2,953 research outputs found


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    This study aims to determine the application of the Public Information Disclosure Policy at the Department of Communication, Informatics and Statistics, Enrekang Regency. This type of research uses a qualitative method which aims to provide a descriptive description of the application of the Public Information Disclosure Policy at the Department of Communication, Information and Statistics, Enrekang Regency. Data sources consist of primary data obtained through interviews, and secondary data taken from documents, records, reports, and official archives that can be supported by the integrity of primary data. The results of the study indicate that the communication indicator produces answers that are in accordance with existing policies, the second indicator regarding resources shows that it is good, and the third disposition shows that the results are already responsible for its implementation

    Optimisation of Magnetic Circuit for Brushless Doubly Fed Machines

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    This paper presents an optimized design method for the magnetic circuit of brushless doubly fed machines (BDFMs). The BDFM is an attractive electrical machine, particularly for wind power applications, as a replacement for doubly fed slip-ring generators. This study shows that the conventional design methods for the BDFM stator and rotor back iron can be modified, leading to a lighter and smaller machine. The proposed design concepts are supported by analytical methods, and their practicality is verified using two-dimensional finite-element modeling and analysis. Two BDFMs with frame sizes D180 and D400 are considered in this study

    Equivalent Circuit Parameters for Large Brushless Doubly Fed Machines (BDFM)

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    This paper presents analytical methods to calculate the equivalent circuit parameters for large-scale brushless doubly fed machines (BDFMs) with magnetic wedges utilized for closing stator open slots. The use of magnetic wedges reduces the magnetizing currents in the machine, reflected in the values of magnetizing inductances, but also increases leakage fluxes affecting the value of series inductances in the equivalent circuit. Though such effects can be modeled by numerical models, the proposed analytical methods are particularly helpful in optimizing machine design, inverter rating, reactive power management, and grid low-voltage ride-through performance. The conventional analytical methods cannot be readily applied to the BDFM due to its complex magnetic field distribution; this paper presents analytical methods to calculate the magnetizing and leakage inductances for the BDFM with magnetic wedges used in the stator slots. The proposed methods are assessed by experimentally verified finite-element models for a 250 kW BDFM

    Islam and (Political) Liberalism: a Note on an Evolving Debate in Indonesia

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    This paper is divided into three parts. The first part will provide a general overview of some major approaches in the discussion on the relationship between Islam and liberalism. Following this, the next section will briefly elaborate Talal Asad\u27s notion of Islam as ‘a discursive tradition\u27 and John Rawls\u27 distinction between liberalism and political liberalism and how they might contribute to the discussion on the relationship between Islam and liberalism. In the final part, the paper will then present a general observation on the evolving encounter between Islam and liberalism in Indonesia and the accompanying debate over this encounter among major Islamic groups in the country. In doing so, it will be argued that while liberalism as a comprehensive doctrine has been, and will remain, contested among Indonesan Muslims, there has been a growing support among them for ‘political liberalism\u27, although not in a purely Ralwsian sense

    Investigation of magnetic wedge effects in large-scale BDFMs

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    This paper studies the effects of magnetic wedges on the equivalent circuit parameters of the Brushless Doubly-Fed Machine (BDFM). Magnetic wedges are used in slot openings of large electrical machines to reduce magnetizing currents, but the study of their effects on the BDFM performance is not straightforward due to the complex magnetic fields in the BDFM. Equivalent circuit and FE models have been developed for a 250 kW BDFM taking into account the effects of wedges and verified experimentally

    Alternative to chromium, a hard alloy powder NiCrBCSi (Fe) coatings thermally sprayed on 60CrMn4 steel. Phase and comportements

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    AbstractThe purpose of this study was to investigate and to compare microstructural properties, wear resistance, and potentials of thermal spraying of NiCrBSiCFe coatings for a possible replacement of hard chromium plating in mechanical parts repair. The coatings surfaces and cross section were characterized before and after testing behavior using a scanning electron microscopy (SEM) coupled with an analyzer (EDAX). The characterization of phases was carried out by electron microprobe and X-ray diffraction. A good adherence of coating NiCrBCSi (Fe) on steel substrate is explained by formation of large diffusion zone in interface after annealing and by the nature of the structure deposit duplexes. This is explained by the split structure that we were able to characterize and which is composed of a phase lasts type boro carbide-nickel Ni3(BC) and the matrix based Nî reinforced by very fine rich Cr precipitates. These properties are enhanced by cyclic heat treatment

    Numerical evaluation of aerodynamic roughness of the built environment and complex terrain

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    Aerodynamic drag in the atmospheric boundary layer (ABL) is affected by the structure and density of obstacles (surface roughness) and nature of the terrain (topography). In building codes and standards, average roughness is usually determined somewhat subjectively by examination of aerial photographs. For detailed wind mapping, boundary layer wind tunnel (BLWT) testing is usually recommended. This may not be cost effective for many projects, in which case numerical studies become good alternatives. This thesis examines Computational Fluid Dynamics (CFD) for evaluation of aerodynamic roughness of the built environment and complex terrain. The present study started from development of an in-house CFD software tailored for ABL simulations. A three-dimensional finite-volume code was developed using flexible polyhedral elements as building blocks. The program is parallelized using MPI to run on clusters of processors so that micro-scale simulations can be conducted quickly. The program can also utilize the power of latest technology in high performance computing, namely GPUs. Various turbulence models including mixing-length, RANS, and LES models are implemented, and their suitability for ABL simulations assessed. Then the effect of surface roughness alone on wind profiles is assessed using CFD. Cases with various levels of complexity are considered including simplified models with roughness blocks of different arrangement, multiple roughness patches, semi-idealized urban model, and real built environment. Comparison with BLWT data for the first three cases showed good agreement thereby justifying explicit three-dimensional numerical approach. Due to lack of validation data, the real built environment case served only to demonstrate use of CFD for such purposes. Finally, the effect of topographic features on wind profiles was investigated using CFD. This work extends prior work done by the research team on multiple idealized two-dimensional topographic features to more elaborate three-dimensional simulations. It is found that two-dimensional simulations overestimate speed up over crests of hills and also show larger recirculation zones. The current study also emphasized turbulence characterization behind hills. Finally a real complex terrain case of the well-known Askervein hill was simulated and the results validated against published field observations. In general the results obtained from the current simulations compared well with those reported in literature

    Rotor parameter determination for the brushless doubly fed (induction) machine

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    A procedure has been established for obtaining equivalent circuit parameters for the Brushless Doubly Fed Machine (BDFM), also known as the Brushless Doubly Fed Induction Machine (DFIM), by transforming a reduced coupled-circuit model into a sequence component form. This approach takes advantage of the model reduction procedure’s ability to reduce a complex rotor structure to a single equivalent loop without significant loss of accuracy. An alternative method based on winding factors has also been developed and includes coupling via harmonic fields. Parameters determined in both ways are in close agreement with those determined from Finite Element Analysis (FEA) and experimentally. The advantages of each method is discussed in the conclusion section.This work was supported by the European Union's Seventh Framework Programme managed by REA – Research Executive Agency (FP7/2007_2013) under Grant Agreement N.315485.This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1049/iet-epa.2015.002
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