Controllable thermal rectification design for buildings based on phase change composites

Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device level,which results in a gap to real applications.Here,we propose a controllable thermal rectification design towards building applications through the direct adhesion of composite thermal rectification material(TRM)based on PCM and reduced graphene oxide(rGO)aerogel to ordinary concrete walls(CWs).The design is evaluated in detail by combining experiments and finite element analysis.It is found that,TRM can regulate the temperature difference on both sides of the TRM/CWs system by thermal rectification.The difference in two directions reaches to 13.8 K at the heat flow of 80 W/m^(2).In addition,the larger the change of thermal conductivity before and after phase change of TRM is,the more effective it is for regulating temperature difference in two directions.The stated technology has a wide range of applications for the thermal energy control in buildings with specific temperature requirements.

Lubrication Performance of Connecting-Rod and Main Bearing in Di erent Engine Operating Conditions

Only the lubrication performance at rated engine operating condition was generally analyzed in current design and research of engine connecting-rod and main bearing. However, the actual engine(especially vehicle engine) does not always operate in rated operating condition and its operating condition changes constantly. In this paper, a fourstroke four-cylinder engine is taken as the studying object, the load and lubrication of connecting-rod and main bearing in di erent operating conditions are analyzed. The load of connecting-rod bearing is calculated by the dynamic calculation method, the loads of all main bearings are calculated by the whole crankshaft beam-element finite element method, and the lubrication performance of connecting-rod and main bearings are analyzed by the dynamic method. The results show that there are major di erences in the changes and numerical value at corresponding moment of the loads and lubrication performance of connecting-rod and main bearings in an engine operating cycle in di erent engine operating conditions; the most unfavorable case of the lubrication performance of connectingrod and main bearings may not take place in the rated engine operating condition. There are also major di erences between the lubrication performance of connecting-rod bearing and that of main bearing and between the lubrication performances of main bearings one another. Therefore, it will not be reasonable that the lubrication performance of a certain connecting-rod bearing or main bearing is analyzed in the design of the engine bearing. It is necessary to analyze simultaneously the lubrication performances of all bearings in di erent engine operating conditions.

Identification Model for Needy Undergraduates Based on FFM

In recent years, as the enrollment rate of Chinese colleges has increased year by year, the identification of needy undergraduates has become increasingly important. However, the traditional way to identify college students with financial difficulties mainly relies on manual review and collective voting, which easily causes subjectivity and randomness. To alleviate the problem above, this paper establishes an automatic identification model for needy undergraduates based on the 1842 questionnaires collected from undergraduates in WHUT. Firstly, this paper filters the questionnaire preliminary using the local outlier factor algorithm. Secondly, this paper combines mutual information, Spearman rank correlation coefficient and distance correlation coefficient by rank-sum ratio to select features for eliminating noise from irrelevant features. Thirdly, this paper trains filed-aware factor machine model and compares it with other models, such as Logistic Regression, SVM, etc. Eventually, this paper finds that filed-aware factor machine performers much better than other models in the identification of needy undergraduates, and prominent features affecting the identification of needy undergraduates are the year of the family income, cost of living provided parents, etc.

Comparative metabolomics analysis of unique yellow hawthorn(Crataegus pinnatifida)and red-skinned cultivars reveals a different polyphenol biosynthesis flux and antioxidative and antidiabetic potential

Objectives:This paper aims to investigate the polyphenol metabolite variation and bioactivities of different-colored hawthorn berries(Crataegus pinnatifida).Materials and Methods:Comparative metabolomics analysis between peel and flesh of yellow hawthorn'Jinruyi'(JRY)and red-skinned ones was carried out by UPLC-MS/MS.Antioxidant activities andα-glucosidase inhibition capacity were also tested among different colored hawthorn samples.Results:A total of 453 polyphenols was characterized,among which phenolic acids and flavonoids were abundant,and were closely relevant to the antioxidant capacity of hawthorn fruits.Polyphenol profile showed accession-specific accumulation in peel or flesh of different colored hawthorn.The unique yellow hawthorn was found to have few anthocyanins but showed enhanced flux to synthesize flavones and flavonols,especially flavone C-glycosides and acylated flavonol glycosides.The specific acylation decoration included acetylation,p-coumaroylation,and malonylation.In addition,yellow hawthorn showed excellentα-glucosidase inhibitory effect,which might be associated with the high concentration of 8 polyphenols including 5 phenolic acids,2 flavone C-glycosides,and an acylated flavonol glycoside,namely,quercetin-7-O-(6ʹʹ-malonyl)glucoside.Such acylated flavonol showed the strongest correlation with the inhibition effect of hawthorn fruits onα-glucosidase,and was predicted to have the lowest binding energy with the enzyme according to molecular docking analysis,indicating its great potential as a strongα-glucosidase inhibitor and an important antidiabetic ingredient in yellow hawthorn.Conclusions:The acylated flavonol glycosides and C-glycosyl flavones might be chemotaxonomic markers differentiating varieties and bioactivities of yellow hawthorn from the traditional red-skinned ones.These findings complement the existing knowledge on the metabolite composition and nutritional properties of hawthorn fruits.