Transmission Line Circuit Models for Dielectric Waveguide     

Herbert J. Carlin  Pier Paolo Civalleri  Jeffrey C. Hantgan 《Journal of The Franklin Institute》1981,311(4):209-230

A general procedure is outlined for obtaining single or coupled transmission line models to represent the propagation of surface wave modes in conductively unshielded dielectric waveguides. The procedure uses a homogeneous electrically or magnetically walled waveguide having the same dimensions as the dielectric of the surface waveguide, to produce a set of orthogonal eigenfunctions. These eigenfunctions are projected upon Maxwell's equations resulting in a system of transmission lines coupled together through a wave immittance, which represents the ratio of a longitudinal and a transverse field component at the dielectric-air interface. Examples are given for various modes of the dielectric slab and the dielectric rod, in particular the HE_1n modes for the latter. The transmission line models derived for these examples consist of a single trasmission line found directly by projection or reduced from a coupled transmission line model by port elimination, or of two transmission lines coupled together. All circuit models derived preserve the basic properties of surface waves (e.g. no solution below cut-off), and any of the single line models can be solved to give explicit approximate algebraic formulae for the propagation constant as a function of frequency. Numerical results show that the dispersion curves calculated from the models versus exact values are generally excellent over the entire frequency spectrum.  相似文献   

The tragedy of the digital commons   总被引：1，自引：0，他引：1  

Gian Maria Greco  Luciano Floridi 《Ethics and Information Technology》2004,6(2):73-81

In the paper it is argued that bridging the digital divide may cause a new ethical and social dilemma. Using Hardin's Tragedy of the Commons, we show that an improper opening and enlargement of the digital environment (Infosphere) is likely to produce a Tragedy of the Digital Commons (TDC). In the course of the analysis, we explain why Adar and Huberman's previous use of Hardin's Tragedy to interpret certain recent phenomena in the Infosphere (especially peer-to-peer communication) may not be entirely satisfactory. We then seek to provide an improved version of the TDC that avoids the possible shortcomings of their model. Next, we analyse some problems encountered by the application of classical ethics in the resolution of the TDC. In the conclusion, we outline the kind of work that will be required to develop an ethical approach that may bridge the digital divide but avoid the TDC.  相似文献   

Combination of a Liquid-Dispensing and Micro-Aspiration Device for the Cleaning of Sensitive Painted Surfaces     

Paolo Cremonesi 《文物保护研究》2018,63(6):315-325

Many painted surfaces, not necessarily only those with a contemporary binding media, display high sensitivity to water. The resulting damage, including swelling, leaching out of some components, even partial solubility, may lead to a shrunken, impoverished, de-plasticized, more porous paint film. Different approaches to the cleaning of such surfaces have been developed throughout the years, as awareness of this sensitivity grew worldwide. Some deal with the proper physico-chemical conditions of the aqueous solutions, and others with the proper ways of delivering these solutions to the surface. The strategy proposed in this technical note is concerned with the latter, the application stage, and is based on the combined and simultaneous use of a device capable of delivering a constant, precise amount of the aqueous cleaning solution and a surgical micro-aspirator to immediately remove the soiled solution from the surface and speed up its drying. Also, using a different apparatus, non-polar solvents can be delivered, for cleaning surfaces contaminated by non-polar, more lipophilic soiling materials.  相似文献   

On cross-lingual retrieval with multilingual text encoders     

Litschko  Robert  Vulić  Ivan  Ponzetto  Simone Paolo  Glavaš  Goran 《Information Retrieval》2022,25(2):149-183

Information Retrieval Journal - Pretrained multilingual text encoders based on neural transformer architectures, such as multilingual BERT (mBERT) and XLM, have recently become a default paradigm...  相似文献   

Cultural analysis of mathematical content in teacher education: the case of Elementary Arithmetic Theorems     

Elda Guala  Paolo Boero 《Educational Studies in Mathematics》2017,96(2):207-227

This paper deals with the competence of Cultural (epistemological, historical and anthropological) Analysis of the Content (CAC), which is important for teachers’ awareness and autonomy when dealing with educational choices in a changing cultural and institutional context. We report on an 18-hour intervention in a teacher education course at the undergraduate level attended by 12 participants during the fall of 2013. The goal of the intervention was to enhance participants’ CAC in the case of Elementary Arithmetic Theorems by using the rationality construct derived from Habermas’ work. Qualitative analyses of participants’ discussions showed how the construct was gradually appropriated by them and contributed to their CAC. Trends emerging from quantitative comparisons with previous implementations of the same course provided some evidence regarding the effects of the intervention on the quality of participants’ CAC performances at the end of the course. The method chosen for participants’ assessment and their cultural background will be discussed as conditions for the success of the intervention.  相似文献   

Inter-letter spacing,inter-word spacing,and font with dyslexia-friendly features: testing text readability in people with and without dyslexia     

Jessica Galliussi  Luciano Perondi  Giuseppe Chia  Walter Gerbino  Paolo Bernardis 《Annals of dyslexia》2020,70(1):141-152

