title: New results for battery impedance at very low frequencies

authors: Scott, Jonathan B.

subjects: Science & Technology

abstract: In search of an equivalent circuit model for rechargeable batteries, many authors start with a measurement of battery impedance, spanning what is presumed to be the frequency range of interest. Various networks have been suggested in the literature to account for the measured impedance characteristic. Most incorporate two or more resistors, at least one capacitor, some include at least one Warburg element, and more recently “constant phase elements”(CPE), otherwise identified as fractional-derivative capacitors. Networks that are more successful at reproducing the measured impedance have from five up to tens of degrees of freedom. The frequency range upon which most models are based extends only to 1mHz. This is surprising since many batteries see a daily or longer usage cycle, corresponding to a frequency of ≈ 11.6 μHz or lower. We show in this manuscript that the most-cited impedance measurement instrument, and one of the few that can operate below 1mHz, can be unreliable at and below this boundary. We present a novel impedance measurement algorithm robust against the issues present while measuring the impedance of electrochemical systems to as low as 1 μHz. Next, we present reliable impedance data extending to a lower frequency limit of 10 μHz. A remarkable characteristic appears at the lower frequencies, suggesting a surprisingly simple and elegant equivalent circuit consisting of a single fractional capacitor. A new model is proposed, which requires only four parameters to predict the measured impedance as a function of frequency.

text: New results for battery impedance at very low frequencies In search of an equivalent circuit model for rechargeable batteries, many authors start with a measurement of battery impedance, spanning what is presumed to be the frequency range of interest. Various networks have been suggested in the literature to account for the measured impedance characteristic. Most incorporate two or more resistors, at least one capacitor, some include at least one Warburg element, and more recently “constant phase elements”(CPE), otherwise identified as fractional-derivative capacitors. Networks that are more successful at reproducing the measured impedance have from five up to tens of degrees of freedom. The frequency range upon which most models are based extends only to 1mHz. This is surprising since many batteries see a daily or longer usage cycle, corresponding to a frequency of ≈ 11.6 μHz or lower. We show in this manuscript that the most-cited impedance measurement instrument, and one of the few that can operate below 1mHz, can be unreliable at and below this boundary. We present a novel impedance measurement algorithm robust against the issues present while measuring the impedance of electrochemical systems to as low as 1 μHz. Next, we present reliable impedance data extending to a lower frequency limit of 10 μHz. A remarkable characteristic appears at the lower frequencies, suggesting a surprisingly simple and elegant equivalent circuit consisting of a single fractional capacitor. A new model is proposed, which requires only four parameters to predict the measured impedance as a function of frequency.

year: 2019

title: Progger 3: A low-overhead, tamper-proof provenance system

authors: Corrick, Tristan James Carlile

subjects: Progger

abstract: Data provenance, which describes how data is accessed and used since the time it is created, is a valuable resource with a wide range of uses. It can be used simply to know who has accessed one's data, or be used in more complex scenarios such as detecting malware. One method for collecting data provenance is to observe system calls. This thesis presents Progger 3, a system that observes system calls on Linux in order to collect data provenance. There are several existing provenance systems that observe system calls, but they have limitations regarding security, efficiency, and usability. Progger 3 remedies many of these limitations. As a result, Progger 3 is a working implementation of a provenance system that can observe any system call, guarantee tamper-proof provenance collection as long as the kernel on the client is not compromised, and transfer the provenance to other systems with confidentiality and integrity, all with a relatively low performance overhead.

text: Progger 3: A low-overhead, tamper-proof provenance system Data provenance, which describes how data is accessed and used since the time it is created, is a valuable resource with a wide range of uses. It can be used simply to know who has accessed one's data, or be used in more complex scenarios such as detecting malware. One method for collecting data provenance is to observe system calls. This thesis presents Progger 3, a system that observes system calls on Linux in order to collect data provenance. There are several existing provenance systems that observe system calls, but they have limitations regarding security, efficiency, and usability. Progger 3 remedies many of these limitations. As a result, Progger 3 is a working implementation of a provenance system that can observe any system call, guarantee tamper-proof provenance collection as long as the kernel on the client is not compromised, and transfer the provenance to other systems with confidentiality and integrity, all with a relatively low performance overhead.

year: 2021

title: Lost in translation or lack of nuance? Perception of (near-)synonymy of common te reo Māori loanwords in New Zealand English

