Cold storage condensation heat recovery system with a novel composite phase change material

© 2016 Elsevier Ltd. Using condensation heat from cold storage refrigeration systems to provide heat for domestic hot water preparation and industrial hot water supply promotes energy conservation. However, few studies have investigated cold storage condensation heat recovery using phase change materials (PCMs). In this study, a cold storage condensation heat recovery system that uses PCMs has been designed and analysed. According to the principle of energy cascade recycling, different operation modes could be effectively switched to recycle condensation heat. Furthermore, a novel and suitable phase change composite material is developed for cold storage condensation heat recovery, which has a relatively large latent heat, high thermal conductivity, and an appropriate phase change temperature (i.e. 80 °C). With carnauba wax (CW) as the PCM and expanded graphite (EG) as the additive, a composite was developed with an optimal mass ratio of CW:EG = 10:1. The thermal and physical properties and the interior structure of the composite were then investigated using a scanning electron microscope (SEM), thermal constants analyser (Hot Disk), differential scanning calorimeter (DSC), and Fourier transform infrared spectrometer (FT-IR). Furthermore, experiments on the melting and solidification processes and accelerated thermal cycling were also conducted. It was found that at the optimal mass ratio of 10:1, the temperatures of the CW/EG composite in the melting and solidification processes were 81.98 °C and 80.43 °C, respectively, while the corresponding latent heats were 150.9 J/g and 142.6 J/g, respectively. During both processes, CW could retain its original worm-like structure after being completely adsorbed by EG. Compared to only CW, the melting and solidification time of the CW/EG composite were reduced by 81.7% and 55.3%, respectively, while its thermal conductivity was 16.4 times higher. After 1000 runs of accelerated thermal cycling, the endothermic/exothermic phase change temperatures of CW and the CW/EG composite increased by only 0.42%/0.42% and 0.23%/0.27%, respectively, while their endothermic/exothermic latent heats decreased by 4.96%/4.78% and 2.05%/3.44%, respectively. These results indicate that both CW and the CW/EG composite have excellent thermal reliability, while the CW/EG composite exhibits a slightly better performance. Finally, the experiments show that the CW/EG composite has desirable thermal and physical properties such as high thermal conductivity and reliability; Hence, it has good potenti al as a material for facilitating condensation heat recovery from cold storage refrigeration systems

Educação moral no ensino de português como língua estrangeira na China: perspectivas e práticas no nível elementar

RESUMO: Para promover o desenvolvimento integral dos alunos, a educação moral baseada no currículo, que integra a formação de valores à construção de conhecimentos e ao desenvolvimento de competências, tem sido um tema central nas reformas pedagógicas do ensino superior na China nos últimos anos. Este artigo tem como objetivo explorar práticas pedagógicas de educação moral no ensino de Português como Língua Estrangeira (PLE) no nível elementar, utilizando três abordagens principais: o ensino de fonética, a exploração de textos didáticos e a introdução à cultura lusófona. Ao longo do ano letivo de 2023-2024, foi implementada uma intervenção pedagógica numa disciplina optativa de Português Elementar na Universidade de Jilin, e a eficácia da educação moral foi avaliada por meio de observações em sala de aula e análises quantitativas e qualitativas dos questionários. Os resultados indicam que as três estratégias utilizadas—atividades de expansão fonética, exploração de elementos morais nos textos e introdução da cultura lusófona—não apenas enriqueceram o conteúdo curricular, como também contribuíram para uma formação mais integral dos alunos, unindo o desenvolvimento de competências linguísticas à interiorização de valores éticos. O estudo também identificou desafios, como a necessidade de sistematizar os elementos da educação moral e de criar materiais didáticos mais adequados para os diferentes níveis de PLE. Espera-se que este estudo contribua para a reflexão sobre a integração da educação moral no ensino de PLE

Desenvolvimento da compreensão oral em Português Língua Segunda com recurso a materiais semi-autênticos

