196 research outputs found
Module Level Electronic Circuit based PV array for Identification and Reconfiguration of Bypass Modules
No full textIn this paper, a novel electronic circuit based on opto-coupler is designed for each module of photovoltaic (PV) array to deal with partial shading conditions. The proposed circuit not only provides electronic monitoring at the module level but also ensures the reconfiguration of bypass modules. The control framework of the proposed scheme works in two steps. In Step-1, the PV array is connected in series-parallel (SP) configuration and the power-voltage (P-V) curve is traced to search the global maximum (GM). In Step-2, bypass modules are separated from PV array through their respective electronic circuits in a decentralized control manner, and the power of bypass modules is
stored in the battery. The proposed electronic circuit provides a low cost solution as it is free from expensive sensing and complex
switching network. Moreover, the control operation of proposed scheme is simple. The proposed scheme is verified through computer-aided simulations and a hardware prototype of 170 W. The comparative study indicates that the proposed scheme yields more energy than past proposed solutions
Efficient MPP Tracking of Photovoltaic (PV) Array Through Modified Boost Converter With Simple SMC Voltage Regulator
No full textSliding mode controller (SMC) based MPPT systems are less effective due to input LCin tank of boost converter. The LCin tank at PV node creates the sinusoidal waves of V-pv/I-pv, due to which phase angle (phi) occurs between triangular wave of inductor current (I-L) and sinusoidal V-pv. This creates the adverse effects on SMC operation. In this research work, a series capacitor based boost converter is developed without using the parallel LCin circuit. Consequently, V-pv/I-pv becomes triangular (pure/semi) and phi factor between V-pv and triangular I-L is minimized. The proposed setup ensures a high frequency operation and better voltage regulation of SMC. Through theoretical, mathematical and experimental studies, the response of PV source with conventional converter and proposed converter have been analyzed. Finally, extensive simulation studies and experimental evidences are presented, which highlights the superior dynamic and steady efficiencies of PV system with proposed topology as opposed to conventional converter and other recently developed MPPT systems
An intelligent control strategy of fractional short circuit current maximum power point tracking technique for photovoltaic applications
No full textThis paper presents an improved Fractional Short Circuit Current (FSCC)
Maximum Power Point Tracking (MPPT) technique in which an additional control
loop is used to find the proper moment to measure the SCC. The target is to reduce
the power losses in MPPT process that occur as a result of intermittent time based
short circuit current measurements. The proposed modification enables the
conventional FSCC MPPT to decide intelligently about the measurement of SCC
thus reduces the number of times the photovoltaic (PV) module is isolated from the
load. Although number of algorithms for tracking MPPT has been reported, the
proposed method suits well for low cost PV applications. A Matlab/Simulink based
model is employed to test the functional abilities of the proposed method. The
comparison of the proposed method and conventional time based FSCC method is
also presented in the simulation analysis. Finally, a 130W prototype based on the
dSPACE DS1104 controller and experimental results are presented to verify the
effectiveness of the proposed method. The technique is verified under uniform
shading conditions. The results show satisfactory performance against test
conditions
A two stage hybrid maximum power point tracking technique for photovoltaic applications
No full textPhotovoltaic (PV) systems are widely used now a days for coping the growing energy demands all across the globe. The non-linear behavior of the characteristic curve of solar module requires special arrangement to harvest maximum amount of power. To track the Maximum Power Point (MPP) across the non linear IV curve of PV module, techniques are used in addition to the power electronic circuit and are called Maximum Power Point Tacking (MPPT). Various methods of MPPT exists in literature, each bearing its own pros and cons. In this paper we presents a novel technique to improve the performance of conventional Perturb and Observe (P&O) algorithm of MPPT. Our technique removes the drawbacks of P&O under rapidly changing environmental conditions. It also executes less power oscillations under steady state conditions. The algorithm is a hybrid of Fractional Short Circuit current (FSCC) and P&O algorithms. The system takes the advantage of rapid tracking near to MPP using the FSCC and then carry on to track the exact MPP using the traditional P&O technique. The technique is verified through simulation using Matlab/SIMULIN
A new irradiance sensorless hybrid MPPT technique for photovoltaic power plants
