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Field-induced phase transitions in chiral smectic liquid crystals studied by the constant current method

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Chinese Physics B 2016年第5期25卷 373-379页

作者： H Dhaouadi R Zgueb O riahi F Trabelsi T Othman Departement de physiqu Faculte des Sciences de Tunis Laboratoire de physique de la matiere molle et de modelisation electromagnetique (LP3ME) Universite Tunis Elmanar Campus universitaire 2092 Tunis Tunisia

In ferroelectric liquid crystals, phase transitions can be induced by an electric field. The current constant method allows these transition to be quickly localized and thus the（E, T） phase diagram of the studied product can be *** this work, we make a slight modification to the measurement principles based on this method. This modification allows the characteristic parameters of ferroelectric liquid crystal to be quantitatively measured. The use of a current square signal highlights a phenomenon of ferroelectric hysteresis with remnant polarization at null field, which points out an effect of memory in this compound.

关键词： chiral smectic liquid crystal constant current method ferroelectric polarization dielectric permittivity

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Grandma Rules

China Weekly 2024年第8期 63-63页

作者： sam Duckett 不详

As my daughter gets ready to enjoy her first summer holiday,I can't help but reminisce about my own summer holidays from school back in *** nan and I would have cinema dates,binge-watch Disney movies,and if we were feeling particularly adventurous,a big day trip to Thorpe Park-one of England's better amusement *** I don't think I could have handled the level of excitement my daughter has experienced this summer.

关键词： daughter Grand handle

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Frozen Joy

China Weekly 2024年第2期 63-63页

作者： sam Duckett 不详

As Christmas approached,Beijing was unexpectedly blessed with heavy *** be told,I went back and forth on whether to use the word“blessed”or“cursed,”but we can talk more about my Grinch-like nature later in the *** up in the drizzling streets of southeast England,a white Christmas was something I had only ever seen in *** to think of it,during my more than 10 years in Beijing,it's been somewhat of a rareoccurrence heretoo.

关键词： southeast Christmas something

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Green Card Club

China Weekly 2024年第4期 63-63页

作者： sam Duckett 不详

Withtherecentunveiling of the new“5-star green card,”the issue of Chinese permanent residence permits has been a hot topic among expat *** a holder of the traditional green card-sans the fancy star on the front-it f... 详细信息

关键词： permanent holder Green

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Editor's Letter

The World of Chinese 2024年第1期 1-1页

作者： sam Davies 不详

China is an education powerhouse. The country’s universities produced nearly 12 million graduates last year, while 18 million teachers in public schools prepared students for exams. But changes are afoot in this giant education sector. This issue’s cover story delves into new trends and strains impacting teachers, students, and universities.

关键词： while education Letter

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Dancing with a Star

China Weekly 2024年第7期 62-62页

作者： sam Duckett 不详

It was just an ordinary day in Beijing when I got a message from my daughter's kindergarten about an upcoming school dance *** first,I thought,"How delightful,I can't wait to see her perform!"To my dismay,I discovered... 详细信息

关键词： daughter dis ordinary

A predictive equation for residual strength using a hybrid of subset selection of maximum dissimilarity method with Pareto optimal multi-gene genetic programming

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Geoscience Frontiers 2021年第5期12卷 342-354页

作者： Hossien riahi-Madvar Mahsa Gholami Bahram Gharabaghi Seyed Morteza Seyedian Department of Water Engineering Faculty of AgricultureVali-e-Asr University of RafsanjanRafsanjanIran Department of Civil Engineering Faculty of EngineeringBu-Ali Sina UniversityHamedanIran School of Engineering University of GuelphGuelphOntario N1G 2W1Canada Department of Water Engineering Faculty of AgricultureGhonbad Kavous UniversityGhonbad KavousIran

More accurate and reliable estimation of residual strength friction angle(/r)of clay is crucial in many geotechnical engineering applications,including riverbank stability analysis,design,and assessment of earthen dam slope ***,a general predictive equation for/r,with applicability in a wide range of effective parameters,remains an important research *** goal of this study is to develop a more accurate equation for/r using the Pareto Optimal Multi-gene Genetic Programming(POMGGP)approach by evaluating a comprehensive dataset of 290 experiments compiled from published literature databases worldwide.A new framework for integrated equation derivation proposed that hybridizes the Subset Selection of Maximum Dissimilarity Method(SSMD)with Multi-gene Genetic Programming(MGP)and Pareto-optimality(PO)to find an accurate equation for/r with wide range *** final predictive equation resulted from POMGGP modeling was assessed in comparison with some previously published machine learning-based equations using statistical error analysis criteria,Taylor diagram,revised discrepancy ratio(RDR),and scatter *** on the results,the POMGGP has the lowest uncertainty with U95=2.25,when compared with Artificial Neural Network(ANN)(U95=2.3),Bayesian Regularization Neural Network(BRNN)(U95=2.94),Levenberg-Marquardt Neural Network(LMNN)(U95=3.3),and Differential Evolution Neural Network(DENN)(U95=2.37).The more reliable results in estimation of/r derived by POMGGP with reliability 59.3%,and resiliency 60%in comparison with ANN(reliability=30.23%,resiliency=28.33%),BRNN(reliability=10.47%,resiliency=10.39%),LMNN(reliability=19.77%,resiliency=20.29%)and DENN(reliability=27.91%,resiliency=24.19%).Besides the simplicity and ease of application of the new POMGGP equation to a broad range of conditions,using the uncertainty,reliability,and resilience analysis confirmed that the derived equation for/r significantly outperformed other existing machine learning

关键词： Earth slopes Friction angle Maximum dissimilarity Multi-gene genetic programming Pareto-optimality Residual strength

The Influencing Factors on International Students’ Online Academic Resilience under COVID-19 in China

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The Influencing Factors on International Students’ Online A...