Over the last years, several studies have suggested a possible link between dyslexia and deficits in low-level visual processing (e.g., excessive crowding). At the same time, specially designed “dyslexia-friendly” fonts appeared on the market. This class of fonts presents two main features: the particular graphic characteristics of the letterform designed to avoid confusion between similarly shaped letters, and wider inter-letter and inter-word spacing to limit crowding. The literature testing the efficacy of “dyslexia-friendly” fonts in improving reading accuracy and increasing reading speed is controversial. We evaluated the impact of letterform (with vs. without dyslexia-friendly graphic features), inter-letter spacing (standard vs. increased), and inter-word spacing (standard vs. increased) on reading accuracy and speed. Two groups of 64 children each, with and without dyslexia, read aloud 8 equivalent texts. The data collected failed to show any effect from the letterform. As regards spacing, the data showed that reading speed is impaired by an increase in inter-letter spacing not combined with an adequate increase in inter-word spacing.  相似文献   

The influence of reading literacy on mathematics and science achievement     

Elisa Caponera  Paolo Sestito  Paolo M. Russo 《The Journal of educational research》2016,109(2):197-204

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Detecting ethnicity-targeted hate speech in Russian social media texts     

Ekaterina Pronoza  Polina Panicheva  Olessia Koltsova  Paolo Rosso 《Information processing & management》2021,58(6):102674

Ethnicity-targeted hate speech has been widely shown to influence on-the-ground inter-ethnic conflict and violence, especially in such multi-ethnic societies as Russia. Therefore, ethnicity-targeted hate speech detection in user texts is becoming an important task. However, it faces a number of unresolved problems: difficulties of reliable mark-up, informal and indirect ways of expressing negativity in user texts (such as irony, false generalization and attribution of unfavored actions to targeted groups), users’ inclination to express opposite attitudes to different ethnic groups in the same text and, finally, lack of research on languages other than English. In this work we address several of these problems in the task of ethnicity-targeted hate speech detection in Russian-language social media texts. This approach allows us to differentiate between attitudes towards different ethnic groups mentioned in the same text – a task that has never been addressed before. We use a dataset of over 2,6M user messages mentioning ethnic groups to construct a representative sample of 12K instances (ethnic group, text) that are further thoroughly annotated via a special procedure. In contrast to many previous collections that usually comprise extreme cases of toxic speech, representativity of our sample secures a realistic and, therefore, much higher proportion of subtle negativity which additionally complicates its automatic detection. We then experiment with four types of machine learning models, from traditional classifiers such as SVM to deep learning approaches, notably the recently introduced BERT architecture, and interpret their predictions in terms of various linguistic phenomena. In addition to hate speech detection with a text-level two-class approach (hate, no hate), we also justify and implement a unique instance-based three-class approach (positive, neutral, negative attitude, the latter implying hate speech). Our best results are achieved by using fine-tuned and pre-trained RuBERT combined with linguistic features, with F1-hate=0.760, F1-macro=0.833 on the text-level two-class problem comparable to previous studies, and F1-hate=0.813, F1-macro=0.824 on our unique instance-based three-class hate speech detection task. Finally, we perform error analysis, and it reveals that further improvement could be achieved by accounting for complex and creative language issues more accurately, i.e., by detecting irony and unconventional forms of obscene lexicon.  相似文献   

Irony detection via sentiment-based transfer learning     

Shiwei Zhang  Xiuzhen Zhang  Jeffrey Chan  Paolo Rosso 《Information processing & management》2019,56(5):1633-1644

Irony as a literary technique is widely used in online texts such as Twitter posts. Accurate irony detection is crucial for tasks such as effective sentiment analysis. A text’s ironic intent is defined by its context incongruity. For example in the phrase “I love being ignored”, the irony is defined by the incongruity between the positive word “love” and the negative context of “being ignored”. Existing studies mostly formulate irony detection as a standard supervised learning text categorization task, relying on explicit expressions for detecting context incongruity. In this paper we formulate irony detection instead as a transfer learning task where supervised learning on irony labeled text is enriched with knowledge transferred from external sentiment analysis resources. Importantly, we focus on identifying the hidden, implicit incongruity without relying on explicit incongruity expressions, as in “I like to think of myself as a broken down Justin Bieber – my philosophy professor.” We propose three transfer learning-based approaches to using sentiment knowledge to improve the attention mechanism of recurrent neural models for capturing hidden patterns for incongruity. Our main findings are: (1) Using sentiment knowledge from external resources is a very effective approach to improving irony detection; (2) For detecting implicit incongruity, transferring deep sentiment features seems to be the most effective way. Experiments show that our proposed models outperform state-of-the-art neural models for irony detection.  相似文献   

Universities’ attractiveness to students: The Darwinism effect     

Mattia Cattaneo  Hugo Horta  Paolo Malighetti  Michele Meoli  Stefano Paleari 《Higher Education Quarterly》2019,73(1):85-99

Due to significant government cuts to Higher Education funding in Southern European systems, their already underfunded universities were forced to increasingly compete for students as sources of additional revenue. Concurrently, families and students that continued to afford participation in Higher Education became more selective when choosing a university, realising the riskier investment that Higher Education participation had become. Through a competing destinations model and relying on all Italian private and public universities, this study finds that the competition forces characterising universities’ attractiveness over the last decade have changed since the financial crisis of 2008. In a context of lower demand for Higher Education, the competition for students grew and universities in close proximity were better prepared to face the new challenges, leading to the growth of Higher Education clusters.  相似文献