bluuebunny/crossref_metadata_2025 huggingface dataset:
Geomorphology Characterization of Ica Basin and Its Influence on the Dynamic Response of Soils for Urban Seismic Hazards in Ica, Peru
Authors: Bernal Isabel , Tavera Hernando , Sulla Wilfredo , Arredondo Luz , Oyola Javier
Published: January 2018

We evaluated the influence of the geomorphology of Peru’s Ica Basin on the dynamic response of soils of the city of Ica. We applied five geophysical methods: spectral ratio (H/V), frequency-wavenumber (F-K), multichannel analysis of surface waves (MASW), multichannel analysis of microtremor (MAM), and Gravimetric Analysis. Our results indicate that the soils respond to two frequency ranges:F0(0.4–0.8 Hz) andF1(1.0–3.0 Hz). TheF-K, which considers circular arrays, shows two tendencies with a jump between 1.0 and 2.0 Hz. MASW and MAM contribute to frequencies greater than 2.0 Hz. The inversion curve indicates the presence of three layers of 4, 16, and 60 m with velocities of 180, 250, and 400 m/s. The Bouguer anomalies vary between −17.72 and −24.32 mGal and with the spectral analysis we identified two deposits, of 60 m and 150 m of thickness. Likewise, the relationship between the velocities of 400 and 900 m/s, with the frequency = 1.5 Hz, allows us to determine the thickness for the layers of 60 (slightly alluvial to moderately compact) and 150 m (soil-rock interface). These results suggest that the morphology of the Ica Basin plays an important role in the dynamic behavior of the soils to low frequency.
Underestimated Cost of Targeted Attacks on Complex Networks
Authors: Ren Xiao-Long , Gleinig Niels , Tolić Dijana , Antulov-Fantulin Nino
Published: January 2018

The robustness of complex networks under targeted attacks is deeply connected to the resilience of complex systems, which is defined as the ability to make appropriate response to the attack. In this paper, we study robustness of complex networks under a realistic assumption that the cost of removing a node is not constant but rather proportional to the degree of a node or equivalently to the number of removed links a removal action produces. We have investigated the state‐of‐the‐art targeted node removing algorithms and demonstrate that they become very inefficient when the cost of the attack is taken into consideration. For the case when it is possible to attack or remove links, we propose a simple and efficient edge removal strategy named Hierarchical Power Iterative Normalized cut (HPI‐Ncut). The results on real and artificial networks show that the HPI‐Ncut algorithm outperforms all the node removal and link removal attack algorithms when the same definition of cost is taken into consideration. In addition, we show that, on sparse networks, the complexity of this hierarchical power iteration edge removal algorithm is only O(n log2+ε⁡n).
DICER1 and Associated Conditions: Identification of At-risk Individuals and Recommended Surveillance Strategies
Authors: Schultz Kris Ann P. , Williams Gretchen M. , Kamihara Junne , Stewart Douglas R. , Harris Anne K. , Bauer Andrew J. , Turner Joyce , Shah Rachana , Schneider Katherine , Schneider Kami Wolfe , Carr Ann Garrity , Harney Laura A. , Baldinger Shari , Frazier A. Lindsay , Orbach Daniel , Schneider Dominik T. , Malkin David , Dehner Louis P. , Messinger Yoav H. , Hill D. Ashley
Published: January 2018

Pathogenic germline DICER1 variants cause a hereditary cancer predisposition syndrome with a variety of manifestations. In addition to conferring increased cancer risks for pleuropulmonary blastoma (PPB) and ovarian sex cord–stromal tumors, particularly Sertoli–Leydig cell tumor, individuals with pathogenic germline DICER1 variants may also develop lung cysts, cystic nephroma, renal sarcoma and Wilms tumor, nodular hyperplasia of the thyroid, nasal chondromesenchymal hamartoma, ciliary body medulloepithelioma, genitourinary embryonal rhabdomyosarcoma, and brain tumors including pineoblastoma and pituitary blastoma. In May 2016, the International PPB Registry convened the inaugural International DICER1 Symposium to develop consensus testing and surveillance and treatment recommendations. Attendees from North America, Europe, and Russia provided expert representation from the disciplines of pediatric oncology, endocrinology, genetics, genetic counseling, radiology, pediatric surgery, pathology, and clinical research. Recommendations are provided for genetic testing; prenatal management; and surveillance for DICER1-associated pulmonary, renal, gynecologic, thyroid, ophthalmologic, otolaryngologic, and central nervous system tumors and gastrointestinal polyps. Risk for most DICER1-associated neoplasms is highest in early childhood and decreases in adulthood. Individual and caregiver education and judicious imaging-based surveillance are the primary recommended approaches. These testing and surveillance recommendations reflect a consensus of expert opinion and current literature. As DICER1 research expands, guidelines for screening and treatment will continue to be updated. Clin Cancer Res; 24(10); 2251–61. ©2018 AACR.
Oral Health and Brain Injury: Causal or Casual Relation?
Authors: Pillai Rajath Sasidharan , Iyer Kiran , Spin-Neto Rubens , Kothari Simple Futarmal , Nielsen Jørgen Feldbæk , Kothari Mohit
Published: January 2018

