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This paper aims to improve the finite element modelling of transformers subjected to DC excitation, by including core joint details.

Geomagnetically induced currents (GICs) or leakage DC can cause part-cycle, half wave saturation of a power transformer’s core. Practical measurements and finite element matrix (FEM) simulation were carried out using three laboratory-scale, untanked single-phase four limb transformers resembling real power transformers in terms of the core steel and parallel winding assemblies. “Equivalent air gaps” at the joints, based on AC measurements, were applied to the FEM models for simultaneous AC and DC excitation.

Measurements confirm that introducing equivalent air gaps at the joints improves the FEM simulation of transformers carrying DC.

The FEM simulations based on the laboratory transformers are exemplary, showing the difference between modelling core joints as solid or including equivalent air gaps. They show that, for more representative results, laboratory transformers used for research should have mitred core joints (like power transformers).

This research shows why joint details are important in FEM models for analysing transformer core saturation in the presence of DC/GICs. Extending this, other core structures of power transformers with mitred joints should improve the understanding of the leakage flux during half-wave saturation.

The purpose of this paper is to present a simple method to analyze the iron loss in the laminated core of power and distribution transformers.

This paper presents a practical method to calculate the no-load loss in the transformer cores. Considering the non-uniformity of the magnetic flux density in the corner areas of the Epstein frames will affect the measurement precision of the Wt-B curves then further affect the core loss calculation in FEM, a dual-Epstein frame method is used to measure the Wt-B curves with the Epstein sample stripes cutting by different angles to the rolling direction. A 2D FEM that considers the type of joints of the core and eddy current effect in the laminations is used to analyze the core loss with multi-angle Wt-B curves.

The impact of lamination thickness, size of gaps and type of joint of the core are considered. Considering the no-load testing conditions, harmonics in the exciting currents are taken into account.

Harmonic wave of magnetic flux density in the transformer core is calculated and the core loss in the joint region is calculated by the loss curve measured with dual-Epstein frame. It makes the calculation result of transformer core loss more exactly.

Magnetic properties of step‐lap joints have been investigated experimentally on scale‐models of a three‐phase three‐leg transformer core. The influence of core induction, number of steps and overlapping length has been investigated.

This paper aims to investigate the impact of combining grain-oriented electrical steel (GOES) grades on specific iron losses and the flux density distribution within a single-phase magnetic core.

This paper presents the results of finite-element method (FEM) simulations investigating the impact of mixing two different GOES grades on losses of a single-phase magnetic core. The authors used different models: a 3D model with a highly detailed geometry including both saturation and anisotropy, as well as a simplified 2D model to save computation time. The behavior of the flux distribution in the mixed magnetic core is analyzed. Finally, the results from the numerical simulations are compared with experimental results.

The specific iron losses of a mixed magnetic core exhibit a nonlinear decrease with respect to the GOES grade with the lowest losses. Analyzing the magnetic core behavior using 2D and 3D FEM shows that the rolling direction of the GOES grades plays a critical role on the nonlinearity variation of the specific losses.

The novelty of this research lies in achieving an optimum trade-off between the manufacturing cost and the core efficiency by combining conventional and high-performance GOES grade in a single-phase magnetic core.

The influence of overlap joints in transformer cores on the local flux and eddy current distribution and on overall transformer characteristics is studied by means of two‐dimensional finite element (2D FE) models. A simplified 2D FE model of a single overlap joint is used for estimating the resulting increased magnetomotive force and increased eddy current losses. Both effects can be accounted for in a 2D FE model of the complete transformer by locally adopting modified material characteristics (viz. BH‐curve and electrical conductivity) in the cross‐section of the core. This novel method is demonstrated and validated by applying it to a three phase transformer. The calculated no‐load currents and losses are compared to the measured ones.

Mutual Investigation. There seems to be a refreshing, open breeze blowing through the ranks of time and motion study technicians these days. Gone are the ponderous exponents of the mystic art and, instead, we find the experts vying with each other, almost, in telling their audiences how easy time and motion study really is if you only sit down and think about it.

