore, it is found that both control methods present similar trends of power reduction that is relevant to mean wind speed and turbulence intensity. From the obtained results, we demonstrate that, to further improve MPPT capability of large VSWTs, other advanced control methods using wind speed prediction information need to be addressed.

  3. Multi-Layer Artificial Neural Networks Based MPPT-Pitch Angle Control of a Tidal Stream Generator

    Directory of Open Access Journals (Sweden)

    Khaoula Ghefiri

    2018-04-01

    Full Text Available Artificial intelligence technologies are widely investigated as a promising technique for tackling complex and ill-defined problems. In this context, artificial neural networks methodology has been considered as an effective tool to handle renewable energy systems. Thereby, the use of Tidal Stream Generator (TSG systems aim to provide clean and reliable electrical power. However, the power captured from tidal currents is highly disturbed due to the swell effect and the periodicity of the tidal current phenomenon. In order to improve the quality of the generated power, this paper focuses on the power smoothing control. For this purpose, a novel Artificial Neural Network (ANN is investigated and implemented to provide the proper rotational speed reference and the blade pitch angle. The ANN supervisor adequately switches the system in variable speed and power limitation modes. In order to recover the maximum power from the tides, a rotational speed control is applied to the rotor side converter following the Maximum Power Point Tracking (MPPT generated from the ANN block. In case of strong tidal currents, a pitch angle control is set based on the ANN approach to keep the system operating within safe limits. Two study cases were performed to test the performance of the output power. Simulation results demonstrate that the implemented control strategies achieve a smoothed generated power in the case of swell disturbances.

  4. Single Stage String Inverter for Gridconnected Photovoltaic System with Modified Perturb and Observe (P&O Fuzzy Logic Control(FLC-based MPPT Technique

    Directory of Open Access Journals (Sweden)

    S.Z.Mohammad Noor

    2016-06-01

    Full Text Available This paper presents an implementation of Single-phase Single stage String inverter for Grid connected Photovoltaic (PV system. The proposed system uses Modified Perturb and Observe (P&O algorithm implemented using Fuzzy Logic Control (FLC as Maximum Power Point Tracking (MPPT. The inverter is designed for 340W system using two series of STP170s24/Ac PV modules. The MPPT unit keeps tracking the maximum power from the PV array by changing the modulation index and the phase angle of inverter’s output voltage. The simulation model is developed using Matlab/Simulink to evaluate the performance of the converter. Selected experimental results are also presented in this paper.

  5. Design of Incremental Conductance Sliding Mode MPPT Control Applied by Integrated Photovoltaic and Proton Exchange Membrane Fuel Cell System under Various Operating Conditions for BLDC Motor

    Directory of Open Access Journals (Sweden)

    Jehun Hahm

    2015-01-01

    Full Text Available This paper proposes an integrated photovoltaic (PV and proton exchange membrane fuel cell (PEMFC system for continuous energy harvesting under various operating conditions for use with a brushless DC motor. The proposed scheme is based on the incremental conductance (IncCond algorithm combined with the sliding mode technique. Under changing atmospheric conditions, the energy conversion efficiency of a PV array is very low, leading to significant power losses. Consequently, increasing efficiency by means of maximum power point tracking (MPPT is particularly important. To manage such a hybrid system, control strategies need to be established to achieve the aim of the distributed system. Firstly, a Matlab/Simulink based model of the PV and PEMFC is developed and validated, as well as the incremental conductance sliding (ICS MPPT technique; then, different MPPT algorithms are employed to control the PV array under nonuniform temperature and insolation conditions, to study these algorithms effectiveness under various operating conditions. Conventional techniques are easy to implement but produce oscillations at MPP. Compared to these techniques, the proposed technique is more efficient; it produces less oscillation at MPP in the steady state and provides more precise tracking.

  6. Brushless DC motor drives supplied by PV power system based on Z-source inverter and FL-IC MPPT controller

    International Nuclear Information System (INIS)

    Mozaffari Niapour, S.A.KH.; Danyali, S.; Sharifian, M.B.B.; Feyzi, M.R.

    2011-01-01

    Highlights: → Employing the BLDC motor in water pumping systems. → Utilizing the ZSI as a single-stage power converter in the PV water pumping systems based on BLDC motor. → Improvement of the conventional IC MPPT method with the fuzzy logic control scheme to save more energy from the PV array. → Taking the advantages of the DTC drive of the BLDC motor. → Optimizing the water pumping system speed response characteristic by PSO. - Abstract: This paper discusses operation performance of a water pumping system consist of a brushless dc (BLDC) motor coupled a centrifugal pump and accompanying a Z-source inverter (ZSI) fed by a photovoltaic (PV) array, to be improved. Despite conventional double-stage power converters, this paper proposes utilizing a single-stage ZSI to extract the maximum power of the PV array and supply the BLDC motor simultaneously. Utilizing the ZSI provides some inherent advantages such as high efficiency and low cost, which is very promising for PV systems due to its novel voltage buck/boost capability. In addition, in order to precisely perform the maximum power point tracking (MPPT) of the PV array the fuzzy logic-incremental conductance (FL-IC) MPPT scheme is proposed. The proposed FL-IC MPPT scheme provides enough modification to the conventional IC method to enjoy an appropriate variable step size MPPT control signal for the ZSI. Moreover, direct torque control (DTC) is found more effective in comparison with hysteresis current control with current shaping to drive the BLDC motor, because it benefits from faster torque response, reduced torque ripple, less sensitivity to parameters variations, and simple implementation. In the mean time, due to the frequently variations of the PV power generation; delivered mechanical power to the centrifugal pump is variable. Thus, the BLDC motor should be driven with variable reference speed. In order to improve the speed transient response of the BLDC motor and enhance the energy saving aspect of

  7. Adherence to two methods of education and metabolic control in ...

    African Journals Online (AJOL)

    . VRG Herrera, HM Zerón, MRM Alcántara. Abstract. BACKGROUND: Education in diabetes optimizes metabolic control, prevents acute and chronic complications, and improves quality of life. Our main objective was to evaluate if a better ...

  8. Evaluation of two methods in controlling dental treatment water contamination.

    Science.gov (United States)

    Bansal, Ritu; Puttaiah, Raghunath; Harris, Robert; Reddy, Anil

    2011-03-01

    Dental unit water systems are contaminated with biofilms that amplify bacterial counts in dental treatment water in excess of a million colony forming units per milliliter (cfu/ml). The Centers for Disease Control and Prevention and the American Dental Association have agreed that the maximum allowable contamination of dental treatment water not exceed 500 cfu/ml. This study was conducted to evaluate two protocols in controlling contamination of dental unit water systems and dental treatment water. Both methods used an antimicrobial self-dissolving chlorine dioxide (ClO₂) tablet at a high concentration (50 ppm) to shock the dental unit water system biofilms initially followed by periodic exposure. To treat dental treatment source water for patient care, 3 parts per million (ppm) ClO₂ in municipal/tap water was compared to use of a citrus botanical extract dissolved in municipal water. Heterotrophic microbial counts of effluent water and laser scanning confocal microscopy were performed to evaluate effects of the two treatments. Results from this study indicated that both treatments were effective in controlling biofilm contamination and reducing heterotrophic plate counts Contemp Dent Pract 2011;12(2):73-83. Source of support: Nil Conflict of interest: None declared.

  9. A Newton-Based Extremum Seeking MPPT Method for Photovoltaic Systems with Stochastic Perturbations

    OpenAIRE

    Li, Heng; Peng, Jun; Liu, Weirong; Huang, Zhiwu; Lin, Kuo-Chi

    2014-01-01

    Microcontroller based maximum power point tracking (MPPT) has been the most popular MPPT approach in photovoltaic systems due to its high flexibility and efficiency in different photovoltaic systems. It is well known that PV systems typically operate under a range of uncertain environmental parameters and disturbances, which implies that MPPT controllers generally suffer from some unknown stochastic perturbations. To address this issue, a novel Newton-based stochastic extremum seeking MPPT me...

  10. A New MPPT Control for Photovoltaic Panels by Instantaneous Maximum Power Point Tracking

    Science.gov (United States)

    Tokushima, Daiki; Uchida, Masato; Kanbei, Satoshi; Ishikawa, Hiroki; Naitoh, Haruo

    This paper presents a new maximum power point tracking control for photovoltaic (PV) panels. The control can be categorized into the Perturb and Observe (P & O) method. It utilizes instantaneous voltage ripples at PV panel output terminals caused by the switching of a chopper connected to the panel in order to identify the direction for the maximum power point (MPP). The tracking for the MPP is achieved by a feedback control of the average terminal voltage of the panel. Appropriate use of the instantaneous and the average values of the PV voltage for the separate purposes enables both the quick transient response and the good convergence with almost no ripples simultaneously. The tracking capability is verified experimentally with a 2.8 W PV panel under a controlled experimental setup. A numerical comparison with a conventional P & O confirms that the proposed control extracts much more power from the PV panel.

  11. Impact of modified perturb and observe control on MPPT of PV/battery fed three - port DC‐DC converter

    Directory of Open Access Journals (Sweden)

    Venmathi Mahendran

    2017-07-01

    Full Text Available This paper presents the modified perturb and observe (P&O maximum power point tracking (MPPT method for photovoltaic (PV fed three-port DC‐DC converter in PV/battery hybrid system. The proposed MPPT technique reduces the drift problem which occurs in the conventional MPPT methods by including the data of change in current (ΔI in addition to the data used in the conventional P&O algorithm. The drift phenomenon and its effects are clearly demonstrated in this paper. The ability of the proposed P&O method to address this issue is proved by comparing the conventional P&O algorithm in different modes of operation. The performance assessment includes peak overshoot, settling time, MPP ratio and stability. The experimental validation was implemented using DSPIC30F4011 microcontroller. From the analysis and results, it could be seen that the modified P&O showed better performance in terms of accuracy in tracking the maximum power, less tracking time, high MPP ratio and reduced drift in the changing weather conditions.

  12. A MPPT Algorithm Based PV System Connected to Single Phase Voltage Controlled Grid

    Science.gov (United States)

    Sreekanth, G.; Narender Reddy, N.; Durga Prasad, A.; Nagendrababu, V.

    2012-10-01

    Future ancillary services provided by photovoltaic (PV) systems could facilitate their penetration in power systems. In addition, low-power PV systems can be designed to improve the power quality. This paper presents a single-phase PV systemthat provides grid voltage support and compensation of harmonic distortion at the point of common coupling thanks to a repetitive controller. The power provided by the PV panels is controlled by a Maximum Power Point Tracking algorithm based on the incremental conductance method specifically modified to control the phase of the PV inverter voltage. Simulation and experimental results validate the presented solution.

  13. MPPT for Photovoltaic Modules via Newton-Like Extremum Seeking Control

    Directory of Open Access Journals (Sweden)

    Ramon Leyva

    2012-07-01

    Full Text Available The paper adapts the Newton-like Extremum-Seeking Control technique to extract the maximum power from photovoltaic panels. This technique uses the gradient and Hessian of the panel characteristic in order to approximate the operating point to its optimum. The paper describes in detail the gradient and Hessian estimations carried out by means of sinusoidal dithering signals. Furthermore, we compare the proposed technique with the common Extremum Seeking Control that only uses the gradient. The comparison is done by means of PSIM simulations and it shows the different transient behaviors and the faster response of the Newton-like Extremum-Seeking Control solution.

  14. A Power Conditioning Stage Based on Analog-Circuit MPPT Control and a Superbuck Converter for Thermoelectric Generators in Spacecraft Power Systems

    Science.gov (United States)

    Sun, Kai; Wu, Hongfei; Cai, Yan; Xing, Yan

    2014-06-01

    A thermoelectric generator (TEG) is a very important kind of power supply for spacecraft, especially for deep-space missions, due to its long lifetime and high reliability. To develop a practical TEG power supply for spacecraft, a power conditioning stage is indispensable, being employed to convert the varying output voltage of the TEG modules to a definite voltage for feeding batteries or loads. To enhance the system reliability, a power conditioning stage based on analog-circuit maximum-power-point tracking (MPPT) control and a superbuck converter is proposed in this paper. The input of this power conditioning stage is connected to the output of the TEG modules, and the output of this stage is connected to the battery and loads. The superbuck converter is employed as the main circuit, featuring low input current ripples and high conversion efficiency. Since for spacecraft power systems reliable operation is the key target for control circuits, a reset-set flip-flop-based analog circuit is used as the basic control circuit to implement MPPT, being much simpler than digital control circuits and offering higher reliability. Experiments have verified the feasibility and effectiveness of the proposed power conditioning stage. The results show the advantages of the proposed stage, such as maximum utilization of TEG power, small input ripples, and good stability.

  15. Fuzzy Logic Based MPPT Controller for a Small Wind Turbine System

    DEFF Research Database (Denmark)

    Petrila, Diana; Blaabjerg, Frede; Muntean, Nicolae

    2012-01-01

    /Δω. The change of reference generator current (ΔI*) is the output variable. For small power applications, when the turbine inertia is relatively small, and the wind speed changes continuously, it is important to consider the transients in order to develop an accurate theoretical model and to attain optimal...... operation. Therefore, the mechanical power (Pm) is composed of the generator mechanical (input) power (Pg) plus the dynamic power, resulting in the dynamic power versus rotating speed curve. The controller is able to track the maximum power point for changing wind conditions, and is robust with respect...

  16. Comparison of four MPPT techniques for PV systems

    Energy Technology Data Exchange (ETDEWEB)

    Atik, L., E-mail: lotfi.atik@univ-usto.dz; Ternifi, Z. T. [University of science and technology of Oran, USTO, LDDE, Oran (Algeria); Université de Lorraine, LMOPS, EA 4423, 57070 Metz (France); Petit, P.; Sawicki, J. P.; Aillerie, M., E-mail: aillerie@metz.supelec.fr [Université de Lorraine, LMOPS, EA 4423, 57070 Metz (France); CentraleSupélec, LMOPS, 57070 Metz (France); Bachir, G. [University of science and technology of Oran, USTO, LDDE, Oran (Algeria)

    2016-07-25

    The working behavior of a module / PV array is non-linear and highly dependent on working conditions. As a given condition, there is only one point at which the level of available power at its output is maximum. This point varies with time, enlightenment and temperature. To ensure optimum operation, the use of MPPT control allows us to extract the maximum power. This paper presents a comparative study of four widely-adopted MPPT algorithms, such as Perturb and Observe, Incremental Conductance, Measurements of the variation of the open circuit voltage or of the short-circuit current. Their performance is evaluated using, for all these techniques. In particular, this study compares the behaviors of each technique in presence of solar irradiation variations and temperature fluctuations. These MPPT techniques will be compared using the Matlab / Simulink tool.

  17. Comparison of four MPPT techniques for PV systems

    Science.gov (United States)

    Atik, L.; Petit, P.; Sawicki, J. P.; Ternifi, Z. T.; Bachir, G.; Aillerie, M.

    2016-07-01

    The working behavior of a module / PV array is non-linear and highly dependent on working conditions. As a given condition, there is only one point at which the level of available power at its output is maximum. This point varies with time, enlightenment and temperature. To ensure optimum operation, the use of MPPT control allows us to extract the maximum power. This paper presents a comparative study of four widely-adopted MPPT algorithms, such as Perturb and Observe, Incremental Conductance, Measurements of the variation of the open circuit voltage or of the short-circuit current. Their performance is evaluated using, for all these techniques. In particular, this study compares the behaviors of each technique in presence of solar irradiation variations and temperature fluctuations. These MPPT techniques will be compared using the Matlab / Simulink tool.

  18. A Newton-Based Extremum Seeking MPPT Method for Photovoltaic Systems with Stochastic Perturbations

    Directory of Open Access Journals (Sweden)

    Heng Li

    2014-01-01

    Full Text Available Microcontroller based maximum power point tracking (MPPT has been the most popular MPPT approach in photovoltaic systems due to its high flexibility and efficiency in different photovoltaic systems. It is well known that PV systems typically operate under a range of uncertain environmental parameters and disturbances, which implies that MPPT controllers generally suffer from some unknown stochastic perturbations. To address this issue, a novel Newton-based stochastic extremum seeking MPPT method is proposed. Treating stochastic perturbations as excitation signals, the proposed MPPT controller has a good tolerance of stochastic perturbations in nature. Different from conventional gradient-based extremum seeking MPPT algorithm, the convergence rate of the proposed controller can be totally user-assignable rather than determined by unknown power map. The stability and convergence of the proposed controller are rigorously proved. We further discuss the effects of partial shading and PV module ageing on the proposed controller. Numerical simulations and experiments are conducted to show the effectiveness of the proposed MPPT algorithm.

  19. Desarrollo de una aplicación en Matlab para la evaluación de algoritmos MPPT y GMPPT

    OpenAIRE

    Micolau Subirón, Enric

    2016-01-01

    En el present projecte s’ha desenvolupat una aplicació per la avaluació de algoritmes MPPT y GMPPT utilitzant el programa MATLAB SIMULINK. L’aplicació que permet la simulació d’un sistema fotovoltaic senzill, compost per un mòdul fotovoltaic, convertidor DC-DC, Algoritme de control MPPT i una carrega resistiva. Posteriorment, s’han programat set algoritmes MPPT diferents, per a la seva simulació. Finalment, es compararan els resultats de la avaluació dels MPPT que ens permetrà escollir el mè...

  20. Integrated module inverter using a zeta DC-DC converter with feedforward MPPT (Maximum Power Point Tracking) control; Inversor modulo integrado utilizando um conversor CC-CC zeta com controle MPPT feedforward

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Henrique Fioravanti Miguel

    2009-08-15

    This work presents the study and development of a processing power system that could be used in the connection of renewable energy sources to commercial power grid. The system consists of a ZETA converter associated with a bridge inverter operating at low frequency. The Zeta converter, operating in discontinuous conduction mode (DCM), plays the main role in this arrangement, producing a rectified sinusoidal current waveform synchronized with the electric grid. The function of the full-bridge inverter, connected in cascade with the Zeta converter, is to reverse every 180 deg the current generated by the Zeta converter. Initially it presents the analysis of the Zeta converter operating in DCM, as well as a design criterion. Following by the control strategy and the experimental results for the proposed system are presented and discussed. (author)

  1. Simple Moving Voltage Average Incremental Conductance MPPT Technique with Direct Control Method under Nonuniform Solar Irradiance Conditions

    OpenAIRE

    Ali, Amjad; Li, Wuhua; He, Xiangning

    2015-01-01

    A new simple moving voltage average (SMVA) technique with fixed step direct control incremental conductance method is introduced to reduce solar photovoltaic voltage (VPV) oscillation under nonuniform solar irradiation conditions. To evaluate and validate the performance of the proposed SMVA method in comparison with the conventional fixed step direct control incremental conductance method under extreme conditions, different scenarios were simulated. Simulation results show that in most cases...

  2. Simple Moving Voltage Average Incremental Conductance MPPT Technique with Direct Control Method under Nonuniform Solar Irradiance Conditions

    Directory of Open Access Journals (Sweden)

    Amjad Ali

    2015-01-01

    Full Text Available A new simple moving voltage average (SMVA technique with fixed step direct control incremental conductance method is introduced to reduce solar photovoltaic voltage (VPV oscillation under nonuniform solar irradiation conditions. To evaluate and validate the performance of the proposed SMVA method in comparison with the conventional fixed step direct control incremental conductance method under extreme conditions, different scenarios were simulated. Simulation results show that in most cases SMVA gives better results with more stability as compared to traditional fixed step direct control INC with faster tracking system along with reduction in sustained oscillations and possesses fast steady state response and robustness. The steady state oscillations are almost eliminated because of extremely small dP/dV around maximum power (MP, which verify that the proposed method is suitable for standalone PV system under extreme weather conditions not only in terms of bus voltage stability but also in overall system efficiency.

  3. Development of Flexible Active Power Control Strategies for Grid-Connected Photovoltaic Inverters by Modifying MPPT Algorithms

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2017-01-01

    As the penetration level of grid-connected PV systems increases, more advanced control functionality is demanded. In order to ensure smooth and friendly grid integration as well as enable more PV installations, the power generated by PV systems needs to be flexible and capable of: 1) limiting...... strategies for grid-connected PV inverters by modifying maximum power point tracking algorithms, where the PV power is regulated by changing the operating point of the PV system. In this way, no extra equipment is needed, being a cost-effective solution. Experiments on a 3-kW grid-connected PV system have...

  4. BICO MPPT: A Faster Maximum Power Point Tracker and Its Application for Photovoltaic Panels

    OpenAIRE

    Malek, Hadi; Chen, YangQuan

    2014-01-01

    This paper develops a maximum power point tracking (MPPT) algorithm to optimize photovoltaic (PV) array performance and make it more compatible to rapidly varying weather conditions. In particular, a novel extremum seeking controller (ESC), which uses a Bode ideal cutoff (BICO) filter in its structure, is designed and tested on a simulated PV array. The new algorithm is compared against the commonly used ESC MPPT algorithm with first-order filters. The BICO extremum seeking controlle...

  5. A Variable Incremental Conductance MPPT Algorithm Applied to Photovoltaic Water Pumping System

    OpenAIRE

    S. Abdourraziq; R. El Bachtiri

    2015-01-01

    The use of solar energy as a source for pumping water is one of the promising areas in the photovoltaic (PV) application. The energy of photovoltaic pumping systems (PVPS) can be widely improved by employing an MPPT algorithm. This will lead consequently to maximize the electrical motor speed of the system. This paper presents a modified incremental conductance (IncCond) MPPT algorithm with direct control method applied to a standalone PV pumping system. The influence of ...

  6. MPPT for PM wind generator using gradient approximation

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Ying-Yi; Lu, Shiue-Der; Chiou, Ching-Sheng [Department of Electrical Engineering, Chung Yuan Christian University, 200, Chung-Pei Road, Chung Li 320 (China)

    2009-01-15

    This paper applies new maximum-power-point tracking (MPPT) algorithms to a wind-turbine generator system (WTGS). In this paper, the WTGS is a direct-drive system and includes the wind-turbine, permanent-magnet (PM) synchronous generator, three-phase full bridge rectifier, buck-boost converter and load. The new MPPT method uses gradient approximation (GA) algorithm. Three methods based on GA for achieving MPPT are discussed in this paper: (1) full-sensor control with anemometer and tachometer, (2) rule-based method and (3) adaptive duty cycle method. The third method has merits of no PID parameters, proportional constant, anemometer, tachometer and characteristics of WTGS required. This method enables the permanent-magnet synchronous generator (PMSG) to operate at variable speeds to achieve good performance. Simulation results show that the tip-speed ratio (TSR) and power coefficient obtained by the adaptive duty cycle method with GA can be almost identical to the optimal values. (author)

  7. Adherence to Two Methods of Education and Metabolic Control in Type 2 Diabetics.

    Science.gov (United States)

    Gutiérrez Herrera, Verónica R; Zerón, Hugo Mendieta; Mendieta Alcántara, Martha R

    2015-04-01

    Education in diabetes optimizes metabolic control, prevents acute and chronic complications, and improves quality of life. Our main objective was to evaluate if a better metabolic control is achieved in diabetic patients undergoing a program of intensive interactive care than in those with traditional care and written information. Patients with type 2 diabetes mellitus (T2DM), aged 20-60 years, education level at least of primary school, serum creatinine ≤ 2.5 mg/dl, self-sufficient and HbA1c ≥ 7.1% were allocated in two groups of education, 1) minimal education (MEG) and 2) full education (FEG). The MEG patients followed predefined diet; FEG patients chose the diet by selecting foods from each group in a list of matches, teaching them to count nutrients, kilocalories (kcal) and percentage of nutrients. A follow-up of 31 patients in each group was obtained. The proportion of patients who had initial adherence was 13.33% in the MEG group and 9.67% in the FEG group while, at the end of the study, these percentages were of 73.3% and 58.38% respectively. The final HbA1c decreased in both groups, with or without good adherence. The FEG group had a higher decline in the values of cholesterol (p = 0.036) and LDL (p = 0.002) than the MEG group. Education programs in T2DM contribute to a decrease in HbA1c within six months, but an intensive program is more effective in reducing cholesterol and LDL.

  8. A Simple MPPT Algorithm for Novel PV Power Generation System by High Output Voltage DC-DC Boost Converter

    DEFF Research Database (Denmark)

    Sanjeevikumar, Padmanaban; Grandi, Gabriele; Wheeler, Patrick

    2015-01-01

    This paper presents the novel topology of Photo Voltaic (PV) power generation system with simple Maximum Power Point Tracking (MPPT) algorithm in voltage operating mode. Power circuit consists of high output voltage DC-DC boost converter which maximizes the output of PV panel. Usually traditional...... substantially improves the high output-voltage by a simple MPPT closed loop proportional-integral (P-I) controller, and requires only two sensor for feedback needs. The complete numerical model of the converter circuit along with PV MPPT algorithm is developed in numerical simulation (Matlab/Simulink) software...

  9. Thermoelectric Generator Emulator for MPPT Testing

    DEFF Research Database (Denmark)

    Man, Elena Anamaria; Sera, Dezso; Máthé, Lászlo

    2015-01-01

    This paper presents a novel approach to use a DC power supply as a thermoelectric generator (TEG) emulator to perform static and dynamic maximum power point tracking (MPPT). First, the electrical characterization of a calcium-manganese-oxide module is performed on a TEG test rig. Afterwards...

  10. Improved Fractional Order VSS Inc-Cond MPPT Algorithm for Photovoltaic Scheme

    Directory of Open Access Journals (Sweden)

    R. Arulmurugan

    2014-01-01

    Full Text Available Nowadays a hot topic among the research community is the harnessing energy from the free sunlight which is abundant and pollution-free. The availability of cheap solar photovoltaic (PV modules has to harvest solar energy with better efficiency. The nature of solar modules is nonlinear and therefore the proper impedance matching is essential. The proper impedance matching ensures the extraction of the maximum power from solar PV module. Maximum power point tracking (MPPT algorithm is acting as a significant part in solar power generating system because it varies in the output power from a PV generating set for various climatic conditions. This paper suggested a new improved work for MPPT of PV energy system by using the optimized novel improved fractional order variable step size (FOVSS incremental conductance (Inc-Cond algorithm. The new proposed controller combines the merits of both improved fractional order (FO and variable step size (VSS Inc-Cond which is well suitable for design control and execution. The suggested controller results in attaining the desired transient reaction under changing operating points. MATLAB simulation effort shows MPPT controller and a DC to DC Luo converter feeding a battery load is achieved. The laboratory experimental results demonstrate that the new proposed MPPT controller in the photovoltaic generating system is valid.

  11. Issues regarding the usage of MPPT techniques in micro grid systems

    Science.gov (United States)

    Szeidert, I.; Filip, I.; Dragan, F.; Gal, A.

    2018-01-01

    The main objective of the control strategies applied at hybrid micro grid systems (wind/hydro/solar), that function based on maximum power point tracking (MPPT) techniques is to improve the conversion system’s efficiency and to preserve the quality of the generated electrical energy (voltage and power factor). One of the main goals of maximum power point tracking strategy is to achieve the harvesting of the maximal possible energy within a certain time period. In order to implement the control strategies for micro grid, there are typically required specific transducers (sensor for wind speed, optical rotational transducers, etc.). In the technical literature, several variants of the MPPT techniques are presented and particularized at some applications (wind energy conversion systems, solar systems, hydro plants, micro grid hybrid systems). The maximum power point tracking implementations are mainly based on two-level architecture. The lower level controls the main variable and the superior level represents the MPPT control structure. The paper presents micro grid structures developed at Politehnica University Timisoara (PUT) within the frame of a research grant. The paper is focused on the application of MPPT strategies on hybrid micro grid systems. There are presented several structures and control strategies and are highlighted their advantages and disadvantages, together with practical implementation guidelines.

  12. Comparative Study of Algorithms (MPPT) Applied to Photovoltaic Systems

    OpenAIRE

    DRIS, MIDA; DJILANI, BEN ATTOUS; DJILANI, Benattous

    2016-01-01

    This work presents a theoretical study of maximum power point tracking (MPPT) for photovoltaic (PV) system. The study includes discussion of three MPPT algorithms (the Perturbation and Observation, Incremental Conductance and the Fractional open circuit voltage) and perform comparative tests between them using actual irradiance data. First the PV system with resistive load is discussed, the modelling and the simulation of the PV generator, the DC/DC converter and the three MPPT algorithms are...

  13. MPPT Schemes for PV System under Normal and Partial Shading Condition: A Review

    Directory of Open Access Journals (Sweden)

    Malik Sameeullah

    2016-08-01

    Full Text Available The photovoltaic system is one of the renewable energy device, which directly converts solar radiation into electricity. The I-V characteristics of PV system are nonlinear in nature and under variable Irradiance and temperature, PV system has a single operating point where the power output is maximum, known as Maximum Power Point (MPP and the point varies on changes in atmospheric conditions and electrical load. Maximum Power Point Tracker (MPPT is used to track MPP of solar PV system for maximum efficiency operation. The various MPPT techniques together with implementation are reported in literature. In order to choose the best technique based upon the requirements, comprehensive and comparative study should be available. The aim of this paper is to present a comprehensive review of various MPPT techniques for uniform insolation and partial shading conditions. Furthermore, the comparison of practically accepted and widely used techniques has been made based on features, such as control strategy, type of circuitry, number of control variables and cost. This review work provides a quick analysis and design help for PV systems. Article History: Received March 14, 2016; Received in revised form June 26th 2016; Accepted July 1st 2016; Available online How to Cite This Article: Sameeullah, M. and Swarup, A. (2016. MPPT Schemes for PV System under Normal and Partial Shading Condition: A Review. Int. Journal of Renewable Energy Development, 5(2, 79-94. http://dx.doi.org/10.14710/ijred.5.2.79-94 

  14. A High-Performance Adaptive Incremental Conductance MPPT Algorithm for Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    Chendi Li

    2016-04-01

    Full Text Available The output characteristics of photovoltaic (PV arrays vary with the change of environment, and maximum power point (MPP tracking (MPPT techniques are thus employed to extract the peak power from PV arrays. Based on the analysis of existing MPPT methods, a novel incremental conductance (INC MPPT algorithm is proposed with an adaptive variable step size. The proposed algorithm automatically regulates the step size to track the MPP through a step size adjustment coefficient, and a user predefined constant is unnecessary for the convergence of the MPPT method, thus simplifying the design of the PV system. A tuning method of initial step sizes is also presented, which is derived from the approximate linear relationship between the open-circuit voltage and MPP voltage. Compared with the conventional INC method, the proposed method can achieve faster dynamic response and better steady state performance simultaneously under the conditions of extreme irradiance changes. A Matlab/Simulink model and a 5 kW PV system prototype controlled by a digital signal controller (TMS320F28035 were established. Simulations and experimental results further validate the effectiveness of the proposed method.

  15. AN EVALUATION OF PHOTOVOLTAIC SYSTEMS MPPT TECHNIQUES UNDER THE CHARACTERISTICS OF OPERATIONAL CONDITIONS

    Directory of Open Access Journals (Sweden)

    I. A. Elzein

    2017-01-01

    Full Text Available In this article an extended literature surveying review is launched on a set of comparative studies of maximum power point tracking (MPPT techniques. Different MPPT methods are addressed with an ultimate aim of how to be maximizing the PV system output power by tracking Pmax in a set of different operational circumstances. In this paper maximum power point tracking, MPPT techniques are reviewed on basis of different parameters related to the design simplicity and/or complexity, implementation, hardware required, and other related aspects.he technology of solar systems has been booming for a while due to its ability to replace current fossil fuels like coal and gas for generation of electricity that produce air, water, and land pollution. In addition it decreased the issue of global warming and climate changes substantially due to being produced in a clean environmental manner and was proved to be an Eco-friendly resource of energy. The photovoltaic systems’ manufacturing process has been improving continuously over the last decade and photovoltaic systems have become an interesting solution. Precisely, PV systems are constituted from arrays of photovoltaic cells, choppers (mainly buck-boost or boost DC/DC converter, MPPT control systems and storage devices and/or grid connections. To improve the efficiency of such systems, various studies have been performed. The demand of PV generation systems seems to be increased for both standalone and grid-connected modes of PV systems. Therefore, an efficient maximum power point tracking (MPPT technique is necessary to initialize the process of tracking the maximum power point MPP at all environmental conditions and then force the PV system to operate at that MPP point.

  16. A Study on the Fuzzy-Logic-Based Solar Power MPPT Algorithms Using Different Fuzzy Input Variables

    Directory of Open Access Journals (Sweden)

    Jaw-Kuen Shiau

    2015-04-01

    Full Text Available Maximum power point tracking (MPPT is one of the key functions of the solar power management system in solar energy deployment. This paper investigates the design of fuzzy-logic-based solar power MPPT algorithms using different fuzzy input variables. Six fuzzy MPPT algorithms, based on different input variables, were considered in this study, namely (i slope (of solar power-versus-solar voltage and changes of the slope; (ii slope and variation of the power; (iii variation of power and variation of voltage; (iv variation of power and variation of current; (v sum of conductance and increment of the conductance; and (vi sum of angles of arctangent of the conductance and arctangent of increment of the conductance. Algorithms (i–(iv have two input variables each while algorithms (v and (vi use a single input variable. The fuzzy logic MPPT function is deployed using a buck-boost power converter. This paper presents the details of the determinations, considerations of the fuzzy rules, as well as advantages and disadvantages of each MPPT algorithm based upon photovoltaic (PV cell properties. The range of the input variable of Algorithm (vi is finite and the maximum power point condition is well defined in steady condition and, therefore, it can be used for multipurpose controller design. Computer simulations are conducted to verify the design.

  17. Simulation and experimental design of a new advanced variable step size Incremental Conductance MPPT algorithm for PV systems.

    Science.gov (United States)

    Loukriz, Abdelhamid; Haddadi, Mourad; Messalti, Sabir

    2016-05-01

    Improvement of the efficiency of photovoltaic system based on new maximum power point tracking (MPPT) algorithms is the most promising solution due to its low cost and its easy implementation without equipment updating. Many MPPT methods with fixed step size have been developed. However, when atmospheric conditions change rapidly , the performance of conventional algorithms is reduced. In this paper, a new variable step size Incremental Conductance IC MPPT algorithm has been proposed. Modeling and simulation of different operational conditions of conventional Incremental Conductance IC and proposed methods are presented. The proposed method was developed and tested successfully on a photovoltaic system based on Flyback converter and control circuit using dsPIC30F4011. Both, simulation and experimental design are provided in several aspects. A comparative study between the proposed variable step size and fixed step size IC MPPT method under similar operating conditions is presented. The obtained results demonstrate the efficiency of the proposed MPPT algorithm in terms of speed in MPP tracking and accuracy. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  18. MPPT algorithm test on a photovoltaic emulating system constructed by a DC power supply and an indoor solar panel

    International Nuclear Information System (INIS)

    Zhou, Z.; Holland, P.M.; Igic, P.

    2014-01-01

    Highlights: • A novel PV emulator is constructed by using conventional solar panels with a DC power supply. • The proposed PV emulator is cost-effectiveness, relatively easy implementation. • The proposed PV emulator avoids the bandwidth problem associated with electronics PV emulators. • Indoor testing of MPPT algorithms and power converters avoids the dependency on solar irradiation. • The PV emulating system has been used for testing a P and O MPPT algorithm and a boost dc converter. - Abstract: In this paper a novel photovoltaic (PV) emulating scheme for testing maximum power point tracking (MPPT) algorithms and PV inverters has been proposed. It is constructed by the parallel connection of conventional solar panels with a DC power supply operating in current source mode. The advantages of the proposed scheme are cost-effectiveness, relatively easy implementation and indoor testing of MPPT algorithms and power converters avoiding weather and time of day dependency on solar irradiation levels. Furthermore, the proposed PV emulator avoids the bandwidth problem associated with the dc converter based PV emulating systems. Detailed circuit connection, parameters, electrical characteristics and mathematical model of the PV emulator are presented and discussed. Proposed PV emulating system has been used to test a boost DC/DC converter controlled by Perturb and Observe (P and O) MPPT algorithm. Test results confirmed the effectiveness of the proposed PV emulation system and all achieved results correspond well to the original designed values

  19. The VSAS approach gives the Best MPPT for Solar Energy Sources

    Directory of Open Access Journals (Sweden)

    Nacer Kouider Msirdi

    2015-08-01

    Full Text Available More and more MPPT (Maximum Power Point Tracking algorithms are in competition to maximize energy extracted from PV systems. This paper shows how to get the best algorithm (the most simple, fast and robust. VSAS (VariableStructure Automatic Systems control methodology is applied to develop the control algorithm, to clarify the rationale behind and get the best optimization algorithm.

  20. Performance analysis of ‘Perturb and Observe’ and ‘Incremental Conductance’ MPPT algorithms for PV system

    Science.gov (United States)

    Lodhi, Ehtisham; Lodhi, Zeeshan; Noman Shafqat, Rana; Chen, Fieda

    2017-07-01

    Photovoltaic (PV) system usually employed The Maximum power point tracking (MPPT) techniques for increasing its efficiency. The performance of the PV system perhaps boosts by controlling at its apex point of power, in this way maximal power can be given to load. The proficiency of a PV system usually depends upon irradiance, temperature and array architecture. PV array shows a non-linear style for V-I curve and maximal power point on V-P curve also varies with changing environmental conditions. MPPT methods grantees that a PV module is regulated at reference voltage and to produce entire usage of the maximal output power. This paper gives analysis between two widely employed Perturb and Observe (P&O) and Incremental Conductance (INC) MPPT techniques. Their performance is evaluated and compared through theoretical analysis and digital simulation on the basis of response time and efficiency under varying irradiance and temperature condition using Matlab/Simulink.

  1. An Experimental Comparison of Two Methods Of Teaching Numerical Control Manual Programming Concepts; Visual Media Versus Hands-On Equipment.

    Science.gov (United States)

    Biekert, Russell

    Accompanying the rapid changes in technology has been a greater dependence on automation and numerical control, which has resulted in the need to find ways of preparing programers for industrial machines using numerical control. To compare the hands-on equipment method and a visual media method of teaching numerical control, an experimental and a…

  2. Adaptive smart simulator for characterization and MPPT construction of PV array

    Science.gov (United States)

    Ouada, Mehdi; Meridjet, Mohamed Salah; Dib, Djalel

    2016-07-01

    Partial shading conditions are among the most important problems in large photovoltaic array. Many works of literature are interested in modeling, control and optimization of photovoltaic conversion of solar energy under partial shading conditions, The aim of this study is to build a software simulator similar to hard simulator and to produce a shading pattern of the proposed photovoltaic array in order to use the delivered information to obtain an optimal configuration of the PV array and construct MPPT algorithm. Graphical user interfaces (Matlab GUI) are built using a developed script, this tool is easy to use, simple, and has a rapid of responsiveness, the simulator supports large array simulations that can be interfaced with MPPT and power electronic converters.

  3. Optimized MPPT algorithm for boost converters taking into account the environmental variables

    Science.gov (United States)

    Petit, Pierre; Sawicki, Jean-Paul; Saint-Eve, Frédéric; Maufay, Fabrice; Aillerie, Michel

    2016-07-01

    This paper presents a study on the specific behavior of the Boost DC-DC converters generally used for powering conversion of PV panels connected to a HVDC (High Voltage Direct Current) Bus. It follows some works pointing out that converter MPPT (Maximum Power Point Tracker) is severely perturbed by output voltage variations due to physical dependency of parameters as the input voltage, the output voltage and the duty cycle of the PWM switching control of the MPPT. As a direct consequence many converters connected together on a same load perturb each other because of the output voltage variations induced by fluctuations on the HVDC bus essentially due to a not insignificant bus impedance. In this paper we show that it is possible to include an internal computed variable in charge to compensate local and external variations to take into account the environment variables.

  4. Adaptive smart simulator for characterization and MPPT construction of PV array

    Energy Technology Data Exchange (ETDEWEB)

    Ouada, Mehdi, E-mail: mehdi.ouada@univ-annaba.org; Meridjet, Mohamed Salah [Electromechanical engineering department, Electromechanical engineering laboratory, Badji Mokhtar University, B.P. 12, Annaba (Algeria); Dib, Djalel [Department of Electrical Engineering, University of Tebessa, Tebessa (Algeria)

    2016-07-25

    Partial shading conditions are among the most important problems in large photovoltaic array. Many works of literature are interested in modeling, control and optimization of photovoltaic conversion of solar energy under partial shading conditions, The aim of this study is to build a software simulator similar to hard simulator and to produce a shading pattern of the proposed photovoltaic array in order to use the delivered information to obtain an optimal configuration of the PV array and construct MPPT algorithm. Graphical user interfaces (Matlab GUI) are built using a developed script, this tool is easy to use, simple, and has a rapid of responsiveness, the simulator supports large array simulations that can be interfaced with MPPT and power electronic converters.

  5. Grid Connected Solar PV System with SEPIC Converter Compared with Parallel Boost Converter Based MPPT

    Directory of Open Access Journals (Sweden)

    T. Ajith Bosco Raj

    2014-01-01

    Full Text Available The main objective of this work is to study the behaviour of the solar PV systems and model the efficient Grid-connected solar power system. The DC-DC MPPT circuit using chaotic pulse width modulation has been designed to track maximum power from solar PV module. The conversion efficiency of the proposed MPPT system is increased when CPWM is used as a control scheme. This paper also proposes a simplified multilevel (seven level inverter for a grid-connected photovoltaic system. The primary goal of these systems is to increase the energy injected to the grid by keeping track of the maximum power point of the panel, by reducing the switching frequency, and by providing high reliability. The maximum power has been tracked experimentally. It is compared with parallel boost converter. Also this model is based on mathematical equations and is described through an equivalent circuit including a PV source with MPPT, a diode, a series resistor, a shunt resistor, and dual boost converter with active snubber circuit. This model can extract PV power and boost by using dual boost converter with active snubber. By using this method the overall system efficiency is improved thereby reducing the switching losses and cost.

  6. An adaptive scale factor based MPPT algorithm for changing solar irradiation levels in outer space

    Science.gov (United States)

    Kwan, Trevor Hocksun; Wu, Xiaofeng

    2017-03-01

    Maximum power point tracking (MPPT) techniques are popularly used for maximizing the output of solar panels by continuously tracking the maximum power point (MPP) of their P-V curves, which depend both on the panel temperature and the input insolation. Various MPPT algorithms have been studied in literature, including perturb and observe (P&O), hill climbing, incremental conductance, fuzzy logic control and neural networks. This paper presents an algorithm which improves the MPP tracking performance by adaptively scaling the DC-DC converter duty cycle. The principle of the proposed algorithm is to detect the oscillation by checking the sign (ie. direction) of the duty cycle perturbation between the current and previous time steps. If there is a difference in the signs then it is clear an oscillation is present and the DC-DC converter duty cycle perturbation is subsequently scaled down by a constant factor. By repeating this process, the steady state oscillations become negligibly small which subsequently allows for a smooth steady state MPP response. To verify the proposed MPPT algorithm, a simulation involving irradiances levels that are typically encountered in outer space is conducted. Simulation and experimental results prove that the proposed algorithm is fast and stable in comparison to not only the conventional fixed step counterparts, but also to previous variable step size algorithms.

  7. A Two-Level Sensorless MPPT Strategy Using SRF-PLL on a PMSG Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Amina Echchaachouai

    2017-01-01

    Full Text Available In this paper, a two-level sensorless Maximum Power Point Tracking (MPPT strategy is presented for a variable speed Wind Energy Conversion System (WECS. The proposed system is composed of a wind turbine, a direct-drive Permanent Magnet Synchronous Generator (PMSG and a three phase controlled rectifier connected to a DC load. The realised generator output power maximization analysis justifies the use of the Field Oriented Control (FOC giving the six Pulse Width Modulation (PWM signals to the active rectifier. The generator rotor speed and position required by the FOC and the sensorless MPPT are estimated using a Synchronous Reference Frame Phase Locked Loop (SRF-PLL. The MPPT strategy used consists of two levels, the first level is a power regulation loop and the second level is an extremum seeking bloc generating the coefficient gathering the turbine characteristics. Experimental results validated on a hardware test setup using a DSP digital board (dSPACE 1104 are presented. Figures illustrating the estimated speed and angle confirm that the SRF-PLL is able to give an estimated speed and angle which closely follow the real ones. Also, the power at the DC load and the power at the generator output indicate that the MPPT gives optimum extracted power. Finally, other results show the effectiveness of the adopted approach in real time applications.

  8. A randomised controlled trial comparing two methods of teaching medical students trauma and orthopaedics: traditional lectures versus the "donut round".

    Science.gov (United States)

    Bulstrode, C; Gallagher, F A; Pilling, E L; Furniss, D; Proctor, R D

    2003-04-01

    To assess whether a new form of teaching, the 'donut round', is as good at imparting factual knowledge as interactive lectures in both the short-term and the long-term. Randomised controlled trial. University of Oxford Medical School. 106 fifth year clinical medical students taught half of their A&E/trauma course by donut round and half by lecture. The results of multiple choice questions (MCQs) divided according to how the material was taught. Three MCQ papers were set: one at the end of a four-week course, one approximately 10 weeks later and a final exam approximately 17 months after the first. At the first MCQ, the average result for questions taught by donut round was 41.0 (out of 50) and for those taught by conventional lecture was 40.1. At 10 weeks these averages fell to 36.3 and 37.3 and at 17 months they were 38.7 and 38.1, respectively. None of these pairs were significantly different. Ratios were calculated for each candidate by dividing their donut round score by their lecture score. The average ratios for the first, second and third MCQ papers were: 1.029, 1.007 and 1.027, respectively, and were not significantly different. The individual ratios of all candidates in all three MCQs were plotted against their equivalent total mark. The calculated linear regression showed a statistically significant advantage of donut rounds over lectures in those candidates who scored a total mark less than 89 (n=260, p=0.02). Donut rounds are at least as good as lectures in imparting factual knowledge and may provide a selective advantage to weaker students.

  9. Comparison of two methods of dental prophylaxis: evaluation of arterial pressure and patient comfort in a clinical randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Camila Lopes FERREIRA

    Full Text Available Abstract Introduction The number of hypertensive patients is increasing and prophylaxis with bicarbonate jet are widely performed in clinical practice using large amounts of this substance in a short period of time, which may lead to increased arterial pressure. In the literature there are several studies that analyze the effect of sodium bicarbonate jet on the biofilm and dental structures, but not report the effect on arterial pressure. Aim Evaluated the change in arterial pressure before and after two procedures of dental prophylaxis, jet baking soda application and conventional prophylaxis, and patient opinion of the comfort of each system was obtained. Material and method We selected 20 patients aged 18 to 30 in need of prophylaxis to remove biofilm. The patients were placed into three different treatment groups: sodium bicarbonate jet (G1, conventional prophylaxis (G2 and control (G3, with a one month interval between treatments. Patients were divided into groups randomly. Measurements were performed immediately before and after the procedure, 15 and 30 minutes after the end of treatment. Patient comfort was measured using a Visual Analog Scale (VAS at the end of each treatment. Data were analyzed by analysis of variance. Result There was a statistically significant difference in the comfort of the procedures, with G2 and G3 being better than G1. Additionally, an increase in the diastolic blood pressure was observed in sodium bicarbonate jet group evaluated just after the procedure. Conclusion The conventional prophylaxis is more comfortable from the patient stand point and does not alter arterial pressure.

  10. Computer tablet or telephone? A randomised controlled trial exploring two methods of collecting data from drug and alcohol outpatients.

    Science.gov (United States)

    Hobden, Breanne; Bryant, Jamie; Carey, Mariko; Sanson-Fisher, Rob; Oldmeadow, Christopher

    2017-08-01

    Both computerised and telephone surveys have potential advantages for research data collection. The current study aimed to determine the: (i) feasibility, (ii) acceptability, and (iii) cost per completed survey of computer tablet versus telephone data collection for clients attending an outpatient drug and alcohol treatment clinic. Two-arm randomised controlled trial. Clients attending a drug and alcohol outpatient clinic in New South Wales, Australia, were randomised to complete a baseline survey via computer tablet in the clinic or via telephone interview within two weeks of their appointment. All participants completed a three-month follow-up survey via telephone. Consent and completion rates for the baseline survey were significantly higher in the computer tablet condition. The time taken to complete the computer tablet survey was lower (11min) than the telephone condition (17min). There were no differences in the proportion of consenters or completed follow-up surveys between the two conditions at the 3-month follow-up. Acceptability was high across both modes of data collection. The cost of the computer tablet condition was $67.52 greater per completed survey than the telephone condition. There is a trade-off between computer tablet and telephone data collection. While both data collection methods were acceptable to participants, the computer tablet condition resulted in higher consent and completion rates at baseline, therefore yielding greater external validity, and was quicker for participants to complete. Telephone data collection was however, more cost-effective. Researchers should carefully consider the mode of data collection that suits individual study needs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Comparison of Two Methods: Spinal Anesthesia and Ischiorectal Block on Post Hemorrhoidectomy Pain and Hospital Stay: A Randomized Control Trial.

    Science.gov (United States)

    Nadri, Sedigheh; Mahmoudvand, Hormoz; Rokrok, Shirin; Tarrahi, Mohammad Javad

    2017-11-27

    Hemorrhoidectomy is one of the most common hemorrhoid surgery. Many areas are innervated by nerves, and this makes the surgery to be very painful. Various anesthetic methods have been proposed, and the number of investigations and procedures demonstrated the absence of a reliable method for reducing pain. This study compares the cavity ischiorectal block with spinal anesthesia in reducing postoperative pain, analgesic consumption, and hospital stay. This study is a randomized control trial carried out on seventy patients sampled. Thirty-five (35) among them were placed in spinal anesthesia group, and the other 35 were placed in the ischiorectal block group. According to the study, questionnaire was designed in such a way that postoperative variables such as postoperative pain, analgesic consumption, changes in blood pressure, heart rate and hospital stay in both groups were evaluated and compared. IRCT2015111616516N3 ( http://en.search.irct.ir/search?query=IRCT2015111616516N3 ) Results: In this study, the pain scores on Visual Analogue Scale (VAS) at 0, 6, 12, and 24 hr for spinal anesthesia group after surgery were 0, 3.08 ± 0.78, 2.05 ± 1.02, 1.11 ± 0.83, respectively (p blocks were 0.98 ± 0.25, 1.57 ± 0.81, 0.91 ± 0.91, and 0.63 ± 0.31 respectively, which indicated lesser pain after surgery in the ischiorectal block at 6, 12, and 24 hr. In this study, out of the 35 patients that underwent spinal anesthesia, 28 patients (80%) were hospitalized in the first 6 hr, 13 patients (37.1%) in the second 6 hr, 3 patients (8.6%) in the second 12 hr after surgery. For patients under the ischiorectal block, the number of patients hospitalized were 13 patients (37.1%), in the first 6 hr, 4 patients (11.4%) in the second 6 hr, and 1 (2.9%) were hospitalized in the second 12 hr after surgery (p blocks causes less pain, require fewer painkillers, and reduces the hospital stay after surgery than spinal anesthesia.

  12. Boost-Based MPPT for the MTM PCDU of the BepiColombo Mission

    Science.gov (United States)

    Lapena, E.; Rueda, P.; Garcia, O.; Cobos, J. A.; Alou, P.; Oliver, J.; del Nuevo, M. A.; de las Mulas, E. M.; Soto, A.; Rancano, J.

    2008-09-01

    BepiColombo is an ESA mission to Mercury to be launched in 2013. A better knowledge of the origin and evolution of the planet, of its structure and vestigial atmosphere, of its magnetosphere, and of the origin of its magnetic field are the main objectives for the program. The journey to Mercury will last for approximately 6 years, and will be based on the gravity of the Earth, Venus and Mercury, and on the use of Solar Electric Propulsion. For the last, the use of the MPPT concept is essential for the mission.A mission power demand of up to 14kW is foreseen in the cruise phase for the Mercury Transfer Module (MTM) PCDU, being the power subsystem based on a 100V bus. Under this scenario, the use of a classical step-down regulator for the implementation of the MPPT power cell would require to keep the worst case minimum solar array voltage over the bus for any mission operating condition. Then, the maximum solar array voltage would become as high as to overpass the insulating capability of the isolation layer between the solar array cells and the substrate, under the high temperature environment experienced by the spacecraft near Mercury.As a result, the development of a step-up MPPT Array Power Regulator (APR) becomes a critical issue for the mission feasibility. Moreover, due to the hard environment that the solar array will be exposed to, the segregation of the solar array power is a very desirable feature. Furthermore, apart from the two classical operating modes of the APR - conductance or MPPT, depending on the spacecraft user loads demand and the available solar array power - the APR will have to operate in S3R mode for solar array voltages over the bus, with a fully autonomous transition between the three operating modes.This paper covers all the aspects related with the design of the APR MPPT concept and its implementation: APR power cell topology, control scheme, control strategy, protections. The implications on the design of the MTM PCDU MEA will be also

  13. Design and simulation of maximum power point tracking (MPPT) system on solar module system using constant voltage (CV) method

    Science.gov (United States)

    Bhatara, Sevty Satria; Iskandar, Reza Fauzi; Kirom, M. Ramdlan

    2016-02-01

    Solar energy is one of renewable energy resource where needs a photovoltaic module to convert it into electrical energy. One of the problems on solar energy conversion is the process of battery charging. To improve efficiency of energy conversion, PV system needs another control method on battery charging called maximum power point tracking (MPPT). This paper report the study on charging optimation using constant voltage (CV) method. This method has a function of determining output voltage of the PV system on maximal condition, so PV system will always produce a maximal energy. A model represented a PV system with and without MPPT was developed using Simulink. PV system simulation showed a different outcome energy when different solar radiation and numbers of solar module were applied in the model. On the simulation of solar radiation 1000 W/m2, PV system with MPPT produces 252.66 Watt energy and PV system without MPPT produces 252.66 Watt energy. The larger the solar radiation, the greater the energy of PV modules was produced.

  14. A Single Phase Doubly Grounded Semi-Z-Source Inverter for Photovoltaic (PV Systems with Maximum Power Point Tracking (MPPT

    Directory of Open Access Journals (Sweden)

    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.

  15. Optimized MPPT-based converter for TEG energy harvester to power wireless sensor and monitoring system in nuclear power plant

    Science.gov (United States)

    Xing, Shaoxu; Anakok, Isil; Zuo, Lei

    2017-04-01

    Accidents like Fukushima Disasters push people to improve the monitoring systems for the nuclear power plants. Thus, various types of energy harvesters are designed to power these systems and the Thermoelectric Generator (TEG) energy harvester is one of them. In order to enhance the amount of harvested power and the system efficiency, the power management stage needs to be carefully designed. In this paper, a power converter with optimized Maximum Power Point Tracking (MPPT) is proposed for the TEG Energy Harvester to power the wireless sensor network in nuclear power plant. The TEG Energy Harvester is installed on the coolant pipe of the nuclear plant and harvests energy from its heat energy while the power converter with optimized MPPT can make the TEG Energy Harvester output the maximum power, quickly response to the voltage change and provide sufficient energy for wireless sensor system to monitor the operation of the nuclear power plant. Due to the special characteristics of the Single-Ended Primary Inductor Converter (SEPIC) when it is working in the Discontinuous Inductor Current Mode (DICM) and Continuous Conduction Mode (CCM), the MPPT method presented in this paper would be able to control the converter to achieve the maximum output power in any working conditions of the TEG system with a simple circuit. The optimized MPPT algorithm will significantly reduce the cost and simplify the system as well as achieve a good performance. Experiment test results have shown that, comparing to a fixed- duty-cycle SEPIC which is specifically designed for the working on the secondary coolant loop in nuclear power plant, the optimized MPPT algorithm increased the output power by 55%.

  16. Power converter with maximum power point tracking MPPT for small wind-electric pumping systems

    International Nuclear Information System (INIS)

    Lara, David; Merino, Gabriel; Salazar, Lautaro

    2015-01-01

    Highlights: • We implement a wind electric pumping system of small power. • The power converter allowed to change the operating point of the electro pump. • Two control techniques were implemented in the power converter. • The control V/f variable allowed to increase the power generated by the permanent magnet generator. - Abstract: In this work, an AC–DC–AC direct-drive power converter was implemented for a wind electric pumping system consisting of a permanent magnet generator (PMG) of 1.3 kW and a peripheral single phase pump of 0.74 kW. In addition, the inverter linear V/f control scheme and the maximum power point tracking (MPPT) algorithm with variable V/f were developed. MPPT algorithm seeks to extract water in a wide range of power input using the maximum amount of wind power available. Experimental trials at different pump pressures were conducted. With a MPPT tracking system with variable V/f, a power value of 1.3 kW was obtained at a speed of 350 rpm and a maximum operating hydraulic head of 50 m. At lower operating heads pressures (between 10 and 40 m), variable V/f control increases the power generated by the PMG compared to the linear V/f control. This increase ranged between 4% and 23% depending on the operating pressure, with an average of 13%, getting close to the maximum electrical power curve of the PMG. The pump was driven at variable frequency reaching a minimum speed of 0.5 times the rated speed. Efficiency of the power converter ranges between 70% and 95% with a power factor between 0.4 and 0.85, depending on the operating pressure

  17. Boost-Based MPPT Converter Topology Trade-Off for Space Applications

    Science.gov (United States)

    Garcia, O.; Alou, P.; Oliver, J. A.; Diaz, D.; Meneses, D.; Cobos, J. A.; Soto, A.; Lapena, E.; Rancano, J.

    2008-09-01

    High power and high voltage - 100V - power buses are often required not only in the frame of the telecommunication spacecrafts, but also for those scientific and interplanetary mission cases where a high user power load demand is driving the design of the power subsystem. On many cases, the use of Maximum Power Point Tracking (MPPT) is essential for an optimum power subsystem sizing.The adaptation to 100V of the existing MPPT concepts for 28V buses - like GOCE, ROSETTA, etc. - is not immediate, as happens in general terms with the upgrading of Power Conditioning Units from 28V to 50V and 100V. Moreover, for those cases where the solar array voltage is under the bus voltage, a step-up boost power cell is mandatory for the MPPT implementation.This paper will focus on the definition of the main performance characteristics that must have a converter power cell to fit the above mentioned application range. Starting with the establishment of the relevant trade-off parameters, in terms of power handling capability, input and output operational voltage ranges (both in nominal and emergency conditions), conducted emissions, bus capacitor and solar array output impedance considerations, several candidate topologies are analysed: conventional boost, interleaved DCM and CCM boost, two inductor boost, boost with ripple cancellation and boost with switch near ground. Some critical aspects like mass, efficiency and number of reactive and power switching elements are also covered.Special attention is paid to the feasibility of the design for the control loop that will govern the converter operation when forming part of a PCU, taking into account the effects of the RHPZ inherent to most of the boost converter topologies. Some of the candidate topologies where prototyped to demonstrate in the laboratory the performances identified during the analysis phase.

  18. DSPACE Real-Time Implementation of MPPT-Based FLC Method

    Directory of Open Access Journals (Sweden)

    Abdullah M. Noman

    2013-01-01

    Full Text Available Maximum power point trackers are so important in photovoltaic systems to improve their overall efficiency. This paper presents a photovoltaic system with maximum power point tracking facility. An intelligent fuzzy logic controller method is proposed in this paper to achieve the maximum power point tracking of PV modules. The system consists of a photovoltaic solar module connected to a DC-DC buck-boost converter. The system is modeled using MATLAB/SIMULINK. The system has been experienced under disturbance in the photovoltaic temperature and irradiation levels. The simulation results show that the proposed maximum power tracker tracks the maximum power accurately and successfully in all conditions tested. The MPPT system is then experimentally implemented. DSPACE is used in the implementation of the MPPT hardware setup for real-time control. Data acquisition and control system is implemented using dSPACE 1104 software and digital signal processor card. The simulation and practical results show that the proposed system tracked the maximum power accurately and successfully under all atmospheric conditions.

  19. Modeling, analysis and comparison of TSR and OTC methods for MPPT and power smoothing in permanent magnet synchronous generator-based wind turbines

    International Nuclear Information System (INIS)

    Nasiri, M.; Milimonfared, J.; Fathi, S.H.

