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A graphene composite aerogel with a high thermal conductivity,compressibility and flexibility meets the requirements of phase-change materials for rigid-flexible material innovation
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作者 CUI Jia-ming CHEN Yi-xing +1 位作者 XU Wen-tao WANG Sheng 《新型炭材料(中英文)》 北大核心 2025年第5期1136-1153,共18页
Oriented graphene aerogels have limited applica-tions because the flexibility of their graphene sheets and mi-crostructure give them a low skeleton strength,insufficient compression resilience,and poor flexibility.We ... Oriented graphene aerogels have limited applica-tions because the flexibility of their graphene sheets and mi-crostructure give them a low skeleton strength,insufficient compression resilience,and poor flexibility.We report the preparation of novel aerogel materials with a much better per-formance.Using the driving force of graphene oxide(GO)self-assembly andπ-πinteractions,carbon nanotubes(CNTs)were attached to the GO sheets,and an oriented composite carbon skeleton was constructed using“hydro-plastic foam-ing”.The introduction of CNTs significantly increased the strength of the skeleton and gave the aerogel an excellent re-versible compressibility.The innovative use of cold pressing greatly improved the thermal conductivity and flexibility of the aerogel,providing new ideas for the development of high-performance aerogels.Tests show that the obtained graphene composite aerogel has a reversible compressive strain of over 90%and can withstand 500 compression cycles along the direc-tion of pore accumulation.It can endure more than 10000 bending cycles perpendicular to the direction of composite carbon layer stacking,and its in-plane thermal conductivity reaches 64.5 W·m^(-1)·K^(-1).When filled with phase change materials,the high porosity of the carbon skeleton enables the material to have a high phase change filling rate,and its phase change enthalpy is greater than 150 J/g.Thanks to the exceptional flexibility of the carbon skeleton,the macrostructure of phase change materials can be bent as needed to adapt to thermal management scenarios and conform to device shapes.This significantly enhances practical application compatibility,providing flexible support for temperature control and thermal management across diverse device forms. 展开更多
关键词 Oriented graphene aerogel GO CNT Hydro-plastic foaming Phase change material
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Predicting Hepatocellular Carcinoma Using Brightness Change Curves Derived From Contrast-enhanced Ultrasound Images
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作者 CHEN Ying-Ying JIANG Shang-Lin +3 位作者 HUANG Liang-Hui ZENG Ya-Guang WANG Xue-Hua ZHENG Wei 《生物化学与生物物理进展》 北大核心 2025年第8期2163-2172,共10页
Objective Primary liver cancer,predominantly hepatocellular carcinoma(HCC),is a significant global health issue,ranking as the sixth most diagnosed cancer and the third leading cause of cancer-related mortality.Accura... Objective Primary liver cancer,predominantly hepatocellular carcinoma(HCC),is a significant global health issue,ranking as the sixth most diagnosed cancer and the third leading cause of cancer-related mortality.Accurate and early diagnosis of HCC is crucial for effective treatment,as HCC and non-HCC malignancies like intrahepatic cholangiocarcinoma(ICC)exhibit different prognoses and treatment responses.Traditional diagnostic methods,including liver biopsy and contrast-enhanced ultrasound(CEUS),face limitations in applicability and objectivity.The primary objective of this study was to develop an advanced,lightweighted classification network capable of distinguishing HCC from other non-HCC malignancies by leveraging the automatic analysis of brightness changes in CEUS images.The ultimate goal was to create a user-friendly and cost-efficient computer-aided diagnostic tool that could assist radiologists in making more accurate and efficient clinical decisions.Methods This retrospective study encompassed a total of 161 patients,comprising 131 diagnosed with HCC and 30 with non-HCC malignancies.To achieve accurate tumor detection,the YOLOX network was employed to identify the region of interest(ROI)on both B-mode ultrasound and CEUS images.A custom-developed algorithm was then utilized to extract brightness change curves from the tumor and adjacent liver parenchyma regions within the CEUS images.These curves provided critical data for the subsequent analysis and classification process.To analyze the extracted brightness change curves and classify the malignancies,we developed and compared