Oral comprehension plays a crucial role in the development of the communicative competence of a foreign language. It is also considered to be the most difficult skill to learn due to its intrinsic nature. When it comes to the teaching and learning of oral comprehension in the classroom, the didactic materials are an indispensable element in carrying out activities. In this sense, using action research methodology, a project was developed with A1.2 level students, within the scope of the pedagogical internship of the Masters in Portuguese as Second Language/Foreign Language, of the Faculty of Arts of University of Porto, with the main objective of developing the oral comprehension of learners of Portuguese as a Second Language, through the creation of semi-authentic resources. After analysing the results, we can conclude that: i.) the application of the class model centred on oral comprehension - pre-activity, activity and postactivity - contributes not only to the success of the activity of oral comprehension, but also promotes the development of other competences, especially linguistic competence in the areas of oral expression and interaction; ii.) the audio and audiovisual materials created during the pedagogical intervention constitute an asset for the enrichment of didactic materials for the learners of Portuguese as a Second Language.La comprensión oral juega un papel crucial en el desarrollo de la competencia comunicativa en una lengua extranjera. También se considera la habilidad más difícil de aprender debido a su naturaleza intrínseca. Para la enseñanza y aprendizaje de la comprensión oral en el aula, los materiales didácticos de comprensión oral son un elemento indispensable en la realización de las actividades. En este sentido, utilizando la metodología de investigación-acción, se desarrolló un proyecto con estudiantes de nivel A1.2, en el marco de la pasantía pedagógica de la Maestría en Portugués como Lengua Segunda/Lengua Extranjera, en la Facultad de Artes de la Universidad de Porto, con el objetivo principal de desarrollar la comprensión oral de los estudiantes de Portugués como Lengua Segunda, a través de la creación de recursos semiauténticos. Analizando los resultados obtenidos, podemos afirmar que, i.) La aplicación del modelo de la clase centrada en la comprensión oral - pre-actividad, actividad y post-actividad contribuye no solo al éxito de la actividad de comprensión oral, sino también promueve el desarrollo de otras habilidades, especialmente la competencia lingüística en términos de expresión e interacción orales; ii.) los materiales de audio y audiovisuales creados durante la intervención pedagógica constituyen un activo para el enriquecimiento de los materiales didácticos destinados a los estudiantes de Portugués como Lengua Segunda.A compreensão oral assume um papel crucial no desenvolvimento da competência comunicativa de uma língua estrangeira. É também considerada como a competência mais difícil de aprender devido à sua natureza intrínseca. Para o ensino-aprendizagem da compreensão oral na sala de aula, os materiais didáticos de compreensão oral constituem um elemento indispensável na realização de atividades. Nesse sentido, com recurso a metodologia de investigação-ação, foi desenvolvido um projeto junto de alunos de nível A1.2, no âmbito do estágio pedagógico do Mestrado em Português Língua Segunda/Língua Estrangeira, da Faculdade de Letras da Universidade do Porto, com o objetivo principal de desenvolver a compreensão oral dos aprendentes de Português Língua Segunda, através da criação dos recursos semi-autênticos. Analisando os resultados obtidos, podemos afirmar que, i.) a aplicação do modelo da aula centrada na compreensão oral - pré-atividade, atividade e pós-atividade - contribui não só para o sucesso da atividade de compreensão oral, como promove também o desenvolvimento de outras competências, sobretudo a competência linguística nas vertentes da expressão e interação oral; ii.) os materiais áudio e audiovisuais criados ao longo da intervenção pedagógica constituem uma mais-valia para o enriquecimento de materiais didáticos destinados aos aprendentes de Português Língua Segunda

Relaxation of the one child policy and trends in caesarean section rates and birth outcomes in China between 2012 and 2016: observational study of nearly seven million health facility births.

OBJECTIVE: To examine how the relaxation of the one child policy and policies to reduce caesarean section rates might have affected trends over time in caesarean section rates and perinatal and pregnancy related mortality in China. DESIGN: Observational study. SETTING: China's National Maternal Near Miss Surveillance System (NMNMSS). PARTICIPANTS: 6 838 582 births at 28 completed weeks or more of gestation or birth weight ≥1000 g in 438 hospitals in the NMNMSS between 2012 and 2016. MAIN OUTCOME MEASURES: Obstetric risk was defined using a modified Robson classification. The main outcome measures were changes in parity and age distributions and relative frequency of each Robson group, crude and adjusted trends over time in caesarean section rates within each risk category (using Poisson regression with a robust variance estimator), and trends in perinatal and pregnancy related mortality over time. RESULTS: Caesarean section rates declined steadily between 2012 and 2016 (crude relative risk 0.91, 95% confidence interval 0.89 to 0.93), reaching an overall hospital based rate of 41.1% in 2016. The relaxation of the one child policy was associated with an increase in the proportion of multiparous births (from 34.1% in 2012 to 46.7% in 2016), and births in women with a uterine scar nearly doubled (from 9.8% to 17.7% of all births). Taking account of these changes, the decline in caesarean sections was amplified over time (adjusted relative risk 0.82, 95% confidence interval 0.81 to 0.84). Caesarean sections declined noticeably in nulliparous women (0.75, 0.73 to 0.77) but also declined in multiparous women without a uterine scar (0.65, 0.62 to 0.77). The decrease in caesarean section rates was most pronounced in hospitals with the highest rates in 2012, consistent with the government's policy of targeting hospitals with the highest rates. Perinatal mortality declined from 10.1 to 7.2 per 1000 births over the same period (0.87, 0.83 to 0.91), and there was no change in pregnancy related mortality over time. CONCLUSIONS: China is the only country that has succeeded in reverting the rising trends in caesarean sections. China's success is remarkable given that the changes in obstetric risk associated with the relaxation of the one child policy would have led to an increase in the need for caesarean sections. China's experience suggests that change is possible when strategies are comprehensive and deal with the system level factors that underpin overuse as well as the various incentives at work during a clinical encounter