Background: To systematically review the current literature investigating the association between oral health and acquired brain injury. Methods: A structured search strategy was applied to PubMed, Embase, Web of Science, and CENTRAL electronic databases until March 2017 by 2 independent reviewers. The preferred reporting items for systematic review and meta-analysis guidelines were used for systematic review. Results: Even though the objective was to assess the association between oral health and acquired brain injury, eligible studies focused solely on different forms of stroke and stroke subtypes. Stroke prediction was associated with various factors such as number of teeth, periodontal conditions (even after controlling for confounding factors), clinical attachment loss, antibody levels to Aggregatibacter actinomycetemcomitans and Prevotella intermedia. The literature showed no consensus on the possible association between gingivitis and stroke. Patients with stroke generally had poorer oral hygiene practices and oral health. Dental prophylaxis and professional intervention reduced the incidence of stroke. Conclusions: Overall, oral health and stroke were related. Periodontitis and tooth loss were independently associated with stroke. However, prevention and timely intervention may reduce the risk of stroke. Stroke was the main cerebral lesion studied in the literature, with almost no publications on other brain lesions.
Allogrooming in Male-Female Pairs of Captive Owl Monkeys (Aotus nancymaae)
Authors: Wolovich Christy K. , Tapanes Elizabeth , Evans Sian
Published: January 2018

Owl monkeys (Aotus spp.) are socially monogamous, yet allogrooming is reported to be rare. Because Aotus are nocturnal and arboreal, allogrooming is difficult to observe in natural settings. We observed 21 male-female pairs of captive Aotus nancymaae during 2 nonconsecutive study periods in order to describe the details of allogrooming between mates (partner grooming). We found that grooming bouts are brief and consist of tugging the hair or skin with flexed fingers and/or the mouth. Males groomed females most often, and their rates of partner grooming were negatively related to age. Partner grooming occurred regardless of mating behavior. Camera trap data revealed that the rate of partner grooming (1.50 bouts/h) is greater than that recorded from our direct observations in the early evenings (0.51 bouts/h, in 2013; 0.37 bouts/h in 2003) given that most bouts occurred later in the night. A positive relationship between the rates of the parents' partner grooming and those of their offspring later in life suggests intergenerational transmission. This relationship is influenced by the fathers' rates of partner grooming. We conclude that allogrooming in Aotus is a normal part of their behavioral repertoire that likely serves social functions similar to those in other pair-bonded primates.
Transjugular Intrahepatic Portosystemic Shunt in Patients with Portal Hypertension: Patency Depends on Coverage and Interventionalist’s Experience
Authors: Buechter Matthias , Manka Paul , Gerken Guido , Canbay Ali , Blomeyer Sandra , Wetter Axel , Altenbernd Jens , Kahraman Alisan , Theysohn Jens M.
Published: January 2018

Background and Aims: Transjugular intrahepatic portosystemic shunt (TIPS) is the treatment of choice in decompensated portal hypertension. TIPS revision due to thrombosis or stenosis increases morbidity and mortality. Our aim was to investigate patient- and procedure-associated risk factors for TIPS-revision. Patients and Methods: We retrospectively evaluated 189 patients who underwent the TIPS procedure. Only patients who required TIPS revision within 1 year (Group I, 34 patients) and patients who did not require re-intervention within the first year (Group II [control group], 54 patients) were included. Results: Out of 88 patients, the majority were male (69.3%) and mean age was 56 ± 11 years. Indications for TIPS were refractory ascites (68%), bleeding (24%), and Budd-Chiari syndrome (8%). The most frequent liver disease was alcohol-induced cirrhosis (60%). Forty-three patients (49%) received bare and 45 patients (51%) covered stents, thus resulting in reduction of hepatic venous pressure gradient (HVPG) from 19.0 to 9.0 mm Hg. When comparing patient- and procedure-related factors, the type of stent (p < 0.01) and interventionalist’s experience (number of performed TIPS implantations per year; p < 0.05) were the only factors affecting the risk of re-intervention due to stent dysfunction, while age, gender, indication, Child-Pugh, and model of end-stage liver disease score, platelet count, pre- and post-HVPG, additional variceal embolization, stent diameter, and number of stents did not significantly differ. Conclusion: Patients undergoing TIPS procedure should be surveilled closely for shunt dysfunction while covered stents and high-level experience are associated with increased ­patency.
Neural Stem Cells Expressing bFGF Reduce Brain Damage and Restore Sensorimotor Function after Neonatal Hypoxia-Ischemia
Authors: Ye Qingsong , Wu Yanqing , Wu Jiamin , Zou Shuang , Al-Zaazaai Ali Ahmed , Zhang Hongyu , Shi Hongxue , Xie Ling , Liu Yanlong , Xu Ke , He Huacheng , Zhang Fabiao , Ji Yiming , He Yan , Xiao Jian
Published: January 2018

