A novel symmetric/asymmetric multilevel current source inverter topology with lower number of components and lowest power rating of switches

A novel multilevel current source inverter (MCSI) configuration is introduced in this paper. The ability of handling with asymmetrical DC sources is one of the substantial advantages of the proposed inverter. In asymmetric mode, by appropriate selection of DC sources magnitude, a considerable increase can be obtained in the number of output levels without any manipulation on inverters’ hardware. In MCSIs, the number of required circuit devices is very important because the overall costs, circuit size, reliability and control complexity are dependent on them directly. The proposed inverter can generate all desired current levels using a lower number of elements. Besides, it is known that reduction of number of switches from conventional inverters imposes an undesired increase in total semiconductor device power (SDP). But, the total SDP of the proposed inverter is kept equal to conventional inverter. To validate the superiority of the proposed inverter, a full comparison is provided. Also, the computer simulation and experimental results are presented.     

The Artless Word: Mies van der Rohe on the Building Art

Abstract

The project was the first-place winner of a design-build competition initiated by the Student Forum at The Harvard Design School. Faculty and students served on the jury for the competition. Students were challenged to design a new mail-slot system for 320 students with removable name labels. The competition offered students an opportunity to realize a project and, through that process, explore and learn about design, material properties, fabrication, and construction techniques. The resulting proposal is a new piece of informational infrastructure that engages the physical and digital transfer of information.     

Surface: A-Tectonic of Roofing and Wrapping

This paper makes the claim that a different understanding of architecture prevails when criticism aims at exploring the threshold between theory and architectural autonomy. To navigate in the realm of theory, and to lend form merely to the vicissitudes of cultural theories, dismisses both history andarchitecture's position in the capitalist cycle of production and consumption. This paperer attempts to historicize contemporary architecture in reference to Gottfried Semper s theory of dressing. The intention is to demonstrate that proliferation of the tectonic rapport between the two elements of roof and clothing is informed by the conflation of architecture's interiority with digital techniques. Semper is important today because his idea of theatricality provides a useful tool for analysing the expressionistic tendencies of computer-generated forms, and the latter's relation to the aesthetics of commodity fetishism. Once a semi-autonomous understanding of architecture is established, an argument can be made to plot two recent projects by Peter Eisenman and Renzo Piano in the context of what might be called topological tectonics. The binary underpinning of this comparison is prohlematized when Greg Lynn's views on the tectonics of blob are included in the fuzzy picture of current architectural theories.     

Kenneth Frampton,David Malouf and Juhani Pallasma,Glenn Murcutt,Architect

This article uses Christmas Island as a site to discuss the contested history of Australian immigration in terms of the built environment. Offshore detention centres and the political systems for detaining asylum seekers pose substantial demands of institutional design, control of populations, and psychic anxieties associated with the arrival of foreigners. Systems of detention are explored through the topics of territory, human labour, boats as visual signs, and the buildings constructed to house detainees. Entangled orders of security expose detention as a timely subject for architectural intervention and commentary.     

Reconfiguration and DG Sizing and Placement Using Improved Shuffled Frog Leaping Algorithm

Abstract

In this paper is proposed a reconfiguration methodology with the presence of Distributed Generation (DG), aimed at achieving the minimum power loss, minimum number of switching operation and minimum deviation of bus voltage while satisfying all constraints using improved shuffled frog leaping algorithm (ISFLA).The performance of the proposed method is examined on 33 and 69 bus IEEE test distribution systems. The ISFLA performance is evaluated with the well-known algorithm including of harmony search algorithm (HSA), refined genetic algorithm (GRA), particle swarm optimization (PSO), differential evolutionary (DE) and conventional SFLA. Simulation results showed that the total power loss and voltage bus minimum in primary distribution network can be reduced significantly. Also the results in different scenarios are showed that the simultaneous reconfiguration and DG placement method is better in less losses and also in more minimum voltage. Moreover, the ISFLA superiority is proved in comparison with the HAS, GRA, PSO, DE, and SFLA in view of more convergence speed and accuracy and also converges in less number iteration. Also, the performance of the proposed method is favorable compared to previous studies.     

