High temperature tensile,compression and creep behavior of recycled short carbon fibre reinforced AZ91 magnesium alloy fabricated by a high shearing dispersion technique

The present study seeks the feasibility of using short carbon fibres recycled from polymer matrix composites as alternative to virgin carbon fibres in the reinforcement of magnesium alloys.The microstructures,high temperature mechanical and creep properties of AZ91 alloy and its composites with various recycled carbon fibre contents(2.5 and 5 wt.%)and lengths(100 and 500μm)were investigated in the temperature range of 25-200℃.The microstructural characterization showed that the high shear dispersion technique provided the cast composites with finer grains and relatively homogenous distribution of fibres.The materials tested displayed different behaviour depending on the type of loading.In general,while enhancements in the mechanical properties of composites is attributed to the load bearing and grain refinement effects of fibres,the fluctuations in the properties were discussed on the basis of porosity formation,relatively high reinforcement content leading to fibre clustering and interlayer found between the matrix and reinforcement compared to those of AZ91 alloy.The compressive creep tests revealed similar or higher minimum creep rates in the recycled carbon fibre reinforced AZ91 in comparison to the unreinforced AZ91.

Symbolic Computations and Exact and Explicit Solutions of Some Nonlinear Evolution Equations in Mathematical Physics

With the aid of symbolic computation system Mathematica, several explicit solutions for Fisher＇s equation and CKdV equation are constructed by utilizing an auxiliary equation method, the so called G′/G-expansion method, where the new and more general forms of solutions are also constructed. When the parameters are taken as special values, the previously known solutions are recovered.

Exact solution and dynamic buckling analysis of a beam-column system having the elliptic type loading

This paper presents a closed form solution to the dynamic stability problem of a beam-column system with hinged ends loaded by an axial periodically time-varying compressive force of an elliptic type,i.e.,a1cn 2（τ,k 2）＋a2sn 2（τ,k 2）＋a3dn 2（τ,k 2）.The solution to the governing equation is obtained in the form of Fourier sine series.The resulting ordinary differential equation is solved analytically.Finding the exact analytical solutions to the dynamic buckling problems is difficult.However,the availability of exact solutions can provide adequate understanding for the physical characteristics of the system.In this study,the frequency-response characteristics of the system,the effects of the static load,the driving forces,and the frequency ratio on the critical buckling load are also investigated.

Influence of recycled carbon fiber addition on the microstructure and creep response of extruded AZ91 magnesium alloy

In this study,the recycled short carbon fiber(CF)-reinforced magnesium matrix composites were fabricated using a combination of stir casting and hot extrusion.The objective was to investigate the impact of CF content(2.5 and 5.0 wt.%)and fiber length(100 and 500μm)on the microstructure,mechanical properties,and creep behavior of AZ91 alloy matrix.The microstructural analysis revealed that the CFs aligned in the extrusion direction resulted in grain and intermetallic refinement within the alloy.In comparison to the unreinforced AZ91 alloy,the composites with 2.5 wt.%CF exhibited an increase in hardness by 16-20%and yield strength by 5-15%,depending on the fiber length,while experiencing a reduction in ductility.When the reinforcement content was increased from 2.5 to 5.0 wt.%,strength values exhibited fluctuations and decline,accompanied by decreased ductility.These divergent outcomes were discussed in relation to fiber length,clustering tendency due to higher reinforcement content,and the presence of interfacial products with micro-cracks at the CF-matrix interface.Tensile creep tests indicated that CFs did not enhance the creep resistance of extruded AZ91 alloy,suggesting that grain boundary sliding is likely the dominant deformation mechanism during creep.

ON THE STABILITY OF THE RESIDUAL-FREE BUBBLES FOR THE NAVIER-STOKES EQUATIONS

This paper considers the Calerkin finite element method for the incompressible Navier-Stokes equations in two dimensions, where the finite-dimensional spaces employed consist of piecewise polynomials enriched with residual-free bubble （RFB） functions. The stability features of the residual-free bubble functions for the linearized Navier-Stokes equations are analyzed in this work. It is shown that the enrichment of the velocity space by bubble functions stabilizes the numerical method for any value of the viscosity parameter for triangular elements and for values of the viscosity parameter in the vanishing limit case for quadrilateral elements.

Analysis of EST-SSRs in silver birch(Betula pendula Roth.)