Background/Aims: Neonatal hypoxia-ischemia (HI) causes severe brain damage and significantly increases neonatal morbidity and mortality. Increasing evidences have verified that stem cell-based therapy has the potential to rescue the ischemic tissue and restore function via secreting growth factors after HI. Here, we had investigated whether intranasal neural stem cells (NSCs) treatment improves the recovery of neonatal HI, and NSCs overexpressing basic fibroblast growth factor (bFGF) has a better therapeutic effect for recovery than NSCs treatment only. Methods: We performed permanent occlusion of the right common carotid artery in 9-day old ICR mice as animal model of neonatal hypoxia-ischemia. At 3 days post-HI, NSC, NSC-GFP, NSC-bFGF and vehicle were delivered intranasally. To determine the effect of intranasal NSC, NSC-GFP and NSC-bFGF treatment on recovery after HI, we analyzed brain damage, sensor-motor function and cell differentiation. Results: It was observed that intranasal NSC, NSC-GFP and NSC-bFGF treatment decreased gray and white matter loss area in comparison with vehicle-treated mouse. NSC, NSC-GFP and NSC-bFGF treatment also significantly improved sensor motor function in cylinder rearing test and adhesive removal test, however, NSC-bFGF-treatment was more effective than NSC-treatment in the improvement of somatosensory function. Furthermore, compared with NSC and NSC-GFP, NSC-bFGF treatment group appeared to differentiate into more neurons. Conclusion: Taken together, intranasal administration of NSCs is a promising therapy for treatment of neonatal HI, but NSCs overexpressing bFGF promotes the survival and differentiation of NSCs, and consequently achieves a better therapeutic effect in improving recovery after neonatal HI.
FOC of SRM using More Efficient DC-DC Converter Topology
Authors: S. Abdel-Aliem Emad
Published: January 2018

Numerous studies had been made to improve the switched reluctance motor operation depend on the modification of the machine design, proposing the converter designs and/or applying a suitable control method. This paper introduces the field orientation control method for that motor using a simple and very efficient DC-DC converter topology. This control method is presented by two techniques; first technique is the advance of the turn-on switching angle and the other technique is the retard/delay of the turn-off switching angle. Instantaneous and average motor characteristics are obtained using Matlab/Simulink software package. Comparison between the simulation results presented using two converter types. A precise speed and torque control are obtained. The average total torque per current is maximized.
Different Control Schemes for Sensor Less Vector Control of Induction Motor
Authors: Gangishetti Srinivas , Sandipamu Tarakalyani
Published: January 2018

This paper deals with the design of different control schemes for sensorless vector control of induction motor.Induction motor is most widely used A.C. Motor but  the major draw back is flux and torque cannot be controlled individually.This can be obtained by implementing  sensorless vector control methods.The control strategy of induction motor  is by different controllers like conventional control methods and artificial intelligence control methods.The conventional control methods are sensitive to parameter changes and will not be accurate. This paper proposes to design a controller to over come the above draw backs by using intelligent control techniques like fuzzy logic, artificial neutral networks (ANN) and genetic algorithm (GA).The above conventional control methods are compared with intelligent control techniques. The simulation studies are carried out using Matlab/Simulink and the wave forms for speed, torque and voltage components for various controlles are plotted. Numerical analysis for speed and torque components considering parameters like peakover shoot and peak time are presented.
Periodic Perturbation Method for Controlling Chaos for a Positive Output DC-DC Luo Converter
Authors: Balamurugan P. , Kavitha A. , Sanjeevikumar P. , Daya J.L. Febin , Sutikno Tole
Published: January 2018

A simple, non-feedback method of controlling chaos is implemented for a DC-DC converter. The weak periodic perturbation (WPP) is the control technique applied to stabilize an unstable orbit in a current-mode controlled Positive Output Luo (POL) DC-DC converter operating in a chaotic regime. With WPP, the operation of the converter is limited to stable period-1 orbit that exists in the original chaotic attractor. The proposed control strategy is implemented using simulations and the results are verified with hardware setup. The experimental results of the converter with WPP control are presented which shows the effectiveness of the control strategy.
Cascaded Symmetric Multilevel Inverter with Reduced Number of Controlled Switches
Authors: Muhammad Tila , Khan Adnan Umar , Jan Hanif , Usman Muhammad Yasir , Javed Junaid , Aslam Arsalan
Published: January 2018

Multilevel inverters have become popular among high power converters for the past few years due to their high quality output waveform and low total harmonic distortions (THD). In addition, the filter size also reduces significantly to achieve a pure sine wave output. Cascaded H-Bridge topology has been recognized as the most promising among various classical topologies for multi-level inverters on the basis of its modular form and ease of design, troubleshooting, packaging and high power capabilities. However, a large number of switches are required in cascaded H-Bridge multilevel inverter that leads to larger system losses and an increase in cost. In this paper the modified cascaded topology is proposed to reduce the number of controlled switches without affecting the resolution of output waveform or the number of voltage levels. We achieved this by replacing some of the high cost controlled transistor switches with diodes, in the cascaded H-Bridges. Furthermore, equal voltage source sharing is also possible by using the proposed topology. Hence the proposed inverter is a type of cascaded multilevel inverter with reduced switches, better modular structure, low cost and high efficiency. The inverter design is validated using simulations and tested on hardware prototype.
Performance Analysis of Modified SVPWM Strategies for Three Phase Cascaded Multi-level Inverter fed Induction Motor Drive
Authors: Bhukya Ravikumar , Kumar P. Satish
Published: January 2018