Hot Expansion of a Thin-Walled Cylindrical Shell of Porous Material

A system of equations describing the hot expansion of a thin-walled cylindrical shell of porous material by internal pressure was obtained. The solution was based on one of the simplest creep theories, namely, work hardening theory. The radial, meridial, and volume rates of creep deformation were calculated in comparison with the basic circumferential deformation rate of the shell. The numerical results were obtained by considering a process of stepwise loading of the shell. It was established that porosity in the material decreases the limiting value of internal pressure of the shell.     

Sensitivity Analysis on Ladder Network Equivalent Circuit Parameters of Power Transformer

In this article, novel methods and ideas are introduced, which altogether lead to an accurate model of power transformer windings. First, by the determination of non-dominant (hidden) resonances from frequency-response tests, a ladder model is proposed. Next, it is improved by assigning different values for similar elements of each section of the model. The parameters are obtained by minimizing the error function via a genetic algorithm. Sensitivity analysis is then applied to the obtained model to achieve further examinations and tests. Measurements have been driven from the windings of a 20/0.4-kV, 1600-kVA transformer. Modeling, methodologies, and sensitivity analysis in this article can be very useful for future research aiming to find internal faults of the transformer with the frequency response analysis.     

A zero-current switching switched-capacitor DC-DC converter with reduction in cost,complexity, and size

This paper presents a new step-up switched-capacitor (SC) DC-DC converter which has many advantages such as reduction in investment cost, control complexity, number of components, voltage stress on components, and size over traditional topologies. In the proposed structure, power switches are reduced in number which in turn leads to the merits mentioned earlier and makes the converter more suitable for industrial applications. Furthermore, a previously introduced zero-current switching (ZCS) method is used here which provides soft switching for the devices. There is also a reduction in the number of required inductors to achieve ZCS due to the decreased number of switches in the proposed converter. The proposed converter is validated by comprehensive simulation results in MATLAB Simulink environment and also precise experimental results which show the acceptable performance of the proposed topology.     

Test System for Detailed Model of Transformers for Transient Analysis Using the Electromagnetic Transient Program (EMTP)

This paper describes a detailed model of a transformer designed to evaluate the ability of winding insulation to withstand transients. The time domain electromagnetic transient program (EMTP) was used to develop a model of the transient characteristics of the winding. It is difficult for students to use EMTP and understand simulation results. This paper contains all the data needed to develop a detailed model for transient analysis and presents basic case studies and alternative design/operating configurations.     

The Project of Modernity: Can Architecture Make It?

The title of this essay suggests that architecture's relation to modernity is a complex one. What needs to be discussed is the specificity of architecture's conflict with modernity. While historical analysis theorizes socio-cultural and political phenomena, the thematic of architecture's entanglement with capitalism necessitates an argument, addressing the dialogical relationship between theory and practice. Historical analysis is one thing; mobilization of history to change the present situation is another. This much is clear from the discourse of thinkers who are associated with ‘critical theory,’ and the work of architectural historian Manfredo Tafuri, among others.

This essay attempts to read Tafuri's Architecture and Utopia: Design and Capitalist Development, translated into English in 1976,¹ in the context of current critical theories and to demonstrate the relevance of his argument today. To be more specific, the intention is to approach Tafuri's text from the argument presented in the first chapter of Susan Buck-Morss's Dreamworld and Catastrophe.² The author re-writes the interaction between the early modern states and avant-garde artists in reference to space and time. Her paradigm suspends the idea of Zeitgeist and shows how space (territory) was the subject matter of an idea of progress that was imagined by both capitalist and socialist states of the 1930s. Secondly, Buck-Morss discusses the ways architecture occasionally went out-of-time in the historical cosmology, formulated by the forces of modernization that were unravelling during the early decades of the last century. Her discourse provides a system of periodization that surpasses historicism. Tafuri's vision of history also questions historicism,³ but if read in the light of Buck-Morss's discourse, one can see ideas in Tafuri which are perhaps more relevant to architecture's situation today than when they were written.