Experimental Study on the Bearing Characteristics of Rigid-Flexible Long-Short Pile Composite Foundations in Thick Collapsible Loess Areas

Fei Gao,Xuansheng Cheng,Wenfang Wang,Qingfeng Lv,Xiangjun Cheng 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.5

The bearing and deformation characteristics of embankments with rigid-flexible long-short pile composite foundations (RLPCFs) in thick collapsible loess strata are not yet accurately understood. In this study, a large-scale field experiment was conducted, and screw (long) and compaction (short) piles were employed to reinforce a section of the foundation of the Lanzhou-Zhangye high-speed railway in thick collapsible loess. The pile load transfer, foundation settlement, pile-soil stress distribution, and load sharing characteristics were analyzed to reveal the bearing properties of the composite foundation. The results show that negative friction arises along the upper part of the pile, and the neutral points of the short pile and long pile are located at 2/5 and 1/3 down the pile lengths, respectively. The short pile eliminates the collapsibility of the shallow loess and enhances the foundation’s bearing capacity. The long pile transfers the load of the shallow foundation and pile top to the deep foundation through lateral friction, which reduces the settlement of the shallow foundation. When the soil arch in the embankment is fully formed, the short pile bears approximately 20% of the load, while the long pile and the soil between piles bear 80%. With the increase in embankment filling height, the load borne by the long pile rises, and the load borne by the soil between piles decreases gradually. The top settlement of the cross-section of the composite foundation is distributed in a concave basin shape, and the maximum settlement occurs in the center of the embankment. The parameters of the short pile can be obtained on the basis of the collapsibility grade and bearing capacity of the loess foundation, the length and area replacement rate of the long pile can be obtained based on the settlement control requirements of the superstructure of the composite foundation, and the lateral friction of the long pile can be increased by increasing the roughness of the pile and setting the screw.

Prevalence and Risk Factors of Cerebral Small Vessel Disease in a Chinese Population-Based Sample

Fei Han,Fei-Fei Zhai,Quan Wang,Li-Xin Zhou,Jun Ni,Ming Yao,Ming-Li Li,Shu-Yang Zhang,Li-Ying Cui,Zheng-Yu Jin,Yi-Cheng Zhu 대한뇌졸중학회 2018 Journal of stroke Vol.20 No.2

Background and Purpose Epidemiological data of cerebral small vessel disease (CSVD) in the general population of China are lacking. We report on the prevalence of lacunes, white matter hyperintensity (WMH), and cerebral microbleeds (CMBs) in a community-based sample in China and compare the results with those of other studies. Methods This was a cross-sectional analysis of the population-based Shunyi Study in China. A total of 1,211 stroke-free participants (mean age, 55.6±9.3 years; 37.4% men) with available 3 Tesla (3T) magnetic resonance images were included in this analysis. Demographic information and risk factor data were assessed. The overall and age-specific prevalence of lacunes, WMH, and CMBs was evaluated. Associations between cardiovascular risk factors and the presence of these lesions were analyzed by multiple logistic regression. Results Our study showed a prevalence of 14.5% for lacunes, 72.1% for periventricular hyperintensity (PVH), 65.4% for deep white matter hyperintensity (DWMH), and 10.6% for CMBs. When compared with other community-based samples, individuals in the same age group showed a higher burden of lacunes and a relatively lower prevalence of CMBs. Advanced age was independently associated with the prevalence of these CSVD markers, while the presence of hypertension increased the risk of lacunes, PVH/DWMH, and CMBs in deep or infratentorial locations. Conclusions A higher burden of lacunes but a relatively lower prevalence of CMBs was observed in this Chinese population. This notable result highlights the challenge of CSVD prevention in China. Chinese have a risk factor profile for CSVD similar to those in other populations.

Soil fungal communities of montane natural secondary forest types in China

Fei Cheng,Xin Wei,Lin Hou,Zhengchun Shang,Xiaobang Peng,Peng Zhao,Zhaoxue Fei,Shuoxin Zhang 한국미생물학회 2015 The journal of microbiology Vol.53 No.6

Distinctive plant communities may provide specific physical and chemical properties with soils by specific litters and root exudates to exert effects on soil microorganisms. Past logging activities in the Qinling Mountains induced diverse natural secondary forest types (NSFTs). How these recovered NSFTs regulate patterns of soil microbial communities remain limited. In the study, we used terminal-restriction fragment length polymorphism (T-RFLP) to precisely determine forest type-specific soil fungal diversity and composition in five NSFTs. Our results indicated that NSFTs had significant impacts on the soil fungal communities. The most diverse fungal species were found in the Armand pine (Pinus armandi) and Chinese pine (Pinus tabulaeformis) forest soils, followed by sharptooth oak (Quercus aliena var. acuteserrata) and Chinese pine-sharptooth oak forest soils, the wilson spruce (Picea wilsonii) forests had the lowest soil fungal diversity. The analyses of community composition suggested that the fungal communities of Armand pine forest soils were similar to those of Chinese pine forest soils, while other communities prominently differed from each other. Stepwise multiple regression analysis revealed that soil silt, clay, pH, and ammonium nitrogen had intimate linkages with soil fungal diversity. Furthermore, the patterns of soil fungal communites were strongly governed by the specific soil environments of the tested NSFTs, as described by canonical correspondence analysis (CCA). Finally, our study showed that soil fungal communities may be mediated by NSFTs via specific soil edaphic status. Hence, such a comparable study may provide fundamental information for fungal diversity and community structure of natural forests and assist with better prediction and understanding how soil fungal composition and function alter with forest type transformation.