several models.These included one-dimensional convolutional neural networks(1D-ResNet,1D-ConvNeXt,and 1D-CNN),as well as traditional machine-learning methods such as support vector machine(SVM),ensemble learning(EL),k-nearest neighbor(KNN),and decision tree(DT).The diagnostic performance of each method in distinguishing HCC from non-HCC malignancies was rigorously evaluated using four key metrics:area under the receiver operating characteristic(AUC),accuracy(ACC),sensitivity(SE),and specificity(SP).Results The evaluation of the machine-learning methods revealed AUC values of 0.70 for SVM,0.56 for ensemble learning,0.63 for KNN,and 0.72 for the decision tree.These results indicated moderate to fair performance in classifying the malignancies based on the brightness change curves.In contrast,the deep learning models demonstrated significantly higher AUCs,with 1D-ResNet achieving an AUC of 0.72,1D-ConvNeXt reaching 0.82,and 1D-CNN obtaining the highest AUC of 0.84.Moreover,under the five-fold cross-validation scheme,the 1D-CNN model outperformed other models in both accuracy and specificity.Specifically,it achieved accuracy improvements of 3.8%to 10.0%and specificity enhancements of 6.6%to 43.3%over competing approaches.The superior performance of the 1D-CNN model highlighted its potential as a powerful tool for accurate classification.Conclusion The 1D-CNN model proved to be the most effective in differentiating HCC from non-HCC malignancies,surpassing both traditional machine-learning methods and other deep learning models.This study successfully developed a user-friendly and cost-efficient computer-aided diagnostic solution that would significantly enhances radiologists’diagnostic capabilities.By improving the accuracy and efficiency of clinical decision-making,this tool has the potential to positively impact patient care and outcomes.Future work may focus on further refining the model and exploring its integration with multimodal ultrasound data to maximize its accuracy and applicability. 展开更多
关键词 computer-aided diagnostic deep learning hepatocellular carcinoma contrast-enhanced ultrasound brightness change curve
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Impacts of climate change on cotton production and advancements in genomic approaches for stress resilience enhancement
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作者 KHAN Muhammad Aamir ANWAR Saeed +5 位作者 ABBAS Mubashir ANEEQ Muhammad DE JONG Fokke AYAZ Muhammad WEI Yunxiao ZHANG Rui 《Journal of Cotton Research》 2025年第2期270-289,共20页
Cotton is an essential agricultural commodity,but its global yield is greatly affected by climate change,which poses a serious threat to the agriculture sector.This review aims to provide an overview of the impact of ... Cotton is an essential agricultural commodity,but its global yield is greatly affected by climate change,which poses a serious threat to the agriculture sector.This review aims to provide an overview of the impact of climate change on cotton production and the use of genomic approaches to increase stress tolerance in cotton.This paper discusses the effects of rising temperatures,changing precipitation patterns,and extreme weather events on cotton yield.It then explores various genomic strategies,such as genomic selection and marker-assisted selection,which can be used to develop stress-tolerant cotton varieties.The review emphasizes the need for interdisciplinary research efforts and policy interventions to mitigate the adverse effects of climate change on cotton production.Furthermore,this paper presents advanced prospects,including genomic selection,gene editing,multi-omics integration,highthroughput phenotyping,genomic data sharing,climate-informed breeding,and phenomics-assisted genomic selection,for enhancing stress resilience in cotton.Those innovative approaches can assist cotton researchers and breeders in developing highly resilient cotton varieties capable of withstanding the challenges posed by climate change,ensuring the sustainable and prosperous future of cotton production. 展开更多
关键词 COTTON Climate change Stress tolerance Genomic selection Gene editing QTLS Fiber
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Numerical simulation of dynamic Coulomb stress changes induced by M6.5 earthquake in Wuding, Yunnan and its relationship with aftershocks 被引量:6
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作者 虎雄林 吴小平 +3 位作者 杨润海 付虹 胡家富 黄雍 《地震学报》 CSCD 北大核心 2008年第1期26-35,共10页
