A New Evaluation Circuit with a Low-Voltage Inverter Intended for Capacitors Used in a High-power Three-phase Inverter

DC-link capacitors in power electronic converters are a major constraint on improvement of power density as well as reliability. Evaluation of the dc-link capacitors in terms of power loss, ageing, and failure rate will play an important role in design stages of the next-generation power converters. This paper proposes a new evaluation circuit for dc-link capacitors used in a high-power three-phase inverter, which is intended for testing power loss, failure rate, ageing, and so on. The evaluation circuit produces a practical ripple current waveform and a dc bias voltage into a capacitor under test, in which the ripple current is equivalent to that generated by the three-phase inverter on the dc link. The evaluation circuit employs a full-scale current-rating and downscaled voltage-rating inverter for producing the ripple current, so that the power rating of the evaluation circuit is much smaller than that of a full-scale current rating and full-scale voltage rating inverter.2016 IEEE Applied Power Electronics Conference and Exposition (APEC 2016), March 20-24, 2016, Long Beach, California, US

Design and Analysis of a New Evaluation Circuit for Capacitors Used in a High-Power Three-Phase Inverter

DC-link capacitors in power electronic converters are a major constraint on improvement of power density as well as reliability. Evaluation of the dc-link capacitors in terms of power loss, ageing, and failure rate will play an important role in design stages of the next-generation power converters. This paper proposes a new evaluation circuit for dc-link capacitors used in a high-power three-phase inverter, which is intended for testing power loss, failure rate, ageing, and so on. The evaluation circuit produces a practical ripple current waveform and a dc bias voltage into a capacitor under test, in which the ripple current is equivalent to that generated by the three-phase inverter on the dc link. The evaluation circuit employs a full-scale current-rating and downscaled voltage-rating inverter for producing the ripple current, so that the power rating of the evaluation circuit is much smaller than that of a full-scale current-rating and full-scale voltage-rating inverter. Theoretical analysis and simulated results verify the effectiveness of new evaluation circui

A New Evaluation Circuit with a Low-Voltage Inverter Intended for Capacitors Used in a High-power Three-phase Inverter

016 IEEE Applied Power Electronics Conference and Exposition (APEC 2016), March 20-24, 2016, Long Beach, California, USADC-link capacitors in power electronic converters are a major constraint on improvement of power density as well as reliability. Evaluation of the dc-link capacitors in terms of power loss, ageing, and failure rate will play an important role in design stages of the next-generation power converters. This paper proposes a new evaluation circuit for dc-link capacitors used in a high-power three-phase inverter, which is intended for testing power loss, failure rate, ageing, and so on. The evaluation circuit produces a practical ripple current waveform and a dc bias voltage into a capacitor under test, in which the ripple current is equivalent to that generated by the three-phase inverter on the dc link. The evaluation circuit employs a full-scale current-rating and downscaled voltage-rating inverter for producing the ripple current, so that the power rating of the evaluation circuit is much smaller than that of a full-scale current rating and full-scale voltage rating inverter

Vegetation development on the glacier moraines in Oobloyah Valley, Ellesmere Island high arctic Canada

The process of the vegetation development on glacier moraines was surveyed in the lower stream area of Oobloyah Valley (80°50\u27N, 82°45\u27W), Ellesmere Island, high arctic Canada. Four glacier moraines, and an outwash plane with different establishment periods in the proglacial field of Arklio Glacier, were surveyed .The oldest moraine was estimated to have been established during the Full Glacial, ca. 25000-35000 years ago, and the youngest one during the Little Ice Age, ca. 250 years ago. The vegetation properties such as number of species per study plot, cover of vegetation, lichens and bryophytes showed constant increase the moraine age, suggesting directional vegetation development. Changes in the species composition were such that new species successively appeared during the establishment of the moraines without obvious replacement of the species. It was concluded that the manner of the vegetation development was directional-nonreplacement succession even under extreme high arctic environment, differing from the generally accepted view that under an extreme high arctic environment nondirectional-nonreplacement succession prevails. Vegetation physiognomy approached Cassiope tetragona-dominated dwarf shrub heath, which generally prevails in more southern regions than Ellesmere Island. The period required for the vegetation development in the study area was assumed to be quite long, probably at least ca. 20000 years

An Evaluation Circuit for DC-Link Capacitors used in a Single-Phase PWM Inverter

High-power conversion systems are based not only on three-phase inverters but also on single-phase inverters because modular multilevel cascade converters (MMCC) consist of half- or full-bridge single-phase converters. Their DC-link capacitors are a major constraint on the improvement of power density as well as of reliability. Evaluation of dc-link capacitors in terms of power loss, ageing, and failure rate will play an important role in the next-generation power converters. This paper presents an evaluation circuit for dc-link capacitors used in a high-power single-phase PWM inverter. The evaluation circuit produces a practical ripple current waveform and a dc bias voltage into a capacitor under test with a downscaled voltage-rating inverter, which is equivalent to those of the full-scale inverter. Theoretical analysis and experimental results verify the effectiveness of the evaluation circuitPCIM Europe 2017, 16 – 18 May, 2017, Nuremberg, German