Structured Memetic Automation for Online Human-like Social Behavior Learning

Meme automaton is an adaptive entity that autonomously acquires an increasing level of capability and intelligence through embedded memes evolving independently or via social interactions. This paper begins a study on memetic multiagent system (MeMAS) toward human-like social agents with memetic automaton. We introduce a potentially rich meme-inspired design and operational model, with Darwin's theory of natural selection and Dawkins' notion of a meme as the principal driving forces behind interactions among agents, whereby memes form the fundamental building blocks of the agents' mind universe. To improve the efficiency and scalability of MeMAS, we propose memetic agents with structured memes in this paper. Particularly, we focus on meme selection design where the commonly used elitist strategy is further improved by assimilating the notion of like-attracts-like in the human learning. We conduct experimental study on multiple problem domains and show the performance of the proposed MeMAS on human-like social behavior

Improved isolation of cadmium from paddy soil by novel technology based on pore water drainage with graphite-contained electro-kinetic geosynthetics

Novel soil remediation equipment based on electro-kinetic geosynthetics (EKG) was developed for in situ isolation of metals from paddy soil. Two mutually independent field plot experiments A and B (with and without electric current applied) were conducted. After saturation using ferric chloride (FeCl3) and calcium chloride (CaCl2), soil water drainage capacity, soil cadmium (Cd) removal performance, energy consumption as well as soil residual of iron (Fe) and chloride (Cl) were assessed. Cadmium dissolved in the soil matrix and resulted in a 100% increase of diethylenetriamine-pentaacetic acid (DTPA) extracted phyto-available Cd. The total soil Cd content reductions were 15.20% and 26.58% for groups A and B, respectively, and electric field applications resulted in a 74.87% increase of soil total Cd removal. The electric energy consumption was only 2.17 kWh/m3 for group B. Drainage by gravity contributed to > 90% of the overall soil dewatering capacity. Compared to conventional electro-kinetic technology, excellent and fast soil water drainage resulted in negligible hydrogen ion (H+) and hydroxide ion (OH−) accumulation at nearby electrode zones, which addressed the challenge of anode corrosion and cathode precipitation of soil metals. External addition of FeCl3 and CaCl2 caused soil Fe and Cl residuals and led to 4.33–7.59% and 139–172% acceptable augments in soil total Fe and Cl content, correspondingly, if compared to original untreated soils. Therefore, the novel soil remediation equipment developed based on EKG can be regarded as a promising new in situ technology for thoroughly isolating metals from large-scale paddy soil fields

Named Entity Recognition Based on Multi-scale Attention

The accuracy of named entity recognition (NER) task will promote the research of multiple downstream tasks in natural language field. Due to a large number of nested semantics in text, named entities are recognized difficultly. Recognizing nested semantics becomes a difficulty in natural language processing. Previous studies have single scale of extracting feature and under-utilization of the boundary information. They ignore many details under different scales and then lead to the situation of entity recognition error or omission. Aiming at the above problems, a multi-scale attention method for named entity recognition (MSA-NER) is proposed. Firstly, the BERT model is used to obtain representation vector containing context information, and then the BiLSTM network is used to strengthen the context representation of text. Secondly, the representation vectors are enumerated and concatenated to form span information matrix. The direction information is fused to obtain richer interactive information. Thirdly, multi-head attention is used to construct multiple subspaces. Two-dimensional convolution is used to optionally aggregate text information at different scales in each subspace, so as to implement multi-scale feature fusion in each attention layer. Finally, the fused matrix is used for span classification to identify named entities. Experimental results show that the [F1] score of the proposed method reaches 81.7% and 86.8% on GENIA and ACE2005 English datasets, respectively. The proposed method demonstrates better recognition performance compared with existing mainstream models

The Strain Seismograms of P- and S-Waves of a Local Event Recorded by Four-Gauge Borehole Strainmeter

At a sampling rate of 100 samples per second, the YRY-4 four-gauge borehole strainmeters (FGBS) are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a high sampling rate, data from the YRY-4 strainmeters demonstrate fairly satisfactory self-consistency. The strain tensor seismograms demonstrate the senses of motion of P waves, that is, the type of seismic wave travels in the direction of the maximum normal strain change. The observed strain patterns of S waves significantly differ from those of P waves and should contain information about the source mechanism. Spectrum analysis shows that the strain seismograms are consistent with conventional broadband seismograms from the same site