Simple sequence repeats（SSRs） defined as sequence repeat units between 1 and 6 bp occur abundantly in both coding and non-coding regions in eukaryotic genomes and these repeats can affect gene expression. In this study, ESTs（expressed sequence tags） of Betula pendula（silver birch） were analyzed for in silico mining of ESTSSRs, protein annotation, open reading frames（ORFs）,designing primers, and identifying codon repetitions. In B.pendula, the frequency of ESTs containing SSRs was 7.8 %with an average of 1SSR/4. 78 kb of EST sequences. A total of 188 SSRs was identified by using MISA software and dinucleotide SSR motifs（65.9 %） were found to be the most abundant type of repeat motif followed by tri-（27.1 %）,tetra-（4.8 %）, and penta-（2.2 %） motifs. Based on ORF analysis, 175 of 178 sequences were predicted as ORFs and the most frequent SSRs were detected in 50 UTR（58.43 %）,followed by in ORF（31.46 %） and in 30UTR（8.43 %）. 102 of 178 ESTs were annotated as ribosomal protein, transport protein, membrane protein, carrier protein, binding protein,and transferase protein. For a total of 102 SSRs（57.3 %）with significant matches, a set of 102 primers（100 %） with forward and reverse strands was designed by using Primer 3 software. Serine（Ser, 19.6 %） was predominant in putative encoded amino acids and most of amino acids showed nonpolar（35.3 %） nature. Our data provide resources for B.pendula and can be useful for in silico comparative analyses of Betulaceae species, including SSR mining.

Strain tunable band structure of a new 2D carbon allotrope C568

Recently,C568 has emerged as a new carbon allotrope,which shows semiconducting properties with a band gap around 1 eV and has attracted much attention.In this work,the external strain effects on the electronic properties of C568 have been studied theoretically through first-principle calculations.The numerical results show that while in-plane uniaxial and biaxial strains both reduces the band gap of C568 in case of tensile strain,their effects are quite different in the case of compressive strain.With increasing compressive uniaxial strain,the band gap of C568 first increases,and then dramatically decreases.In contrast,the application of compressive biaxial strain up to -10% only leads to a slight increase of band gap.Moreover,an indirect-todirect gap transition can be realized under both types of compressive strain.The results also show that the optical anisotropy of C568 can be induced under uniaxial strain,while biaxial strain does not cause such an effect.These results indicate good strain tunability of the band structure of C568,which could be helpful for the design and optimization of C568-based nanodevices.

THE IMPLEMENTATION MODEL OF INTEGRATING THE THREE SUSTAINABILITY ASPECTS INTO THE UNDERGRADUATE ARCHITECTURAL DESIGN STUDIO

The concept of sustainability in design is meant to ensure that the product of the design is in harmony with humans and nature by taking into consideration the three aspects of sustainability:environmental,social and economic.The objective of this experiment was to integrate the three aspects of sustainability principles into the architectural design studio to train future architects to be able to design sustainable buildings.The study aimed to create an integration method that could be validated through the junior students’work in the innovative Sustainable Architecture Design Studio(SADS)at Izmir Institute of Technology.The impact of the pedagogy on the students’ability to integrate sustainable design principles into their projects was measured through the evaluation tools formulated for this purpose by the instructor.Further,the students’feedback through course evaluation,questionnaire,and col-loquium at the end of the term was used to assess the method.The findings of this research demonstrated that the innovative studio pedagogy and teaching method were successful in integrating the sustainable design elements into design studio projects,while the level of sustainable elements integration was 68%.

INCORPORATING SUSTAINABILITY PRINCIPLES INTO ARCHITECTURAL DESIGN EDUCATION:RESULTS OF AN EXPERIMENTAL DESIGN STUDIO

Design is a structured process or a tactical guideline to accomplish a unique expectation of a product, while a design studio is the environment where students are taught the skills to design the product, which may be a building. Hence, the design studio course is the most important component of the architectural education curriculum;it is where the students get an opportunity to apply the theoretical knowledge gained through lecture-based courses. Yet most theory is not put into practice;consequently, the principles of sustainable design solutions are developed. There is an urgent need to teach future architects how to integrate sustainable design principles into their projects in order to prevent or mitigate environmental degradation due to the negative impacts of building projects. This experimental study initiated a new design studio pedagogy and a novel teaching structure for integrating sustainability principles into the architectural design projects of 3rd year students. It also evolved a testing method to assess the success of the new pedagogy and the students’ final design projects. This paper presents the results of the experimental design studio and delivers recommendations for subsequent sustainable design studio courses.