authors: Pohl, Alexander

abstract: Ongoing contact between languages and their speakers inevitably leads to a flow of words being borrowed from one language into another. Research in the field of language contact has established and documented the kinds of borrowed words that stick in their recipient language (Haspelmath 2009; Winford 2010). However, one question that has received comparatively less attention is how a newly adopted loanword relates to the structure of the existing lexicon it enters. In recent years, language contact research has thus seen a paradigm shift towards an onomasiological perspective (see Anderson et al. 2017; Crombez et al. 2022; Zenner et al. 2023). Within this approach, most studies looking at lexical variation between loanwords and their (near-)synonyms employ corpus linguistics methods (e.g. Onysko & Winter-Froemel 2011; Soares da Silva 2013). However, there is variation in how these corpus studies have investigated loanword meanings, and, to our knowledge, there has been almost no experimental research focussed specifically on the relationship between loanwords and their (near-)synonyms to date. This project presents a large-scale experimental approach from a case-study examining Māori loanwords borrowed into New Zealand English (NZE). NZE presents an unusual language contact situation because it involves a dominant language (NZE) receiving an exceptionally high amount of lexical material (words and phrases) from an Indigenous language: Māori. Further adding to the uniqueness of this contact situation is the fact that only a fraction of the population (<10%) speaks Māori fluently (Statistics New Zealand 2019). Nonetheless, Māori loanwords are ubiquitous, salient, and probably still increasing within the NZE lexicon (Macalister 2007; Trye et al. 2019). One important dimension of this set of borrowings are their semantic characteristics, which straddle three main classes of words: flora and fauna (mānuka ‘tea tree’), material culture (maunga ‘mountain’) and social culture (mana ‘power’).  Here, we report on a Qualtrics experiment devised to probe the perceived relationship between 60 Māori loanwords and their NZE equivalents, as ascertained from published sources. The synonymy judgements were elicited for pairs (e.g. whānau – family) using an analogue slider (ranging from 0 = non-synonymous to 100 = fully synonymous). Data was collected using a three-tiered questionnaire: 1) assessing synonymy of loanwords; 2) eliciting strategies for semantic assessments; and 3) collating background information about participants. Following cleaning and exclusions, the dataset showed a skew towards female participants, and for this reason, we focus our statistical analysis on the core sample containing (n = 170) young women (18-24 years). The results of the synonymy judgements analysis consist of qualitative inspections of box plots in relation to the semantic characteristics of Māori words in question, as well as sociodemographic variables of interest, specifically: years lived in Aotearoa NZ, and a composite score capturing exposure to and attitude towards Māori (TRMO). Preliminary findings suggest that many people think Māori loanwords are (highly) synonymous with NZE lexical alternatives. Our regression analyses exhibit evidence that years lived in Aotearoa NZ (p = 0.0054) and TRMO (p = 8.26e-10) can predict knowledge of Māori words. No statistically significant evidence was found for any predictors regarding the scores of the synonymy judgements; instead, we found that the random effects account for most of the variation. This is indicative of idiosyncratic loanword behaviour, in line with situations where variation is in-flux. These findings will be complemented by qualitative analyses of comments provided by participants in the open answer section (2). The talk will conclude with a summary of contributions to the general understanding of loanword meanings and contact-induced lexical change.

text: Lost in translation or lack of nuance? Perception of (near-)synonymy of common te reo Māori loanwords in New Zealand English Ongoing contact between languages and their speakers inevitably leads to a flow of words being borrowed from one language into another. Research in the field of language contact has established and documented the kinds of borrowed words that stick in their recipient language (Haspelmath 2009; Winford 2010). However, one question that has received comparatively less attention is how a newly adopted loanword relates to the structure of the existing lexicon it enters. In recent years, language contact research has thus seen a paradigm shift towards an onomasiological perspective (see Anderson et al. 2017; Crombez et al. 2022; Zenner et al. 2023). Within this approach, most studies looking at lexical variation between loanwords and their (near-)synonyms employ corpus linguistics methods (e.g. Onysko & Winter-Froemel 2011; Soares da Silva 2013). However, there is variation in how these corpus studies have investigated loanword meanings, and, to our knowledge, there has been almost no experimental research focussed specifically on the relationship between loanwords and their (near-)synonyms to date. This project presents a large-scale experimental approach from a case-study examining Māori loanwords borrowed into New Zealand English (NZE). NZE presents an unusual language contact situation because it involves a dominant language (NZE) receiving an exceptionally high amount of lexical material (words and phrases) from an Indigenous language: Māori. Further adding to the uniqueness of this contact situation is the fact that only a fraction of the population (<10%) speaks Māori fluently (Statistics New Zealand 2019). Nonetheless, Māori loanwords are ubiquitous, salient, and probably still increasing within the NZE lexicon (Macalister 2007; Trye et al. 2019). One important dimension of this set of borrowings are their semantic characteristics, which straddle three main classes of words: flora and fauna (mānuka ‘tea tree’), material culture (maunga ‘mountain’) and social culture (mana ‘power’).  Here, we report on a Qualtrics experiment devised to probe the perceived relationship between 60 Māori loanwords and their NZE equivalents, as ascertained from published sources. The synonymy judgements were elicited for pairs (e.g. whānau – family) using an analogue slider (ranging from 0 = non-synonymous to 100 = fully synonymous). Data was collected using a three-tiered questionnaire: 1) assessing synonymy of loanwords; 2) eliciting strategies for semantic assessments; and 3) collating background information about participants. Following cleaning and exclusions, the dataset showed a skew towards female participants, and for this reason, we focus our statistical analysis on the core sample containing (n = 170) young women (18-24 years). The results of the synonymy judgements analysis consist of qualitative inspections of box plots in relation to the semantic characteristics of Māori words in question, as well as sociodemographic variables of interest, specifically: years lived in Aotearoa NZ, and a composite score capturing exposure to and attitude towards Māori (TRMO). Preliminary findings suggest that many people think Māori loanwords are (highly) synonymous with NZE lexical alternatives. Our regression analyses exhibit evidence that years lived in Aotearoa NZ (p = 0.0054) and TRMO (p = 8.26e-10) can predict knowledge of Māori words. No statistically significant evidence was found for any predictors regarding the scores of the synonymy judgements; instead, we found that the random effects account for most of the variation. This is indicative of idiosyncratic loanword behaviour, in line with situations where variation is in-flux. These findings will be complemented by qualitative analyses of comments provided by participants in the open answer section (2). The talk will conclude with a summary of contributions to the general understanding of loanword meanings and contact-induced lexical change.

year: 2024