Based on the discrete wavenumber method, we calculate the fields of dynamic Coulomb rupture stress changes and static stress changes caused by M6.5 earthquake in Wuding, and study their relationship with the subsequen... Based on the discrete wavenumber method, we calculate the fields of dynamic Coulomb rupture stress changes and static stress changes caused by M6.5 earthquake in Wuding, and study their relationship with the subsequent after- shocks. The results show that the spatial distribution patterns of the positive region of dynamic stress peak value and static stress peak value are similarly asymmetric, which are basically identical with distribution features of aftershock. The dynamic stress peak value and the static stress in the positive region are more than 0.1 MPa and 0.01 MPa of the triggering threshold, respectively, which indicates that the dynamic and static stresses are helpful for the occurrence of aftershock. This suggests that both influences of dynamic and static stresses should be con- sidered other than only either of them when studying aftershock triggering in near field. 展开更多
关键词 武定地震 动态库仑破裂应力变化 余震 动态应力触发
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基于Change-Tree的本体变更日志存储研究
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作者 邓志文 夏士雄 +1 位作者 张磊 袁冠 《计算机应用研究》 CSCD 北大核心 2009年第7期2636-2639,共4页
本体变更的目的是为了适应环境的变化,而变更的前提是要保证本体和使用它的应用或数据间的兼容性,本体概念或属性的重命名、合并、分解都可能造成本体与应用间的不兼容。提出了一种基于Change-Tree的本体变更日志存储方法。该方法采用... 本体变更的目的是为了适应环境的变化,而变更的前提是要保证本体和使用它的应用或数据间的兼容性,本体概念或属性的重命名、合并、分解都可能造成本体与应用间的不兼容。提出了一种基于Change-Tree的本体变更日志存储方法。该方法采用有向树来组织本体的变更过程,用变更树节点来存储本体变更的信息,用节点间与或关系来关联本体的变更类型;同时该方法能采用树搜索来遍历本体变更的每一个历史阶段,从而为重现本体变化的历史提供了一种灵活高效的途径。 展开更多
关键词 本体 本体变更 变更树 与或节点
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教育的费斯托 智慧的费斯托 Fit for change
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作者 汤晓华 《职业技术教育》 北大核心 2014年第30期30-31,共2页
费斯托(FESTO),慕名已久,今天终于见到了。2013年11月12日,考察FESTO公司,我们的第一站是FESTO学院。FESTO公司本身生产教学仪器和气动设备等自动化装备,这个学院的目标就是在科技发展中,使得教育不断满足企业的需要,适应未来技术领... 费斯托(FESTO),慕名已久,今天终于见到了。2013年11月12日,考察FESTO公司,我们的第一站是FESTO学院。FESTO公司本身生产教学仪器和气动设备等自动化装备,这个学院的目标就是在科技发展中,使得教育不断满足企业的需要,适应未来技术领域的发展,培训员工改善生产效率。它是世界技能大赛的设备支撑企业,在员工培训学习上有非常丰富的学习系统和网络远程授课系统。 展开更多
关键词 斯托 自动化装备 FIT for change 教学仪器 网络远程 学习系统 生产效率 科技发展 学习理论 未来技术
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英汉互译中多义词语义选择的制约因素——以“change”的汉译为例 被引量:4
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作者 谷吉梅 《华东理工大学学报(社会科学版)》 CSSCI 北大核心 2018年第6期88-94,116,共8页
词义选择是影响翻译质量的重要因素之一。英汉互译过程中往往需要进行多义词之间的语义选择,然而语义选择受多种因素制约,本文以"change"的汉译为例,运用语义、语境、认知等理论对英汉互译过程中多义词语义选择的制约因素进... 词义选择是影响翻译质量的重要因素之一。英汉互译过程中往往需要进行多义词之间的语义选择,然而语义选择受多种因素制约,本文以"change"的汉译为例,运用语义、语境、认知等理论对英汉互译过程中多义词语义选择的制约因素进行理论探讨。研究认为制约多义词词义选择的关键因素除了词的指称意义或概念意义之外,更重要的是词在语篇中所处的语境、语体及译者的语言水平及认知能力等因素。 展开更多
关键词 英汉互译 多义词 语义选择 制约因素 change
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Seismic ray-tracing calculation based on parabolic travel-time interpolation 被引量:2
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作者 周竹生 张赛民 陈灵君 《Journal of Central South University of Technology》 2004年第2期199-205,共7页
A new seismic ray-tracing method is put forward based on parabolic travel-time interpolation(PTI) method, which is more accurate than the linear travel-time interpolation (LTI) method. Both PTI method and LTI method a... A new seismic ray-tracing method is put forward based on parabolic travel-time interpolation(PTI) method, which is more accurate than the linear travel-time interpolation (LTI) method. Both PTI method and LTI method are used to compute seismic travel-time and ray-path in a 2-D grid cell model. Firstly, some basic concepts are introduced. The calculations of travel-time and ray-path are carried out only at cell boundaries. So, the ray-path is always straight in the same cells with uniform velocity. Two steps are applied in PTI and LTI method, step 1 computes travel-time and step 2 traces ray-path. Then, the derivation of LTI formulas is described. Because of the presence of refraction wave in shot cell, the formula aiming at shot cell is also derived. Finally, PTI method is presented. The calculation of PTI method is more complex than that of LTI method, but the error is limited. The results of numerical model show that PTI method can trace ray-path more accurately and efficiently than LTI method does. 展开更多
关键词 RAY-TRACING parabolic travel-time interpolation method linear travel-time interpolation method (travel-time ) ray-path grid cell
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Cool storage time of phase change wallboard room in summer 被引量:1
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作者 冯国会 陈其针 +2 位作者 黄凯良 牛润萍 王琳 《Journal of Central South University》 SCIE EI CAS 2009年第S1期75-79,共5页