This paper presents new modified space vector pulse width modulation techniques (Phase disposition-Space vector pulse width modulation, Alternative Phase Opposition disposition- Space vector pulse width modulation and Phase Opposition disposition-Space vector pulse width modulation) are analyzed for three-phase cascaded multi-level inverter fed induction motor from the point of view of the Phase voltages, line voltage, stator current,speed,torque and Total harmonic distortion.in the proposed modified technique the reference signals are generated by adding offset voltage to the reference phase voltages.This modified SVPWM technique does not involve region indentification,sector identification for switching vector determination as are required in the conventional multi level SVPWM technique,it is also reduces the computation time compared to the conventional space vector PWM technique.The necessary calculations for generation of new modified SVPWM for the modulation strategies have presented in detail.  It is observed that the modified SVPWM modulation ensures excellent, close to optimized pulse distribution results and THD is compared to for five-level, seven-level, nine-level and eleven-level Cascaded H-Bride Multi-level Inverter fed to Induction motor. Theoretical investigations were confirmed by the digital simulations using MATLAB/SIMULINK software.
Effects of Switching Frequency Modulation on Input Power Quality of Boost Power Factor Correction Converter
Authors: Stepins Deniss , Huang Jin
Published: January 2018

Switching frequency modulation (SFM) as spread-spectrum technique has been used for electromagnetic interference reduction in switching power converters. In this paper, a switching-frequency-modulated boost power factor correction (PFC) converter operating in continuous conduction mode is analysed in detail in terms of its input power quality. Initially, the effect of SFM on the input current total harmonic distortion, power factor and low-frequency harmonics of the PFC converter are studied by using computer simulations. Some advices on choosing parameters of SFM are given. Then the theoretical results are verified experimentally. It is shown that, from a power quality point of view, SFM can be harmful (it can significantly worsen the power quality of the PFC converter) or almost harmless. The results depend on how properly the modulation parameters are selected.
Performance Evaluation and Comparison of Two Cascaded Configurations of PV Generators-Five Levels Inverter for a Stand-Alone Application in South Algeria
Authors: Benamrane Karima , Benslimane Tarak , Abdelkhalek Othmane , Abdelkrim Thameur , Borni Abdelhalim
Published: January 2018

In this paper two configurations of solar photovoltaic energy conversion using the NPC five levels inverter for stand-alone application in south Algeria are proposed and their performances compared. The first cascade uses four separate PV sources and the second configuration use only one PV generator. In these two cases and without DC/DC converter introduced between PV source and inverter and to get a stable AC voltage, authors in propose a proportional regulator of inverter modulation index. The SVPWM technique is used in order to get the best voltage waveform. For the second configuration proposed, we introduce in the control loops another algorithm which uses the redundant vectors of space vector diagram of inverter to stabilise the DC bus voltages. A real data of temperature and solar irradiation obtained by radiometric station in Ghardaïa city in south Algeria are used to test the performance of proposed controls. The simulation results show that the inverter output voltage is stable for the two configurations proposed despite the variation of solar irradiation, temperature and load. Also, the THD obtained is in the limits of international standards. Then, the PV cascade with separate PV sources is the best solution, seeing that we do not need to use another algorithm in the control loops.
Analysis and Impact of D-STATCOM, Static Var Compensator, Fuzzy Based SVC Controller on the Stability of a Wind Farm
Authors: Rabyi Kaoutar , Mahmoudi Hassane
Published: January 2018

In recent years, applications of facts systems have been developed for the compensation of active and reactive power. Facts systems are electronics devices that are connected to the wind farm. This paper presents the impacts of some of these devices on the stability of a wind farm, especially D-STATCOM, Static Var Compensator and Fuzzy SVC controller. First, a presentation of D-STATCOM, SVC, then fuzzy logic controller. In simulation study, the D-STATCOM ensures the stability of the voltage and current at the point of connection with the electrical grid. Finally, Comparing the SVC to the F-SVC simulations, we notice that the F-SVC is more performed than SVC for the compensation of the active and reactive power.
Constant Switching Frequency and Torque Ripple Minimization of DTC of Induction Motor Drives with Three-level NPC Inverter
Authors: Ismail Huzainirah , Patkar Fazlli , Jidin Auzani , Jidin Aiman Zakwan , Noor Azlan Noor Azida , Sutikno Tole
Published: January 2018

Direct Torque Control (DTC) is widely applied for ac motor drives as it offers high performance torque control with a simple control strategy. However, conventional DTC poses some disadvantages especially in term of variable switching frequency and large torque ripple due to the utilization of torque hysteresis controller. Other than that, performance of conventional DTC fed by two-level inverter is also restricted by the limited numbers of voltage vectors which lead to inappropriate selection of voltage vectors for different speed operations. This research aims to propose a Constant Switching Frequency (CSF) torque controller for DTC of induction motor (IM) fed by three-level Neutral-Point Clamped (NPC) inverter. The proposed torque controller utilizes PI controller which apply different gain for different speed operation. Besides, the utilization of NPC inverter provides greater number of voltage vectors which allow appropriate selection of voltage vectors for different operating condition. Using the proposed method, the improvement of DTC drives in term of producing a constant switching operation and minimizing torque ripple are achieved and validated via experimental results.
Improvement of Torque Capability of Direct Torque Control of Induction Machines
Authors: Jidin Auzani , Lai Sim New , Sutikno Tole
Published: January 2018

