Mechanical Performance and Environmental Effect of Coal Fly Ash on MICP-Induced Soil Improvement

Junke Zhang,Peidong Su,Kejun Wen,Yadong Li,Lin Li 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.11

Coal fly ash (FA) is one of the main byproducts of coal burning. Nearly half of FA cannot be reused or recycled. The potential environmental leaching of trace elements in FA may limit its application. Microbially induced carbonate precipitation (MICP) is a promising technology to improve soil properties. This study was to investigate the effect of fly ash in MICP-stabilized soil on its mechanical and environmental impacts. Two kinds of fly ash were considered: FA1 was Class-F fly ash, FA2 was off-specific fly ash. The 0% (sand only), 3%, 6% and 9% content of FA were introduced to FA-sand mixtures to perform MICP process. Triaxial compression test was performed to evaluate the effect of FA content on the development of strength. The triaxial test results indicated that with 3% addition of FA, the peak deviator stress increased significantly. When MICP-treated sand mixed with 3% FA1, the deviator stress increased to 1,959 kPa compared to that of MICP-treated sand only samples of 800 kPa. The peak deviator stress increased by 154% and 115% when the additions of FA1 were 6% and 9%, respectively. The stress increase was caused by the bonding of precipitated CaCO3 in MICP. However, higher content of FA1 (9% or higher) could restrict the activity of bacteria by reducing the void spaces. MICP-treated samples with the addition of FA2 presented a better enhancement in peak stress for its higher CaO content which could lead to additional cementation besides MICP. Leaching tests by toxicity characteristic leaching procedure (TCLP) and sequential extraction tests indicated that there was no potential risk to introduce fly ash into the MICP process during the soil improvement. MICP process resulted to the fraction change of trace metals which could make trace metal more stable. Microscale images at scale of 10 μm, 100 μm and 200 μm have clearly presented the precipitated CaCO3. It showed that large amount of precipitated CaCO3 coated the particle surfaces and filled the void spaces. Small particles were buried and formed aggregates. There was a highly cemented phases produced between soil particle matrix. XRD analysis also confirmed the presence of CaCO3 crystal after the MICP process.

A Two-Step Screening Algorithm to Solve Linear Error Equations for Blind Identification of Block Codes Based on Binary Galois Field

( Qian Liu ),( Hao Zhang ),( Peidong Yu ),( Gang Wang ),( Zhaoyang Qiu ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.9

Existing methods for blind identification of linear block codes without a candidate set are mainly built on the Gauss elimination process. However, the fault tolerance will fall short when the intercepted bit error rate (BER) is too high. To address this issue, we apply the reverse algebra approach and propose a novel “two-step-screening” algorithm by solving the linear error equations on the binary Galois field, or GF(2). In the first step, a recursive matrix partition is implemented to solve the system linear error equations where the coefficient matrix is constructed by the full codewords which come from the intercepted noisy bitstream. This process is repeated to derive all those possible parity-checks. In the second step, a check matrix constructed by the intercepted codewords is applied to find the correct parity-checks out of all possible parity-checks solutions. This novel “two-step-screening” algorithm can be used in different codes like Hamming codes, BCH codes, LDPC codes, and quasi-cyclic LDPC codes. The simulation results have shown that it can highly improve the fault tolerance ability compared to the existing Gauss elimination process-based algorithms.

Anatomic Variants on Computed Tomography in Congenital Aural Atresia and Stenosis

Feng-hua Qin,Tian-yu Zhang,Peidong Dai,Lin Yang 대한이비인후과학회 2015 Clinical and Experimental Otorhinolaryngology Vol.8 No.4

