This paper presents a single-phase topology for multilevel inverters with minimum number of switching devices. The proposed topology significantly reduces the number of DC voltage sources, switches, and power diodes as the number of output voltage levels increases. The proposed multilevel inverter is constructed using series-connection of multilevel strings. Suggested multilevel string is composed of multiple basic switching units. The proposed multilevel inverter has Extendable configuration that increases the number of output voltage levels more and more by adding more stages. The proposed multilevel inverter would be implemented in both symmetric and asymmetric configurations. Two different algorithms are introduced for determination of magnitude of DC voltage sources to reach the maximum number of output voltage levels with minimum number of semiconductor devices. Important characteristics of both symmetric and asymmetric configurations are extracted and compared with similar multilevel inverter topologies. Finally, a prototype of the proposed multilevel inverter is simulated and implemented experimentally to verify operation of the proposed multilevel inverter.

The concept of Γ-semihyperrings is a generalization of a semiring, a generalization of a Γ-semiring, and a generalization of a semihyperering. In this paper, we define the notions of complex product, extension property and flat Γ-semihyperrings and some of their properties are obtained. In addition, we prove that every flat Γ-semihyperring is absolutely Extendable. Finally, we give some characterization of stable elements.

Islam spread rapidly after its founding, encompassing much of North Africa, the Middle East, and Southeast Asia. The art of this vast region draws its distinctive character both from Islam itself and from the diverse cultural traditions of the world’s Muslims. Because Islam discouraged the use of figurative images, particularly in religious contexts- unlike Christian art- Islamic artists developed a rich vocabulary of aniconic, or nonfigural, ornament that is a hallmark of Islamic work. This vocabulary includes complex geometric patterns and the scrolling vines known outside the Islamic world as arabesques. Figural representation, to the extent it was permitted which varied from time to time and place to place, first developed most prominently in regions with strong pre-Islamic figural traditions, such as those that had been under the control of the Roman and Byzantine empires. Stylized forms for representing animals and plants developed in the regions that had been under the control of the Sassanian dynasty of Persia (modern Iran), the heirs of the artistic traditions of the ancient Near East, who ruled from 226 to 641. Because the Arabian birthplace of Islam had little art, these Persian and Roman Byzantine influences shaped Islamic art in its formative centuries. The elements of early early Islamic architecture were formed to respond effectively to people’s physical, environmental, social, physiological and religious requirements at their time. The research demonstrates that architects used to copy-paste various elements of the Islamic historical buildings in their design work without understanding the meanings and values that it holds. Such approach would only transfer the element’s form though strips it from its historical context and values. The paper argues that architect should comprehend not only the hidden values of the historical elements only but also how values interacted and are integrated into these elements. By doing so, the architect would be able to correctly perceive and read these elements thus incorporate it successfully in his/ her design. This article gives perspective of early Islamic architecture and structural configurations of the related era.

Membrane Distillation (MD) is constantly acknowledged in the research literature as a promising technology for the future of desalination, with an increasing number of studies reported year after year. MD processes encompass various configurations designed for liquid separation applications. Four primary MD configurations are Direct Contact Membrane Distillation (DCMD), Air Gap Membrane Distillation (AGMD), Vacuum Membrane Distillation (VMD), and Sweeping Gas Membrane Distillation (SGMD). However, real MD applications still lag with only a few pilot-plant tests universal. The absence of technology transfer from academia to industry is caused by important gaps between its fundamental basis and the process design. MD has the potential to recover both chemicals and water. This review paper describes the background and properties of interest for desalination processes and reviews the recent literature for novel compounds used in membrane processes. The advantages and disadvantages of using particular methods, examples of applications, and integrated processes are pronounced. Perspectives, benefits, and limitations are also discussed.

Several studies on photovoltaic systems focused on how it operates and energy required in operating it. Little attention is paid on its configurations, modeling of mean time to system failure, availability, cost benefit and comparisons of parallel and series–parallel designs. In this research work, four system configurations were studied. Configuration I consists of two sub-components arranged in parallel with 24 V each, configuration II consists of four sub-components arranged logically in parallel with 12 V each, configuration III consists of four sub-components arranged in series–parallel with 8 V each, and configuration IV has six sub-components with 6 V each arranged in series–parallel. Comparative analysis was made using Chapman Kolmogorov’s method. The derivation for explicit expression of mean time to system failure, steady state availability and cost benefit analysis were performed, based on the comparison. Ranking method was used to determine the optimal configuration of the systems. The results of analytical and numerical solutions of system availability and mean time to system failure were determined and it was found that configuration I is the optimal configuration.