A control strategy for overmodulation operation of direct torque control hysteresis based in induction machine is proposed. The strategy is to extend the constant torque region as well as to improve the torque capability. The proposed overmodulation strategy is different to SVM based system where the reference stator voltage is available. In order for DTC hysteresis based system to be able to achieve that, several modifications have been applied so that the proposed overmodulation can be achieved by gradually transforming the PWM voltage waveform to six-step mode. Simulated results were provided to demonstrate the effectiveness of the strategy.
Performance Evaluation of Dynamic Voltage Restorer Based on Transformer-based Z Source Inverter
Authors: Chinmay V. Deshpande , Chaitanya V. Deshpande , Sanjay A. Deokar
Published: January 2018

In this paper, latest technology is introduced in substitution to conventional voltage and current type inverter with Transformer based impedance (Z) source inverter in voltage sag assessment and mitigation and compared with voltage source inverter based dynamic voltage restorer. Transformer based impedance source inverters (Trans-Z source inverters) are newly proposed inverters that can be used to overcome downside of voltage source inverter, current source inverter and impedance source (Z-source) inverter. T-Z source inverter consists of transformer with high frequency and low leakage inductance along with low reactive component compared with conventional Z source inverter. In case of T-Z source inverter, voltage stress throughout Z-source capacitor is reduced along with inrush current limitation at startup. This paper presents modeling of T-Z source inverter based dynamic voltage restorer using MATLAB/SIMULINK software along with its THD analysis which is compared with VSI based dynamic voltage restorer. Here abc to dq0 control algorithm is employed. The control technique which is employed for simulation shows excellent results for voltage sag and swell compensation.
Performances Analysis of a Linear Motor for Sliding Door Application
Authors: Lachheb Aymen , Khediri Jalel , El Amraoui Lilia
Published: January 2018

The present work deals to investigate the performance of linear switched reluctance motor designed for a sliding door application. The objective of this paper is to develop an analytical model in order to predict the dynamic behaviour of the studied motor. Firstly, the characteristics of the proposed motor in open loop operation was computed.Secondly, the effect of the load on the response of the motor was investigated. In this context, a two technoque in open loop were adopted to solve the error positioning with load and to damp the oscillation observed in the characteristics of the motor in order to obtain a smooth motion.
Indirect Pulse-vector Control of Wound Rotor Induction Motor Drive in ANSYS Electromagnetics Suite
Authors: Funk Tatiana Andreevna , Usynin Yuriy Semenovich , Belousov Evgeniy Viktorovich
Published: January 2018

This paper deals with the problem of estimation of rotor angular position for the indirect pulse-vector control of wound rotor induction motor drive. The paper considers issues of thematic justification and expanding of the field of using sensorless motor drives. With a view to improve energy consumption readings during design and modernization of motor drives of massive mechanisms with moderate standards for accuracy of velocity control, requiring long-term velocity decrease during load reduction (according to technological process conditions), using the system of the pulse-vector control of wound rotor induction motor is suggested. The paper provides the solution for the problem of developing math models of this motor drive system both for the motor-mounted sensor, and for indirect angular position sensing. The models were developed in ANSYS Electromagnetics Suite using the finite element method for studying electromagnetic processes. Based on the models, the investigation of transition and steady states of a motor drive was carried out, process quality parameters were obtained, namely: max and root-mean-square currents, torques; velocity control errors caused by pulse operation mode. From that simulation, the result illustrates the effectiveness of the proposed approach.
Performance Comparison of Fuzzy Logic and Proportional-integral for an Electronic Load Controller
Authors: Irfan Muhammad , Effendy Machmud , Alif Nur , Syafaah Lailis , Pakaya Ilham , Faruq Amrul
Published: January 2018

Generally, Electronic Load Control (ELC) used in micro hydro power plant (MHPP) to controls the voltage between consumer load and a dummy load, still detects one parameter voltage or frequency generator only. Whereas in reality, any changes in the load on consumers, generator voltage and frequency also changed. When the consumer load down the electric current will be supplied to the dummy load, amounting to decrease in consumer load. When there is a transfer load, there will be distortion voltage and frequency, thus a special methods to reduce distortions by speeding up the process of transferring the electric load is needed. The proposed of this study is using fuzzy logic algorithm.To realize such a system, a comparison tool model of load control digital electronic fuzzy logic controller (FLC) and Proportional Integrator (PI) is required. This modeling using matlab program to simulate, the simulation result shows that the ELC based  on fuzzy logic controller is better than conventional PI control, it seen from fast response to steady state condition.
Selective Harmonic Elimination Based on Newton-raphson Method for Cascaded H-bridge Multilevel Inverter
Authors: Abd Halim Wahidah , Tengku Azam Tengku Noor Ariana , Applasamy Komathi , Jidin Auzani
Published: January 2018

Multilevel inverters are emerging as the new breed of power converter options for high power applications. They typically synthesis the staircase voltage waveform (from several dc sources) which reduced harmonic content. This paper presents a simple selective harmonic elimination (SHE) modulation for single-phase cascaded H-bridge (CHB) multilevel inverter. The optimum switching angle of the transcendental equations describing the fundamental and harmonic components is solved by means of the Newton-Raphson (NR) method. The proposed SHE scheme is performed through simulation using MATLAB/Simulink. This simulation results are then verified through experiment using Altera DE0-Nano field-programmable gate array (FPGA). The proposed SHE is efficient in eliminating the lowest-order harmonics and producing a higher quality output waveform with a better harmonic profile.  
The Coordinated Control of FACTS and HVDC Using H-infinity Robust Method to Stabilize the Inter-regional Oscillations in Power Systems
Authors: Zadehbagheri Mahmoud , Pishavaie Mehrdad , Ildarabadi Rahim , Sutikno Tole
Published: January 2018