AIRCRAFT structural engineers have long been intrigued by the possibility of eliminating the thousands of assembly operations involved in a typical airframe structure—one composed of many formed pieces joined by rivets and bolts—and of replacing these multiple operations with a double, or even a single, automatic operation employing simply temperature and pressure.

Defects can be caused by a number of factors, such as maintenance damage, ground handling and foreign objects thrown up from runways during an in-service use of composite aerospace structures. Sandwich structures are capable of absorbing large amounts of energy under impact loads, resulting in high structural crashworthiness. This situation is one of the many reasons why sandwich structures are extensively used in many aerospace applications nowadays. Their non-destructive inspection is often more complex. Hence, the choice of a suitable non-destructive testing (NDT) method can play a key role in successful damage detection. The paper aims to discuss these issues.

A comparison of detection capabilities of selected C-scan NDT methods applicable for inspections of sandwich structures was performed using water-squirt, air-coupled and pitch-catch (PC) ultrasonic techniques, supplemented by laser shearography (LS).

Test results showed that the water-squirt and PC techniques are the most suitable methods for core damage evaluation. Meanwhile, the air-coupled method showed lower sensitivity for the detection of several artificial defects and impact damage in honeycomb sandwiches when unfocussed transducers were used. LS can detect most of the defects in the panels, but it has lower sensitivity and resolution for honeycomb core-type sandwiches.

This study quantitatively compared the damage size indication capabilities of sandwich structures by using various NDT techniques. Results of the realised tests can be used for successful selection of a suitable NDT method. Combinations of the presented methods revealed most defects.

Rapid urbanization and providing pragmatic solutions for its development is one of the fundamental agenda of last decade. The metabolism is one of the latest post-war movements-founded in 1960 by Kenzo Tange where urbanization and city as a process is re-examined within the framework of accelerated modernism and technology vision. This paper discusses Metabolism movement in order to identify crucial intimations of its utopian architectural and urban approaches as a tool for future city. The study examines four initial metabolist city approaches-Plan for Tokyo (1960-62), Clusters/city in the Air (1960-62), Helix city (1961) and Ocean/Marine City (1962) that are designed for post-war Tokyo city in Japan. The study gives modest insight of indentifying city design theory within in a series conception; such as conducting to architectural characteristics regarding urban structure, tectonic vision between land-sea-sky and organic notion (city as process and mega-structuralism). Research method is embodied with examining relevant data of literature data. Upon discussions on theory, study aims to establish an ironic notion of future city by asserting familiar characteristics or variations between four pioneer projects of Metabolist movement.

This paper aims to describe how knowledge management (KM) in planning can support the sustainability of innovation in a hybrid, joint-use facility. The case study research studies ImaginOn, a 15 year-old children’s library and theater for young people in Charlotte, NC.

This research used KM model analysis of qualitative data about tacit-explicit knowledge, intellectual capital (IC) and cognitive modes of collaboration. Both historic documents and primary data (from field study observations, interviews and a questionnaire) were analyzed for informal KM practices. Semi-structured and unstructured interview questions about innovation were used.

This study found evidence of tacit knowledge sharing, the growth of IC and the operationalization of collaboration to promote innovation. Although traditional KM terms were not used by staff, an integrated model framework demonstrates how KM practices promote innovation in planning joint-use facilities.

Although a study of a diverse cultural collaboration rather than two libraries, the KM practices that supported innovation and collaboration in this hybrid, joint-use facility might be applied to libraries. Future KM model research on joint-use organizations could investigate merged businesses, government programs and non-profits.

The library and theater institutions in ImaginOn impact the lives of children and parents in meaningful ways that support community understanding, art, diversity and social interaction.

Research on joint-use libraries began in the 1960s. This case study provides unique model analysis of KM practices in a hybrid, joint-use facility (a library and theater). The innovative success and sustainability of ImaginOn illustrates the application of KM for strategic planning and aligning IC and business assets.