Objectives. To quantitatively analyzing the anatomic variants on temporal computed tomography (CT) in congenital external auditory canal stenosis (EACS), congenital aural atresia (CAA), and normal ear structure. Methods. Through a retrospective study, we analyzed 142 temporal high-resolution CT studies performed in 71 microtia patients. The following 6 parameters were compared among the three groups: Marx classification, medial canal diameter, vertical facial nerve (VFN) anterior displacement, tegmen mastoideum position, tympanic cavity volume, and malleus-incus joint or malleus-incus complex (MIC) area. Results. The results showed that the microtia distributions in the Marx classification in these three groups were significantly different, as 86% (31 of 35) of ears with major microtia (third-degree dysplasia) had an atresia, and in 54.8% (23 of 42) of the minor microtic (first-degree or second-degree) ears, the bony or cartilaginous part of the external auditory canal was stenotic. Measurement data also showed that the potential medial canal diameter of the atresia group was obviously shorter than that of the stenosis group. The VFN anterior displacement and temporomandibular joint backward-shift together lead to medial canal diameters in ears with atresic canals that is smaller than those with stenotic canals. The tegmen mastoideum position was not significantly different between the three groups. Conclusion. The mal-development of the external auditory canal is significantly associated with auricle and middle ear developmental anomalies. Compared with CAA ears, EACS have better development of the auricle, canal, tympanic cavity and MIC and relatively safer surgical operation except for the position of the tegmen mastoideum and the VFN.

Zostera marina Seed Burial can be Enhanced by Manila Clam Ruditapes philippinarum: A Microcosm Study

Chang-Jun Li,Wen Tao Li,Jianying Liu,Xiu-mei Zhang,Peidong Zhang 한국해양과학기술원 2017 Ocean science journal Vol.52 No.2

Seagrass seed bank plays a key role in the regeneration of new vegetation when seagrasses are removed by the natural or man-made disaster. Various factors may affect the development of sediment seed bank. We conducted a microcosm experiment to test the effects of burrowing and feeding activities of Manila clam, Ruditapes philippinarum on the burial of Zostera marina seeds in sediments. The effects of lasting time (3-hour, 1-day, 3-day, 7-day, 14-day and 28-day), clam density (0, 2, 4 and 8 clams with shell length of 3 cm in each microcosm) and clam size (shell length of 2, 3 and 4 cm at 4-clam density) on seed burial were examined in plastic microcosm cores (30 cm high × 10 in inner diameter) in a 28-day period. Results showed that the seed burial depth significantly increased with time, the density and the size of clams. No seeds were buried in the sediment in the cores without clams during the whole experiment period. For the 3-cm clams, about 91.61% of the seeds were buried in the sediment at the end of the experiment in the high-density treatment (8 clams at each core); while in the medium and low-density treatments (4 and 2 clams in each core, respectively), about 76.93% and 60.61% of the seeds were buried in the sediment, respectively. For the size treatments, large (4 cm) clams buried 89.56% of the seeds at the end of the experiment, much more than those of medium (3 cm, 76.93%) and small (2 cm, 61.50%) size clams. During the whole experiment period, nearly all of the buried seeds were at a depth of from 0 cm to 5 cm. These results suggested that Manila clam Ruditapes philippinarum may play an important positive role in seagrass seed bank dynamics in the field.

Study of Deformation Mechanisms of a High-Purity α-Titanium Plate Under Monotonic Loading with the EVPSC-TDT Model

Chao Ma,Xing Duan,Xiaoqian Guo,Hua Qiao,Lianying Zhang,Xianbiao Mao,Peidong Wu 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.2

The deformation mechanisms of a rolled high-purity α-titanium plate under monotonic loading along the rolling direction(RD), transverse direction (TD), and normal direction (ND) are investigated by the Elastic Visco-Plastic Self-Consistent(EVPSC) model, which incorporates a Twinning and De-Twinning (TDT) scheme to describe twinning behavior duringstraining. In the EVPSC-TDT model, plastic deformation is assumed to be accommodated by prismatic, basal and pyramidal⟨c + a⟩ slip modes as well as the 10̄12 extension and 11̄22 contraction twin modes. Numerical results based on theEVPSC-TDT model are in good agreement with the corresponding experimental data. The tension–compression asymmetry,anisotropic initial yielding and strain hardening behavior are interpreted in terms of the predicted relative activities of variousdeformation modes, twin volume fractions and texture evolutions. It is demonstrated that twinning plays an important rolein tension–compression asymmetry and plastic anisotropy, which is closely related to the loading direction with respect tocrystal orientations in the initial texture. In addition, it can be concluded that the TDT scheme permits better performancein describing twinning-associated deformation behavior for the rolled high-purity α-titanium plate than the PredominantTwin Reorientation (PTR) model even when detwinning is not involved.

