Simulation, Measurement, and Emulation of Photovoltaic Modules Using High Frequency and High Power Density Power Electronic Circuits

The number of solar photovoltaic (PV) installations is growing exponentially, and to improve the energy yield and the efficiency of PV systems, it is necessary to have correct methods for simulation, measurement, and emulation. PV systems can be simulated using PV models for different configurations and technologies of PV modules. Additionally, different environmental conditions of solar irradiance, temperature, and partial shading can be incorporated in the model to accurately simulate PV systems for any given condition. The electrical measurement of PV systems both prior to and after making electrical connections is important for attaining high efficiency and reliability. Measuring PV modules using a current-voltage (I-V) curve tracer allows the installer to know whether the PV modules are 100% operational. The installed modules can be properly matched to maximize performance. Once installed, the whole system needs to be characterized similarly to detect mismatches, partial shading, or installation damage before energizing the system. This will prevent any reliability issues from the onset and ensure the system efficiency will remain high. A capacitive load is implemented in making I-V curve measurements with the goal of minimizing the curve tracer volume and cost. Additionally, the increase of measurement resolution and accuracy is possible via the use of accurate voltage and current measurement methods and accurate PV models to translate the curves to standard testing conditions. A move from mechanical relays to solid-state MOSFETs improved system reliability while significantly reducing device volume and costs. Finally, emulating PV modules is necessary for testing electrical components of a PV system. PV emulation simplifies and standardizes the tests allowing for different irradiance, temperature and partial shading levels to be easily tested. Proper emulation of PV modules requires an accurate and mathematically simple PV model that incorporates all known system variables so that any PV module can be emulated as the design requires. A non-synchronous buck converter is proposed for the emulation of a single, high-power PV module using traditional silicon devices. With the proof-of-concept working and improvements in efficiency, power density and steady-state errors made, dynamic tests were performed using an inverter connected to the PV emulator. In order to improve the dynamic characteristics, a synchronous buck converter topology is proposed along with the use of advanced GaNFET devices which resulted in very high power efficiency and improved dynamic response characteristics when emulating PV modules

Effects of beta-1,3-D glucan on systemic bortezomib treated rat pancreas

Bortezomib, selective inhibitor of the 26S proteasome, is used for treatment of some types of cancer and immunosuppressive therapies. B-1,3(D)-glucan, a synthetic antioxidant is used complementary medical treatment for human. This study was conducted to investigate the effects of the antioxidant Beta-1,3-D glucan on rat pancreas treated with systemic bortezomib. In the study, 36 Sprague-Dawley adult male rats were divided into four groups: control (C), bortezomib (BZ), β-1, 3-D-glucan (BD) and bortezomib + β-1,3- (D) –glucan (BZ+BD). Each group was divided into two subgroups (48 or 72 hours), depending on the time of scarification. After experiments, immunohistochemical, stereological and histopathological changes in all rat pancreatic tissues were examined. It was determined increased degenerative, vacuolated serous acini cells and inflammatory cell infiltrations in the groups of BZ and BZ+BG. In immunohistochemical analysis, densities of insulin positive cells were decreased in the groups of BZ and BZ+BG. Furthermore, in stereological mean volume of serous acinus analysis, significantly increases were detected in the groups of BZ and BZ+BG (p<0.05). BZ treatment had the detrimental effects on pancreas tissues. Also, administration of BG was insufficient to prevent injury induced by BZ treatment in the pancreas tissues

Modelling and evaluation of light railway system’s noise using neural predictors

Background: Noise is defined as a sound or series of sounds that are considered to be invasive, irritating, objectionable and disruptive to the quality of daily life. Noise is one of the environmental pollutants, and in cities it is usually originated from road traffic, railway traffic, airports, industry etc. The tram is generally considered as environmentally friendly, namely non-polluting and silent. However complaints from residents living along the tramway lines prove that it may sometimes cause annoyance. In this study, a Global Pointing System (GPS) receiver for determining the sampling locations and a frequency based noise measurement system for collecting the noise data are used to analyse the noise level in the city centre. Both environmental (background) and tram noises are measured

PERFORMANCE ANALYSIS OF WEB-BASED RELATIVE AND PRECISE POINT POSITIONING TECHNIQUES WITH DIFFERENT SATELLITE VISIBILITY CONDITIONS