More and more attention was paid to phase change energy storage in air conditioning domain and construction energy conservation,and became the focus of the international research. Through the test and analysis of the ... More and more attention was paid to phase change energy storage in air conditioning domain and construction energy conservation,and became the focus of the international research. Through the test and analysis of the parameters of the indoor thermal property in phase change wallboard room and ordinary room,the effects of using phase change wallboards on indoor temperature in summer and air conditioning are obtained. The combination of construct enclosure and phase change materials can stabilize indoor temperature,improve indoor thermal comfort,reduce the frequency of the operation of air conditioning facility,cut the initial investment and operation expense,and meanwhile play an practical role in "the power balancing between the peak period and the valley period" policy. Through the experiment and the test of the effects exerted by phase change wallboard room and ordinary room on the indoor thermal environment,it is obtained that the phase change wallboard can reduce the fluctuation range of indoor temperature and the heat flow from the outside into indoor environment in summer. According to the study,it is found that the effect of cool-storing for 5 h is obvious. Through the analysis of the phase change wallboard without air conditioning in daytime,it is obtained that the frequency of the operation of air conditioning in phase change wallboard room is smaller than that in the ordinary room,which can prolong the lifetime of the facility and reduce operation expense. 展开更多
关键词 PHASE change energy STORAGE PHASE change WALLBOARD room THERMAL STORAGE THERMAL exchange cool-storage air-conditioning
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Closed circle DNA algorithm of change positive-weighted Hamilton circuit problem 被引量:5
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作者 Zhou Kang Tong Xiaojun Xu Jin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第3期636-642,共7页
Chain length of closed circle DNA is equal. The same closed circle DNA's position corresponds to different recognition sequence, and the same recognition sequence corresponds to different foreign DNA segment, so clos... Chain length of closed circle DNA is equal. The same closed circle DNA's position corresponds to different recognition sequence, and the same recognition sequence corresponds to different foreign DNA segment, so closed circle DNA computing model is generalized. For change positive-weighted Hamilton circuit problem, closed circle DNA algorithm is put forward. First, three groups of DNA encoding are encoded for all arcs, and deck groups are designed for all vertices. All possible solutions are composed. Then, the feasible solutions are filtered out by using group detect experiment, and the optimization solutions are obtained by using group insert experiment and electrophoresis experiment. Finally, all optimization solutions are found by using detect experiment. Complexity of algorithm is concluded and validity of DNA algorithm is explained by an example. Three dominances of the closed circle DNA algorithm are analyzed, and characteristics and dominances of group delete experiment are discussed. 展开更多
关键词 closed circle DNA computing model change positive-weighted Hamilton circuit problem group insert experiment group delete experiment.
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A Model-Free Method for Structual Change Detection Multivariate Nonlinear Time Series 被引量:2
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作者 孙青华 张世英 梁雄健 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2003年第2期36-46,共11页
In this paper, we apply the recursive genetic programming (RGP) approach to the cognition of a system, and then proceed to the detecting procedure for structural changes in the system whose components are of long memo... In this paper, we apply the recursive genetic programming (RGP) approach to the cognition of a system, and then proceed to the detecting procedure for structural changes in the system whose components are of long memory. This approach is adaptive and model-free, which can simulate the individual activities of the system's participants, therefore, it has strong ability to recognize the operating mechanism of the system. Based on the previous cognition about the system, a testing statistic is developed for the detection of structural changes in the system. Furthermore, an example is presented to illustrate the validity and practical value of the proposed. 展开更多
关键词 Structural changes Recursive genetic programming Model-free method.
