• Wind and Structures
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• 제38권4호
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• pp.245-259
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• 2024

In a tornadic wind field, the vertical velocity component in certain regions of tornadoes can be significant, forming one of the major differences between tornadic wind fields and synoptic straight-line wind fields. To better understand the wind characteristics of tornadoes and properly estimate the action of tornadoes on civil structures, it is important to ensure that all the attributes of tornadoes are captured. Although Doppler radars have been used to measure tornadic wind fields, they can only directly provide information on quasi-horizontal velocity. Therefore, lots of numerical simulations and experimental tests in previous research ignored the vertical velocity at the boundary. However, the influence of vertical velocity in tornadic wind fields is not evaluated. To address this research gap, this study is to use an approach to derive the vertical velocity component based on the horizontal velocities extracted from the radar-measured data by mass continuity. This approach will be illustrated by using the radar-measured data of Spencer Tornado as an example. The vertical velocity component is included in the initial inflow condition in the CFD simulation to assess the influence of including vertical velocity in the initial inflow condition on the entire tornadic wind field.

• Advances in nano research
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• 제16권6호
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• pp.615-622
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• 2024

This study investigates the impact of educational management on the performance of scholars in the field of nano/micro-level composites. The objective is to understand how effective management strategies can enhance the academic achievements and research outcomes of students specializing in this advanced area of materials science. Through a combination of qualitative and quantitative methodologies, data was collected from various educational institutions renowned for their programs in nano/micro-level composites. Our results indicate that tailored educational management practices significantly improve student performance. Key strategies identified include personalized mentorship programs, interdisciplinary collaboration opportunities, and access to state-of-the-art laboratory facilities. Institutions that implemented these practices observed a marked increase in the quality and quantity of research outputs, higher student satisfaction rates, and improved post-graduation employment prospects in relevant industries. Furthermore, the study highlights the importance of continuous professional development for educators to stay abreast of the latest advancements in nano/micro-level composites. By fostering an environment of innovation and support, educational management can play a crucial role in shaping the next generation of researchers and professionals in this cutting-edge field. These findings underscore the necessity of strategic educational management in optimizing the academic and professional trajectories of scholars in nano/micro-level composites, ultimately contributing to advancements in technology and industry applications.

• Journal of Microbiology and Biotechnology
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• 제33권11호
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• pp.1495-1505
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• 2023

The western honeybee Apis mellifera L., a vital crop pollinator and producer of honey and royal jelly, faces numerous threats including diseases, chemicals, and mite infestations, causing widespread concern. While extensive research has explored the link between gut microbiota and their hosts. However, the impact of Varroa destructor infestation remains understudied. In this study, we employed massive parallel amplicon sequencing assays to examine the diversity and structure of gut microbial communities in adult bee groups, comparing healthy (NG) and Varroa-infested (VG) samples. Additionally, we analyzed Varroa-infested hives to assess the whole body of larvae. Our results indicated a notable prevalence of the genus Bombella in larvae and the genera Gillamella, unidentified Lactobacillaceae, and Snodgrassella in adult bees. However, no statistically significant difference was observed between NG and VG. Furthermore, our PICRUSt analysis demonstrated distinct KEGG classification patterns between larval and adult bee groups, with larvae displaying a higher abundance of genes involved in cofactor and vitamin production. Notably, despite the complex nature of the honeybee bacterial community, methanogens were found to be present in low abundance in the honeybee microbiota.

• Structural Engineering and Mechanics
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• 제89권3호
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• pp.309-321
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• 2024