This paper presents a new resistant control method for synchronized connection of FACTS & HVDC aiming to get the stability of small signal of the power system. The efficiency of the proposed controller on the stability of the entire tested system has been proved and also guarantees the stability against uncertainty and turmoil. Applying this method can also reduce the difficulties of oscillations between adjacent areas to generator without strengthening transmission lines or costly constraints on system performance. The simulation results on a system of 68 buses, 16 generators and 5 areas show that the mentioned controller with embedded HVDC and SVC has significant performance despite changes in parameters.
Implementation of Coupled Inductor Based 7-level Inverter with Reduced Switches
Authors: Palanisamy R. , Vijayakumar K. , Bagchi Aishwarya , Gupta Vachika , Sinha Swapnil
Published: January 2018

This paper proposes implementation of coupled inductor based 7 level inverter with reduced number switches. The inverter which generates the sinusoidal output voltage by the use of coupled inductor with reduced total harmonic distortion. The voltage stress on each switching devices, capacitor balancing and common mode voltage can be minimized. The proposed system which gives better controlled output current and improved output voltage with diminished THD value. The switching devices of the system are controlled by using hysteresis current control algorithm by comparing the carrier signals with constant pulses with enclosed hysteresis band value. The simulation and experimental results of the proposed system outputs are verified using matlab/Simulink and TMS320F3825 dsp controller respectively.
Modeling and Fuzzy Logic Control of PV Based Cascaded Boost Converter Three Phase Five-level Inverter System
Authors: Revana Guruswamy , Reddy Kota Venkata
Published: January 2018

Power Quality development using PV based boost cascaded inverter system is one of the reliable methods. This paper handle with modeling and fuzzy logic control of boost to boost cascaded three phase inverter system with PV as source. MATLAB simulink model for BBCIS has been developed using the elements of simulink and cascaded loop investigations are performed with PI and Fuzzy Logic Controllers. The dynamic responses of the above systems are compared in terms of time domain parameters. The consequences point to that maximum power is obtained with minimum THD using FLC.
Fractional Order PID Controlled PV Buck Boost Converter with Coupled Inductor
Authors: D Vanitha , Rathinakumar M.
Published: January 2018

Buck-boost converter is a good interface between PV and the load. This paper deals with comparison between PI and FOPID controlled PV fed Buck Boost Converter with Coupled Inductor (PVBBCCI) systems. Open loop PVBBCCI system, closed loop PI controlled PVBBCCI and FOPID based PVBBCCI systems are designed, modeled and simulated using Simulink and their results are presented. The investigations indicate the superior performance of FOPID controlled PVBBCCI system. The proposed system has advantages like reduced hardware count enhanced dynamic response and improved stability.
Self-tuning Position Control for the Linear Long-stroke, Compound Switched Reluctance Conveyance Machine
Authors: Pan J. F. , Wang Weiyu , Bo Zhang , Cheung Norbert , Qiu Li
Published: January 2018

This paper proposes a long-stroke linear switched reluctance machine (LSRM) with a primary and a secondary translator for industrial conveyance applications. The secondary one can translate according to the primary one so that linear compound motions can be achieved. Considering the fact that either one translator imposes a time-variant, nonlinear disturbance onto the other, the self-tuning position controllers are implemented for the compound machine and experimental results demonstrate that the absolute steady-state error values can fall into 0.03 mm and 0.05 mm for the secondary and primary translator, respectively. A composite absolute precision of less than 0.6 mm can be achieved under the proposed control strategy.
Reactive Power Compensation in Industrial Grid via High-power Adjustable Speed Drives with Medium Voltage 3L-NPC BtB converters
Authors: A. A. Radionov A.A., , R. Gasiyarov Vadim , S. Maklakov Alexander , Ekaterina A. Maklakova
Published: January 2018

The objective of this study is to develop and research a new method of reactive power compensation in industrial grid via high-power adjustable speed drives (HP ASDs) with medium voltage (MV) three level neutral point clamped back-to-back (3L-NPC BtB) converters. The article is concerned with the mathematical description, control system designing and obtaining of experimental results. An important advantage of the new method is that specialized equipment is not necessary for its implementation. The analysis of our experimental research shows that the developed reactive power compensation method has been successfully applied for main HP ASD of plate mill rolling state 5000 (Magnitogorsk Iron and Steel Works, PJSC). Some ways for future industrial application prospects and improvements of the designed method are outlined in the conclusion of the paper.
Design of DC-DC Boost Converter with Negative Feedback Control for Constant Current Operation
Authors: Rao L Navinkumar , Gairola Sanjay , Lavety Sandhya , Islam Noorul
Published: January 2018