    2014-01-01

    Highlights: • Small signal modeling of PMSG wind turbine with two controllers are introduced. • Poles and zeroes analyzing of OTC and TSR methods is performed. • Generator output power with varying wind speed in PMSG wind turbine is studied. • MPPT capability of OTC and TSR methods to wind speed variations are compared. • Power smoothing capability and reducing mechanical stress of both methods are studied. - Abstract: This paper presents a small signal modeling of a direct-driven permanent magnet synchronous generator (PMSG) based on wind turbine which is connected to the grid via back-to-back converters. The proposed small signal model includes two maximum power point tracking (MPPT) controllers: tip speed ratio (TSR) control and optimal torque control (OTC). These methods are analytically compared to illustrate MPPT and power smoothing capability. Then, to compare the MPPT and power smoothing operation of the mentioned methods, simulations are performed in MATLAB/Simulink software. From the simulation results, OTC is highly efficient in power smoothing enhancement and has clearly good performance to extract maximum power from wind; however, TSR control has definitely fast responses to wind speed variations with the expense of higher fluctuations due to its non-minimum phase characteristic

  20. Variable frequency iteration MPPT for resonant power converters

    Science.gov (United States)

    Zhang, Qian; Bataresh, Issa; Chen, Lin

    2015-06-30

    A method of maximum power point tracking (MPPT) uses an MPPT algorithm to determine a switching frequency for a resonant power converter, including initializing by setting an initial boundary frequency range that is divided into initial frequency sub-ranges bounded by initial frequencies including an initial center frequency and first and second initial bounding frequencies. A first iteration includes measuring initial powers at the initial frequencies to determine a maximum power initial frequency that is used to set a first reduced frequency search range centered or bounded by the maximum power initial frequency including at least a first additional bounding frequency. A second iteration includes calculating first and second center frequencies by averaging adjacent frequent values in the first reduced frequency search range and measuring second power values at the first and second center frequencies. The switching frequency is determined from measured power values including the second power values.

  1. Study of a photovoltaic system with MPPT using Matlab

    Directory of Open Access Journals (Sweden)

    Dumitru Pop

    2012-12-01

    Full Text Available In this paper a photovoltaic (PV system is analyzed using Matlab. First, a Matlab code is written in order to obtain the I-V and P-V curves at different values of solar irradiation and cell temperature. The results were compared with the experimental data of a commercial PV module, USP 150. Then, the code was implemented in Simulink and, along with a MPPT algorithm and a DC-DC converter, the whole system was simulated.

  2. MPPT Technique Based on Current and Temperature Measurements

    OpenAIRE

    Vicente, Eduardo Moreira; Moreno, Robson Luiz; Ribeiro, Enio Roberto

    2015-01-01

    This paper presents a new maximum power point tracking (MPPT) method based on the measurement of temperature and short-circuit current, in a simple and efficient approach. These measurements, which can precisely define the maximum power point (MPP), have not been used together in other existing techniques. The temperature is measured with a low cost sensor and the solar irradiance is estimated through the relationship of the measured short-circuit current and its reference. Fast tracking spee...

  3. A High-Performance Adaptive Incremental Conductance MPPT Algorithm for Photovoltaic Systems

    OpenAIRE

    Chendi Li; Yuanrui Chen; Dongbao Zhou; Junfeng Liu; Jun Zeng

    2016-01-01

    The output characteristics of photovoltaic (PV) arrays vary with the change of environment, and maximum power point (MPP) tracking (MPPT) techniques are thus employed to extract the peak power from PV arrays. Based on the analysis of existing MPPT methods, a novel incremental conductance (INC) MPPT algorithm is proposed with an adaptive variable step size. The proposed algorithm automatically regulates the step size to track the MPP through a step size adjustment coefficient, and a user prede...

  4. Accurate Simulation of MPPT Methods Performance When Applied to Commercial Photovoltaic Panels

    OpenAIRE

    Cubas, Javier; Pindado, Santiago; Sanz-Andrés, Ángel

    2015-01-01

    A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers' datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature) and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commer...

  5. An Improved MPPT Algorithm for PV Generation Applications Based on P-U Curve Reconstitution

    OpenAIRE

    Wang, Yaoqiang; Zhang, Meiling; Cheng, Xian

    2016-01-01

    The output power of PV array changes with the variation of environmental factors, such as temperature and solar irradiation. Therefore, a maximum power point (MPP) tracking (MPPT) algorithm is essential for the photovoltaic generation system. However, the P-U curve changes dynamically with the variation of the environmental factors; here, the misjudgment may occur if a simple perturb-and-observe (P&O) MPPT algorithm is used. In order to solve this problem, this paper takes MPPT as the main re...

  6. MPPT Menggunakan Metode Hibrid JST Dan Algoritma Genetika Untuk Sistem Photovoltaic

    OpenAIRE

    Wibisono, Gunawan; Pramono, Sholeh Hadi; Muslim, Muhammad Aziz

    2014-01-01

    Maximum Power Point Tracking is a method to track power point of an energy source in order to generate maximum power. One of the MPPT method for photovoltaic system is fractional open voltage MPPT. In this paper the fractional open voltage MPPT is modified by using artificial neural network trained using genetic algorithm. Artificial neural networks are successfully trained by using genetic algorithm. The best mean squared error (MSE) value obtained is 0.000453. The network tested using tes...

  7. Real-Time Genetic Algorithms-Based MPPT: Study and Comparison (Theoretical an Experimental with Conventional Methods

    Directory of Open Access Journals (Sweden)

    Slimane Hadji

    2018-02-01

    Full Text Available Maximum Power Point Tracking (MPPT methods are used in photovoltaic (PV systems to continually maximize the PV array output power, which strongly depends on both solar radiation and cell temperature. The PV power oscillations around the maximum power point (MPP resulting from the conventional methods and complexity of the non-conventional ones are convincing reasons to look for novel MPPT methods. This paper deals with simple Genetic Algorithms (GAs based MPPT method in order to improve the convergence, rapidity, and accuracy of the PV system. The proposed method can also efficiently track the global MPP, which is very useful for partial shading. At first, a review of the algorithm is given, followed with many test examples; then, a comparison by means Matlab/Simulink© (R2009b is conducted between the proposed MPPT and, the popular Perturb and Observe (PO and Incremental Conductance (IC techniques. The results show clearly the superiority of the proposed controller. Indeed, with the proposed algorithm, oscillations around the MPP are dramatically minimized, a better stability is observed and increase in the output power efficiency is obtained. All these results are experimentally validated by a test bench developed at LIAS laboratory (Poitiers University, Poitiers, France using real PV panels and a PV emulator which allows one to define a profile insolation model. In addition, the proposed method permits one to perform the test of linearity between the optimal current I mp (current at maximum power and the short-circuit current I sc , and between the optimal voltage V mp and open-circuit voltage V oc , so the current and voltage factors can be easily obtained with our algorithm.

  8. Lightweight DC-DC Converter with Partial Power Processing and MPPT for a Solar Powered Aircraft

    Science.gov (United States)

    Diab-Marzouk, Ahmad

    A lightweight dc-dc partial power processing converter is demonstrated for solar aerospace applications. A system-level model is conceived to determine conformity to payload and target distance objectives, with the Solarship aircraft used as an application example. The concept of partial power processing is utilized to realize a high efficiency lightweight converter that performs Max Peak Power Tracking (MPPT) to transfer power from the aircraft solar array to the high-voltage battery bus. The isolated Cuk is determined to be a suitable converter topology for the application. A small-signal model is derived for control design. The operation of a 400V, 2.7 kW prototype is verified at high frequency (200 kHz), high efficiency (> 98%), small mass (0.604 kg), and uses no electrolytic capacitors. MPPT operation is verified on a 376 V commercial solar installation at The University of Toronto. The prototype serves as an enabling technology for solar aerospace applications.

  9. A novel MPPT method for enhancing energy conversion efficiency taking power smoothing into account

    International Nuclear Information System (INIS)

    Liu, Jizhen; Meng, Hongmin; Hu, Yang; Lin, Zhongwei; Wang, Wei

    2015-01-01

    Highlights: • We discuss the disadvantages of conventional OTC MPPT method. • We study the relationship between enhancing efficiency and power smoothing. • The conversion efficiency is enhanced and the volatility of power is suppressed. • Small signal analysis is used to verify the effectiveness of proposed method. - Abstract: With the increasing capacity of wind energy conversion system (WECS), the rotational inertia of wind turbine is becoming larger. And the efficiency of energy conversion is significantly reduced by the large inertia. This paper proposes a novel maximum power point tracking (MPPT) method to enhance the efficiency of energy conversion for large-scale wind turbine. Since improving the efficiency may increase the fluctuations of output power, power smoothing is considered as the second control objective. A T-S fuzzy inference system (FIS) is adapted to reduce the fluctuations according to the volatility of wind speed and accelerated rotor speed by regulating the compensation gain. To verify the effectiveness, stability and good dynamic performance of the new method, mechanism analyses, small signal analyses, and simulation studies are carried out based on doubly-fed induction generator (DFIG) wind turbine, respectively. Study results show that both the response speed and the efficiency of proposed method are increased. In addition, the extra fluctuations of output power caused by the high efficiency are reduced effectively by the proposed method with FIS

  10. Dynamic Performance Comparison for MPPT-PV Systems using Hybrid Pspice/Matlab Simulation

    Science.gov (United States)

    Aouchiche, N.; Becherif, M.; HadjArab, A.; Aitcheikh, M. S.; Ramadan, H. S.; Cheknane, A.

    2016-10-01

    The power generated by solar photovoltaic (PV) module depends on the surrounding irradiance and temperature. This paper presents a hybrid Matlab™/Pspice™ simulation model of PV system, combined with Cadence software SLPS. The hybridization is performed in order to gain the advantages of both simulation tools such as accuracy and efficiency in both Pspice electronic circuit and Matlab™ mathematical modelling respectively. For this purpose, the PV panel and the boost converter are developed using Pspice™ and hybridized with the mathematical Matlab™ model of maximum power point method controller (MPPT) through SLPS. The main objective is verify the significance of using the proposed hybrid simulation techniques in comparing the different MPPT algorithms such as the perturbation and observation (P&O), incremental of conductance (Inc-Cond) and counter reaction voltage using pilot cell (Pilot-Cell). Various simulations are performed under different atmospheric conditions in order to evaluate the dynamic behaviour for the system under study in terms of stability, efficiency and rapidity.

  11. Comparison of Different MPPT Algorithms with a Proposed One Using a Power Estimator for Grid Connected PV Systems

    Directory of Open Access Journals (Sweden)

    Manel Hlaili

    2016-01-01

    Full Text Available Photovoltaic (PV energy is one of the most important energy sources since it is clean and inexhaustible. It is important to operate PV energy conversion systems in the maximum power point (MPP to maximize the output energy of PV arrays. An MPPT control is necessary to extract maximum power from the PV arrays. In recent years, a large number of techniques have been proposed for tracking the maximum power point. This paper presents a comparison of different MPPT methods and proposes one which used a power estimator and also analyses their suitability for systems which experience a wide range of operating conditions. The classic analysed methods, the incremental conductance (IncCond, perturbation and observation (P&O, ripple correlation (RC algorithms, are suitable and practical. Simulation results of a single phase NPC grid connected PV system operating with the aforementioned methods are presented to confirm effectiveness of the scheme and algorithms. Simulation results verify the correct operation of the different MPPT and the proposed algorithm.

  12. ¬MPPT Pada Sistem PV Menggunakan Algoritma Firefly dan Modified P&O dengan Konverter Hybrid Cuk terkoneksi ke Grid Satu Phasa di Bawah Kondisi Partial Shaded

    Directory of Open Access Journals (Sweden)

    Dhuhari Chalis Bani

    2017-01-01

    Full Text Available Abstrak— Photovoltaic (PV merupakan sumber energi terbarukan yang paling banyak dijumpai di alam serta merupakn energi alternatif yang sangat pesat perkembangannya. Untuk mengahasilkan daya, sebuah PV dipengaruhi sebuah nilai intensitas cahaya matahari yang mengenainya. Sebuah sistem PV membutuhkan sebuah kontrol yang bertujuan untuk meningkatkan efisien daya PV tersebut. Kontrol ini adalah Maximum Power Point Tracking (MPPT yang dapat mengoptimalkan daya yang dihasilkan oleh PV.  Sebuah PV hanya menghasilkan nilai tegangan yang rendah, untuk itu perlu menggunakan koverter DC-DC step up untuk menaikan rasio tegangan DC tadi. Untuk mengoptimalkan sistem ini, diperlukan sebuah konverter yang efisien dan dapat menghasilkan rasio konversi tegangan yang tinggi. Pada penelitian menggunakan firefly algoritm (FFA dan modified perturb and observe (P&O sebagai MPPT untuk mendapatkan nilai daya optimal pada keluaran PV.  Konverter DC-DC yang digunakan adalah hybrid cuk converter boost mode yang memiliki rasio tegangan yang tinggi. Dari DC-link kemudian masuk ke inverter (VSI yang diinterkoneksi dengan grid menggunakan current control. Hasil analisis simulasi menunjukan bahwa FFA dan P&O mampu menghasilkan daya PV yang optimum dengan riak yang kecil dan konverter hybrid cuk converter boost mode dapat menghasilkan rasio tegangan yang lebih besar dibandingkan konverter cuk biasa.   Kata Kunci — PV, MPPT FFA, MPPT P&O, Hybrid Cuk Converter, DC-Link, Inverter Grid Connected

  13. Comparision of Perturb and Observer and Incremental Conductance MPPT Based Solar Tracking System

    OpenAIRE

    Nilam Rajendra Deshmukh

    2015-01-01

    This paper presents a detailed analysis of the two most well-known hill-climbing maximum power point tracking (MPPT) algorithms: the perturb-and-observe (P&O) and incremental conductance (INC). The purpose of the analysis is to clarify some common misconceptions in the literature regarding these two trackers, therefore helping the selection process of MPPT

  14. MPPT Technique Based on Current and Temperature Measurements

    Directory of Open Access Journals (Sweden)

    Eduardo Moreira Vicente

    2015-01-01

    Full Text Available This paper presents a new maximum power point tracking (MPPT method based on the measurement of temperature and short-circuit current, in a simple and efficient approach. These measurements, which can precisely define the maximum power point (MPP, have not been used together in other existing techniques. The temperature is measured with a low cost sensor and the solar irradiance is estimated through the relationship of the measured short-circuit current and its reference. Fast tracking speed and stable steady-state operation are advantages of this technique, which presents higher performance when compared to other well-known techniques.

  15. Accurate Simulation of MPPT Methods Performance When Applied to Commercial Photovoltaic Panels

    Directory of Open Access Journals (Sweden)

    Javier Cubas

    2015-01-01

    Full Text Available A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers’ datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions.

  16. Accurate simulation of MPPT methods performance when applied to commercial photovoltaic panels.

    Science.gov (United States)

    Cubas, Javier; Pindado, Santiago; Sanz-Andrés, Ángel

    2015-01-01

    A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers' datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature) and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions.

  17. SPICE Modeling and Simulation of a MPPT Algorithm

    Directory of Open Access Journals (Sweden)

    Miona Andrejević Stošović

    2014-06-01

    Full Text Available One among several equally important subsystems of a standalone photovoltaic (PV system is the circuit for maximum power point tracking (MPPT. There are several algorithms that may be used for it. In this paper we choose such an algorithm based on the maximum simplicity criteria. Then we make some small modifications to it in order to make it more robust. We synthesize a circuit built out of elements from the list of elements recognized by SPICE. The inputs are the voltage and the current at the PV panel to DC-DC converter interface. Its task is to generate a pulse width modulated pulse train whose duty ratio is defined to keep the input impedance of the DC-DC converter at the optimal value.

  18. MPPT implementation for the outdoor characterization of CPV modules

    Science.gov (United States)

    Sánchez, Daniel; Mora, Jaime; Calvo-Parra, Gustavo; Martínez, María

    2015-09-01

    One of the challenges during the characterization of CPV modules is to deal with the thermal behavior. During normal operation in the field the concentrator is connected to the inverter and a fraction of the energy coming from the sun is dissipated with the corresponding conversion into electricity. On the other hand, when making the characterization of CPV modules, they are usually kept in VOC between I-V sweeps, what means that none energy is converted into electricity resulting in a higher operation temperature. Current standards, like IEC-62108:2007 and IEC-62670-3 C01 draft, define that, during the outdoor characterization, the CPV module should be connected to an electrical load to maintain it near MPP between I-V sweeps, what simulates normal operating conditions. The easiest solution could be to use mini-inverters, but it is an expensive solution and not easily adaptable to the different technologies. ISFOC has designed and developed a low-cost MPPT equipment that can be easily implemented in an outdoor characterization laboratory. This equipment is compatible with most of the CPV technologies since it covers a wide range of voltage and current values (up to 150V and 10A) and it is able to distinguish between absolute and local MPP what permits working with modules in any phase of development or making shading effects measurements. Currently, the MPPT is implemented and in operation at ISFOC's outdoor laboratory to make the long term validation. But the results obtained up to now are very promising; the equipment is able to maintain the CPV module under test within a ±3% of the expected power in stable conditions and is able to keep tracking the MPP after any variation in the operating conditions, like cloudy periods, tracking incidence, shading, etc.

  19. Maximum Power Point Tracking (MPPT Pada Sistem Pembangkit Listrik Tenaga Angin Menggunakan Buck-Boost Converter

    Directory of Open Access Journals (Sweden)

    Muhamad Otong

    2017-05-01

    Full Text Available In this paper, the implementation of the Maximum Power Point Tracking (MPPT technique is developed using buck-boost converter. Perturb and observe (P&O MPPT algorithm is used to searching maximum power from the wind power plant for charging of the battery. The model used in this study is the Variable Speed Wind Turbine (VSWT with a Permanent Magnet Synchronous Generator (PMSG. Analysis, design, and modeling of wind energy conversion system has done using MATLAB/simulink. The simulation results show that the proposed MPPT produce a higher output power than the system without MPPT. The average efficiency that can be achieved by the proposed system to transfer the maximum power into battery is 90.56%.

  20. Comparison between the Conventional Methods and PSO Based MPPT Algorithm for Photovoltaic Systems

    OpenAIRE

    Ramdan B. A. Koad; Ahmed. F. Zobaa

    2014-01-01

    Since the output characteristics of photovoltaic (PV) system depends on the ambient temperature, solar radiation and load impedance, its maximum power point (MPP) is not constant. Under each condition PV module has a point at which it can produce its MPP. Therefore, a maximum power point tracking (MPPT) method is needed to uphold the PV panel operating at its MPP. This paper presents comparative study between the conventional MPPT methods used in (PV) system: Perturb and Observe (P&O), Increm...

  1. Evaluation of two methods for assessing gene-environment interactions using data from the Danish case-control study of facial clefts

    DEFF Research Database (Denmark)

    Etheredge, Analee J; Christensen, Kaare; Del Junco, Deborah

    2005-01-01

    BACKGROUND: Epidemiological investigations have begun to consider gene-environment (GE) interactions as potential risk factors for many diseases, including several different birth defects. However, traditional methodological approaches for the analysis of case-control data tend to have low power...

  2. Development and Analysis of a Novel Multi-Mode MPPT Technique with Fast and Efficient Performance for PMSG-Based Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    S. Heshmatian

    2018-03-01

    Full Text Available Wind energy is one of the most promising renewable energy resources. Due to instantaneous variations of the wind speed, an appropriate Maximum Power Point Tracking (MPPT method is necessary for maximizing the captured energy from the wind at different speeds. The most commonly used MPPT algorithms are Tip Speed Ratio (TSR, Power Signal Feedback (PSF, Optimal Torque Control (OTC and Hill Climbing Search (HCS. Each of these algorithms has some advantages and also some major drawbacks. In this paper, a novel hybrid MPPT algorithm is proposed which modifies the conventional methods in a way that eliminates their drawbacks and yields an improved performance. This proposed algorithm is faster in tracking the maximum power point and provides a more accurate response with lower steady state error. Moreover, it presents a great performance under conditions with intensive wind speed variations. The studied Wind Energy Conversion System (WECS consists of a Permanent Magnet Synchronous Generator (PMSG connected to the dc link through a Pulse-Width Modulated (PWM rectifier. The proposed algorithm and the conventional methods are applied to this WECS and their performances are compared using the simulation results. These results approve the satisfactory performance of the proposed algorithm and its notable advantages over the conventional methods.

  3. Biaxial Solar Tracking System Based on the MPPT Approach Integrating ICTs for Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Raúl Gregor

    2015-01-01

    Full Text Available The smart grid and distributed generation based on renewable energy applications often involve the use of information and communication technology (ICT coupled with advanced control and monitoring algorithms to improve the efficiency and reliability of the electrical grid and renewable generation systems. Photovoltaic (PV systems have been recently applied with success in the fields of distributed generation due to their lower environmental impact where the electrical energy generation is related to the amount of solar irradiation and thus the angle of incident ray of the sun on the surface of the modules. This paper introduces an integration of ICTs in order to achieve the maximum power point tracking (MPPT using a biaxial solar tracking system for PV power applications. To generate the references for the digital control of azimuth and elevation angles a Global Positioning System (GPS by satellites is used which enables acquiring the geographic coordinates of the sun in real-time. As a total integration of the system a communication platform based on the 802.15.4 protocol for the wireless sensor networks (WSNs is adopted for supervising and monitoring the PV plant. A 2.4 kW prototype system is implemented to validate the proposed control scheme performance.

  4. An Improved MPPT Algorithm for PV Generation Applications Based on P-U Curve Reconstitution

    Directory of Open Access Journals (Sweden)

    Yaoqiang Wang

    2016-01-01

    Full Text Available The output power of PV array changes with the variation of environmental factors, such as temperature and solar irradiation. Therefore, a maximum power point (MPP tracking (MPPT algorithm is essential for the photovoltaic generation system. However, the P-U curve changes dynamically with the variation of the environmental factors; here, the misjudgment may occur if a simple perturb-and-observe (P&O MPPT algorithm is used. In order to solve this problem, this paper takes MPPT as the main research object, and an improved MPPT algorithm for PV generation applications based on P-U curve reconstitution is proposed. Firstly, the mathematical model of PV array is presented, and then the output dynamic characteristics are analyzed. Based on this, a P-U curve reconstitution strategy is introduced, and the improved MPPT algorithm is proposed. At last, simulation and comparative analysis are conducted. Results show that, with the proposed algorithm, MPP is tracked accurately, and the misjudgment problem is solved effectively.

  5. Multi-Input Converter with MPPT Feature for Wind-PV Power Generation System

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2013-01-01

    Full Text Available A multi-input converter (MIC to process wind-PV power is proposed, designed, analyzed, simulated, and implemented. The MIC cannot only process solar energy but deal with wind power, of which structure is derived from forward-type DC/DC converter to step-down/up voltage for charger systems, DC distribution applications, or grid connection. The MIC comprises an upper modified double-ended forward, a lower modified double-ended forward, a common output inductor, and a DSP-based system controller. The two modified double-ended forwards can operate individually or simultaneously so as to accommodate the variation of the hybrid renewable energy under different atmospheric conditions. While the MIC operates at interleaving mode, better performance can be achieved and volume also is reduced. The proposed MIC is capable of recycling the energy stored in the leakage inductance and obtaining high step-up output voltage. In order to draw maximum power from wind turbine and PV panel, perturb-and-observe method is adopted to achieve maximum power point tracking (MPPT feature. The MIC is constructed, analyzed, simulated, and tested. Simulations and hardware measurements have demonstrated the feasibility and functionality of the proposed multi-input converter.

  6. Chaos Quantum-Behaved Cat Swarm Optimization Algorithm and Its Application in the PV MPPT

    Directory of Open Access Journals (Sweden)

    Xiaohua Nie

    2017-01-01

    Full Text Available Cat Swarm Optimization (CSO algorithm was put forward in 2006. Despite a faster convergence speed compared with Particle Swarm Optimization (PSO algorithm, the application of CSO is greatly limited by the drawback of “premature convergence,” that is, the possibility of trapping in local optimum when dealing with nonlinear optimization problem with a large number of local extreme values. In order to surmount the shortcomings of CSO, Chaos Quantum-behaved Cat Swarm Optimization (CQCSO algorithm is proposed in this paper. Firstly, Quantum-behaved Cat Swarm Optimization (QCSO algorithm improves the accuracy of the CSO algorithm, because it is easy to fall into the local optimum in the later stage. Chaos Quantum-behaved Cat Swarm Optimization (CQCSO algorithm is proposed by introducing tent map for jumping out of local optimum in this paper. Secondly, CQCSO has been applied in the simulation of five different test functions, showing higher accuracy and less time consumption than CSO and QCSO. Finally, photovoltaic MPPT model and experimental platform are established and global maximum power point tracking control strategy is achieved by CQCSO algorithm, the effectiveness and efficiency of which have been verified by both simulation and experiment.

  7. Chaos Quantum-Behaved Cat Swarm Optimization Algorithm and Its Application in the PV MPPT.

    Science.gov (United States)

    Nie, Xiaohua; Wang, Wei; Nie, Haoyao

    2017-01-01

    Cat Swarm Optimization (CSO) algorithm was put forward in 2006. Despite a faster convergence speed compared with Particle Swarm Optimization (PSO) algorithm, the application of CSO is greatly limited by the drawback of "premature convergence," that is, the possibility of trapping in local optimum when dealing with nonlinear optimization problem with a large number of local extreme values. In order to surmount the shortcomings of CSO, Chaos Quantum-behaved Cat Swarm Optimization (CQCSO) algorithm is proposed in this paper. Firstly, Quantum-behaved Cat Swarm Optimization (QCSO) algorithm improves the accuracy of the CSO algorithm, because it is easy to fall into the local optimum in the later stage. Chaos Quantum-behaved Cat Swarm Optimization (CQCSO) algorithm is proposed by introducing tent map for jumping out of local optimum in this paper. Secondly, CQCSO has been applied in the simulation of five different test functions, showing higher accuracy and less time consumption than CSO and QCSO. Finally, photovoltaic MPPT model and experimental platform are established and global maximum power point tracking control strategy is achieved by CQCSO algorithm, the effectiveness and efficiency of which have been verified by both simulation and experiment.

  8. Photovoltaic Power System with MPPT Functionality for a Small-Size Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Jianming Xu

    2014-01-01

    Full Text Available Electric vehicles are recognized as the best replacement of petrol vehicles in the future. However, there are several problems hampering their development, such as the short life span of batteries, poor performance of start-up, and a short driving range. In order to resolve these problems, a hybrid power system based on photovoltaic (PV cells, supercapacitors, and batteries is proposed. This paper focuses on PV cells using a maximum power point track (MPPT system based on a BUCK chopper circuit. Moreover, a novel MPPT algorithm named sectional variable step climbing (SVSC algorithm was proposed. To validate the proposed system, two main experiments have been done. The first experiment showed that the MPP of PV cells was tracked perfectly by use of this photovoltaic power system. The second one showed that the efficiency of SVSC was higher than two existing MPPT methods, the climbing algorithm and the open-circuit voltage (OCV algorithm.

  9. A single phase photovoltaic inverter control for grid connected system

    Indian Academy of Sciences (India)

    tracking (MPPT) controller is used which enables the maximum power extraction under varying irradiation and temperature conditions. The validity of the proposed system is verified through simulation as well as hardware implementation. Keywords. Current controller; MPPT; photovoltaic; PLL; PV inverter; voltage controller.

  10. Modeling and simulation of stand-alone hybrid power system with fuzzy MPPT for remote load application

    Directory of Open Access Journals (Sweden)

    Bogaraj T.

    2015-09-01

    Full Text Available Many parts of remote locations in the world are not electrified even in this Advanced Technology Era. To provide electricity in such remote places renewable hybrid energy systems are very much suitable. In this paper PV/Wind/Battery Hybrid Power System (HPS is considered to provide an economical and sustainable power to a remote load. HPS can supply the maximum power to the load at a particular operating point which is generally called as Maximum Power Point (MPP. Fuzzy Logic based MPPT (FLMPPT control method has been implemented for both Solar and Wind Power Systems. FLMPPT control technique is implemented to generate the optimal reference voltage for the first stage of DC-DC Boost converter in both the PV and Wind energy system. The HPS is tested with variable solar irradiation, temperature, and wind speed. The FLMPPT method is compared with P&O MPPT method. The proposed method provides a good maximum power operation of the hybrid system at all operating conditions. In order to combine both sources, the DC bus voltage is made constant by employing PI Controllers for the second stage of DC-DC Buck-Boost converter in both Solar and Wind Power Systems. Battery Bank is used to store excess power from Renewable Energy Sources (RES and to provide continuous power to load when the RES power is less than load power. A SPWM inverter is designed to convert DC power into AC to supply three phase load. An LC filter is also used at the output of inverter to get sinusoidal current from the PWM inverter. The entire system was modeled and simulated in Matlab/Simulink Environment. The results presented show the validation of the HPS design.

  11. PV inverter test setup for European efficiency, static and dynamic MPPT efficiency evaluation

    DEFF Research Database (Denmark)

    Sera, Dezso; Teodorescu, Remus; Valentini, Massimo

    2008-01-01

    (Denmark) on a commercial transformerless PV inverter. Thanks to the available experimental test setups, that provide the required high measuring accuracy, and the developed PV simulator, which is required for MPPT performance evaluation, PV Inverters can be pretested before being tested by accredited...

  12. New MPPT algorithm for PV applications based on hybrid dynamical approach

    KAUST Repository

    Elmetennani, Shahrazed

    2016-10-24

    This paper proposes a new Maximum Power Point Tracking (MPPT) algorithm for photovoltaic applications using the multicellular converter as a stage of power adaptation. The proposed MPPT technique has been designed using a hybrid dynamical approach to model the photovoltaic generator. The hybrid dynamical theory has been applied taking advantage of the particular topology of the multicellular converter. Then, a hybrid automata has been established to optimize the power production. The maximization of the produced solar energy is achieved by switching between the different operative modes of the hybrid automata, which is conditioned by some invariance and transition conditions. These conditions have been validated by simulation tests under different conditions of temperature and irradiance. Moreover, the performance of the proposed algorithm has been then evaluated by comparison with standard MPPT techniques numerically and by experimental tests under varying external working conditions. The results have shown the interesting features that the hybrid MPPT technique presents in terms of performance and simplicity for real time implementation.

  13. Matlab-Based Modeling and Simulations to Study the Performance of Different MPPT Techniques Used for Photovoltaic Systems under Partially Shaded Conditions

    Directory of Open Access Journals (Sweden)

    Jehun Hahm

    2015-01-01

    Full Text Available A pulse-width-modulator- (PWM- based sliding mode controller is developed to study the effects of partial shade, temperature, and insolation on the performance of maximum power point tracking (MPPT used in photovoltaic (PV systems. Under partially shaded conditions and temperature, PV array characteristics become more complex, with multiple power-voltage maxima. MPPT is an automatic control technique to adjust power interfaces and deliver power for a diverse range of insolation values, temperatures, and partially shaded modules. The PV system is tested using two conventional algorithms: the Perturb and Observe (P&O algorithm and the Incremental Conductance (IncCond algorithm, which are simple to implement for a PV array. The proposed method applied a model to simulate the performance of the PV system for solar energy usage, which is compared to the conventional methods under nonuniform insolation improving the PV system utilization efficiency and allowing optimization of the system performance. The PWM-based sliding mode controller successfully overcomes the issues presented by nonuniform conditions and tracks the global MPP. In this paper, the PV system consists of a solar module under shade connected to a boost converter that is controlled by three different algorithms and is generated using Matlab/Simulink.

  14. Solar Panel System for Street Light Using Maximum Power Point Tracking (MPPT Technique

    Directory of Open Access Journals (Sweden)

    Wiedjaja A.

    2014-03-01

    Full Text Available Solar energy is one form of the renewable energy which is very abundant in regions close to the equator. One application of solar energy is for street light. This research focuses on using the maximum power point tracking technique (MPPT, particularly the perturb and observe (P&O algorithm, to charge battery for street light system. The proposed charger circuit can achieve 20.73% higher power efficiency compared to that of non-MPPT charger. We also develop the LED driver circuit for the system which can achieve power efficiency up to 91.9% at a current of 1.06 A. The proposed street lightning system can be implemented with a relatively low cost for public areas.

  15. IMPROVED VARIABLE STEP SIZE INCREMENTAL CONDUCTANCE MPPT METHOD WITH HIGH CONVERGENCE SPEED FOR PV SYSTEMS

    Directory of Open Access Journals (Sweden)

    BEHZAD AZIZIAN ISALOO

    2016-04-01

    Full Text Available Maximum power point tracking (MPPT algorithms are employed in photovoltaic (PV systems to provide full utilization of PV array output power. Among all the MPPT algorithms, the Incremental Conductance (INC algorithm is widely used in PV systems due to the high tracking speed and accuracy. In this paper an improved variable step size algorithm which is based on incremental conductance algorithm is proposed that adjusts the step size according to PV output current. The result of this adaption is to make the algorithm suitable for practical operating conditions due to a wider operating range of irradiation changes. Simulation results confirm that the proposed algorithm increases convergence speed and efficiency in comparison with conventional fixed and variable step size INC algorithms.

  16. A High Efficiency Boost Converter with MPPT Scheme for Low Voltage Thermoelectric Energy Harvesting

    Science.gov (United States)

    Guan, Mingjie; Wang, Kunpeng; Zhu, Qingyuan; Liao, Wei-Hsin

    2016-11-01

    Using thermoelectric elements to harvest energy from heat has been of great interest during the last decade. This paper presents a direct current-direct current (DC-DC) boost converter with a maximum power point tracking (MPPT) scheme for low input voltage thermoelectric energy harvesting applications. Zero current switch technique is applied in the proposed MPPT scheme. Theoretical analysis on the converter circuits is explored to derive the equations for parameters needed in the design of the boost converter. Simulations and experiments are carried out to verify the theoretical analysis and equations. A prototype of the designed converter is built using discrete components and a low-power microcontroller. The results show that the designed converter can achieve a high efficiency at low input voltage. The experimental efficiency of the designed converter is compared with a commercial converter solution. It is shown that the designed converter has a higher efficiency than the commercial solution in the considered voltage range.

  17. FUZZY LOGIC CONTROLLER IMPLEMENTATION FOR PHOTOVOLTAIC STATION

    Directory of Open Access Journals (Sweden)

    Imad Zein

    2014-01-01

    Full Text Available 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. This is why the controllers of all solar power electronic converters employ some method for maximum power point tracking (MPPT . Over the past years many MPPT techniques have been published and based on that the main paper’s objective is to analyze one of the most promising MPPT control algorithms: fuzzy logic controller

  18. Photovoltaic Power System with MPPT Functionality for a Small-Size Electric Vehicle

    OpenAIRE

    Xu, Jianming; Kang, Longyun; Zhong, Changyi; Cao, Binggang

    2014-01-01

    Electric vehicles are recognized as the best replacement of petrol vehicles in the future. However, there are several problems hampering their development, such as the short life span of batteries, poor performance of start-up, and a short driving range. In order to resolve these problems, a hybrid power system based on photovoltaic (PV) cells, supercapacitors, and batteries is proposed. This paper focuses on PV cells using a maximum power point track (MPPT) system based on a BUCK chopper cir...

  19. Dynamic response evaluation of sensorless MPPT method for hybrid PV-DFIG wind turbine system

    Directory of Open Access Journals (Sweden)

    Danvu Nguyen

    2016-01-01

    Full Text Available This research proposes a sensorless Maximum Power Point Tracking (MPPT method for a hybrid Photovoltaic-Wind system, which consists of Photovoltaic (PV system and Doubly-Fed Induction Generator (DFIG Wind Turbine. In the hybrid system, the DC/DC converter output of the PV system is directly connected to the DC-link of DFIG’s back-to-back converter. Therefore, the PV inverter and its associated circuit can be removed in this structure. Typically, the PV power is monitored by using PV current sensor and PV voltage sensor for MPPT. In this paper, the powers of converters on grid side and rotor side of DFIG are used to estimate the PV power without the PV current sensor. That can efficiently reduce the cost of the hybrid system. The detailed analysis of the sensorless MPPT method, which includes derived equations and operation response, is also presented in this paper. In addition, an overview of PV-DFIG research in literature is stated to supply comprehensive knowledge of related research.

  20. AC/DC Smart Control And Power Sharing of DC Distribution Systems

    Science.gov (United States)

    2012-02-10

    input voltage and output current variations, a voltage feedback signal is needed. Moreover, if current control or maximum power point tracking ( MPPT ) is...ic character tuations in ). The figu MPPT ) de-r rent charact a boost co nd its DC v de-rate the ich is not de tions at the to smooth t s of PB

  1. Open- and Short-Circuit Fault Identification for a Boost dc/dc Converter in PV MPPT Systems

    Directory of Open Access Journals (Sweden)

    Diego R. Espinoza Trejo

    2018-03-01

    Full Text Available This paper proposes a fault identification system for short and open-circuit switch faults (SOCSF for a dc/dc converter acting as a Maximum Power Point Tracker (MPPT in Photovoltaic (PV systems. A closed-loop operation is assumed for the boost dc/dc converter. A linearizing control plus a Proportional-Derivative (PD controller is suggested for PV voltage regulation at the maximum power point (MPP. In this study, the SOCSF are modeled by using an additive fault representation and the fault identification (FI system is synthesized departing from a Luenberger observer. Hence, an FI signal is obtained, which is insensitive to irradiance and load current changes, but affected by the SOCSF. For FI purposes, only the sensors used in the control system are needed. Finally, an experimental evaluation is presented by using a solar array simulator dc power supply and a boost dc/dc converter of 175 W in order to validate the ideas this study exposes.

  2. Integration of Hybrid PV/Wind Generation System Using Fuzzy MPPT in Grid Connected System for Remote Area

    Directory of Open Access Journals (Sweden)

    Soedibyo

    2016-01-01

    Full Text Available Photovoltaic and wind are renewable energy resources that widely used and grow rapidly in fulfilling electricity demand. Powers from both technologies depend on sunlight intensity and wind speed. For small scale power generation, DC voltage from both technologies is low and requires step-up converter to raise DC voltage ratio before converted into AC voltage. To optimize this system, step-up converter must have high ratio and efficiency to a distance of wide voltage input. This paper proposed an operation simulation and arrangement of DC-DC converter along with DC-AC from hybrid source PV-Wind which integrated to grid utilities without using storage device. High Gain Integrated Cascade Boost (HGICB is DC-DC converter that has quadratic voltage ratio and used in this research. Then DC link connected to Voltage Source Inverter (VSI which interconnected with utility grid and controlled by current control method. The total installed capacity of hybrid source is 4.4 kW. Wind turbine uses PMSG along with full bridge rectifier. To maximize and stabilize the generated power, MPPT fuzzy is used. Result from the simulation shows that converter capable to maintain maximum power whether from PV and wind turbine which canalized to utility grid in various irradiation condition, wind speed, and grid load alteration.

  3. An Analysis of Variable-Speed Wind Turbine Power-Control Methods with Fluctuating Wind Speed

    Directory of Open Access Journals (Sweden)

    Seung-Il Moon

    2013-07-01

    Full Text Available Variable-speed wind turbines (VSWTs typically use a maximum power-point tracking (MPPT method to optimize wind-energy acquisition. MPPT can be implemented by regulating the rotor speed or by adjusting the active power. The former, termed speed-control mode (SCM, employs a speed controller to regulate the rotor, while the latter, termed power-control mode (PCM, uses an active power controller to optimize the power. They are fundamentally equivalent; however, since they use a different controller at the outer control loop of the machine-side converter (MSC controller, the time dependence of the control system differs depending on whether SCM or PCM is used. We have compared and analyzed the power quality and the power coefficient when these two different control modes were used in fluctuating wind speeds through computer simulations. The contrast between the two methods was larger when the wind-speed fluctuations were greater. Furthermore, we found that SCM was preferable to PCM in terms of the power coefficient, but PCM was superior in terms of power quality and system stability.

  4. Maximum Power Point Tracking Control of a Thermoelectric Generation System Using the Extremum Seeking Control Method

    Directory of Open Access Journals (Sweden)

    Ssennoga Twaha

    2017-12-01

    Full Text Available This study proposes and implements maximum power Point Tracking (MPPT control on thermoelectric generation system using an extremum seeking control (ESC algorithm. The MPPT is applied to guarantee maximum power extraction from the TEG system. The work has been carried out through modelling of thermoelectric generator/dc-dc converter system using Matlab/Simulink. The effectiveness of ESC technique has been assessed by comparing the results with those of the Perturb and Observe (P&O MPPT method under the same operating conditions. Results indicate that ESC MPPT method extracts more power than the P&O technique, where the output power of ESC technique is higher than that of P&O by 0.47 W or 6.1% at a hot side temperature of 200 °C. It is also noted that the ESC MPPT based model is almost fourfold faster than the P&O method. This is attributed to smaller MPPT circuit of ESC compared to that of P&O, hence we conclude that the ESC MPPT method outperforms the P&O technique.

  5. Comparison of two methods for the control of gastrointestinal nematodes in lambs and ewes/ Comparação de dois métodos de controle de nematódeos gastrintestinais em borregas e ovelhas de corte

    Directory of Open Access Journals (Sweden)

    Iali da Silva Oliveira

    2008-08-01

    Full Text Available The objective of this work was to evaluate the control of nematode gastrintestinal on ovine meat breeds in Voisin pasturing system during one grazing year. The experiment was carried out at the Research Center Farm of the Passo Fundo University during the period of June 2005 to July 2006. The animals were kept in 85 pasture blocks with 810 square meters each. In the experiment 42 ewe hoggets and 42 Suffolk, Ile de France purebreed and crosses ewes were subdivided in four groups composed of 21 animals each. The groups had been assigned as G1 (traditional sheep, G2 (traditional young ewes both treated every 60 days with Levamisole; the groups G3 (Famacha® sheep and G4 (Famacha® young ewes were evaluated by the Famacha® method. The following variables were evaluated: live weight and worm egg counts (EPG. In relation to the live weights it was proven that it did not have statistics difference (P>0,05 between ewe hoggets and adult sheep of the traditional groups when compared with the ones of the Famacha® method. Differences in EPG counts during of the year in the ewe hoggets were found it had a significant reduction in the frequency of treatments for the Famacha® method when compared with the traditional method, of 90,39% for ewe hoggets and 90.93% for the sheep, becoming this method a viable alternative.Este trabalho teve como objetivo avaliar o controle de helmintos gastrintestinais em ovinos de corte em um sistema de pastoreio Voisin em quatro estações do ano. Foi realizado no Centro de Pesquisa Agropecuária da Universidade Passo Fundo no período de junho de 2005 a julho de 2006. Foram utilizados 84 fêmeas das raças Suffolk, Ile de France puras e mestiças as quais foram subdivididas em quatro grupos composto de 21 animais cada. Os grupos foram designados como G1 (ovelha tradicional, G2 (borrega tradicional tratadas a cada 60 dias com Levamisole; os grupos G3 (ovelha Famacha®, e G4 (borrega Famacha® foram avaliadas pelo m

  6. Performance optimization of a hybrid micro-grid based on double-loop MPPT and SVC-MERS

    Science.gov (United States)

    Wei, Yewen; Hou, Xilun; Zhang, Xiang; Xiong, Shengnan; Peng, Fei

    2018-02-01

    With ever-increasing concerns on environmental pollution and energy shortage, the development of renewable resource has attracted a lot of attention. This paper first reviews both the wind and photovoltaic (PV) generation techniques and approaches of micro-grid voltage control. Then, a novel islanded micro-grid, which consists of wind & PV generation and hybrid-energy storage device, is built for application to remote and isolated areas. For the PV power generation branch, a double- maximum power point tracking (MPPT) technique is developed to trace the sunlight and regulate the tilt angle of PV panels. For wind-power generation branch, squirrel cage induction generator (SCIG) is used as its simple structure, robustness and less cost. In order to stabilize the output voltage of SCIGs, a new Static Var Compensator named magnetic energy recovery switch (SVC-MERS) is applied. Finally, experimental results confirm that both of the proposed methods can improve the efficiency of PV power generation and voltage stability of the micro-grid, respectively.

  7. On the Perturb-and-Observe and Incremental Conductance MPPT methods for PV systems

    DEFF Research Database (Denmark)

    Sera, Dezso; Mathe, Laszlo; Kerekes, Tamas

    2013-01-01

    This paper presents a detailed analysis of the two most well-known hill-climbing MPPT algorithms, the Perturb-and-Observe (P&O) and Incremental Conductance (INC). The purpose of the analysis is to clarify some common misconceptions in the literature regarding these two trackers, therefore helping...... according to the EN 50530 standard, resulting in a deviation between their efficiencies of 0.13% in dynamic, and as low as 0.02% in static conditions. The results show that despite the common opinion in the literature, the P&O and INC are equivalent....

  8. A Low-disturbance Diagnostic Function Integrated in the PV Arrays’ MPPT Algorithm

    DEFF Research Database (Denmark)

    Sera, Dezso; Mathe, Laszlo; Kerekes, Tamas

    2011-01-01

    This paper focuses on the estimation of series resistance changes for flat silicone PV panels or arrays during operation, without moving the operating point far away from the Maximum Power Point. The method is based on the measurement of the slope of the IV curve at a current level that differs...... from the short-circuit current with a fixed value, regardless of irradiance conditions. The method causes less power loss and power ripple due to measurements and it is easily integrated in a hill-climbing MPPT algorithm....

  9. A novel hybrid MPPT technique for solar PV applications using perturb & observe and fractional open circuit voltage techniques

    OpenAIRE

    Murtaza, Ali Faisal; Sher, H.; Chiaberge, Marcello; Boero, Diego; De Giuseppe, Mirko; Addoweesh, K.

    2012-01-01

    Solar photovoltaic (PV) systems have been an area of active research for the last few decades to improve the efficiency of solar PV module. The non-linear nature of IV curve of solar PV module demands some technique to track the maximum voltage and maximum current point on IV curve corresponding to Maximum Power Point(MPP). Thus, Maximum Power Point Tracking (MPPT) techniques are widely deployed for this purpose. Lot of MPPT techniques have been developed in recent past but still most commerc...

  10. Functional Study of A Distributed MPPT Power Management System

    Directory of Open Access Journals (Sweden)

    Bifaretti S.

    2017-01-01

    Full Text Available This paper presents the concept of a control strategy for Solar Array (SA power regulation using an independent Maximum Power Point Tracking system for each Solar Array section in order to maximize the power extracted from every SA sections. Moreover, it allows to distribute the battery charge current between the power sources in order to evenly divide the switching losses on the power semiconductors of the converters and, thus, extending their life time and to reduce the dissipation power. The proposed strategy can be applied to the Power Control Unit designed for satellites with unregulated power bus architecture. Significant simulation results, obtained using a Matlab/Simulink model, demonstrates the validity of the proposed approach.

  11. Piezoelectric energy harvester interface with real-time MPPT

    Science.gov (United States)

    Elliott, A. D. T.; Mitcheson, P. D.

    2014-11-01

    Power of resonant piezoelectric harvesters can be severely limited if the damping force cannot be dynamically altered as the mechanical excitation level changes. The singlesupply pre-biasing (SSPB) technique enables the Coulomb damping force to be set by a single voltage and so by varying that voltage, real-time adaptation to variations in the mechanical force can be implemented. Similarly the conduction angle of a diode bridge rectifier circuit can be altered by changing the biasing voltage applied. This paper presents a method of achieving this by altering the amount of energy transferred from the pre-biasing capacitor used in SSPB and the diode bridge rectifier to a storage battery via a buck converter. The control system was implemented on a FPGA and consumed 50 μW.

  12. Global Maximum Power Point Tracking (MPPT of a Photovoltaic Module Array Constructed through Improved Teaching-Learning-Based Optimization

    Directory of Open Access Journals (Sweden)

    Kuei-Hsiang Chao

    2016-11-01

    Full Text Available The present study proposes a maximum power point tracking (MPPT method in which improved teaching-learning-based optimization (I-TLBO is applied to perform global MPPT of photovoltaic (PV module arrays under dissimilar shading situations to ensure the maximum power output of the module arrays. The proposed I-TLBO enables the automatic adjustment of teaching factors according to the self-learning ability of students. Incorporating smart-tracking and self-study strategies can effectively improve the tracking response speed and steady-state tracking performance. To evaluate the feasibility of the proposed I-TLBO, a HIP-2717 PV module array from Sanyo Electric was employed to compose various arrays with different serial and parallel configurations. The arrays were operated under different shading conditions to test the MPPT with double, triple, or quadruple peaks of power-voltage characteristic curves. Boost converters were employed with TMS320F2808 digital signal processors to test the proposed MPPT method. Empirical results confirm that the proposed method exhibits more favorable dynamic and static-state response tracking performance compared with that of conventional TLBO.

  13. Randomized controlled trial of two methods of nasal continuous positive airway pressure (N-CPAP) in preterm infants with respiratory distress syndrome: underwater bubbly CPAP vs. Medijet system device.

    Science.gov (United States)

    Hosseini, Mohammad Bagher; Heidarzadeh, Mohammad; Balila, Masumeh; Ghojazadeh, Morteza; Janani, Raheleh; Safavi-nia, Sima; Naghavi-Behzad, Mohammad; Alikhah, Hossein

    2012-01-01

    There has been an increasing interest in the application of non-invasive respiratory support in preterm infants, and different types of nasal continuous positive airway pressure (N-CPAP) devices are being used in Neonatal Intensive Care Units (NICUs). The objective of the present study was to compare the duration of CPAP need and possible complications of two methods of (N-CPAP) delivery: Bubble CPAP (B-CPAP) and Medijet (MJ) system device in preterm infants with respiratory distress syndrome (RDS). This prospective randomized clinical trial was performed on 161 preterm infants (28-37 weeks of gestational age) with RDS and eligible for CPAP therapy. The infants were inborn and admitted in a level III NICU of Al-Zahra Teaching Hospital (Tabriz, Iran) from April 2010 to September 2011. All infants were randomized in the first hour of life to B-CPAP or MJ system. Short binasal prongs were used in both groups and CPAP was set at the level of 5-6 cm H2O. The primary outcome of this study was duration of CPAP need (hour). Other outcomes, such as complications of the two methods of N-CPAP, were evaluated using a checklist. Ninety infants were randomized to the MJ system, and 71 were randomized to B-CPAP. The mean gestational age and birth weight were similar in the two groups, as was the duration of CPAP need (44.3 ± 20.64 vs. 49.2 ± 21.2 hours, respectively; p=0.66). Moreover, the probability of complications, such as CPAP failure rate, pulmonary hemorrhage, pneumothorax, intraventricular hemorrhage, abdominal distention, necrotizing enterocolitis, and bronchopulmonary dysplasia, was the same between the two study groups (p>0.05). There was a trend of more hyperemia of the nose in the B-CPAP group in comparison to the MJ system group (10% versus 3.3%, respectively), but the difference was not significant (p=0.08). In conclusion, the MJ system is as effective as B-CPAP in the management of infants with RDS.

  14. Photovoltaic System Equipped with Digital Command Control and Acquisition

    OpenAIRE

    Yaden, Med; Melhaoui, Mustapha; Gaamouche, Rajae; Hirech, Kamal; Baghaz, Elhadi; Kassmi, Khalil

    2013-01-01

    In this paper, we present results concerning the design, the realization and the characterization of a photovoltaic system (PV), equipped with a digital controls: Power Point Tracking (MPPT), charge/discharge lead acid batteries, sun tracker and supervision. These different functions are performed with a microcontroller that has capabilities and functions to the reliability of PV systems (signal generation Pulses Width Modulation (PWM), speed etc.). Concerning the MPPT control operation, we i...

  15. MPPT Algorithm Development for Laser Powered Surveillance Camera Power Supply Unit

    Science.gov (United States)

    Zhang, Yungui; Dushantha Chaminda, P. R.; Zhao, Kun; Cheng, Lin; Jiang, Yi; Peng, Kai

    2018-03-01

    Photovoltaics (PV) cells, modules which are semiconducting materials, convert light energy into electricity. Operation of a PV cell requires 3 basic features. When the light is absorbed it generate pairs of electron holes or excitons. An external circuit carrier opposite types of electrons irrespective of the source (sunlight or LASER light). The PV arrays have photovoltaic effect and the PV cells are defined as a device which has electrical characteristics: such as current, voltage and resistance. It varies when exposed to light, that the power output is depend on direct Laser-light. In this paper Laser-light to electricity by direct conversion with the use of PV cells and its concept of Band gap Energy, Series Resistance, Conversion Efficiency and Maximum Power Point Tracking (MPPT) methods [1].

  16. An Improved Particle Swarm Optimization(PSO-Based MPPT Strategy for PV System

    Directory of Open Access Journals (Sweden)

    Wei Tianmeng

    2017-01-01

    Full Text Available Under partially shaded conditions, the P-U curve of PV array contains multiple extreme points. General MPPT methods may misjudge the MPP and trap in the local extreme point, which will cause low working efficiency. Although the traditional PSO algorithm can accurately track the maximum power point under this condition, the optimizing process fluctuates obviously and the tracking speed can be improved. In order to solve these problems, an improved PSO algorithm is proposed. The initial positions of the particles are located by analysing the relationship of the I-U and P-U characteristic curves. It is more closed to the maximum power point. So the efficiency of PSO algorithm is improved. To evaluate the effectiveness of this method, the simulation model is established in MATLAB/Simulink. Under partially shaded conditions the algorithm can track the maximum power point quickly and accurately.

  17. Enhanced Grey Wolf Optimizer based MPPT Algorithm of PV system under Partial Shaded Condition

    Directory of Open Access Journals (Sweden)

    Santhan Kumar Cherukuri

    2017-11-01

    Full Text Available Partial shading condition is one of the adverse phenomena which effects the power output of photovoltaic (PV systems due to inaccurate tracking of global maximum power point. Conventional Maximum Power Point Tracking (MPPT techniques like Perturb and Observe, Incremental Conductance and Hill Climbing can track the maximum power point effectively under uniform shaded condition, but fails under partial shaded condition. An attractive solution under partial shaded condition is application of meta-heuristic algorithms to operate at global maximum power point. Hence in this paper, an Enhanced Grey Wolf Optimizer (EGWO based maximum power point tracking algorithm is proposed to track the global maximum power point of PV system under partial shading condition. A Mathematical model of PV system is developed under partial shaded condition using single diode model and EGWO is applied to track global maximum power point. The proposed method is programmed in MATLAB environment and simulations are carried out on 4S and 2S2P PV configurations for dynamically changing shading patterns. The results of the proposed method are analyzed and compared with GWO and PSO algorithms. It is observed that proposed method is effective in tracking global maximum power point with more accuracy in less computation time compared to other methods. Article History: Received June 12nd 2017; Received in revised form August 13rd 2017; Accepted August 15th 2017; Available online How to Cite This Article: Kumar, C.H.S and Rao, R.S. (2017 Enhanced Grey Wolf Optimizer Based MPPT Algorithm of PV System Under Partial Shaded Condition. Int. Journal of Renewable Energy Development, 6(3, 203-212. https://doi.org/10.14710/ijred.6.3.203-212

  18. Noble-TLBO MPPT Technique and its Comparative Analysis with Conventional methods implemented on Solar Photo Voltaic System

    Science.gov (United States)

    Patsariya, Ajay; Rai, Shiwani; Kumar, Yogendra, Dr.; Kirar, Mukesh, Dr.

    2017-08-01

    The energy crisis particularly with developing GDPs, has bring up to a new panorama of sustainable power source like solar energy, which has encountered huge development. Progressively high infiltration level of photovoltaic (PV) era emerges in keen matrix. Sunlight based power is irregular and variable, as the sun based source at the ground level is exceedingly subject to overcast cover inconstancy, environmental vaporized levels, and other climate parameters. The inalienable inconstancy of substantial scale sun based era acquaints huge difficulties with keen lattice vitality administration. Exact determining of sun powered power/irradiance is basic to secure financial operation of the shrewd framework. In this paper a noble TLBO-MPPT technique has been proposed to address the vitality of solar energy. A comparative analysis has been presented between conventional PO, IC and the proposed MPPT technique. The research has been done on Matlab Simulink software version 2013.

  19. Maximum Power Angle (MPA) Based Maximum Power Point Tracking (MPPT) Technique for Efficiency Optimization of Solar PV System

    OpenAIRE

    SHARMA, DINESH KUMAR; Purohit, Ghanshyam

    2016-01-01

    A novel maximum power angle (MPA) based maximum power point tracking (MPPT) technique is reported. In this technique, a graphical and mathematical approach based maximum power angle determination mechanism is adopted. On the I-V characteristic curve, the angle made from the intersection point of open circuit voltage (VOC) and short circuit current (ISC) with respect to the voltage (V) axis to the point of maximum power (MPP) is determined using the known parameters of the solar PV module. The...

  20. Implementasi Algoritma Perturb and Observe untuk Mengoptimasi Daya Keluaran Solar Cell Menggunakan MPPT di Laboratorium Energi Baru Terbarukan

    Directory of Open Access Journals (Sweden)

    Sri Utami

    2017-02-01

    Full Text Available Energi yang dihasilkan oleh sel surya sangat bervariasi dan sangat tergantung pada kondisi cuaca. Untuk mengoptimasinya digunakan maximum power point. Penelitian ini mengimplementasikan algoritma Perturb and Observe pada Maximum Power Point Tracker (MPPT sebagai kontroller untuk pembangkitan energi surya. Sistem dibangun menggunakan Arduino Uno R3 untuk mengekstraksi daya maksimum panel surya. Microcontroller ini mengontrol DC buck converter dan digunakan untuk charging baterai 6V. Metode ini beroperasi dengan memberi perturbing tegangan atau arus terminal array dan membandingkan daya yang dihasilkan dengan output panel surya. Diperlukan perturbing yang sesuai untuk mendapatkan nilai optimasi yang tepat. Validasi dari panel surya menggunakan metode yang diusulkan pada MPPT-nya memberikan performansi yang lebih baik dibuktikan pada nilai daya dan tegangannya. Menggunakan parameter perturbation 0.1, MPPT mampu mengoptimasi daya ouput panel surya sebesar 24.49 W dengan beban 5 ? dan nilai irradiasi 523 W/m2  dibandingkan dengan metode konvensional dengan beban sama dan nilai irradiasi sebesar 527 W/m2 yang menghasilkan daya keluaran 15.37 W

  1. Intelligent Photovoltaic Maximum Power Point Tracking Controller for Energy Enhancement in Renewable Energy System

    Directory of Open Access Journals (Sweden)

    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.

  2. A Differential Evolution Based MPPT Method for Photovoltaic Modules under Partial Shading Conditions

    Directory of Open Access Journals (Sweden)

    Kok Soon Tey

    2014-01-01

    Full Text Available Partially shaded photovoltaic (PV modules have multiple peaks in the power-voltage (P-V characteristic curve and conventional maximum power point tracking (MPPT algorithm, such as perturbation and observation (P&O, which is unable to track the global maximum power point (GMPP accurately due to its localized search space. Therefore, this paper proposes a differential evolution (DE based optimization algorithm to provide the globalized search space to track the GMPP. The direction of mutation in the DE algorithm is modified to ensure that the mutation always converges to the best solution among all the particles in the generation. This helps to provide the rapid convergence of the algorithm. Simulation of the proposed PV system is carried out in PSIM and the results are compared to P&O algorithm. In the hardware implementation, a high step-up DC-DC converter is employed to verify the proposed algorithm experimentally on partial shading conditions, load variation, and solar intensity variation. The experimental results show that the proposed algorithm is able to converge to the GMPP within 1.2 seconds with higher efficiency than P&O.

  3. Realworld maximum power point tracking simulation of PV system based on Fuzzy Logic control

    Directory of Open Access Journals (Sweden)

    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.

  4. Comparação entre dois métodos de avaliação do controle da asma baseados na percepção individual Comparison between two methods of asthma control evaluation based on individual perception

    Directory of Open Access Journals (Sweden)

    Paula Cristina Andrade Almeida

    2012-06-01

    , Brazil. The patients completed the ACQ-6 and answered a specific additional question in order to evaluate their own perception of asthma control in the previous week. RESULTS: We evaluated 423 patients who met the inclusion criteria. The sample was predominantly female (81.3%, and 64.3% had an income lower than two times the national minimum wage. The mean age was 49.85 ± 13.71 years, and the duration of asthma symptoms was 32.11 ± 16.35 years. The patients had been regularly treated via the program for 36.65 ± 18.10 months. Based on the subjective perception of asthma control, only 8% of the patients considered their asthma to be uncontrolled, whereas 38.8% had an ACQ-6 score > 1.5, which indicates poor control. The kappa statistic revealed poor concordance between the two methods. There was a direct association between uncontrolled asthma and the number of emergency room visits in the previous month (p < 0.001. CONCLUSIONS: In this sample of patients, the subjective perception of asthma control differed from that measured by the ACQ-6 score, and the patients overestimated their own level of asthma control, which puts them at risk of being undertreated.