No full textA hybrid Maximum Power Point Tracking (MPPT) method without using an irradiance sensor is proposed in this paper. The hybrid MPPT method is a combination of conventional Perturb and Observe (P&O) and Fractional Short Circuit Current (FSCC) MPPT technique. The proposed hybrid MPPT decides intelligently about the initial operating point of P&O by using the FSCC MPPT method. This method requires no sensor for irradiation measurement because it detects intelligently about the change in irradiance. Therefore, under dynamic weather conditions the decision about measuring the initial operating point of P&O is intelligent. After finding the initial operating point the system shifts to the conventional P&O method and starts to perturb with a small perturbation size. The use of small perturbation steps enables the system to work with less power oscillations around the Maximum Power Point (MPP), while the use of FSCC helps in rapid tracking of MPP especially under the varying environmental conditions. Thus, the proposed method is fast in tracking the MPP with less power oscillations and hence better performance in terms of energy harvesting when compared with the conventional P&O technique. Impedance matching between solar panel and load is achieved using a DC-DC boost converter and the proposed method is simulated in MATLAB/SIMULINK environment. The system is simulated against the steady and dynamic weather conditions. The results shows that under steady weather condition the proposed method harvests 5% extra energy as compared with the conventional P&O. For dynamic weather conditions the proposed method harness an additional 3.5% energy when compared with the P&O method, which makes it very promisin
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
A propos des origines du « style animalier »
No full textThe Author, who is Professor of archaeology and a specialist of rock art in Central Asia examines the various theories about the origin of the scytho-siberian animal style. Prof. Sher refutes the theory of Middle Eastern origin, principally based on the discovery of the so-called « Ziwiye hoard ». Furthermore, the scientific excavation of the kurgan Arzhan (Tuva) offers strong evidence for an early datation (between 12th and 9th centuries B.C.) for the representations of the first period of this animal style, contemporary to the Karasuk culture (Late Bronze, Early Iron Age). These representations, on rock, as well as on stelae (the « deer stelae ») and artefacts, are rooted in the Early Bronze Age representations of the Okunevo and Afanasevo cultures in the Minusinsk basin and neighbouring areas. Prof. Sher traces some stylistic elements and their evolution from South Siberia towards Central Asia and further West, where they meet Middle Eastern influences.Sher Jakov A. A propos des origines du « style animalier ». In: Arts asiatiques, tome 47, 1992. pp. 5-18
A Reconfiguration Circuit to Boost the Output Power of a Partially Shaded PV String
No full textAn optical isolator circuit is developed to detect and dynamically relocate the photovoltaic (PV) module under partial shading. The suggested system control structure operates in two modes. Mode 1 governs the system at global maxima (GM) by tracing the power-voltage (PV) curve. Mode 2 detects and separates all the bypassed modules from a PV string/array by means of a decentralized control and stores its power in the battery. Simulations are performed on different shading patterns to verify the efficacy of the suggested system. The results showcase that the averaged harnessed power using the proposed circuit is 25.26% more than the total cross-tied (TCT) and series-parallel (SP) array configurations. The proposed circuit does not require complex gate driver circuits and large switch counts. The circuit is scalable and can be implemented on an “N × N” array
DETECTION AND IDENTIFICATION OF SEED BORNE BACTERIA OF MAIZE AND THEIR MANAGEMENT WITH SELECTED Cu-FUNGICIDES
No full textA Thesis
Submitted to the Faculty of Agriculture,
Sher-e-Bangla Agricultural University, Dhaka,
in partial fulfillment of the requirements for the degree of
Master of Science
In
Plant Pathology
Semester: January-June, 2011Approved by:
Nazneen Sultana
Chairman
Examination Committee
Department of Plant Pathology
Sher-e-Bangla Agricultural University, Dhaka
Nazneen Sultana
Associate Professor
Department of Plant Pathology
Supervisor
Mrs. Nasim Akhtar
Professor
Department of Plant Pathology
Co-Supervisor
Ref:………… Date:…………….
CERTIFICATE
This is to certify that thesis entitled, “DETECTION AND IDENTIFICATION OF SEED BORNE BACTERIA OF MAIZE AND THEIR MANAGEMENT WITH SELECTED Cu-FUNGICIDES” submitted to the Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in PLANT PATHOLOGY, embodies the result of a piece of bona fide research work carried out by KADAMBARI ROY, Registration No: 05-01829 under my supervision and guidance. No part of the thesis has been submitted for any other degree or diploma.
I further certify that such help or source of information, as has been availed of during the course of this investigation has been duly been acknowledged by her.