In this paper, the effect of semi-rigid connections on the stability bearing capacity of cross-bracings in steel tubular transmission towers is investigated. Herein, a prediction method based on the hybrid model which is a combination of particle swarm optimization (PSO) and backpropagation neural network (BPNN) is proposed to accurately predict the stability bearing capacity of cross-bracings with semi-rigid connections and to efficiently conduct its probabilistic assessment. Firstly, the establishment of the finite element (FE) model of cross-bracings with semi-rigid connections is developed on the basis of the development of the mechanical model. Then, a dataset of 7425 samples generated by the FE model is used to train and test the PSO-BPNN model, and the accuracy of the proposed method is evaluated. Finally, the probabilistic assessment for the stability bearing capacity of cross-bracings with semi-rigid connections is conducted based on the proposed method and the Monte Carlo simulation, in which the geometric and material properties including the outer diameter and thickness of cross-sections and the yield strength of steel are considered as random variables. The results indicate that the proposed method based on the PSO-BPNN model has high accuracy in predicting the stability bearing capacity of cross-bracings with semi-rigid connections. Meanwhile, the semi-rigid connections could enhance the stability bearing capacity of cross-bracings and the reliability of cross-bracings would significantly increase after considering semi-rigid connections.

• Wind and Structures
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• 제38권6호
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• pp.477-492
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• 2024

This study presents a comprehensive investigation of wind load characteristics and wind-induced responses associated with different wind incidence angles and terrains of the 1000kV UHV substation frame. High-frequency force balance (HFFB) force measurement wind tunnel tests are conducted on the overall and segment models to characterize wind loads characteristics such as the aerodynamic force coefficients and the shape factors. The most unfavorable wind incidence angles and terrains for aerodynamic characteristics are obtained. A finite element model of the substation frame is built to determine the wind-induced response characters based on the aerodynamic force coefficients and bottom forces of the segment models. The mean and root mean square (RMS) values of displacement responses at different heights of the frame structure are compared and analyzed. The influence of wind incidence angle and terrains on wind-induced responses is also examined. The displacement responses in terms of the crest factor method are subsequently transformed into dynamic response factors. The recommended values of dynamic response factors at four typical heights have been proposed to provide a reference for the wind resistance design of such structures.

• Steel and Composite Structures
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• 제27권1호
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• pp.75-87
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• 2018

This paper presents a new method to compute the shear strength of composited structural B-C-W members. These B-C-W members, defined as concrete-filled steel box beams, columns and shear walls, consist of a slender rectangular steel plate box filled with concrete and inserted steel plates connecting the two long-side steel plates. These structural elements are intended to be used in structural members of super-tall buildings and nuclear safety-related structures. The concrete confined by the steel plate acts to be in a multi-axial stressed state: therefore, its shear strength was calculated on the basis of a concrete's failure criterion model. The shear strength of the steel plates on the long sides of the structural element was computed using the von Mises plastic strength theory without taking into account the buckling of the steel plate. The spacing and strength of the inserted plates to induce plate yielding before buckling was determined using elastic plate theory. Therefore, a predictive method to compute the shear strength of composited structural B-C-W members without considering the shear span ratio was obtained. A coefficient considering the influence of the shear span ratio was introduced into the formula to compute the anti-lateral bearing capacity of composited structural B-C-W members. Comparisons were made between the numerical results and the test results along with this method to predict the anti-lateral bearing capacity of concrete-filled steel box walls. Nonlinear static analysis of concrete-filled steel box walls was also conducted by using ABAQUS and the results agreed well with the experimental data.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.670-677
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• 2010

An alkaline pectate lyase, Bsp165PelA, was purified to homogeneity from the culture broth of alkaliphilic Bacillus sp. N16-5. The enzyme showed a specific activity as high as 1,000 U/mg and had optimum activity at pH 11.5 and $50^{\circ}C$. It was composed of a single polypeptide chain with a molecular mass of 42 kDa deduced from SDS-PAGE, and its isoelectric point was around pH 6.0. It could efficiently depolymerize polygalacturonate and pectin. Characterization of product formation revealed unsaturated digalacturonate and trigalacturonate as the main products. The pectate lyase gene (pelA) contained an open reading frame (ORF) of 1,089 bp, encoding a 36-amino acids signal peptide and a mature protein of 326 amino acids with a calculated molecular mass of 35.943 Da. The deduced amino acid sequence from the pelA ORF exhibited significant homology to those of known pectate lyases in polysaccharide lyase family 1. Some conserved active-site amino acids were found in the deduced amino acid sequence of Bsp165PelA. $Ca^{2+}$ was not required for activity on pectic substrates.