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Phase change microcapsules in thermal Energy applications:A critical review 被引量:1
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作者 XIAO Anna YUAN Qingchun 《储能科学与技术》 CAS CSCD 2017年第4期607-622,共16页
Phase change microcapsules can carry large amounts of heat and be dispersed into other mediums either as a solid composite or as slurry fluids without changes to their appearance or fluidity. These two standout featur... Phase change microcapsules can carry large amounts of heat and be dispersed into other mediums either as a solid composite or as slurry fluids without changes to their appearance or fluidity. These two standout features make phase change microcapsules ideal for use in thermal energy applications to enhance the efficiency of energy utilisation. This review paper includes methods used for the encapsulation of phase change materials, especially the method suitable for large scale productions, the trends of phase change microcapsule development and their use in thermal energy applications in static and dynamic conditions. The effect of phase change microcapsules on convective heat transfer through addition to thermal fluids as slurries is critically reviewed. The review highlighted that so far the phase change microcapsules used mainly have polymeric shells, which has very low thermal conductivities. Their enhancement in convective heat transfer was demonstrated in locations where the phase change material experiences phase change. The phase change results in the slurries having higher apparent local specific heat capacities and thus higher local heat transfer coefficients. Out of the phase change region, no enhancement is observed from the solid microcapsule particles due to the low specific heat capacity and thermal conductivity of the phase change microcapsules compared to that of water, which is normally used as slurry media in the test. To further the research in this area, phase change microcapsules with higher specific heat capacity, higher thermal conductivity and better shape stability need to be applied. 展开更多
关键词 phase change microcapsule complex microencapsulation SLURRY phase change patterns convective heat transfer enhancement
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Potential role of ecto-5'-nucleotidase in morphine-induced uridine release and neurobehavioral changes 被引量:1
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作者 CHE Xiao-hang LIU Ping +8 位作者 WU Chun-fu SONG Wu AN Ni-na YU Li-sha BAI Yi-jun XING Zheng CAI Jia-ling WANG Xiao-min YANG Jing-yu 《中国药理学与毒理学杂志》 CAS CSCD 北大核心 2018年第9期722-722,共1页
OBJECTIVE There is growing evidence that uridine may act as an endogenous neuromodulator with a potential signaling role in the central nervous system in addition to its function in pyrimidine metabolism.We previously... OBJECTIVE There is growing evidence that uridine may act as an endogenous neuromodulator with a potential signaling role in the central nervous system in addition to its function in pyrimidine metabolism.We previously found that acute morphine treatment significantly increased uridine release in the dorsal striatum of mice,while the mechanism involved in morphine-induced uridine release and the role of uridine in morphine-induced neurobehavioral changes have not been understood.METHODS Uridine release in the dorsal striatum of mice was assessed by in vivo microdialysis coupled with high performance liquid chromatography(HPLC) after morphine treatment.Western blotting and immunofluorescence were used to evaluate the expression of uridine-related proteins.Morphine-induced neurobehavioral changes were assessed by locomotor activity,behavioral sensitization and conditioned place preference(CPP)test.The expression of NT5E,an extracellular enzyme involved in formation of nucleosides,including uridine,was specifically knocked down in the dorsal striatum of mice using adeno-associated virus(AAV)-mediated short hairpin RNA(shRNA).RESULTS Both acute and chronic morphine administration significantly increased uridine release in the dorsal striatum,and this was associated with upregulation of NT5E but not other uridine-related proteins.Inhibition of NT5E with APCP or shRNA markedly inhibited morphine-induced uridine release in the dorsal striatum and related neurobehavioral changes,including hyperlocomotor activity,behavioral sensitization and CPP.CONCLUSION The present study increases our understanding of the contribution of NT5E in regulating morphine-induced neurobehavioral changes,at least as related to uridine,and suggests that NT5E may be a novel therapeutic target to manage morphine abuse. 展开更多
关键词 ecto-5'-nucleotidases URIDINE MORPHINE NEUROBEHAVIORAL changeS
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Antarcticite, a Phase Change Material for ThermalEnergy Storage: Experiments and Simulation 被引量:1
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作者 GU Xiaobin NIU Jingjing QIN Shan 《矿物学报》 CAS CSCD 北大核心 2013年第S1期28-28,共1页