The Global Navigation Satellite System (GNSS) is used for precise positioning applications, such as surveying and geodesy. The aim of the present work is to evaluate the effectiveness of web-based relative positioning (RP) and precise point positioning (PPP) GNSS post-processing services using measurements of different satellite visibility obstacles. Within this framework, static GNSS observations were conducted at three control benchmarks selected taking the impact of natural and human-made obstacles on satellite signals into consideration. 3 hours of static GNSS observations in Istanbul, Turkey were repeatedly obtained from three control BMs over six days and were evaluated through two RP (AUSPOS, OPUS) and three PPP (CSRS-PPP, Magic-PPP, GAPS-PPP) web-based GNSS post-processing services. The 6-day average of the three control benchmark coordinates computed using the Bernese GPS software v5.0, and were accepted as true results. They were compared to the local coordinates acquired through the RP and PPP web-based GNSS post-processing services. The different satellite visibility conditions were found to have significant effects on the GNSS point positioning solutions. We also found that web-based GNSS post-processing services provide easy and effective solutions for geodetic positioning applications

INVESTIGATION OF REPEATABILITY OF DIGITAL SURFACE MODEL OBTAINED FROM POINT CLOUDS IN A CONCRETE ARCH DAM FOR MONITORING OF DEFORMATIONS

Applicability of Terrestrial Laser Scanners/Scanning (TLS) in deformation measurement in dams is an active area of study. With the advance of modern technology, accuracy of measurements is much improved by developments in design of terrestrial laser scanners. Currently, this technology is used in large and complex engineering structures such as dams. Although TLS is a high cost technology, it is particularly used in monitoring of dam deformations, due to its speed in obtaining thousands of data points, ability to visualize the scanned object and its environment with high accuracy and ability to take long-range measurements. In order to determine the effect of change in water reservoir levels on body of the dam, TLS are used to take deformation measurements in different time intervals, where the water level was at maximum, minimum and medium levels. This paper provides an overview of terrestrial laser scanning technology for deformation monitoring. The concrete arch dam in Antalya Oymapinar, Turkey was used for case study. Four different scannings were performed in this dam in order to verify the replicability of TLS results on same water levels and equivalent conditions. Digital Surface Models reflecting dam surface have been created. Results obtained from surface model differences were examined using surface matching method.

Antimicrobial, antibiofilm potential, and anti-quorum sensing activity of silver nanoparticles synthesized from Cyanobacteria Oscillatoria princeps

Cyanobacteria are among the beneficial and environmentally friendly natural candidates used in the biosynthesis of nanoparticles, with their ability to accumulate heavy metals from their environment, thanks to their biologically active compounds. In the current study, an aqueous extract of Oscillatoria princeps fresh biomass was used for the green synthesis of AgNPs. UV-vis spectrum, Fourier transforms infrared, scanning electron microscopy, and energy-dispersive spectroscopy were used to validate and characterize biosynthesized of OSC-AgNPs. The biosynthesis of AgNPs was visually verified in terms of the change in the color of the AgNO3 solution from yellowish brown to brown colors from 72 h onwards. An absorption peak of approximately 420 nm was detected in the UV-vis spectrum, corresponding to the plasmon resonance of AgNPs. FT-IR analysis showed the presence of free amino groups in addition to sulfur-containing amino acid derivatives that act as stabilizing agents. SEM images detected the roughly spherical shape of OSC-AgNPs with an average size of 38 nm. The pathogens tested were all susceptible to OSC-AgNPs showing varying antimicrobial effects on pathogenic microorganisms. E. coli and C. albicans displayed the maximum susceptibility, with zones of inhibition of 14.6 and 13.8 mm at 3-mM concentration, respectively, while B. cereus had the lowest zone of inhibition (10.6 mm) at 3-mM OSC-AgNO3 concentration. In conclusion, AgNPs synthesized from Oscillatoria princeps inhibit biofilm formation, suggesting that AgNPs may be a promising candidate for the prevention and treatment of biofilm-associated infections caused by bacteria and yeasts