  5. Simulation Modeling of Intelligent Control Algorithms for Constructing Autonomous Power Supply Systems with Improved Energy Efficiency

    Directory of Open Access Journals (Sweden)

    Gimazov Ruslan

    2018-01-01

    Full Text Available The paper considers the issue of supplying autonomous robots by solar batteries. Low efficiency of modern solar batteries is a critical issue for the whole industry of renewable energy. The urgency of solving the problem of improved energy efficiency of solar batteries for supplying the robotic system is linked with the task of maximizing autonomous operation time. Several methods to improve the energy efficiency of solar batteries exist. The use of MPPT charge controller is one these methods. MPPT technology allows increasing the power generated by the solar battery by 15 – 30%. The most common MPPT algorithm is the perturbation and observation algorithm. This algorithm has several disadvantages, such as power fluctuation and the fixed time of the maximum power point tracking. These problems can be solved by using a sufficiently accurate predictive and adaptive algorithm. In order to improve the efficiency of solar batteries, autonomous power supply system was developed, which included an intelligent MPPT charge controller with the fuzzy logic-based perturbation and observation algorithm. To study the implementation of the fuzzy logic apparatus in the MPPT algorithm, in Matlab/Simulink environment, we developed a simulation model of the system, including solar battery, MPPT controller, accumulator and load. Results of the simulation modeling established that the use of MPPT technology had increased energy production by 23%; introduction of the fuzzy logic algorithm to MPPT controller had greatly increased the speed of the maximum power point tracking and neutralized the voltage fluctuations, which in turn reduced the power underproduction by 2%.

  6. Optimization of partially shaded PV array using a modified P&O MPPT algorithm

    Directory of Open Access Journals (Sweden)

    Abdelaziz YOUCEF

    2016-07-01

    Full Text Available A photovoltaic (PV array generated power is directly affected by temperature, solar irradiation, shading, and array configuration. In practice, PV arrays could be partially shaded by could, buildings, trees and other utilities. In this case, multiple maximums appear in the P-V curve, a global maximum and one or several local maximums. The “perturb and observe“ (P&O maximum power point tracking (MPPT algorithm cannot differentiate between a global and a local maximum and it is therefore ineffective when partial shading occurs. First, this paper presents an original mathematical model of the P-V curve of a partially shaded PV array, that was used to perform a simulation study in order to show the P&O algorithm inability to track the global MPP of a PV array solar system under partial shading for low shading irradiation levels, then an adaptation sub algorithm is proposed to be added to the P&O algorithm in order to give it the ability to track the global MPP. This sub algorithm moves the operating point imposed by the partial shading configuration to a point in the vicinity of the global MPP in order to be easily tracked by the P&O algorithm. In the simulation, a PV array with a hundred modules has been considered by using a light, a medium then a severe shading configuration. The results obtained indicate that the proposed modified P&O algorithm is able to track the global MPP for the considered shading configurations and for any shading irradiation level.

  7. Investigation Results on Solar Array Thermal & Electrical Imbalance Phenomenon on Power Systems Equipped with MPPT

    Science.gov (United States)

    Mercier, F.; Samaniego, B.; Soriano, T.; Beaufils, G.; Fernandez Lisbona, E.; Dettlaff, K.; Jensen, H.

    2014-08-01

    The thermal / electrical imbalance phenomenon on the satellite solar arrays is a common issue inherent to the negative thermal voltage coefficient of the triple junction cells, which is usually already taken into account with basic precautions on the solar panel layout.In the frame of the ESA TRP study "Investigation on Solar Array thermal and electrical imbalance phenomenon on power systems equipped with Maximum Power Point Tracker (MPPT)" performed by Airbus Defence & Space (former Astrium Toulouse and Ottobrunn) and TERMA, in-depth analyses were conducted for the first time to better understand and characterize the secondary maximum power point phenomenon for various representative mission cases, whether in Earth vicinity or not. With the help of a newly developed detailed thermo-electrical coupled solver and a wide range of solar cell characterizations in flux and temperature, multiple sets of simulations were run to simulate realistic solar panel characteristics.The study showed that no secondary false maximum power point can be created on the solar panel characteristic IV curve for missions around Earth vicinity, at the sole exception of critical shadowing cases. Furthermore, the same conclusions apply for missions up to Mars orbit. The only potential threats come from the missions further than Mars (typically Jupiter missions) where various very high heterogeneities could lead to multiple maxima. This is deeply linked to the LILT (low illumination low temperature) conditions applied to the current solar cell triple junction characteristics and shape. Moreover, thermo-electrical imbalances that do not create secondary power point can still seriously grieve the solar array power output performances. This power loss can however be accurately assessed by the newly developed solver in support of in-development missions like Juice.

  8. Comparative study of the reliability of MPPT algorithms for the crystalline silicon photovoltaic modules in variable weather conditions

    Directory of Open Access Journals (Sweden)

    Abraham Dandoussou

    2017-05-01

    Full Text Available The crystalline silicon photovoltaic modules are widely used as power supply sources in the tropical areas where the weather conditions change abruptly. Fortunately, many MPPT algorithms are implemented to improve their performance. In the other hand, it is well known that these power supply sources are nonlinear dipoles and so, their intrinsic parameters may vary with the irradiance and the temperature. In this paper, the MPPT algorithms widely used, i.e. Perturb and Observe (P&O, Incremental Conductance (INC, Hill-Climbing (HC, are implemented using Matlab®/Simulink® model of a crystalline silicon photovoltaic module whose intrinsic parameters were extracted by fitting the I(V characteristic to experimental points. Comparing the simulation results, it is obvious that the variable step size INC algorithm has the best reliability than both HC and P&O algorithms for the near to real Simulink® model of photovoltaic modules. With a 60 Wp photovoltaic module, the daily maximum power reaches 50.76 W against 34.40 W when the photovoltaic parameters are fixed. Meanwhile, the daily average energy is 263 Wh/day against 195 Wh/day.

  9. Optimal Control of Solar Heating System

    KAUST Repository

    Huang, Bin-Juine

    2017-02-21

    Forced-circulation solar heating system has been widely used in process and domestic heating applications. Additional pumping power is required to circulate the water through the collectors to absorb the solar energy. The present study intends to develop a maximum-power point tracking control (MPPT) to obtain the minimum pumping power consumption at an optimal heat collection. The net heat energy gain Qnet (= Qs − Wp/ηe) was found to be the cost function for MPPT. The step-up-step-down controller was used in the feedback design of MPPT. The field test results show that the pumping power is 89 W at Qs = 13.7 kW and IT = 892 W/m2. A very high electrical COP of the solar heating system (Qs/Wp = 153.8) is obtained.

  10. A new MATLAB/Simulink model of triple-junction solar cell and MPPT based on artificial neural networks for photovoltaic energy systems

    Directory of Open Access Journals (Sweden)

    Hegazy Rezk

    2015-09-01

    Full Text Available This paper presents a new Matlab/Simulink model of a PV module and a maximum power point tracking (MPPT system for high efficiency InGaP/InGaAs/Ge triple-junction solar cell. The proposed technique is based on Artificial Neural Network. The equivalent circuit model of the triple-junction solar cell includes the parameters of each sub-cell. It is also include the effect of the temperature variations on the energy gap of each sub-cell as well as the diode reverse saturation currents. The implementation of a PV model is based on the triple-junction solar cell in the form of masked block in Matlab/Simulink software package that has a user-friendly icon and dialog. It is fast and accurate technique to follow the maximum power point. The simulation results of the proposed MPPT technique are compared with Perturb and Observe MPPT technique. The output power and energy of the proposed technique are higher than that of the Perturb and Observe MPPT technique. The proposed technique increases the output energy per day for a one PV module from 3.37 kW h to 3.75 kW h, i.e. a percentage of 11.28%.

  11. Mass primaquine preventive treatment for control ofPlasmodium vivax malariain the Democratic People's Republic of Korea: a country success story.

    Science.gov (United States)

    Pant, Shushil Dev; Chol, Kim Yun; Tegegn, Yonas; Mandal, Partha Pratim; Chol, Ri Kwang

    2014-01-01

    In 1998, the resurgence of Plasmodium vivax malaria in the Democratic People's Republic of Korea quickly increased to an epidemic, with 601 013 cases reported I during 1999-2001. The introduction of mass primaquine preventive treatment (MPPT) in 2002 was followed by a rapid reduction of malaria disease burden. The intervention has been well accepted by the community. Doctors were part of a strong functional health system with the ability to deliver interventions at the household J level. MPPT was considered for control of malaria after a study conducted in two J neighbouring endemic villages (ris) involving 320 healthy adults demonstrated that presence of parasitaemia was significantly lower among those receiving MPPT than those who did not. Similarly, in a mass blood survey conducted in the study sites during May, 2002 involving 5138 persons in study and 4215 in comparison areas, the total positive results were 7-10 times rarer in the treatment group both before and after the malaria transmission season. In addition, the number of malaria cases in the MPPT treatment ris was strikingly lower than control ris in every month during the malaria transmission season of 2002. The prevalence of G6PDD deficiency in DPR Korea is low, haemolytic events are rare and deaths due to MPPT have not been reported. MPPT in itself is a powerful intervention and the decision to deploy it depends on the epidemiology of malaria, urgency of malaria control and resources available in the country.

  12. Quantitative extraction of Meiofauna: A comparison of two methods ...

    African Journals Online (AJOL)

    Two methods for the quantitative extraction of meiofauna from natural sandy sediments were investigated and compared: Cobb's decanting and sieving technique and the Oostenbrink elutriator. Both techniques were more efficient with pre-fixed samples than with fresh samples. The results indicated that elutriation is the ...

  13. Comparison between two methods for resin removing after bracket debonding

    Directory of Open Access Journals (Sweden)

    Rodrigo De Marchi

    2012-12-01

    Full Text Available OBJECTIVE: The aim of this study was to assess - using scanning electron microscopy (SEM - the effectiveness of two abrasive discs, one made from silicon and one from aluminum oxide, in removing adhesive remnants (AR after debonding orthodontic brackets. METHODS: Ten randomly selected bovine teeth were used, i.e., 2 in the control group, and the other 8 divided into two groups, which had orthodontic brackets bonded to their surface with Concise Orthodontic Adhesive (3M. The following methods were employed - in one single step - to remove AR after debracketing: Group A, Optimize discs (TDV and Group B, Onegloss discs (Shofu, used at low speed. After removing the AR with the aforementioned methods, the teeth were prepared to undergo SEM analysis, and photographs were taken of the enamel surface with 50x magnification. Six examiners evaluated the photographs applying the Zachrisson and Årtun enamel surface index (ESI system (1979. RESULTS: Group A exhibited minor scratches on the enamel surface as well as some AR in some of the photographs, while Group B showed a smoother surface, little or no AR and some abrasion marks in the photographs. No statistically significant differences were found between the two methods and the control group. CONCLUSIONS: The two abrasive discs were effective in removing the AR after bracket debonding in one single step.OBJETIVO: o objetivo deste trabalho foi avaliar, por microscopia eletrônica de varredura, a eficácia de dois discos abrasivos de silicone e óxido de alumínio para a remoção da resina remanescente após a descolagem de braquetes ortodônticos. MÉTODOS: foram utilizados 10 dentes bovinos selecionados aleatoriamente, sendo 2 para o grupo controle e os demais divididos em dois grupos, os quais receberam colagem de braquetes ortodônticos com resina ortodôntica Concise (3M. Os métodos de remoção da resina após a descolagem dos acessórios ortodônticos em apenas uma etapa foram: Grupo A - disco

  14. MODELLING AND CONTROL OF PARTIALLY SHADED PHOTOVOLTAIC ARRAYS

    Directory of Open Access Journals (Sweden)

    Chia Seet Chin

    2013-01-01

    Full Text Available The photovoltaic (PV array controlled by Maximum Power Point Tracking (MPPT method for optimum PV power generation, particularly when the PV array is under partially shaded condition is presented in this paper. The system modelling is carried out in MATLAB-SIMULINK where the PV array is formed by five series connected identical PV modules. Under uniform solar irradiance conditions, the PV module and the PV array present nonlinear P-V characteristic but the maximum power point (MPP can be easily identified. However, when the PV array is under shaded conditions, the P-V characteristic becomes more complex with the present of multiple MPP. While the PV array operated at local MPP, the generated power is limited. Thus, the investigation on MPPT approach is carried out to maximize the PV generated power even when the PV array is under partially shaded conditions (PSC. Fuzzy logic is adopted into the conventional MPPT to form fuzzy logic based MPPT (FMPPT for better performance. The developed MPPT and FMPPT are compared, particularly the performances on the transient response and the steady state response when the array is under various shaded conditions. FMPPT shows better performance where the simulation results demonstrate FMPPT is able to facilitate the PV array to reach the MPP faster while it helps the PV array to produce a more stable output power.

  15. Control strategy of grid-connected photovoltaic generation system based on GMPPT method

    Science.gov (United States)

    Wang, Zhongfeng; Zhang, Xuyang; Hu, Bo; Liu, Jun; Li, Ligang; Gu, Yongqiang; Zhou, Bowen

    2018-02-01

    There are multiple local maximum power points when photovoltaic (PV) array runs under partial shading condition (PSC).However, the traditional maximum power point tracking (MPPT) algorithm might be easily trapped in local maximum power points (MPPs) and cannot find the global maximum power point (GMPP). To solve such problem, a global maximum power point tracking method (GMPPT) is improved, combined with traditional MPPT method and particle swarm optimization (PSO) algorithm. Under different operating conditions of PV cells, different tracking algorithms are used. When the environment changes, the improved PSO algorithm is adopted to realize the global optimal search, and the variable step incremental conductance (INC) method is adopted to achieve MPPT in optimal local location. Based on the simulation model of the PV grid system built in Matlab/Simulink, comparative analysis of the tracking effect of MPPT by the proposed control algorithm and the traditional MPPT method under the uniform solar condition and PSC, validate the correctness, feasibility and effectiveness of the proposed control strategy.

  16. Efficiency of Photovoltaic Maximum Power Point Tracking Controller Based on a Fuzzy Logic

    Directory of Open Access Journals (Sweden)

    Ammar Al-Gizi

    2017-07-01

    Full Text Available This paper examines the efficiency of a fuzzy logic control (FLC based maximum power point tracking (MPPT of a photovoltaic (PV system under variable climate conditions and connected load requirements. The PV system including a PV module BP SX150S, buck-boost DC-DC converter, MPPT, and a resistive load is modeled and simulated using Matlab/Simulink package. In order to compare the performance of FLC-based MPPT controller with the conventional perturb and observe (P&O method at different irradiation (G, temperature (T and connected load (RL variations – rising time (tr, recovering time, total average power and MPPT efficiency topics are calculated. The simulation results show that the FLC-based MPPT method can quickly track the maximum power point (MPP of the PV module at the transient state and effectively eliminates the power oscillation around the MPP of the PV module at steady state, hence more average power can be extracted, in comparison with the conventional P&O method.

  17. Error analysis of two methods for range-images registration

    Science.gov (United States)

    Liu, Xiaoli; Yin, Yongkai; Li, Ameng; He, Dong; Peng, Xiang

    2010-08-01

    With the improvements in range image registration techniques, this paper focuses on error analysis of two registration methods being generally applied in industry metrology including the algorithm comparison, matching error, computing complexity and different application areas. One method is iterative closest points, by which beautiful matching results with little error can be achieved. However some limitations influence its application in automatic and fast metrology. The other method is based on landmarks. We also present a algorithm for registering multiple range-images with non-coding landmarks, including the landmarks' auto-identification and sub-pixel location, 3D rigid motion, point pattern matching, global iterative optimization techniques et al. The registering results by the two methods are illustrated and a thorough error analysis is performed.

  18. COMPARISON OF TWO METHODS FOR THE DETECTION OF LISTERIA MONOCYTOGENES

    Directory of Open Access Journals (Sweden)

    G. Tantillo

    2013-02-01

    Full Text Available The aim of this study was to compare the performance of the conventional methods for detection of Listeria monocytogenes in food using media Oxford and ALOA (Agar Listeria acc. to Ottaviani & Agosti in according to the ISO 11290-1 to a new chromogenic medium “CHROMagar Listeria” standardized in 2005 AFNOR ( CHR – 21/1-12/01. A total of 40 pre-packed ready-to-eat food samples were examined. Using two methods six samples were found positive for Listeria monocytogenes but the medium “CHROMagar Listeria” was more selective in comparison with the others. In conclusion this study has demonstrated that isolation medium able to target specifically the detection of L. monocytogenes such as “CHROMagar Listeria” is highly recommendable because of that detection time is significantly reduced and the analysis cost is less expensive.

  19. Comparison of two methods for glucocorticoid evaluation in maned wolves

    Directory of Open Access Journals (Sweden)

    Angélica S Vasconcellos

    2011-12-01

    Full Text Available Analysis of faecal glucocorticoid metabolites provides a powerful noninvasive tool for monitoring adrenocortical activity in wild animals. However, differences regarding the metabolism and excretion of these substances make a validation for each species and sex investigated obligatory. Although maned wolves (Chrysocyon brachyurus are the biggest canids in South America, their behaviour and physiology are poorly known and they are at risk in the wild. Two methods for measuring glucocorticoid metabolites in maned wolves were validated: a radio- and an enzyme immunoassay. An ACTH challenge was used to demonstrate that changes in adrenal function are reflected in faecal glucocorticoid metabolites. Our results suggest that both methods enable a reliable assessment of stress hormones in maned wolves avoiding short-term rises in glucocorticoid concentrations due to handling and restraint. These methods can be used as a valuable tool in studies of stress and conservation in this wild species.

  20. A Maximum Power Point Tracking Control Method of a Photovoltaic Power Generator with Consideration of Dynamic Characteristics of Solar Cells

    Science.gov (United States)

    Watanabe, Takashi; Yoshida, Toshiya; Ohniwa, Katsumi

    This paper discusses a new control strategy for photovoltaic power generation systems with consideration of dynamic characteristics of the photovoltaic cells. The controller estimates internal currents of an equivalent circuit for the cells. This estimated, or the virtual current and the actual voltage of the cells are fed to a conventional Maximum-Power-Point-Tracking (MPPT) controller. Consequently, this MPPT controller still tracks the optimum point even though it is so designed that the seeking speed of the operating point is extremely high. This system may suit for applications, which are installed in rapidly changeable insolation and temperature-conditions e.g. automobiles, trains, and airplanes. The proposed method is verified by experiment with a combination of this estimating function and the modified Boehringer's MPPT algorithm.

  1. Photovoltaic System Equipped with Digital Command Control and Acquisition

    Directory of Open Access Journals (Sweden)

    Khalil Kassmi

    2013-07-01

    Full Text Available In this paper, we present results concerning the design, the realization and the characterization of a photovoltaic system (PV, equipped with a digital controls: Power Point Tracking (MPPT, charge/discharge lead acid batteries, sun tracker and supervision. These different functions are performed with a microcontroller that has capabilities and functions to the reliability of PV systems (signal generation Pulses Width Modulation (PWM, speed etc.. Concerning the MPPT control operation, we improved the accuracy and reliability of research by improving the search algorithm “Hill Climbing” taking into account the optimal operation of PV panels depending on weather conditions (temperature and light.The experiment of each block shows that the MPPT control converges instantly the operating point of the PV panels around the maximum power point, independently of sudden changes of the illumination or the load. The control blocks charge/discharge battery and sun tracking show good control of charge/discharge lead acid batteries and the need of sun tracker to increase the power supplied by the PV panel. By using the improved MPPT control, loss of power supplied by the PV panels are very low (below 5%.

  2. Modeling of Maximum Power Point Tracking Controller for Solar Power System

    Directory of Open Access Journals (Sweden)

    Aryuanto Soetedjo

    2012-09-01

    Full Text Available In this paper, a Maximum Power Point Tracking (MPPT controller for solar power system is modeled using MATLAB Simulink. The model consists of PV module, buck converter, and MPPT controller. The contribution of the work is in the modeling of buck converter that allowing the input voltage of the converter, i.e. output voltage of PV is changed by varying the duty cycle, so that the maximum power point could be tracked when the environmental changes. The simulation results show that the developed model performs well in tracking the maximum power point (MPP of the PV module using Perturb and Observe (P&O Algorithm.

  3. Comparative examination of two methods for modeling autoimmune uveitis

    Directory of Open Access Journals (Sweden)

    Svetlana V. Aksenova

    2017-09-01

    Full Text Available Introduction: Uveitis is a disease of the uveal tract, characterized by a variety of causes and clinical manifestations. The internal antigens prevail often in the pathogenesis of the disease and develop the so-called autoimmune reactions. The uveitis treatment has an important medico-social significance because of the high prevalence of uveitis, the significant rate of the disease in young people, and high disability. The article compares the efficiency of two methods for modeling autoimmune uveitis. Materials and Methods: The research was conducted on 6 rabbits of the Chinchilla breed (12 eyes. Two models of experimental uveitis were reproduced on rabbits using normal horse serum during the research. A clinical examination of the inflammatory process course in the eyes was carried out by biomicroscopy using a slit lamp, and a direct ophthalmoscope. Histological and immunological examinations were conducted by the authors of the article. Results: The faster-reproducing and vivid clinical picture of the disease was observed in the second group. The obvious changes in the immunological status of the animals were noted also: an increase in the number of leukocytes, neutrophils, HCT-active neutrophils, and activation of phagocytosis. Discussion and Conclusions: The research has showed that the second model of uveitis is the most convenient working variant, which is characterized by high activity and duration of the inflammatory process in the eye.

  4. Comparing two methods of thoracoscopic sympathectomy for palmar hyperhidrosis.

    Science.gov (United States)

    Ibrahim, Magdi; Allam, Abdulla

    2014-09-01

    Hyperhidrosis can cause significant professional and social handicaps. Thoracic endoscopic sympathectomy has become the surgical technique of choice for treating intractable palmar hyperhidrosis and can be performed through multiple ports or a single port. This prospective study compares outcomes between the two methods. The study followed 71 consecutive patients who underwent video-assisted sympathectomy for palmar hyperhidrosis between January 2008 and June 2012. In all patients, the procedure was bilateral and performed in one stage. The multiple-port method was used in 35 patients (group A) and the single-port method in 36 patients (group B). Preoperative, intraoperative, and postoperative variables; morbidity, recurrence; and survival were compared in both groups. The procedure was successful in 100% of the patients; none experienced a recurrence of palmar hyperhidrosis, Horner syndrome (oculosympathetic palsy), or serious postoperative complications, and none died. No patients required conversion to an open procedure. Residual minimal pneumothorax occurred in two patients (5.7%) in group A and in one patient (2.8%) in group B. Minimal hemothorax occurred in one patient (2.9%) in group A and in three patients (8.3%) in group B. Compensatory hyperhidrosis occurred in seven patients (20%) in group A and in eight patients (22.2%) in group B. No difference was found between the multiple- and single-port methods. Both are effective, safe minimally invasive procedures that permanently improve quality of life in patients with palmar hyperhidrosis.

  5. Soybean phospholipase D activity determination. A comparison of two methods

    Directory of Open Access Journals (Sweden)

    Ré, E.

    2007-09-01

    Full Text Available Due to a discrepancy between previously published results, two methods to determine the soybean phospholipase D activity were evaluated. One method is based on the extraction of the enzyme from whole soybean flour, quantifying the enzyme activity on the extract. The other method quantifies the enzymatic activity on whole soybean flour without enzyme extraction. In the extraction-based-method, both the extraction time and the number of extractions were optimized. The highest phospholipase D activity values were obtained from the method without enzyme extraction. This method is less complex, requires less running-time and the conditions of the medium in which phospholipase D acts resemble the conditions found in the oil industrySe evaluaron dos métodos para determinar la actividad de la fosfolipasa D en soja debido a que existe discrepancia entre los resultados publicados. Un método se basa en la extracción de la enzima de la harina resultante de la molienda del grano de soja entero, cuantificando la actividad sobre el extracto. En el otro método, la cuantificación se realiza sobre la harina del grano entero molido, sin extraer la enzima. En el método de extracción se optimizaron tanto el tiempo como el número de extracciones. Los mayores valores de actividad de la fosfolipasa D se obtuvieron por el método sin extracción de la enzima. Este método es más simple, exige menos tiempo de ejecución y las condiciones del medio en que actúa la fosfolipasa D se asemejan a las condiciones encontradas en la industria aceitera.

  6. Power Smoothing and MPPT for Grid-connected Wind Power Generation with Doubly Fed Induction Generator

    Science.gov (United States)

    Kai, Takaaki; Tanaka, Yuji; Kaneda, Hirotoshi; Kobayashi, Daichi; Tanaka, Akio

    Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation, and variable speed control and power factor control are executed for high efficiently for wind energy capture and high quality for power system voltage. In variable speed control, a wind speed or a generator speed is used for maximum power point tracking. However, performances of a wind generation power fluctuation due to wind speed variation have not yet investigated for those controls. The authors discuss power smoothing by those controls for the DFIG inter-connected to 6.6kV distribution line. The performances are verified using power system simulation software PSCAD/EMTDC for actual wind speed data and are examined from an approximate equation of wind generation power fluctuation for wind speed variation.

  7. Maximum Energy Output of a DFIG Wind Turbine Using an Improved MPPT-Curve Method

    Directory of Open Access Journals (Sweden)

    Dinh-Chung Phan

    2015-10-01

    Full Text Available A new method is proposed for obtaining the maximum power output of a doubly-fed induction generator (DFIG wind turbine to control the rotor- and grid-side converters. The efficiency of maximum power point tracking that is obtained by the proposed method is theoretically guaranteed under assumptions that represent physical conditions. Several control parameters may be adjusted to ensure the quality of control performance. In particular, a DFIG state-space model and a control technique based on the Lyapunov function are adopted to derive the control method. The effectiveness of the proposed method is verified via numerical simulations of a 1.5-MW DFIG wind turbine using MATLAB/Simulink. The simulation results show that when the proposed method is used, the wind turbine is capable of properly tracking the optimal operation point; furthermore, the generator’s available energy output is higher when the proposed method is used than it is when the conventional method is used instead.

  8. Research Survey on Various MPPT Performance Issues to Improve the Solar PV System Efficiency

    Directory of Open Access Journals (Sweden)

    B. Pakkiraiah

    2016-01-01

    Full Text Available Nowadays in order to meet the increase in power demands and to reduce the global warming, renewable energy sources based system is used. Out of the various renewable energy sources, solar energy is the main alternative. But, compared to other sources, the solar panel system converts only 30–40% of solar irradiation into electrical energy. In order to get maximum output from a PV panel system, an extensive research has been underway for long time so as to access the performance of PV system and to investigate the various issues related to the use of solar PV system effectively. This paper therefore presents different types of PV panel systems, maximum power point tracking control algorithms, power electronic converters usage with control aspects, various controllers, filters to reduce harmonic content, and usage of battery system for PV system. Attempts have been made to highlight the current and future issues involved in the development of PV system with improved performance. A list of 185 research publications on this is appended for reference.

  9. Intelligent approach to maximum power point tracking control strategy for variable-speed wind turbine generation system

    Energy Technology Data Exchange (ETDEWEB)

    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)

  10. Maximum power point tracking-based control algorithm for PMSG wind generation system without mechanical sensors

    International Nuclear Information System (INIS)

    Hong, Chih-Ming; Chen, Chiung-Hsing; Tu, Chia-Sheng

    2013-01-01

    Highlights: ► This paper presents MPPT based control for optimal wind energy capture using RBFN. ► MPSO is adopted to adjust the learning rates to improve the learning capability. ► This technique can maintain the system stability and reach the desired performance. ► The EMF in the rotating reference frame is utilized in order to estimate speed. - Abstract: This paper presents maximum-power-point-tracking (MPPT) based control algorithms for optimal wind energy capture using radial basis function network (RBFN) and a proposed torque observer MPPT algorithm. The design of a high-performance on-line training RBFN using back-propagation learning algorithm with modified particle swarm optimization (MPSO) regulating controller for the sensorless control of a permanent magnet synchronous generator (PMSG). The MPSO is adopted in this study to adapt the learning rates in the back-propagation process of the RBFN to improve the learning capability. The PMSG is controlled by the loss-minimization control with MPPT below the base speed, which corresponds to low and high wind speed, and the maximum energy can be captured from the wind. Then the observed disturbance torque is feed-forward to increase the robustness of the PMSG system

  11. Assessment of MPPT Techniques During the Faulty Conditions of PV System

    Directory of Open Access Journals (Sweden)

    Bhukya Krishna Naick

    2018-01-01

    Full Text Available The contribution of Distributed Generation (DG systems like wind energy systems and solar Photovoltaic (PV systems on the generation of electricity has increased. Out of these DG systems, the PV systems have gained wide popularity, because of the availability of solar energy throughout the day. Depending on the size of PV installations, a large number of PV modules can be interconnected in the form of series and parallel connection. Since a large number of modules are interconnected, it is possible for the faults in a PV array to occur due to the failure of protection system, which can cause damage to the PV module and also the decrease in the output power. This paper presents the tracking of a maximum power point under the faulty conditions of 12x5 PV array. The fault conditions that have been considered in the PV array are open circuit fault, line to ground, line to line and failure of bypass diodes. Perturb and observe, incremental conductance and fuzzy logic controller are the maximum power point tracking techniques that have been implemented. For each of the fault conditions, the results have been presented in terms of the maximum power tracked, tracking time and tracking efficiency.

  12. Control Strategy of Two Capacitor Voltages for Separate MPPTs in Photovoltaic Systems Using Neutral-Point-Clamped Inverters

    DEFF Research Database (Denmark)

    Choi, Ui-Min; Blaabjerg, Frede; Lee, Kyo-Beum

    2015-01-01

    and panel mismatch conditions. In this system, if PV modules are separately connected to the split capacitor voltage, the MPPT efficiency can be improved by the proposed control strategy. By the proposed method, the two capacitor voltages can be controlled asymmetrically to perform the separate MPPTs...

  13. Maximum Energy Extraction Control for Wind Power Generation Systems Based on the Fuzzy Controller

    Science.gov (United States)

    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.

  14. A Study of a Two Stage Maximum Power Point Tracking Control of a Photovoltaic System under Partially Shaded Insolation Conditions

    Science.gov (United States)

    Kobayashi, Kenji; Takano, Ichiro; Sawada, Yoshio

    A photovoltaic array shows relatively low output power density, and has a greatly drooping Current-Voltage (I-V) characteristic. Therefore, Maximum Power Point Tracking (MPPT) control is used to maximize the output power of the array. Many papers have been reported in relation to MPPT. However, the Current-Power (I-P) curve sometimes shows multi-local maximum points mode under non-uniform insolation conditions. The operating point of the PV system tends to converge to a local maximum output point which is not the real maximal output point on the I-P curve. Some papers have been also reported, trying to avoid this difficulty. However most of those control systems become rather complicated. Then, the two stage MPPT control method is proposed in this paper to realize a relatively simple control system which can track the real maximum power point even under non-uniform insolation conditions. The feasibility of this control concept is confirmed for steady insolation as well as for rapidly changing insolation by simulation study using software PSIM and LabVIEW. In addition, simulated experiment confirms fundament al operation of the two stage MPPT control.

  15. Sliding mode controller for a photovoltaic pumping system

    Science.gov (United States)

    ElOugli, A.; Miqoi, S.; Boutouba, M.; Tidhaf, B.

    2017-03-01

    In this paper, a sliding mode control scheme (SMC) for maximum power point tracking controller for a photovoltaic pumping system, is proposed. The main goal is to maximize the flow rate for a water pump, by forcing the photovoltaic system to operate in its MPP, to obtain the maximum power that a PV system can deliver.And this, through the intermediary of a sliding mode controller to track and control the MPP by overcoming the power oscillation around the operating point, which appears in most implemented MPPT techniques. The sliding mode control approach is recognized as one of the efficient and powerful tools for nonlinear systems under uncertainty conditions.The proposed controller with photovoltaic pumping system is designed and simulated using MATLAB/SIMULINK environment. In addition, to evaluate its performances, a classical MPPT algorithm using perturb and observe (P&O) has been used for the same system to compare to our controller. Simulation results are shown.

  16. Comparison of Sliding Mode Control and Fuzzy Logic control applied to Variable Speed Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Souhila Rached Zine

    2015-08-01

    Full Text Available wind energy features prominently as a supplementary energy booster. It does not pollute and is inexhaustible. However, its high cost is a major constraint, especially on the less windy sites. The purpose of wind energy systems is to maximize energy efficiency, and extract maximum power from the wind speed. In This case, the MPPT control becomes important. To realize this control, strategy conventional Proportional and Integral (PI controller is usually used. However, this strategy cannot achieve better performance. This paper proposes other control methods of a turbine which optimizes its production such as fuzzy logic, sliding mode control. These methods improve the quality and energy efficiency. The proposed Sliding Mode Control (SMC strategy and the fuzzy controllers have presented attractive features such as robustness to parametric uncertainties of the turbine, simplicity of its design and good performances. The simulation result under Matlab\\Simulink has validated the performance of the proposed MPPT strategies.

  17. Independent control strategy of two DC-link voltages for separate MPPTs in transformerless photovoltaic systems using neutral-point-clamped inverters

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede; Lee, Kyo-Beum

    2014-01-01

    To improve the efficiency of the photovoltaic (PV) system, the centralized topology using three-level inverters are widely used. In this system, PV modules are separately connected to the split DC-links. This causes a decrease of maximum power point tracking (MPPT) efficiency under the partial...... shading condition. This paper proposes an independent control of two DC-link voltages for separate MPPT of each PV module in three-level inverters. The proposed method is simply implemented by adding or subtracting the time-offset to the three-phase turn-on times and modifying the reference voltages...

  18. Comparison of nursing students’ Satisfaction about two methods of demonstration and simulation for training of mask making against chemical attacks

    Directory of Open Access Journals (Sweden)

    Monireh Ebadi

    2016-04-01

    Conclusion: there was no significant difference between the satisfaction for two methods of demonstration and simulation but researchers suggest that simulation method can be used for mask making training against chemical attacks as they believe that this method is the best way to promote military nurses ’education and control disaster situations.

  19. Two methods to simulate intrapulpal pressure: effects upon bonding performance of self-etch adhesives.

    Science.gov (United States)

    Feitosa, V P; Gotti, V B; Grohmann, C V; Abuná, G; Correr-Sobrinho, L; Sinhoreti, M A C; Correr, A B

    2014-09-01

    To evaluate the effects of two methods to simulate physiological pulpal pressure on the dentine bonding performance of two all-in-one adhesives and a two-step self-etch silorane-based adhesive by means of microtensile bond strength (μTBS) and nanoleakage surveys. The self-etch adhesives [G-Bond Plus (GB), Adper Easy Bond (EB) and silorane adhesive (SIL)] were applied to flat deep dentine surfaces from extracted human molars. The restorations were constructed using resin composites Filtek Silorane or Filtek Z350 (3M ESPE). After 24 h using the two methods of simulated pulpal pressure or no pulpal pressure (control groups), the bonded teeth were cut into specimens and submitted to μTBS and silver uptake examination. Results were analysed with two-way anova and Tukey's test (P self-etch adhesives had acceptable resistance against pulpal pressure, unlike the HEMA-rich adhesive. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  20. Rotor Speed Control of a Direct-Driven Permanent Magnet Synchronous Generator-Based Wind Turbine Using Phase-Lag Compensators to Optimize Wind Power Extraction

    Directory of Open Access Journals (Sweden)

    Ester Hamatwi

    2017-01-01

    Full Text Available Due to the intermittent nature of wind, the wind power output tends to be inconsistent, and hence maximum power point tracking (MPPT is usually employed to optimize the power extracted from the wind resource at a wide range of wind speeds. This paper deals with the rotor speed control of a 2 MW direct-driven permanent magnet synchronous generator (PMSG to achieve MPPT. The proportional-integral (PI, proportional-derivative (PD, and proportional-integral-derivative (PID controllers have widely been employed in MPPT studies owing to their simple structure and simple design procedure. However, there are a number of shortcomings associated with these controllers; the trial-and-error design procedure used to determine the P, I, and D gains presents a possibility for poorly tuned controller gains, which reduces the accuracy and the dynamic performance of the entire control system. Moreover, these controllers’ linear nature, constricted operating range, and their sensitivity to changes in machine parameters make them ineffective when applied to nonlinear and uncertain systems. On the other hand, phase-lag compensators are associated with a design procedure that is well defined from fundamental principles as opposed to the aforementioned trial-and-error design procedure. This makes the latter controller type more accurate, although it is not well developed yet, and hence it is the focus of this paper. The simulation results demonstrated the effectiveness of the proposed MPPT controller.

  1. Control of power sourced from a microbial fuel cell reduces its start-up time and increases bioelectrochemical activity.

    Science.gov (United States)

    Boghani, Hitesh C; Kim, Jung Rae; Dinsdale, Richard M; Guwy, Alan J; Premier, Giuliano C

    2013-07-01

    Microbial fuel cell (MFC) performance depends on the selective development of an electrogenic biofilm at an electrode. Controlled biofilm enrichment may reduce start-up time and improve subsequent power performance. The anode potential is known to affect start-up and subsequent performance in electrogenic bio-catalytic consortia. Control strategies varying electrical load through gradient based maximum power point tracking (MPPT) and transient poised anode potential followed by MPPT are compared to static ohmic loading. Three replicate H-type MFCs were used to investigate start-up strategies: (1) application of an MPPT algorithm preceded by poised-potential at the anode (+0.645 V vs Ag/AgCl); (2) MFC connected to MPPT-only; (3) static external load of 1 kΩ and 500 Ω. Active control showed a significant reduction in start-up time from 42 to 22 days, along with 3.5-fold increase in biocatalytic activity after start-up. Such active control may improve applicability by accelerating start-up and enhancing MFC power and bio-catalytic performance. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Grid-connected of photovoltaic module using nonlinear control

    DEFF Research Database (Denmark)

    El Fadil, H.; Giri, F.; Guerrero, Josep M.

    2012-01-01

    The problem of controlling single-phase grid connected photovoltaic (PV) system is considered. The control objective is fourfold: (i) asymptotic stability of the closed loop system, (ii) maximum power point tracking (MPPT) of PV module (iii) tight regulation of the DC bus voltage, and (iv) unity......, for the nonlinear characteristic of PV panel. It is formally shown, through theoretical analysis and simulation results, that the proposed controller does achieve its objectives....

  3. Model Predictive Control of Three Phase Inverter for PV Systems

    OpenAIRE

    Irtaza M. Syed; Kaamran Raahemifar

    2015-01-01

    This paper presents a model predictive control (MPC) of a utility interactive three phase inverter (TPI) for a photovoltaic (PV) system at commercial level. The proposed model uses phase locked loop (PLL) to synchronize the TPI with the power electric grid (PEG) and performs MPC control in a dq reference frame. TPI model consists of a boost converter (BC), maximum power point tracking (MPPT) control, and a three-leg voltage source inverter (VSI). The operational model of ...

  4. Comparative studies of two methods for miRNA isolation from milk whey*

    Science.gov (United States)

    Jin, Xiao-lu; Wei, Zi-hai; Liu, Lan; Liu, Hong-yun; Liu, Jian-xin

    2015-01-01

    MicroRNAs (miRNAs) from milk whey have been considered for their potential as noninvasive biomarkers for milk quality control and disease diagnosis. However, standard protocols for miRNA isolation and quantification from milk whey are not well established. The objective of this study was to compare two methods for the isolation of miRNAs from milk whey. These two methods were modified phenol-based technique (Trizol LS® followed by phenol precipitation, the TP method) and combined phenol and column-based approach (Trizol LS® followed by cleanup using the miRNeasy kit, the TM method). Yield and quality of RNA were rigorously measured using a NanoDrop ND-1000 spectrophotometer and then the distribution of RNA was precisely detected in a Bioanalyzer 2100 instrument by microchip gel electrophoresis. Several endogenous miRNAs (bta-miR-141, bta-miR-146a, bta-miR-148a, bta-miR-200c, bta-miR-362, and bta-miR-375) and an exogenous spike-in synthetic control miRNA (cel-miR-39) were quantified by real-time polymerase chain reaction (PCR) to examine the apparent recovery efficiency of milk whey miRNAs. Both methods could successfully isolate sufficient small RNA (whey, and their yields were quite similar. However, the quantification results show that the total miRNA recovery efficiency by the TM method is superior to that by the TP method. The TM method performed better than the TP for recovery of milk whey miRNA due to its consistency and good repeatability in endogenous and spike-in miRNA recovery. Additionally, quantitative recovery analysis of a spike-in miRNA may be more accurate to reflect the milk whey miRNA recovery efficiency than using traditional RNA quality analysis instruments (NanoDrop or Bioanalyzer 2100). PMID:26055915

  5. Comparative studies of two methods for miRNA isolation from milk whey.

    Science.gov (United States)

    Jin, Xiao-lu; Wei, Zi-hai; Liu, Lan; Liu, Hong-yun; Liu, Jian-xin

    2015-06-01

    MicroRNAs (miRNAs) from milk whey have been considered for their potential as noninvasive biomarkers for milk quality control and disease diagnosis. However, standard protocols for miRNA isolation and quantification from milk whey are not well established. The objective of this study was to compare two methods for the isolation of miRNAs from milk whey. These two methods were modified phenol-based technique (Trizol LS(®) followed by phenol precipitation, the TP method) and combined phenol and column-based approach (Trizol LS(®) followed by cleanup using the miRNeasy kit, the TM method). Yield and quality of RNA were rigorously measured using a NanoDrop ND-1000 spectrophotometer and then the distribution of RNA was precisely detected in a Bioanalyzer 2100 instrument by microchip gel electrophoresis. Several endogenous miRNAs (bta-miR-141, bta-miR-146a, bta-miR-148a, bta-miR-200c, bta-miR-362, and bta-miR-375) and an exogenous spike-in synthetic control miRNA (cel-miR-39) were quantified by real-time polymerase chain reaction (PCR) to examine the apparent recovery efficiency of milk whey miRNAs. Both methods could successfully isolate sufficient small RNA (whey, and their yields were quite similar. However, the quantification results show that the total miRNA recovery efficiency by the TM method is superior to that by the TP method. The TM method performed better than the TP for recovery of milk whey miRNA due to its consistency and good repeatability in endogenous and spike-in miRNA recovery. Additionally, quantitative recovery analysis of a spike-in miRNA may be more accurate to reflect the milk whey miRNA recovery efficiency than using traditional RNA quality analysis instruments (NanoDrop or Bioanalyzer 2100).

  6. Flexible Power Control of Photovoltaic Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Sangwongwanich, Ariya; Yang, Yongheng

    2018-01-01

    With a still increasing penetration level of grid-connected photovoltaic (PV) systems, more advanced and flexible control functionalities are demanded. To ensure a smooth and friendly integration between the PV systems and the grid, the power generated by the PV system needs to be flexible...... the Maximum Power Point Tracking (MPPT) control algorithm of the power converter can realize the flexible power control requirement by regulating the operating point of the PV system below the maximum available power of the PV arrays. Therefore, this approach does not require an extra component, being a cost......-effective solution in terms of component cost and at the same time offering high reliability. The operational principle of the PV systems with the modifying MPPT algorithm is discussed in this chapter, where the flexible active power control functionalities are demonstrate via experiments on a two-stage grid...

  7. Maximum-power-point tracking control of solar heating system

    KAUST Repository

    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.

  8. Advanced Control Strategy of Back-to-Back PWM Converters in PMSG Wind Power System

    Directory of Open Access Journals (Sweden)

    Tan Luong Van

    2015-01-01

    Full Text Available This paper proposes a control scheme of back-to-back PWM converters for the permanent magnet synchronous generator (PMSG wind turbine system. The DC-link voltage can be controlled at the machine-side converter (MSC, while the grid-side converter (GSC controls the grid active power for a maximum power point tracking (MPPT. At the grid fault condition, the DC-link voltage controller is designed using a feedback linearization (FL theory. For the MPPT, a proportional control loop is added to the torque control to reduce the influence of the inertia moment in the wind turbines, which can improve its dynamic performance. The validity of this control algorithm has been verified by the simulation of the 2-MW PMSG wind turbine system.

  9. L1 Adaptive Speed Control of a Small Wind Energy Conversion System for Maximum Power Point Tracking

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Rasmussen, Claus Nygaard

    2014-01-01

    This paper presents the design of an L1 adaptive controller for maximum power point tracking (MPPT) of a small variable speed Wind Energy Conversion System (WECS). The proposed controller generates the optimal torque command for the vector controlled generator side converter (GSC) based on the wi......) is used to carry out case studies using Matlab/Simulink. The case study results show that the designed L1 adaptive controller has good tracking performance even with unmodeled dynamics and in the presence of parameter uncertainties and unknown disturbances.......This paper presents the design of an L1 adaptive controller for maximum power point tracking (MPPT) of a small variable speed Wind Energy Conversion System (WECS). The proposed controller generates the optimal torque command for the vector controlled generator side converter (GSC) based on the wind...

  10. Monitoring of Urinary Calcium and Phosphorus Excretion in Preterm Infants - Comparison of two Methods

    OpenAIRE

    Staub, Eveline; Wiedmer, Nicolas; Staub, Lukas P.; Nelle, Mathias; von Vigier, Rodo O.

    2014-01-01

    OBJECTIVES: Premature babies require supplementation with calcium and phosphorus to prevent metabolic bone disease of prematurity. To guide mineral supplementation, two methods of monitoring urinary excretion of calcium and phosphorus are used: urinary calcium or phosphorus concentration and calcium/creatinine or phosphorus/creatinine ratios. We compare these two methods in regards to their agreement on the need for mineral supplementation. METHODS: Retrospective chart review of 2...

  11. Dynamic Model and Control of a Photovoltaic Generation System using Energetic Macroscopic Representation

    Science.gov (United States)

    Solano, Javier; Duarte, José; Vargas, Erwin; Cabrera, Jhon; Jácome, Andrés; Botero, Mónica; Rey, Juan

    2016-10-01

    This paper addresses the Energetic Macroscopic Representation EMR, the modelling and the control of photovoltaic panel PVP generation systems for simulation purposes. The model of the PVP considers the variations on irradiance and temperature. A maximum power point tracking MPPT algorithm is considered to control the power converter. A novel EMR is proposed to consider the dynamic model of the PVP with variations in the irradiance and the temperature. The EMR is evaluated through simulations of a PVP generation system.

  12. A Control Method for Maximum Power Point Tracking in Stand-Alone-Type PV Generation Systems

    Science.gov (United States)

    Itako, Kazutaka; Mori, Takeaki

    In this paper, a new control method for maximum power point tracking (MPPT) in stand-alone-type PV generaton systems is proposed. In this control method, the operations detecting the maximum power point and tracking its point are alternately carried out by using a step-up DC—DC converter. This method requires neither the measurement of temperature and insolation level nor PV array model. In a stand-alone-type application with a battery load, the design method for the boost inductance L of the step-up DC—DC converter is described, and the experimental results show that the use of the proposed MPPT control increases the PV generated energy by 14.8% compared to the conventional system.

  13. Fuzzy logic, PSO based fuzzy logic algorithm and current controls comparative for grid-connected hybrid system

    Science.gov (United States)

    Borni, A.; Abdelkrim, T.; Zaghba, L.; Bouchakour, A.; Lakhdari, A.; Zarour, L.

    2017-02-01

    In this paper the model of a grid connected hybrid system is presented. The hybrid system includes a variable speed wind turbine controlled by aFuzzy MPPT control, and a photovoltaic generator controlled with PSO Fuzzy MPPT control to compensate the power fluctuations caused by the wind in a short and long term, the inverter currents injected to the grid is controlled by a decoupled PI current control. In the first phase, we start by modeling of the conversion system components; the wind system is consisted of a turbine coupled to a gearless permanent magnet generator (PMG), the AC/DC and DC-DC (Boost) converter are responsible to feed the electric energy produced by the PMG to the DC-link. The solar system consists of a photovoltaic generator (GPV) connected to a DC/DC boost converter controlled by a PSO fuzzy MPPT control to extract at any moment the maximum available power at the GPV terminals, the system is based on maximum utilization of both of sources because of their complementary. At the end. The active power reached to the DC-link is injected to the grid through a DC/AC inverter, this function is achieved by controlling the DC bus voltage to keep it constant and close to its reference value, The simulation studies have been performed using Matlab/Simulink. It can be concluded that a good control system performance can be achieved.

  14. Evaluation of two methods of predicting MLC leaf positions using EPID measurements

    International Nuclear Information System (INIS)

    Parent, Laure; Seco, Joao; Evans, Phil M.; Dance, David R.; Fielding, Andrew

    2006-01-01

    In intensity modulated radiation treatments (IMRT), the position of the field edges and the modulation within the beam are often achieved with a multileaf collimator (MLC). During the MLC calibration process, due to the finite accuracy of leaf position measurements, a systematic error may be introduced to leaf positions. Thereafter leaf positions of the MLC depend on the systematic error introduced on each leaf during MLC calibration and on the accuracy of the leaf position control system (random errors). This study presents and evaluates two methods to predict the systematic errors on the leaf positions introduced during the MLC calibration. The two presented methods are based on a series of electronic portal imaging device (EPID) measurements. A comparison with film measurements showed that the EPID could be used to measure leaf positions without introducing any bias. The first method, referred to as the 'central leaf method', is based on the method currently used at this center for MLC leaf calibration. It mimics the manner in which leaf calibration parameters are specified in the MLC control system and consequently is also used by other centers. The second method, a new method proposed by the authors and referred to as the ''individual leaf method,'' involves the measurement of two positions for each leaf (-5 and +15 cm) and the interpolation and extrapolation from these two points to any other given position. The central leaf method and the individual leaf method predicted leaf positions at prescribed positions of -11, 0, 5, and 10 cm within 2.3 and 1.0 mm, respectively, with a standard deviation (SD) of 0.3 and 0.2 mm, respectively. The individual leaf method provided a better prediction of the leaf positions than the central leaf method. Reproducibility tests for leaf positions of -5 and +15 cm were performed. The reproducibility was within 0.4 mm on the same day and 0.4 mm six weeks later (1 SD). Measurements at gantry angles of 0 deg., 90 deg., and 270 deg

  15. The effects of two methods of reflexology and stretching exercises on the severity of restless leg syndrome among hemodialysis patients

    Science.gov (United States)

    Shahgholian, Nahid; Jazi, Shahrzad Khojandi; Karimian, Jahangir; Valiani, Mahboubeh

    2016-01-01

    Background: Restless leg syndrome prevalence is high among the patients undergoing hemodialysis. Due to several side effects of medicational treatments, the patients prefer non-medicational methods. Therefore, the present study aimed to investigate the effects of two methods of reflexology and stretching exercises on the severity of restless leg syndrome among patients undergoing hemodialysis. Materials and Methods: This study is a randomized clinical trial that was done on 90 qualified patients undergoing hemodialysis in selected hospitals of Isfahan, who were diagnosed with restless leg syndrome through standard restless leg syndrome questionnaire. They were randomly assigned by random number table to three groups: Reflexology, stretching exercises, and control groups through random allocation. Foot reflexology and stretching exercises were conducted three times a week for 30–40 min within straight 4 weeks. Data analysis was performed by SPSS version 18 using descriptive and inferential statistical analyses [one-way analysis of variance (ANOVA), paired t-test, and least significant difference (LSD) post hoc test]. Results: There was a significant difference in the mean scores of restless leg syndrome severity between reflexology and stretching exercises groups, compared to control (P restless leg syndrome severity were significantly higher in reflexology and stretching exercises groups compared to the control group (P restless leg syndrome. These two methods of treatment are recommended to the patients. PMID:27186197

  16. A Comparison of Two Methods for Recruiting Children with an Intellectual Disability

    Science.gov (United States)

    Adams, Dawn; Handley, Louise; Heald, Mary; Simkiss, Doug; Jones, Alison; Walls, Emily; Oliver, Chris

    2017-01-01

    Background: Recruitment is a widely cited barrier of representative intellectual disability research, yet it is rarely studied. This study aims to document the rates of recruiting children with intellectual disabilities using two methods and discuss the impact of such methods on sample characteristics. Methods: Questionnaire completion rates are…

  17. Photovoltaic System Regulation Based on a PID Fuzzy Controller to Ensure a Fixed Settling Time

    Directory of Open Access Journals (Sweden)

    Paula A. Ortiz-Valencia

    2013-11-01

    Full Text Available The main objective of the controllers in photovoltaic systems (PV is to ensure the maximum extraction of the available power. Those controllers usually combine the action of a maximum power point tracking algorithm (MPPT with a voltage regulator, which has the function of rejecting disturbances at the panel terminals. Such controllers are commonly based on PI and PID structures, it requiring linearized models at an operating point. But, due to disturbances generated by the environment and the load, the operating point of the system changes drastically, which hinder to obtain the desired system performance. This paper proposes to regulate the PV system using a Fuzzy PID controller, which adapts to changes in solar irradiance and load oscillations. This characteristic guarantees a constant settling time, which is required to precisely define the period of the MPPT algorithm. In the case of classical linear controllers, the period of the MPPT algorithm is set to the worst case (longest period which generates additional power losses by slowing down the tracking of the optimal operating point. Therefore, the solution proposed in this paper improves the overall system efficiency. Finally, such a solution is validated through simulations in Matlab®.

  18. Genetically Optimization of an Asymmetrical Fuzzy Logic Based Photovoltaic Maximum Power Point Tracking Controller

    Directory of Open Access Journals (Sweden)

    AL-GIZI, A.

    2017-11-01

    Full Text Available This paper introduces a new fuzzy logic controller (FLC based photovoltaic (PV maximum power point tracking (MPPT optimized with the genetic algorithm (GA. Four FLCs with five and seven numbers of triangular (tri and generalized bell (g-bell membership functions (MFs are analyzed. The performances of the analyzed algorithms have been compared with the appropriate performances of the classical perturb and observe (P&O algorithm by using the following criteria: the rise time (tr, the tracking accuracy of the output power, and the energy yield. The results showed that the FL-based PV MPPT controller with seven triangular (7-tri MFs provides the best steady-state performances.

  19. EVALUATION OF THE DISINFECTION EFFECTIVENESS AT MEAT PROCESSING BY THE TWO METHODS

    Directory of Open Access Journals (Sweden)

    Simona Kunová,Miroslava Kačániová

    2015-06-01

    Full Text Available The aim of this article was the control of disinfection in selected meat processing-plant by two methods – swabbing method and The 3M™ Petrifilm™ plates. Samples were collected within three months (September, October, November 2014. Together 54 samples selected surfaces were collected. Each month six samples were collected using imprint method with Petrifilm plates on total count of microorganisms, 6 samples using imprint method with Petrifilm plates on the number of coliforms and 6 samples using sterile swab method. Samples were collected from the workbench, conveyor belt, cutting blades, meat grinder, wall and knife. Total viable counts (TVC and coliform bacteria (CB were determined in samples. The values of TVC in September obtained by swabbing method were higher than allowable limit in sample no. 1 (3.70×102 CFU.cm-2 and in sample no. 4 (3.35×101 KTJ.cm-2. The values of TVC obtained by Petrifilm plates were lower than 10 CFU.cm-2 in all samples. Values of CB obtained by Petrifilm plates were lower than 1 CFU.cm-2 in all samples, CB obtained by swabbing method was 1.6×101 CFU.cm-2 in sample no. 6. Values of TVC obtained in October by Petrifilm plates and also by swabbing method were higher than permissible limit (< 10 CFU.cm-2 in sample no. 2 and sample no. 4. Values of CB obtained by Petrifilm plates were lower than 1 CFU.cm-2 in all samples, CB obtained by swabbing method was 3,65×101 CFU.cm-2 in sample no. 3, value of CB obtained by swab method in sample no. 3 does not meet requirements of internal company standards. Values of TVC obtained in November by Petrifilm plates were lower than 10 CFU.cm-2 in all samples. TVC otained by swab method were 1,25×101 CFU.cm-2 in sample no. 3 and 3,25×101 CFU.cm-2 in sample no. 4. Samples were not in accordance with requirements of internal company standards. Values of CB obtained in November by Petrifilm plates and by swabbing method were after disinfection lower than 1 CFU.cm-2 in all

  20. Evaluation of two methods to determine glyphosate and AMPA in soils of Argentina

    Science.gov (United States)

    De Geronimo, Eduardo; Lorenzon, Claudio; Iwasita, Barbara; Faggioli, Valeria; Aparicio, Virginia; Costa, Jose Luis

    2017-04-01

    Argentine agricultural production is fundamentally based on a technological package combining no-tillage and the dependence of glyphosate applications to control weeds in transgenic crops (soybean, maize and cotton). Therefore, glyphosate is the most employed herbicide in the country, where 180 to 200 million liters are applied every year. Due to its widespread use, it is important to assess its impact on the environment and, therefore, reliable analytical methods are mandatory. Glyphosate molecule exhibits unique physical and chemical characteristics which difficult its quantification, especially in soils with high organic matter content, such as the central eastern Argentine soils, where strong interferences are normally observed. The objective of this work was to compare two methods for extraction and quantification of glyphosate and AMPA in samples of 8 representative soils of Argentina. The first analytical method (method 1) was based on the use of phosphate buffer as extracting solution and dichloromethane to minimize matrix organic content. In the second method (method 2), potassium hydroxide was used to extract the analytes followed by a clean-up step using solid phase extraction (SPE) to minimize strong interferences. Sensitivity, recoveries, matrix effects and robustness were evaluated. Both methodologies involved a derivatization with 9-fluorenyl-methyl-chloroformate (FMOC) in borate buffer and detection based on ultra-high-pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Recoveries obtained from soil samples spiked at 0.1 and 1 mg kg-1 and were satisfactory in both methods (70% - 120%). However, there was a remarkable difference regarding the matrix effect, being the SPE clean-up step (method 2) insufficient to remove the interferences. Whereas the dilution and the clean-up with dichloromethane (method 1) were more effective minimizing the ionic suppression. Moreover, method 1 had fewer steps in the protocol of sample

  1. Modeling and simulation performance of photovoltaic system integration battery and supercapacitor paralellization of MPPT prototipe for solar vehicle

    Science.gov (United States)

    Ajiatmo, Dwi; Robandi, Imam

    2017-03-01

    This paper proposes a control scheme photovoltaic, battery and super capacitor connected in parallel for use in a solar vehicle. Based on the features of battery charging, the control scheme consists of three modes, namely, mode dynamic irradian, constant load mode and constant voltage charging mode. The shift of the three modes can be realized by controlling the duty cycle of the mosffet Boost converter system. Meanwhile, the high voltage which is more suitable for the application can be obtained. Compared with normal charging method with parallel connected current limiting detention and charging method with dynamic irradian mode, constant load mode and constant voltage charging mode, the control scheme is proposed to shorten the charging time and increase the use of power generated from the PV array. From the simulation results and analysis conducted to determine the performance of the system in state transient and steady-state by using simulation software Matlab / Simulink. Response simulation results demonstrate the suitability of the proposed concept.

  2. Comparison between Two Methods to Calculate the Transition Matrix of Orbit Motion

    Directory of Open Access Journals (Sweden)

    Ana Paula Marins Chiaradia

    2012-01-01

    Full Text Available Two methods to evaluate the state transition matrix are implemented and analyzed to verify the computational cost and the accuracy of both methods. This evaluation represents one of the highest computational costs on the artificial satellite orbit determination task. The first method is an approximation of the Keplerian motion, providing an analytical solution which is then calculated numerically by solving Kepler's equation. The second one is a local numerical approximation that includes the effect of 2. The analysis is performed comparing these two methods with a reference generated by a numerical integrator. For small intervals of time (1 to 10 s and when one needs more accuracy, it is recommended to use the second method, since the CPU time does not excessively overload the computer during the orbit determination procedure. For larger intervals of time and when one expects more stability on the calculation, it is recommended to use the first method.