In this paper design of DC-DC boost converter with constant current control, charging is presented to charge the battery of electric vehicles. The different methods of battery charging are discussed. The charging profile of different types of batteries is investigated and compared with respect to charging time. The battery current is sensed and compared with a reference current and the generated actuating signal which is an error is feed to PI controller to compute a duty cycle of boost converter for constant current operation. A 6 V dc supply is obtained by using a step down transformer and diode rectifier. Boost converter parameters are designed for continuos conduction mode operation. The limiting values of duty cycle are fixed in the range of 0.5 to 0.6 for constant current operation. Simulation is carried out using MATLAB software for constant current operation connected to a 50 Ah, 12 V battery load. The constant current operation is achieved using negative feedback control. The switching frequency of boost converter is set to 20 kHz. The filter components are also designed to reduce ripple content within limited values. The simulation result shows the effectiveness of charging control for hardware implementation.
Comparative Study of Three Different Topologies of Five-Level Inverter with SPWM Modulation Technique
Authors: Farah Nabil , Bt. Mat Lazi Jurifa , Talib MHN
Published: January 2018

Multilevel Inverter (MLI) has attracted a great attention by different researchers and industries due to its capability in handling high power application and minimizing the harmonics contents in the output. This study propose three different topologies of MLI (5-level) which are Cascaded H-Bridge Multilevel Inverter (CHMLI) ,Diode Clamped Multilevel Inverter and Flying Capacitor Multilevel Inverter (FCMLI) .These three topologies have been modelled in MATLAB/SIMULINK and compared in terms of THD and number of components used. Sinusoidal Pulse Width Modulation is utilized to control both of the topologies with same DC source. The results showed that ,CHMLI is superior compared to DCMLI and FCMLI in which the CHMLI produce 26.29% THD while DCMLI and FCMLI produce 29.14% and 33.53% respectively .Moreover less components and switching losses is obtained when using the CHMLI.
Proportional Integral Estimator of the Stator Resistance for Direct Torque Control Induction Motor Drive
Authors: Chaudhari Jagdish Gangadharrao , Bodkhe Sanjay Bhauraoji , Aware Mohan V.
Published: January 2018

In this paper, an improved proportional integral stator resistance estimation for a direct torque controlled induction motor is proposed. This estimation method is based on an on-line stator resistance correction regarding the variations of the stator current estimation error. In fact, the input variable of the PI estimator is the stator current estimation error. The main idea is to tune accurately the stator resistance value relatively to the evolution of the stator current estimation error gradient to avoid the drive instability and ensure the tracking of the actual value of the stator resistance. But there is an unavoidable steady state error between the filtered stator current modulus and its estimated value from the dq model of the machine which is due to pseudo random commutations of the inverter switches. An offset has been introduced in order to overcome this problem, for different speed command values and load torques. Simulation results show that the proposed estimator was able to successfully track the actual value of the stator resistance for different operating conditions
Design of an Improved MPPT Control of DFIG Wind Turbine under Unbalanced Grid Voltage using a Flux Sliding Mode Observer
Authors: Majdoub Youssef , Abbou Ahmed , Akherraz Mohamed , El Akhrif Rachid
Published: January 2018

This study presents a control scheme of the electronic interface of a grid connected Variable Speed Wind Energy Generation System (VS-WEGS) based on a Doubly Fed Induction Generator (DFIG). The efficiency of the wind energy is represented to according to the control strategy applied. Thus, in the case of unbalanced grid voltage, the negative sequence voltage causes additional strong oscillation at twice the grid frequency in the stator instantaneous active and reactive powers. The objective of this work is to present an enhanced MPPT controller uses backstepping approach implemented in both  and   reference frames rotating to keep a safe operation of DFIG during unbalanced grid voltage associated with regulating rotor flux, in order to estimate rotor flux, a nonlinear observer based on sliding mode is proposed in this work. Note that the conventional controllers (PI, PI-R …) are not provided satisfactory performance during unbalanced voltage dips. The validation of results has been performed through simulation studies on a 4 kW DFIG using Matlab/Simulink®.
Practical Performance Evaluation of Maximum Power Point Tracking Algorithms in a Photovoltaic System
Authors: Abouobaida Hassan , Said EL Beid
Published: January 2018

This paper addresses a performance evaluation of maximum power point tracking techniques (MPPT) in a photovoltaic system. This research work finds its applications in photovoltaic systems producing electric power with a better energy efficiency, which will lead to an improved relationship between the cost and the amount of the produced power. The importance of this work resides on the one hand in the evaluation of the performances of the different MPPTs according to three criteria instead of one or two criteria in other works of the literature and on the other hand in the study of Four algorithms in one paper and their comparisons. This paper discusses the performance evaluation of the MPPT algorithms called P&O, Inc-Cond, Hill-Climbing and Fuzzy algorithms based simulation results and practical validation. The performances of these algorithms are evaluated according to the following criteria: The response time, the amplitude of the oscillations around the optimal point and the accuracy. The objectives in this article are summarized in the following points: (a) modeling the photovoltaic systems, (b) presenting and detailing each MPPT algorithm (c) presenting and discussing the simulation results in Matlab/Simulink and practical validation (d) evaluating the performance of each algorithm. This paper is completed by a summary on the areas of use for each algorithm and conclusions.
Photovoltaic Thermal (PVT) System with and Without Fins Collector: Theoretical Approach
Authors: Zohri Muhammad , Nurato Nurato , Fudholi Ahmad
Published: January 2018