SÜNEN-İ NESÂÎ [NÜSHALARININ] RİVAYETİ

Ebu Abdurrahman Ahmed b. Şuayb b. Ali b. Sinan b. Bahr b. Dînâr en-Nesâî Horasan [bölgesindeki] Nesâ’da 215 yılında doğdu.1 On beş yaşına gelince Horasan’daki meşhur hadisçi Kuteybe b. Saîd’i ziyaret etmek için yola çıktı ve on dört ay süre ile ondan ilim tahsil etti.2 Horasan, Cezîre, Suriye, Mısır ve Hicaz’da pek çok kişiden hadis dinledi ve Kahire’ye yerleşip, Zukâku’l-Kanâdîl’de hayatını sürdürdü.3 Fıkıh, sahih ve zayıf hadisler ve isnatlarda ismi geçen şahıslar hakkındaki bilgisi ile büyük bir şöhret kazandı. Hâkim 321–405 , hâfız Ebu Ali [en-Neysâbûrî] 277–349 ’nin; gördüğü Müslümanların dört imamını zikrederken Nesâî’yi en başta zikrettiğini birçok defa duyduğunu söylemektedir

HiCRi lll. ASlR iTiBARiYLE BAGDAT'TA HADiS. FAALiYETLERiNE GENEL BiR BAKlŞ

Bağdat, Abbasi halifesi EbU Ca'fer el-Mansur (ö.l581775) tarafından 1451762 yılında kurulmuş ve Medinetu's-selam ismi verilmiştir. Akabinde buraya pek çok alim yerleşmiştir. Abbas! halifelerinin gayret ve destekleri sonucunda da kısa sürede bir ilim, kültUr ve medeniyet şehri haline gelmişrir. Şehirde ikinci ve üçüncü asır boyunca hadis, tefsir, fıkıh ve kelam alanlarında önemli çalışmalar yapılmıştır. Üçüncü hicri asırda, hadiste otorite olan pek çok alim çok değerli eserler kaleme almışlardır. Ahmed b. Hanbel (164-241/780-855), oğl].l Abdullah (213-290/828-903), İbn Sa'd (168- 2301784-844) ve Yahya b. Main ((158-2331774-847) bu alimlerden sadece birkaçıdır. Bu çalışmada Bağdat'ta yetişen eser sahibi bazı önemli hadisçilerin biyografılerini ortaya koyup, eserlerine işaret etmiş bulunmaktayız

KAZVÎN ŞEHRİNİN FAZİLETİNE DAİR BİR RİVÂYETİN SENEDİ ÜZERİNE BİR İNCELEME

Bazı bölgeler ve şehirler hakkında Hz. Peygamber s.a.v ’e isnad edilen pek çok rivâyet vardır. Bu rivâyetlerin bir kısmında o bölge ve şehirler övülürken, bir kısmında da yerilmektedir. Ne var ki hadis otoriteleri, ilgili rivâyetlerin büyük çoğunluğunun uydurma olduğu kanaatindedirler. Araştırmamızın konusunu teşkil eden Kazvîn şehrinin faziletiyle ilgili rivâyet de çoğu hadis otoritesi tarafından uydurma olarak kabul edilmiştir. Buna gerekçe olarak da rivâyetin isnadındaki bazı râvîlerin hadis uydurucusu vaddâ’ olduğu ileri sürülmüştür. Bu çalışmada ilgili rivâyet isnad tenkidine tabi tutulmuştur. Bu bağlamda Kazvîn hakkında kısa bir bilgi verdikten sonra rivâyetin tarikleri tespit edilmiş, daha sonra da râvîlerin cerh ve ta’dil durumları ele alınmıştı

HiCRi lll. ASlR iTiBARiYLE BASRA'DA HADiS FAALiYETLERiNE GENEL BiR BAKlŞ

Basra, Hz. Ömer'in emriyle Utbe b. Gazvan (ö.17/638) tarafından 14-16/635- 637 yılları arasında kurulmuştur. Akabinde Ebü Musa el-Eş'ari (ö.44/665), Enes b. Malik (ö.931712) ve Muğlre b. Şu'be (ö.S0/670) gibi pek çok sahabi buraya yerleşmiş ve "Bas,pı Mektebi"ni kurmuştur. İlk üç a~_ır boyunca dil, kıraat, fıkıh, tefsir ve hadis alanlarında önemli çalışmalar yapılmıştır. U çüncü hicri asırda, hadiste otorite olan pek çok alim çok değerli eserler kaleme almışlardır. Ebu Davud et-Tayiiiisi (ö.I33- 2Q4/750-819), Ali b. el-Medini (ö.161-234/777-849) ve Ebu Diivud es-Sicistani (ö.202-275/81 7-889) bu alimlerden sadece birkaçı dır. Bu çalışmada Basra'da yetişen eser sahibi bazı önemli hadisçilerin biyografılerini ortaya koyup, eserlerine işaret etmiş bulunmaktay ız