  3. Comparison of Two Methods of Noise Power Spectrum Determinations of Medical Radiography Systems

    Science.gov (United States)

    Hassan, Wan Muhamad Saridan Wan; Ahmed Darwish, Zeki

    2011-03-01

    Noise in medical images is recognized as an important factor that determines the image quality. Image noise is characterized by noise power spectrum (NPS). We compared two methods of NPS determination namely the methods of Wagner and Dobbins on Lanex Regular TMG screen-film system and Hologic Lorad Selenia full field digital mammography system, with the aim of choosing the better method to use. The methods differ in terms of various parametric choices and algorithm implementations. These parameters include the low pass filtering, low frequency filtering, windowing, smoothing, aperture correction, overlapping of region of interest (ROI), length of fast Fourier transform, ROI size, method of ROI normalization, and slice selection of the NPS. Overall, the two methods agreed to the practical value of noise power spectrum between 10-3-10-6 mm2 over spatial frequency range 0-10 mm-1.

  4. Two methods for calculating regional cerebral blood flow from emission computed tomography of inert gas concentrations

    DEFF Research Database (Denmark)

    Kanno, I; Lassen, N A

    1979-01-01

    Two methods are described for calculation of regional cerebral blood flow from completed tomographic data of radioactive inert gas distribution in a slice of brain tissue. It is assumed that the tomographic picture gives the average inert gas concentration in each pixel over data collection perio...... are implemented using synthetic data of xenon-133 emission computed tomography and some of the difficulties likely to be encountered in practice are stressed.......Two methods are described for calculation of regional cerebral blood flow from completed tomographic data of radioactive inert gas distribution in a slice of brain tissue. It is assumed that the tomographic picture gives the average inert gas concentration in each pixel over data collection periods...

  5. Comparison of two methods of performing the Thellier experiment. [paleomagnetic intensity determination

    Science.gov (United States)

    Levi, S.

    1975-01-01

    Two methods for performing the Thellier experiment on paleointensity determinations are compared. The first method is essentially that of Coe (1967) and the second is a slight modification of it. Prepared samples containing different species of magnetic particles are used, and both methods are always performed on the same sample. The study is designed to accent procedural differences between the two methods. It is shown that only the Coe method yields linear PNRM-PTRM (Partial ThermoRemanent Magnetization) plots for single domain and pseudo-single domain particles, because it maintains the symmetry between high-temperature VRM (Viscous Remanent Magnetization) and spontaneous decay, whereas for the modified Coe method the spontaneous decay is enhanced. For multidomain remanence, even the Coe method yields a nonlinear concave-up PNRM-PTRM plot. Paleointensity determinations employing only the ratio NRM/TRM provide no means of evaluating the reliability of the results.

  6. Comparing two methods of simulating mirco-scale viscous flows in a porous channel

    Science.gov (United States)

    Gao, Hui; Han, Jie; Jin, Yan; Wang, Lian-Ping

    2007-11-01

    Water flows in natural soil porous media are important to colloid-facilitated transport of contaminants and other phenomena with groundwater as the carrier. The 3D micro-scale flow is complicated due to the complex geometry. The transport and deposition of colloids in such flows are affected by several physical and chemical forces involved. In this talk, we first compare two methods of simulating viscous flows in both 2D and 3D channels filled with glass-bead particles. The first method is Physalis developed by Prosperetti's group, at Johns Hopkins, based on solving the Navier-Stokes equation using a combination of numerical solution and local analytical Stokes flow representation. The second method is a meso-scale approach by solving a lattice Boltzmann equation. Specific implementation issues will be discussed. The two methods yield almost identical flows. Preliminary simulation results as well as parallel experimental results on colloid deposition in the porous channel will also be presented.

  7. Comparison of two methods of radiopharmaceuticals production and evaluation of their quality

    International Nuclear Information System (INIS)

    Portillo L, M.C.; Rodriguez J, S.

    1987-05-01

    Two methods for the following five radiopharmaceuticals production were compared: sulfur colloid, diethylenetriamine pentaacetic calcium salt, phyrophosphate sodium, albumin aggregated, glucoheptonate calcium salt. Radiochemical purity was determined by electrophoresis, thin-layer chromatography and bio-distribution test in mice and rats. It was concluded that chromatographic method shows better efficiency and that bio-distribution test should be done only when testing new radiopharmaceuticals because the good correlation of this test with thin-layer chromatography. (author)

  8. A comparison of two methods of logMAR visual acuity data scoring for statistical analysis

    Directory of Open Access Journals (Sweden)

    O. A. Oduntan

    2009-12-01

    Full Text Available The purpose of this study was to compare two methods of logMAR visual acuity (VA scoring. The two methods are referred to as letter scoring (method 1 and line scoring (method 2. The two methods were applied to VA data obtained from one hundred and forty (N=140 children with oculocutaneous albinism. Descriptive, correlation andregression statistics were then used to analyze the data.  Also, where applicable, the Bland and Altman analysis was used to compare sets of data from the two methods.  The right and left eyes data were included in the study, but because the findings were similar in both eyes, only the results for the right eyes are presented in this paper.  For method 1, the mean unaided VA (mean UAOD1 = 0.39 ±0.15 logMAR. The mean aided (mean ADOD1 VA = 0.50 ± 0.16 logMAR.  For method 2, the mean unaided (mean UAOD2 VA = 0.71 ± 0.15 logMAR, while the mean aided VA (mean ADOD2 = 0.60 ± 0.16 logMAR. The range and mean values of the improvement in VA for both methods were the same. The unaided VAs (UAOD1, UAOD2 and aided (ADOD1, ADOD2 for methods 1 and 2 correlated negatively (Unaided, r = –1, p<0.05, (Aided, r = –1, p<0.05.  The improvement in VA (differences between the unaided and aided VA values (DOD1 and DOD2 were positively correlated (r = +1, p <0.05. The Bland and Altman analyses showed that the VA improvement (unaided – aided VA values (DOD1 and DOD2 were similar for the two methods. Findings indicated that only the improvement in VA could be compared when different scoring methods are used. Therefore the scoring method used in any VA research project should be stated in the publication so that appropriate comparisons could be made by other researchers.

  9. Neural Network Based Maximum Power Point Tracking Control with Quadratic Boost Converter for PMSG—Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Ramji Tiwari

    2018-02-01

    Full Text Available This paper proposes an artificial neural network (ANN based maximum power point tracking (MPPT control strategy for wind energy conversion system (WECS implemented with a DC/DC converter. The proposed topology utilizes a radial basis function network (RBFN based neural network control strategy to extract the maximum available power from the wind velocity. The results are compared with a classical Perturb and Observe (P&O method and Back propagation network (BPN method. In order to achieve a high voltage rating, the system is implemented with a quadratic boost converter and the performance of the converter is validated with a boost and single ended primary inductance converter (SEPIC. The performance of the MPPT technique along with a DC/DC converter is demonstrated using MATLAB/Simulink.

  10. XAFS analysis of unsupported $MoS_{2}$ catalysts prepared by two methods

    CERN Document Server

    Matsubayashi, N; Imamura, M; Yoshimura, Y; Nishijima, A; Calais, C; Geantet, C

    1999-01-01

    Structural analysis by XAFS method was applied to two kinds of unsupported molybdenum disulfide catalysts. Assuming a structural model consisting of crystalline and non-crystalline parts, curve fitting analysis was performed for the $9 catalysts. The residual XAFS after subtraction of the crystalline contribution showed that the structure of the non-crystalline part was significantly different between the catalysts prepared by the two methods. It was suggested that $9 EXAFS would give the average size of the micro-domains, while other methods such as TEM and TPR would give the size of macro- domains. (6 refs).

  11. Comparison of Two Methods for Estimation of Work Limitation Scores from Health Status Measures

    DEFF Research Database (Denmark)

    Anatchkova, M; Fang, H; Kini, N

    2015-01-01

    future data collection strategies. Methods We used data from two independent cross-sectional panel samples (Sample1, n=1382, 51% female, 72% Caucasian, 49% with preselected chronic conditions, 15% with fair/poor health; Sample2, n=301, 45% female, 90% Caucasian, 47% with preselected chronic conditions......, 21% with fair/poor health). Method 1 used previously developed and validated IRT based calibration tables. Method 2 used regression models to develop aggregate imputation weights as described in the literature. We evaluated the agreement of observed and estimated WLQ scale scores from the two methods...

  12. Comparison of two methods to determine fan performance curves using computational fluid dynamics

    Science.gov (United States)

    Onma, Patinya; Chantrasmi, Tonkid

    2018-01-01

    This work investigates a systematic numerical approach that employs Computational Fluid Dynamics (CFD) to obtain performance curves of a backward-curved centrifugal fan. Generating the performance curves requires a number of three-dimensional simulations with varying system loads at a fixed rotational speed. Two methods were used and their results compared to experimental data. The first method incrementally changes the mass flow late through the inlet boundary condition while the second method utilizes a series of meshes representing the physical damper blade at various angles. The generated performance curves from both methods are compared with an experiment setup in accordance with the AMCA fan performance testing standard.

  13. A New Fractional-Order Based Intelligent Maximum Power Point Tracking Control Algorithm for Photovoltaic Power Systems

    OpenAIRE

    Yu, Kuo-Nan; Liao, Chih-Kang; Yau, Her-Terng

    2015-01-01

    This paper proposes a new type of variable fractional-order incremental conductance algorithm (VFOINC), combined with extenics variable step size (EVSS) control into the maximum power point tracking (MPPT) design for photovoltaic power systems. At the beginning of maximum power tracking, the fractional-order number α is selected as 1; the good transient tracking characteristic of traditional incremental conductance method is used. When the maximum power point is approached, the fractional-ord...

  14. [Estimating the frequency of induced abortion: a comparison of two methods].

    Science.gov (United States)

    Olinto, Maria Teresa Anselmo; Moreira Filho, Djalma de Carvalho

    2004-05-01

    To compare two methods-the "ballot box" method and the "indirect questioning" method-for estimating the frequency of induced abortions in population-based studies. A cross-sectional population-based study was conducted with a representative sample of 3 002 women between 15 and 49 years of age living in the city of Pelotas, Rio Grande do Sul, Brazil. The women were selected through multistage sampling and randomly assigned to answer questions concerning induced abortion with one of the two methods, after they had answered a general questionnaire that collected socioeconomic and demographic information. With the "ballot box" method, women received a small piece of paper containing direct questions on abortion. Each woman marked her answers on the paper and then deposited it into a small "ballot box" carried by the interviewer, thus assuring the confidentiality of the responses. With the second method, the interviewer verbally asked the woman a series of questions that indirectly inquired about abortion. Among the women assigned to the ballot box method, 7.2% reported having induced at least one abortion, versus 3.8% of the women assigned to the indirect questioning method. The ratio between the two methods was 1.89 (95% confidence interval: 1.39 to 2.60; P abortion in their lifetime. Among the women who answered using the ballot box method, the main reasons they gave for having had an abortion were economic difficulties, being too young, and being single. Approximately half of the women responding to the ballot box method questions reported they had used unsafe procedures to induce abortion, with 13% of them using misoprostol. The ballot box method was suitable for studying the frequency of induced abortion and for researching other topics that may lead to underreporting by the persons interviewed, especially in population-based samples. Rephrasing the ballot box method question about abortion (for example, eliminating the word "child") would probably increase the

  15. A New Fractional-Order Based Intelligent Maximum Power Point Tracking Control Algorithm for Photovoltaic Power Systems

    Directory of Open Access Journals (Sweden)

    Kuo-Nan Yu

    2015-01-01

    Full Text Available This paper proposes a new type of variable fractional-order incremental conductance algorithm (VFOINC, combined with extenics variable step size (EVSS control into the maximum power point tracking (MPPT design for photovoltaic power systems. At the beginning of maximum power tracking, the fractional-order number α is selected as 1; the good transient tracking characteristic of traditional incremental conductance method is used. When the maximum power point is approached, the fractional-order number α is selected as variable fractional order; the curve profile of α in fractional order is used to approximate, so that the system has good tracking effect in transient and steady states. The experimental and simulation results show that, compared with traditional incremental conductance method (INC and fractional-order incremental conductance method (FOINC, this method has better MPPT effect.

  16. A comparison of two methods to measure choroidal thickness by enhanced depth imaging optical coherence tomography

    DEFF Research Database (Denmark)

    Lundberg, Lars Kristian; Vestergaard, Anders Højslet; Vergmann, Anna Stage

    for mean intergrader ICC were 0.97 ±0.027 and 0.95 ±0.03 (P=0.17). A shorter mean time was found for the Segmentation method (7.3 ±1.6 minutes vs. 9.0 ±1.8 minutes, Pmethods from the inbuilt Heidelberg Eye Explorer software were suitable for manual measurement of the CT and showed...... coherence tomography (EDI-SD OCT) has made it possible to visualize the choroid, and it is generally accepted that Heidelberg Spectralis OCT provides valid measurements of choroidal thickness (CT), although no fully automated software is commercially available. Two methods for CT-measurement are available...... in the Heidelberg software, but to our knowledge these have not been compared. Hence, the purpose of this study was to evaluate and validate the Segmentation method and the Ruler method for CT-measurement. Methods We used the Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany) to record EDI...

  17. Comparative evaluation of two methods for 172Tm production in nuclear reactors

    International Nuclear Information System (INIS)

    Cohen, I.M.; Hayes, Alejandro; Melcer, Elsa

    2016-01-01

    A comparative evaluation of two methods for the production of 172 Tm in nuclear reactors is carried out. They are respectively based on two chains of double neutron capture reactions, 170 Er(n,γ) 171 Er(n,γ) 172 Er(β - ) 172 Tm and 170 Er(n,γ) 171 Er(β - ) 171 Tm(n,γ) 172 Tm, and a chain of triple neutron capture: 169 Tm(n,γ) 170 Tm(n,γ) 71 Tm(n,γ) 172 Tm. Theoretical considerations with respect to both ways of production are formulated and the mathematical equation are solved. Experiments of irradiation of Er 2 O 3 and Tm 2 O 3 were performed. Advantages and drawbacks of both methods are discussed. (author)

  18. Comparison of Two Methods for Evaluation of the Image Quality of Lumbar Spine Radiographs

    International Nuclear Information System (INIS)

    Tingberg, A.; Herrmann, C.; Lanhede, B.; Almn, A.; Besjakov, J.; Mattsson, S.; Sund, P.; Kheddache, S.; Maasson, L.G.

    2000-01-01

    Two methods for visual evaluation of image quality of clinical radiographs have been compared. In visual grading analysis (VGA) specified anatomical structures in an image are visually compared with the same structures in a reference image, and in a free-response forced error (FFE) experiment - an extension of conventional ROC (receiver operating characteristics) analysis - the objective is to localise known lesions correctly. The spatial resolution and noise of digitised clinical radiographs of the lumbar spine were altered by image processing, and pathological structures were added to the images for the FFE experiment. The images were printed to film and evaluated by seven European expert radiologists using VGA and FFE. The results of these two different methods showed a very good agreement. VGA methodology can be made as solid as the FFE experiment for evaluating image quality. The simplicity of VGA makes it very suitable for implementation in clinical practice. (author)

  19. Intracellular oxygen: Similar results from two methods of measurement using phosphorescent nanoparticles

    Directory of Open Access Journals (Sweden)

    David Lloyd

    2014-03-01

    Full Text Available The ability to resolve the spatio-temporal complexity of intracellular O2 distribution is the "Holy Grail" of cellular physiology. In an effort to obtain a minimally invasive approach to the mapping of intracellular O2 tensions, two methods of phosphorescent lifetime imaging microscopy were compared in the current study and gave similar results. These were two-photon confocal laser scanning microscopy with pinhole shifting, and picosecond time-resolved epi-phosphorescence microscopy using a single 0.5 μm focused spot. Both methods utilized Ru coordination complex embedded nanoparticles (45 nm diameter as the phosphorescent probe, excited using pulsed outputs of a titanium–sapphire Tsunami lasers (710–1050 nm.

  20. Supervisory Control of an Adaptive-Droop Regulated DC Microgrid with Battery Management Capability

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Guerrero, Josep M.; Vasquez, Juan Carlos

    2014-01-01

    of batteries and loads to form an autonomous dc Microgrid (MG). To overcome the control challenge associated with coordination of multiple batteries within one stand-alone MG, a double-layer hierarchical control strategy was proposed; 1) The unit-level primary control layer was established by an adaptive...... tracking (MPPT) for renewable energy sources (RESs), with which a smooth on-line overlap was designed; 2) the supervisory control layer was designed to use the low bandwidth communication interface between the central controller and sources in order to collect data needed for adaptive calculation...

  1. Comparison of two methods of inquiry for torture with East African refugees: single query versus checklist.

    Science.gov (United States)

    Westermeyer, Joseph; Hollifield, Michael; Spring, Marline; Johnson, David; Jaranson, James

    2011-01-01

    First to compare two methods of inquiry regarding torture: i.e., the traditional means of inquiry versus a checklist of torture experiences previously identified for these African refugees. Second, we hoped to identify factors that might influence refugees to not report torture on a single query when checklist data indicated torture events had occurred or to report torture when checklist data indicated that torture had not occurred. Consisted of queries to 1,134 community-dwelling East African refugees (Somalia and Ethiopia) regarding the presence-versus-absence of torture in Africa (single query), a checklist of torture experiences in Africa that we had previously identified as occurring in these groups, demography, non-torture traumatic experiences in Africa, and current posttraumatic symptoms. Showed that 14% of the study participants reported a torture experience on a checklist, but not on a single query. Nine percent responded positively to the single query on torture, but then failed to check any torture experience. Those reporting trauma on an open-ended query, but not on a checklist, had been highly traumatized in other ways (warfare, civil chaos, robbery, assault, rape, trauma during flight out of the country). Those who reported torture on the checklist but not on the single query reported fewer instances of torture, suggesting that perhaps a "threshold" of torture experience influenced the single-query report. In addition, certain types of torture appeared more apt to be associated with a singlequery endorsement of torture. On regression analysis, a single-query self-report of torture was associated with traumatic experiences consistent with torture, older age, female gender, and nontorture trauma in Africa. Inconsistent reporting of torture occurred when two methods of inquiry (one openended and one a checklist) were employed in this sample. We believe that specific contexts of torture and non-torture trauma, together with individual demographic

  2. Command and Control Career Ladder, AFSC 274X0.

    Science.gov (United States)

    1987-04-01

    I COMMAND AND CONTROL CAREER LADDER AFSC 274X0 AFPT 90-274-774 APRIL 1987 OCCUPATIONAL ANALYSIS PROGRAM USAF OCCUPATIONAL MEASUREMENT CENTER AIR...3 HQ TAC/TTGT 1 1 HQ USAF/XODRF 1 1 HQ USAF/ MPPT 1 1 HQ USAFE/DPAT 3 3 HQ USAFE/TTGT 1 1 HO USMC (CODE TPI) 1 NODAC 1 3300 TCHTW/TTGX (KEESLER AFB MS...Command and Control career ladder (AFSC 274X0). This survey was requested by the Training Development Services Division of the USAF Occupa- tional

  3. Indirect sensorless speed control of a PMSG for wind application

    DEFF Research Database (Denmark)

    Diaz, S.A.; Silva, C.; Juliet, J.

    2009-01-01

    in sensorless strategies are avoided. The sensorless scheme proposed here is based on a synchronous d-q frame phaselocked loop (PLL) for back-emf estimation, as those used in voltage phase detection for grid connected converters. The wind turbine control includes maximum power point tracking (MPPT) using......In this paper, the sensorless control of a permanent magnet synchronous generator (PMSG) for wind turbine applications is presented. This kind of generator has many advantages, such as: high efficiency, high power density and low maintenance requirements. To improve these characteristics...

  4. DDE in birds' eggs: Comparisons of two methods for estimating critical levels

    Science.gov (United States)

    Blus, L.J.

    1984-01-01

    The sample egg technique and eggshell thickness-residue regression analysis were comparatively evaluated as tools in estimating critical levels of DDE in birds? eggs that seriously affect reproductive successa nd population starts....In comparing critical values of DDE that were derived from the two methods, the estimates were lower using the sample egg technique for both the Brown Pelican (3 ?g/g vs 8 ?g/g) and the Black-crowned Night-Heron (12?g/g/ vs 54 ?g/g) assuming a critical value of eggshell thinning at 20%....Extension of the regression line beyond the eggshell thickness-DDE residue data base is likely to result in spurious critical values of DDE. When sufficient thickness and residue data are available for estimating critical values of DDE from the regression equation, the estimates are meaningful but are likely to be inflated because adverse effects unrelated to eggshell thinning such as parental behavior and embryotoxicity unrelated to eggshell deficiencies are not taken into account.....Establishing critical levels of pollutants in eggs and tissues is a necessary procedure in assessing effects of these chemicals on individuals and populations of sensitive species. There are inherent difficulties in quantifying the effects of any pollutant on population trends and declines in productivity. The sample egg technique is apparently a more sensitive method for estimating critical levels of DDE, but some subjective interpretation is required for results obtained by both methods.

  5. Evaluation of urinary cortisol excretion by radioimmunoassay through two methods (extracted and non-extracted)

    International Nuclear Information System (INIS)

    Fonte Kohek, M.B. da; Mendonca, B.B. de; Nicolau, W.

    1993-01-01

    The objective of this paper is to compare the feasibility, sensitivity and specificity of both methods (extracted versus non-extracted) in the hypercortisolism diagnosis. It used Gamma Coat 125 cortisol Kit provided by Clinical Assays, Incstar, USA, for both methods extracting it with methylene chloride in order to measure the extracted cortisol. It was performed 32 assays from which it was obtained from 0.1 to 0.47 u g/d l of sensitivity. The intra-run precision was varied from 8.29 +- 3.38% and 8.19 +-4.72% for high and low levels, respectively for non-extracted cortisol, and 9.72 +- 1.94% and 9.54 +- 44% for high and low levels, respectively, for extracted cortisol. The inter-run precision was 15.98% and 16.15% for high level of non-extracted cortisol, respectively. For the low level it obtained 17.25% and 18.59% for non-extracted and extracted cortisol respectively. It was evaluated 24-hour urine basal samples from 43 normal subjects, and 53 obese (body mass index > 30) and 53 Cushing's syndrome patients. The sensitivity of the methods were similar (100% and 98.1% for non-extracted and extracted methods, respectively) and the specificity was the same for both methods (100%). It was noticed a positive correlation between the two methods in all the groups studied (p s syndrome. (author)

  6. Comparison of two methods for RNA extraction from the nucleus pulposus of intervertebral discs.

    Science.gov (United States)

    Gan, M F; Yang, H L; Qian, J L; Wu, C S; Yuan, C X; Li, X F; Zou, J

    2016-06-03

    RNA extraction from the nucleus pulposus of intervertebral discs has been extensively used in orthopedic studies. We compared two methods for extracting RNA from the nucleus pulposus: liquid nitrogen grinding and enzyme digestion. The RNA was detected by agarose gel electrophoresis, and the purity was evaluated by absorbance ratio using a spectrophotometer. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression was assayed by reverse transcription-polymerase chain reaction (RT-PCR). Thirty human lumbar intervertebral discs were used in this study. The liquid nitrogen-grinding method was used for RNA extraction from 15 samples, and the mean RNA concentration was 491.04 ± 44.16 ng/mL. The enzyme digestion method was used on 15 samples, and the mean RNA concentration was 898.42 ± 38.64 ng/mL. The statistical analysis revealed that there was a significant difference in concentration between the different methods. Apparent 28S, 18S, and 5S bands were detectable in RNA extracted using the enzyme digestion method, whereas no 28S or 18S bands were detected in RNA extracted using the liquid nitrogen-grinding method. The GAPDH band was visible, and no non-specific band was detected in the RT-PCR assay by the enzyme digestion method. Therefore, the enzyme digestion method is an efficient and easy method for RNA extraction from the nucleus pulposus of intervertebral discs for further intervertebral disc degeneration-related studies.

  7. Evaluating wind energy potential in Gorgan–Iran using two methods of Weibull distribution function

    Directory of Open Access Journals (Sweden)

    Mehdi Hashemi-Tilehnoee

    2016-02-01

    Full Text Available In this study, wind energy characteristics of the, a city in northeast of Iran, measured at 10m height in 2014. The Gorgan airport one hour recorded data extrapolated to 50m height. The data have been statistically analyzed hourly, daily, monthly, seasonally and annually to determine the wind power potential. Weibull distribution function has been used to determine the wind power density and then the potential energy. Standard deviation method and power density method are the methods used to calculate the scaling and shaping parameters of the Weibull distribution function. The annual mean wind power calculated by the standard deviation method and the power density method is 38.98w/m2 and 41.32w/m2, respectively. By comparing the results concluded that the power density method is a better method than the standard deviation method. In addition, Gorgan wind energy potentiality categorized into class 1. So is unsuitable to utilize large wind energy turbine. Article History: Received November 21, 2015; Received in revised form January 15, 2016; Accepted February 10, 2016; Available online How to Cite This Article: Babayani, D., Khaleghi, M., Tashakor, S., and Hashemi-Tilehnoee.,M. (2016 Evaluating wind energy potential in Gorgan–Iran using two methods of Weibull distribution function. Int. Journal of Renewable Energy Development, 5(1, 43-48. http://dx.doi.org/10.14710/ijred.5.1.43-48 

  8. Evaluation of two methods of deliberative participation of older people in food-policy development.

    Science.gov (United States)

    Timotijevic, Lada; Raats, Monique Maria

    2007-08-01

    This paper reports on an evaluation study of two deliberative methods of public participation of the "hard-to-reach" in food-policy development--the citizens' workshop and the citizens' jury. The participation was conducted on a live food-policy topic (food retailing) and the specific hard-to-reach group of older people was recruited. The evaluation of the two methods was based on an assessment of the participants' and observers' perceptions of the processes and outcomes of the methods, against a set of evaluation criteria, spanning both the individual and group level of analysis. The evaluation used a quasi-experimental, between groups, pre- and post-participation design. The study showed that the properties of the methods alone, such as availability of extra information, had little impact on both satisfaction with the process and the actual task outcomes. It further emphasised the importance of group debate for the perceived satisfaction with the process and the subjective outcomes of the event. The study illustrated that the high level of process satisfaction was not contemporaneous with the perceived impact of participation, such as its perceived influence of policy decision-making, suggesting that the relationship between participation outcomes (i.e. impact of participation) and processes was a complex one. It is argued here that this relationship should be considered in the light of identity processes and the context of public participation.

  9. An assessment of two methods for identifying undocumented levees using remotely sensed data

    Science.gov (United States)

    Czuba, Christiana R.; Williams, Byron K.; Westman, Jack; LeClaire, Keith

    2015-01-01

    Many undocumented and commonly unmaintained levees exist in the landscape complicating flood forecasting, risk management, and emergency response. This report describes a pilot study completed by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers to assess two methods to identify undocumented levees by using remotely sensed, high-resolution topographic data. For the first method, the U.S. Army Corps of Engineers examined hillshades computed from a digital elevation model that was derived from light detection and ranging (lidar) to visually identify potential levees and then used detailed site visits to assess the validity of the identifications. For the second method, the U.S. Geological Survey applied a wavelet transform to a lidar-derived digital elevation model to identify potential levees. The hillshade method was applied to Delano, Minnesota, and the wavelet-transform method was applied to Delano and Springfield, Minnesota. Both methods were successful in identifying levees but also identified other features that required interpretation to differentiate from levees such as constructed barriers, high banks, and bluffs. Both methods are complementary to each other, and a potential conjunctive method for testing in the future includes (1) use of the wavelet-transform method to rapidly identify slope-break features in high-resolution topographic data, (2) further examination of topographic data using hillshades and aerial photographs to classify features and map potential levees, and (3) a verification check of each identified potential levee with local officials and field visits.

  10. Flow Control in Wells Turbines for Harnessing Maximum Wave Power.

    Science.gov (United States)

    Lekube, Jon; Garrido, Aitor J; Garrido, Izaskun; Otaola, Erlantz; Maseda, Javier

    2018-02-10

    Oceans, and particularly waves, offer a huge potential for energy harnessing all over the world. Nevertheless, the performance of current energy converters does not yet allow us to use the wave energy efficiently. However, new control techniques can improve the efficiency of energy converters. In this sense, the plant sensors play a key role within the control scheme, as necessary tools for parameter measuring and monitoring that are then used as control input variables to the feedback loop. Therefore, the aim of this work is to manage the rotational speed control loop in order to optimize the output power. With the help of outward looking sensors, a Maximum Power Point Tracking (MPPT) technique is employed to maximize the system efficiency. Then, the control decisions are based on the pressure drop measured by pressure sensors located along the turbine. A complete wave-to-wire model is developed so as to validate the performance of the proposed control method. For this purpose, a novel sensor-based flow controller is implemented based on the different measured signals. Thus, the performance of the proposed controller has been analyzed and compared with a case of uncontrolled plant. The simulations demonstrate that the flow control-based MPPT strategy is able to increase the output power, and they confirm both the viability and goodness.

  11. Maximum Power Point Tracking Implementation by Dspace Controller Integrated Through Z-Source Inverter Using Particle Swarm Optimization Technique for Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Kalaiarasi N.

    2018-01-01

    Full Text Available Maximum Power Point Tracking (MPPT technique is used to extract maximum power from the photovoltaic system. This paper involves working on an enhanced Particle Swarm Optimization (PSO based MPPT method for the photovoltaic (PV system integrated through Z-Source inverter. The main benefit of the proposed method is the diminishing of the steady-state oscillation when the maximum power point (MPP is located. Additionally, during an extreme environmental condition, such as partial shading and large fluctuations of irradiance and temperature, the proposed method has the capability to track the MPP. This algorithm is implemented in dspace 1104 controller. MATLAB simulations are carried out under varying irradiance and temperature conditions to evaluate its effectiveness. Its performance is compared with a conventional method like Perturb and observe (P&O method.

  12. Comparison of Two Methods Used to Model Shape Parameters of Pareto Distributions

    Science.gov (United States)

    Liu, C.; Charpentier, R.R.; Su, J.

    2011-01-01

    Two methods are compared for estimating the shape parameters of Pareto field-size (or pool-size) distributions for petroleum resource assessment. Both methods assume mature exploration in which most of the larger fields have been discovered. Both methods use the sizes of larger discovered fields to estimate the numbers and sizes of smaller fields: (1) the tail-truncated method uses a plot of field size versus size rank, and (2) the log-geometric method uses data binned in field-size classes and the ratios of adjacent bin counts. Simulation experiments were conducted using discovered oil and gas pool-size distributions from four petroleum systems in Alberta, Canada and using Pareto distributions generated by Monte Carlo simulation. The estimates of the shape parameters of the Pareto distributions, calculated by both the tail-truncated and log-geometric methods, generally stabilize where discovered pool numbers are greater than 100. However, with fewer than 100 discoveries, these estimates can vary greatly with each new discovery. The estimated shape parameters of the tail-truncated method are more stable and larger than those of the log-geometric method where the number of discovered pools is more than 100. Both methods, however, tend to underestimate the shape parameter. Monte Carlo simulation was also used to create sequences of discovered pool sizes by sampling from a Pareto distribution with a discovery process model using a defined exploration efficiency (in order to show how biased the sampling was in favor of larger fields being discovered first). A higher (more biased) exploration efficiency gives better estimates of the Pareto shape parameters. ?? 2011 International Association for Mathematical Geosciences.

  13. Comparison of two methods of therapy level calibration at 60Co gamma beams

    International Nuclear Information System (INIS)

    Bjerke, H.; Jaervinen, H.; Grimbergen, T.W.M.; Grindborg, J.E.; Chauvenet, B.; Czap, L.; Ennow, K.; Moretti, C.; Rocha, P.

    1998-01-01

    The accuracy and traceability of the calibration of radiotherapy dosimeters is of great concern to those involved in the delivery of radiotherapy. It has been proposed that calibration should be carried out directly in terms of absorbed dose to water, instead of using the conventional and widely applied quantity of air kerma. In this study, the faithfulness in disseminating standards of both air kerma and absorbed dose to water were evaluated, through comparison of both types of calibration for three types of commonly used radiotherapy dosimeters at 60 Co gamma beams at a few secondary and primary standard dosimetry laboratories (SSDLs and PSDLs). A supplementary aim was to demonstrate the impact which the change in the method of calibration would have on clinical dose measurements at the reference point. Within the estimated uncertainties, both the air kerma and absorbed dose to water calibration factors obtained at different laboratories were regarded as consistent. As might be expected, between the SSDLs traceable to the same PSDL the observed differences were smaller (less than 0.5%) than between PSDLs or SSDLs traceable to different PSDLs (up to 1.5%). This can mainly be attributed to the reported differences between the primary standards. The calibration factors obtained by the two methods differed by up to about 1.5% depending on the primary standards involved and on the parameters of calculation used for 60 Co gamma radiation. It is concluded that this discrepancy should be settled before the new method of calibration at 60 Co gamma beams in terms of absorbed dose to water is taken into routine use. (author)

  14. Comparison of two methods of therapy level calibration at 60Co gamma beams

    International Nuclear Information System (INIS)

    Bjerke, H; Jaervinen, H; Grimbergen, T W M; Grindborg, J-E; Chauvenet, B; Czap, L; Ennow, K; Moretti, C; Rocha, P

    1998-01-01

    The accuracy and traceability of the calibration of radiotherapy dosimeters is of great concern to those involved in the delivery of radiotherapy. It has been proposed that calibration should be carried out directly in terms of absorbed dose to water, instead of using the conventional and widely applied quantity of air kerma. In this study, the faithfulness in disseminating standards of both air kerma and absorbed dose to water were evaluated, through comparison of both types of calibration for three types of commonly used radiotherapy dosimeters at 60 Co gamma beams at a few secondary and primary standard dosimetry laboratories (SSDLs and PSDLs). A supplementary aim was to demonstrate the impact which the change in the method of calibration would have on clinical dose measurements at the reference point. Within the estimated uncertainties, both the air kerma and absorbed dose to water calibration factors obtained at different laboratories were regarded as consistent. As might be expected, between the SSDLs traceable to the same PSDL the observed differences were smaller (less than 0.5%) than between PSDLs or SSDLs traceable to different PSDLs (up to 1.5%). This can mainly be attributed to the reported differences between the primary standards. The calibration factors obtained by the two methods differed by up to about 1.5% depending on the primary standards involved and on the parameters of calculation used for 60 Co gamma radiation. It is concluded that this discrepancy should be settled before the new method of calibration at 60 Co gamma beams in terms of absorbed dose to water is taken into routine use

  15. On-Line Target Position Localization in the Presence of Respiration: A Comparison of two Methods

    International Nuclear Information System (INIS)

    Hugo, Geoffrey D.; Liang Jian; Campbell, Jonathan; Yan Di

    2007-01-01

    Purpose: To compare two 'four-dimensional' methods for image-guided target localization in the presence of respiration. Methods and Materials: Four-dimensional image guidance was performed with two methods. A respiration-correlated computed tomography (RCCT) was acquired on a CT simulator, and an average CT (AVG-CT) image was generated from the RCCT. A respiration-correlated cone-beam CT (RC-CBCT) and a free-breathing cone-beam CT (FB-CBCT) were acquired. The 'RCCT method' consisted of calculating the mean target position on both the RCCT and RC-CBCT, registering the RCCT to the RC-CBCT, and determining the shift in the mean target position from the planned mean position. The 'AVG-CT method' consisted of registering the AVG-CT to the FB-CBCT. The ability of each to measure the shift in the mean target position was compared, both in a respiratory phantom and in 8 patients. Results: In phantom, the RCCT and AVG-CT methods were able to measure the true mean target position to within 0.15 cm and 0.10 cm, respectively. In the patient study, the mean error between the methods was 0.13 cm (left-right), 0.14 cm (anterior-posterior), and 0.10 cm (cranio-caudal). The error was not observed to vary with tumor position or magnitude of tumor motion. Conclusions: Respiration may impact the on-line image guidance process. The RCCT method enables localization of the mean tumor position and measurement of changes in the motion pattern, whereas the AVG-CT method is simple, fast, and easily implemented. We found the methods to be nearly equivalent in detecting shifts in the mean tumor position

  16. Two methods for decreasing the flexibility gap in national energy systems

    International Nuclear Information System (INIS)

    Batas Bjelić, Ilija; Rajaković, Nikola; Krajačić, Goran; Duić, Neven

    2016-01-01

    More variable renewable energy sources and energy efficiency measures create an additional flexibility gap and require a novel energy planning method for sustainable national energy systems. The firstly presented method uses only EnergyPLAN tool in order to decrease the flexibility gap in a national energy system. Generic Optimization program (GenOpt ® ) is an optimization program for the minimization of a cost function that is evaluated by an external simulation program, such as EnergyPLAN, which was used as the second method in this research. Successful strategies to decrease the flexibility gap are verified on the case of the Serbian national energy system using two methods for its structure design: (1) the iterative method, based on heuristics and manual procedure of using only EnergyPLAN, and (2) the optimization method, based on soft-linking of EnergyPLAN with GenOpt ® . The latter method, named EPOPT (EnergyPlan-genOPT), found the solution for the structure of the sustainable national energy system at the total cost of 8190 M€, while the iterative method was only able to find solutions at the cost in the range of 8251–8598 M€ by targeting only one sustainability goal. The advantages of the EPOPT method are its accuracy, user-friendliness and minimal costs, are valuable for planners. - Highlights: • Heuristic and optimization method for sustainable national energy system structure. • The same input assumptions resulting in different energy system structure. • Both methods are successful in decreasing of the flexibility gap. • The EPOPT method advantages are in the speed, accuracy and planner comfort. • Advanced method for the sustainable national energy policy planning.

  17. [Comparison of Two Methods of Lidocaine Administrating for Neuroprotection in Rabbit Model of Subarachnoid Hemorrhage].

    Science.gov (United States)

    Shi, Xian-Qing; Fu, Yong-Jian; Zheng, Li-Rong

    2017-01-01

    To compare the neuroprotection effect of two methods of Lidocaine administration in rabbit model of subarachnoid hemorrhage. Forty New Zealand white rabbits were randomly divided into sham group, subarachnoid hemorrhage group (SAH), Lidocaine intravenous injection group (L1), and Lidocaine intracisternal administration group (L2). The rabbits were given general anaesthesia, then 1.5 mL autologous nonheparinized arterial blood was injected into cisterna magna to establish SAH model, while 1.5 mL saline was used in sham group. Thirty minutes later, the rabbits in L1 and L2 group respectively received 0.3 mL 2% Lidocaine administration of intravenously and intracisternally injection. All animals were sacrificed at 72 h after SAH. The samples of basilar artery and hippocampus tissue were processed for morphometric analysis. At pre-operation and 72 h after SAH, the level of interleukin-6 (IL-6) in serum was measured. HE staining and C fos immunohistochemical staining were performed in L1 and L2 groups. Artery area and artery diameter of basal arteries, normal neuron density and C-fos positive cell in hippocampus were measured at 72 h after SAH. The baseline level of IL-6 was not significant different in four groups ( P >0.05). The level of IL-6 at 72 h after SAH was significantly higher than that at pre-operation in SAH, L1 and L2 groups ( P L1 group was higher than that in L2 group ( P L2 group, the cross-section area and diameter of basal artery were smaller in SAH and L1 group, while the normal neuron density of hippocampus was less ( P <0.05). Intracisternal administration of Lidocaine could provide neuroprotection in rabbit model of subarachnoid hemorrhage.

  18. Comparison of two methods for alveolar bone loss measurement in an experimental periodontal disease model in rats

    Directory of Open Access Journals (Sweden)

    Diego Nique Liberman

    2011-02-01

    Full Text Available There are many studies that evaluate possible risk factors for periodontal diseases in animals. Most of them have focused only on the biological aspects of disease occurrence; therefore, it has been difficult to compare studies of the different methodological approaches. The aim of the present study was to compare different methods - linear and area - of the evaluation of morphometrical alveolar bone loss. Sixty hemimaxillae, defleshed and stained with 1% methylene blue to delineate the cementoenamel junction and alveolar bone crest, were obtained from a previous study that induced periodontal disease by means of ligatures in two groups of fifteen Wistar rats during 9 weeks. Ligatures were placed around the right upper second molars, and the contra-lateral teeth remained as intra-group controls. Digital photographs were taken from the specimens and submitted to a single, calibrated, blind examiner who performed the morphometrical evaluation of alveolar bone loss using both linear and area methods. Mean values of linear and area measurements were obtained from each side - buccal and palatal - of the specimens. The degree of association between the two methods was determined by Pearson's Correlation Coefficient. An almost perfect association (0.98 was determined between the linear and area evaluations. A mathematical formula was subsequently created to estimate the total area of alveolar bone loss, from linear mean measurements. Both methods were suitable for detecting bone level alterations. The results of the present study allow for the transformation of data and better compilation of results from different studies.

  19. Switching Control of Wind Turbine Sub-Controllers Based on an Active Disturbance Rejection Technique

    Directory of Open Access Journals (Sweden)

    Yancai Xiao

    2016-10-01

    Full Text Available Wind power generation systems require complex control systems with multiple working conditions and multiple controllers. Under different operating conditions, switching without disturbancebetweenthesub-controllersplaysacriticalroleinensuringthestabilityofpowersystems. The sub-controllers of two typical cases in the permanent magnet direct drive (PMDD wind turbine running process are studied, one is the proportional integral (PI controller in the maximum power points tracking (MPPT stage, the other is the fuzzy pitch angle controller in the constant power stage. The switching strategy of the two sub-controllers is the emphasis in this research. Based on the active disturbance rejection control (ADRC, the switching mode of the sub-controllers is proposed, which can effectively restrain the sudden changes of the rotor current during the switching process, and improve the quality of power generation. The feasibility and effectiveness of the sub-controller switching strategy is verified by Matlab/Simulink simulation for a 2 MW PMDD wind turbine.

  20. Comparative analysis of two methods for measuring sales volumes during malaria medicine outlet surveys.

    Science.gov (United States)

    Patouillard, Edith; Kleinschmidt, Immo; Hanson, Kara; Pok, Sochea; Palafox, Benjamin; Tougher, Sarah; O'Connell, Kate; Goodman, Catherine

    2013-09-05

    There is increased interest in using commercial providers for improving access to quality malaria treatment. Understanding their current role is an essential first step, notably in terms of the volume of diagnostics and anti-malarials they sell. Sales volume data can be used to measure the importance of different provider and product types, frequency of parasitological diagnosis and impact of interventions. Several methods for measuring sales volumes are available, yet all have methodological challenges and evidence is lacking on the comparability of different methods. Using sales volume data on anti-malarials and rapid diagnostic tests (RDTs) for malaria collected through provider recall (RC) and retail audits (RA), this study measures the degree of agreement between the two methods at wholesale and retail commercial providers in Cambodia following the Bland-Altman approach. Relative strengths and weaknesses of the methods were also investigated through qualitative research with fieldworkers. A total of 67 wholesalers and 107 retailers were sampled. Wholesale sales volumes were estimated through both methods for 62 anti-malarials and 23 RDTs and retail volumes for 113 anti-malarials and 33 RDTs. At wholesale outlets, RA estimates for anti-malarial sales were on average higher than RC estimates (mean difference of four adult equivalent treatment doses (95% CI 0.6-7.2)), equivalent to 30% of mean sales volumes. For RDTs at wholesalers, the between-method mean difference was not statistically significant (one test, 95% CI -6.0-4.0). At retail outlets, between-method differences for both anti-malarials and RDTs increased with larger volumes being measured, so mean differences were not a meaningful measure of agreement between the methods. Qualitative research revealed that in Cambodia where sales volumes are small, RC had key advantages: providers were perceived to remember more easily their sales volumes and find RC less invasive; fieldworkers found it more

  1. Comparative evaluation of two methods care of the perioperative period after laparoscopic operations on uterine appendages

    Directory of Open Access Journals (Sweden)

    О. S. Lashkul

    2017-10-01

    Full Text Available Aim – тo assess the impact of the early multimodal rehabilitation concept on postoperative period after laparoscopic operations on uterine appendages. Маterials and methods. The study involved 79 patients who were randomized by envelope method in two groups. In the main group (26 patients, a protocol of early multimodal rehabilitation (ERAS was used. In the control group (53 patients, the traditional perioperative regimen was used. In both groups, laparoscopic operations were performed under general anesthesia with mechanical ventilation (propofol + fentanyl. In perioperative anesthesia NSAIDs (dexketoprofen, ketorolac, paracetamol were included. Non-invasive monitoring was performed by the «Leon» monitor (StO2, blood pressure, heart rate, capnogram, hourly diuresis was taken into account, thermometry was performed. In the postoperative period analgesia with combination with systemic administration of dexketoprofen (100–150 mg/day + ketorolac (60 mg/day + paracetamol (3000 mg/day was used. Results. The groups were homogeneous according to anamnestic (the beginning of menstruation, the number of pregnancies, childbirth, abortions, miscarriages, anthropometric and demographic characteristics, the duration of operations, blood loss and baseline values of systolic, diastolic, mean arterial pressures and heart rate. In groups the volumes of diuresis did not differ significantly (p < 0.05. Positive intraoperative hemohydrate balance in the FTS group was almost half that in the control group. When assessing pain at rest by VAS, a statistically significant difference was found at the 6 and 24 hours study stages. Nevertheless, at the study stages the pain level in the control group did not exceed 30 mm, which indicates adequate analgesia at rest. The level of cough pain in the control group exceeded the level of pain in the main group, the statistical difference was determined after 6 hours and 24 hours, but was above 30 mm, which required

  2. Boost converter with combined control loop for a stand-alone photovoltaic battery charge system

    DEFF Research Database (Denmark)

    Mira Albert, Maria del Carmen; Knott, Arnold; Thomsen, Ole Cornelius

    2013-01-01

    frequency avoids perturbations in the load being propagated to the photovoltaic panel and thus deviating the operating point. Linearization of the photovoltaic panel and converter state-space modeling is performed. In order to achieve stable operation under all operating conditions, the photovoltaic panel......The converter control scheme plays an important role in the performance of maximum power point tracking (MPPT) algorithms. In this paper, an input voltage control with double loop for a stand-alone photovoltaic system is designed and tested. The inner current control loop with high crossover...

  3. Comparison of Two Methods of Direct and Indirect Education on Osteoporosis Preventive Behaviors among Female Students

    Directory of Open Access Journals (Sweden)

    Leila Darabi

    2017-08-01

    Full Text Available Background Osteoporosis is the most common metabolic bone disease that decreases bone mass, causes destruction and eventually friability. This disease is preventable, and because adolescent females are the high-risk population, teaching this age group is of the utmost importance. The aim of this study was to compare the effects of the two educational methods (Lecture and Pamphlet on osteoporosis preventive behaviors among female students. Materials and Methods: This was a randomized clinical trial (RCT. To collect data, demographic questionnaire, food frequency questionnaire (FFQ, and physical activity questionnaire were used. Subjects were 205 seventh-grade girls who were selected by multistage random method and allocated in two experimental (Lecture = 68, Pamphlet = 67 and 70 for control group. In the Lecture group, there were 5 sessions of training, each of which lasted 60 minutes. In the Pamphlet group, only educational pamphlets were given, and no interventions were performed in the control group. Data were analyzed through statistical software SPSS version 21.0. Descriptive statistics, chi-square tests, t-test and ANOVA were applied to analyze the data. Results: The mean age of the students was 13 + 0.856 years old and there was no difference in terms of demographic variables between intervention and control groups. The results identified the mean scores of physical activity behaviors significantly improved two mounts after the intervention in the lecture group (P=0.001.While, the men scores of the pamphlet group had no significant changes after two months, but the differences of the both group compared to the control group were significant. Considering the significant decreased in the control group (P= 001. The mean scores of calcium intake in the two lecture and pamphlet groups significantly increased (P

  4. PSO Based PI Controller Design for a Solar Charger System

    Science.gov (United States)

    Yau, Her-Terng; Lin, Chih-Jer; Liang, Qin-Cheng

    2013-01-01

    Due to global energy crisis and severe environmental pollution, the photovoltaic (PV) system has become one of the most important renewable energy sources. Many previous studies on solar charger integrated system only focus on load charge control or switching Maximum Power Point Tracking (MPPT) and charge control modes. This study used two-stage system, which allows the overall portable solar energy charging system to implement MPPT and optimal charge control of Li-ion battery simultaneously. First, this study designs a DC/DC boost converter of solar power generation, which uses variable step size incremental conductance method (VSINC) to enable the solar cell to track the maximum power point at any time. The voltage was exported from the DC/DC boost converter to the DC/DC buck converter, so that the voltage dropped to proper voltage for charging the battery. The charging system uses constant current/constant voltage (CC/CV) method to charge the lithium battery. In order to obtain the optimum PI charge controller parameters, this study used intelligent algorithm to determine the optimum parameters. According to the simulation and experimental results, the control parameters resulted from PSO have better performance than genetic algorithms (GAs). PMID:23766713

  5. PSO Based PI Controller Design for a Solar Charger System

    Directory of Open Access Journals (Sweden)

    Her-Terng Yau

    2013-01-01

    Full Text Available Due to global energy crisis and severe environmental pollution, the photovoltaic (PV system has become one of the most important renewable energy sources. Many previous studies on solar charger integrated system only focus on load charge control or switching Maximum Power Point Tracking (MPPT and charge control modes. This study used two-stage system, which allows the overall portable solar energy charging system to implement MPPT and optimal charge control of Li-ion battery simultaneously. First, this study designs a DC/DC boost converter of solar power generation, which uses variable step size incremental conductance method (VSINC to enable the solar cell to track the maximum power point at any time. The voltage was exported from the DC/DC boost converter to the DC/DC buck converter, so that the voltage dropped to proper voltage for charging the battery. The charging system uses constant current/constant voltage (CC/CV method to charge the lithium battery. In order to obtain the optimum PI charge controller parameters, this study used intelligent algorithm to determine the optimum parameters. According to the simulation and experimental results, the control parameters resulted from PSO have better performance than genetic algorithms (GAs.

  6. PSO based PI controller design for a solar charger system.

    Science.gov (United States)

    Yau, Her-Terng; Lin, Chih-Jer; Liang, Qin-Cheng

    2013-01-01

    Due to global energy crisis and severe environmental pollution, the photovoltaic (PV) system has become one of the most important renewable energy sources. Many previous studies on solar charger integrated system only focus on load charge control or switching Maximum Power Point Tracking (MPPT) and charge control modes. This study used two-stage system, which allows the overall portable solar energy charging system to implement MPPT and optimal charge control of Li-ion battery simultaneously. First, this study designs a DC/DC boost converter of solar power generation, which uses variable step size incremental conductance method (VSINC) to enable the solar cell to track the maximum power point at any time. The voltage was exported from the DC/DC boost converter to the DC/DC buck converter, so that the voltage dropped to proper voltage for charging the battery. The charging system uses constant current/constant voltage (CC/CV) method to charge the lithium battery. In order to obtain the optimum PI charge controller parameters, this study used intelligent algorithm to determine the optimum parameters. According to the simulation and experimental results, the control parameters resulted from PSO have better performance than genetic algorithms (GAs).

  7. Comparison between two methods to evaluate temperature changes produced by composite light curing units and polymerization techniques.

    Science.gov (United States)

    Loureiro, F H F; Consani, S; Guiraldo, R D; Consani, R L X; Berger, S B; Carvalho, R V; Correr-Sobrinho, L; Sinhoreti, M A C

    2011-10-01

    This study evaluated the temperature change into the pulp chamber during the light curing of composite resin by direct (bovine tooth) and indirect (matrix) methods. Direct method: fifty standardized cavities (2x2x2 mm) were prepared in bovine incisors, which were randomly assigned to evaluation of the temperature changes in the pulp chamber. Indirect method: temperature changes were evaluated through a dentine slice of 1.0 mm thickness in a elastomer cubic mold (2x2x2 mm). Filtek Z250 composite resin (3M/ESPE) was photo-activated using three light curing units: quartz-tungsten-halogen (QTH) by continuous, soft-start or intermittent light modulations; light emitting diode (LED); and plasma arc-curing (PAC). Ten groups (N.=10) were established according to technique evaluation and photo-activation methods. All experiments were carried out in a controlled environment (37 °C and 50 ± 10% relative humidity). The temperature changes were recorded using a digital thermometer attached to a type-K thermocouple in contact with the dentin slice (indirect method) or in contact with the axial wall (dentin) of pulp chamber (direct method). The results were submitted to ANOVA and Tukey's test (α=0.05). Temperature changes were statistically higher for the matrix indirect method (2.56 ºC) than bovine teeth direct method (1.17ºC). The change temperature was statistically higher for the PAC (1.77 ºC) when compared to other photo-activation modes in bovine teeth direct method. The two methods of temperature evaluation were different, however indirect method detected the higher temperature increase. Higher energy density arising from the light curing units and polymerization techniques promoted higher temperature increase.

  8. The effects of two methods of Class III malocclusion treatment on temporomandibular disorders.

    Science.gov (United States)

    Kurt, Hanefi; Alioğlu, Ceylan; Karayazgan, Banu; Tuncer, Necat; Kılıçoğlu, Hülya

    2011-12-01

    The aim of this research was to evaluate, within a controlled clinical study, the effects of a Delaire-type facemask or a modified Jasper Jumper (JJ) used in the treatment of children with Class III malocclusions due to maxillary retrognathia on temporomandibular disorders (TMDs). Forty-six patients with Class III malocclusions referred for orthodontic treatment were divided into two groups, a test and a control. The test group comprised 33 randomly chosen patients (15 females, 18 males) aged 8-11 years. The control group included 13 patients (eight females, five males) with similar features. TMD assessment was performed before and after treatment using a two-axis questionnaire, the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMDs). Qualitative data were evaluated using chi-square and McNemar tests. No statistically significant differences related to the presence of TMD were observed pre- or post-treatment (P > 0.05). The most commonly encountered diagnosis was arthralgia in the JJ group both before and after treatment. Evaluation of joint and muscle regions showed decreased symptoms, apart from the diagnosed discomforts, in the JJ group (P Class III malocclusion treatment did not result in TMD.

  9. Modeling, Simulation and Control of Matrix Convert for Variable Speed Wind Turbine System

    Directory of Open Access Journals (Sweden)

    M. Alizadeh Moghadam

    2015-09-01

    Full Text Available This paper presents modeling, simulation and control of matrix converter (MC for variable speed wind turbine (VSWT system including permanent magnet synchronous generator (PMSG. At a given wind velocity, the power available from a wind turbine is a function of its shaft speed. In order to track maximum power, the MC adjusts the PMSG shaft speed.The proposed control system allowing independent control maximum power point tracking (MPPT of generator side and regulate reactive power of grid side for the operation of the VSWT system. The MPPT is implemented by a new control system. This control system is based on control of zero d-axis current (ZDC. The ZDC control can be realized by transfer the three-phase stator current in the stationary reference frame into d-and q-axis components in the synchronous reference frame. Also this paper is presented, a novel control strategy to regulate the reactive power supplied by a variable speed wind energy conversion system. This control strategy is based on voltage oriented control (VOC. The simulation results based on Simulink/Matlab software show that the controllers can extract maximum power and regulate reactive power under varying wind velocities.

  10. Estimating Apparent Nutrient Digestibility of Diets Containing or Leaf Meals for Growing Rabbits by Two Methods

    Directory of Open Access Journals (Sweden)

    A. M. Safwat

    2015-08-01

    Full Text Available This study aimed to evaluate the nutrient digestibility of growing rabbits fed diets with different levels of either Leucaena leucocephala (LLM or Moringa oleifera (MOLM leaf meals and also to compare total collection and TiO2 marker methods for estimating digestibility. A total of 30 California growing rabbits (1.81±0.19 kg live weight on average were randomly distributed into five experimental groups of six rabbits each and were housed in individual cages. The groups were control, 30% LLM, 40% LLM, 30% MOLM, and 40% MOLM. All groups received pelleted diets for two weeks; diets also contained 4 g/kg titanium dioxide as dietary marker. Daily feed intake was recorded during the whole experimental period and total feces were collected daily and weighed individually during four days. The results showed that there were no difference (p>0.05 in feed, dry matter (DM, organic matter (OM, crude protein (CP, digestible energy, and crude fiber (CF intake between the control group and the other experimental groups. The apparent digestibility values of DM, OM, CP, CF, acid detergent fiber, and gross energy were the highest for control group (p = 0.001, meanwhile MOLM diets had generally higher nutrient digestibility coefficients than LLM diets. Increasing the inclusion level of leaf meal in the diet from 30% to 40% improved the digestibility of CF from 45.02% to 51.69% for LLM and from 48.11% to 55.89% for MOLM. Similar results for apparent nutrient digestibility coefficients were obtained when either total collection or indigestible marker method was used. In conclusion, the digestibility of MOLM containing diets were better than LLM diets, furthermore TiO2 as an external marker could be used as a simple, practical and reliable method to estimate nutrients digestibility in rabbit diets.

  11. Two methods of cervix ripening: intracervical Foley catether and dinoprostone - which one is actually more efficient?

    Science.gov (United States)

    Kosinska-Kaczynska, Katarzyna; Ciechanowicz, Piotr; Saletra, Aleksandra; Szymusik, Iwona; Wielgos, Miroslaw

    2015-01-01

    The aim was to evaluate which of the two analyzed methods of preinduction: intracervical Foley catether and intracervical dinoprostone is related to higher rate of successful vaginal delivery in shorter time and to shorter hospitalization after the delivery. A retrospective analysis of 198 patients with unfavorable cervix for labor induction (Bishop score ≤ 6), hospitalized at 1st Department of Obstetrics and Gynecology, Medical University of Warsaw, was carried out. In 105 patients labor preinduction was conducted with Foley catheter (study group) and in 93 with intracervical dinoprostone (control group). There were no significant differences regarding patients' age, body mass index (BMI), weight gain during the pregnancy, duration of pregnancy and parity between the groups. 68.6% of patients in the study group and 65.6% in the control group delivered vaginally (p=0.65). In the study group significantly less women developed spontaneous onset of labor (36.2% vs 66.7%; p<0.001). The time from preinduction to delivery onset and from preinduction to vaginal delivery were longer in the study group (780 min vs 489 min; 1682 min vs 920 min; p<0.001). The time of hospitalization after the delivery was significantly shorter in the study group (4.1 days vs 6.8; (p<0.001). Both Foley catheter and dinoprostone seem to be equally effective in achieving vaginal delivery. In terms of time effectiveness Foley catheter preinduction is related to longer time from preinduction to delivery, nevertheless shorter time of hospitalization.

  12. Two methods for damping torsional vibrations in DFIG-based wind generators using power converters

    Science.gov (United States)

    Zhao, Zuyi; Lu, Yupu; Xie, Da; Yu, Songtao; Wu, Wangping

    2017-01-01

    This paper proposes novel damping control algorithms by using static synchronous compensator (STATCOM) and energy storage system (ESS) to damp torsional vibrations in doubly fed induction generator (DFIG) based wind turbine systems. It first analyses the operating characteristics of STATCOM and ESS for regulating power variations to increase grid voltage stability. Then, new control strategies for STATCOM and ESS are introduced to damp the vibrations. It is followed by illustration of their effectiveness to damp the drive train torsional vibrations of wind turbines, which can be caused by grid disturbances, such as voltage sags and frequency fluctuations. Results suggest that STATCOM is a promising technology to mitigate the torsional vibrations caused by grid voltage sags. By contrast, the ESS connected to the point of common coupling (PCC) of wind turbine systems shows even obvious advantages because of its capability of absorbing/releasing both active and reactive power. It can thus be concluded that STATCOM is useful for stabilizing power system voltage fluctuations, and ESS is more effective both in regulating PCC voltage fluctuations and damping torsional vibrations caused by grid voltage frequency fluctuations.

  13. Control of Single-Stage Single-Phase PV inverter

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede

    2005-01-01

    In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented......-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (PR) controllers. The control strategy was tested experimentally on 1.5 kW PV inverter........ The main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm using the incremental conductance method; - a synchronization method using the phase-locked-loop (PLL), based on delay; - the input power control using the dc voltage controller and power feed...