Antarcticite, a mineral with composition CaCl2·6H2O and structure P321, is an ideal phase change material (PCM) due to the high energy storage density and good thermal conductivity. However, the existence of supe... Antarcticite, a mineral with composition CaCl2·6H2O and structure P321, is an ideal phase change material (PCM) due to the high energy storage density and good thermal conductivity. However, the existence of supercooling and incongruent melting would weaken its thermal properties and then hinder its application. In this paper, based on the cooling curve method and DSC measurement, we experimentally selected the minor SrCl2·6H2O as the nucleator and carboxyl methyl cellulose as the thickening agent, which could significantly reduce supercooling and partly restrain the incongruent melting. Moreover, we incorporated Antarcticite as PCM into building envelopes in four different cases, the simulation of the heat transfer processes showed that the temperature fluctuation could be reduced to about 2℃ in the best case. 展开更多
关键词 Antarcticite PHASE change MATERIAL SUPERCOOLING simulation
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Preparation and hygrothermal performance of composite phase change material wallboard with humidity control based on expanded perlite/diatomite/paraffin 被引量:14
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作者 YANG Hua LIU Yun +2 位作者 KONG Xiang-fei CHEN Wan-he YAO Cheng-qiang 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第10期2387-2398,共12页
Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CP... Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CPCMPs)were prepared by vacuum impregnation method with expanded perlite(EP)as supporting material and paraffin as phase change material.Thus,a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard(CPCHCW)was prepared by spraying the diatom mud on the surface of PCM plate.The composition,thermophysical properties and microstructure were characterized using X-ray diffraction instrument(XRD),differential scanning calorimeter(DSC)and scanning electron microscope(SEM).Additionally,the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test.The results can be summarized as follows:(1)CPCMPs have suitable phase change parameters with melting/freezing point of 18.23°C/29.42°C and higher latent heat of 54.66 J/g/55.63 J/g;(2)the diatom mud can control the humidity of confined space with a certain volume;(3)the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity.The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency. 展开更多
关键词 thermal storage humidity control phase change material PARAFFIN expanded perlite diatom mud
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Property changes of anchor grout calcined ginger nuts admixed with fly ash and quartz sand after accelerated ageing tests 被引量:4
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作者 ZHANG Jing-ke ZHANG Li-xiang +3 位作者 ZHAO Lin-yi LIU Dun GUO Qing-lin PEI Qiang-qiang 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第11期3114-3125,共12页
Calcined ginger nuts admixed by fly ash and quartz sand(CGN-(F+S))has been validated to be basically compatible to earthen sites as an anchor grout.Accelerated ageing tests including water stability test,temperature a... Calcined ginger nuts admixed by fly ash and quartz sand(CGN-(F+S))has been validated to be basically compatible to earthen sites as an anchor grout.Accelerated ageing tests including water stability test,temperature and humidity cycling test,soundness test and alkali resistance test are conducted with the objective to further research the property changes of CGN-(F+S)grout.Density,surface hardness,water penetration capacity,water permeability capacity,soluble salt,scanning electron microscopy(SEM)images and energy dispersive spectrometry(EDS)spectrum of these samples have been tested after accelerated ageing tests.The results show that densities of samples decrease,surface hardness,water penetration capacity and water permeability capacity of samples increase generally.Besides,soluble salt analysis,SEM and EDS results well corroborate the changes.Based on the results it can be concluded that property changes are most serious after temperature and humidity cycling test,followed by water stability,soundness and alkali resistance test in sequence.But in general,CGN-(F+S)still has good durability. 展开更多
关键词 CGN-(F+S)grout accelerated ageing tests physical property change chemical property change scanning electron microscopy energy dispersive spectrometry
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Land-use Change and Ecological Footprint Analysis of Harbin City 被引量:1
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作者 SUN Lina YUAN Zhaohua SONG Ge 《Journal of Northeast Agricultural University(English Edition)》 CAS 2010年第1期32-36,共5页
Appraisaling the land-use change degree of urban land objectively, analyzing the reasons, and proposing the countermeasures have important meanings to promote land sustainable development. The article analyzed the dyn... Appraisaling the land-use change degree of urban land objectively, analyzing the reasons, and proposing the countermeasures have important meanings to promote land sustainable development. The article analyzed the dynamic change of land-use ecological footprint in Harbin City from 1996 to 2006. Through the measurement of ecological footprint to assess the social impact and the extent of sustainable land-use. The results showed that the per capita ecological footprint in Harbin had increased year by year, while the per capita ecological carrying capacity had decreased, the per capita ecological deficit was increasing, and land-use in Harbin City was in an overload status. Finally, reasonable land-use proposals were proposed. 展开更多