The fins collector design for solar thermal has widely been used and it has a higher thermal efficiency than without Fins. Photovoltaic thermal (PV/T) system produced Electrical and thermal energy instantaneously. Mathematical modeling based on steady-state thermal analysis of PV/T system with and without fins was conducted with matrix inversion method. The value results show that the PV/T system with fins collector is higher thermal and electrical efficiency than without fins.
A Time-Frequency Transform Based Fault Detectionand Classificationof STATCOM Integrated Single Circuit Transmission Line
Authors: Mishra Sanjay Kumar , Swain S.C , Tripathy L.N
Published: January 2018

 

 

This paper discusses the time-frequency transform based fault detection and classification of STATCOM (Static synchronous compensator) integrated single circuit transmission line. Here, fast-discrete S-Transform (FDST) based time-frequency transformation is proposed for evaluation of fault detection and classification including STATCOM in transmission line. The STATCOM is placed at mid-point of transmission line. The system starts processing by extracting the current signals from both end of current transformer (CT) connected in transmission line. The current signals from CT’s are fed to FDST to compute the spectral energy (SE) of phase current at both end of the line. The differential spectral energy (DSE) is evaluated by subtracting the SE obtained from sending end and SE obtained from receiving end of the line. The DSE is the key indicator for deciding the fault pattern detection and classification of transmission line. This proposed scheme is simulated using MATLAB simulink R2010a version and successfully tested under various parameter condition such as fault resistance (Rf),source impedance (SI), fault inception angle (FIA) and reverse flow of current. The proposed approach is simple, reliable and efficient as the processing speed is very fast to detect the fault within a cycle period of FDT (fault detection time).
Control strategy of a grid-connected photovoltaic with battery energy storage system for hourly power dispatch
Authors: Jusoh Mohd Aﬁﬁ , Daud Muhamad Zalani
Published: January 2018

The high penetration of ﬂuctuated photovoltaic (PV) output power into utility grid system will aﬀect the operation of interconnected grids. The unnecessary output power ﬂuctuation of PV system is contributed by unpredictable nature and inconsistency of solar irradiance and temperature. This paper presents a control scheme to mitigate the output power ﬂuctuations from PV system and dispatch out the constant power on an hourly basis to the utility grid. In this regards, battery energy storage (BES) system is used to eliminate the output power ﬂuctuation. Control scheme is proposed to maintain parameters of BES within required operating constraints. The eﬀectiveness of the proposed control scheme is tested using historical PV system input data obtained from a site in Malaysia. The simulation results show that the proposed control scheme of BES system can properly manage the output power ﬂuctuations of the PV sources by dispatching the output on hourly basis to the utility grid while meeting all required operating constraints.
A Study on 3-phase Interleaved DC-DC Boost Converter Structure and Operation for Input Current Stress Reduction
Authors: Harimon M. A. , Ponniran A. , Kasiran A. N. , Hamzah H. H.
Published: January 2018

This paper analyses a 3-phase interleaved DC-DC boost converter for the conversion of low input voltage with high input current to higher DC output voltage. The operation of the 3-phase interleaved DC-DC boost converter with multi-parallel of boost converters is controlled by interleaved of switching signals with 120 degrees phase-shifted. Therefore, with this circuit configuraion, high input current is evenly shared among the parallel units and consequently the current stress is reduced on the circuit and semiconductor devices and contributes reduction of overall losses. The simulation and hardware results show that the current stress and the semiconductor conduction losses were reduced approximately 33% and 32%, respectively in the 3-phase interleaved DC-DC boost converter compared to the conventional DC-DC boost converters. Furthermore, the use of interleaving technique with continuous conduction mode on DC-DC boost converters is reducing input current and output voltage ripples to increase reliability and efficiency of boost converters.
A JUDICIALIZAÇÃO DA SAÚDE CONTEXTUALIZADA NA DIMENSÃO PRÁTICA DAS REPRESENTAÇÕES SOCIAIS DOS PROFISSIONAIS DE SAÚDE
Authors: Ramos Raquel de Souza , Gomes Antonio Marcos Tosoli , Guimarães Raphael Mendonça , Santos Érick Igor dos
Published: January 2018

A judicialização da saúde é uma expressão cada vez mais presente no Brasil, materializada principalmente pelos mandados judiciais para a realização de procedimentos diagnósticos e terapêuticos, consultas, internações e dispensação de insumos médico-cirúrgicos. Este artigo visa a analisar e discutir os conteúdos da representação social da judicialização, contextualizada na dimensão prática das representações sociais dos profissionais de saúde. O estudo qualitativo, pautado na Teoria das Representações Sociais, entrevistou 40 profissionais em um hospital universitário e na central de regulação de procedimentos e leitos na cidade do Rio de Janeiro. A análise se deu pela técnica de análise de conteúdo temático-categorial, instrumentalizada pelo software NVivo, resultando em 725 unidades de registro, distribuídas em 34 temas. Identificou-se que os profissionais apresentam um posicionamento negativo diante da realidade imposta pela judicialização, embora reconheçam esse recurso como necessário mediante a crise da saúde pública. Considerando a representação social como determinante de práticas, conclui-se que as representações oriundas deste estudo se encontram em fase de consolidação e podem influenciar a mudança das práticas dos profissionais em busca de melhorias na assistência direta aos usuários, caracterizando-se, portanto, um desafio maior no sentido de fazer avançar a democracia e a cidadania.