  14. A comparison of two methods for assessing awareness of antitobacco television advertisements.

    Science.gov (United States)

    Luxenberg, Michael G; Greenseid, Lija O; Depue, Jacob; Mowery, Andrea; Dreher, Marietta; Larsen, Lindsay S; Schillo, Barbara

    2016-05-01

    This study uses an online survey panel to compare two approaches for assessing ad awareness. The first uses a screenshot of a television ad and the second shows participants a full-length video of the ad. We randomly assigned 1034 Minnesota respondents to view a screenshot or a streaming video from two antitobacco ads. The study used one ad from ClearWay Minnesota's ITALIC! We All Pay the Price campaign, and one from the Centers for Disease Control ITALIC! Tips campaign. The key measure used to assess ad awareness was aided ad recall. Multivariate analyses of recall with cessation behaviour and attitudinal beliefs assessed the validity of these approaches. The respondents who saw the video reported significantly higher recall than those who saw the screenshot. Associations of recall with cessation behaviour and attitudinal beliefs were stronger and in the anticipated direction using the screenshot method. Over 20% of the respondents assigned to the video group could not see the ad. People who were under 45 years old, had incomes greater than $35,000 and women were reportedly less able to access the video. The methodology used to assess recall matters. Campaigns may exaggerate the successes or failures of their media campaigns, depending on the approach they employ and how they compare it to other media campaign evaluations. When incorporating streaming video, researchers should consider accessibility and report possible response bias. Researchers should fully define the measures they use, specify any viewing accessibility issues, and make ad comparisons only when using comparable methods. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  15. A Single-Phase Voltage-Controlled Grid-Connected Photovoltaic System With Power Quality Conditioner Functionality

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Liserre, Marco; Mastromauro, R. A.

    2009-01-01

    Future ancillary services provided by photovoltaic (PV) systems could facilitate their penetration in power systems. Also low power PV systems can be designed to improve the power quality. This paper presents a single-phase photovoltaic system that provides grid voltage support and compensation...... of harmonic distortion at the point of common coupling (PCC) thanks to a repetitive controller. The power provided by the PV panels is controlled by a Maximum Power Point Tracking (MPPT) algorithm based on the incremental conductance method specifically modified to control the phase of the PV inverter voltage...

  16. What Do Children Know about the Interior of the Body? A Comparison of Two Methods of Investigation.

    Science.gov (United States)

    Deluca, Paolo

    This research compared two methods used to investigate the knowledge of internal body parts by children ages 4 to 9 years. Subjects were 50 Italian children: 18 preschoolers, 21 first graders, and 11 second or third graders. Children performed two tasks, a Drawing Task in which they drew on the outline of a human figure all the body parts they…

  17. Effects of high dose methylprednisolone pulse therapy on bone mass and biochemical markers of bone metabolism in patients with active rheumatoid arthritis: a 12-month randomized prospective controlled study.

    Science.gov (United States)

    Frediani, Bruno; Falsetti, Paolo; Bisogno, Stefania; Baldi, Fabio; Acciai, Caterina; Filippou, Georgios; Bacarelli, Maria Romana; Filipponi, Paolo; Galeazzi, Mauro; Marcolongo, Roberto

    2004-06-01

    To study the effects of one year of high dose 6-methylprednisolone pulse therapy (MPPT) on bone mass, seric bone alkaline phosphatase (sBAP), and urinary deoxypyridinoline (uDpyr) in patients with active rheumatoid arthritis (RA), and to compare results with those of patients with active RA treated with oral methylprednisolone (OMP). Thirty-one women with active RA were given 1000 mg of MP IV for 3 alternate days, with a mean interval of administration of 76 days (+/- 8.3 SD) for one year (MPPT group). Bone mineral density (BMD) (total body, lumbar spine, and femur neck), plasma levels of sBAP, and urinary concentrations of uDpyr were assessed at the beginning of the treatment and every 3 months until the end of the study. Moreover, erythrocyte sedimentation rate (ESR), Thompson joint score, and early morning stiffness were assessed at study entry and every month. The control group, 31 women with active RA treated with oral MP, was followed in the same way (OMP group). In the MPPT group there was no significant reduction of BMD at any site compared to significant reductions in lumbar BMD at 6 and 12 months and total body BMD and femur neck BMD at 12 months in the OMP group. Also in the OMP group, a significant reduction in the mean sBAP was observed. The mean uDpyr levels were not significantly reduced in either group. Our results show that MPPT, compared to continuous therapy with oral corticosteroids, preserves bone mass without modifying the biochemical markers of bone metabolism.

  18. Power Control and Optimization of Photovoltaic and Wind Energy Conversion Systems

    Science.gov (United States)

    Ghaffari, Azad

    Power map and Maximum Power Point (MPP) of Photovoltaic (PV) and Wind Energy Conversion Systems (WECS) highly depend on system dynamics and environmental parameters, e.g., solar irradiance, temperature, and wind speed. Power optimization algorithms for PV systems and WECS are collectively known as Maximum Power Point Tracking (MPPT) algorithm. Gradient-based Extremum Seeking (ES), as a non-model-based MPPT algorithm, governs the system to its peak point on the steepest descent curve regardless of changes of the system dynamics and variations of the environmental parameters. Since the power map shape defines the gradient vector, then a close estimate of the power map shape is needed to create user assignable transients in the MPPT algorithm. The Hessian gives a precise estimate of the power map in a neighborhood around the MPP. The estimate of the inverse of the Hessian in combination with the estimate of the gradient vector are the key parts to implement the Newton-based ES algorithm. Hence, we generate an estimate of the Hessian using our proposed perturbation matrix. Also, we introduce a dynamic estimator to calculate the inverse of the Hessian which is an essential part of our algorithm. We present various simulations and experiments on the micro-converter PV systems to verify the validity of our proposed algorithm. The ES scheme can also be used in combination with other control algorithms to achieve desired closed-loop performance. The WECS dynamics is slow which causes even slower response time for the MPPT based on the ES. Hence, we present a control scheme, extended from Field-Oriented Control (FOC), in combination with feedback linearization to reduce the convergence time of the closed-loop system. Furthermore, the nonlinear control prevents magnetic saturation of the stator of the Induction Generator (IG). The proposed control algorithm in combination with the ES guarantees the closed-loop system robustness with respect to high level parameter uncertainty

  19. Comparison of Extremum-Seeking Control Techniques for Maximum Power Point Tracking in Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    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.

  20. Realization and control of a wind turbine connected to the grid by using PMSG

    International Nuclear Information System (INIS)

    Dahbi, Abdeldjalil; Hachemi, Mabrouk; Nait-Said, Nasreddine; Nait-Said, Mohamed-Said

    2014-01-01

    Highlights: • Realization and control of a wind turbine. • Control of the system. • Injection to grid. - Abstract: This paper studies the control of a variable-speed wind turbine using the permanent magnet synchronous generator (PMSG) driven by a wind turbine emulator. The wind turbine is realized by imposing the wind profile on emulator to behave as the real wind turbine when it receives the same wind profile. This wind turbine is connected to the grid by means of a two back-to-back voltage-fed pulse width-modulation (PWM) converters to interface the generator and the grid. This paper has three main objectives, the first is realization of the wind turbine emulator, the second is extracting and exploiting the maximum power from the wind, the third is feeding the grid by high-power and good electrical energy quality; to achieve that, we applied the strategies of maximum power point tracking (MPPT) using optimal torque control which allows the PMSG to operate at an optimal speed. The inverter is used for delivering power to the grid, controlled in a way to deliver only the active power into the grid, thus we have unit power factor. DC-link voltage is also controlled by the inverter. This paper shows the dynamic performances of the complete system by its simulation using Matlab Simulink. Experimental results has verified and validated the wind turbine emulator and the efficiency of MPPT control method using a variable wind profile

  1. Model Predictive Control techniques with application to photovoltaic, DC Microgrid, and a multi-sourced hybrid energy system

    Science.gov (United States)

    Shadmand, Mohammad Bagher

    Renewable energy sources continue to gain popularity. However, two major limitations exist that prevent widespread adoption: availability and variability of the electricity generated and the cost of the equipment. The focus of this dissertation is Model Predictive Control (MPC) for optimal sized photovoltaic (PV), DC Microgrid, and multi-sourced hybrid energy systems. The main considered applications are: maximum power point tracking (MPPT) by MPC, droop predictive control of DC microgrid, MPC of grid-interaction inverter, MPC of a capacitor-less VAR compensator based on matrix converter (MC). This dissertation firstly investigates a multi-objective optimization technique for a hybrid distribution system. The variability of a high-penetration PV scenario is also studied when incorporated into the microgrid concept. Emerging (PV) technologies have enabled the creation of contoured and conformal PV surfaces; the effect of using non-planar PV modules on variability is also analyzed. The proposed predictive control to achieve maximum power point for isolated and grid-tied PV systems speeds up the control loop since it predicts error before the switching signal is applied to the converter. The low conversion efficiency of PV cells means we want to ensure always operating at maximum possible power point to make the system economical. Thus the proposed MPPT technique can capture more energy compared to the conventional MPPT techniques from same amount of installed solar panel. Because of the MPPT requirement, the output voltage of the converter may vary. Therefore a droop control is needed to feed multiple arrays of photovoltaic systems to a DC bus in microgrid community. Development of a droop control technique by means of predictive control is another application of this dissertation. Reactive power, denoted as Volt Ampere Reactive (VAR), has several undesirable consequences on AC power system network such as reduction in power transfer capability and increase in

  2. Design and control of a standalone PV water pumping system

    Directory of Open Access Journals (Sweden)

    Essam E. Aboul Zahab

    2017-09-01

    Full Text Available Water resources are vital for satisfying human needs. However, almost one-fifth of the world’s population – about 1.2 billion people – live in areas where water is physically rare. One quarter of the global population also live in developing countries that face water shortages. This paper presents standalone PV water pumping system. Photovoltaic (PV is the main power source, and lead acid batteries are used as energy storage system, to supply a water pump driven by a BLDC motor. The proposed control strategy consists of three control units. The first unit is to control the speed and hysteresis current controller for BLDC motor. The maximum power point tracking (MPPT is the second control unit, and the battery charging/discharging system is controlled by the third controller. The simulation results show the effectiveness and the good efficiency of the proposed system.

  3. Adaptive maximum power point tracking control of fuel cell power plants

    Science.gov (United States)

    Zhong, Zhi-dan; Huo, Hai-bo; Zhu, Xin-jian; Cao, Guang-yi; Ren, Yuan

    A fuel cell's output power depends nonlinearly on the applied current or voltage, and there exists a unique maximum power point (MPP). This paper reports a first attempt to trace MPPs by an extremum seeking controller. The locus of MPPs varies nonlinearly with the unpredictable variations in the fuel cell's operation conditions. Thus, a maximum power point tracking (MPPT) controller is needed to continuously deliver the highest possible power to the load when variations in operation conditions occur. A two-loop cascade controller with an intermediate converter is designed to operate fuel cell power plants at their MPPs. The outer loop uses an adaptive extremum seeking algorithm to estimate the real-time MPP, and then gives the estimated value to the inner loop as the set-point, at which the inner loop forces the fuel cell to operate. The proposed MPPT control system provides a simple and robust control law that can keep the fuel cell working at MPPs in real time. Simulation shows that this control approach can yield satisfactory results in terms of robustness toward variations in fuel cell operation conditions.

  4. Controllers for Battery Chargers and Battery Chargers Therefrom

    Science.gov (United States)

    Elmes, John (Inventor); Kersten, Rene (Inventor); Pepper, Michael (Inventor)

    2014-01-01

    A controller for a battery charger that includes a power converter has parametric sensors for providing a sensed Vin signal, a sensed Vout signal and a sensed Iout signal. A battery current regulator (BCR) is coupled to receive the sensed Iout signal and an Iout reference, and outputs a first duty cycle control signal. An input voltage regulator (IVR) receives the sensed Vin signal and a Vin reference. The IVR provides a second duty cycle control signal. A processor receives the sensed Iout signal and utilizes a Maximum Power Point Tracking (MPPT) algorithm, and provides the Vin reference to the IVR. A selection block forwards one of the first and second duty cycle control signals as a duty cycle control signal to the power converter. Dynamic switching between the first and second duty cycle control signals maximizes the power delivered to the battery.

  5. Exploration of two methods for quantitative Mitomycin C measurement in tumor tissue in vitro and in vivo

    DEFF Research Database (Denmark)

    Fischer, Lee MacKenzie; Vásquez, Juan Luis; Gehl, Julie

    2013-01-01

    Two methods of quantifying Mitomycin C in tumor tissue are explored. A method of ultraviolet-visible absorption microscopy is developed and applied to measure the concentration of Mitomycin C in preserved mouse tumor tissue, as well as in gelatin samples. Concentrations as low as 60 μM can...... is fed to a flow cell to determine intratumor concentrations in real time to within a few μM. The success and limitations of these techniques are identified, and suggestions are made as to further development. To the authors’ knowledge these are the first attempts made to quantify Mitomycin C...

  6. Two Methods of Automatic Evaluation of Speech Signal Enhancement Recorded in the Open-Air MRI Environment

    Science.gov (United States)

    Přibil, Jiří; Přibilová, Anna; Frollo, Ivan

    2017-12-01

    The paper focuses on two methods of evaluation of successfulness of speech signal enhancement recorded in the open-air magnetic resonance imager during phonation for the 3D human vocal tract modeling. The first approach enables to obtain a comparison based on statistical analysis by ANOVA and hypothesis tests. The second method is based on classification by Gaussian mixture models (GMM). The performed experiments have confirmed that the proposed ANOVA and GMM classifiers for automatic evaluation of the speech quality are functional and produce fully comparable results with the standard evaluation based on the listening test method.

  7. Comparative Examination of Capercaillie (Tetrao urogallus L. Behaviour Responses and Semen Quality to Two Methods of Semen Collection.

    Directory of Open Access Journals (Sweden)

    Ewa Teresa Łukaszewicz

    Full Text Available Artificial insemination (AI is very helpful in solving the reproductive and biodiversity problems observed in small, closed avian populations. The successful production of fertilized eggs using AI is dependent on the collection of good quality semen. Two methods of male sexual stimulation and semen collection from captive kept capercaillie (Tetrao urogallus L., one of the most seriously endangered grouse species in Europe, are compared in this study. Ejaculates were obtained either with the use of a dummy female or by the dorso-abdominal massage method. Differences in the individual responses of the males to the two methods of semen collection as well as in their semen quality were noted. Only sperm concentration (432.4 x 10(6 mL(-1 with dummy female and 614.5 x 10(6 mL(-1 for massage method was significantly affected by capercaillie stimulation method. Sperm motility and morphology were not affected (P ≥ 0.05. Thus, for semen collection from captive kept capercaillie both methods can be used successfully. The dummy female can be an alternative to dorso-abdominal massage method, commonly used for semen collection from domesticated bird species.

  8. A comparison of two methods of measuring static coefficient of friction at low normal forces: a pilot study.

    Science.gov (United States)

    Seo, Na Jin; Armstrong, Thomas J; Drinkaus, Philip

    2009-01-01

    This study compares two methods for estimating static friction coefficients for skin. In the first method, referred to as the 'tilt method', a hand supporting a flat object is tilted until the object slides. The friction coefficient is estimated as the tangent of the angle of the object at the slip. The second method estimates the friction coefficient as the pull force required to begin moving a flat object over the surface of the hand, divided by object weight. Both methods were used to estimate friction coefficients for 12 subjects and three materials (cardboard, aluminium, rubber) against a flat hand and against fingertips. No differences in static friction coefficients were found between the two methods, except for that of rubber, where friction coefficient was 11% greater for the tilt method. As with previous studies, the friction coefficients varied with contact force and contact area. Static friction coefficient data are needed for analysis and design of objects that are grasped or manipulated with the hand. The tilt method described in this study can easily be used by ergonomic practitioners to estimate static friction coefficients in the field in a timely manner.

  9. Control of a Multi-Functional Inverter for Grid Integration of PV and Battery Energy Storage System

    DEFF Research Database (Denmark)

    Mousazadeh, Seyyed Yousef; Firoozabadi, Mehdi Savaghebi; Beirami, A.

    2015-01-01

    power point tracking (MPPT) of PV array. The power system is 3-phase 4-wires and the DC/AC inverter is chosen 4-leg three phase inverter which has good performance in presence of zero sequence components. Battery energy storage is connected to PV system in common DC bus and a power management strategy......This paper presents a multi-functional control of a DC/AC inverter for Power Quality compensation of nonlinear and unequal local loads and grid integration of hybrid photovoltaic (PV) and battery energy storage systems. Multi-layer neural network estimator and a DC/DC converter are used for maximum...

  10. Hierarchical control of a photovoltaic/battery based DC microgrid including electric vehicle wireless charging station

    DEFF Research Database (Denmark)

    Xiao, Zhao xia; Fan, Haodong; Guerrero, Josep M.

    2017-01-01

    In this paper, the hierarchical control strategy of a photovoltaic/battery based dc microgrid is presented for electric vehicle (EV) wireless charging. Considering irradiance variations, battery charging/discharging requirements, wireless power transmission characteristics, and onboard battery...... charging power change and other factors, the possible operation states are obtained. A hierarchical control strategy is established, which includes central and local controllers. The central controller is responsible for the selection and transfer of operation states and the management of the local...... controllers. Local controllers implement these functions, which include PV maximum power point tracking (MPPT) algorithm, battery charging/discharging control, voltage control of DC bus for high-frequency inverter, and onboard battery charging control. By optimizing and matching parameters of transmitting...

  11. Tip Speed Ratio Based Maximum Power Tracking Control of Variable Speed Wind Turbines; A Comprehensive Design

    Directory of Open Access Journals (Sweden)

    Murat Karabacak

    2017-08-01

    Full Text Available The most primitive control method of wind turbines used to generate electric energy from wind is the fixed speed control method. With this method, it is not possible that turbine input power is transferred to grid at maximum rate. For this reason, Maximum Power Tracking (MPT schemes are proposed. In order to implement MPT, the propeller has to rotate at a different speed for every different wind speed. This situation has led MPT based systems to be called Variable Speed Wind Turbine (VSWT systems. In VSWT systems, turbine input power can be transferred to grid at rates close to maximum power. When MPT based control of VSWT systems is the case, two important processes come into prominence. These are instantaneously determination and tracking of MPT point. In this study, using a Maximum Power Point Tracking (MPPT method based on tip speed ratio, power available in wind is transferred into grid over a back to back converter at maximum rate via a VSWT system with permanent magnet synchronous generator (PMSG. Besides a physical wind turbine simulator is modelled and simulated. Results show that a time varying MPPT point is tracked with a high performance.

  12. Comparison of two methods of γ-radiation disturbance removal in β-radioactive surface contamination measurement

    International Nuclear Information System (INIS)

    Zhao Fei; Sun Yanze; Wen Wanxin

    2011-01-01

    Objective: To study two methods' effectiveness of removing the γ-interference in β-surface contamination measurement. Methods: Masking and distancing were used alternately in the measurements of several radioactive sources and workshop ground surface. The meter counts difference was compared before and after the methods separately, we can infer whether γ-interference exists. Results: If interference exists, there is remarkable difference after using masking (P<0.01), and that difference also appears after using distancing (P<0.01), but not all situation. Conclusion: Masking can be taken as an effective method to judge the validity of measured data qualitatively and quickly, furthermore, to give recommendations to the next step. As for the method of distancing, the scope of its application is confined only in the homogeneous γ-radiation field; otherwise the method is inadvisable. (authors)

  13. Study of the optical properties of CuAlS2 thin films prepared by two methods

    Science.gov (United States)

    Ahmad, S. M.

    2017-04-01

    CuAlS2 thin films were successfully deposited on glass substrates using two methods: chemical spray pyrolysis (CSP) and chemical bath deposition (CBD). It was confirmed from the X-ray diffraction (XRD) analysis that CSP films exhibited a polycrystalline nature while amorphous nature was diagnosed for CBD films. Also XRD analysis was utilized to compute grain size, strain and dislocation density. Surface morphology was characterized using scanning electron microscope and photomicroscope images. The optical absorption measurement revealed that the direct allowed electronic transition with band gaps 2.8 eV and 3.0 eV for CBD and CSP methods, respectively. The optical constants, such as extinction coefficient ( k), refractive index ( n), real and imaginary dielectric constants ( ɛ 1, ɛ 2) were discussed. The photoluminescence (PL) spectra of CuAlS2 thin films appeared as a single peak for each of them, and this is attributed to band-to-band transition.

  14. Comparison of Two Methods for Analysis of GxE Interactions in Longitudinal Family Data: The Framingham Heart Study

    Directory of Open Access Journals (Sweden)

    Yun Ju eSung

    2014-01-01

    Full Text Available GxE interaction analysis can potentially enhance gene discovery for common complex traits. However, genome-wide interaction analysis (GWIS is computationally intensive. Moreover, analysis of longitudinal data in families is much more challenging due to the two sources of correlations arising from longitudinal measurements and family relationships. GWIS of longitudinal family data can be a computational bottleneck. Therefore, we compared two methods for analysis of longitudinal family data: a methodologically sound but computationally demanding method using the Kronecker Model (KRC and a computationally more forgiving method using the Hierarchical Linear Model (HLM. The KRC model uses a Kronecker product of an unstructured matrix for correlations among repeated measures (longitudinal and a compound symmetry matrix for correlations within families at a given visit. The HLM uses an autoregressive covariance matrix for correlations among repeated measures and a random intercept for familial correlations. We compared the two methods using the longitudinal Framingham Heart Study (FHS SHARe data. Specifically, we evaluated SNP-Alcohol (amount of alcohol consumption interaction effects on HDL-cholesterol. Keeping the prohibitive computational burden of KRC in mind, we limited the analysis to chromosome 16, where preliminary cross-sectional analysis yielded some interesting results. Our first important finding was that the HLM provided very comparable results but was remarkably faster than the KRC, making HLM the method of choice. Our second finding was that longitudinal analysis provided smaller p values, thus leading to more significant results, than cross-sectional analysis. This was particularly pronounced in identifying GxE interactions. We conclude that longitudinal analysis of GxE interactions is more powerful and that the HLM method is an optimal method of choice as compared to the computationally (prohibitively intensive KRC method.

  15. Evaluation of two methods DNA extraction from formalin-fixed, paraffin-embedded tissues on non-optimal conditions

    International Nuclear Information System (INIS)

    Bustamante, Javier Andres; Astudillo, Miryam; Pazos, Alvaro Jairo; Bravo, Luis Eduardo

    2011-01-01

    Paraffin wax embedded tissues are an invaluable material for retrospective studies requiring the application of molecular analysis. Multiple methods are available to extract DNA from these kinds of samples. However, the most common methods are slow and the reagents often contribute to the fragmentation of genetic material. In order to optimize the procedure, two methods for DNA extraction from paraffin embedded tissue non-optimal conditions were used. 47 blocks containing paraffin-embedded biopsies of pleura, lung and pericardium from 24 patients (66.6% males) older than 18 years, with biopsy proven chronic granulomatous inflammation referred to the department of pathology at University Hospital of Valle between 2002 and 2007 were selected. Each sample was subjected to 10 cuts and was to two methods of DNA extraction: 1. conventional and 2. QIAamp - DNA mini kit. The efficiency of the extracted DNA was assessed by spectrophotometry and PCR amplification of a fragment of the housekeeping gene GAPDH. The concentration of DNA samples extracted by the conventional method was of 65.52 ng/Mu l ± 11.47 (mean ± SE) and the 260/280 absorbance ratio ranged between 0.52 and 2.30 the average concentration of DNA of the samples extracted by the commercial method was 60.89 ng/Mu l ± 6.02 (mean ± SE), with an absorbance that fluctuated between 0 and 2.64. The DNA obtained was amplified by PCR, of 47 samples extracted by methods, 25 and 23 respectively the GAPDH gene amplified successfully. The methods used to obtain DNA showed similar performance, highlighting the potential utility of both extraction methods for the retrospective studies from paraffin embedded tissues in unsuitable conditions.

  16. Energy Management and Control of Plug-In Hybrid Electric Vehicle Charging Stations in a Grid-Connected Hybrid Power System

    Directory of Open Access Journals (Sweden)

    Sidra Mumtaz

    2017-11-01

    Full Text Available The charging infrastructure plays a key role in the healthy and rapid development of the electric vehicle industry. This paper presents an energy management and control system of an electric vehicle charging station. The charging station (CS is integrated to a grid-connected hybrid power system having a wind turbine maximum power point tracking (MPPT controlled subsystem, photovoltaic (PV MPPT controlled subsystem and a controlled solid oxide fuel cell with electrolyzer subsystem which are characterized as renewable energy sources. In this article, an energy management system is designed for charging and discharging of five different plug-in hybrid electric vehicles (PHEVs simultaneously to fulfil the grid-to-vehicle (G2V, vehicle-to-grid (V2G, grid-to-battery storage system (G2BSS, battery storage system-to-grid (BSS2G, battery storage system-to-vehicle (BSS2V, vehicle-to-battery storage system (V2BSS and vehicle-to-vehicle (V2V charging and discharging requirements of the charging station. A simulation test-bed in Matlab/Simulink is developed to evaluate and control adaptively the AC-DC-AC converter of non-renewable energy source, DC-DC converters of the storage system, DC-AC grid side inverter and the converters of the CS using adaptive proportional-integral-derivate (AdapPID control paradigm. The effectiveness of the AdapPID control strategy is validated through simulation results by comparing with conventional PID control scheme.

  17. Efficient design and simulation of an expandable hybrid (wind-photovoltaic) power system with MPPT and inverter input voltage regulation features in compliance with electric grid requirements

    Energy Technology Data Exchange (ETDEWEB)

    Skretas, Sotirios B.; Papadopoulos, Demetrios P. [Electrical Machines Laboratory, Department of Electrical and Computer Engineering, Democritos University of Thrace (DUTH), 12 V. Sofias, 67100 Xanthi (Greece)

    2009-09-15

    In this paper an efficient design along with modeling and simulation of a transformer-less small-scale centralized DC - bus Grid Connected Hybrid (Wind-PV) power system for supplying electric power to a single phase of a three phase low voltage (LV) strong distribution grid are proposed and presented. The main components of the hybrid system are: a PV generator (PVG); and an array of horizontal-axis, fixed-pitch, small-size, variable-speed wind turbines (WTs) with direct-driven permanent magnet synchronous generator (PMSG) having an embedded uncontrolled bridge rectifier. An overview of the basic theory of such systems along with their modeling and simulation via Simulink/MATLAB software package are presented. An intelligent control method is applied to the proposed configuration to simultaneously achieve three desired goals: to extract maximum power from each hybrid power system component (PVG and WTs); to guarantee DC voltage regulation/stabilization at the input of the inverter; to transfer the total produced electric power to the electric grid, while fulfilling all necessary interconnection requirements. Finally, a practical case study is conducted for the purpose of fully evaluating a possible installation in a city site of Xanthi/Greece, and the practical results of the simulations are presented. (author)

  18. A Flexible Maximum Power Point Tracking Control Strategy Considering Both Conversion Efficiency and Power Fluctuation for Large-inertia Wind Turbines

    Directory of Open Access Journals (Sweden)

    Hongmin Meng

    2017-07-01

    Full Text Available In wind turbine control, maximum power point tracking (MPPT control is the main control mode for partial-load regimes. Efficiency potentiation of energy conversion and power smoothing are both two important control objectives in partial-load regime. However, on the one hand, low power fluctuation signifies inefficiency of energy conversion. On the other hand, enhancing efficiency may increase output power fluctuation as well. Thus the two objectives are contradictory and difficult to balance. This paper proposes a flexible MPPT control framework to improve the performance of both conversion efficiency and power smoothing, by adaptively compensating the torque reference value. The compensation was determined by a proposed model predictive control (MPC method with dynamic weights in the cost function, which improved control performance. The computational burden of the MPC solver was reduced by transforming the cost function representation. Theoretical analysis proved the good stability and robustness. Simulation results showed that the proposed method not only kept efficiency at a high level, but also reduced power fluctuations as much as possible. Therefore, the proposed method could improve wind farm profits and power grid reliability.

  19. Indirect adaptive soft computing based wavelet-embedded control paradigms for WT/PV/SOFC in a grid/charging station connected hybrid power system.

    Directory of Open Access Journals (Sweden)

    Sidra Mumtaz

    Full Text Available This paper focuses on the indirect adaptive tracking control of renewable energy sources in a grid-connected hybrid power system. The renewable energy systems have low efficiency and intermittent nature due to unpredictable meteorological conditions. The domestic load and the conventional charging stations behave in an uncertain manner. To operate the renewable energy sources efficiently for harvesting maximum power, instantaneous nonlinear dynamics should be captured online. A Chebyshev-wavelet embedded NeuroFuzzy indirect adaptive MPPT (maximum power point tracking control paradigm is proposed for variable speed wind turbine-permanent synchronous generator (VSWT-PMSG. A Hermite-wavelet incorporated NeuroFuzzy indirect adaptive MPPT control strategy for photovoltaic (PV system to extract maximum power and indirect adaptive tracking control scheme for Solid Oxide Fuel Cell (SOFC is developed. A comprehensive simulation test-bed for a grid-connected hybrid power system is developed in Matlab/Simulink. The robustness of the suggested indirect adaptive control paradigms are evaluated through simulation results in a grid-connected hybrid power system test-bed by comparison with conventional and intelligent control techniques. The simulation results validate the effectiveness of the proposed control paradigms.

  20. Indirect adaptive soft computing based wavelet-embedded control paradigms for WT/PV/SOFC in a grid/charging station connected hybrid power system.

    Science.gov (United States)

    Mumtaz, Sidra; Khan, Laiq; Ahmed, Saghir; Bader, Rabiah

    2017-01-01

    This paper focuses on the indirect adaptive tracking control of renewable energy sources in a grid-connected hybrid power system. The renewable energy systems have low efficiency and intermittent nature due to unpredictable meteorological conditions. The domestic load and the conventional charging stations behave in an uncertain manner. To operate the renewable energy sources efficiently for harvesting maximum power, instantaneous nonlinear dynamics should be captured online. A Chebyshev-wavelet embedded NeuroFuzzy indirect adaptive MPPT (maximum power point tracking) control paradigm is proposed for variable speed wind turbine-permanent synchronous generator (VSWT-PMSG). A Hermite-wavelet incorporated NeuroFuzzy indirect adaptive MPPT control strategy for photovoltaic (PV) system to extract maximum power and indirect adaptive tracking control scheme for Solid Oxide Fuel Cell (SOFC) is developed. A comprehensive simulation test-bed for a grid-connected hybrid power system is developed in Matlab/Simulink. The robustness of the suggested indirect adaptive control paradigms are evaluated through simulation results in a grid-connected hybrid power system test-bed by comparison with conventional and intelligent control techniques. The simulation results validate the effectiveness of the proposed control paradigms.

  1. Indirect adaptive soft computing based wavelet-embedded control paradigms for WT/PV/SOFC in a grid/charging station connected hybrid power system

    Science.gov (United States)

    Khan, Laiq; Ahmed, Saghir; Bader, Rabiah

    2017-01-01

    This paper focuses on the indirect adaptive tracking control of renewable energy sources in a grid-connected hybrid power system. The renewable energy systems have low efficiency and intermittent nature due to unpredictable meteorological conditions. The domestic load and the conventional charging stations behave in an uncertain manner. To operate the renewable energy sources efficiently for harvesting maximum power, instantaneous nonlinear dynamics should be captured online. A Chebyshev-wavelet embedded NeuroFuzzy indirect adaptive MPPT (maximum power point tracking) control paradigm is proposed for variable speed wind turbine-permanent synchronous generator (VSWT-PMSG). A Hermite-wavelet incorporated NeuroFuzzy indirect adaptive MPPT control strategy for photovoltaic (PV) system to extract maximum power and indirect adaptive tracking control scheme for Solid Oxide Fuel Cell (SOFC) is developed. A comprehensive simulation test-bed for a grid-connected hybrid power system is developed in Matlab/Simulink. The robustness of the suggested indirect adaptive control paradigms are evaluated through simulation results in a grid-connected hybrid power system test-bed by comparison with conventional and intelligent control techniques. The simulation results validate the effectiveness of the proposed control paradigms. PMID:28877191

  2. Coordinated Control Strategies for a Permanent Magnet Synchronous Generator Based Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Ramji Tiwari

    2017-09-01

    Full Text Available In this paper, a novel co-ordinated hybrid maximum power point tracking (MPPT-pitch angle based on a radial basis function network (RBFN is proposed for a variable speed variable pitch wind turbine. The proposed controller is used to maximise output power when the wind speed is low and optimise the power when the wind speed is high. The proposed controller provides robustness to the nonlinear characteristic of wind speed. It uses wind speed, generator speed, and generator power as input variables and utilises the duty cycle and the reference pitch angle as the output control variables. The duty cycle is used to control the converter so as to maximise the power output and the reference pitch angle is used to control the generator speed in order to control the generator output power in the above rated wind speed region. The effectiveness of the proposed controller was verified using MATLAB/Simulink software.

  3. Design of a nonlinear backstepping control strategy of grid interconnected wind power system based PMSG

    Science.gov (United States)

    Errami, Y.; Obbadi, A.; Sahnoun, S.; Benhmida, M.; Ouassaid, M.; Maaroufi, M.

    2016-07-01

    This paper presents nonlinear backstepping control for Wind Power Generation System (WPGS) based Permanent Magnet Synchronous Generator (PMSG) and connected to utility grid. The block diagram of the WPGS with PMSG and the grid side back-to-back converter is established with the dq frame of axes. This control scheme emphasises the regulation of the dc-link voltage and the control of the power factor at changing wind speed. Besides, in the proposed control strategy of WPGS, Maximum Power Point Tracking (MPPT) technique and pitch control are provided. The stability of the regulators is assured by employing Lyapunov analysis. The proposed control strategy for the system has been validated by MATLAB simulations under varying wind velocity and the grid fault condition. In addition, a comparison of simulation results based on the proposed Backstepping strategy and conventional Vector Control is provided.

  4. Comparing the Effect of Two Methods of Acupressure and Ice Massage on the Pain, Anxiety Levels and Labor Length in the Point LI-4

    Directory of Open Access Journals (Sweden)

    MJ Hadian Fard

    2012-06-01

    Full Text Available Introduction: Delivery is one of the most painful experiences to women throughout life; therefore, it seems essential to obtain remedies for labor pain relief, especially in regard to non-invasive methods. This study intends to compare effect of two methods of acupressure and ice massage on the pain severity, anxiety level and length of labor in nulliparous women Methods: In this experimental study, 165 nulliparous women were randomly assigned to three groups. First group: acupressure, Group II: ice massage, and group III: control. Each group consisted of 55 women. Intervention was exerted in cervical dilatation of 3-4 cm on LI-4 and intervention period lasted for 30 minutes. In the first group pressure and in the second group ice massage was applied. Labor pain and anxiety levels in the three groups were assessed by VAS and Spielberger state questionnaire in two stages. Duration of first and second stage of labor was compared in the three groups. Results: There was a significant decrease in pain immediately after intervention in ice massage and acupressure groups in comparison to the control group (P≤0/001. Moreover, pain was decreased more in the ice massage group, whereas pain intensity was increased in the control group (P≤0/001. Anxiety level and the length of first and second stage of labor were significantly reduced (P≤0/001 in comparison with the control group. Conclusion: Both acupressure and ice massage lead to reduce pain intensity, duration of labor and level anxiety in nulliparous women, the ice massage appeared to be more influential

  5. Caliper vs. Lipometer--Comparing Two Methods of Subcutaneous Body Fat Measurement by Bland-Altman Diagrams.

    Science.gov (United States)

    Tafeit, Erwin; Kaimbacher, Petra Silke; Wallner-Liebmann, Sandra Johanna; Reibnegger, Gilbert; Cvirn, Gerhard; Jürimäe, Jaak; Saar, Meeli; Maestu, Jarek; Purge, Priit; Lätt, Evelin; Jürimäe, Toivo

    2015-09-01

    Skinfold Calipers are widely used to obtain subcutaneous adipose tissue thickness because of its non-invasive, simple and inexpensive technique. Nevertheless, Caliper skinfold thicknesses have the disadvantage of measuring compressed adipose tissue and double layers of skin, which might reduce the precision of these results. In contrast, the computerized optical device Lipometer was developed to permit a quick, precise and non-invasive determination of non-compressed mono layers of subcutaneous adipose tissue thickness. In the present paper we investigate the hypothesis that Caliper skinfold thicknesses are significantly different from subcutaneous adipose tissue thicknesses in mm, which can be measured by Lipometer. Caliper and Lipometer results were obtained from 371 Estonian boys aged between 9.0 and 12.8 years. Measurements were performed at six different body sites: triceps, biceps, upper back, upper abdomen, hip and front thigh. Caliper measurements were systematically higher than Lipometer results in a range between 1.2 mm (hip) and 11.08 mm (front thigh). The limits of agreement analysis provided intervals from 7.5 mm (biceps) up to 30.14 mm (front thigh). Comparing Caliper and Lipometer results very low measurement agreement was found. The two methods provided very poor interchangeability.

  6. Serological diagnosis of infections sustained by Toxoplasma gondii, Rubella virus and Citomegalovirus, a comparison between two methods

    Directory of Open Access Journals (Sweden)

    Marco Moretti

    2009-12-01

    Full Text Available The serological diagnosis of infections from Toxoplasma gondii, Rubella virus and Cytomegalovirus is of a great importance especially during pregnancy for the risk of maternal-fetal infections. Serological testing have evolved with time and are many on the market with different levels of specificity and sensivity. The aim of the study was to determine the analytical and clinical concordance between two methods for the determination of specific IgG and IgM antibodies against T. gondii, Rubella virus and Cytomegalovirus. The total numbers of samples evaluated for T. gondii, Rubella virus and Cytomegalovirus IgG and IgM were 124 and 127, 83 and 87, 129 and 103, respectively. The comparison methods used for this study were Diamedix® enzime imunoassay run in MAGO-Plus Delta Biologicals® Immunodiagnostics System (routinely used and Vitros© Eci chemiluminescence immunoassay run in Vitros ECiQ Immunodiagnostics System ORTHO-Clinical Diagnostics Johnson & Johnson company.Vidas bioMérieux was take as referee method to evaluate discrepant results. Analytical concordance ranged between 87 and 97%, clinical concordance ranged between 93 and 99%. Despite differences in detection antibodies (specific IgG and IgM and revelation of signal the methods evaluated show generally good levels of clinical concordance.The results are consistent with references and External Quality Assurance Programs.

  7. Impact evaluation of two methods of dental health education among children of a primary school in rural India

    Directory of Open Access Journals (Sweden)

    Neha Singh

    2016-01-01

    Full Text Available Background: Impact of two methods of dental health education (DHE on knowledge and practices of primary school children in a rural area regarding oral care was planned to be studied. Materials and Methods: Study population comprised of 199 primary school children aged 10-13 years in rural field practice area of a medical college. After collecting baseline data, students were allocated into two groups by block randomization using variable blocks. DHE with educational pamphlets and demonstrations was given to both groups. In addition, the intervention group was also shown videos showing correct oral health practices. Data were proposed to be collected at 3 and 6 months from baseline for impact evaluation. The results at 3 months postintervention are being presented. Results: The results after 3 months of intervention found significant difference in the impact on: (a Practices regarding method of cleaning teeth (P < 0.001, (b knowledge on best method of cleaning teeth (P < 0.001, (c reason for regular brushing of teeth (P < 0.001, and (d requirement to clean teeth after eating something sweet (P < 0.001 in favor of group receiving additional intervention. Conclusion: There is a significant difference in the impact of health education using integrated modes of pamphlets distribution, demonstrations, and A-V aids (group A as compared to demonstrations and pamphlets distribution only (group B.

  8. Microprocessor-controlled step-down maximum-power-point tracker for photovoltaic systems

    Science.gov (United States)

    Mazmuder, R. K.; Haidar, S.

    1992-12-01

    An efficient maximum power point tracker (MPPT) has been developed and can be used with a photovoltaic (PV) array and a load which requires lower voltage than the PV array voltage to be operated. The MPPT makes the PV array to operate at maximum power point (MPP) under all insolation and temperature, which ensures the maximum amount of available PV power to be delivered to the load. The performance of the MPPT has been studied under different insolation levels.

  9. Power Maximization Control of Variable Speed Wind Generation System Using Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Morimoto, Shigeo; Nakamura, Tomohiko; Takeda, Yoji

    This paper proposes the sensorless output power maximization control of the wind generation system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. The generator torque is suitably controlled according to the generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control method, where the information of wind velocity is not required. Moreover, the maximum available generated power is obtained by the optimum current vector control. The current vector of PMSG is optimally controlled according to the generator speed and the required torque in order to minimize the losses of PMSG considering the voltage and current constraints. The proposed wind power generation system can be achieved without mechanical sensors such as a wind velocity detector and a position sensor. Several experimental results show the effectiveness of the proposed control method.

  10. Maximum Power Point Tracking Sensorless Control of an Axial-Flux Permanent Magnet Vernier Wind Power Generator

    Directory of Open Access Journals (Sweden)

    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.

  11. A comparison of two methods of determining colour change in the assessment of the quality of pork.

    Science.gov (United States)

    Karamucki, Tadeusz; Rybarczyk, Artur; Jakubowska, Małgorzata; Sulerzycka, Anna

    2017-01-01

    The colour of pork is one of the most important measures of meat quality. For the consumer, it is a sign of freshness, crucial for the decision to buy a product. The storage of meat results in constant col- our changes. Differences can be found in all colour parameters, especially chromatic ones, such as redness (a*) and hue angle (h°), as these changes are significantly correlated with a number of quality traits. Colour change can be determined not only by evaluating changes in colour parameters, but also by establishing the change in absorbance of specific wavelengths of light. The aim of this study was to compare the usefulness of these two methods of determining colour change: parameters measured on the CIELAB and CIELCh scales and colour change (%CC) determined based on the absorbance of selected wavelengths of light, i.e. 505, 540, 560, 580 and 630 nm. In this paper, we analysed two methods of measuring colour change in terms of their relevance for meat quality assessment. The study involved 150 samples of the longissimus lumborum muscle collected from 150 carcasses of pigs slaughtered on an industrial line, weighing 65-107 kg, with an average carcass weight of 86.1 kg. Meat sensory analysis (colour, wateriness, firmness), physicochemical assessment (colour, WHC, pH48) and proximate analysis (moisture, total protein, fat, ash) were carried out. The methods included the determination of (I) changes in colour parameters measured on the CIELAB and CIELCh scales, and (II) colour change (%CC) based on the absorbance of selected wavelengths: 505, 540, 560, 580 and 630 nm. Chromatic absorbance values of a wavelength of 525 nm (A525p) and the relative content of Mb, MbO2 and MetMb were calculated according to the method proposed by Krzywicki (1979). Basic chemical composition - with few exceptions - was not significantly correlated with differenc- es in the values of colour parameters (ΔL*, ?a*, ?b*, ΔC*, Δh°) and colour change (%CC). With an increase in scores

  12. Comparison of Two Methods of Ruminal Digestibility Determination (in situ and in vitro of Pomegranate Seed Pulp

    Directory of Open Access Journals (Sweden)

    Mohammad Hassan Fathi Nasri

    2016-08-01

    Full Text Available Introduction Using of agro-industrial by-products in diet of livestock not only reduces the production costs but also can dwindle the use of human foods in animal nutrition and competition between human and livestock. Thus, proper use of these by-products in animal nutrition and identification of new and low cost feed resources may be one of the priorities in livestock husbandry of our country. Pomegranate seed pulp (PSP is a by-product of the industrial decoction of pomegranate. Iran with annually production of more than 900 tons of pomegranates is one of the most important regions of pomegranate cultivation and PSP produced from pomegranate processing factories may be extensively used in animal nutrition. Digestibility determination of feeds is one of the most effective ways to evaluate their nutritional value. In addition, there is a strong relationship between feeds digestibility and performance of animal. There are in vivo, in vitro and in situ methods to determine the digestibility of feeds. Although in vivo methods are reference for digestibility values of feeds and are of high precision but they are usually expensive and time consuming. In addition, these methods do not provide any information related to ruminal degradability kinetic of nutrients. The aim of this study was comparison of two methods of ruminal degradability determination methods namely, in situ (nylon bag and in vitro (Daisy incubator, using dried and ensiled pomegranate seed pulp (PSP. Materials and Methods The PSP used in this study was prepared from Anaryan Co. in Ferdows, Iran. Decocted pomegranate was a mixture of Yazd varieties which were harvested at early autumn of 1389. Two types of PSP as dried and ensiled were used to compare the methods of ruminal digestibility determination, pervasively. The PSP silage was prepared by ensiling of wet PSP (containing 475 g/kg DM in 3 kg bins (4 replicatesand with density of 650 kg wet PSP per cubic meter for 60 days and dried

  13. Two-method measurement for adolescent obesity epidemiology: reducing the bias in self-report of height and weight.

    Science.gov (United States)

    Drake, Keith M; Longacre, Meghan R; Dalton, Madeline A; Langeloh, Gail; Peterson, Karen E; Titus, Linda J; Beach, Michael L

    2013-09-01

    Despite validation studies demonstrating substantial bias, epidemiologic studies typically use self-reported height and weight as primary measures of body mass index because of feasibility and resource limitations. To demonstrate a method for calculating accurate and precise estimates that use body mass index when objectively measuring height and weight in a full sample is not feasible. As part of a longitudinal study of adolescent health, 1,840 adolescents (ages 12-18) self-reported their height and weight during telephone surveys. Height and weight was measured for 407 of these adolescents. Sex-specific, age-adjusted obesity status was calculated from self-reported and from measured height and weight. Prevalence and predictors of obesity were estimated using self-reported data, measured data, and multiple imputation (of measured data). Among adolescents with self-reported and measured data, the obesity prevalence was lower when using self-report compared with actual measurements (p obesity prevalence from multiple imputation (20%) was much closer to estimates based solely on measured data (20%) compared with estimates based solely on self-reported data (12%), indicating improved accuracy. In multivariate models, estimates of predictors of obesity were more accurate and approximately as precise (similar confidence intervals) as estimates based solely on self-reported data. The two-method measurement design offers researchers a technique to reduce the bias typically inherent in self-reported height and weight without needing to collect measurements on the full sample. This technique enhances the ability to detect real, statistically significant differences, while minimizing the need for additional resources. Copyright © 2013 Society for Adolescent Health and Medicine. All rights reserved.

  14. The Comparison between Two Methods for the Relief of Knee Osteoarthritis Pain: Radiofrequency and Intra-Periarticular Ozone Injection: A Clinical Trial Study

    Directory of Open Access Journals (Sweden)

    Masoud Hashemi

    2016-07-01

    Full Text Available Knee osteoarthritis is not always well controlled by usual treatments, therefore new therapeutic methods such as radiofrequency and ozone injection should be investigated. Comparing the efficacy of two methods: radiofrequency and intra-periarticular ozone injection. This randomized clinical trial study was performed in an academic Pain Clinic of Guilan University of Medical Sciences in Iran from September 2014 to June 2015. The research was carried out on seventy-two patients, were randomly allocated in two groups by triple blocks. thirty-six patients in ozone group received intra-periarticular ozone injection and 36 patients in RF group, after a positive diagnostic genicular nerve blocks received Conventional Radiofrequency(CRFand then intra articular Pulse Radiofrequency(PRF. The evaluation was based on Visual Analog Scale (VAS and Oxford Knee Score (OKS before and 12 weeks after the procedure. The analysis was performed by paired t-test, Fisher, Chi square and Mann-Whitney-U tests in SPSS version18. In Ozone group the mean of initial OKS was 38.77±7.75 compare to 41.22±7.44 in RF group. After 12 weeks, it diminish ed to 21.77±7.78 and 22±6.21 respectively (p=0.0001 . In Ozone group VAS decreased from 9±1.43 to 3.38±1.79 (p=0.0001 while in RF group from 9.44±0.85 to 2.77±1.06 (p=0.0001. Comparing two methods, there was no significant difference between two groups based on OKS(p=0.23 and VAS (p=0.202. Also RF resulted in more acceptable pain relief based on OKS among subjects older than 65 years (p=0.0001. Both radiofrequency and intra-periarticular ozone injection have good clinical effects on knee osteoarthritis with superiority of radio frequency in age above 65 years old.

  15. Sensorless Control for the EVT-Based New Dual Power Flow Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Ying Zhu

    2017-06-01

    Full Text Available The dual power flow wind energy conversion system (DPF-WECS is a novel system which is based on the electrical variable transmission (EVT machine. The proposed sensorless control for the DPF-WECS is based on the model reference adaptive system (MRAS observer by combining the sliding mode (SM theory. The SM-MRAS observer is on account of the calculations without the requirement of the proportional-integral (PI loop which exists in the classical MRAS observer. Firstly, the sensorless algorithm is applied in the maximum power point tracking (MPPT control considering the torque loss for the outer rotor of the EVT. Secondly, the sensorless control is adopted for the inner rotor control of the EVT machine. The proposed sensorless control method based on the SM-MRAS for the DPF-WECS is verified by the simulation and experimental results.

  16. Robust Controller to Extract the Maximum Power of a Photovoltaic System

    Directory of Open Access Journals (Sweden)

    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.

  17. A comparison of two methods for direct tunneling dynamics: Hydrogen exchange in the glycolate anion as a test case

    Science.gov (United States)

    Smedarchina, Zorka; Fernandez-Ramos, Antonio; Rios, Miguel A.

    1997-03-01

    Two methods for studying tunneling dynamics are compared, namely the instanton model and the approach of Truhlar and co-workers, which are based on the direct output of electronic structure calculations and thus are parameter free. They are employed to evaluate the zero-level tunneling splitting due to intramolecular hydrogen exchange in the glycolate anion. The first method was developed in a series of recent studies and presents a combination of the instanton theory with quantum-chemically computed potentials and force fields. For the compound at hand, which has 21 internal degrees of freedom, a complete potential-energy surface is generated in terms of the normal modes of the transition-state configuration. It is made up of the potential-energy curve along the tunneling coordinate and harmonic force fields at the stationary points. The level of theory used is HF/6-31++G**. All modes that are displaced between the equilibrium configuration and the transition state are linearly coupled to the tunneling mode, the couplings being proportional to the displacements in dimensionless units. These couplings affect the instanton trajectory profoundly and, depending on the symmetry of the skeletal modes, can enhance or suppress the tunneling. In the glycolate anion all modes have such displacements and thus are included in the calculation. Based on the similarity with malonaldehyde, it is argued that tunneling prevails in the studied process, and the zero-level tunneling splitting is predicted. The latter is found within the computational scheme developed earlier, which avoids explicit evaluation of the instanton path and thus greatly simpli-fies the tunneling dynamics. These results are tested by the method of large-curvature tunneling of Truhlar and co-workers implemented in a dual-level scheme. The potential energy surface needed for the dynamics calculations is generated at the semiempirical PM3 level of theory and then corrected by interpolation with high-level HF/6

  18. From lists of behaviour change techniques (BCTs) to structured hierarchies: comparison of two methods of developing a hierarchy of BCTs.

    Science.gov (United States)

    Cane, James; Richardson, Michelle; Johnston, Marie; Ladha, Ruhina; Michie, Susan

    2015-02-01

    change techniques and over 93 have been identified. Taxonomies of behaviour change techniques require structure to enable potential applications. What does this study add? This study identifies groups of BCTs to aid the recall of BCTs for intervention coding and design. It compares two methods of grouping--'bottom-up' and theory-based 'top-down'--and finds a moderate overlap. Building on identified BCT groups, it examines relationships between theoretical domains and BCTs. © 2014 The British Psychological Society.

  19. EFFECTS OF TWO METHODS OF INSTRUCTION ON STUDENTS’ CRITICAL RESPONSE TO PROSE LITERATURE TEXT IN ENGLISH IN SOME SECONDARY SCHOOLS IN BENIN CITY

    Directory of Open Access Journals (Sweden)

    F. O. EZEOKOLI

    2016-08-01

    Full Text Available This study investigated the effects of two methods of instruction on secondary school students’ critical response to Prose Literature text. The study adopted a pretest, posttest, control group quasi experimental design. The participants in the study were 84 Senior Secondary II students of Literature-in-English purposively selected from four Schools in Ikpoba-Okha Local Government Area of Edo State. Two intact classes were randomly assigned to each of the treatment and control groups. Three hypotheses were tested at 0.05 alpha level. The instruments used were: Critical Response to Prose Literature Test (r = .75, Questionnaire on Home Background of Students (r = .82, and Critical Response to Prose Literature Test Marking Guide. Data obtained were subjected to Analysis of Covariance and graph. The results showed significant main effect of treatment on students’ critical response to Prose Literature (F (1, 77 = 44.731; p < .05. Students exposed to Engagement Strategies Method performed better than those exposed to the Conventional Method of instruction. Further, home background of students had no significant effect on students’ critical response to Prose Literature text (F (2, 77 = 4.902; p < .05. There was significant interaction effect of treatment and home background of students on students’ critical response to Prose Literature text (F (2, 77 = 3.508; p < .05. It was concluded that Engagement Strategies Method is effective in promoting students’ critical response to Prose Literature text. Teachers of Literature-in-English should employ Engagement Strategies Method in teaching Prose Literature to students in Senior Secondary Schools.

  20. Qualitative and Quantitative Features Evaluation of Two Methods of Sugarcane Harvesting (with aim of Energy and Sugar Production

    Directory of Open Access Journals (Sweden)

    K Andekaeizadeh

    2018-03-01

    per hour (Mg.h-1 Chopper energy consumption in Energycane method was 1.65 KJ more than Sugarcane method. The quantitative parameters including forward speed (km.h-1, field capacity (ha.h-1, the field performance (Mg.ha-1 and reed output (Mg.h-1 were also measured. Finally, statistical comparison was conducted between the two methods. The aim of this study is to provide Simple Additive Weighting (SAW method using the calculated parameters by the Matanker et al. This method provides decision-making ability for a manager. Materials and Methods In this study, quantitative parameters including fuel consumption (Lit.ha-1, harvester power (kW, efficiency of engine torque (%, energy of used hydraulic oil in basecutter, chopper and elevator (Mj.Mg-1, forward speed (km.h-1, field capacity (ha.h-1, the field performance (Mg.ha-1 and reed output (Mg.h-1 and qualitative parameters including the mean of average diameter of the stem (mm, stem height (m, number of stems on the meter (m-1, the percentage of cut stems and intact, cut stems and partially damaged and strongly damaged stems. The average height of straw and the stubble (mm, average of bulk density (kg.m-3, the average of moisture content, average of dry matter (biomass, (Mg.ha-1 were measured. Data analysis was conducted with Simple Additive Weighting (SAW method. Tables 1 and 2 in terms of qualitative and quantitative parameters for the two methods of A and B, to form of rij matrix and based on measured criteria (C have arranged, respectively. Conclusions Choosing the appropriate method for sugarcane harvesting should be according to the purpose of harvesting. Energycane method has high energy consumption that it increases the operational costs. On the other hand, the quality of the obtained biomass from it is better, but Sugarcane method has high energy efficiency. But in terms of quality, the plant is not in good condition. For this reason, it is necessary, aim of harvesting and its type, be specified before crop

  1. Extension Sliding Mode Controller for Maximum Power Point Tracking of Hydrogen Fuel Cells

    Directory of Open Access Journals (Sweden)

    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.

  2. Maximum Power Point Tracking Based on Sliding Mode Control

    Directory of Open Access Journals (Sweden)

    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.

  3. Modeling, Simulation and Control of Wind Energy Conversion System based on Doubly Fed Induction Generator and Cycloconverter

    Directory of Open Access Journals (Sweden)

    BOUMASSATA, A.

    2014-05-01

    Full Text Available In this paper, we propose a wind energy conversion system (WECS at variable speed using a doubly fed induction generator (DFIG controlled on the rotor side through a cycloconverter. The dynamic behavior of the WECS, including the models of the wind turbine, the DFIG, the cycloconverter, and the power control of this system, is investigated. The power control of this system is applied to achieve the independent control of the active and reactive powers exchanged between the wind generator and the grid. In addition, a maximum power point tracking (MPPT control is included in the control system to capture the maximum power from the wind. Moreover, the cycloconverter with DFIG are used to test the possibility to operate in two quadrant modes (sub-synchronous and super-synchronous modes. The description of the proposed system is presented with the detailed dynamic modeling equations. The simulation results are presented, to demonstrate the performance and the efficiency of this system.

  4. Coordinated Control of Superconducting Fault Current Limiter and Superconducting Magnetic Energy Storage for Transient Performance Enhancement of Grid-Connected Photovoltaic Generation System

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2017-01-01

    Full Text Available In regard to the rapid development of renewable energy sources, more and more photovoltaic (PV generation systems have been connected to main power networks, and it is critical to enhance their transient performance under short-circuit faults conditions. This paper proposes and studies the coordinated control of a flux-coupling-type superconducting fault current limiter (SFCL and a superconducting magnetic energy storage (SMES, to improve the fault ride through (FRT capability and smooth the power fluctuation of a grid-connected PV generation system. Theoretical analyses of the device structure, operating principle and control strategy are conducted, and a detailed simulation model of 100 kW class PV generation system is built in MATLAB/SIMULINK. During the simulations of the symmetrical and asymmetrical faults, the maximum power point tracking (MPPT control is disabled, and four different cases including without auxiliary, with SFCL, with SMES, and with SFCL-SMES, are compared. From the demonstrated results, the combination of without MPPT and with SFCL-SMES can more efficiently improve the point of common coupling (PCC voltage sag, inhibit the DC-link overvoltage and alleviate the power fluctuation. Finally, a preliminary parameter optimization method is suggested for the SFCL and the SMES, and it is helpful to promote their future application in the real PV projects.

  5. Microbial leakage of Cavit, IRM, and Temp Bond in post-prepared root canals using two methods of gutta-percha removal: an in vitro study.

    Science.gov (United States)

    Balto, Hanan; Al-Nazhan, Saad; Al-Mansour, Khulood; Al-Otaibi, Moneera; Siddiqu, Yunus

    2005-08-15

    The aim of this study was to evaluate the integrity of the coronal seal of Temp-Bond and compare it to Cavit and IRM after post space preparation using S. faecalis as a microbial tracer. In addition, the affect of two methods of gutta percha removal on the apical seal of root canal fillings was also evaluated. Forty extracted human single rooted teeth were prepared chemomechanically and obturated with gutta percha and AH26 sealer cement using the lateral cold condensation technique to a standardized working length of 15 mm. About 10 mm of the coronal gutta-percha was removed with either Peeso-reamer or a hot plugger. The roots were divided into three experimental groups of 10 roots and a control group. Each experimental group was subdivided equally into two groups of 15 each according to the method of post space preparation. Cavit, IRM, and Temp-Bond were used to seal the access opening. Each root was fixed in a cuvette containing Tryptic Soya Broth which, covered 2 mm of the root apex. Bacterial suspension was introduced through pipette. Fresh bacterial suspension was added every week, and the system was monitored daily for the growth of microorganisms for a period of one month. The results showed there was no significant difference in terms of coronal leakage between the three coronal materials used (P=0.478), but the methods of gutta-percha removal did have an impact on the apical leakage (P=0.047). The mean value showed the Peeso-reamer provided less leakage compared to using a hot plugger during the 30-day experimental time period. It was concluded the temporary type of coronal seal of endodontically treated teeth will not prevent coronal leakage if left for a long period of time. In addition, permanent cementation of the post with the coronal restoration should be carried out as soon as possible to prevent recontamination of the root canal.

  6. Comparing two methods of education (virtual versus traditional) on learning of Iranian dental students: a post-test only design study.

    Science.gov (United States)

    Moazami, Fariborz; Bahrampour, Ehsan; Azar, Mohammad Reza; Jahedi, Farzad; Moattari, Marzieh

    2014-03-05

    The importance of using technologies such as e-learning in different disciplines is discussed in the literature. Researchers have measured the effectiveness of e-learning in a number of fields.Considering the lack of research on the effectiveness of online learning in dental education particularly in Iran, the advantages of these learning methods and the positive university atmosphere regarding the use of online learning. This study, therefore, aims to compare the effects of two methods of teaching (virtual versus traditional) on student learning. This post-test only design study approached 40, fifth year dental students of Shiraz University of Medical Sciences. From this group, 35 students agreed to participate. These students were randomly allocated into two groups, experimental (virtual learning) and comparison (traditional learning). To ensure similarity between groups, we compared GPAs of all participants by the Mann-Whitney U test (P > 0.05). The experimental group received a virtual learning environment courseware package specifically designed for this study, whereas the control group received the same module structured in a traditional lecture form. The virtual learning environment consisted of online and offline materials. Two identical valid, reliable post-tests that consisted of 40 multiple choice questions (MCQs) and 4 essay questions were administered immediately (15 min) after the last session and two months later to assess for knowledge retention. Data were analyzed by SPSS version 20. A comparison of the mean knowledge score of both groups showed that virtual learning was more effective than traditional learning (effect size = 0.69). The newly designed virtual learning package is feasible and will result in more effective learning in comparison with lecture-based training. However further studies are needed to generalize the findings of this study.

