2,358 research outputs found
LCL Filter Design for Single-Phase Grid-Connected PV Inverters with Double-frequency Unipolar PWM Switching
No full textThe current injected by PV inverters to the grid must contain low harmonic content within the standard limitations. However, the output voltage of inverters consists of large harmonic components at switching frequencies due to the PWM switching. Thus, an LCL filter is normally installed at the inverter output to efficiently reduce the current harmonics. Among different PWM switching schemes, double-frequency unipolar PWM has drawn little attention due to the issue of common-mode leakage current in transformerless inverters. However, this switching method offers advantages such as a lower harmonic content and higher efficiency. This paper paves the way for the implementation of double-frequency PWM switching scheme in transformerless single-phase grid-connected PV inverters by introducing a detailed description on LCL filter design. Theoretical and simulation studies on a complete PV converter are conducted in MATLAB/SIMULINK to prepare a straightforward LCL filter design procedure
Pengajian Tasawuf Guru Abdus Syukur Al-Hamidi (Studi Terhadap Ajaran Tasawuf)
No full textPenelitian ini dilakukan atas dasar pengajian bercorak tasawuf yang hadir di tengah-tengah kehidupan modern kota Banjarmasin. Tasawuf dalam kehidupan modern setidaknya memiliki dua persoalan yang kontradiktif. Pertama, tasawuf tidak relevan dengan kemajuan Islam dan modernitas dikarenakan ajarannya yang dianggap berlawanan dengan daya potensi manusia. Kedua, di satu sisi, kehadiran modernitas melahirkan krisis spiritual dan manusia seperti menjadi musuh bagi manusia lain.Pengajian tasawuf Guru Abdus Syukur Al-Hamidi menjadi penting untuk diungkap ajaran dan pengajiannya terkait dengan persolan di atas.
Dalam penelitian ini permasalahan yang diteliti adalah bagaimana konsep ajaran tasawuf yang dikembangkan oleh Guru Abdus Syukur Al-Hamidi? Bagaimana karakteristik Tasawuf yang diajarkan oleh Guru Abdus Syukur Al-Hamididankontekstualisasi?
Penelitianiniadalahpenelitiankualitatiftentangpengajian tasawuf yang diadakanolehGuru Abdus Syukur Al-Hamidi. Olehkarenaitu, pendekatan yang digunakanadalahtasawuf. Adapun hasil penelitian ini adalah menunjukkan dua hal yakni; 1) konsep yang diajarkan oleh guru Abdus Syukur al-Hamidi adalah ajaran takhalli, tahalli dan tajalli. Denganajaraninibeliauinginmelakukanpenyucian zahir dan bathin dari segala perbuatan dan sifat yang tidak sesuai dengan apa yang diajarkan oleh Allah dan Rasul SAWbagipengikutnya. 2) Karakteristik tasawuf yang diajarkan oleh Guru Abdus Syukur Al-Hamidi merupakan tasawuf akhlaki (amali), di mana beliau mengajarkan tentang sifat-sifat terpuji, membersihkan zahir dan bathin, serta mencapai jalan ma’rifat melalui proses penyucian diri sekaligus pengisian hati untuk menanamkan sifat-sifat terpuji, sebagaimana diuraikan di atas. Kemudian, kontekstualisasi dari pengajian ini diharapkan bisa menjadi rem agar manusia tidak terfokus untuk mencari dunia semata, tetapi tetap ingat bahwa dunia ini hanya persinggahan sementara, sehingga manusia senantiasa tidak keluar dari jalur-jalur syari’at yang ditetapkan oleh Allah dan Rasulny
A Risk Management Approach for Portfolio Insurance Strategies
No full textControlling and managing potential losses is one of the main objectives of the Risk Management. Following Ben Ameur and Prigent (2007) and Chen et al. (2008), and extending the first results by Hamidi et al. (2009) when adopting a risk management approach for defining insurance portfolio strategies, we analyze and illustrate a specific dynamic portfolio insurance strategy depending on the Value-at-Risk level of the covered portfolio on the French stock market. This dynamic approach is derived from the traditional and popular portfolio insurance strategy (Cf. Black and Jones, 1987 ; Black and Perold, 1992) : the so-called "Constant Proportion Portfolio Insurance" (CPPI). However, financial results produced by this strategy crucially depend upon the leverage - called the multiple - likely guaranteeing a predetermined floor value whatever the plausible market evolutions. In other words, the unconditional multiple is defined once and for all in the traditional setting. The aim of this article is to further examine an alternative to the standard CPPI method, based on the determination of a conditional multiple. In this time-varying framework, the multiple is conditionally determined in order to remain the risk exposure constant, even if it also depends upon market conditions. Furthermore, we propose to define the multiple as a function of an extended Dynamic AutoRegressive Quantile model of the Value-at-Risk (DARQ-VaR). Using a French daily stock database (CAC 40) and individual stocks in the period 1998-2008), we present the main performance and risk results of the proposed Dynamic Proportion Portfolio Insurance strategy, first on real market data and secondly on artificial bootstrapped and surrogate data. Our main conclusion strengthens the previous ones : the conditional Dynamic Strategy with Constant-risk exposure dominates most of the time the traditional Constant-asset exposure unconditional strategies.CPPI, Portfolio insurance, VaR, CAViaR, quantile regression, dynamic quantile model.
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