关键词 Harbin City land-use change ecological footprint
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Fabrication, property characterization and thermal performance of composite phase change material plates based on tetradecanol-myristic acid binary eutectic mixture/expanded perlite and expanded vermiculite for building application 被引量:7
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作者 YANG Hua CHEN Wan-he +1 位作者 KONG Xiang-fei RONG Xian 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第9期2578-2595,共18页
A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum ... A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum adsorption roller to prepare phase change material(PCM)particle(PCP).Then EP and EVMT-based composite PCM plates were respectively fabricated through a mold pressing method.The thermal property,chemical stability,microstructure and durability were characterized by differential scanning calorimeter(DSC),Fourier transform infrared spectroscope(FT-IR),scanning electron microscope(SEM)and thermal cycling tests,respectively.The results show that both PCPs have high latent heats with 110 J/g for EP-based PCP and more than 130 J/g for EVMT-based PCP,compact microstructure without PCM leakage,stable chemical property and good durability.The research results have proved the feasibility for the vacuum adsorption roller used in the composite PCM fabrication.Results of thermal storage performance experiment indicate that the fabricated PCM plates have better thermal inertia than common building materials,and the thermal storage performance of PCM plates has nonlinearly changed with outside air velocity and temperature increase.Therefore,PCM plates show a significant potential for the practical application of building thermal storage. 展开更多
关键词 thermal storage phase change material expanded perlite expanded vermiculite binary eutectic mixture
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Numerical simulation of freezing effect and tool change of shield machine with a frozen cutterhead 被引量:6
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作者 DAI Wei XIA Yi-min +1 位作者 XU Hai-liang YANG Mei 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第4期1262-1272,共11页
A shield machine with freezing function is proposed in order to realize tool change operation at atmospheric pressure. Furthermore, the transformation project of freezing cutterhead and tool change maintenance method ... A shield machine with freezing function is proposed in order to realize tool change operation at atmospheric pressure. Furthermore, the transformation project of freezing cutterhead and tool change maintenance method are put forward. Taking the shield construction of Huanxi Power Tunnel as an example, a numerical analysis of the freezing cutter head of the project was carried out. The results show that when the brine temperature is-25 °C, after 30 d of freezing, the thickness of the frozen wall can reach 0.67 m and the average temperature drops to-9.9 °C. When the brine temperature is-30 °C, after 50 d of freezing, the thickness of the frozen wall can reach 1.01 m and the average temperature drops to-12.4 °C. If the thickness of the frozen wall is 0.5 m and the average temperature is-10 °C, as the design index of the frozen wall, the brine temperature should be lower than-28 °C to meet the excavation requirements in 30 d. Analyzing the frozen wall stress under 0.5 m thickness and-10 °C average temperature condition, the tensile safety factor and compressive safety factor are both greater than 2 at the most dangerous position, which can meet the tool change requirements for shield construction. 展开更多
关键词 shield machine CONSTRUCTION frozen cutterhead tool change maintenance finite element simulation
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Preparation of Paraffin/γ-Al2O3 Composites as Phase Change Energy Storage Materials 被引量:1
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作者 赵亮 《沈阳建筑大学学报(自然科学版)》 CAS 北大核心 2011年第5期921-924,951,共5页
Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for t... Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for thermal energy storage,and γ-Al2O3 acted as supporting materials.Characterizations were conducted to evaluate the energy storage performance of the composites,and differential scanning calorimeter results showed that the PCM-3 composite has melting latent heat of 112.9 kJ/kg with a melting temperature of 62.9 ℃.Due to strong capillary force and surface tension between paraffin and γ-Al2O3,the leakage of melted paraffin from the composites can be effectively prevented.Therefore,the paraffin/γ-Al2O3 composites have a good thermal stability and can be used repeatedly. 展开更多
关键词 phase change material thermal energy storage Γ-AL2O3 PARAFFIN
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