  7. Comparison of two methods for measuring γ-H2AX nuclear fluorescence as a marker of DNA damage in cultured human cells: applications for microbeam radiation therapy

    Science.gov (United States)

    Anderson, D.; Andrais, B.; Mirzayans, R.; Siegbahn, E. A.; Fallone, B. G.; Warkentin, B.

    2013-06-01

    Microbeam radiation therapy (MRT) delivers single fractions of very high doses of synchrotron x-rays using arrays of microbeams. In animal experiments, MRT has achieved higher tumour control and less normal tissue toxicity compared to single-fraction broad beam irradiations of much lower dose. The mechanism behind the normal tissue sparing of MRT has yet to be fully explained. An accurate method for evaluating DNA damage, such as the γ-H2AX immunofluorescence assay, will be important for understanding the role of cellular communication in the radiobiological response of normal and cancerous cell types to MRT. We compare two methods of quantifying γ-H2AX nuclear fluorescence for uniformly irradiated cell cultures: manual counting of γ-H2AX foci by eye, and an automated, MATLAB-based fluorescence intensity measurement. We also demonstrate the automated analysis of cell cultures irradiated with an array of microbeams. In addition to offering a relatively high dynamic range of γ-H2AX signal versus irradiation dose ( > 10 Gy), our automated method provides speed, robustness, and objectivity when examining a series of images. Our in-house analysis facilitates the automated extraction of the spatial distribution of the γ-H2AX intensity with respect to the microbeam array — for example, the intensities in the peak (high dose area) and valley (area between two microbeams) regions. The automated analysis is particularly beneficial when processing a large number of samples, as is needed to systematically study the relationship between the numerous dosimetric and geometric parameters involved with MRT (e.g., microbeam width, microbeam spacing, microbeam array dimensions, peak dose, valley dose, and geometric arrangement of multiple arrays) and the resulting DNA damage.

  8. Controlling

    OpenAIRE

    Hriňáková, Daniela

    2014-01-01

    The topic of my diploma thesis is controlling. The first part is theoretical where I describe the history, meaning and functions of controlling. After that I also specify the methods of strategical, operational and cost controlling. The practical part applied method of controlling to the selected company. The aim of this study is to determine the benefits of controlling for the company. At the operational level it describes the process of controlling in the firm and there are given suggestion...

  9. Estimating Apparent Nutrient Digestibility of Diets Containing Leucaena leucocephala or Moringa oleifera Leaf Meals for Growing Rabbits by Two Methods

    Science.gov (United States)

    Safwat, A. M.; Sarmiento-Franco, L.; Santos-Ricalde, R. H.; Nieves, D.; Sandoval-Castro, C. A.

    2015-01-01

    This study aimed to evaluate the nutrient digestibility of growing rabbits fed diets with different levels of either Leucaena leucocephala (LLM) or Moringa oleifera (MOLM) leaf meals and also to compare total collection and TiO2 marker methods for estimating digestibility. A total of 30 California growing rabbits (1.81±0.19 kg live weight on average) were randomly distributed into five experimental groups of six rabbits each and were housed in individual cages. The groups were control, 30% LLM, 40% LLM, 30% MOLM, and 40% MOLM. All groups received pelleted diets for two weeks; diets also contained 4 g/kg titanium dioxide as dietary marker. Daily feed intake was recorded during the whole experimental period and total feces were collected daily and weighed individually during four days. The results showed that there were no difference (p>0.05) in feed, dry matter (DM), organic matter (OM), crude protein (CP), digestible energy, and crude fiber (CF) intake between the control group and the other experimental groups. The apparent digestibility values of DM, OM, CP, CF, acid detergent fiber, and gross energy were the highest for control group (p = 0.001), meanwhile MOLM diets had generally higher nutrient digestibility coefficients than LLM diets. Increasing the inclusion level of leaf meal in the diet from 30% to 40% improved the digestibility of CF from 45.02% to 51.69% for LLM and from 48.11% to 55.89% for MOLM. Similar results for apparent nutrient digestibility coefficients were obtained when either total collection or indigestible marker method was used. In conclusion, the digestibility of MOLM containing diets were better than LLM diets, furthermore TiO2 as an external marker could be used as a simple, practical and reliable method to estimate nutrients digestibility in rabbit diets. PMID:26104524

  10. A comparison of two methods of teaching. Computer managed instruction and keypad questions versus traditional classroom lecture.

    Science.gov (United States)

    Halloran, L

    1995-01-01

    Computers increasingly are being integrated into nursing education. One method of integration is through computer managed instruction (CMI). Recently, technology has become available that allows the integration of keypad questions into CMI. This brings a new type of interactivity between students and teachers into the classroom. The purpose of this study was to evaluate differences in achievement between a control group taught by traditional classroom lecture (TCL) and an experimental group taught using CMI and keypad questions. Both control and experimental groups consisted of convenience samples of junior nursing students in a baccalaureate program taking a medical/surgical nursing course. Achievement was measured by three instructor-developed multiple choice examinations. Findings demonstrated that although the experimental group demonstrated increasingly higher test scores as the semester progressed, no statistical difference was found in achievement between the two groups. One reason for this may be phenomenon of vampire video. Initially, the method of presentation overshadowed the content. As students became desensitized to the method, they were able to focus and absorb more content. This study suggests that CMI and keypads are a viable teaching option for nursing education. It is equal to TCL in student achievement and provides a new level of interaction in the classroom setting.

  11. Adaptive Backstepping Control Based on Floating Offshore High Temperature Superconductor Generator for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Feng Yang

    2014-01-01

    Full Text Available With the rapid development of offshore wind power, the doubly fed induction generator and permanent magnet synchronous generator cannot meet the increasing request of power capacity. Therefore, superconducting generator should be used instead of the traditional motor, which can improve generator efficiency, reduce the weight of wind turbines, and increase system reliability. This paper mainly focuses on nonlinear control in the offshore wind power system which is consisted of a wind turbine and a high temperature superconductor generator. The proposed control approach is based on the adaptive backstepping method. Its main purpose is to regulate the rotor speed and generator voltage, therefore, achieving the maximum power point tracking (MPPT, improving the efficiency of a wind turbine, and then enhancing the system’s stability and robustness under large disturbances. The control approach can ensure high precision of generator speed tracking, which is confirmed in both the theoretical analysis and numerical simulation.

  12. Control strategy for a distributed DC power system with renewable energy

    Energy Technology Data Exchange (ETDEWEB)

    Kurohane, Kyohei; Uehara, Akie; Senjyu, Tomonobu; Yona, Atsushi; Urasaki, Naomitsu [University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami, Okinawa 903-0213 (Japan); Funabashi, Toshihisa [Meidensha Corporation, 36-2 Nihonbashi-Hakozakicho, Chuo-ku, Tokyo 103-8513 (Japan); Kim, Chul-Hwan [Sungkyunkwan University and NPT Center, Suwon City 440-746 (Korea)

    2011-01-15

    This paper deals with a DC-micro-grid with renewable energy. The proposed method is composed of a gearless wind power generation system, a battery, and DC loads in a DC distribution system. The battery helps to avoid the DC over-voltages by absorbing the power of the permanent magnet synchronous generator (PMSG) during line-fault. In addition, the control schemes presented in this paper including the maximum power point tracking (MPPT) control and a pitch angle control for the gearless wind turbine generator. By means of the proposed method, high-reliable power can be supplied to the DC distribution system during the line-fault and stable power supply from the PMSG can be achieved after line-fault clearing. The effectiveness of the proposed method is examined in a MATLAB/Simulink {sup registered} environment. (author)

  13. Optimal tracking and second order sliding power control of the DFIG wind turbine

    Science.gov (United States)

    Abdeddaim, S.; Betka, A.; Charrouf, O.

    2017-02-01

    In the present paper, an optimal operation of a grid-connected variable speed wind turbine equipped with a Doubly Fed Induction Generator (DFIG) is presented. The proposed cascaded nonlinear controller is designed to perform two main objectives. In the outer loop, a maximum power point tracking (MPPT) algorithm based on fuzzy logic theory is designed to permanently extract the optimal aerodynamic energy, whereas in the inner loop, a second order sliding mode control (2-SM) is applied to achieve smooth regulation of both stator active and reactive powers quantities. The obtained simulation results show a permanent track of the MPP point regardless of the turbine power-speed slope moreover the proposed sliding mode control strategy presents attractive features such as chattering-free, compared to the conventional first order sliding technique (1-SM).

  14. A comparison of two methods for the evaluation of the daily urinary fluoride excretion in Romanian pre-school children.

    Science.gov (United States)

    Székely, M; Bánóczy, J; Fazakas, Z; Hobai, S; Villa, A

    2008-03-01

    To compare two different methods of estimating daily fluoride urinary excretion in pre-school children under stable fluoride intake conditions. Thirty-five healthy kindergarten children, permanent residents of Targu-Mures, Romania, where the average drinking water fluoride concentration is 0.12 mg F/L, participated on two separate occasions, when they were aged 4-6 and 5-7 years, respectively in the collection of a) a mid-morning spot urine sample and b) a 16-h time-controlled urine sampling. In case a), the ratio of concentrations of fluoride and creatinine were measured, while in case b) the rates of fluoride excretion in two separate 8-hour periods were used to estimate the 24-hour fluoride urinary excretion. The estimated average daily fluoride urinary excretion values (S.D.) were 0.318 (0.182) mg F/day for method a) and 0.341 (0.193) mg F/day for method b). These values were not significantly different (Mann-Whitney U test; p = 0.49). The estimated daily fluoride doses were 0.040 (0.021) and 0.043 (0.022) mg F/kg body weight/day, respectively. The latter values were not significantly different (Mann Whitney U test; p = 0.38). Results obtained suggest that under stable F-intake conditions the estimation of the daily fluoride urinary excretion by means of a mid-morning spot urine sample yields comparable results to those obtained with the more involved method of separate, two 8 h (16 h) time-controlled urine sampling recommended by the WHO. Use of spot urine sampling appears to be particularly useful for epidemiological studies.

  15. Starting and stopping control on power conditioner in photovoltaic power system; Taiyoko hatsuden system ni okeru power conditioner no kido teishi seigyo ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, M.; Ishihara, Y.; Todaka, T.; Harada, K. [Doshisha University, Kyoto (Japan); Oshiro, H.; Nakamura, H. [Japan Quality Assurance Organization, Tokyo (Japan)

    1997-11-25

    Studies are made about the control of the power conditioner over the maximum power point tracking (MPPT) function in a photovoltaic power generation system. The analysis is conducted by means of computer simulation into the effect of a start/stop function added to the control of MPPT and the effect on the generation of power of the setting of parameters in the start/stop function. The reduction in output power due to difference between the actual operation point and the optimum operation point is evaluated by use of a load matching correction factor. In this simulation, it is assumed that the solar cell array consists of 13 rows in 5 parallel columns, is capable of a normal output of 3.149kW, has a panel tilted at 30 degrees, and faces due south. The power conditioner is assumed to be a system rated at 3kVA, equipped with system interconnection and back flow features. As a result, it is learned that the stop voltage should be set at 180V or lower and the steady voltage near 185.5V for a good result and that there is not much need after all for the start/stop technique. 2 refs., 8 figs., 2 tabs.

  16. Comparison of Two Methods for Inducing Reflex Cough in Patients With Parkinson's Disease, With and Without Dysphagia.

    Science.gov (United States)

    Hegland, Karen W; Troche, Michelle S; Brandimore, Alexandra; Okun, Michael S; Davenport, Paul W

    2016-02-01

    Aspiration pneumonia is a common cause of death in people with Parkinson's disease (PD). Dysfunctional swallowing occurs in the majority of people with PD, and research has shown that cough function is also impaired. Previous studies suggest that testing reflex cough by having participants inhale a cough-inducing stimulus through a nebulizer may be a reliable indicator of swallowing dysfunction, or dysphagia. The primary goal of this study was to determine the cough response to two different cough-inducing stimuli in people with and without PD. The second goal of this study was to compare the cough response to the two different stimuli in people with PD, with and without swallowing dysfunction. Seventy adults (49 healthy and 21 with PD) participated in the study. Aerosolized water (fog) and 200 μM capsaicin were used to induce cough. Each substance was placed in a small, hand-held nebulizer, and presented to the participant. Each cough stimulus was presented three times. The total number of coughs produced to each stimulus trial was recorded. All participants coughed more to capsaicin versus fog (p dysphagia. The data show a differential response of the PD participants to the capsaicin versus fog stimuli. Clinically, this finding may allow for earlier identification of people with PD who are in need of a swallowing evaluation. As well, there are implications for the neural control of cough in this patient population.

  17. Bacteria-foraging based-control of high-performance railway level-crossing safety drives fed from photovoltaic array

    Directory of Open Access Journals (Sweden)

    Essamudin A. Ebrahim

    2016-12-01

    Full Text Available In the past ten years, railway level-crossing accidents have noticeably escalated in an indisputably preposterous manner, this devastating snag opened the floodgates for the frustrating death of a numerous number of the third world’s citizens, especially in Egypt. To tackle with this problem, a fully intelligent control system is required, which must be automated without human intervention. So, in this research, a new proposed level-crossing tracking system is designed and introduced. The system comprises a high-performance induction motor (IM fed from photovoltaic (PV array, the boom barrier (gate with its mechanism – as a load – buck–boost converter, inverter, and two smart PI-controllers. The first one is designed to regulate the duty cycle of the converter to its optimum value required to balance between maximum power point tracking (MPPT and keeping dc-link voltage of the inverter at a minimum level needed to maintain the motor internal torque at rated value. The second PI-controller is designed for speed control of indirect field-oriented vector-control (IFO-VC IM. The proposed design problems of MPPT, dc-link voltage and speed controllers are solved as optimization problems by bacteria-foraging optimization (BFO algorithm to search for the optimal PI-parameters. The simulation test results are acquired when using the battery-less PV-array with and without the proposed controllers. Also, results are obtained when applying several prescribed speed trajectories to test the robustness against PV-irradiance fluctuations and motor-dynamic disturbances. From these results, the proposed intelligent controllers are robust compared to classical Ziegler–Nichols (ZN PI-controllers and also when the motor is directly fed from PV generator without converter.

  18. An Improvement of a Fuzzy Logic-Controlled Maximum Power Point Tracking Algorithm for Photovoltic Applications

    Directory of Open Access Journals (Sweden)

    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.

  19. Grid-connected Photovoltaic Micro-inverter with New Hybrid Control LLC Resonant Converter

    DEFF Research Database (Denmark)

    Xingkui, Mao; Qisheng, Huang; Qingbo, Ke

    2016-01-01

    A high-efficiency photovoltaic (PV) micro-inverter consisting of two power stages i.e. a LLC resonant converter with a new hybrid control scheme and a dc-ac inverter is proposed, studied and designed in this paper. In the first power stage, the new hybrid control combining pulse......-frequency modulation (PFM) and phase-shift pulse-width modulation (PS-PWM) is employed on a full-bridge LLC dc-dc converter, in order to achieve high efficiency when PV output voltage varies in a wide range. Moreover, a maximum power point tracking (MPPT) method based on power perturbation is implemented in the dc-ac...... inverter. Therefore, the complexity of regulating LLC converter can be reduced effectively, and efficiency optimal design can be carried out through the proposed designing procedure for the resonant tank of LLC converter. Finally, a prototype of the proposed PV micro-inverter (PVMI) is developed with rated...

  20. Adaptive robust maximum power point tracking control for perturbed photovoltaic systems with output voltage estimation.

    Science.gov (United States)

    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. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  1. Dynamic Sliding Mode Evolution PWM Controller for a Novel High-Gain Interleaved DC-DC Converter in PV System

    Directory of Open Access Journals (Sweden)

    Taizhou Bei

    2014-01-01

    Full Text Available Considering the disadvantages of the traditional high-gain DC-DC converter such as big size, high voltage stress of switches, and large input current ripple, a novel high-gain interleaved boost converter with coupled-inductor and switched-capacitor was proposed correspondingly and the operation principle together with the steady-state analysis of this converter was also described. Besides, a new control approach-dynamic sliding mode evolution PWM controller (DSME PWM for the novel topological converter based on both dynamic evolution and sliding mode control was also presented. From the simulation results and experimental validation the proposed converter can fulfill high-gain boost, low ripple of both the input current and the output voltage. Furthermore, MPPT technique can be also achieved in a short time by simulation. The efficiency and stability of the converter proposed in this paper can be improved.

  2. The aptitude of the soils for the production of sugarcane. Part 2: Comparison of two methods at ‘Ciudad Caracas’ sugarcane mill

    Directory of Open Access Journals (Sweden)

    Nelson C. Arzola Pina

    2015-03-01

    Full Text Available The object of this study was to compare two methods for determining the aptitude of soils for growing Sugarcane in Cuba. The information was provided by three sugarcane farms owned by Ciudad Caracas sugarcane mill in the municipality of Santa Isabel de Las Lajas in Cienfuegos. The information of the soils from each farm was taken from the 1:25 000 scale cadastral maps designed by Ministerio de la Agricultura (MINAG. Rainfall data was collected from the nearby stations rain gauges. And the sugarcane yield was reported by each farm. The aptitude of the soils was determined by two methods (AGRO 24 de 1993 y Arzola de 1999 using the information available. Results showed that both methods are appropriate for selecting soils with higher productive potential, and are a useful tool for making right decisions for optimizing the land use at each sugarcane farm.

  3. Adaptive control for solar energy based DC microgrid system development

    Science.gov (United States)

    Zhang, Qinhao

    During the upgrading of current electric power grid, it is expected to develop smarter, more robust and more reliable power systems integrated with distributed generations. To realize these objectives, traditional control techniques are no longer effective in either stabilizing systems or delivering optimal and robust performances. Therefore, development of advanced control methods has received increasing attention in power engineering. This work addresses two specific problems in the control of solar panel based microgrid systems. First, a new control scheme is proposed for the microgrid systems to achieve optimal energy conversion ratio in the solar panels. The control system can optimize the efficiency of the maximum power point tracking (MPPT) algorithm by implementing two layers of adaptive control. Such a hierarchical control architecture has greatly improved the system performance, which is validated through both mathematical analysis and computer simulation. Second, in the development of the microgrid transmission system, the issues related to the tele-communication delay and constant power load (CPL)'s negative incremental impedance are investigated. A reference model based method is proposed for pole and zero placements that address the challenges of the time delay and CPL in closed-loop control. The effectiveness of the proposed modeling and control design methods are demonstrated in a simulation testbed. Practical aspects of the proposed methods for general microgrid systems are also discussed.

  4. Modeling and Controller Design of PV Micro Inverter without Using Electrolytic Capacitors and Input Current Sensors

    Directory of Open Access Journals (Sweden)

    Faa Jeng Lin

    2016-11-01

    Full Text Available This paper outlines the modeling and controller design of a novel two-stage photovoltaic (PV micro inverter (MI that eliminates the need for an electrolytic capacitor (E-cap and input current sensor. The proposed MI uses an active-clamped current-fed push-pull DC-DC converter, cascaded with a full-bridge inverter. Three strategies are proposed to cope with the inherent limitations of a two-stage PV MI: (i high-speed DC bus voltage regulation using an integrator to deal with the 2nd harmonic voltage ripples found in single-phase systems; (ii inclusion of a small film capacitor in the DC bus to achieve ripple-free PV voltage; (iii improved incremental conductance (INC maximum power point tracking (MPPT without the need for current sensing by the PV module. Simulation and experimental results demonstrate the efficacy of the proposed system.

  5. Compatibility of Anfis controller and FPGA in solar power generation for a domestic oad

    Directory of Open Access Journals (Sweden)

    Arulprakash Andigounder

    2016-06-01

    Full Text Available Among other soft computing techniques, the Adaptive Neuro Fuzzy Inference System (Anfis gives a significant and advantageous result in solar power generation, especially in tracking the maximum power point. Due to the dynamic nature of solar irradiance and temperature, efficient energy conversion is not possible. However, advancements in the areas of artificial intelligence have made it possible to overcome the hurdles. The Maximum Power Point Tracking (MPPT technique adopting the advantages of Anfis has been proven to be more successful with a fast dynamic response and high accuracy. The complete system is modeled using Matlab/Simulink; the hardware results are validated with the benefits of Field Programmable Logic Array (FPGA instead of ordinary micro-controllers.

  6. Home-based leg-strengthening exercise improves function 1 year after hip fracture: a randomized controlled study.

    Science.gov (United States)

    Mangione, Kathleen K; Craik, Rebecca L; Palombaro, Kerstin M; Tomlinson, Susan S; Hofmann, Mary T

    2010-10-01

    To compare the effectiveness of a short-term leg-strengthening exercise program with that of attentional control on improving strength, walking abilities, and function 1 year after hip fracture. Randomized controlled pilot study. Patients' homes. Community-dwelling older adults (n=26) 6 months after hip fracture at baseline. Exercise and control participants received interventions from physical therapists twice a week for 10 weeks. The exercise group received high-intensity leg-strengthening exercises. The control group received transcutaneous electrical nerve stimulation and mental imagery. Isometric force production of lower extremity muscles, usual and fast gait speed, 6-minute walk (6-MW) distance, modified Physical Performance Test (mPPT), and Medical Outcomes Study 36-item Short Form Survey (SF-36) physical function. The primary endpoint was 1 year after fracture. Isometric force production (P=.006), usual (P=.02) and fast (P=.03) gait speed, 6-MW distance (P=.005), and mPPT score (PmPPT score, 0.56 for gait speed, 0.49 for 6-MW, and 0.30 for SF-36 score. More patients in the exercise group made meaningful changes in gait speed and 6-MW distance than control patients (chi-square P=.004). A 10-week home-based progressive resistance exercise program was sufficient to achieve moderate to large effects on physical performance and quality of life and may offer an alternative intervention mode for patients with hip fracture who are unable to leave home by 6 months after the fracture. The effects were maintained at 3 months after completion of the training program. © 2010, Copyright the Authors. Journal compilation © 2010, The American Geriatrics Society.

  7. Implementation of FPGA-Based Charge Control for a Self-Sufficient Solar Tracking Power Supply System

    Directory of Open Access Journals (Sweden)

    Jui-Ho Chen

    2016-02-01

    Full Text Available This study used a field-programmable gate array (FPGA with a Xilinx Spartan-3 FPGA to implement Reflex charge control in a dual-axis solar tracking system with maximum power point tracking (MPPT. The chaos embedded particle swarm optimization method was used to search for the optimum gain constants of the PI controller and the Reflex charging frequency. This scheme not only increases the output power of solar panels but also has a significant effect on switching loss and oscillation of solar charging. The experiment results showed that the proposed method can also significantly improve temperature rise, and that charging efficiency is also better than it is in a traditional charge mode. The results also showed that charging power was enough for solar tracking and the requirements of the charging system. The most significant contribution of this paper is that the scheme can be applied to any active solar tracking and charging system.

  8. Second-Order Harmonic Reduction Technique for Photovoltaic Power Conditioning Systems Using a Proportional-Resonant Controller

    Directory of Open Access Journals (Sweden)

    Hae-Gwang Jeong

    2013-01-01

    Full Text Available This paper proposes a second-order harmonic reduction technique using a proportional-resonant (PR controller for a photovoltaic (PV power conditioning system (PCS. In a grid-connected single-phase system, inverters create a second-order harmonic at twice the fundamental frequency. A ripple component unsettles the operating points of the PV array and deteriorates the operation of the maximum power point tracking (MPPT technique. The second-order harmonic component in PV PCS is analyzed using an equivalent circuit of the DC/DC converter and the DC/AC inverter. A new feed-forward compensation technique using a PR controller for ripple reduction is proposed. The proposed algorithm is advantageous in that additional devices are not required and complex calculations are unnecessary. Therefore, this method is cost-effective and simple to implement. The proposed feed-forward compensation technique is verified by simulation and experimental results.

  9. Adaptive Controller for Drive System PMSG in Wind Turbine

    Directory of Open Access Journals (Sweden)

    Gnanambal

    2014-07-01

    Full Text Available This paper proposes adaptive Maximum Power Point Tracking (MPPT controller for Permanent Magnet Synchronous Generator (PMSG wind turbine and direct power control for grid side inverter for transformer less integration of wind energy. PMSG wind turbine with two back to back voltage source converters are considered more efficient, used to make real and reactive power control. The optimal control strategy has introduced for integrated control of PMSG Maximum Power Extraction, DC link voltage control and grid voltage support controls. Simulation model using MATLAB Simulink has developed to investigate the performance of proposed control techniques for PMSG wind turbine steady and variable wind conditions. This paper shows that the direct driven grid connected PMSG system has excellent performances and confirms the feasibility of the proposed techniques. While the wind turbine market continues to be dominated by conventional gear-driven wind turbine systems, the direct drive is attracting attention. PM machines are more attractive and superior with higher efficiency and energy yield, higher reliability, and power-to-weight ratio compared with electricity-excited machines.

  10. Modelling of a PMSG Wind Turbine with Autonomous Control

    Directory of Open Access Journals (Sweden)

    Chia-Nan Wang

    2014-01-01

    Full Text Available The aim of this research is to model an autonomous control wind turbine driven permanent magnetic synchronous generator (PMSG which feeds alternating current (AC power to the utility grid. Furthermore, this research also demonstrates the effects and the efficiency of PMSG wind turbine which is integrated by autonomous controllers. In order for well autonomous control, two voltage source inverters are used to control wind turbine connecting with the grid. The generator-side inverter is used to adjust the synchronous generator as well as separating the generator from the grid when necessary. The grid-side inverter controls the power flow between the direct current (DC bus and the AC side. Both of them are oriented control by space vector pulse width modulation (PWM with back-to-back frequency inverter. Moreover, the proportional-integral (PI controller is enhanced to control both of the inverters and the pitch angle of the wind turbine. Maximum power point tracking (MPPT is integrated in generator-side inverter to track the maximum power, when wind speed changes. The simulation results in Matlab Simulink 2012b showing the model have good dynamic and static performance. The maximum power can be tracked and the generator wind turbine can be operated with high efficiency.

  11. Control scheme towards enhancing power quality and operational efficiency of single-phase two-stage grid-connected photovoltaic systems

    Directory of Open Access Journals (Sweden)

    Mahmoud Salem

    2015-12-01

    Full Text Available Achieving high reliable grid-connected photovoltaic (PV systems with high power quality and high operation efficiency is highly required for distributed generation units. A double grid-frequency voltage ripple is found on the dc-link voltage in single-phase photovoltaic grid-connected systems due to the unbalance of the instantaneous dc input and ac output powers. This voltage ripple has undesirable effects on the power quality and operational efficiency of the whole system. Harmonic distortion in the injected current to the grid is one of the problems caused by this double grid-frequency voltage ripple. The double grid frequency ripple propagates to the PV voltage and current which disturb the extracted maximum power from the PV array. This paper introduces intelligent solutions towards mitigate the side effects of the double grid-frequency voltage ripple on the transferred power quality and the operational efficiency of single-phase two-stage grid-connected PV system. The proposed system has three control loops: MPPT control loop, dc-link voltage control loop and inverter current control loop. Solutions are introduced for all the three control loops in the system. The current controller cancels the dc-link voltage effect on the total harmonic distortion of the output current. The dc-link voltage controller is designed to generate a ripple free reference current signal that leads to enhance the quality of the output power. Also a modified MPPT controller is proposed to optimize the extracted power from the PV array. Simulation results show that higher injected power quality is achieved and higher efficiency of the overall system is realized.

  12. Evaluation of two methods to measure hemoglobin concentration among women with genetic hemoglobin disorders in Cambodia: a method-comparison study.

    Science.gov (United States)

    Karakochuk, Crystal D; Janmohamed, Amynah; Whitfield, Kyly C; Barr, Susan I; Vercauteren, Suzanne M; Kroeun, Hou; Talukder, Aminuzzaman; McLean, Judy; Green, Timothy J

    2015-02-20

    Genetic hemoglobin (Hb) E variants are common in Cambodia and result in an altered and unstable Hb molecule. We evaluated two methods to measure Hb concentration among individuals with and without Hb variants using a hemoglobinometer (HemoCue) and a hematology analyzer (Sysmex XT-1800i). We determined the bias and concordance between the methods among 420 Cambodian women (18-45 y). Bias and concordance appeared similar between methods among women with no Hb disorders (n=195, bias=2.5, ρc=0.68), women with Hb E variants (n=133, bias=2.5, ρc=0.78), and women with other Hb variants (n=92, bias=2.7, ρc=0.73). The overall bias was 2.6g/l, resulting in a difference in anemia prevalence of 11.5% (41% using HemoCue and 29.5% using Sysmex, p<0.001). Based on visual interpretation of the concordance plots, the HemoCue device appears to underestimate Hb concentrations at lower Hb concentrations and to overestimate Hb concentrations at higher Hb concentrations (in comparison to the Sysmex analyzer). Bias and concordance were similar across groups, suggesting the two methods of Hb measurement were comparable. We caution field staff, researchers and policy makers in the interpretation of data and the impact that bias between methods can have on anemia prevalence rates. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Semiautomatic three-dimensional CT ventricular volumetry in patients with congenital heart disease: agreement between two methods with different user interaction.

    Science.gov (United States)

    Goo, Hyun Woo; Park, Sang-Hyub

    2015-12-01

    To assess agreement between two semi-automatic, three-dimensional (3D) computed tomography (CT) ventricular volumetry methods with different user interactions in patients with congenital heart disease. In 30 patients with congenital heart disease (median age 8 years, range 5 days-33 years; 20 men), dual-source, multi-section, electrocardiography-synchronized cardiac CT was obtained at the end-systolic (n = 22) and/or end-diastolic (n = 28) phase. Nineteen left ventricle end-systolic (LV ESV), 28 left ventricle end-diastolic (LV EDV), 22 right ventricle end-systolic (RV ESV), and 28 right ventricle end-diastolic volumes (RV EDV) were successfully calculated using two semi-automatic, 3D segmentation methods with different user interactions (high in method 1, low in method 2). The calculated ventricular volumes of the two methods were compared and correlated. A P value congenital heart disease, 3D CT ventricular volumetry shows good agreement and high correlation between the two methods, but method 2 tends to slightly underestimate LV ESV, LV EDV, and RV ESV.

  14. Measurement of center-edge angle in developmental dysplasia of the hip: a comparison of two methods in patients under 20 years of age

    International Nuclear Information System (INIS)

    Oemeroglu, H.; Bicimoglu, A.; Agus, H.; Tuemer, Y.

    2002-01-01

    Objective: To analyse in detail the two methods for the measurement of the center-edge (CE) angle in developmental dysplasia of the hip (DDH) in children and adolescents. Design: Four observers independently interpreted the radiographs of 51 surgically treated and 15 unaffected hips on two occasions. CE angle was measured by using two methods: classic (Wiberg) and refined (Ogata et al.). Intraobserver and interobserver variations of both methods were calculated and the effect of age and treatment type on the two measurement methods were analysed. Results: Following 528 measurements in 66 hips, the mean classic CE angle was 28.2 and the mean refined CE angle, 19.9 . The classic CE angle had nearly 1 less intraobserver and interobserver variation than the refined CE angle. Classic angle measurements were obviously higher than refined ones in the hips of children under 9 years of age and in hips in which an innominate osteotomy had been performed. Conclusion: Although CE angle of Wiberg, which is an important radiographic indicator, has an adequate level of reliability and reproducibility it may not reflect the true lateral femoral head coverage in some cases. (orig.)

  15. Application of the DTC control in the photovoltaic pumping system

    International Nuclear Information System (INIS)

    Moulay-Idriss, Chergui; Mohamed, Bourahla

    2013-01-01

    Highlights: ► To improve the efficiency of PV systems, under different temperature and irradiance conditions. ► The MPPT and different control method for the induction motor were applied. ► The DTC in PV pumping system introduced and performance studied. ► The introductions of DTC in PV systems are very promising. ► Optimizing the water pumping system speed response characteristic by DTC. - Abstract: We aim to find a better control and optimization among the different functions of a solar pumping system. The photovoltaic panel can provide a maximum power only for defined output voltage and current. In addition, the operation to get the maximum power depends on the terminals of load, mostly a non-linear load like induction motor. In this work, we propose an intelligent control method for the maximum power point tracking of a photovoltaic system under variable temperature and irradiance conditions. The system was tested without maximum power point tracking, with the use of Scalar-Based control motor, but we cannot maintain the speed optimal. Next, we developed several methods for the control. Finally, we have chosen the Direct Torque Control.

  16. Grid-Connection Half-Bridge PV Inverter System for Power Flow Controlling and Active Power Filtering

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2012-01-01

    Full Text Available A half-bridge photovoltaic (PV system is proposed, which can not only deal with bidirectional power flowing but also improve power quality. According to varying insolation, the system conditions real power for dc and ac loads to accommodate different amounts of PV power. Furthermore, the system eliminates current harmonics and improves power factor simultaneously. As compared with conventional PV inverter, the total number of active switches and current sensors can be reduced so that its cost is lower significantly. For current command determination, a linear-approximation method (LAM is applied to avoid the complicated calculation and achieve the maximum power point tracking (MPPT feature. For current controlling, a direct-source-current-shaping (DSCS algorithm is presented to shape the waveform of line current. Simulation results and practical measurements also demonstrate the feasibility of the proposed half-bridge PV system.

  17. A Rotating Speed Controller Design Method for Power Levelling by Means of Inertia Energy in Wind Power Systems

    DEFF Research Database (Denmark)

    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...... in the frequency domain for power leveling. Moreover, the impact of other parameters on power leveling, including the time constant of maximum power point tracking (MPPT) and the rotor inertia, are also studied. With the proposed optimal design, the power fluctuations are mitigated as much as possible, while...

  18. Study of ciclosporine blood levels in patients after kidney or bone-marrow transplantation. Comparison between the two methods, fluorescence polarization immunoassay and radioimmunoassay

    International Nuclear Information System (INIS)

    Sadeg, N.; Pham Huy, C.; Claude, J.R.; Postaire, M.; Lebrec, H.; Hamon, M.; Broyer, M.; Gagnadoux, M.F.; Fischer, A.

    1989-01-01

    The apparition of ciclosporine, immunodepressive drug, has largely improved the organ transplantations. However, the range of blood concentrations must be defined to allow the efficacity of ciclosporine therapy and to avoid toxic reactions, because there are very important variations for a same dosage according to the individuals and the diseases. Relative to the low concentrations to be determined (about one hundred ng/ml), the most useful methods for ciclosporine measurement are based on immunochemical assays. This work compares the two methods: radioimmunoassay (RIA) and fluorescence polarization immunoassay (FPIA) simultaneously performed on several hundred samples. A very significant correlation exists between the two techniques (r = 0.80). The advantages of immunofluorescent assay consists in rapidity, sensibility and facility to realize emergency analysis [fr

  19. Comparison of two methods of preparation of tissue to study the internal anatomy of the delphacid Togosodes orizicolus with microscopy of electronic light

    International Nuclear Information System (INIS)

    Macaya-Lizano, A.V.; Pereira, R.; Espinoza, A.M.

    1997-01-01

    Two methods of embedding, sectioning and staining were developed to study the internal anatomy of delphacid plant hopper Tagosodes orizicolus, one of the most important plagues of rice in Latin America and the only vector of the white leaf tenuivirus (RHBV), using both light and electron microscopy. The paraffines-hematoxyline-eosin Y method allows color identification of tissues, for example purple for fat tissue, pink for muscles, yellow-brown for exocutile, while the resin-toluidine-blue method preserves better the ultrastructure but do not permit color identification. The information obtained by these procedures is complementary and the material can also be used for in situ studies by immuno microscopy, to assess the changes in cell ultrastructure and the localization and replication of the RHBV during its infection cycle in the insect vector. (author) [es

  20. Comparison of microleakage of Scotchbond™ Universal Adhesive with methacrylate resin in Class V restorations by two methods: Swept source optical coherence tomography and dye penetration.

    Science.gov (United States)

    Kermanshah, Hamid; Khorsandian, Hossein

    2017-01-01

    One of the most important factors in restoration failure is microleakage at the restoration interface. Furthermore, a new generation of bonding, Scotchbond Universal (multi-mode adhesive), has been introduced to facilitate the bonding steps. The aim of this study was to compare the microleakage of Class V cavities restored using Scotchbond™ Universal with Scotchbond Multi-Purpose in two procedures. Eighteen freshly extracted human molars were used in this study. Thirty-six standardized Class V cavities were prepared on the buccal and lingual surfaces. The teeth were divided into three groups: (1) Group A: Scotchbond Universal with "self-etching" procedure and nanohybrid composite Filtek Z350. (2) Group B: Scotchbond Universal with "total etching" procedure and Filtek Z350. (3) Group C: Scotchbond Multi-Purpose and Filtek Z350. Microleakage at enamel and dentinal margins was evaluated after thermocycling under 5000 cycles by two methods of microleakage assay: swept source optical coherence tomography (OCT) and dye penetration. Wilcoxon's signed-rank test and Kruskal-Wallis test were used to analyze microleakage. In silver nitrate dye penetration method, group A exhibited the minimum microleakage at dentin margins and group C exhibited the minimum microleakage at enamel margins ( P < 0.05). Furthermore, in OCT method, group C demonstrated the minimum microleakage at enamel margins ( P = 0.047), with no difference in the microleakage rate at dentin margins. Scotchbond Universal with "self-etching" procedure at dentin margin exhibited more acceptable performance compared to the Scotchbond Multi-Purpose with the two methods.

  1. Advanced control of direct-driven PMSG generator in wind turbine system

    Directory of Open Access Journals (Sweden)

    Gajewski Piotr

    2016-12-01

    Full Text Available The paper presents the advanced control system of the wind energy conversion with a variable speed wind turbine. The considered system consists of a wind turbine with the permanent magnet synchronous generator (PMSG, machine side converter (MSC, grid side converter (GSC and control circuits. The mathematical models of a wind turbine system, the PMSG generator and converters have been described. The control algorithms of the converter systems based on the methods of vector control have been applied. In the advanced control system of the machine side converter the optimal MPPT control method has been used. Additionally the pitch control scheme is included in order to achieve the limitation of maximum power and to prevent mechanical damage of the wind turbine. In the control system of the grid side converter the control of active and reactive power has been applied with the application of Voltage Oriented Control (VOC. The performance of the considered wind energy system has been studied by digital simulation. The results of simulation studies confirmed the good effectiveness of the considered wind turbine system and very good performance of the proposed methods of vector control and control systems.

  2. A control strategy for PV stand-alone applications

    Science.gov (United States)

    Slouma, S.; Baccar, H.

    2015-04-01

    This paper proposes a stand-alone photovoltaic (PV) system study in domestic applications. Because of the decrease in power of photovoltaic module as a consequence of changes in solar radiation and temperature which affect the photovoltaic module performance, the design and control of DC-DC buck converter was proposed for providing power to the load from a photovoltaic source.In fact, the control of this converter is carried out with integrated MPPT (Maximum Power Point Tracking) algorithm which ensures a maximum energy generated by the PV arrays. Moreover, the output stage is composed by a battery energy storage system, dc-ac inverter, LCL filter which enables higher efficiency, low distortion ac waveforms and low leakage currents. The control strategy adopted is cascade control composed by two regulation loops.Simulations performed with PSIM software were able to validate the control system.The realization and testing of the photovoltaic system were achieved in the Photovoltaic laboratory of the Centre for Research and Energy Technologies at the Technopark Borj Cedria. Experimental results verify the effeciency of the proposed system.

  3. Fuzzy Logic Controlled Solar Module for Driving Three- Phase Induction Motor

    International Nuclear Information System (INIS)

    Zainal, Nurul Afiqah; Tat, Chan Sooi; Ajisman

    2016-01-01

    Renewable energy produced by solar module gives advantages for generated three- phase induction motor in remote area. But, solar module's output is uncertain and complex. Fuzzy logic controller is one of controllers that can handle non-linear system and maximum power of solar module. Fuzzy logic controller used for Maximum Power Point Tracking (MPPT) technique to control Pulse-Width Modulation (PWM) for switching power electronics circuit. DC-DC boost converter used to boost up photovoltaic voltage to desired output and supply voltage source inverter which controlled by three-phase PWM generated by microcontroller. IGBT switched Voltage source inverter (VSI) produced alternating current (AC) voltage from direct current (DC) source to control speed of three-phase induction motor from boost converter output. Results showed that, the output power of solar module is optimized and controlled by using fuzzy logic controller. Besides that, the three-phase induction motor can be drive and control using VSI switching by the PWM signal generated by the fuzzy logic controller. This concluded that the non-linear system can be controlled and used in driving three-phase induction motor. (paper)

  4. Fuzzy Logic Controlled Solar Module for Driving Three- Phase Induction Motor

    Science.gov (United States)

    Afiqah Zainal, Nurul; Sooi Tat, Chan; Ajisman

    2016-02-01

    Renewable energy produced by solar module gives advantages for generated three- phase induction motor in remote area. But, solar module's ou tput is uncertain and complex. Fuzzy logic controller is one of controllers that can handle non-linear system and maximum power of solar module. Fuzzy logic controller used for Maximum Power Point Tracking (MPPT) technique to control Pulse-Width Modulation (PWM) for switching power electronics circuit. DC-DC boost converter used to boost up photovoltaic voltage to desired output and supply voltage source inverter which controlled by three-phase PWM generated by microcontroller. IGBT switched Voltage source inverter (VSI) produced alternating current (AC) voltage from direct current (DC) source to control speed of three-phase induction motor from boost converter output. Results showed that, the output power of solar module is optimized and controlled by using fuzzy logic controller. Besides that, the three-phase induction motor can be drive and control using VSI switching by the PWM signal generated by the fuzzy logic controller. This concluded that the non-linear system can be controlled and used in driving three-phase induction motor.

  5. Estimativa de aborto induzido: comparação entre duas metodologias Estimating the frequency of induced abortion: a comparison of two methods

    Directory of Open Access Journals (Sweden)

    Maria Teresa Anselmo Olinto

    2004-05-01

    Full Text Available OBJETIVO: Comparar duas metodologias, o método da urna e o método das questões indiretas, para estimar a freqüência de aborto induzido em estudos de base populacional. MÉTODOS: Foi realizado um estudo transversal de base populacional com uma amostra representativa de 3 002 mulheres de 15 a 49 anos residentes na zona urbana da Cidade de Pelotas, Brasil. As mulheres foram selecionadas através de amostragem de multi-estágios. As questões sobre aborto induzido foram aplicadas utilizando uma das duas metodologias. RESULTADOS: Dentre as mulheres entrevistadas com o método da urna, 7,2% relataram ter induzido pelo menos um aborto, enquanto que para aquelas entrevistadas com o método das questões indiretas esse valor foi de 3,8%. A razão entre os dois métodos foi de 1,89 (IC 95%: 1,39 a 2,60; P OBJECTIVE: To compare two methods-the "ballot box" method and the "indirect questioning" method-for estimating the frequency of induced abortions in population-based studies. METHODS: A cross-sectional population-based study was conducted with a representative sample of 3 002 women between 15 and 49 years of age living in the city of Pelotas, Rio Grande do Sul, Brazil. The women were selected through multistage sampling and randomly assigned to answer questions concerning induced abortion with one of the two methods, after they had answered a general questionnaire that collected socioeconomic and demographic information. With the "ballot box" method, women received a small piece of paper containing direct questions on abortion. Each woman marked her answers on the paper and then deposited it into a small "ballot box" carried by the interviewer, thus assuring the confidentiality of the responses. With the second method, the interviewer verbally asked the woman a series of questions that indirectly inquired about abortion. RESULTS: Among the women assigned to the ballot box method, 7.2% reported having induced at least one abortion, versus 3.8% of the

  6. Structural, optical, magnetic and electrical properties of hematite (α-Fe2O3) nanoparticles synthesized by two methods: polyol and precipitation

    Science.gov (United States)

    Mansour, Houda; Letifi, Hanen; Bargougui, Radhouane; De Almeida-Didry, Sonia; Negulescu, Beatrice; Autret-Lambert, Cécile; Gadri, Abdellatif; Ammar, Salah

    2017-12-01

    Hematite (α-Fe2O3) nanoparticles have been successfully synthesized via two methods: (1) polyol and (2) precipitation in water. The influence of synthesis methods on the crystalline structure, morphological, optical, magnetic and electrical properties were investigated using X-ray diffraction, RAMAN spectroscopy, scanning electron microscopy, transmission electron microscopy, UV-visible diffuse reflectance spectroscopy (UV-vis DRS), superconducting quantum interference device and impedance spectroscopy. The structural properties showed that the obtained hematite α-Fe2O3 nanoparticles with two preparation methods exhibit hexagonal phase with high crystallinity and high-phase stability at room temperature. It was found that the average hematite nanoparticle size is estimated to be 36.86 nm for the sample synthesized by precipitation and 54.14 nm for the sample synthesized by polyol. Moreover, the optical properties showed that the band gap energy value of α-Fe2O3 synthesized by precipitation (2.07 eV) was higher than that of α-Fe2O3 synthesized by polyol (1.97 eV) and they showed a red shift to the visible region. Furthermore, the measurements of magnetic properties indicated a magnetization loop typical of ferromagnetic systems at room temperature. Measurements of electrical properties show higher dielectric permittivity (5.64 × 103) and relaxation phenomenon for α-Fe2O3 issued from the precipitation method than the other sample.

  7. Comparison of Two Methods for the Measurement of Medial and Lateral Metapodial Bones in Karagouniko Sheep (Ovis aries, L. 1758 and Hellenic Goat (Capra hircus, L. 1758

    Directory of Open Access Journals (Sweden)

    Aris Pourlis

    2014-01-01

    Full Text Available The objective of this study was to compare the metapodial lengths of sheep and goats measured with a caliper with those measured using a 2-dimensional digital method. Complementarily, the lengths of medial and lateral metapodials in these species were compared. The limbs of 30 ewes and 30 goats were used. After preparation, the lateral and medial length of the metacarpals and metatarsals were measured twice with a caliper. Afterwards, each bone was scanned and the same lengths were digitally measured twice using commercial software. Data analysis revealed strong linear relationship between the two methods but the absolute relative deviation of the measurements with the caliper was significantly higher than those with the 2-dimensional method (P<0.05. All lengths measured with the caliper were significantly higher compared to those measured with the 2-dimensional method (P<0.05. In goats, the lateral length of both metacarpals and metatarsals was significantly higher than medial length (P<0.05; in sheep the lateral length was significantly higher compared to the medial one only in metatarsal bones (P<0.05. In conclusion, the 2-dimensional method is more accurate for the measurement of the metapodials’ length than the caliper and there is asymmetry between the medial and lateral metapodials in these species.

  8. Comparison of two methods for calculating the mean vascularization index of ovarian stroma on the basis of spatio-temporal image correlation high-definition flow technology.

    Science.gov (United States)

    Kudla, Marek J; Kandzia, Tomasz; Alcázar, Juan Luis

    2013-11-01

    The aim of our study was to determine the agreement between two different methods for calculating the mean vascularization index (VI) of ovarian stroma using spatio-temporal image correlation-high definition flow (STIC-HDF) technology. Stored 4-D STIC-HDF volume data for ovaries of 34 premenopausal women were assessed retrospectively. We calculated the mean VI from the VI values derived for each 3-D volume within the STIC sequence. Then, the examiner subjectively selected the two volumes with the highest and lowest color signals, respectively. We averaged these two values. Agreement between VI measurements was estimated by calculating intra-class correlation coefficients. The intra-class correlation coefficient for the VI was 0.999 (95% confidence interval: 0.999-1.000). The mean time needed to calculate the mean VI using the entire 4-D STIC sequence was significantly longer than the mean time needed to calculate the average value from the volumes with the highest and lowest color signals determined by the operator (p < 0001). We conclude that there is significant agreement between the two methods. Calculating the average VI from the highest and lowest values is less time consuming than calculating the mean VI from the complete STIC sequence. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  9. Complexation efficiency of differently fixed 8-hydroxyquinoline and salicylic acid ligand groups for labile aluminium species determination in soils--comparison of two methods.

    Science.gov (United States)

    Matús, Peter; Kubová, Jana

    2006-07-28

    Two methods utilizing the complexation of labile Al species by 8-hydroxyquinoline (HQN) and salicylic acid (SA) ligand groups were developed for aluminium operationally defined fractionation in acid soils. First, the solid phase extraction (SPE) procedure by a short-term ion-exchange batch reaction with chelating resins Iontosorb Oxin and Iontosorb Salicyl containing both ligand groups was used previously. Second, the 8-hydroxyquinoline, salicylic acid and ammonium salicylate agents with different concentrations by a single extraction protocol were applied in this paper. The flame atomic absorption spectrometry (FAAS) and optical emission spectrometry with inductively coupled plasma were used for aluminium quantification. The comparison of results from both methods show the possibility to supersede the first laborious method for the second simpler one in Al environmental risk assessment. The use of 1% 8-hydroxyquinoline in 2% acetic acid and 0.2% salicylic acid by a single extraction protocol without a need of sample filtration can supersede the SPE procedure in the Al pollution soil monitoring. Finally, the new scheme usable in a laboratory and moreover, directly in a field was proposed for Al fractionation in solid and liquid environmental samples. The labile Al species in soils and sediments are separated after their single leaching by 8-hydroxyquinoline or salicylic acid without a need of sample filtration. The labile Al species in soil solutions and natural waters are separated after their ultrafiltration followed by the SPE procedure with Iontosorb Oxin or Iontosorb Salicyl.

  10. Complexation efficiency of differently fixed 8-hydroxyquinoline and salicylic acid ligand groups for labile aluminium species determination in soils-comparison of two methods

    Energy Technology Data Exchange (ETDEWEB)

    Matus, Peter [Comenius University in Bratislava, Faculty of Natural Sciences, Mlynska dolina, 842 15 Bratislava (Slovakia)]. E-mail: matus@fns.uniba.sk; Kubova, Jana [Comenius University in Bratislava, Faculty of Natural Sciences, Mlynska dolina, 842 15 Bratislava (Slovakia)

    2006-07-28

    Two methods utilizing the complexation of labile Al species by 8-hydroxyquinoline (HQN) and salicylic acid (SA) ligand groups were developed for aluminium operationally defined fractionation in acid soils. First, the solid phase extraction (SPE) procedure by a short-term ion-exchange batch reaction with chelating resins Iontosorb Oxin and Iontosorb Salicyl containing both ligand groups was used previously. Second, the 8-hydroxyquinoline, salicylic acid and ammonium salicylate agents with different concentrations by a single extraction protocol were applied in this paper. The flame atomic absorption spectrometry (FAAS) and optical emission spectrometry with inductively coupled plasma were used for aluminium quantification. The comparison of results from both methods show the possibility to supersede the first laborious method for the second simpler one in Al environmental risk assessment. The use of 1% 8-hydroxyquinoline in 2% acetic acid and 0.2% salicylic acid by a single extraction protocol without a need of sample filtration can supersede the SPE procedure in the Al pollution soil monitoring. Finally, the new scheme usable in a laboratory and moreover, directly in a field was proposed for Al fractionation in solid and liquid environmental samples. The labile Al species in soils and sediments are separated after their single leaching by 8-hydroxyquinoline or salicylic acid without a need of sample filtration. The labile Al species in soil solutions and natural waters are separated after their ultrafiltration followed by the SPE procedure with Iontosorb Oxin or Iontosorb Salicyl.

  11. Comparison of two methods of breeding Holstein heifers, grazing and stabling In the villa maria farm, in firavitoba – Boyacá

    Directory of Open Access Journals (Sweden)

    Jorge Eliécer Plazas Real

    2012-06-01

    Full Text Available The breeding of replacement heifers constitutes one of the biggest challenges of competitive modern farming, especially in the dairy industry, where profitability is given a priority attention. This study compared two rearing systems for Holstein heifers on the “villa María” farm in Firavitoba (Boyacá - Colombia. This town is located in the highland tropic. For the study, 20 years old calves were randomly chosen. They were divided into two equal groups with the same food conditions and under the same study standards. This was done for a period of six months. Two methods of breeding were tested: grazing and stabling. In order to do a respective testing, the calves were weighed with an electric scale and a cattle tape measure for an interval of fifteen days. The data obtained were compared and analyzed to know which breeding method was the most effective. The results showed that the use of the stabling system produced a gain weight increase in the tested subjects, as well as maintenance of management and health conditions that were not observed in other types of rearing systems. Therefore, this system represents a better response in terms of animal wellbeing

  12. Diagnostic of ribeirão Mestre d’Armas sub-basin using two methods of rapid environmental assessment, Federal District, Central Brazil

    Directory of Open Access Journals (Sweden)

    Julio Cesar Joveli

    2010-04-01

    Full Text Available Rapid environmental assessments have been used to describe the quality and semi-quantitative attributes of the ecosystems along an environmental gradient using visual observations and few measurements. The aim of this study was to identify and measure anthropogenic impacts on ribeirão Mestre d’Armas sub-basin, Federal District, Central Brazil, and to propose its environmental zoning. This study was performed using two methods based on rapid environmental assessment: a rapid river assessment protocol, to evaluate in an integrated form the features of a lotic system section according to the conservation or degradation condition of the fluvial environment; and the Leopold matrix, to identify and evaluate the anthropogenic impacts. The environmental zoning of this sub-basin detected three areas: preserved, transition and urban areas. The environmental assessment revealed, the preserved area had lotic stretches with natural features under low magnitude of impacts, except on burned areas. In the transition area, there was a predominance of lotic stretches with altered features, due to agriculture and livestock activities of intermediate level of impacts. Finally, the urban area had altered and impacted lotic stretches of higher magnitude due to anthropogenic impacts. Thus, this study revealed large differences among the areas detected by environmental zoning, according to the methods used. These methods were considered complementary in relation to environmental diagnostic of the ribeirão Mestre d’Armas sub-basin.

  13. Complexation efficiency of differently fixed 8-hydroxyquinoline and salicylic acid ligand groups for labile aluminium species determination in soils-comparison of two methods

    International Nuclear Information System (INIS)

    Matus, Peter; Kubova, Jana

    2006-01-01

    Two methods utilizing the complexation of labile Al species by 8-hydroxyquinoline (HQN) and salicylic acid (SA) ligand groups were developed for aluminium operationally defined fractionation in acid soils. First, the solid phase extraction (SPE) procedure by a short-term ion-exchange batch reaction with chelating resins Iontosorb Oxin and Iontosorb Salicyl containing both ligand groups was used previously. Second, the 8-hydroxyquinoline, salicylic acid and ammonium salicylate agents with different concentrations by a single extraction protocol were applied in this paper. The flame atomic absorption spectrometry (FAAS) and optical emission spectrometry with inductively coupled plasma were used for aluminium quantification. The comparison of results from both methods show the possibility to supersede the first laborious method for the second simpler one in Al environmental risk assessment. The use of 1% 8-hydroxyquinoline in 2% acetic acid and 0.2% salicylic acid by a single extraction protocol without a need of sample filtration can supersede the SPE procedure in the Al pollution soil monitoring. Finally, the new scheme usable in a laboratory and moreover, directly in a field was proposed for Al fractionation in solid and liquid environmental samples. The labile Al species in soils and sediments are separated after their single leaching by 8-hydroxyquinoline or salicylic acid without a need of sample filtration. The labile Al species in soil solutions and natural waters are separated after their ultrafiltration followed by the SPE procedure with Iontosorb Oxin or Iontosorb Salicyl

  14. Eye-rima oris distance and its relation to the vertical dimension of occlusion measured by two methods: Anthropometric study in a sample of Yemeni dental students.

    Science.gov (United States)

    Alhajj, Mohammed Nasser; Khalifa, Nadia; Amran, Abdullah

    2016-01-01

    This study was conducted to evaluate the relationship between the distance measured from the distal outer of the eye to the parting line of the lips and the occlusal vertical dimension (OVD) measured by two methods. One hundred and fourteen dental students (76 males and 38 females) were recruited for this study with mean age (22.34 ± 1.83) years. The distance from distal canthus of the eye to rima oris (eye-RO) was compared with two different measurements of the OVD (nasal [N] to gnathion [Gn], and subnasal [Sn] to menton [Me]). All distances were measured using modified digital caliper. Pearson correlation coefficient test for correlations and paired samples t-test for differences were used with a significant level of (P < 0.05). There was a positive significant correlation between the eye-RO distance and the two measurements of the OVD. However, this correlation was stronger between eye-RO and the distance from the tip of the nose to the tip of the chin than that between eye-RO and the distance from the septum of the nose to the under of the chin (r = 0.313 with P = 0.0007, r = 0.296 with P = 0.0014), respectively. The distance from the outer canthus of the eye to the parting of the lips seems to be a reliable method in predicting the OVD and should relate to the distance from the tip of the nose to the tip of the chin.

  15. A comparison of the antibacterial activity of the two methods of photodynamic therapy (using diode laser 810 nm and LED lamp 630 nm) against Enterococcus faecalis in extracted human anterior teeth.

    Science.gov (United States)

    Asnaashari, Mohammad; Mojahedi, Seyed Masoud; Asadi, Zahra; Azari-Marhabi, Saranaz; Maleki, Alireza

    2016-03-01

    Failure of endodontic treatment is usually due to an inadequate disinfection of the root canal system. Enterococcus faecalis has been widely used as a valuable microbiological marker for in-vitro studies because of its ability to colonize in a biofilm like style in root canals, invading dentinal tubules and resistance to some endodontic treatments. The aim of this study was to investigate the antibacterial effects of two methods of photodynamic therapy using a light emitting diode lamp (LED lamp, 630 nm) and a diode laser (810 nm) on E. faecalis biofilms in anterior extracted human teeth. Fifty six single-rooted extracted teeth were used in this study. After routine root canal cleansing, shaping and sterilization, the teeth were incubated with E. faecalis for a period of two weeks. Teeth were then divided into two experimental groups (nu=23) and two control groups (nu=5). Teeth in one experimental group were exposed to a diode laser (810 nm), and in the other group samples were exposed to a LED lamp (630 nm). Intracanal bacterial sampling was done, and bacterial survival rate was then evaluated for each group. The Colony Forming Unit (CFU) in LED group (log10 CFUs=4.88±0.82) was significantly lower than the laser group (log CFUs=5.49±0.71) (p value=0.021). CFUs in positive control group (Log10 CFUs=10.96±0.44) were significantly higher than the treatment group (p˂0.001). No bacterial colony was found in negative control group. The results of this research show that photodynamic therapy could be an effective supplement in root canal disinfection. PDT using LED lamp was more effective than diode laser 810 nm in reducing CFUs of E. faecalis in human teeth. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Tsunami vulnerability and damage for buildings analyzed by means of two methods (PTVA-3 and SCHEMA) in the area of Augusta and Siracusa, eastern Sicily, Italy

    Science.gov (United States)

    Pagnoni, Gianluca; Tinti, Stefano

    2015-04-01

    The coast of the eastern Sicily is exposed to tsunamis that can be generated by local earthquakes (e.g. the 1169, 1693, 1908 events) and by earthquakes located in distant seismic zones (see the 365 AD tsunamigenic quake in Western Hellenic Arc). Tsunamis can also be generated by landslides possibly triggered by earthquakes. The Hyblean-Malta steep escarpment running offshore at a small angle with the coast is an ideal place for submarine mass failure occurrences with tsunamigenic effects. The entire eastern coast of Sicily from Messina in the north to Siracusa in the south is under the threat of tsunamis. In the frame of the FP7 European project ASTARTE (Assessment, Strategy And Risk Reduction for Tsunamis in Europe - FP7-ENV2013 6.4-3, Grant 603839), the segment of coast from Augusta to Siracusa was selected to undertake specific and detailed studies of tsunami hazard, vulnerability and damage to test existing methods and develop innovative approaches. The scope of the present work regards vulnerability and damage analyses. We chose to adopt two methods, known in the literature and briefly denoted as PTVA-3 and SCHEMA, that are based on two very different approaches, the former more qualitative and the latter more quantitative. The method PTVA-3 determines the vulnerability and damageability of a building by weighting and ranking a number of attributes covering the structural features of the edifice and the relevant characteristics of the surrounding environment such as the position with respect to the coast, the existence of defensive elements (e.g. walls, breakwaters, vegetation) and also the proximity to potential sources of floating objects that can feed damaging debris flows. On the other hand, the SCHEMA method uses a classification of building and a damage matrix that were derived from experimental fragility and damage curves first established after the Sumatra 2004 tsunami and later refined and adapted to the building stock of the Mediterranean region. The

  17. Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter

    Directory of Open Access Journals (Sweden)

    Johan Forslund

    2015-05-01

    Full Text Available This paper investigates three load control methods for a  marine current energy converter using a vertical axis current  turbine (VACT mounted on a permanent magnet synchronous generator  (PMSG. The three cases are; a fixed AC load, a fixed pulse width  modulated (PWM DC load and DC bus voltage control of a DC  load. Experimental results show that the DC bus voltage control  reduces the variations of rotational speed by a factor of 3.5 at the cost  of slightly increased losses in the generator and transmission lines.  For all three cases, the tip speed ratio \\(\\lambda\\ can be kept close to  the expected \\(\\lambda_{opt}\\. The power coefficient is estimated to be  0.36 at \\(\\lambda_{opt}\\; however, for all three cases, the average  extracted power was about \\(\\sim 19\\\\%. A maximum power point  tracking (MPPT system, with or without water velocity measurement,  could increase the average extracted power.

