HSPM:A Better Model to Effectively Preventing Open-Source Projects from Dying

With the rapid development of Open-Source(OS),more and more software projects are maintained and developed in the form of OS.These Open-Source projects depend on and influence each other,gradually forming a huge OS project network,namely an Open-Source Software ECOsystem(OSSECO).Unfortunately,not all OS projects in the open-source ecosystem can be healthy and stable in the long term,and more projects will go from active to inactive and gradually die.In a tightly connected ecosystem,the death of one project can potentially cause the collapse of the entire ecosystem network.How can we effectively prevent such situations from happening?In this paper,we first identify the basic project characteristics that affect the survival of OS projects at both project and ecosystem levels through the proportional hazards model.Then,we utilize graph convolutional networks based on the ecosystem network to extract the ecosystem environment characteristics of OS projects.Finally,we fuse basic project characteristics and environmental project characteristics and construct a Hybrid Structured Prediction Model(HSPM)to predict the OS project survival state.The experimental results show that HSPM significantly improved compared to the traditional prediction model.Our work can substantially assist OS project managers in maintaining their projects’health.It can also provide an essential reference for developers when choosing the right open-source project for their production activities.

Regulatable pervaporation performance of Zn-MOFs/polydimethylsiloxane mixed matrix pervaporation membranes

Pervaporation(PV)is an emerging separation technique for liquid mixture.Mixed matrix membranes(MMMs)often demonstrate trade-off relationship between separation factor and flux.In this study,by changing the organic linkers(2-methyl imidazolate,imidazole-2-carboxaldehyde,2-ethyl imidazolate),ZIF-8,ZIF-90 and MAF-6 were prepared and filled in polydimethylsiloxane(PDMS)membranes for dealcoholization of 5%(mass)n-butanol solution,and the membranes properties and pervaporation performances were adjusted.Compared with the pure PDMS membrane,the addition of ZIF-8 resulted in a 9%increase in flux(1136 g·m^(-2)·h^(-1))and a 22.5%increase in separation factor(28.3),displaying antitrade-off effect.For the MAF-6/PDMS MMMs(2.0%mass loading),the pervaporation separation index(PSI)and separation factor were 32347 g·m^(-2)·h^(-1) and 58.6 respectively(increased by 34%and 154%in contrast with that of the pure PDMS membrane),and the corresponding permeation flux was 552 g·m^(-2)·h^(-1),presenting great potential in the removal butanol from water.It was deduced that the large aperture size combined with moderate hydrophobicity of metal–organic frameworks(MOFs)favor the concurrent increase in permeability and selectivity.

Microwave awakening the n-π^(*) electronic transition in highly crystalline polymeric carbon nitride nanosheets for photocatalytic hydrogen generation

The n-π^(*) electronic transition in polymeric carbon nitride(PCN)can remarkably harvest visible light,which thus potentially promotes the photocatalytic hydrogen H2 generation.However,awaking the n-π^(*) lectronic transition has proven to be a grand challenge.Herein,we reported on the awakening of n-π^(*) electronic transition by microwave thermolysis of urea pellet,which yielded the PCN with absorption edge of 600 nm,near 140 nm red-shift from 460 nm of pristine PCN.The n-π^(*) electronic transition endows PCN with an increased photocata lytic H_(2) generation,with a highest H_(2) rate of 61.7μmol h^(-1) under visible light exposure,which is near 6 times higher than that by using the PCN from the thermolysis of urea pellets in an electric furnace(10.6μmol h^(-1)).Furthermore,the n-π^(*) transition in PCN leads to the longest wavelength of 535 nm that can initiate H2 generation,remarkably longer than the absorption edge of pristine PCN(460 nm).This work manifests the advantages of microwave sintering route to awaken the n-π^(*) electronic transition in PCN for an increased photocata lytic performance.

光催化还原杂环化共价有机框架构筑富电子吸附剂实现碘的理想吸附

碘的理想吸附剂通常需要具有两个特征,即高的吸附容量和快的吸附速率,但是这项课题仍然富有挑战性.本文通过构筑杂环化共价有机框架,阐述了一种有效构筑理想碘吸附剂的方法.这种杂环化基于一种后修饰的方式,采用了一种原位光催化双键与邻氨基苯甲酰胺成环的技术.基于该方法得到的材料ECUT-COF-13具有高的碘吸附容量(10.81 g g^(-1),高于所有报道的碘吸附材料)和吸附速率(1.4 g h^(-1),高于所有报导的二维共价有机框架材料).该材料优异的碘吸附性能是基于一种富电子机理,这种富电子状态主要来源于光催化还原杂环化共价有机框架(同时提高了网格的共轭性和氮含量).该研究成果不仅提供了一种构筑功能共价有机框架的新路径,同时提供了一种构筑富电子共价有机框架结构的通用策略.