Causes and consequences of stress generation : Longitudinal associations of negative events, aggressive behaviors, rumination, and depressive symptoms

The present study examined the causes and consequences of stress generation in university students in Japan. A two-wave longitudinal study with an 8- or 9-week interval was conducted in the fall of 2020. Undergraduate and graduate students at four universities in Japan (N = 201) completed self-report measures assessing experiences of negative interpersonal dependent events, negative non-interpersonal events, and negative independent events at two times. At the same time, they also responded to measures of aggressive behaviors, trait rumination, and depressive symptoms. Path analyses revealed that baseline aggressive behaviors were positively associated with an increase in subsequent negative interpersonal dependent events, even after controlling for the influences of negative interpersonal dependent events, rumination, and depressive symptoms at baseline. However, aggressive behaviors were not significantly associated with subsequent negative non-interpersonal dependent events or negative independent events. These findings suggest that aggressive behaviors may have been a factor leading to interpersonal stress generation. Furthermore, all categories of negative event experiences predicted an increase in subsequent depressive symptoms, but not subsequent rumination, and rumination was not significantly associated with subsequent depressive symptoms. This research extends previous studies on the causes and consequences of stress generation conducted in the US by using specific measures of aggressive behaviors and including a non-restricted sample of university students in Japan

Potent prion-like behaviors of pathogenic α-synuclein and evaluation of inactivation methods

The concept that abnormal protein aggregates show prion-like propagation between cells has been considered to explain the onset and progression of many neurodegenerative diseases. Indeed, both synthetic amyloid-like fibrils and pathogenic proteins extracted from patients’ brains induce self-templated amplification and cell-to-cell transmission in vitro and in vivo. However, it is unclear whether exposure to exogenous prion-like proteins can potentially cause these diseases in humans. Here, we investigated in detail the prion-like seeding activities of several kinds of pathogenic α-synuclein (α-syn), including synthetic fibrils and detergent-insoluble fractions extracted from brains of patients with α-synucleinopathies. Exposure to synthetic α-syn fibrils at concentrations above 100 pg/mL caused seeded aggregation of α-syn in SH-SY5Y cells, and seeded aggregation was also observed in C57BL/6 J mice after intracerebral inoculation of at least 0.1 μg/animal. α-Syn aggregates extracted from brains of multiple system atrophy (MSA) patients showed higher seeding activity than those extracted from patients with dementia with Lewy bodies (DLB), and their potency was similar to that of synthetic α-syn fibrils. We also examined the effects of various methods that have been reported to inactivate abnormal prion proteins (PrPSc), including autoclaving at various temperatures, exposure to sodium dodecyl sulfate (SDS), and combined treatments. The combination of autoclaving and 1% SDS substantially reduced the seeding activities of synthetic α-syn fibrils and α-syn aggregates extracted from MSA brains. However, single treatment with 1% SDS or generally used sterilization conditions proved insufficient to prevent accumulation of pathological α-syn. In conclusion, α-syn aggregates derived from MSA patients showed a potent prion-like seeding activity, which could be efficiently reduced by combined use of SDS and autoclaving

Five Amino Acid Residues Responsible for the High Stability of Hydrogenobacter thermophilus Cytochrome c552

Five amino acid residues responsible for extreme stability have been identified in cytochrome c552 (HT c552) from a thermophilic bacterium, Hydrogenobacter thermophilus. The five residues, which are spatially distributed in three regions of HT c552, were replaced with the corresponding residues in the homologous but less stable cytochrome c551 (PA c551) from Pseudomonas aeruginosa. The quintuple HT c552 variant (A7F/M13V/Y34F/Y43E/I78V) showed the same stability against guanidine hydrochloride denaturation as that of PA c551, suggesting that the five residues in HT c552 necessarily and sufficiently contribute to the overall stability. In the three HT c552 variants carrying mutations in each of the three regions, the Y34F/Y43E mutations resulted in the greatest destabilization, by –13.3 kJ mol–1, followed by A7F/M13V (–3.3 kJ mol–1) and then I78V (–1.5 kJ mol–1). The order of destabilization in HT c552 was the same as that of stabilization in PA c551 with reverse mutations such as F34Y/E43Y, F7A/V13M, and V78I (13.4, 10.3, and 0.3 kJ mol–1, respectively). The results of guanidine hydrochloride denaturation were consistent with those of thermal denaturation for the same variants. The present study established a method for reciprocal mutation analysis. The effects of side-chain contacts were experimentally evaluated by swapping the residues between the two homologous proteins that differ in stability. A comparative study of the two proteins was a useful tool for assessing the amino acid contribution to the overall stability.This work was supported in part by grants from Hiroshima University, the Noda Institute for Scientific Research, and the Japanese Ministry of Education, Science and Culture (grants-in-aid for Scientific Research on Priority Areas)