作者： riahi Kaoutar 浙江师范大学

学位级别：硕士

随着COVID-19的爆发,中国成为了第一个采用在线学习作为特殊时期开展教育活动的国家。没有人能否认在线学习在疫情期间的所发挥的重要作用,但目前国际学生的在线学习韧性方面仍然存在一些问题,特别是对于那些在中国境外的留学生。本研... 详细信息

随着COVID-19的爆发,中国成为了第一个采用在线学习作为特殊时期开展教育活动的国家。没有人能否认在线学习在疫情期间的所发挥的重要作用,但目前国际学生的在线学习韧性方面仍然存在一些问题,特别是对于那些在中国境外的留学生。本研究聚焦于境外国际学生在线学习面临的主要障碍,以及导致这些障碍的因素,并提出了一些相应的对策,旨在帮助未来国际学生在类似情况下能够顺利开展在线学习以及提高其学业韧性。本研究采取在线调查方法,通过运用ARS-30量表分析学生学习韧性的概念及其内在因素,采用其他自编问题量表分析外在因素,旨在进一步把握影响学生学习韧性的内部和外部因素。本研究共收集问卷为430份,随机选取250份问卷对量表进行信效度检验。正态性检验显示,所有分量表的p值均小于0.05,显示数据不是正态分布;因此采用非参数检验,结果表明,所有的分量表都接受0假设,除了坚持和反思与适应性求助拒绝0假设,这可能是由于数据的随机波动。同质性检验表明,除学校支持分量表外,所有分量表的值均大于0.05,这就是数据随机波动的原因。结果表明,该量表接受0假设,且差异无统计学意义。最终结果表明,该量表的调查数据与原研究假设一致,在统计学上差异性不显著。对两个量表进行效度检验（内部因素和外部因素）,p值均大于0.8,说明数据是有效的。在信度方面,结果表明,两个量表的p值均为0.000,说明数据具有可靠性。本论文的研究结论,是基于分析每个子量表,并根据平均值来确定国际学生的学习满意度。使用了独立样本t检验来比较性别满意度的平均值,然后提供差异的百分比。第一个量表是“毅力”,大多数国际学生在毅力上得分较高（平均3.77＞3.40）,女性得分高于男性得分（3.80＞3.74）,其中女性占52.7%,男性占47.3%。第二量表是“反思与适应性求助”,数据均值为3.84,大于3.4而小于4.20,女生（m=3.92,53.4%）在这一方面得分高于男生（m=3.75,46.6%）。最后一个分量表称为“负面影响和情绪反应”,该量表的平均值为2.45（1.80＜2.45＜2.60）,从统计学意义上看,女生得分（m=0.97,54.1%）低于男生（m=2.54,45.9%）。此外,自编量表由三个分量表构成包括:导师学术指导、学校支持、家庭支持。在“导师学术指导”量表中,均值为3.77（3.40≤3.77≤4.20）,这个数据意味着疫情期间学生接受学术指导,女生对导师学术指导满意度（m=3.79,52.6%）高于男性（m=3.75,47.4%）。在“学校支持”量表中,均值为2.4343小于分歧水平的上限（2.60）,这一因素与学生对获得大学支持的分歧有关,而女性对学校支持不满度（m=2.50,53.8%）高于男性（m=2.35,46.2%）。最后一个分量表是“家庭支持”,该分量表的均值为3.56（3.40＜3.56＜4.20）,表示学生对家庭支持方面较为满意,并对量表中的相关陈述表示认同。在该量表中,女性的认同度高于男性（3.61,53%≥3.50,47%）。研究结果表明,在新冠肺炎疫情期间,国际学生在线学习的过程中遇到了一些障碍,这些障碍在其他文献中也有所提及,主要包括焦虑和抑郁、压力、孤立、缺乏交流互动、学习动力和社会支持等,所有这些障碍都不利于国际学生线上学习的韧性建设。同时,本研究表明国际学生在毅力方面得分较好、且当需要时会寻求他人的帮助、对接受导师和家庭的帮助都持赞同态度,学生们在线学习时表现出了面对负面情绪的分歧,而且他们不同意没有得到他们的大学的任何支持。男女学生在满意度存在性别差异,在所有的分量表中,女性比男性表现得分更高。研究结果得到了先前相关研究的支持,许多研究认为,在相关分量表中,女生比男生表现出更多的认同。

关键词：学习韧性在线学习韧性留学生新冠肺炎在线学习中国

Invariant G^(2)V algorithm for computing SAGBI-Grobner bases

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Science China Mathematics 2013年第9期56卷 1781-1794页

作者： HASHEMI Amir M.-ALIZADEH Benyamin riahi Monireh Department of Mathematical Sciences Isfahan University of Technology Young Researchers Club Science and Research BranchIslamic Azad University Department of Mathematics Damghan University

Faugère and Rahmany have presented the invariant F5 algorithm to compute SAGBI-Grbner bases of ideals of invariant rings. This algorithm has an incremental structure, and it is based on the matrix version of F5 algorithm to use F5 criterion to remove a part of useless reductions. Although this algorithm is more efficient than the Buchberger-like algorithm, however it does not use all the existing criteria (for an incremental structure) to detect superfluous reductions. In this paper, we consider a new algorithm, namely, invariant G2V algorithm, to compute SAGBI-Grbner bases of ideals of invariant rings using more criteria. This algorithm has a new structure and it is based on the G2V algorithm; a variant of the F5 algorithm to compute Grbner bases. We have implemented our new algorithm in Maple , and we give experimental comparison, via some examples, of performance of this algorithm with the invariant F5 algorithm.

关键词： G^(2)V algorithm invariant F5 algorithm invariant G^(2)V algorithm SAGBI-Grobner bases