Enhancing the adsorption function of F⁻ by iron and zirconium doped zeolite: Characterization and parameter optimization

Bo Yang,Chaomin Jia,Guirong Sun,Bingxu Quan,Chunhui Zhang,Qianqian Huo,Peidong Su 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.2

This study presented an original study on the F⁻ removal by Fe and Zr doped Gismondine-dominated Zeolite. Various modified zeolites are prepared by systematically adjusting the synthesis variables, namely pH, mass ratio of zeolite to modify agent (m<SUB>Zeolite:m(Fe+Zr)</SUB>), mass ratio of Fe to Zr (Fe:Zr) to investigate their effects on the F⁻ adsorption. The performance of prepared Fe-Zr-Zeolite on F⁻ removal was examined through both statistic adsorption and dynamic adsorption. Results indicated that when the modified pH was 7, the Fe:Zr ratio was 1:1 and m<SUB>Zeolite:m(Fe+Zr)</SUB> was 1:2, the modified natural zeolites which was named Fe-Zr-Zeolite showed the best removal efficiency on F⁻. Fe-Zr-Zeolite could remove over 80% when the initial concentration was less than 20 mg/L and F⁻ adsorption followed pseudo-second-order adsorption kinetic and Langmuir adsorption isotherm, indicating that F⁻ adsorption by Fe-Zr-Zeolite was chemically dominated. Besides, Fe-Zr-Zeolite had better removal efficiency of F⁻ under acidic conditions than that under alkaline conditions, and the competing anions, typically, Cl-, NO₃⁻ and SO₄<SUP>2-</SUP> had negligible effect on F⁻ removal by Fe-Zr-Zeolite. The dynamic adsorption test demonstrated that in order to maintain the high removal efficiency of F⁻, the filling thickness of Fe-Zr-Zeolite should be at least 30 ㎝ and the small the flow rate is, the higher the F⁻ removal efficiency will be.

The Age-Related Orientational Changes of Human Semicircular Canals

Hui-Ying Lyu,Ke-Guang Chen,Dong-Ming Yin,Juan Hong,Lin Yang,Tian-yu Zhang,Peidong Dai 대한이비인후과학회 2016 Clinical and Experimental Otorhinolaryngology Vol.9 No.2

Objectives. Some changes are found in the labyrinth anatomy during postnatal development. Although the spatial orientation of semicircular canals was thought to be stable after birth, we investigated the age-related orientational changes of human semicircular canals during development. Methods. We retrospectively studied the computed tomography (CT) images of both ears of 76 subjects ranged from 1 to 70 years old. They were divided into 4 groups: group A (1–6 years), group B (7–12 years), group C (13–18 years), and group D (>18 years). The anatomical landmarks of the inner ear structures were determined from CT images. Their coordinates were imported into MATLAB software for calculating the semicircular canals orientation, angles between semicircular canal planes and the jugular bulb (JB) position. Differences between age groups were analyzed using multivariate statistics. Relationships between variables were analyzed using Pearson analysis. Results. The angle between the anterior semicircular canal plane and the coronal plane, and the angle between the horizontal semicircular canal plane and the coronal plane were smaller in group D than those in group A (P<0.05). The JB position, especially the anteroposterior position of right JB, correlated to the semicircular canals orientation (P<0.05). However, no statistically significant differences in the angles between ipsilateral canal planes among different age groups were found. Conclusion. The semicircular canals had tendencies to tilt anteriorly simultaneously as a whole with age. The JB position correlated to the spatial arrangement of semicircular canals, especially the right JB. Our calculation method helps detect developmental and pathological changes in vestibular anatomy.