  18. Discrete Model Predictive Control-Based Maximum Power Point Tracking for PV Systems: Overview and Evaluation

    DEFF Research Database (Denmark)

    Lashab, Abderezak; Sera, Dezso; Guerrero, Josep M.

    2018-01-01

    The main objective of this work is to provide an overview and evaluation of discrete model predictive controlbased maximum power point tracking (MPPT) for PV systems. A large number of MPC based MPPT methods have been recently introduced in the literature with very promising performance, however......, an in-depth investigation and comparison of these methods have not been carried out yet. Therefore, this paper has set out to provide an in-depth analysis and evaluation of MPC based MPPT methods applied to various common power converter topologies. The performance of MPC based MPPT is directly linked...... with the converter topology, and it is also affected by the accurate determination of the converter parameters, sensitivity to converter parameter variations is also investigated. The static and dynamic performance of the trackers are assessed according to the EN 50530 standard, using detailed simulation models...

  19. Comparison of two methods of visual magnification for removal of adhesive flash during bracket placement using two types of orthodontic bonding agents

    Science.gov (United States)

    Alencar, Estefania Queiroga de Santana e; Nobrega, Maria de Lourdes Martins; Dametto, Fabio Roberto; dos Santos, Patrícia Bittencourt Dutra; Pinheiro, Fabio Henrique de Sá Leitão

    2016-01-01

    ABSTRACT Objective: This study aimed to evaluate the effectiveness of two methods of visual magnification (operating microscope and light head magnifying glass) for removal of composite flash around orthodontic metal brackets. Material and Methods: Brackets were bonded in the center of the clinical crown of sixty well-preserved human premolars. Half of the sample was bonded with conventional Transbond XT (3M Unitek TM, USA), whereas the other half was bonded with Transbond TM Plus Color Change (3M Unitek TM, USA). For each type of composite, the choice of method to remove the flash was determined by randomly distributing the teeth into the following subgroups: A (removal by naked eye, n = 10), B (removal with the aid of light head magnifying glass, under 4x magnification, n = 10), and C (removal with the aid of an operating microscope, under 40x magnification, n = 10). Brackets were debonded and teeth taken to a scanning electron microscope (SS-x-550, Shimadzu, Japan) for visualization of their buccal surface. Quantification of composite flash was performed with Image Pro Plus software, and values were compared by Kruskal-Wallis test and Dunn’s post-hoc test at 5% significance level. Results: Removal of pigmented orthodontic adhesive with the aid of light head magnifying glass proved, in general, to be advantageous in comparison to all other methods. Conclusion: There was no advantage in using Transbond TM Plus Color Change alone. Further studies are necessary to draw a more definitive conclusion in regards to the benefits of using an operating microscope. PMID:28125139

  20. Comparison of effectiveness of two methods of health education on cancer awareness among adolescent school children in a rural area of Southern India

    Directory of Open Access Journals (Sweden)

    Surekha Anbazhagan

    2016-01-01

    Full Text Available Introduction: Cancer is a major public health problem worldwide. There is an urgent need for a reinvigorated and tailored approach to promote cancer prevention and treatment-related health education, especially among the youth. Objective: (1 To assess the knowledge and awareness of the students of adolescent age group about cancer. (2 To compare two methods of health education on improving awareness about cancer among these students. Methodology: We conducted an interventional study among students (both male and female of adolescent age group (10–19 years who attend Government school (Lakkur and Kugur in Sarjapur PHC between May and September 2014. A standard pretested validated questionnaire-adopted from Cancer Awareness Measure-translated into Kannada was used. After pretest, health education was given by two modes: in Lakkur - child to child, and Kugur - routine (lecture. Following 2 days of health education, an immediate posttest was conducted. After 2 weeks, the second posttest was conducted. Results: In Kugur School, 96 students and Lakkur School, 104 students participated. The mean age group of students in both the schools was 14 years. The preexisting knowledge scores between both the schools were not statistically significant. There was a significant increase in knowledge of the posttest scores in all three domains of cancer questionnaire in both the schools. Child to child program in Lakkur School was found to be more effective in increasing the knowledge scores. Conclusion: To increase the awareness of cancer among schools using child to child method for health education. School curriculum should include sessions on cancer education and reinforced to students periodically. To sustain this measure, school teachers could be trained in nuances of cancer prevention and treatment.

  1. Comparison of effectiveness of two methods of health education on cancer awareness among adolescent school children in a rural area of Southern India.

    Science.gov (United States)

    Anbazhagan, Surekha; Shanbhag, Deepthi; Antony, Anu; Bhanuprakash, Kypoo; Anbazhagan, Suguna; Chandran, Niresh; Ramakrishna, Goud

    2016-01-01

    Cancer is a major public health problem worldwide. There is an urgent need for a reinvigorated and tailored approach to promote cancer prevention and treatment-related health education, especially among the youth. (1) To assess the knowledge and awareness of the students of adolescent age group about cancer. (2) To compare two methods of health education on improving awareness about cancer among these students. We conducted an interventional study among students (both male and female) of adolescent age group (10-19 years) who attend Government school (Lakkur and Kugur) in Sarjapur PHC between May and September 2014. A standard pretested validated questionnaire-adopted from Cancer Awareness Measure-translated into Kannada was used. After pretest, health education was given by two modes: in Lakkur - child to child, and Kugur - routine (lecture). Following 2 days of health education, an immediate posttest was conducted. After 2 weeks, the second posttest was conducted. In Kugur School, 96 students and Lakkur School, 104 students participated. The mean age group of students in both the schools was 14 years. The preexisting knowledge scores between both the schools were not statistically significant. There was a significant increase in knowledge of the posttest scores in all three domains of cancer questionnaire in both the schools. Child to child program in Lakkur School was found to be more effective in increasing the knowledge scores. To increase the awareness of cancer among schools using child to child method for health education. School curriculum should include sessions on cancer education and reinforced to students periodically. To sustain this measure, school teachers could be trained in nuances of cancer prevention and treatment.

  2. Bone Apparent and Material Densities Examined by Cone Beam Computed Tomography and the Archimedes Technique: Comparison of the Two Methods and Their Results

    Directory of Open Access Journals (Sweden)

    George J. Adams

    2018-02-01

    Full Text Available An understanding of bone apparent and material densities and how they vary within bone at the organ level is of great interest in the understanding of degenerative bone conditions and for biomedical engineering applications. The densities of bone tissue have been shown to appreciably influence the mechanical competency of bone tissue. In order to assess the density of bone in the body, it is important to ensure that the parameters being measured in vivo are truly representative of the real values that have been measured in vitro. To assess the densities of bone across the entire spectrum of available porosities, 112 samples from an elephant femur were assessed using the Archimedes method (water displacement and by micro-computed tomography (μ-CT. Comparisons were drawn between the two methods to determine if the densities calculated by μ-CT were representative of physically measured densities. The results showed that the apparent densities measured over the entire spectrum were very similar but varied in the intermediate regions of bone tissue, probably due to an increased presence of osteoid, increased remodeling, or experimental error as these type of bone is known for the presence of regions of closed cell geometry in the cancellous architecture. It could be argued that the measurements taken by μ-CT are more reliable of bone density values for the mineralized regions of bone as the threshold is defined with respect to the absorption of X-rays by the mineral. In contrast, the Archimedes method thresholds everything with a density value above that of the surrounding medium, 1 (g cm−3 for water, and hence it is more sensitive to the presence of osteoid, soft collagenous matrix, and epithelial cell layers. Further research is required to optimize the parameters of scanning methods for the structural properties of different bone tissue porosities, which hopefully in turn will be able to provide a basis for the development of predictive

  3. Parameter Improved Particle Swarm Optimization Based Direct-Current Vector Control Strategy for Solar PV System

    Directory of Open Access Journals (Sweden)

    NAMMALVAR, P.

    2018-02-01

    Full Text Available This paper projects Parameter Improved Particle Swarm Optimization (PIPSO based direct current vector control technology for the integration of photovoltaic array in an AC micro-grid to enhance the system performance and stability. A photovoltaic system incorporated with AC micro-grid is taken as the pursuit of research study. The test system features two power converters namely, PV side converter which consists of DC-DC boost converter with Perturbation and Observe (P&O MPPT control to reap most extreme power from the PV array, and grid side converter which consists of Grid Side-Voltage Source Converter (GS-VSC with proposed direct current vector control strategy. The gain of the proposed controller is chosen from a set of three values obtained using apriori test and tuned through the PIPSO algorithm so that the Integral of Time multiplied Absolute Error (ITAE between the actual and the desired DC link capacitor voltage reaches a minimum and allows the system to extract maximum power from PV system, whereas the existing d-q control strategy is found to perform slowly to control the DC link voltage under varying solar insolation and load fluctuations. From simulation results, it is evident that the proposed optimal control technique provides robust control and improved efficiency.

  4. Hybrid Intelligent Control Method to Improve the Frequency Support Capability of Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Shin Young Heo

    2015-10-01

    Full Text Available This paper presents a hybrid intelligent control method that enables frequency support control for permanent magnet synchronous generators (PMSGs wind turbines. The proposed method for a wind energy conversion system (WECS is designed to have PMSG modeling and full-scale back-to-back insulated-gate bipolar transistor (IGBT converters comprising the machine and grid side. The controller of the machine side converter (MSC and the grid side converter (GSC are designed to achieve maximum power point tracking (MPPT based on an improved hill climb searching (IHCS control algorithm and de-loaded (DL operation to obtain a power margin. Along with this comprehensive control of maximum power tracking mode based on the IHCS, a method for kinetic energy (KE discharge control of the supporting primary frequency control scheme with DL operation is developed to regulate the short-term frequency response and maintain reliable operation of the power system. The effectiveness of the hybrid intelligent control method is verified by a numerical simulation in PSCAD/EMTDC. Simulation results show that the proposed approach can improve the frequency regulation capability in the power system.

  5. Application of Fuzzy Control in a Photovoltaic Grid-Connected Inverter

    Directory of Open Access Journals (Sweden)

    Zhaohong Zheng

    2018-01-01

    Full Text Available To realize the maximum power output of a grid-connected inverter, the MPPT (maximum power point tracking control method is needed. The perturbation and observation (P&O method can cause the inverter operating point to oscillate near the maximum power. In this paper, the fuzzy control P&O method is proposed, and the fuzzy control algorithm is applied to the disturbance observation method. The simulation results of the P&O method with fuzzy control and the traditional P&O method prove that not only can the new method reduce the power loss caused by inverter oscillation during maximum power point tracking, but also it has the advantage of speed. Inductive loads in the post-grid-connected stage cause grid-connected current distortion. A fuzzy control algorithm is added to the traditional deadbeat grid-connected control method to improve the quality of the system’s grid-connected operation. The fuzzy deadbeat control method is verified by experiments, and the harmonic current of the grid-connected current is less than 3%.

  6. Control Strategies for the DAB Based PV Interface System.

    Directory of Open Access Journals (Sweden)

    Hadi M El-Helw

    Full Text Available This paper presents an interface system based on the Dual Active Bridge (DAB converter for Photovoltaic (PV arrays. Two control strategies are proposed for the DAB converter to harvest the maximum power from the PV array. The first strategy is based on a simple PI controller to regulate the terminal PV voltage through the phase shift angle of the DAB converter. The Perturb and Observe (P&O Maximum Power Point Tracking (MPPT technique is utilized to set the reference of the PV terminal voltage. The second strategy presented in this paper employs the Artificial Neural Network (ANN to directly set the phase shift angle of the DAB converter that results in harvesting maximum power. This feed-forward strategy overcomes the stability issues of the feedback strategy. The proposed PV interface systems are modeled and simulated using MATLAB/SIMULINK and the EMTDC/PSCAD software packages. The simulation results reveal accurate and fast response of the proposed systems. The dynamic performance of the proposed feed-forward strategy outdoes that of the feedback strategy in terms of accuracy and response time. Moreover, an experimental prototype is built to test and validate the proposed PV interface system.

  7. Control Strategies for the DAB Based PV Interface System.

    Science.gov (United States)

    El-Helw, Hadi M; Al-Hasheem, Mohamed; Marei, Mostafa I

    2016-01-01

    This paper presents an interface system based on the Dual Active Bridge (DAB) converter for Photovoltaic (PV) arrays. Two control strategies are proposed for the DAB converter to harvest the maximum power from the PV array. The first strategy is based on a simple PI controller to regulate the terminal PV voltage through the phase shift angle of the DAB converter. The Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) technique is utilized to set the reference of the PV terminal voltage. The second strategy presented in this paper employs the Artificial Neural Network (ANN) to directly set the phase shift angle of the DAB converter that results in harvesting maximum power. This feed-forward strategy overcomes the stability issues of the feedback strategy. The proposed PV interface systems are modeled and simulated using MATLAB/SIMULINK and the EMTDC/PSCAD software packages. The simulation results reveal accurate and fast response of the proposed systems. The dynamic performance of the proposed feed-forward strategy outdoes that of the feedback strategy in terms of accuracy and response time. Moreover, an experimental prototype is built to test and validate the proposed PV interface system.

  8. Comparison of two methods for minimizing the effect of delayed charge on the dose delivered with a synchrotron based discrete spot scanning proton beam

    International Nuclear Information System (INIS)

    Whitaker, Thomas J.; Beltran, Chris; Tryggestad, Erik; Kruse, Jon J.; Remmes, Nicholas B.; Tasson, Alexandria; Herman, Michael G.; Bues, Martin

    2014-01-01

    Purpose: Delayed charge is a small amount of charge that is delivered to the patient after the planned irradiation is halted, which may degrade the quality of the treatment by delivering unwarranted dose to the patient. This study compares two methods for minimizing the effect of delayed charge on the dose delivered with a synchrotron based discrete spot scanning proton beam. Methods: The delivery of several treatment plans was simulated by applying a normally distributed value of delayed charge, with a mean of 0.001(SD 0.00025) MU, to each spot. Two correction methods were used to account for the delayed charge. Method one (CM1), which is in active clinical use, accounts for the delayed charge by adjusting the MU of the current spot based on the cumulative MU. Method two (CM2) in addition reduces the planned MU by a predicted value. Every fraction of a treatment was simulated using each method and then recomputed in the treatment planning system. The dose difference between the original plan and the sum of the simulated fractions was evaluated. Both methods were tested in a water phantom with a single beam and simple target geometry. Two separate phantom tests were performed. In one test the dose per fraction was varied from 0.5 to 2 Gy using 25 fractions per plan. In the other test the number fractions were varied from 1 to 25, using 2 Gy per fraction. Three patient plans were used to determine the effect of delayed charge on the delivered dose under realistic clinical conditions. The order of spot delivery using CM1 was investigated by randomly selecting the starting spot for each layer, and by alternating per layer the starting spot from first to last. Only discrete spot scanning was considered in this study. Results: Using the phantom setup and varying the dose per fraction, the maximum dose difference for each plan of 25 fractions was 0.37–0.39 Gy and 0.03–0.05 Gy for CM1 and CM2, respectively. While varying the total number of fractions, the maximum dose

  9. Optimal Control and Operation Strategy for Wind Turbines Contributing to Grid Primary Frequency Regulation

    Directory of Open Access Journals (Sweden)

    Mun-Kyeom Kim

    2017-09-01

    Full Text Available This study introduces a frequency regulation strategy to enable the participation of wind turbines with permanent magnet synchronous generators (PMSGs. The optimal strategy focuses on developing the frequency support capability of PMSGs connected to the power system. Active power control is performed using maximum power point tracking (MPPT and de-loaded control to supply the required power reserve following a disturbance. A kinetic energy (KE reserve control is developed to enhance the frequency regulation capability of wind turbines. The coordination with the de-loaded control prevents instability in the PMSG wind system due to excessive KE discharge. A KE optimization method that maximizes the sum of the KE reserves at wind farms is also adopted to determine the de-loaded power reference for each PMSG wind turbine using the particle swarm optimization (PSO algorithm. To validate the effectiveness of the proposed optimal control and operation strategy, three different case studies are conducted using the PSCAD/EMTDC simulation tool. The results demonstrate that the optimal strategy enhances the frequency support contribution from PMSG wind turbines.

  10. Modified Perfect Harmonics Cancellation Control of a Grid Interfaced SPV Power Generation

    Science.gov (United States)

    Singh, B.; Shahani, D. T.; Verma, A. K.

    2015-03-01

    This paper deals with a grid interfaced solar photo voltaic (SPV) power generating system with modified perfect harmonic cancellation (MPHC) control for power quality improvement in terms of mitigation of the current harmonics, power factor correction, control of point of common coupling (PCC) voltage with reactive power compensation and load balancing in a three phase distribution system. The proposed grid interfaced SPV system consists of a SPV array, a dc-dc boost converter and a voltage source converter (VSC) used for the compensation of other connected linear and nonlinear loads at PCC. The reference grid currents are estimated using MPHC method and control signals are derived by using pulse width modulation (PWM) current controller of VSC. The SPV power is fed to the common dc bus of VSC and dc-dc boost converter using maximum power point tracking (MPPT). The dc link voltage of VSC is regulated by using dc voltage proportional integral (PI) controller. The analysis of the proposed SPV power generating system is carried out under dc/ac short circuit and severe SPV-SX and SPV-TX intrusion.

  11. Detailed assessment of low-back loads may not be worth the effort: A comparison of two methods for exposure-outcome assessment of low-back pain.

    Science.gov (United States)

    Coenen, Pieter; Kingma, Idsart; Boot, Cécile R L; Bongers, Paulien M; van Dieën, Jaap H

    2015-11-01

    The trade-off between feasibility and accuracy of measurements of physical exposure at the workplace has often been discussed, but is unsufficiently understood. We therefore explored the effect of two low-back loading measurement tools with different accuracies on exposure estimates and their associations with low-back pain (LBP). Low-back moments of 93 workers were obtained using two methods: a moderately accurate observation-based method and a relatively more accurate video-analysis method. Group-based exposure metrics were assigned to a total of 1131 workers who reported on their LBP status during three follow-up years. The two methods were compared regarding individual and group-based moments and their predictive value for LBP. Differences between the two methods for peak moments were high at the individual level and remained substantial at group level. For cumulative moments, differences between the two methods were attenuated as random inaccuracies cancelled out. Peak moments were not predictive for LBP in any method while cumulative moments were, suggesting comparable predictive values of the two methods. While assessment of low-back load improves from investing in collecting relatively more accurate individual-based data, this does not necessarily lead to better predictive values on a group level, especially not for cumulative loads. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  12. New MPPT algorithm based on hybrid dynamical theory

    KAUST Repository

    Elmetennani, Shahrazed

    2014-11-01

    This paper presents a new maximum power point tracking algorithm based on the hybrid dynamical theory. A multiceli converter has been considered as an adaptation stage for the photovoltaic chain. The proposed algorithm is a hybrid automata switching between eight different operating modes, which has been validated by simulation tests under different working conditions. © 2014 IEEE.

  13. Robust fractional order sliding mode control of doubly-fed induction generator (DFIG)-based wind turbines.

    Science.gov (United States)

    Ebrahimkhani, Sadegh

    2016-07-01

    Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  14. Comparison of Effect of Two Methods of Face-to-Face Education and Distance Education (via Short Message Service on Amount of Following Remedial Diet in Patients Suffering From Hypertension

    Directory of Open Access Journals (Sweden)

    Basiri

    2016-04-01

    Full Text Available Background A large amount of money is allocated to hypertension in terms of remedial and care costs, but fighting against this disease begins with education. Objectives This study has been conducted with the aim of comparing the effect of two methods: face-to-face education and distance education (via short message service [SMS] on amount of following remedial diet in patients suffering from hypertension. Patients and Methods In this clinical trial study, 72 patients who were suffering from hypertension participated. They were selected by the purposeful sampling from three hospitals in Abadan city, Iran. Each of the three groups were similar in terms of age, gender, level of education, marital status, and duration of suffering from hypertension. The first group was under face-to-face education for eight sessions of 30 minutes; the second group under distance education (via SMS; and the third group did not receive any education as they were the control group. The tools used for collecting data involved three questionnaires (demographic data [two parts], following medicinal diet (three parts: MMAS-3, therapeutic lifestyle changes, and dietary approach to stop hypertension, and evaluating the amount of patients’ awareness about their disease. This study applied descriptive and deductive statistics with SPSS Version 20 for statistical analysis. Results The results showed that the mean of examined realms, after interference in both the face-to-face and the distance education groups, had a significant statistical difference with the before-interference mean (P = 0.0001. Inter-group comparison between systolic and diastolic blood pressure and awareness realms showed that there was a significant statistical difference between the face-to-face education group compared with the control group (P < 0.05. However, in other realms, no significant statistical difference was observed between the two educational groups (P < 0.05. Conclusions Having access to

  15. The effect of marriage on young adult heavy drinking and its mediators: results from two methods of adjusting for selection into marriage.

    Science.gov (United States)

    Lee, Matthew R; Chassin, Laurie; Mackinnon, David

    2010-12-01

    This study tested the effect of marriage on young adult heavy drinking and tested whether this effect was mediated by involvement in social activities, religiosity, and self-control reasons for limiting drinking. The sample of 508 young adults was taken from an ongoing longitudinal study of familial alcoholism that over-sampled children of alcoholics (Chassin, Rogosch, & Barrera, 1991). In order to distinguish role socialization effects of marriage from confounding effects of role selection into marriage, analyses used both the analysis of covariance (ANCOVA) method and the change score method of adjusting for pre-marriage levels of heavy drinking and the mediators. Results showed role socialization effects of marriage on post-marriage declines in heavy drinking. This effect was mediated by involvement in social activities such that marriage predicted decreased involvement in social activities, which in turn predicted decreased heavy drinking. There were no statistically significant mediated effects of religiosity. The mediated effect of self-control reasons for limiting drinking was supported by the ANCOVA method only, and further investigation suggested that this result was detected erroneously due to violation of an assumption of the ANCOVA method that is not shared by the change score method. Findings from this study offer an explanation for the maturing out of heavy drinking that takes place for some individuals over the course of young adulthood. Methodologically, results suggest that the ANCOVA method should be employed with caution, and that the change score method is a viable approach to confirming results from the ANCOVA method. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

  16. The Comparison of Two Methods of Exercise (intense interval training and concurrent resistance- endurance training on Fasting Sugar, Insulin and Insulin Resistance in Women with Mellitus Diabetes

    Directory of Open Access Journals (Sweden)

    F Bazyar

    2016-05-01

    Full Text Available Background & aim: Exercise is an important component of health and an integral approach to the management of diabetes mellitus. The purpose of this study was to compare the effects of intense interval training and concurrent resistance- endurance training on fasting sugar, insulin and insulin resistance in women with mellitus diabetes.   Methods: Fifty-two overweight female diabetic type 2 patients (aged 45-60 years old with fasting blood glucose≥ 126 mg/dl were selected to participate in the present study. Participants were assigned to intense interval training group (N=17, concurrent resistance- endurance training group (N=17 and control group (N=18. The exercises incorporated 10 weeks of concurrent resistance- endurance training and intense interval training. Fasting blood sugar, serum insulin concentrations levels were measured. Concurrent training group trained eight weeks, three times a week of endurance training at 60% of maximum heart rate (MHR and two resistance training sessions per week with 70% of one repetition maximum (1-RM. Intense interval training group trained for eight weeks, three sessions per week for 4 to 10 repeats Wingate test on the ergometer 30s performed with maximum effort. The control group did no systematic exercise. At the end of experiment 42 subjects were succeed and completed the study period, and 10 subjects were removed due to illness and absence in the exercise sessions. Fasting blood sugar and insulin levels 24 hours before and 48 hours after the last training session was measured.   Results: The findings indicated that in periodic fasting, the blood sugar in intensive training group had a marked decrease (p= 0.000 however, the fasting blood sugar of exercise and power stamina groups reduced significantly (p=0.062. The results showed no significant difference between the groups (171/0 p =0.171. Fasting insulin (p <0.001 and insulin resistance (0001/0 = p=0.001 in periodic intensive training group were

  17. A comparison between the two methods of chest compression in infant and neonatal resuscitation. A review according to 2010 CPR guidelines.

    Science.gov (United States)

    Douvanas, Alexandros; Koulouglioti, Christina; Kalafati, Maria

    2018-03-01

    The quality of chest compression (CC) delivered during neonatal and infant cardiopulmonary resuscitation (CPR) is identified as the most important factor to achieve the increase of survival rate without major neurological deficit to the patients. The objective of the study was to systematically review all the available studies that have compared the two different techniques of hand placement on infants and neonatal resuscitation, from 2010 to 2015 and to highlight which method is more effective. A review of the literature using a variety of medical databases, including Cochrane, MEDLINE, and SCOPUS electronic databases. The following MeSH terms were used in the search: infant, neonatal, CPR, CC, two-thumb (TT) technique/method, two-finger (TF) technique/method, rescuer fatigue, thumb/finger position/placement, as well as combinations of these. Ten studies met the inclusion criteria; nine observational studies and a randomized controlled trial. All providers performed either continuous TF or TT technique CCs and the majority of CPR performance was taken place in infant trainer manikin. The majority of the studies suggest the TT method as the more useful for infants and neonatal resuscitation than the TF.

  18. Comparison of P&O and INC Methods in Maximum Power Point Tracker for PV Systems

    Science.gov (United States)

    Chen, Hesheng; Cui, Yuanhui; Zhao, Yue; Wang, Zhisen

    2018-03-01

    In the context of renewable energy, the maximum power point tracker (MPPT) is often used to increase the solar power efficiency, taking into account the randomness and volatility of solar energy due to changes in temperature and photovoltaic. In all MPPT techniques, perturb & observe and incremental conductance are widely used in MPPT controllers, because of their simplicity and ease of operation. According to the internal structure of the photovoltaic cell and the output volt-ampere characteristic, this paper established the circuit model and establishes the dynamic simulation model in Matlab/Simulink with the preparation of the s function. The perturb & observe MPPT method and the incremental conductance MPPT method were analyzed and compared by the theoretical analysis and digital simulation. The simulation results have shown that the system with INC MPPT method has better dynamic performance and improves the output power of photovoltaic power generation.

  19. Adaptive control paradigm for photovoltaic and solid oxide fuel cell in a grid-integrated hybrid renewable energy system

    Science.gov (United States)

    Khan, Laiq

    2017-01-01

    The hybrid power system (HPS) is an emerging power generation scheme due to the plentiful availability of renewable energy sources. Renewable energy sources are characterized as highly intermittent in nature due to meteorological conditions, while the domestic load also behaves in a quite uncertain manner. In this scenario, to maintain the balance between generation and load, the development of an intelligent and adaptive control algorithm has preoccupied power engineers and researchers. This paper proposes a Hermite wavelet embedded NeuroFuzzy indirect adaptive MPPT (maximum power point tracking) control of photovoltaic (PV) systems to extract maximum power and a Hermite wavelet incorporated NeuroFuzzy indirect adaptive control of Solid Oxide Fuel Cells (SOFC) to obtain a swift response in a grid-connected hybrid power system. A comprehensive simulation testbed for a grid-connected hybrid power system (wind turbine, PV cells, SOFC, electrolyzer, battery storage system, supercapacitor (SC), micro-turbine (MT) and domestic load) is developed in Matlab/Simulink. The robustness and superiority of the proposed indirect adaptive control paradigm are evaluated through simulation results in a grid-connected hybrid power system testbed by comparison with a conventional PI (proportional and integral) control system. The simulation results verify the effectiveness of the proposed control paradigm. PMID:28329015

  20. Adaptive control paradigm for photovoltaic and solid oxide fuel cell in a grid-integrated hybrid renewable energy system.

    Science.gov (United States)

    Mumtaz, Sidra; Khan, Laiq

    2017-01-01

    The hybrid power system (HPS) is an emerging power generation scheme due to the plentiful availability of renewable energy sources. Renewable energy sources are characterized as highly intermittent in nature due to meteorological conditions, while the domestic load also behaves in a quite uncertain manner. In this scenario, to maintain the balance between generation and load, the development of an intelligent and adaptive control algorithm has preoccupied power engineers and researchers. This paper proposes a Hermite wavelet embedded NeuroFuzzy indirect adaptive MPPT (maximum power point tracking) control of photovoltaic (PV) systems to extract maximum power and a Hermite wavelet incorporated NeuroFuzzy indirect adaptive control of Solid Oxide Fuel Cells (SOFC) to obtain a swift response in a grid-connected hybrid power system. A comprehensive simulation testbed for a grid-connected hybrid power system (wind turbine, PV cells, SOFC, electrolyzer, battery storage system, supercapacitor (SC), micro-turbine (MT) and domestic load) is developed in Matlab/Simulink. The robustness and superiority of the proposed indirect adaptive control paradigm are evaluated through simulation results in a grid-connected hybrid power system testbed by comparison with a conventional PI (proportional and integral) control system. The simulation results verify the effectiveness of the proposed control paradigm.

  1. Comparison of two methods: TBL-based and lecture-based learning in nursing care of patients with diabetes in nursing students

    Directory of Open Access Journals (Sweden)

    Masoud Khodaveisi

    2016-08-01

    Full Text Available Learning plays an important role in developing nursing skills and right care-taking. The Present study aims to evaluate two learning methods based on team –based learning and lecture-based learning in learning care-taking of patients with diabetes in nursing students. In this quasi-experimental study, 64 students in term 4 in nursing college of Bukan and Miandoab were included in the study based on knowledge and performance questionnaire including 15 questions based on knowledge and 5 questions based on performance on care-taking in patients with diabetes were used as data collection tool whose reliability was confirmed by cronbach alpha (r=0.83 by the researcher. To compare the mean score of knowledge and performance in each group in pre-test step and post-test step, pair –t test and to compare mean of scores in two groups of control and intervention, the independent t- test was used. There was not significant statistical difference between two groups in pre terms of knowledge and performance score (p=0.784. There was significant difference between the mean of knowledge scores and diabetes performance in the post-test in the team-based learning group and lecture-based learning group (p=0.001. There was significant difference between the mean score of knowledge of diabetes care in pre-test and post-test in base learning groups (p=0.001. In both methods team-based and lecture-based learning approaches resulted in improvement in learning in students, but the rate of learning in the team-based learning approach is greater compared to that of lecturebased learning and it is recommended that this method be used as a higher education method in the education of students.

  2. 37: COMPARISON OF TWO METHODS: TBL-BASED AND LECTURE-BASED LEARNING IN NURSING CARE OF PATIENTS WITH DIABETES IN NURSING STUDENTS

    Science.gov (United States)

    Khodaveisi, Masoud; Qaderian, Khosro; Oshvandi, Khodayar; Soltanian, Ali Reza; Vardanjani, Mehdi molavi

    2017-01-01

    Background and aims learning plays an important role in developing nursing skills and right care-taking. The Present study aims to evaluate two learning methods based on team –based learning and lecture-based learning in learning care-taking of patients with diabetes in nursing students. Method In this quasi-experimental study, 64 students in term 4 in nursing college of Bukan and Miandoab were included in the study based on knowledge and performance questionnaire including 15 questions based on knowledge and 5 questions based on performance on care-taking in patients with diabetes were used as data collection tool whose reliability was confirmed by cronbach alpha (r=0.83) by the researcher. To compare the mean score of knowledge and performance in each group in pre-test step and post-test step, pair –t test and to compare mean of scores in two groups of control and intervention, the independent t- test was used. Results There was not significant statistical difference between two groups in pre terms of knowledge and performance score (p=0.784). There was significant difference between the mean of knowledge scores and diabetes performance in the post-test in the team-based learning group and lecture-based learning group (p=0.001). There was significant difference between the mean score of knowledge of diabetes care in pre-test and post-test in base learning groups (p=0.001). Conclusion In both methods team-based and lecture-based learning approaches resulted in improvement in learning in students, but the rate of learning in the team-based learning approach is greater compared to that of lecture-based learning and it is recommended that this method be used as a higher education method in the education of students.

  3. The place of counter discourse in two methods of public deliberation: the conférence de citoyens and the débat public on nanotechnologies in France

    NARCIS (Netherlands)

    Doury, M.; Tseronis, A.

    2013-01-01

    In this paper, we examine two methods of public participation, namely consensus conference (conférence de citoyens) and public hearing (débat public). While both methods are used in order to involve the public in decision making about science and technology policy, they differ in a number of

  4. Sliding Mode Real-Time Control of Photovoltaic Systems Using Neural Estimators

    Directory of Open Access Journals (Sweden)

    J. A. Ramos-Hernanz

    2016-01-01

    Full Text Available The maximum power point tracking (MPPT problem has attracted the attention of many researchers, because it is convenient to obtain the maximum power of a photovoltaic module regardless of the weather conditions and the load. In this paper, a novel control for a boost DC/DC converter has been introduced. It is based on a sliding mode controller (SMC that takes a current signal as reference instead of a voltage, which is generated by a neuronal reference current generator. That reference current indicates the current (IMPP at the maximum power point (MPP for given weather conditions. In order to test the designed control system, a photovoltaic module model based on a second artificial neuronal network (ANN has been obtained from experimental data gathered during 18 months in the Faculty of Engineering Vitoria-Gasteiz (Spain. We have analyzed the performance of such model and we found that it is very accurate (MSE = 0.062 A and R = 0.991 with test dataset. We also have tested the performance of the overall SMC design with both simulated and real tests, concluding that it guarantees that the power in the output of the converter is very close to the power of the photovoltaic module output.

  5. A Digital Coreless Maximum Power Point Tracking Circuit for Thermoelectric Generators

    Science.gov (United States)

    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.

  6. Solar Photovoltaic (PV) Distributed Generation Systems - Control and Protection

    Science.gov (United States)

    Yi, Zhehan

    This dissertation proposes a comprehensive control, power management, and fault detection strategy for solar photovoltaic (PV) distribution generations. Battery storages are typically employed in PV systems to mitigate the power fluctuation caused by unstable solar irradiance. With AC and DC loads, a PV-battery system can be treated as a hybrid microgrid which contains both DC and AC power resources and buses. In this thesis, a control power and management system (CAPMS) for PV-battery hybrid microgrid is proposed, which provides 1) the DC and AC bus voltage and AC frequency regulating scheme and controllers designed to track set points; 2) a power flow management strategy in the hybrid microgrid to achieve system generation and demand balance in both grid-connected and islanded modes; 3) smooth transition control during grid reconnection by frequency and phase synchronization control between the main grid and microgrid. Due to the increasing demands for PV power, scales of PV systems are getting larger and fault detection in PV arrays becomes challenging. High-impedance faults, low-mismatch faults, and faults occurred in low irradiance conditions tend to be hidden due to low fault currents, particularly, when a PV maximum power point tracking (MPPT) algorithm is in-service. If remain undetected, these faults can considerably lower the output energy of solar systems, damage the panels, and potentially cause fire hazards. In this dissertation, fault detection challenges in PV arrays are analyzed in depth, considering the crossing relations among the characteristics of PV, interactions with MPPT algorithms, and the nature of solar irradiance. Two fault detection schemes are then designed as attempts to address these technical issues, which detect faults inside PV arrays accurately even under challenging circumstances, e.g., faults in low irradiance conditions or high-impedance faults. Taking advantage of multi-resolution signal decomposition (MSD), a powerful signal

  7. Augmented Nonlinear Controller for Maximum Power-Point Tracking with Artificial Neural Network in Grid-Connected Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    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.

  8. Home-Based Leg Strengthening Exercise Improves Function One Year After Hip Fracture: A Randomized Controlled Study

    Science.gov (United States)

    Mangione, Kathleen K.; Craik, Rebecca L.; Palombaro, Kerstin M.; Tomlinson, Susan S.; Hofmann, Mary T.

    2010-01-01

    Objectives Examine the effectiveness of a short term leg strengthening exercise program compared to attentional control on improving strength, walking abilities, and function one year after hip fracture. Design Randomized controlled pilot study. Setting Interventions occurred in patients’ homes. Participants Community-dwelling older adults (n=26) six months post hip fracture at baseline. Intervention Exercise and control participants received interventions by physical therapists twice weekly for 10 weeks. The exercise group received high intensity leg strengthening exercises. The control group received transcutaneous electrical nerve stimulation and mental imagery. Measurements Isometric force production of lower extremity muscles; usual and fast gait speed, six minute walk (6-MW) distance, modified physical performance test (mPPT), and SF-36 physical function. Results The primary endpoint was at one year post fracture. Isometric force production (pmPPT (pmPPT scores, 0.56 for gait speed, 0.49 for 6-MW, and 0.30 for SF-36 scores. More patients in the exercise group made meaningful changes in gait speed and 6-MW distance than control patients (χ2: p=.004). Conclusion A 10-week home-based progressive resistance exercise program was sufficient to achieve moderate to large effects on physical performance and quality of life and may offer an alternative intervention mode for hip fracture patients who are unable to leave home at 6 months after the fracture. The effects were maintained at 3 months after completion of the training program. PMID:20929467

  9. Avaliação comparativa entre dois métodos para determinação do colesterol em carnes e leite Comparative evalution of two methods for the determination of cholesterol in meat and milk

    Directory of Open Access Journals (Sweden)

    Tatiana Saldanha

    2004-03-01

    Full Text Available O presente trabalho teve como objetivo comparar duas metodologias, enzimática e por cromatografia líquida de alta eficiência (CLAE, na determinação dos teores de colesterol em amostras de carne bovina e leite. No método por CLAE utilizou-se coluna C18, 100 x 4,6mm x 4µm (Chromolith, Merck, fase móvel acetonitrila:isopropanol (85:15 para as amostras de carne e 95:05 para amostras de leite e detector UV-Visível fixado a 210nm. No método enzimático, a absorbância das amostras foi lida em espectrofotômetro a 499nm, 90 minutos após a reação. Foram realizadas 10 análises de cada produto para as duas metodologias avaliadas, sendo que os resultados obtidos mostraram-se semelhantes (p>0,01. Obteve-se recuperação de 95% para as amostras de carne e 97% para as amostras de leite em ambos os métodos. Os resultados obtidos com o material de referência certificado de carne (SRM 1546, NIST apresentaram-se semelhantes ao declarado no certificado. O coeficiente de variação nas amostras de leite foi de 0,81 e 0,82%, e nas amostras de carne 2,3 e 2,9% para as metodologias cromatográfica e enzimática, respectivamente. O método enzimático mostrou-se sensível e preciso, entretanto, ao contrário da metodologia cromatográfica, necessita de controle rigoroso das condições de análise.The objective of this work was to compare two methods, one enzymatic and the other chromatographic using HPLC, for the determination of cholesterol in meat and milk. For the chromatographic method, a C18 column, 100 x 4.6mm, 4µm (Chromolith, Merck, was used, acetonitrile:isopropanol as the mobile phase (85:15 for samples of meat and 95:05 for samples of milk, a flow rate of 2mL/min and detection by UV-Visible at 210nm. In the enzymatic method, absorbance was read against the blank at 499nm, 90 minutes after the reaction. Each product was analyzed ten times with each methodology, the results being similar (p>0.01. The mean recovery was 95% for the meat samples

  10. Fuzzy logic control of stand-alone photovoltaic system with battery storage

    Science.gov (United States)

    Lalouni, S.; Rekioua, D.; Rekioua, T.; Matagne, E.

    Photovoltaic energy has nowadays an increased importance in electrical power applications, since it is considered as an essentially inexhaustible and broadly available energy resource. However, the output power provided via the photovoltaic conversion process depends on solar irradiation and temperature. Therefore, to maximize the efficiency of the photovoltaic energy system, it is necessary to track the maximum power point of the PV array. The present paper proposes a maximum power point tracker (MPPT) method, based on fuzzy logic controller (FLC), applied to a stand-alone photovoltaic system. It uses a sampling measure of the PV array power and voltage then determines an optimal increment required to have the optimal operating voltage which permits maximum power tracking. This method carries high accuracy around the optimum point when compared to the conventional one. The stand-alone photovoltaic system used in this paper includes two bi-directional DC/DC converters and a lead-acid battery bank to overcome the scare periods. One converter works as an MPP tracker, while the other regulates the batteries state of charge and compensates the power deficit to provide a continuous delivery of energy to the load. The Obtained simulation results show the effectiveness of the proposed fuzzy logic controller.

  11. Optimized Adaptive Perturb and Observe Maximum Power Point Tracking Control for Photovoltaic Generation

    Directory of Open Access Journals (Sweden)

    Luigi Piegari

    2015-04-01

    Full Text Available The power extracted from PV arrays is usually maximized using maximum power point tracking algorithms. One of the most widely used techniques is the perturb & observe algorithm, which periodically perturbs the operating point of the PV array, sometime with an adaptive perturbation step, and compares the PV power before and after the perturbation. This paper analyses the most suitable perturbation step to optimize maximum power point tracking performance and suggests a design criterion to select the parameters of the controller. Using this proposed adaptive step, the MPPT perturb & observe algorithm achieves an excellent dynamic response by adapting the perturbation step to the actual operating conditions of the PV array. The proposed algorithm has been validated and tested in a laboratory using a dual input inductor push-pull converter. This particular converter topology is an efficient interface to boost the low voltage of PV arrays and effectively control the power flow when input or output voltages are variable. The experimental results have proved the superiority of the proposed algorithm in comparison of traditional perturb & observe and incremental conductance techniques.

  12. Analysis of Two Methods to Evaluate Antioxidants

    Science.gov (United States)

    Tomasina, Florencia; Carabio, Claudio; Celano, Laura; Thomson, Leonor

    2012-01-01

    This exercise is intended to introduce undergraduate biochemistry students to the analysis of antioxidants as a biotechnological tool. In addition, some statistical resources will also be used and discussed. Antioxidants play an important metabolic role, preventing oxidative stress-mediated cell and tissue injury. Knowing the antioxidant content…

  13. Two methods to measure granular gas temperature

    Science.gov (United States)

    Chastaing, J.-Y.; Géminard, J.-C.; Naert, A.

    2017-07-01

    Grains are vibrated so as to achieve a granular gas, here regarded as an archetype of a dissipative non equilibrium steady state (NESS). We report on two distinct and concordant experimental measures of the system effective temperature. To do so, a blade fastened to the shaft of a small DC-motor, immersed in the grains, behaves as a driven 1D Brownian rotator, which is used as both actuator and sensor simultaneously. On the one hand, the Gallavotti-Cohen fluctuation theorem, which involves a measure of the asymmetry of the energy exchanges between the rotator and the NESS reservoir, provides a first effective temperature. On the other hand, the fluctuation-dissipation theorem, which involves the relation between the spontaneous fluctuations and the response to a weak perturbation, defines a second, independent, effective temperature. Both methods, even though they are based on drastically different ideas, give nicely concordant results.

  14. Comparison of two methods for customer differentiation

    NARCIS (Netherlands)

    A.F. Gabor (Adriana); Y. Guang (Yang); S. Axsäter (Sven)

    2014-01-01

    textabstractIn response to customer specific time guarantee requirements, service providers can offer differentiated ser- vices. However, conventional customer differentiation methods often lead to high holding costs and may have some practical drawbacks. We compare two customer differentiation

  15. Discrete-Time Dynamical Maximum Power Tracking Control for a Vertical Axis Water Turbine with Retractable Blades

    Directory of Open Access Journals (Sweden)

    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.

  16. Output-Feedback Nonlinear Adaptive Control Strategy of the Single-Phase Grid-Connected Photovoltaic System

    Directory of Open Access Journals (Sweden)

    Abdelmajid Abouloifa

    2018-01-01

    Full Text Available This paper addresses the problem of controlling the single-phase grid connected to the photovoltaic system through a full bridge inverter with LCL-filter. The control aims are threefold: (i imposing the voltage in the output of PV panel to track a reference provided by the MPPT block; (ii regulating the DC-link voltage to guarantee the power exchange between the source and AC grid; (iii ensuring a satisfactory power factor correction (PFC. The problem is dealt with using a cascade nonlinear adaptive controller that is developed making use of sliding-mode technique and observers in order to estimate the state variables and grid parameters, by measuring only the grid current, PV voltage, and the DC bus voltage. The control problem addressed by this work involves several difficulties, including the uncertainty of some parameters of the system and the numerous state variables are inaccessible to measurements. The results are confirmed by simulation under MATLAB∖Simulink∖SimPowerSystems, which show that the proposed regulator is robust with respect to climate changes.

  17. Short-Circuit Fault Tolerant Control of a Wind Turbine Driven Induction Generator Based on Sliding Mode Observers

    Directory of Open Access Journals (Sweden)

    Takwa Sellami

    2017-10-01

    Full Text Available The installed energy production capacity of wind turbines is growing intensely on a global scale, making the reliability of wind turbine subsystems of greater significance. However, many faults like Inter-Turn Short-Circuit (ITSC may affect the turbine generator and quickly lead to a decline in supplied power quality. In this framework, this paper proposes a Sliding Mode Observer (SMO-based Fault Tolerant Control (FTC scheme for Induction Generator (IG-based variable-speed grid-connected wind turbines. First, the dynamic models of the wind turbine subsystems were developed. The control schemes were elaborated based on the Maximum Power Point Tracking (MPPT method and Indirect Rotor Flux Oriented Control (IRFOC method. The grid control was also established by regulating the active and reactive powers. The performance of the wind turbine system and the stability of injected power to the grid were hence analyzed under both healthy and faulty conditions. The robust developed SMO-based Fault Detection and Isolation (FDI scheme was proved to be fast and efficient for ITSC detection and localization.Afterwards, SMO were involved in scheming the FTC technique. Accordingly, simulation results assert the efficacy of the proposed ITSC FTC method for variable-speed wind turbines with faulty IG in protecting the subsystems from damage and ensuring continuous connection of the wind turbine to the grid during ITSC faults, hence maintaining power quality.

  18. A single phase photovoltaic inverter control for grid connected system

    Indian Academy of Sciences (India)

    Melo G and Canesin C A 2013 Evaluation of the main MPPT techniques for photovoltaic applications. IEEE Trans. Ind. Electron. 60(3): 1156–1167. [7] Jain S and Agarwal V 2007 Comparison of the perfor- mance of maximum power point tracking schemes applied to single-stage grid-connected photovoltaic systems.

  19. Reactive Power Control of Single-Stage Three-Phase Photovoltaic System during Grid Faults Using Recurrent Fuzzy Cerebellar Model Articulation Neural Network

    Directory of Open Access Journals (Sweden)

    Faa-Jeng Lin

    2014-01-01

    Full Text Available This study presents a new active and reactive power control scheme for a single-stage three-phase grid-connected photovoltaic (PV system during grid faults. The presented PV system utilizes a single-stage three-phase current-controlled voltage-source inverter to achieve the maximum power point tracking (MPPT control of the PV panel with the function of low voltage ride through (LVRT. Moreover, a formula based on positive sequence voltage for evaluating the percentage of voltage sag is derived to determine the ratio of the injected reactive current to satisfy the LVRT regulations. To reduce the risk of overcurrent during LVRT operation, a current limit is predefined for the injection of reactive current. Furthermore, the control of active and reactive power is designed using a two-dimensional recurrent fuzzy cerebellar model articulation neural network (2D-RFCMANN. In addition, the online learning laws of 2D-RFCMANN are derived according to gradient descent method with varied learning-rate coefficients for network parameters to assure the convergence of the tracking error. Finally, some experimental tests are realized to validate the effectiveness of the proposed control scheme.

  20. Power conversion and control methods for renewable energy sources

    Science.gov (United States)

    Yu, Dachuan

    2005-07-01

    In recent years, there has been an increase in the use of renewable energy due to the growing concern over the pollution caused by fossil-fuel-based energy. Renewable energy sources, such as photovoltaic (PV) and fuel cell, can be used to enhance the safety, reliability, sustainability, and transmission efficiency of a power system. This dissertation focuses on the power conversion and control for two major renewable-energy sources: PV and fuel cell. Firstly, a current-based, maximum power-point tracking (MPPT) algorithm is proposed for PV energy. An economical converter system using the above scheme for converting the output from PV panels into 60 Hz AC voltage is developed and built. Secondly, a novel circuit model for the Proton Exchange Membrane (PEM) fuel-cell stack that is useful in the design and analysis of fuel-cell-based power systems is proposed. This Pspice-based model uses elements available in the Pspice library with some modifications to represent both the static and dynamic responses of a PEM fuel-cell module. The accuracy of the model is verified by comparing the simulation and experimental results. Thirdly, a DSP-controlled three-phase induction-motor drive using constant voltage over frequency is built and can be used in a fuel-cell automobile. A hydrogen sensor is used in the drive to both sound an alarm and shut down the inverter trigger pulses through the DSP. Finally, a hybrid power system consisting of PV panels and fuel cell is proposed and built. In the proposed system, PV panels can supply most of the power when the sunlight is available, and the excess power required by the load is supplied by a fuel cell. Load sharing between a fuel cell (FC) and the PV panel is investigated by both simulation and experiments.

  1. CT perfusion measurements of head and neck carcinoma from single section with largest tumor dimensions or average of multiple sections: Agreement between the two methods and effect on intra- and inter-observer agreement

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, Ahmed M., E-mail: ahm_m_tawfik@hotmail.com [Institut für Diagnostische und Interventionelle Radiologie, Klinikum der J.W.v. Goethe Universität Frankfurt am Main, Theodor-Stern-Kai 7 Frankfurt am Main 60590 (Germany); Diagnostic Radiology Department, Mansoura Faculty of Medicine, 62 Elgomhorya Street, Mansoura 35512 (Egypt); Nour-Eldin, Nour-Eldin A.; Naguib, Nagy N. [Institut für Diagnostische und Interventionelle Radiologie, Klinikum der J.W.v. Goethe Universität Frankfurt am Main, Theodor-Stern-Kai 7 Frankfurt am Main 60590 (Germany); Razek, Ahmed Abdel [Diagnostic Radiology Department, Mansoura Faculty of Medicine, 62 Elgomhorya Street, Mansoura 35512 (Egypt); Denewer, Adel T. [Surgical Oncology Department, Mansoura Oncology Centre, Mansoura Faculty of medicine (Egypt); Bisdas, Sotirios [Department of Neuroradiology, Eberhard Karls University, Tübingen (Germany); Vogl, Thomas J. [Institut für Diagnostische und Interventionelle Radiologie, Klinikum der J.W.v. Goethe Universität Frankfurt am Main, Theodor-Stern-Kai 7 Frankfurt am Main 60590 (Germany)

    2012-10-15

    Purpose: To evaluate the agreement between quantitative CT perfusion measurements of head and neck squamous cell carcinoma (SCC) obtained from single section with maximal tumor dimension and from average values of multiple sections, and to compare intra- and inter-observer agreement of the two methods. Methods: Perfusion was measured for 28 SCC cases using a region of interest (ROI) inserted in the single dynamic CT section showing maximal tumor dimension, then using average values of multiple ROIs inserted in all tumor-containing sections. Agreement between values of blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface area product (PS) calculated by the two methods was assessed. Intra-observer agreement was assessed by comparing repeated calculations done by the same radiologist using both methods after 2 months blinding period. Perfusion measurements were done by another radiologist independently to assess inter-observer agreement of both methods. Results: No significant differences were observed between the means of the 4 perfusion parameters calculated by both methods, all p values >0.05 The 95% limits of agreement between the two methods were (−33.9 to 43) ml/min/100 g for BF, (−2.5 to 2.8) ml/100 g for BV, (−4.9 to 3.9) s for MTT and (−17.5 to 18.6) ml/min/100 g for PS. Narrower limits of agreement were obtained using average of multiple sections than with single section denoting improved intra- and inter-observer agreement. Conclusion: Agreement between both methods is acceptable. Taking the average of multiple sections slightly improves intra- and inter-observer agreement.

  2. Optimal Control to Increase Energy Production of Wind Farm Considering Wake Effect and Lifetime Estimation

    DEFF Research Database (Denmark)

    Tian, Jie; Zhou, Dao; Su, Chi

    2017-01-01

    as an example. Due to the small range of the effective wake area, it is found that the energy production is almost the same. Finally, the pitch angle curve and active power curve are optimized according to the Maximum Energy Production (MEP) of a wind farm. Upon considering and contrasting the MPPT method...... to maximize the energy production of wind farms by considering the wake effect and the lifetime of wind turbine. It starts with the analysis of the pitch angle curve and active power curve seen from the Maximum Power Point Tracking (MPPT) of individual wind turbines. Taking the wake effect into account......, the pitch angle curve and active power curve are optimized with the aim of Maximum Power Generation (MPG) of the wind farm. Afterwards, considering the lifetime of wind turbines, a comparison is offered between the MPPT method and the MPG method for energy production using a simplified two-turbine wind farm...

  3. Dynamic Performance of Maximum Power Point Trackers in TEG Systems Under Rapidly Changing Temperature Conditions

    DEFF Research Database (Denmark)

    Man, E. A.; Sera, D.; Mathe, L.

    2016-01-01

    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...

  4. Simulation of New Simple Fuzzy Logic Maximum Power Point ...

    African Journals Online (AJOL)

    Journal of Fundamental and Applied Sciences ... The input parameters and duty cycle D are used to generate the optimal MPPT under different operating conditions, The photovoltaic system simulated and constructed by photovoltaic arrays, a DC/DC boost converter, a fuzzy MPPT control and a resistive load, The Fuzzy ...

  5. Validation of chimerism in pediatric recipients of allogeneic hematopoietic stem cell transplantation (HSCT) a comparison between two methods: real-time PCR (qPCR) vs. variable number tandem repeats PCR (VNTR PCR).

    Science.gov (United States)

    Kletzel, Morris; Huang, Wei; Olszewski, Marie; Khan, Sana

    2013-01-01

    Post-hematopoietic stem cell transplantation (HSCT) chimerism monitoring is important to assess relapse and therapeutic intervention. The purpose of our study is to compare two methods variable number tandem repeats (VNTR) vs. quantitative real- time polymerase chain reaction (qPCR) in terms of determining chimerism. 127 (peripheral blood n=112, bone marrow n=15) samples were simultaneously tested by VNTR using APO-B, D1S80, D1S111, D17S30, gene loci SRY and ZP3 and qPCR using 34 assays (CA001-CA034) that are designed to a bi-allelic insertion/deletion (indel) polymorphism in the human genome. Samples were separated in three subsets: total WBC, T-cell and Myeloid cells. Extraction of DNA was performed then quantified. We analyzed column statistics, paired t-test and regression analysis for both methods. There was complete correlation between the two methods. The simplicity and rapidity of the test results from the qPCR method is more efficient and accurate to assess chimerism.

  6. State-Space Modeling and Performance Analysis of Variable-Speed Wind Turbine Based on a Model Predictive Control Approach

    Directory of Open Access Journals (Sweden)

    H. Bassi

    2017-04-01

    Full Text Available Advancements in wind energy technologies have led wind turbines from fixed speed to variable speed operation. This paper introduces an innovative version of a variable-speed wind turbine based on a model predictive control (MPC approach. The proposed approach provides maximum power point tracking (MPPT, whose main objective is to capture the maximum wind energy in spite of the variable nature of the wind’s speed. The proposed MPC approach also reduces the constraints of the two main functional parts of the wind turbine: the full load and partial load segments. The pitch angle for full load and the rotating force for the partial load have been fixed concurrently in order to balance power generation as well as to reduce the operations of the pitch angle. A mathematical analysis of the proposed system using state-space approach is introduced. The simulation results using MATLAB/SIMULINK show that the performance of the wind turbine with the MPC approach is improved compared to the traditional PID controller in both low and high wind speeds.

  7. Investigation of the behavior of a three phase grid-connected photovoltaic system to control active and reactive power

    Energy Technology Data Exchange (ETDEWEB)

    Tsengenes, Georgios; Adamidis, Georgios [Department of Electrical Engineering and Computer Engineering, Democritus University of Thrace, University Campus Kimmeria, 67100 Xanthi (Greece)

    2011-01-15

    In this paper, a photovoltaic (PV) system, with maximum power point tracking (MPPT), connected to a three phase grid is presented. The connection of photovoltaic system on the grid takes place in one stage using voltage source inverter (VSI). For a better utilization of the photovoltaic system, the control strategy applied is based on p-q theory. According to this strategy during sunlight the system sends active power to the grid and at the same time compensates the reactive power of the load. In case there is no sunlight (during the night for instance), the inverter only compensates the reactive power of the load. In this paper the use of p-q theory to supply the grid with active power and compensate the reactive power of the load is investigated. The advantage of this control strategy is that the photovoltaic system is operated the whole day. Furthermore, the p-q theory uses simple algebraic calculations without demanding the use of PLL to synchronize the inverter with the grid. (author)

  8. Improvement of Microgrid Dynamic Performance under Fault Circumstances using ANFIS for Fast Varying Solar Radiation and Fuzzy Logic Controller for Wind System

    Directory of Open Access Journals (Sweden)

    Izadbakhsh Maziar

    2014-12-01

    Full Text Available The microgrid (MG technology integrates distributed generations, energy storage elements and loads. In this paper, dynamic performance enhancement of an MG consisting of wind turbine was investigated using permanent magnet synchronous generation (PMSG, photovoltaic (PV, microturbine generation (MTG systems and flywheel under different circumstances. In order to maximize the output of solar arrays, maximum power point tracking (MPPT technique was used by an adaptive neuro-fuzzy inference system (ANFIS; also, control of turbine output power in high speed winds was achieved using pitch angle control technic by fuzzy logic. For tracking the maximum point, the proposed ANFIS was trained by the optimum values. The simulation results showed that the ANFIS controller of grid-connected mode could easily meet the load demand with less fluctuation around the maximum power point. Moreover, pitch angle controller, which was based on fuzzy logic with wind speed and active power as the inputs, could have faster responses, thereby leading to flatter power curves, enhancement of the dynamic performance of wind turbine and prevention of both frazzle and mechanical damages to PMSG. The thorough wind power generation system, PV system, MTG, flywheel and power electronic converter interface were proposed by using Mat-lab/Simulink.

  9. Individual Module Maximum Power Point Tracking for a Thermoelectric Generator Systems

    DEFF Research Database (Denmark)

    Vadstrup, Casper; Chen, Min; Schaltz, Erik

    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....... A converter with an individual MPPT is denoted iMPPT in contrast to the oMPPT which is the denotation of converters which only applies an overall MPPT. In this manuscript a converter capable of handling four TEG-modules are presented and a comparison of the system output power due to an oMPPT and iMPPT...

  10. Optimized Power Dispatch in Wind Farms for Power Maximizing Considering Fatigue Loads

    DEFF Research Database (Denmark)

    Zhang, Baohua; N. Soltani, Mohsen; Hu, Weihao

    2018-01-01

    load of the shafts and the towers within a certain range from the values using traditional strategy, which adopts maximum power point tracking (MPPT) control for each WT. A WT derating control strategy is included in the WT controller and the fatigue load for the tower and shaft is evaluated offline...... at a series of turbulence intensity, mean wind speed and active power reference to form a lookup table, which is used for the WF control. The proposed strategy is compared with WT MPPT control strategy and WF MPPT control strategy. The simulation results show the effectiveness of the proposed strategy....

  11. Modeling, control, and simulation of grid connected intelligent hybrid battery/photovoltaic system using new hybrid fuzzy-neural method.