Unbalanced variation after assembly and double-speed influence coefficient method in the threshing drum

Though the component of threshing drum is pre-balancing on the factory,the drum after assembly still has the problem of unbalanced vibration.In this study,the unbalance mechanism produced by assembly are introduced and the centroid propagation model in the series rotation system was established.The influence of the eccentricity and assembly phase on the assembly unbalance was studied.It is shown that there was a superposition effect between the initial centroid eccentricity caused by the machining error and the centroid eccentricity caused by assembly error,the unbalance amount under the in-phase assembly was larger than that of the anti-phase assembly.Moreover,the unbalance variation was experimentally investigated using in-field balancing detection on the test rig and combine harvester.The experiment results showed the excellent vibration reduction effect of in-field balancing,which showed a reduction of 83.0%and 85.8%.In order to increase the range of in-field balance detection and reduce the calculation error,the double-speed influence coefficient method was proposed.The proposed method adopted the way of first low-speed pre-balancing,and then high-speed precision balance,taking advantage of vibration information at two speeds and avoids nonlinear vibration conditions caused by high unbalanced vibration.Finally,the double-speed influence coefficient method was verified on the test rig.The vibration reduction effect of proposed method was better than the traditional method.

Solid-state NMR reveals that oxygen tri-clusters make glass highly crackresistant

In a recent paper,advanced solid-state nuclear magnetic resonance(SSNMR)technology was employed to reveal the underlying mechanism contributing to the high hardness and exceptional resistance to fragmentation observed in certain special glasses[1].This study utilized SSNMR to analyze the atomic-scale internal structure of glass,enabling the quantification of the fraction of three-coordinated oxygen([^((3))O]).The research findings demonstrate a quantitative relationship between[^((3))O]and the resistance of glass to crack initiation.

生物复杂环境下的核磁共振技术和应用:机遇与挑战并存

核磁共振(nuclear magnetic resonance, NMR)技术是研究生物大分子结构、动力学和相互作用最理想的工具之一.近年来,高场NMR波谱仪的使用和NMR实验方法的不断创新,在很大程度上提高了NMR技术检测的灵敏度和分辨率,使NMR技术得到快速发展和广泛应用.目前,生命科学与物质科学的交叉融合使生命科学研究从观察、描述性科学转向定量、可预测性科学,多种学科交叉渗透发展已成为科学研究领域十分普遍的现象.在这种趋势下,生物复杂环境下的磁共振谱学研究体系日趋成熟,本文重点回顾和讨论了多学科交叉研究趋势下NMR技术在生物复杂体系中的应用和发展,主要包括复杂膜环境下的膜蛋白研究、复杂细胞环境下的细胞内NMR(in-cell NMR)研究以及骨组织的固体NMR研究等.

Unified calculation method and its application in determining the uniaxial mechanical properties of concrete

This paper presents a unified calculation method and its application in determining the uniaxial mechanical properties of concrete with concrete strengths ranging from 10 to 140MPa.By analyzing a large collection of test results of the uniaxial mechanicalproperties of normal-strength,high-strength and super high-strength concrete in China and performing a regression analysis,unified calculation formulas for the mechanical indexes of concrete are proposed that can be applied to various grades of concrete for determining the size coefficient,uniaxial compressive strength,uniaxial tensile strength,elastic modulus,and strain at peak uniaxial compression and tension.Optimized mathematical equations for the nonlinear stress-strain relationship of concrete,including the ascending and descending branches.under uniaxial stress,are also established.The elastic modulus is almost constant throughout the elastic stage for the ascending branches of the stress-strain relationship for concrete.The proposed stress-strain relationship of concrete was applied to the nonlinear finite element analysis of both a steel-concrete composite beam and a concrete-filled steel tubular stub column.The analytical results are in good agreement with the experiment results,indicating that the proposed stress-strain relationship of concrete is applicable.The achievements presented in this paper can be used as references for the design and nonlinear finite element analysis of concrete structures.

Application of an efficient stochastic calculation method on the seismic analysis of an isolated structure

An isolated structure often possesses distinct non-proportional damping characteristics.However,traditional seismic calculation theory and methods are derived based on the assumption that damping is proportional.Based on this drawback,a new,more efficient stochastic calculation method,an improvement on the pseudo-excitation method,is introduced.This method is then applied to the seismic analysis of an isolated structure.By comparing it with the forced decoupling,matrix inversion and iteration methods,it is shown that the presented method can produce accurate results while increasing the efficiency of the stochastic analysis.Moreover,the calculation process of the seismic response of an isolated structure is convergent.Based on the results of the example presented in this paper,the given method is applicable to the seismic analysis of an isolated structure and can be utilized in practice.