Exploring the Depth and Diversity of Argument Structures in Taiwanese EFL Writing

( Fei Wen Cheng ) 범태평양응용언어학회 2006 범태평양응용언어학회지 Vol.10 No.2

K-doping effect of the superconductivity in K2xFeTe1-xSx (0.07 ≤ x ≤ 0.3)

Cheng Cheng,Zhenjie Feng,Qing Li,Tao Li,Qiang Hou,Fei Chen,Zhongmin Ou,Jun-Yi Ge,Shixun Cao,Jincang Zhang 한국물리학회 2019 Current Applied Physics Vol.19 No.4

Bulk samples of K doping K2xFeTe1-xSx with x=0.07, 0.1, 0.2, 0.3 are successfully prepared by using easy-to-use stable compound K2S as the reactant. The lattice constant calculated from X-ray diffraction patterns indicate that K ions enter the Fe-Te-S layers. K doping is beneficial enhance the superconductivity transition temperature from the R-T curves. The apparent diamagnetic signal is observed in M-T curves when the content of K is smaller than 0.1. However, differential curves (dM/dT) in K-rich samples appear sharp slope mutations, which means that the Meissner effect signal is covered by the increased excess ferromagnetic ions. The number of excess Fe magnetic ions is proportional to K content, which may play an important role in determining the superconductivity.

Audience Strategies Used by EFL College Writers

( Fei Wen Cheng ) 범태평양응용언어학회 2005 범태평양응용언어학회지 Vol.9 No.2

This study examined how two EFL college students represented their audience in the writing process and how they adapted their writing to the assigned audience. The results indicated that the more skilled writer was more capable of analyzing and making inferences of the assigned audience than the less skilled wIiter. Her conceptualizations were also richer and more articulated. Both participants were able to employ a diverse variety of more obvious audience appeals but they were less able to argue from the reader``s viewpoint. Their abilities to conceptualize the assigned audience and utilize this conceptualization were constrained by the school context and their repertoire of rhetorical strategies.

Lightweight Design of CFRP-Laminated Structures by Combining Microscopical Homogenization and Macroscopical Optimization

Cheng Fei,Zheng Chenggong,Liu Yunfei,Zuo Wenjie,Wang Xinzhe,Guo Guikai 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.5

We developed a new method for the design of carbon-fiber reinforced plastic (CFRP)-laminated structures, which combined the asymptotic homogenization method and ply optimization. The equivalent mechanical properties of a single-layer CFRP were calculated using the asymptotic homogenization method. The ply optimization of the laminated structures was divided into three parts: an initial free-size optimization to identify the optimal ply shapes and locations of patches per ply orientation; an optimization of the final size to identify the optimal thicknesses of each ply; and an optimization of the final ply stacking sequence to obtain the optimal stacking sequence. Using the example of the floor of a body-in-white model, our method provided a reasonable optimization result with reduced mass by 60 %. The proposed method provides an efficient way to investigate laminated structures and has potential for lightweight design and analysis of automobile components.

Pyrolytic Conversion of Blended Precursors into Ti-Al-N Ceramic Composites

Cheng, Fei,Sugahara, Yoshiyuki,Kuoda, Kazuyuki The Korean Ceramic Society 2000 The Korean journal of ceramics Vol.6 No.1

Pyrolytic preparations of Ti-Al-N ceramics from three blended precursors were investigated. The precursors were prepared stirring ($HA1N^{i}Pr_m$ and an aminolysis product of $Ti(NMe_2)_4$ with $MeHNCH_2CH_2$NHMe in $C_6/H_6$ . IR and $^1H\;NMR $analyses suggested that essentially no Ti-N-Al bonds were present in the precursors. Pyrolysis of the precursors under $NH_3-N_2$led to the formation of brown solids with ceramic yields of about 30%, and the Ti-Al ratios in the pyrolyzed products were close to those of the precursors. XRD analysis of the pyrolyzed product from the precursor with Ti:Al=5:1 indicated the formation of a NaCl-type compound as the only crystalline phase. Pyrolysis of the precursor with Ti:Al=2:1 led to the formation of AlN besides the major NaCl-type compound. A ceramic composite containing AlN and the NaCl-type compound was formed by pyrolysis of the precursor with Ti:Al=1:2.

Finding Reasons for ESL/EFL Argumentative Writing

Fei-Wen Cheng 아시아영어교육학회 2010 The Journal of Asia TEFL Vol.7 No.1

Task Representation and Text Construction in Reading-to-Write

( Fei Wen Cheng ) 범태평양응용언어학회 2009 범태평양응용언어학회지 Vol.13 No.2

Students` interpretations of their academic writing tasks has been a central concern in the cognitive-based writing research due to the prominent role such decision-making plays in determining students` subsequent thinking and composing strategies and ultimately in shaping their textual quality. Without a comprehensive understanding of how L2 students interpret the writing task, ESL/EFL writing instructors may not know the sources of various writing problems in students` written texts and hence, may not be able to develop appropriate writing pedagogy. The present study attempts to address this research gap by studying the interpretive process of three high ability college seniors as composing a source-based academic assignment. The findings show that all the participants have different representations of the assigned task. Two of them were less able to make sense of the requirements of such a writing task as expected in the academic community and consequently failed to use the assigned readings as required although they did understand the basic format associated with this task type and had received prior instruction on reading-based writing. First language culture may have affected how they constructed the writing task for themselves as inferring and eliciting the information specified in the writing prompt.