钙华非经典沉积的纳米生长过程与调控机制初探——以九寨沟—黄龙钙华形成为例

钙华是自然界重要的岩溶碳酸盐沉淀之一,其形成过程往往受到生命活动的影响,弄清钙华生物沉积作用有助于更好地理解钙华微岩相结构和地球化学特征的气候环境指示意义。本文以黄龙-九寨沟钙华形成为例,阐述黄龙-九寨沟现代钙华纳米结晶特征、纳米钙华的生长和集合体形态,分析模拟实验中生物有机质对钙华生长和形貌的调控原因,揭示了生物活动和代谢产物对纳米钙华成核、生长及钙华晶体形貌的调控两途径四阶段机制;为探究钙华成因、碳酸钙生长调控机制、钙华退化的因素及其保护和可持续利用钙华景观具有重要的科学价值。

钙华体次生有机体系的界面结晶作用研究

本文总结了钙华体次生有机体系中生物群落特征和界面结晶行为,根据生物在碳酸盐沉积中的角色,将钙华体中次生有机体系的界面结晶矿化类型分为生物控制矿化沉积和生物诱导矿化沉积。分述了碳酸钙沉积矿化相关的五种生物代谢活动,讨论了生物胞外聚合物(EPS)对碳酸钙矿物晶型和形貌的影响。针对目前钙华研究中存在的问题,今后应深入研究生物体主要构成元素、生物小分子和生物体内部组织在钙华形成或退化中的作用,进一步厘清钙华体与次生有机体系的多界面溶化方式,为钙华保护修复及钙华退化治理措施提供科学依据。

Sequence Motif-Based One-Class Classifiers Can Achieve Comparable Accuracy to Two-Class Learners for Plant microRNA Detection

microRNAs (miRNAs) are short nucleotide sequences expressed by a genome that are involved in post transcriptional modulation of gene expression. Since miRNAs need to be co-expressed with their target mRNA to observe an effect and since miRNAs and target interactions can be cooperative, it is currently not possible to develop a comprehensive experimental atlas of miRNAs and their targets. To overcome this limitation, machine learning has been applied to miRNA detection. In general binary learning (two-class) approaches are applied to miRNA discovery. These learners consider both positive (miRNA) and negative (non-miRNA) examples during the training process. One-class classifiers, on the other hand, use only the information for the target class (miRNA). The one-class approach in machine learning is gradually receiving more attention particularly for solving problems where the negative class is not well defined. This is especially true for miRNAs where the positive class can be experimentally confirmed relatively easy, but where it is not currently possible to call any part of a genome a non-miRNA. To do that, it should be co-expressed with all other possible transcripts of the genome, which currently is a futile endeavor. For machine learning, miRNAs need to be transformed into a feature vector and some currently used features like minimum free energy vary widely in the case of plant miRNAs. In this study it was our aim to analyze different methods applying one-class approaches and the effectiveness of motif-based features for prediction of plant miRNA genes. We show that the application of these one-class classifiers is promising and useful for this kind of problem which relies only on sequence- based features such as k-mers and motifs comparing to the results from two-class classification. In some cases the results of one-class are, to our surprise, more accurate than results from two-class classifiers.

A New Approach to Extensible Continuum Robot Control Using the Sliding-Mode

In this paper, the authors present a new control strategy for continuous backbone （continuum） ＂trunk and tentacle＂ robots. Control of this emerging new class of robots has proved difficult due to the inherent complexity of their dynamics. Using a recently established full dynamic model, the authors introduce a new nonlinear model-based control strategy for continuum robots. The approach is applicable to continuum robots which can extend/contract as well as bend throughout their structure. Results are illustrated using the mathematical model of a three-section, six-degree of freedom planar continuum robot.

Accurate Plant MicroRNA Prediction Can Be Achieved Using Sequence Motif Features

MicroRNAs (miRNAs) are short (~21 nt) nucleotide sequences that are either co-transcribed during the production of mRNA or are organized in intergenic regions transcribed by RNA polymerase II. In animals, Drosha, and in plants DCL1 recognize pre-miRNAs which set themselves apart by their characteristic stem loop (hairpin) structure. This structure appears important for their recognition during the process of maturation leading to functioning mature miRNAs. A large body of research is available for computational pre-miRNA detection in animals, but less within the plant kingdom. For the prediction of pre-miRNAs, usually machine learning approaches are employed. Therefore, it is necessary to convert the pre-miRNAs into a set of features that can be calculated and many such features have been described. We here select a subset of the previously described features and add sequence motifs as new features. The resulting model which we called MotifmiRNAPred was tested on known pre-miRNAs listed in miRBase and its accuracy was compared to existing approaches in the field. With an accuracy of 99.95% for the generalized plant model, it distinguishes itself from previously published results which reach an average accuracy between 74% and 98%. We believe that our approach is useful for prediction of pre-miRNAs in plants without per species adjustment.

Some Remarks on Exp-Function Method and Its Applications

Recently, many important nonlinear partial differential equations arising in the applied physical and mathematical sciences have been tackled by a popular approach, the so-called Exp-function method. In this paper, we present some shortcomings of this method by analyzing the results of recently published papers. We also discuss the possible improvement of the effectiveness of the method.

