Plaquette operators used in the rigorous study of ground-states of the Periodic Anderson Model in D=2D = 2 dimensions

The derivation procedure of exact ground-states for the periodic Anderson model (PAM) in restricted regions of the parameter space and D=2 dimensions using plaquette operators is presented in detail. Using this procedure, we are reporting for the first time exact ground-states for PAM in 2D and finite value of the interaction, whose presence do not require the next to nearest neighbor extension terms in the Hamiltonian. In order to do this, a completely new type of plaquette operator is introduced for PAM, based on which a new localized phase is deduced whose physical properties are analyzed in detail. The obtained results provide exact theoretical data which can be used for the understanding of system properties leading to metal-insulator transitions, strongly debated in recent publications in the frame of PAM. In the described case, the lost of the localization character is connected to the break-down of the long-range density-density correlations rather than Kondo physics.Comment: 34 pages, 5 figure

Is diversity good?

Prominent ethical and policy issues such as affirmative action and female enrollment in science and engineering revolve around the idea that diversity is good. However, even though diversity is an ambiguous concept, a precise definition is seldom provided. We show that diversity may be construed as a factual description, a craving for symmetry, an intrinsic good, an instrumental good, a symptom, or a side effect. These acceptions differ vastly in their nature and properties. The first one cannot lead to any action and the second one is mistaken. Diversity as intrinsic good is a mere opinion, which cannot be concretely applied; moreover, the most commonly invoked forms of diversity (sexual and racial) are not intrinsically good. On the other hand, diversity as instrumental good can be evaluated empirically and can give rise to policies, but these may be very weak. Finally, symptoms and side effects are not actually about diversity. We consider the example of female enrollment in science and engineering, interpreting the various arguments found in the literature in light of this polysemy. Keywords: ethics, policy, higher education, female students, minority students, affirmative actionComment: 7 page

Books on power transformers in English - Part 2

In this second part of the column about the books on power transformers, we explore two books from the early 1900s. Those are The Alternating Current Transformer by Frank George Baum, published in 1903, and Transformer Practice, Manufacture, Assembling, Connections, Operation and Testing by William T. Taylor, published in 1909. These exciting books are a testament to the historical development of transformer technology

Books on power transformers in English - Part 3

Parts 1 and 2 of this series covered transformer books published until 1909. This part covers a transformer book published in the first decade of the twentieth century. In 1909, Alfred H. Avery published a landmark book on autotransformers, laying the groundwork for future advancements in electrical engineering. This article reviews the book’s contributions to solving early electrical distribution problems and enhancing lighting efficiency. It also explores the subsequent evolution of autotransformers, emphasizing their role in meeting modern energy demands

Books on power transformers in Russian – A bibliography 1969 – 2017

The bibliography of Russian books on power transformers and reactors is a continuation of the bibliography of books on power transformers in Germans published earlier. It was compiled at accessible Internet addresses for a period from 1924 (F. I. Kholuyanov, Single-phase, and three-phase transformers, 1924 - the first Russian book on transformers) until April 2020. The purpose of the compilation of published books is to give a historical resume on the topic, which may also be useful to other specialists in their research

Books on power transformers in Russian – A bibliography 1924 – 1969

The bibliography of Russian books on power transformers and reactors is a continuation of the bibliography of books on power transformers in the German language, published earlier. It was compiled at accessible Internet addresses for a period from 1924 (F. I. Kholuyanov, Single-phase and three-phase transformers, 1924 - the first Russian book on transformers) until April 2020. The purpose of the compilation of published books is to give a historical resume on the topic, which may also be useful to other specialists in their research. Part I of this compilation covers the period from 1924 until 1969

Books on power transformers in Russian – A bibliography 1924 – 1969

The bibliography of Russian books on power transformers and reactors is a continuation of the bibliography of books on power transformers in the German language, published earlier. It was compiled at accessible Internet addresses for a period from 1924 (F. I. Kholuyanov, Single-phase and three-phase transformers, 1924 - the first Russian book on transformers) until April 2020. The purpose of the compilation of published books is to give a historical resume on the topic, which may also be useful to other specialists in their research. Part I of this compilation covers the period from 1924 until 1969

Books on power transformers in Russian IV

We present to you this last part of the bibliography of Russian books on power transformers. It is dedicated to reactors, special transformers and related to transformer engineering for the period 1980–April 2020. It also has a section on Russian transformer books translated into English