Nazneen Sultana
Associate Professor
Department of Plant Pathology
Sher-e-Bangla Agricultural University
Dhaka-1207, Bangladesh
Email: nazneensau @yahoo.com
Cell No.01733955171
………………………………..
( NAZNEEN SULTANA )
Supervisor
Dated: 20th September, 2012
Dhaka, Bangladesh
DEDICATED TO
MY
BELOVED PARENTS
ACKNOWLEDGEMENT
First and foremost the author would like to thank Almighty God for what he has given to the author and whose abundant grace and mercy has enabled for successful completion of the research, preparation of manuscript its submission in time as a partial requirement for the degree of MS (Master of Science) in Plant pathology.
And after that the author expresses her greatful respect, wishes, whole hearted gratitude and appreciation to her benevolent teacher and supervisor Associate Professor and Chairman Nazneen Sultana, Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, for her precious suggestions, constructive criticism, proper guidance and helpful comments through out the study.
The author expresses with a deep sense of respect to her Co-supervisor Mrs. Nasim Akhtar Professor, Department of plant Pathology, Sher-e-Bangla Agricultural University, Dhaka for her cordial inspiration, guidance and helpful suggestions for its improvement. Her scholastic supervision and constant inspiration brought this thesis up to its present standard.
Cordial thanks and honors to Dr. Md. Rafiqul Islam, Professor, Department of plant Pathology, Sher-e-Bangla Agricultural University, Dhaka for his valuable advice, criticism, suggestions and provision of facilities and support needed to undertake this research work.
The authoress expresses her sincere appreciation and gratitude to her respectable teachers, Professor Dr. M. Salauddin M. Chowdhury and Associate Professor Dr.F.M. Aminuzzaman Department of plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, for their inspiration and encouragement throughout the whole period of the research work.
The author also conveys her special thanks to Shanjida Haque, Nargis Islam Roni, Mamun-or-Rashid and Matin Sarkar for their cordial co-operation whenever required. The author is greatful to the office staffs of the Department of Plant Pathology for their co-operation and help.
The whole credit for the achievements goes to the author’s family and highly gratitude to her great father Late Upendra Nath Roy, mother Jothsna Roy, sister and brother who always stood by her during tough times. They supported, encouraged her continuously to study and blessing in all phases of her academic life; they were motivators from near or far. They were her strength and their constant encouragement was an inspiration.
June, 2011
Place: SAU, Dhaka The Author
DETECTION AND IDENTIFICATION OF SEED BORNE BACTERIA OF MAIZE AND THEIR MANAGEMENT WITH SELECTED Cu-FUNGICIDES
BY
KADAMBARI ROY
REGISTRATION NO. : 05-1829
ABSTRACT
The experiment was carried out in the Department of Plant Pathology of Sher-e-Bangla Agricultural University, Dhaka during the period of January, 2012 to August, 2012 to determine the prevalence of seed borne bacteria of hybrid maize variety NK-40 and their management with some selected Cu-fungicides. Three bacterial genera viz. Acidovorax sp, Burkholderia sp and Ralstonia sp were isolated from maize seeds. Moreover, three Cu-fungicides viz. Sulcox 50WP, Champion 50WP and Cupravit 50WP were used as treatments for management. Bioassay of these fungicides against different bacteria were done and observed that Sulcox 50WP @ 0.3%, Champion 50WP @ 0.4% and Cupravit 50WP @ 0.3% produced remarkable inhibition zone against Acidovorax sp, Burkholderia sp and Ralstonia sp. Effect of seed treatments were studied using nutrient agar plate method, water agar test tube method and rolled paper towel method. In nutrient agar plate method, germination varied from 94.83-98.67%, where the effect of Cu-fungicides was insignificant. In water agar test tube method, the highest number of normal seedlings (69.00%) were recorded when seeds were treated with Cupravit 50WP @ 0.3% and the lowest was recorded in control (44.67%). The lowest number of abnormal seedlings and diseased seedlings (20% and 5%, respectively) were recorded when the seeds were treated with Cupravit 50WP @ 0.3%. In rolled paper towel method, Cupravit 50WP @ 0.3% showed best performance regarding germination, shoot length, root length and vigor index. The vigor index varied from 885.50-2488.40, where the highest count was recorded in Cupravit 50WP @ 0.3% and lowest in control
- …