    Science.gov (United States)

    Rezvani, Alireza; Khalili, Abbas; Mazareie, Alireza; Gandomkar, Majid

    2016-07-01

    Nowadays, photovoltaic (PV) generation is growing increasingly fast as a renewable energy source. Nevertheless, the drawback of the PV system is its dependence on weather conditions. Therefore, battery energy storage (BES) can be considered to assist for a stable and reliable output from PV generation system for loads and improve the dynamic performance of the whole generation system in grid connected mode. In this paper, a novel topology of intelligent hybrid generation systems with PV and BES in a DC-coupled structure is presented. Each photovoltaic cell has a specific point named maximum power point on its operational curve (i.e. current-voltage or power-voltage curve) in which it can generate maximum power. Irradiance and temperature changes affect these operational curves. Therefore, the nonlinear characteristic of maximum power point to environment has caused to development of different maximum power point tracking techniques. In order to capture the maximum power point (MPP), a hybrid fuzzy-neural maximum power point tracking (MPPT) method is applied in the PV system. Obtained results represent the effectiveness and superiority of the proposed method, and the average tracking efficiency of the hybrid fuzzy-neural is incremented by approximately two percentage points in comparison to the conventional methods. It has the advantages of robustness, fast response and good performance. A detailed mathematical model and a control approach of a three-phase grid-connected intelligent hybrid system have been proposed using Matlab/Simulink. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  12. Control and performance analysis of grid connected photovoltaic systems of two different technologies in a desert environment

    Directory of Open Access Journals (Sweden)

    Layachi ZAGHBA

    2017-12-01

    Full Text Available In this study, is to investigate the effect of real climatic conditions on the performance parameters of a 9 kWp grid connected photovoltaic plant during one-year using typical days installed in the desert environment in south of Algeria (Ghardaia site. The PV plant contain the following components: solar PV array, with a DC/DC boost converter, neural MPPT, that allow maximal power conversion into the grid, have been included. These methods can extract maximum power from each of the independent PV arrays connected to DC link voltage level, a DC/AC inverter and a PI current control system. The PV array is divides in two parallel PV technology types; the first includes 100 PV modules mono-crystalline silicon (mc-Si arranged in 20 parallel groups of 5 modules in series, and the second of composed of 24 amorphous modules (Inventux X series, arranged in 6 parallel groups of 4 modules in series. The proposed system tested using MATLAB/SIMULINK platform in which a maximum power tracked under constant and real varying solar irradiance. The study concluded that output power and energy from two PV technology types (mc-Si and Amorphous-Si increases linearly with increase of solar irradiance.

  13. Comparison of H-infinity control and generalized predictive control for a laser scanner system

    DEFF Research Database (Denmark)

    Ordys, A.W.; Stoustrup, Jakob; Smillie, I.

    2000-01-01

    This paper describes tests performed on a laser scanner system to assess the feasibility of H-infinity control and generalized predictive control design techniques in achieving a required performance in a trajectory folowing problem. The two methods are compared with respect to achieved scan time...

  14. Evaluation of two methods of tracings for implants in panoramic radiographs Avaliação de dois métodos de traçados para implantes em radiografias panorâmicas

    Directory of Open Access Journals (Sweden)

    Deborah Queiroz de Freitas

    2004-03-01

    Full Text Available In the last years, computer programs have appeared in order to help dental practitioners in implants planning. These programs aim to facilitate the acquisition of adequate measures in digitalized radiographs. The aims of this study were: to evaluate the intra-examiner agreement in the acquisition of measures using two methods (manual and computer program - Radioimp, comparing their performances. Three examiners analyzed twenty-one panoramic radiographs. They used the two methods in two occasions. In the manual method, the examiners made a tracing on a paper fixed to the images and measured nine regions with a caliper. The images were digitalized and showed in a computer screen to be analyzed in the computer program. The examiners acquired measures of the same regions by the manual method. Vertical measures of spheres in the images were acquired in order to discount the magnifying factor of the technique. Through statistics analysis (p=.05, it was possible to conclude that there were differences in intra-examiner agreement and the examiners had greater difficulty in reproducing the measures when they used the computer program; the measures acquired by the manual method were closer to the real ones.Nos últimos anos, surgiram, na Odontologia, programas de computador para auxiliar o profissional no planejamento de implantes. Esses programas visam facilitar a obtenção de medidas adequadas em exames radiográficos digitalizados. Os objetivos desse trabalho foram: avaliar a concordância intra-examinador na obtenção de medidas por dois métodos (o manual e o com um programa de computador - Radioimp; e comparar o desempenho dos dois métodos. Para isso, 21 radiografias panorâmicas foram analisadas por três avaliadores, pelos dois métodos, em duas ocasiões. No método manual, os avaliadores realizaram um traçado sobre papel acetato fixado às imagens, e, com um paquímetro, obtiveram medidas de nove regiões. Para a análise das imagens no

  15. Impact and appreciation of two methods aiming at reducing hazardous drug environmental contamination: The centralization of the priming of IV tubing in the pharmacy and use of a closed-system transfer device.

    Science.gov (United States)

    Guillemette, Annie; Langlois, Hélène; Voisine, Maxime; Merger, Delphine; Therrien, Roxane; Mercier, Genevieve; Lebel, Denis; Bussières, Jean-François

    2014-12-01

    The main objective was to evaluate the impact of two methods aiming at reducing hazardous drug environmental contamination: the centralization of the priming of IV tubing in the pharmacy and the use of a closed-system transfer device. The secondary objective was to evaluate the satisfaction of pharmacy technicians using a survey. Sites in the hematology-oncology satellite pharmacy and care unit were analyzed for the presence of cyclophosphamide, ifosfamide and methotrexate before and after the centralization of the priming of IV tubing in the pharmacy and before and after using a closed-system transfer device. The limits of detection for cyclophosphamide, ifosfamide and methotrexate were, respectively, of 0.0015 ng/cm(2), 0.0012 ng/cm(2) and 0.0060 ng/cm(2). The pharmacy technician satisfaction was evaluated using a questionnaire. A total of 225 samples was quantified. After the centralization of priming in the pharmacy, no significant difference was found in the proportion of positive samples for cyclophosphamide, ifosfamide and methotrexate. Traces of cyclophosphamide found on the floor in patient care areas was significantly reduced (median[min-max] 0.08[0.06-0.09]ng/cm(2) vs. 0.03[0.02-0.05], p handling difficulties). The centralization of the priming of IV tubing in the pharmacy reduced floor contamination in patient care areas without increasing surface contamination in the pharmacy. Closed-system transfer devices reduced contamination in pharmacy, but handling issues were raised by pharmacy technicians. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  16. SIMULATION OF NEW SIMPLE FUZZY LOGIC MAXIMUM POWER POINT TRACKER FOR PHOTOVOLTAIC ARRAY

    Directory of Open Access Journals (Sweden)

    H. Serhoud

    2015-08-01

    Full Text Available A new simple fuzzy method used for tracking the maximum power point tracker (MPPT for photovoltaic systems is proposed. The input parameters   and duty cycle D are used to generate the optimal MPPT under different operating conditions, The photovoltaic system simulated and constructed by photovoltaic arrays, a DC/DC boost converter, a fuzzy MPPT control and a resistive load, The Fuzzy control law designed and the results in a simulation platform will be presented and compare to Perturbation and observation (P&O controller.

  17. Assessing dose–response effects of national essential medicine policy in China: comparison of two methods for handling data with a stepped wedge-like design and hierarchical structure

    Science.gov (United States)

    Ren, Yan; Yang, Min; Li, Qian; Pan, Jay; Chen, Fei; Li, Xiaosong; Meng, Qun

    2017-01-01

    Objectives To introduce multilevel repeated measures (RM) models and compare them with multilevel difference-in-differences (DID) models in assessing the linear relationship between the length of the policy intervention period and healthcare outcomes (dose–response effect) for data from a stepped-wedge design with a hierarchical structure. Design The implementation of national essential medicine policy (NEMP) in China was a stepped-wedge-like design of five time points with a hierarchical structure. Using one key healthcare outcome from the national NEMP surveillance data as an example, we illustrate how a series of multilevel DID models and one multilevel RM model can be fitted to answer some research questions on policy effects. Setting Routinely and annually collected national data on China from 2008 to 2012. Participants 34 506 primary healthcare facilities in 2675 counties of 31 provinces. Outcome measures Agreement and differences in estimates of dose–response effect and variation in such effect between the two methods on the logarithm-transformed total number of outpatient visits per facility per year (LG-OPV). Results The estimated dose–response effect was approximately 0.015 according to four multilevel DID models and precisely 0.012 from one multilevel RM model. Both types of model estimated an increase in LG-OPV by 2.55 times from 2009 to 2012, but 2–4.3 times larger SEs of those estimates were found by the multilevel DID models. Similar estimates of mean effects of covariates and random effects of the average LG-OPV among all levels in the example dataset were obtained by both types of model. Significant variances in the dose–response among provinces, counties and facilities were estimated, and the ‘lowest’ or ‘highest’ units by their dose–response effects were pinpointed only by the multilevel RM model. Conclusions For examining dose–response effect based on data from multiple time points with hierarchical structure and the

  18. Assessing dose-response effects of national essential medicine policy in China: comparison of two methods for handling data with a stepped wedge-like design and hierarchical structure.

    Science.gov (United States)

    Ren, Yan; Yang, Min; Li, Qian; Pan, Jay; Chen, Fei; Li, Xiaosong; Meng, Qun

    2017-02-22

    To introduce multilevel repeated measures (RM) models and compare them with multilevel difference-in-differences (DID) models in assessing the linear relationship between the length of the policy intervention period and healthcare outcomes (dose-response effect) for data from a stepped-wedge design with a hierarchical structure. The implementation of national essential medicine policy (NEMP) in China was a stepped-wedge-like design of five time points with a hierarchical structure. Using one key healthcare outcome from the national NEMP surveillance data as an example, we illustrate how a series of multilevel DID models and one multilevel RM model can be fitted to answer some research questions on policy effects. Routinely and annually collected national data on China from 2008 to 2012. 34 506 primary healthcare facilities in 2675 counties of 31 provinces. Agreement and differences in estimates of dose-response effect and variation in such effect between the two methods on the logarithm-transformed total number of outpatient visits per facility per year (LG-OPV). The estimated dose-response effect was approximately 0.015 according to four multilevel DID models and precisely 0.012 from one multilevel RM model. Both types of model estimated an increase in LG-OPV by 2.55 times from 2009 to 2012, but 2-4.3 times larger SEs of those estimates were found by the multilevel DID models. Similar estimates of mean effects of covariates and random effects of the average LG-OPV among all levels in the example dataset were obtained by both types of model. Significant variances in the dose-response among provinces, counties and facilities were estimated, and the 'lowest' or 'highest' units by their dose-response effects were pinpointed only by the multilevel RM model. For examining dose-response effect based on data from multiple time points with hierarchical structure and the stepped wedge-like designs, multilevel RM models are more efficient, convenient and informative than

  19. Patrones dietarios en adolescentes mexicanas. Una comparación de dos métodos. Encuesta Nacional de Nutrición, 1999 Dietary patterns in Mexican adolescent girls. A comparison of two methods. National Nutrition Survey, 1999

    Directory of Open Access Journals (Sweden)

    Ana Lilia Lozada

    2007-08-01

    predominated in the [R] pattern (48% and 6% of total energy, respectively. In the [W] pattern, wheat products and meat contributed 19% and 10.6% of energy, respectively. Moreover, four dietary patterns were identified through factor analysis. Factor 1 had a positive loading factor on wheat products, desserts, and meat. Factor 2 was characterized by a high consumption of low-fat dairy and low-fiber breakfast cereals. Factor 3 had a high loading for sweetened beverages and industrialized foods. Factor 4 had a moderate loading on maize products and legumes. CONCLUSION: We identified dietary patterns in Mexican adolescent girls by two methods, obtaining comparable results between methods.

  20. Droop assignment algorithm for the inertial control of a DFIG-based wind power plant for supporting the grid frequency

    DEFF Research Database (Denmark)

    Lee, Jinsik; Kang, Yong Cheol; Muljadi, Edward

    2014-01-01

    In a wind power plant (WPP) consisting of multiple wind generators (WGs), the wind speed of WGs at the downstream side decreases due to the wake effect, and thus their rotor speeds are smaller than those of the upstream WGs because of an MPPT operation. Therefore, WGs in a WPP have different amou...

  1. Benchmarking Advanced Control Algorithms for a Laser Scanner System

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Ordys, A.W.; Smillie, I.

    1996-01-01

    The paper describes tests performed on the laser scanner system toassess feasibility of modern control techniques in achieving a requiredperformance in the trajectory following problem. The two methods tested areQTR H-infinity and Predictive Control. The results are ilustated ona simulation example....

  2. Modeling and control of hybrid wind/photovoltaic/fuel cell distributed generation systems

    Science.gov (United States)

    Wang, Caisheng

    Due to ever increasing energy consumption, rising public awareness of environmental protection, and steady progress in power deregulation, alternative (i.e., renewable and fuel cell based) distributed generation (DG) systems have attracted increased interest. Wind and photovoltaic (PV) power generation are two of the most promising renewable energy technologies. Fuel cell (FC) systems also show great potential in DG applications of the future due to their fast technology development and many merits they have, such as high efficiency, zero or low emission (of pollutant gases) and flexible modular structure. The modeling and control of a hybrid wind/PV/FC DG system is addressed in this dissertation. Different energy sources in the system are integrated through an AC bus. Dynamic models for the main system components, namely, wind energy conversion system (WECS), PV energy conversion system (PVECS), fuel cell, electrolyzer, power electronic interfacing circuits, battery, hydrogen storage tank, gas compressor and gas pressure regulator, are developed. Two types of fuel cells have been modeled in this dissertation: proton exchange membrane fuel cell (PEMFC) and solid oxide fuel cell (SOFC). Power control of a grid-connected FC system as well as load mitigation control of a stand-alone FC system are investigated. The pitch angle control for WECS, the maximum power point tracking (MPPT) control for PVECS, and the control for electrolyzer and power electronic devices, are also addressed in the dissertation. Based on the dynamic component models, a simulation model for the proposed hybrid energy system has been developed using MATLAB/Simulink. The overall power management strategy for coordinating the power flows among the different energy sources is presented in the dissertation. Simulation studies have been carried out to verify the system performance under different scenarios using a practical load profile and real weather data. The results show that the overall power

  3. Comparative study of patient doses calculated with two methods for breast digital tomosynthesis; Estudio de los valores de dosis a pacientes en examenes de tomosintesis de mama estimados con dos metodos distintos

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, M.; Chevalier, M.; Calzado, A.; Garayo, J.; Valverde, J.

    2015-07-01

    In this study, the average glandular doses (DG) delivered in breast tomosynthesis examinations were estimated over a sample of 150 patients using two different methods. In method 1, the conversion factors air-kerma to DG used were those tabulated by Dance et al. and in method 2 were the ones from Feng et al. The protocol for the examination followed in the unit of this study consists in two views per breast, each view composed by a 2D acquisition and a tomosynthesis scan (3D). The resulting DG values from both methods present statistically significant differences (p=0.02) for the 2D modality and were similar for the 3D scan (p=0.22). The estimated median value of DG for the most frequent breasts (thicknesses between 50 and 60 mm) delivered in a single 3D acquisition is 1.7 mGy (36% and 17% higher than the value for the 2D mode estimated with each method) which lies far below the tolerances established by the Spanish Protocol Quality Control in Radiodiagnostic (2011). The total DG for a tomosynthesis examination (6.0 mGy) is a factor 2.4 higher than the dose delivered in a 2D examination with two views (method 1). (Author)

  4. Achieving Maximum Power from Thermoelectric Generators with Maximum-Power-Point-Tracking Circuits Composed of a Boost-Cascaded-with-Buck Converter

    Science.gov (United States)

    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.

  5. A Micro-scale Wind Turbine Fed BLDC Motor for Electric Vehicle Drive Application

    OpenAIRE

    Kazraji, Saeed Masoumi; Khanabdal, Saheb; Soflaye, Ramin Bavil; Sabahi, Mehran

    2016-01-01

    In this paper a permanent magnet brushless dc motor (PMBLDCM) based driver with a wind-generator (WG) in maximum power point tracking (MPPT) condition is proposed. The proposed system has a high efficiency buck-type dc/dc converter and control unit running the MPPT function. The WG optimal power characteristic and wind speed measuring data are not required while the WG works in variable speed mode, therefore higher reliability, simplicity, lower cost and less mechanical Tension of the WG are ...

  6. Maximum power point tracking converter based on the open-circuit voltage method for thermoelectric generators

    OpenAIRE

    Montecucco, Andrea; Knox, Andrew

    2015-01-01

    Thermoelectric generators (TEGs) convert heat energy into electricity in a quantity dependant on the temperature difference across them and the electrical load applied. It is critical to track the optimum electrical operating point through the use of power electronic converters controlled by a Maximum Power Point Tracking (MPPT) algorithm. The MPPT method based on the opencircuit voltage is arguably the most suitable for the linear electrical characteristic of TEGs. This paper presents an inn...

  7. Hybrid centralized-distributed power conditioning system for thermoelectric generator with high energy efficiency

    DEFF Research Database (Denmark)

    Wu, Hongfei; Sun, Kai; Chen, Min

    2013-01-01

    The unbalanced temperature distribution influences the power output of thermoelectric generator (TEG) system, which leads to mismatch power among TEG modules. This mismatch power degrades the energy efficiency of TEG systems based on the series-connected TEG modules. A hybrid centralized...... the proposed system, which benefits for implementing high MPPT efficiency and high conversion efficiency simultaneously. A hybrid MPPT control strategy is proposed for this HCD power conditioning system. The characteristics, circuit implementation and operation principles of the proposed system are presented...

  8. Evaluation of a photovoltaic energy mechatronics system with a built-in quadratic maximum power point tracking algorithm

    Energy Technology Data Exchange (ETDEWEB)

    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)

  9. Maximum power point tracking for photovoltaic solar pump based on ANFIS tuning system

    Directory of Open Access Journals (Sweden)

    S. Shabaan

    2018-05-01

    Full Text Available Solar photovoltaic (PV systems are a clean and naturally replenished energy source. PV panels have a unique point which represents the maximum available power and this point depend on the environmental conditions such as temperature and irradiance. A maximum power point tracking (MPPT is therefore necessary for maximum efficiency. In this paper, a study of MPPT for PV water pumping system based on adaptive neuro-fuzzy inference system (ANFIS is discussed. A comparison between the performance of the system with and without MPPT is carried out under varying irradiation and temperature conditions. ANFIS based controller shows fast response with high efficiency at all irradiance and temperature levels making it a powerful technique for non-linear systems as PV modules. Keywords: MPPT, ANFIS, Boost converter, PMDC pump

  10. Control rod control device

    International Nuclear Information System (INIS)

    Seiji, Takehiko; Obara, Kohei; Yanagihashi, Kazumi

    1998-01-01

    The present invention provides a device suitable for switching of electric motors for driving each of control rods in a nuclear reactor. Namely, in a control rod controlling device, a plurality of previously allotted electric motors connected in parallel as groups, and electric motors of any selected group are driven. In this case, a voltage of not driving predetermined selected electric motors is at first applied. In this state an electric current supplied to the circuit of predetermined electric motors is detected. Whether integration or failure of a power source and the circuit of the predetermined electric motors are normal or not is judged by the detected electric current supplied. After they are judged normal, the electric motors are driven by a regular voltage. With such procedures, whether the selected circuit is normal or not can be accurately confirmed previously. Since the electric motors are not driven just at the selected time, the control rods are not operated erroneously. (I.S.)

  11. Real-time Modelling, Diagnostics and Optimised MPPT for Residential PV Systems

    DEFF Research Database (Denmark)

    Sera, Dezso

    and generic nature, and has the benefit of also being efficient in fast-changing conditions. Furthermore, the algorithm has been successfully implemented on a commercial PV inverter, currently on the market. In Chapter 3, an overview of the existing mathematical models used to describe the electrical...... responsible for yield-reduction of residential photovoltaic systems. Combining the model calculations with measurements, a method to detect changes in the panels’ series resistance based on the slope of the I − V curve in the vicinity of open-circuit conditions and scaled to Standard Test Conditions (STC......) , is proposed. The results confirm the benefits of the proposed method in terms of robustness to irradiance changes and to partial shadows. In order to detect partial shadows on PV panels, a method based on equivalent thermal voltage (Vt) monitoring is proposed. Vt is calculated using the simplified three...

  12. A Simple and Efficient MPPT Method for Low-Power PV Cells

    Directory of Open Access Journals (Sweden)

    Maria Teresa Penella

    2014-01-01

    Full Text Available Small-size PV cells have been used to power sensor nodes. These devices present limited computing resources and so low complexity methods have been used in order to extract the maximum power from the PV cells. Among them, the fractional open circuit voltage (FOCV method has been widely proposed, where the maximum power point of the PV cell is estimated from a fraction of its open circuit voltage. Here, we show a generalization of the FOCV method that keeps its inherent simplicity and improves the tracking efficiency. First, a single-diode model for PV cells was used to compute the tracking efficiency versus irradiance. Computations were carried out for different values of the parameters involved in the PV cell model. The proposed approach clearly outperformed the FOCV method, specially at low irradiance, which is significant for powering sensor nodes. Experimental tests performed with a 500 mW PV panel agreed with these results.

  13. A simple and efficient MPPT method for low-power PV cells

    OpenAIRE

    Penella López, María Teresa; Gasulla Forner, Manuel

    2014-01-01

    Small-size PV cells have been used to power sensor nodes. These devices present limited computing resources and so low complexity methods have been used in order to extract the maximum power from the PV cells. Among them, the fractional open circuit voltage (FOCV) method has been widely proposed, where the maximum power point of the PV cell is estimated from a fraction of its open circuit voltage. Here, we show a generalization of the FOCV method that keeps its inherent simplicity and improve...

  14. Modeling and Simulation of PV Array and its Performance Enhancement Using MPPT (P&O) Technique

    OpenAIRE

    T.Chaitanya; J.Surya Kumari; Ch.Saibabu

    2011-01-01

    The renewable energy will be an increasingly important part of power generation in the new millennium. Photovoltaic (PV) systems produce DC electricity when sunlight shines on the PV array, requiring little maintenance, and emitting no noise, among others. Day-by –day the energy demand is increasing and thus the need for a renewable source that will not harm the environment are of prime importance. The proposed model uses basic circuit equation of the photovoltaic solar cells including the ef...

  15. Conception d'un convertisseur MPPT pour Optmiser le fonctionnement d'un Generateur photovoltaique.

    OpenAIRE

    RACHEDI, MERWAN

    2014-01-01

    La production d'energie électrique à l'aide de panneaux photovoltaiques présente un point optimum de fonctionnement , cest à dire qu'il existe une tension aux bornes du générateur pour laquelle la puissance recueillie est maximale.

  16. MODEL PREDICTIVE CONTROL FOR PHOTOVOLTAIC STATION MAXIMUM POWER POINT TRACKING SYSTEM

    Directory of Open Access Journals (Sweden)

    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.

  17. Control and Modulation Techniques for a Centralized PV Generation System Grid Connected via an Interleaved Inverter

    Directory of Open Access Journals (Sweden)

    Gianluca Brando

    2016-09-01

    Full Text Available In the context of grid connected photovoitaic (PV generation systems, there are two paramount aspects regarding the Maximum Power Point Tracking (MPPT of the photovoltaic units and the continuity of the service. The most diffused MPPT algorithms are based on either perturb and observe, or on an incremental conductance approach and need both PV current and voltage measurements. Several topology reconfigurable converters are also associated with the PV plants, guaranteeing fault-tolerant features. The generation continuity can also be assured by interleaved inverters, which keep the system operating at reduced maximum power in case of failure. In this paper, an evolution of a hysteresis based MPPT algorithm is presented, based on the measurement of only one voltage, together with a novel space vector modulation suitable for a two-channel three-phase grid connected interleaved inverter. The proposed MMPT algorithm and modulation technique are tested by means of several numerical analyses on a PV generation system of about 200 kW maximum power. The results testify the validity of the proposed strategies, showing good performance, even during a fault occurrence and in the presence of deep shading conditions.

  18. Comparative analysis of perturb & observe and fuzzy logic maximum power point tracking techniques for a photovoltaic array under partial shading conditions

    Directory of Open Access Journals (Sweden)

    T. MURALI MOHAN

    2015-12-01

    Full Text Available The interfacing of maximum power point tracking (MPPT controller is more concern as it contributes significantly to the power output of photovoltaic systems. The perturb and observe (P&O and fuzzy logic based P&O are two most promising MPPT techniques in wide range of irradiance conditions which include fully shaded condition to no shading, uniform and non uniform shadings among the strings. This paper analyzes the implementation of those two MPPT techniques to a photovoltaic (PV array in MATLAB/SIMULINK environment. Basically the power verses voltage curve of a PV array is highly non linear which contains single peak in the curve under uniform irradiance but the non uniform irradiance leaves multiple peaks in the curve. The MPPT normally controls the boost converter duty cycle to track the global peak power point of the PV array. When multiple peaks are present, the P&O has the probability of capturing a local maximum point rather than a global maximum. It is observed that under normal shadings both MPPTs are performed well but under partial shadings Fuzzy logic based P&O MPPT outperform over P&O MPPT.

  19. Optimisation of underwater visual census and controlled angling ...

    African Journals Online (AJOL)

    Whereas UVC provided less variable estimates of relative density, controlled angling provided greater sampling efficiency. It is thus recommended that the two methods be used in conjunction. The optimal sampling protocols identified are suitable for rapid assessments or long-term monitoring of subtidal, temperate reef fish ...

  20. Measuring populism: comparing two methods of content analysis

    NARCIS (Netherlands)

    Rooduijn, M.; Pauwels, T.

    2011-01-01

    The measurement of populism - particularly over time and space - has received only scarce attention. In this research note two different ways to measure populism are compared: a classical content analysis and a computer-based content analysis. An analysis of political parties in the United Kingdom,

  1. Two methods of space--time energy densification

    International Nuclear Information System (INIS)

    Sahlin, R.L.

    1976-01-01

    With a view to the goal of net energy production from a DT microexplosion, we study two ideas (methods) through which (separately or in combination) energy may be ''concentrated'' into a small volume and short period of time--the so-called space-time energy densification or compression. We first discuss the advantages and disadvantages of lasers and relativistic electron-beam (E-beam) machines as the sources of such energy and identify the amplification of laser pulses as a key factor in energy compression. The pulse length of present relativistic E-beam machines is the most serious limitation of this pulsed-power source. The first energy-compression idea we discuss is the reasonably efficient production of short-duration, high-current relativistic electron pulses by the self interruption and restrike of a current in a plasma pinch due to the rapid onset of strong turbulence. A 1-MJ plasma focus based on this method is nearing completion at this Laboratory. The second energy-compression idea is based on laser-pulse production through the parametric amplification of a self-similar or solitary wave pulse, for which analogs can be found in other wave processes. Specifically, the second energy-compression idea is a proposal for parametric amplification of a solitary, transverse magnetic pulse in a coaxial cavity with a Bennett dielectric rod as an inner coax. Amplifiers of this type can be driven by the pulsed power from a relativistic E-beam machine. If the end of the inner dielectric coax is made of LiDT or another fusionable material, the amplified pulse can directly drive a fusion reaction--there would be no need to switch the pulse out of the system toward a remote target

  2. The Comparison of learning radiographic extraoral landmarks through two methods

    Directory of Open Access Journals (Sweden)

    Tahmineh Razi

    2017-01-01

    Full Text Available Objectives: The long time interval between teaching anatomy courses to students and the courses on extraoral radiographs results in forgetting the location of radiographic anatomic landmarks without any retention; therefore, it is necessary to use other educational techniques due to short duration of educational courses. To this end, the present study was undertaken to evaluate the effect of a combination of lectures and computer techniques on teaching extraoral radiographs to undergraduate dental students. Methods: In the present interventional study, dental students entering the university in the same year (referred to as one class were divided into two groups; one group received conventional teaching and one group received combinational teaching technique. Students entering the next year were taught using the same teaching techniques. The results were compared between groups and classes. Results: Comparison of the results of the first test between the two classes showed significant differences between the two groups (P<0.001. Comparison of the results of the second test between the two classes revealed no significant differences in the conventional method (P=0.76; however, the combination technique exhibited significant differences (P=0.006. In the first test, comparison of the two techniques in the students entering the university in 2006 showed no significant differences (P=0.055; however, students entering the university in 2007 exhibited significant differences (P=0.03. In the second test, comparison of the two techniques in both classes revealed significant differences (P<0.001. Conclusion: If more time is allocated to the combination technique, learning improves even in a short time. This method can replace the conventional method to teach interpretation of extraoral radiographs after evaluation of academic level of the studies.

  3. Comparison of Two Methods for the Routine Extraction and ...

    African Journals Online (AJOL)

    Whereas the enzymatic test proved highly reliable for free glucose, it was not useful for the analysis of glucose derived after hydrolysis of starch with perchloric acid. For starch analysis, the iodine/iodide colour reaction was found to be acceptable. Taking the limitation of the anthrone method into account, it was found the ...

  4. TWO METHODS FOR REMOTE ESTIMATION OF COMPLETE URBAN SURFACE TEMPERATURE

    Directory of Open Access Journals (Sweden)

    L. Jiang

    2017-09-01

    Full Text Available Complete urban surface temperature (TC is a key parameter for evaluating the energy exchange between the urban surface and atmosphere. At the present stage, the estimation of TC still needs detailed 3D structure information of the urban surface, however, it is often difficult to obtain the geometric structure and composition of the corresponding temperature of urban surface, so that there is still lack of concise and efficient method for estimating the TC by remote sensing. Based on the four typical urban surface scale models, combined with the Envi-met model, thermal radiant directionality forward modeling and kernel model, we analyzed a complete day and night cycle hourly component temperature and radiation temperature in each direction of two seasons of summer and winter, and calculated hemispherical integral temperature and TC. The conclusion is obtained by examining the relationship of directional radiation temperature, hemispherical integral temperature and TC: (1 There is an optimal angle of radiation temperature approaching the TC in a single observation direction when viewing zenith angle is 45–60°, the viewing azimuth near the vertical surface of the sun main plane, the average absolute difference is about 1.1 K in the daytime. (2 There are several (3–5 times directional temperatures of different view angle, under the situation of using the thermal radiation directionality kernel model can more accurately calculate the hemispherical integral temperature close to TC, the mean absolute error is about 1.0 K in the daytime. This study proposed simple and effective strategies for estimating TC by remote sensing, which are expected to improve the quantitative level of remote sensing of urban thermal environment.

  5. Comparison of two methods forecasting binding rate of plasma protein.

    Science.gov (United States)

    Hongjiu, Liu; Yanrong, Hu

    2014-01-01

    By introducing the descriptors calculated from the molecular structure, the binding rates of plasma protein (BRPP) with seventy diverse drugs are modeled by a quantitative structure-activity relationship (QSAR) technique. Two algorithms, heuristic algorithm (HA) and support vector machine (SVM), are used to establish linear and nonlinear models to forecast BRPP. Empirical analysis shows that there are good performances for HA and SVM with cross-validation correlation coefficients Rcv(2) of 0.80 and 0.83. Comparing HA with SVM, it was found that SVM has more stability and more robustness to forecast BRPP.

  6. A psychophysical comparison of two methods for adaptive histogram equalization.

    Science.gov (United States)

    Zimmerman, J B; Cousins, S B; Hartzell, K M; Frisse, M E; Kahn, M G

    1989-05-01

    Adaptive histogram equalization (AHE) is a method for adaptive contrast enhancement of digital images. It is an automatic, reproducible method for the simultaneous viewing of contrast within a digital image with a large dynamic range. Recent experiments have shown that in specific cases, there is no significant difference in the ability of AHE and linear intensity windowing to display gray-scale contrast. More recently, a variant of AHE which limits the allowed contrast enhancement of the image has been proposed. This contrast-limited adaptive histogram equalization (CLAHE) produces images in which the noise content of an image is not excessively enhanced, but in which sufficient contrast is provided for the visualization of structures within the image. Images processed with CLAHE have a more natural appearance and facilitate the comparison of different areas of an image. However, the reduced contrast enhancement of CLAHE may hinder the ability of an observer to detect the presence of some significant gray-scale contrast. In this report, a psychophysical observer experiment was performed to determine if there is a significant difference in the ability of AHE and CLAHE to depict gray-scale contrast. Observers were presented with computed tomography (CT) images of the chest processed with AHE and CLAHE. Subtle artificial lesions were introduced into some images. The observers were asked to rate their confidence regarding the presence of the lesions; this rating-scale data was analyzed using receiver operating characteristic (ROC) curve techniques. These ROC curves were compared for significant differences in the observers' performances. In this report, no difference was found in the abilities of AHE and CLAHE to depict contrast information.

  7. Test of two methods for determining herbaceous yield and botanical ...

    African Journals Online (AJOL)

    Above-ground herbaceous yield was estimated using the comparative yield method to win + 10% (p < 0,05) of the harvested mean using 150 harvested and 600 rated quadrats of 50 x 50 cm. The number of quadrats can be substantially reduced by improved observer rating. Using the dry mass rank method and 240 ...

  8. Two Methods for Antialiased Wireframe Drawing with Hidden Line Removal

    DEFF Research Database (Denmark)

    Bærentzen, Jakob Andreas; Munk-Lund, Steen; Gjøl, Mikkel

    2008-01-01

    Two novel and robust techniques for wireframe drawing are proposed. Neither suffer from the well-known artifacts associated with the standard two pass, offset based techniques for wireframe drawing. Both methods draw prefiltered lines and produce high-quality antialiased results without super...

  9. Comparison between two methods to measure microalbuminuria: immunonephelemetry and radioimmunology

    International Nuclear Information System (INIS)

    Dezier, J.F.; Le Reun, M.; Poirier, J.Y.; Jouanolle, A.M.

    1987-01-01

    The early detection of microalbuminuria in insulin dependent diabetes is considered as a sign of initial stage of initial stage of nephropathy (possibly reversible if glycemic balance is well maintained). This detection requires very accurate methods as radioimmuoassays. Yet, they are so slow that they represent an obstacle to systematic detection. We report an appraisement of an immunonephelemetric method. Results reveal that immunonephelemetry is a sensitive and accurate method (threshold of sensitivity 0,5 mg/l; CV intra assay [fr

  10. Comparison between two methods to measure microalbuminuria: immunonephelemetry and radioimmunology

    Energy Technology Data Exchange (ETDEWEB)

    Dezier, J.F.; Le Reun, M.; Poirier, J.Y.; Jouanolle, A.M.

    1987-01-01

    The early detection of microalbuminuria in insulin dependent diabetes is considered as a sign of initial stage of initial stage of nephropathy (possibly reversible if glycemic balance is well maintained). This detection requires very accurate methods as radioimmuoassays. Yet, they are so slow that they represent an obstacle to systematic detection. We report an appraisement of an immunonephelemetric method. Results reveal that immunonephelemetry is a sensitive and accurate method (threshold of sensitivity 0,5 mg/l; CV intra assay < 5%; CV inter assays < 10%; analytical recovery: 94-104%). Moreover, immunonephelemetry and radioimmulonogy are significantly well correlated (r = 0,977, p < 0,001). As a conclusion, we can say that thanks to complete automation, immunoephelemetry is a choice method to test great lines of samples.

  11. TWO METHODS FOR SELF CALIBRATION OF DIGITAL CAMERA

    Directory of Open Access Journals (Sweden)

    A. Sampath

    2012-07-01

    Full Text Available Photogrammetric mapping using Commercial of the Shelf (COTS cameras is becoming more popular. Their popularity is augmented by the increasing use of Unmanned Aerial Vehicles (UAV as a platform for mapping. The mapping precision of these methods can be increased by using a calibrated camera. The USGS/EROS has developed an inexpensive, easy to use method, particularly for calibrating short focal length cameras. The method builds on a self-calibration procedure developed for the USGS EROS Data Center by Pictometry (and augmented by Dr. C.S Fraser, that uses a series of coded targets. These coded targets form different patterns that are imaged from nine different locations with differing camera orientations. A free network solution using collinearity equations is used to determine the calibration parameters. For the smaller focal length COTS cameras, the USGS has developed a procedure that uses a small prototype box that contains these coded targets. The design of the box is discussed, along with best practices for calibration procedure. Results of calibration parameters obtained using the box are compared with the parameters obtained using more established standard procedures.

  12. Two Methods for Remote Estimation of Complete Urban Surface Temperature

    Science.gov (United States)

    Jiang, L.; Zhan, W.; Zou, Z.

    2017-09-01

    Complete urban surface temperature (TC) is a key parameter for evaluating the energy exchange between the urban surface and atmosphere. At the present stage, the estimation of TC still needs detailed 3D structure information of the urban surface, however, it is often difficult to obtain the geometric structure and composition of the corresponding temperature of urban surface, so that there is still lack of concise and efficient method for estimating the TC by remote sensing. Based on the four typical urban surface scale models, combined with the Envi-met model, thermal radiant directionality forward modeling and kernel model, we analyzed a complete day and night cycle hourly component temperature and radiation temperature in each direction of two seasons of summer and winter, and calculated hemispherical integral temperature and TC. The conclusion is obtained by examining the relationship of directional radiation temperature, hemispherical integral temperature and TC: (1) There is an optimal angle of radiation temperature approaching the TC in a single observation direction when viewing zenith angle is 45-60°, the viewing azimuth near the vertical surface of the sun main plane, the average absolute difference is about 1.1 K in the daytime. (2) There are several (3-5 times) directional temperatures of different view angle, under the situation of using the thermal radiation directionality kernel model can more accurately calculate the hemispherical integral temperature close to TC, the mean absolute error is about 1.0 K in the daytime. This study proposed simple and effective strategies for estimating TC by remote sensing, which are expected to improve the quantitative level of remote sensing of urban thermal environment.

  13. Early results of two methods of posterior spinal stabilization in ...

    African Journals Online (AJOL)

    2013-04-17

    Apr 17, 2013 ... Discussion. PSR has become the gold standard in posterior spinal fusion techniques. Its success has revolutionized spinal surgery. The Advantages include three column fusion as against one column fusion as is seen in other posterior fusion techniques like Rogers and Bohlman's techniques.[9‑13] Other.

  14. Elution Profiles of Two Methods of Antibiotic Tibial Nail Preparations.

    Science.gov (United States)

    Karek, Matthew R; Jackson, Nancy M; Flynn, Jeffrey C; Vaidya, Rahul; Markel, David C

    2017-05-01

    Interlocking nails coated with antibiotic-supplemented cement provide effective treatment of infected long bone nonunion, but the thicker coating on guidewires may provide greater antibacterial activity. This study compared the properties of cement cured on each construct by evaluating 2-cm segments of 8-mm interlocking nails and 3.5-mm guidewires coated with antibiotic-supplemented cement. Each construct (n=7 for each group) was coated with polymethylmethacrylate cement (Simplex; Stryker Orthopaedics, Mahwah, New Jersey) containing either 1 g tobramycin or 1 g vancomycin powder plus 2.2 g tobramycin powder. A No. 40 French polyvinyl chloride chest tube was used as a mold for all constructs. Segments were soaked in sterile phosphate-buffered saline, and entire aliquots were exchanged at various intervals over a 6-week period. Antibiotic concentration, antibacterial activity, cement curing temperature, and porosity were measured. At least half of the total elution of antibiotics occurred within the first 24 hours for all constructs. For the tobramycin-only cement, no differences between constructs were observed. For constructs containing both antibiotics, interlocking nails showed more antibiotic release than guidewires at most time points (PAntibiotics were released for 6 weeks and continued to inhibit Staphylococcus aureus growth. Cement curing temperatures for interlocking nails were lower than those for guidewires (Pantibiotic released did not directly relate to porosity for any construct type. Interlocking nails coated with antibiotic-supplemented cement may provide greater antibiotic delivery to infected long bone nonunion compared with guidewires. A thin mantle of cement may allow greater elution, possibly as a result of cooler exothermic reactions. [Orthopedics. 2017; 40(3):e436-e442.]. Copyright 2017, SLACK Incorporated.

  15. Factor analyses of a social support scale using two methods.

    Science.gov (United States)

    Yu, Yu; Shiu, Cheng-Shi; Yang, Joyce P; Wang, Mingjiong; Simoni, Jane M; Chen, Wei-ti; Cheng, Joy; Zhao, Hongxin

    2015-04-01

    Evaluation and comparison of the factor structure of the Medical Outcomes Study Social Support Survey (MOS-SSS) using both confirmatory factor analysis (CFA) and exploratory factor analysis (EFA) with two samples of people living with HIV/AIDS in China. Secondary analyses were conducted with data from two comparable samples of 320 people living with HIV/AIDS from the same hospital using the same inclusion criteria. The first sample of 120 was collected in 2006, and the second sample of 200 was collected in 2012. For each sample, CFA was first performed on the original four-factor structure to check model fit, followed by EFA to explore other factor structures and a subsequent CFA for model fit statistics to be compared to the original four-factor CFA. In both samples, CFA on the originally hypothesized four-factor structure yielded an acceptable model fit. The EFA yielded a two-factor solution in both samples, with different items included in each factor for the two samples. Comparison of CFA on the a priori four-factor structure and the new two-factor structure in both samples indicated that both factor structures were of acceptable model fit, with the four-factor model performing slightly better than the two-factor model. Factor structure of the MOS-SSS is method-dependent, with CFA supporting a four-factor structure, while EFA yielded a two-factor structure in two separate samples. We need to be careful in selecting the analytic method when applying the MOS-SSS to various samples and choose the factor structure that best fits the theoretical model.

  16. RADIATION DEGRADATION OF PCBS IN SEDIMENTS: COMPARISON OF TWO METHODS

    Directory of Open Access Journals (Sweden)

    Ľubica Darážová

    2016-12-01

    Full Text Available Polychlorinated biphenyls are toxic compounds which have accumulated in river sediments in Eastern Slovakia. Bioaccumulation could cause even cancer. Radiation degradation with electrons is new and perspective method to dechlorinate PCBs in sediment matrix. We tested the influence of two difference chemical pretreatments and electron irradiation on PCB contaminated sediments.

  17. Early results of two methods of posterior spinal stabilization in ...

    African Journals Online (AJOL)

    , surgical site infection (P ≥ 0.416), neurological deficits (P ≥ 0.461) and implant related complications (P ≥ 0.461) in the two groups of patients. Cost of implant in the PSR group range from N138,000 (for 2 level fusion) (1USD = N159) to ...

  18. “Symptomatic” Diabetic Peripheral Neuropathy Using Two Methods

    African Journals Online (AJOL)

    Background: Presence of symptoms of peripheral neuropathy (PN) in diabetes mellitus (DM) does not invariably indicate presence of underlying PN. Objective: To evaluate the objectivity of the symptoms of PN among DM subjects using two objective diagnostic instruments for PN – the United Kingdom Screening Test ...

  19. A comparison of two methods for fitting the INDCLUS model

    NARCIS (Netherlands)

    Ten Berge, Jos M.F.; Kiers, Henk A.L.

    2005-01-01

    Chaturvedi and Carroll have proposed the SINDCLUS method for fitting the INDCLUS model. It is based on splitting the two appearances of the cluster matrix in the least squares fit function and relying on convergence to a solution where both cluster matrices coincide. Kiers has proposed an

  20. Testing Two Methods that Relate Herbivorous Insects to Host Plants

    OpenAIRE

    White, Peter J. T.

    2013-01-01

    Insect herbivores are integral to terrestrial ecosystems. They provide essential food for higher trophic levels and aid in nutrient cycling. In general, research tends to relate individual insect herbivore species to host plant identity, where a species will show preference for one host over another. In contrast, insect herbivore assemblages are often related to host plant richness where an area with a higher richness of hosts will also have a higher richness of herbivores. In this study, the...

  1. Two methods of space-time energy densification

    International Nuclear Information System (INIS)

    Sahlin, H.L.

    1975-01-01

    With a view to the goal of net energy production from a DT microexplosion, two ideas (methods) are studied through which (separately or in combination) energy may be ''concentrated'' into a small volume and short period of time--the so-called space-time energy densification or compression. The advantages and disadvantages of lasers and relativistic electron-beam (E-beam) machines as the sources of such energy are studied and the amplification of laser pulses as a key factor in energy compression is discussed. The pulse length of present relativistic E-beam machines is the most serious limitation of this pulsed-power source. The first energy-compression idea discussed is the reasonably efficient production of short-duration, high-current relativistic electron pulses by the self interruption and restrike of a current in a plasma pinch due to the rapid onset of strong turbulence. A 1-MJ plasma focus based on this method is nearing completion at this Laboratory. The second energy-compression idea is based on laser-pulse production through the parametric amplification of a self-similar or solitary wave pulse, for which analogs can be found in other wave processes. Specifically, the second energy-compression idea is a proposal for parametric amplification of a solitary, transverse magnetic pulse in a coaxial cavity with a Bennett dielectric rod as an inner coax. Amplifiers of this type can be driven by the pulsed power from a relativistic E-beam machine. If the end of the inner dielectric coax is made of LiDT or another fusionable material, the amplified pulse can directly drive a fusion reaction--there would be no need to switch the pulse out of the system toward a remote target. (auth)

  2. Aerodynamic characteristics of spruce forest stand - comparison of two methods

    Czech Academy of Sciences Publication Activity Database

    Hurtalová, T.; Havránková, Kateřina; Janouš, Dalibor; Matejka, F.

    2002-01-01

    Roč. 5, č. 3 (2002), s. 17-22 ISSN 1335-339X R&D Projects: GA ČR GA526/00/0485 Institutional research plan: CEZ:AV0Z6087904 Keywords : wind speed profile * sonic anemometer * friction velocity Subject RIV: DG - Athmosphere Sciences, Meteorology

  3. Evaluating two methods of digital photography in retinopathy screening

    Directory of Open Access Journals (Sweden)

    Li Chen

    2018-02-01

    Full Text Available AIM:To evaluate the advantages of non-mydriatic fundus photography(NMFCSand mydriatic fundus photography(MFCSas eye-bottom screening and diagnosis methods in compared with gold standard fluorescein fundus angiography(FFA. METHODS: A total of 276 patients which involved in Chronic Diabetes Management Achieves within 4 streets of Pudong District Shanghai, were enrolled for diabetic retinopathy(DRexamination including NMFCS, MFCS and FFA. These DR examinations were proceeded after vision, slit-lamp and dioptroscopy tests, and reported by professionals. For those with suspicious fundus diseases, we would make appointments with specialist for further treatment. RESULTS: A total of 1104 colorful fundus images, and 1056 images(95.65%could be used to analyze. There were 408 appreciable images, 116 basically appreciable images and 28 unusable images in 552 NMFCS images. In addition, there were 432 appreciable images, 100 basically appreciable images and 20 unusable images in 552 MFCS images. There was no significant differences between NMFCS and MFCS(P>0.05. Compared with FFA with DRⅠ as the critical value, the specificity of digital photography for NMFCS was 95.71%, the sensitivity was 93.56%; however, MFCS are 95.43% and 98.02%. There was no statistically significant difference between the two screening methods(P>0.05. Compared with FFA with DRⅡ as the critical value, the specificity of digital photography for NMFCS was 95.35% and the sensitivity was 93.44%; however, for MFCS were 95.81% and 98.36%. There was no statistically significant difference between the two screening methods(P>0.05. CONCLUSION: Both NMFCS and MFCS could be used for the diagnosis and screening for eye diseases. NMFCS is easier and faster for digital photography, which is suitable for mass screening. MFCS is more likely to provide detailed information about the follow-up of the disease.

  4. Perancangan Controller

    OpenAIRE

    Santoso, Djunaidi

    2010-01-01

    In making controller, there must be knowledge about component controlling functions that used for controller designing. In the control unit, it needs simple method as micro programming. This micro programming is to create a micro program in binary numbering that used for controlling pin’s component controller and outside the controller. Controller design in general needs several prerequisites, which are digital system and controller and assembly language. 

  5. Effect of methylprednisolone pulse therapy with and without alendronate on biochemical markers of bone turnover in patients with Graves' ophthalmopathy.

    Science.gov (United States)

    Gasińska, Teresa; Borowska, Anna; Wichary, Hanna; Dec, Renata

    2012-01-01

     Immunosuppression with glucocorticoids is the method of choice in the treatment of active Graves' ophthalmopathy (GO). However, glucocorticoid therapy may have side effects, among others, it affects bone metabolism.  The aim of the study was to compare the effect of methylprednisolone pulse therapy (MPPT) with and without alendronate on bone turnover markers in patients with GO with normal and reduced bone mineral density (BMD).  The study included 53 patients with GO and 20 sex- and age‑matched healthy controls. Twenty patients with normal BMD (17 women, 3 men, aged 45 ±1.0 years) received only MPPT (8 g intravenously during 4 weeks). The remaining patients, with reduced BMD, were randomly assigned either to MPPT without alendronate (10 women, 2 men, aged 47 ±1.0 years) or MPPT with alendronate (18 women, 3 men, aged 47 ±1.0 years). BMD of the lumbar spine and femoral neck was assessed using dual energy X‑ray absorptiometry  (DEXA) before treatment. The markers of bone formation (serum osteocalcin, carboxyterminal propeptide of type I collagen [PICP], alkaline phospatase) and the markers of bone resorption (serum carboxyterminal telopeptide of type I collagen [ICTP], cross‑linked C‑terminal telopeptide of type I collagen [CTX], serum calcium [Ca] and potassium [P], as well as urinary excretion of deoxypyridinoline, Ca, and P) were determined before and after treatment.  MPPT caused a decrease in bone formation markers and an increase in some bone resorption markers. MPPT with alendronate decreased bone formation and bone resorption markers.  A negative effect of MPPT on bone turnover is observed both in patients with GO with normal and with reduced BMD. Simultaneous use of MPPT and alendronate in patients with GO and reduced BMD suppresses bone resorption caused by methylprednisolone.

  6. Improved Performance of Personalized Ventilation by Control of the Convection Flow around Occupant Body

    DEFF Research Database (Denmark)

    Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Krenek, Miroslav

    2009-01-01

    This paper reports on methods of control of the free convection flow around human body aiming at improvement of inhaled air quality for occupants at workstations with personalized ventilation (PV). Two methods of control were developed and explored: passive - blocking the free convection developm......This paper reports on methods of control of the free convection flow around human body aiming at improvement of inhaled air quality for occupants at workstations with personalized ventilation (PV). Two methods of control were developed and explored: passive - blocking the free convection...... development by modifications in desk design, and active - by local suction below the desk. The effectiveness of the two methods in enhancing the performance of PV was studied when applied separately and combined, and was compared with the reference case of PV alone. The experiments were performed in a full...

  7. Tracking the global maximum power point of PV arrays under partial shading conditions

    Science.gov (United States)

    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.

  8. The use of a micropore particle technology in the treatment of acute wounds.

    Science.gov (United States)

    Ryan, E

    2017-07-02

    A clinical audit was performed to evaluate whether Acapsil micropore particle technology (MPPT) powder could improve the management of acute wounds to heal by secondary intention. Wounds, which could be characterised as sloughy, wet and probably infected, normally managed by debridement followed by negative pressure wound therapy (NPWT), were included in the evaluation. The MPPT powder was applied topically to the wound surface either once daily or on alternate days, with each wound receiving a total of two to five applications. Most patients had NPWT after the MPPT powder treatment had finished to assist healing. The study included nine patients with dehisced surgical wounds and one with a category IV pressure ulcer (PU). The wounds were generally covered in slough, exudate and showing signs of local infection. The topical MPPT powder rapidly desloughed the wounds, controlled exudate levels, promoted granulation and was well tolerated. All wounds proceeded towards closure. Comparison of the present data with MPPT powder to standard treatment suggests that the speed of healing using MPPT was improved. Further examination is required to determine if this reduces dressing changes, nursing time, and financial cost.

  9. Controllable dose; Dosis controlable

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, J.T.; Anaya M, R.A. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico)]. E-mail: jtar@nuclear.inin.mx

    2004-07-01

    With the purpose of eliminating the controversy about the lineal hypothesis without threshold which found the systems of dose limitation of the recommendations of ICRP 26 and 60, at the end of last decade R. Clarke president of the ICRP proposed the concept of Controllable Dose: as the dose or dose sum that an individual receives from a particular source which can be reasonably controllable by means of any means; said concept proposes a change in the philosophy of the radiological protection of its concern by social approaches to an individual focus. In this work a panorama of the foundations is presented, convenient and inconveniences that this proposal has loosened in the international community of the radiological protection, with the purpose of to familiarize to our Mexican community in radiological protection with these new concepts. (Author)

  10. Dream controller

    Science.gov (United States)

    Cheng, George Shu-Xing; Mulkey, Steven L; Wang, Qiang; Chow, Andrew J

    2013-11-26

    A method and apparatus for intelligently controlling continuous process variables. A Dream Controller comprises an Intelligent Engine mechanism and a number of Model-Free Adaptive (MFA) controllers, each of which is suitable to control a process with specific behaviors. The Intelligent Engine can automatically select the appropriate MFA controller and its parameters so that the Dream Controller can be easily used by people with limited control experience and those who do not have the time to commission, tune, and maintain automatic controllers.

  11. 'Motor control center obsolescence'

    International Nuclear Information System (INIS)

    Irish, C.S.

    2003-01-01

    A significant and growing problem within the global nuclear industry is the aging of motor control center (MCC) components. MCC's have a very important role in the safety and critical to generation requirements of a nuclear power plant. Although many OEM's MCC's such as ITE/Telemechanique, GE, Westinghouse, Cutler Hammer, Klockner Moeller, etc. have been used throughout the global nuclear industry, they all have one common aspect obsolescence. Obsolescence of various components within the MCC's such as molded case circuit breakers, starters, relays, heaters, contactors, etc. are impacting the reliability of the MCC to serve its intended function. The paper will discuss the options which the nuclear industry is faced with to increase the reliability of the MCC's while maintaining design control, qualification and meeting budget constraints. The options as listed below shall be discussed in detail with examples to enhance the readers understanding of the situation: 1) Component by component replacement: The hurdles associated with trying to find equivalent components to replace the obsolete components while still worki (mechanically and electrically) in the original cubicle will be presented. 2) Complete MCC cubicle with new internal components replacement: The process of supplying a replacement cubicle, with all new internal components and new door to replace the original cubicle will be discussed. The presentation will conclude with a comparison of the advantages and dis-advantages of the two methods to bring the MCC to an as new condition with the overall goal of increasing reliability. (author)

  12. Adaptive control of nonlinear underwater robotic systems

    Directory of Open Access Journals (Sweden)

    Thor I. Fossen

    1991-04-01

    Full Text Available The problem of controlling underwater mobile robots in 6 degrees of freedom (DOF is addressed. Uncertainties in the input matrix due to partly known nonlinear thruster characteristics are modeled as multiplicative input uncertainty. This paper proposes two methods to compensate for the model uncertainties: (1 an adaptive passivity-based control scheme and (2 deriving a hybrid (adaptive and sliding controller. The hybrid controller consists of a switching term which compensates for uncertainties in the input matrix and an on-line parameter estimation algorithm. Global stability is ensured by applying Barbalat's Lyapunovlike lemma. The hybrid controller is simulated for the horizontal motion of the Norwegian Experimental Remotely Operated Vehicle (NEROV.

  13. Mosquito Control

    Science.gov (United States)

    ... Protection Agency Search Search Contact Us Share Mosquito Control About Mosquitoes General Information Life Cycle Information from ... Repellent that is Right for You DEET Mosquito Control Methods Success in mosquito control: an integrated approach ...

  14. Microwatt power consumption maximum power point tracking circuit using an analogue differentiator for piezoelectric energy harvesting

    Science.gov (United States)

    Chew, Z. J.; Zhu, M.

    2015-12-01

    A maximum power point tracking (MPPT) scheme by tracking the open-circuit voltage from a piezoelectric energy harvester using a differentiator is presented in this paper. The MPPT controller is implemented by using a low-power analogue differentiator and comparators without the need of a sensing circuitry and a power hungry controller. This proposed MPPT circuit is used to control a buck converter which serves as a power management module in conjunction with a full-wave bridge diode rectifier. Performance of this MPPT control scheme is verified by using the prototyped circuit to track the maximum power point of a macro-fiber composite (MFC) as the piezoelectric energy harvester. The MFC was bonded on a composite material and the whole specimen was subjected to various strain levels at frequency from 10 to 100 Hz. Experimental results showed that the implemented full analogue MPPT controller has a tracking efficiency between 81% and 98.66% independent of the load, and consumes an average power of 3.187 μW at 3 V during operation.

  15. Study of ciclosporine blood levels in patients after kidney or bone-marrow transplantation. Comparison between the two methods, fluorescence polarization immunoassay and radioimmunoassay. Etude de la ciclosporinemie de patients traites apres greffe de rein ou de moelle. Comparaison entre les methodes par immunofluorescence et radio-immunologique

    Energy Technology Data Exchange (ETDEWEB)

    Sadeg, N.; Pham Huy, C.; Claude, J.R. (Paris-5 Univ., 75 (FR)); Postaire, M.; Lebrec, H.; Hamon, M. (Paris-11 Univ., 92 - Chatenay-Malabry (FR) Hopital Necker-Enfants Malades, 75 - Paris (FR)); Broyer, M.; Gagnadoux, M.F.; Fischer, A. (Hopital Necker-Enfants Malades, 75 - Paris (FR))

    1989-01-01

    The apparition of ciclosporine, immunodepressive drug, has largely improved the organ transplantations. However, the range of blood concentrations must be defined to allow the efficacity of ciclosporine therapy and to avoid toxic reactions, because there are very important variations for a same dosage according to the individuals and the diseases. Relative to the low concentrations to be determined (about one hundred ng/ml), the most useful methods for ciclosporine measurement are based on immunochemical assays. This work compares the two methods: radioimmunoassay (RIA) and fluorescence polarization immunoassay (FPIA) simultaneously performed on several hundred samples. A very significant correlation exists between the two techniques (r = 0.80). The advantages of immunofluorescent assay consists in rapidity, sensibility and facility to realize emergency analysis.

  16. Dynamic Performance of Maximum Power Point Trackers in TEG Systems Under Rapidly Changing Temperature Conditions

    Science.gov (United States)

    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

  17. Control rods

    International Nuclear Information System (INIS)

    Maruyama, Hiromi.

    1984-01-01

    Purpose: To realize effective utilization, cost reduction and weight reduction in neutron absorbing materials. Constitution: Residual amount of neutron absorbing material is averaged between the top end region and other regions of a control rod upon reaching to the control rod working life, by using a single kind of neutron absorbing material and increasing the amount of the neutron absorber material at the top end region of the control rod as compared with that in the other regions. Further, in a case of a control rod having control rod blades such as in a cross-like control rod, the amount of the neutron absorbing material is decreased in the middle portion than in the both end portions of the control rod blade along the transversal direction of the rod, so that the residual amount of the neutron absorbing material is balanced between the central region and both end regions upon reaching the working life of the control rod. (Yoshihara, H.)

  18. Adaptive Feedback Linearization Based NeuroFuzzy Maximum Power Point Tracking for a Photovoltaic System

    Directory of Open Access Journals (Sweden)

    Sidra Mumtaz

    2018-03-01

    Full Text Available In the current smart grid scenario, the evolution of a proficient and robust maximum power point tracking (MPPT algorithm for a PV subsystem has become imperative due to the fluctuating meteorological conditions. In this paper, an adaptive feedback linearization-based NeuroFuzzy MPPT (AFBLNF-MPPT algorithm for a photovoltaic (PV subsystem in a grid-integrated hybrid renewable energy system (HRES is proposed. The performance of the stated (AFBLNF-MPPT control strategy is approved through a comprehensive grid-tied HRES test-bed established in MATLAB/Simulink. It outperforms the incremental conductance (IC based adaptive indirect NeuroFuzzy (IC-AIndir-NF control scheme, IC-based adaptive direct NeuroFuzzy (IC-ADir-NF control system, IC-based adaptive proportional-integral-derivative (IC-AdapPID control scheme, and conventional IC algorithm for a PV subsystem in both transient as well as steady-state modes for varying temperature and irradiance profiles. The comparative analyses were carried out on the basis of performance indexes and efficiency of MPPT.

  19. Control apparatus

    International Nuclear Information System (INIS)

    Doll, D.W.

    1977-01-01

    A nuclear reactor system is described in which flexible control rods are used to enable insertion of the control rods into guide holes in the core which are distributed over an area larger than the cross section of the control rod penetration in the reactor pressure vessel. Guide tubes extend from the penetration and fan out to the guide holes for guiding the control rods from the penetration to the guide holes

  20. Helicopter controllability

    OpenAIRE

    Carico, Dean

    1989-01-01

    Approved for public release; distribution is unlimited The concept of helicopter controllability is explained. A background study reviews helicopter development in the U.S. General helicopter configurations, linearized equations of motion, stability, and piloting requirements are discussed. Helicopter flight controls, handling qualities, and associated specification are reviewed. Analytical, simulation and flight test methods for evaluating helicopter automatic flight control systems ar...