Continuous flow pyrolysis of virgin and waste polyolefins:a comparative study,process optimization and product characterization

Under optimal process conditions,pyrolysis of polyolefins can yield ca.90 wt%of liquid product,i.e.,combination of light oil fraction and heavier wax.In this work,the experimental findings reported in a selected group of publications concerning the non-catalytic pyrolysis of polyolefins were collected,reviewed,and compared with the ones obtained in a continuously operated bench-scale pyrolysis reactor.Optimized process parameters were used for the pyrolysis of waste and virgin counterparts of high-density polyethylene,low-density polyethylene,polypropylene and a defined mixture of those(i.e.,25:25:50 wt%,respectively).To mitigate temperature drops and enhance heat transfer,an increased feed intake is employed to create a hot melt plastic pool.With 1.5 g·min^(-1) feed intake,1.1 L·min^(-1) nitrogen flow rate,and a moderate pyrolysis temperature of 450℃,the formation of light hydrocarbons was favored,while wax formation was limited for polypropylene-rich mixtures.Pyrolysis of virgin plastics yielded more liquid(maximum 73.3 wt%)than that of waste plastics(maximum 66 wt%).Blending polyethylenes with polypropylene favored the production of liquids and increased the formation of gasoline-range hydrocarbons.Gas products were mainly composed of C3 hydrocarbons,and no hydrogen production was detected due to moderate pyrolysis temperature.

Computational Prediction of Micro RNAs from Toxoplasma gondii Potentially Regulating the Hosts' Gene Expression

MicroRNAs （miRNAs） were discovered two decades ago, yet there is still a great need for further studies elucidating their genesis and targeting in different phyla. Since experimental discovery and validation of miRNAs is difficult, computational predictions are indispensable and today most computational approaches employ machine learning. Toxoplasma gondii, a parasite residing within the cells of its hosts like human, uses miRNAs for its post-transcriptional gene reg- ulation. It may also regulate its hosts＇ gene expression, which has been shown in brain cancer. Since previous studies have shown that overexpressed miRNAs within the host are causal for disease onset, we hypothesized that T. gondii could export miRNAs into its host cell. We computationally predicted all hairpins from the genome of T. gondii and used mouse and human models to filter possible candidates. These were then further compared to known miRNAs in human and rodents and their expression was examined for T. gondii grown in mouse and human hosts, respectively. We found that among the millions of potential hairpins in T. gondii, only a few thousand pass filtering using a human or mouse model and that even fewer of those are expressed. Since they are expressed and differentially expressed in rodents and human, we suggest that there is a chance that T. gondii may export miRNAs into its hosts for direct regulation.

Exploring adoption of augmented reality smart glasses： Applications in the medical industry

This study explores the use of augmented reality smart glasses(ARSGs) by physicians and their adoption of these products in the Turkish medical industry.Google Glass was used as a demonstrative example for the introduction of ARSGs. We proposed an exploratory model based on the technology acceptance model by Davis. Exogenous factors in the model were defined by performing semi-structured in-depth interviews, along with the use of an expert panel in addition to the technology adoption literature. The framework was tested by means of a field study, data was collected via an Internet survey, and path analysis was used. The results indicate that there were a number of factors to be considered in order to understand ARSG adoption by physicians.Usefulness was influenced by ease of use, compatibility,ease of reminding, and speech recognition, while ease of use was affected by ease of learning, ease of medical education, external influence, and privacy. Privacy was the only negative factor that reduced the perceived ease of use,and was found to indirectly create a negative attitude.Compatibility emerged as the most significant external factor for usefulness. Developers of ARSGs should pay attention to healthcare-specific requirements for improved utilization and more extensive adoption of ARSGs in healthcare settings. In particular, they should focus on how to increase the compatibility of ARSGs. Further research needs to be conducted to explain the adoption intention of physicians.

Utilization of psychoacoustic parameters for occupancy-based acoustic evaluation in eating establishments

Psychoacoustic parameters are mostly used for determining the sound quality of mechanical sounds.They have also started to be used for evaluating soundscapes of open areas and enclosed spaces.This research aims to find out the relationship between the psychoacoustic parameters and acoustic comfort in non-acoustic enclosed public spaces,specifically in eating establishments.Both on-site measurements and laboratory listening tests were conducted for five eating establishments.During on-site measurements,a simultaneous questionnaire study was also carried out.Subjective and objective data were comparatively evaluated.Listening tests were based on auralizations with calibrated simulation models.This provided a research model,that allows control over the acoustic environment without having to make real changes in the physical elements of the eating establishments.The auralization sound files were presented to listening test participants with headphones and they evaluated soundscapes with different psychoacoustic properties.As results,better acoustic comfort was found to be related with higher sharpness,lower reverberation time,lower loudness and lower roughness values for the examined parameter ranges.