• 패션비즈니스
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• 제5권5호
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• pp.87-96
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• 2001

The purposes of this study is to supply information on the most common and generalized purchasing conditions of suits in China by surveying male customers from Beijing, Shanghai, Dalian, Tianjin, Harbin and Guangzhou with ages from 20's to 40's. Statistic data from the questionnaire was analyzed by SPSS 10.0 for windows and the analyzing method was processed by descriptive statistics, cross analysis and dispersed analysis and for verifying similarities, t-test and $\chi^2$-test were used. The results could be summarized as follows; First, Purchasing places for suits were stores specializing in men's wear, department stores and reasons for purchasing suits were 'For business' and 'Change of season'. Two, for purchasing information provider, television worked as the key source of providing purchasing information and outdoor advertisement, for main influence of purchasing, the consumers answered that they are the key decision makers and replied their wife or girlfriend's opinion as the answer. Three, for number of suits in possession, answered three suits followed by more than five suits and for the purchasing period, the consumers chose one suit per year or every 6month. Four, according to the questionnaire on prices, colors, fabrics and styles of suits they buy, the consumers pay between 1,000 and 1,999RMB per suit and for the colors, black, dark gray and deep blue. For the choice of fabrics, said pure wool. For the styles of the suits, answered single three buttons. Five, the result from a question on the level of satisfaction shows 'satisfied', 'average' and 'very satisfied' with the purchase.

• Wind and Structures
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• 제26권5호
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• pp.267-277
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• 2018

Numerical simulations are performed of a long flexible cylinder undergoing vortex-induced vibration at a Reynolds number of 500. The cylinder is pinned at both ends, having an aspect ratio of 100 (cylinder length to cylinder diameter) and a mass ratio of 4.2 (structural mass to displaced fluid mass). Temporal and spatial information on the cross-flow (CF) and in-line (IL) vibrations is extracted. High modal vibrations up to the $6^{th}$ in the CF direction and the $11^{th}$ in the IL direction are observed. Both the CF and IL vibrations feature a multi-mode mixed pattern. Mode competition is observed. The $2^{nd}$ mode with a low frequency dominates the IL vibration and its existence is attributed to a wave group propagating back and forth along the span. Distributions of fluid force coefficients are correlated to those of the CF and IL vibrations along the span. Histograms of the x'-y motion phase difference are evaluated from the total simulation time and a complete vibration cycle representing the standing or travelling wave pattern. Correlations between the phase difference and the vibrations are discussed. Vortex structures behind the cylinder show an interwoven near-wake pattern when the standing wave pattern dominates, but an oblique near-wake pattern when the travelling wave pattern prevails.

• Wind and Structures
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• 제26권5호
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• pp.293-304
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• 2018

A numerical study is conducted on the flow characteristics of a rectangular cylinder (chord-to-width ratio C/W = 2 - 10) mounted close to a rigid wall at gap-to-width ratios G/W = 0.25 - 6.25. The effects of G/W and C/W on the Strouhal number, vortex structure, and time-mean drag and lift forces are examined. The results reveal that both G/W and C/W have strong influences on vortex structure, which significantly affects the forces on the cylinder. An increase in G/W leads to four different flow regimes, namely no vortex street flow (G/W < 0.75), single-row vortex street flow ($0.75{\leq}G/W{\leq}1.25$), inverted two-row vortex street flow ($1.25<G/W{\leq}2.5$), and two-row vortex street flow (G/W > 2.5). Both Strouhal number and time-mean drag are more sensitive to C/W than to G/W. For a given G/W, Strouhal number grows with C/W while time-mean drag decays with C/W, the growth and decay being large between C/W = 2 and 4. The time-mean drag is largest in the single-row vortex street regime, contributed by a large pressure on the front surface, regardless of C/W. A higher C/W, in general, leads to a higher time-mean lift. The maximum time-mean lift occurs for C/W = 10 at G/W = 0.75, while the minimum time-mean lift appears for C/W = 2 at the same G/W. The impact of C/W on the time-mean lift is more substantial in single-row vortex regime. The effect of G/W on the time-mean lift is larger at a larger C/W.