Mechanical and Microscopic Properties of Copper-contaminated Soil Solidified with Calcium Carbide Residue, Metakaolin, and Desulfurization Gypsum under Freeze-thaw Cycles

Qiang Wang,Dandan Ge,Guojun Cai,Man Li,Liuyan Wu,Huangrui Xu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

The solidification/stabilization effect of heavy metal contaminated soils in frozen soil regions may be weakened. A novel binder comprising calcium carbide residue, metakaolin, and desulfurization gypsum was used to solidify and stabilize copper-contaminated soil subjected to freeze-thaw (F-T) cycles. The unconfined compressive strength (UCS), F-T cycles, scanning electron microscope (SEM), X-ray diffraction (XRD), and pH tests were conducted to investigate the characteristics of UCS, deformation, pH value, and microscopic mechanism of contaminated soils. The results demonstrated that the UCS of contaminated soils decreased with the increasing F-T cycles and Cu2+ concentration; the strength loss rate increased first and then decreased as the F-T cycles increased. The failure strain rose first and then reduced with the increase of F-T cycles, and increased with the rise of Cu2+ concentration. There was a considerable correlation between UCS, failure strain, and deformation modulus E50. The pH value decreased with the increasing F-T cycles and Cu2+ concentration. The microscopic characteristics indicated that the formation of hydrated calcium silicate and ettringite was the fundamental reason for the enhanced UCS. Besides, heavy metals could be solidified and stabilized by chemical precipitation, physical encapsulation, and ion exchange. The effect of F-T cycles could significantly damage the internal structure of contaminated soils, and the frost heaving force could loosen the soil skeleton structure, leading to the deterioration of the mechanical properties.

A structure-based approach to evaluation product adaptability in adaptable design

Qiang Cheng,Guojun Zhang,Zhifeng Liu,Peihua Gu,Ligang Cai 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.5

Adaptable design, as a new design paradigm, involves creating designs and products that can be easily changed to satisfy different requirements. In this paper, two types of product adaptability are proposed as essential adaptability and behavioral adaptability, and through measuring which respectively a model for product adaptability evaluation is developed. The essential adaptability evaluation proceeds with analyzing the independencies of function requirements and function modules firstly based on axiomatic design, and measuring the adaptability of interfaces secondly with three indices. The behavioral adaptability reflected by the performance of adaptable requirements after adaptation is measured based on Kano model. At last, the effectiveness of the proposed method is demonstrated by an illustrative example of the motherboard of a personal computer. The results show that the method can evaluate and reveal the adaptability of a product in essence, and is of directive significance to improving design and innovative design.

DC Voltage Balancing and Current Sharing Control of Parallel Multiple Modules Static Var Generator Based on CPS-SPWM

Cai, Wei,Huang, Yanyan,Fangyuan, Zhou,Qiu, Wenjun,Wang, Caixiao,Wu, Qiang,Erlei, Shi,Wen, Tao The Korean Institute of Electrical Engineers 2013 The Journal of International Council on Electrical Vol.3 No.1

For extending the power and improving the performance of SVG, a topology with several parallel plugging convertor modules is obtained, which has no common DC bus. In respect that the parameter difference among converters, reactive power of total output sharing has to be resolved. In this article, mathematics model with DQ analytic transformation is analyzed. Based on double close-loop decoupling control, and direct current control, a reactive power balance current sharing method is proposed. By using CPS-SPWM, the current harmonic of SVG is reduced, which is indicated by simulation result. Further, in order to apply the method to project application, a 2Mvar platform with a double FPGA-DSP controller broad is carried out. The simulation and practical performance of SVG are given. The validity and feasibility of the method is demonstrated by the results.

Analysis of hysteresis rule of energy-saving block and invisible multi-ribbed frame composite wall

Qiang Lin,Sheng-Cai Li,Yongfu Zhu 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.2

The energy-saving block and invisible multi-ribbed frame composite wall (EBIMFCW) is a new type of load-bearing wall. The study of this paper focus on it is hysteresis rule under horizontal cyclic loading. Firstly, based on the experimental data of the twelve specimens under horizontal cyclic loading, the influence of two important parameters of axial compression ratio and shear-span ratio on the restoring force model was analyzed. Secondly, a tetra-linear restoring force model considering four feature points and the degradation law of unloading stiffness was established by combining theoretical analysis and regression analysis of experimental data, and the theoretical formula of the peak load of the EBIMFCW was derived. Finally, the hysteretic path of the restoring force model was determined by analyzing the hysteresis characteristics of the typical hysteresis loop. The results show that the curves calculated by the tetra-linear restoring force model in this paper agree well with the experimental curves, especially the calculated values of the peak load of the wall are very close to the experimental values, which can provide a reference for the elastic-plastic analysis of the EBIMFCW.

Ankrd7, a Novel Gene Specifically Expressed in Sertoli Cells and Its Potential Roles in Sertoli Cell Maturation

Yu-Qiang Shi,Lian-Cai Du,Qing-Zhong Wang,Chun-Fang Han 한국분자세포생물학회 2009 Molecules and cells Vol.27 No.2

The somatic Sertoli cells play an essential role in testis determination and spermatogenesis by providing nutrition and structural support. In the current study, we report on the novel Ankrd7 gene that contains five ankyrin repeat domains. This gene was specifically expressed in Sertoli cells and was regulated in a maturation-dependent manner. Its expression was restricted to testicular tissue, and its mRNA could be detected in testes at as early as 14 dpp (days post partum) using RT-PCR analysis. In both testicular tissue sections and in vitro cultured Sertoli cells, the Ankrd7 protein was localized to the nucleus of the Sertoli cell. Immunohistochemistry and immunocytochemistry investigations showed that the protein was detectable in testicular tissues at 20 dpp, at which time Sertoli cells were gradually differentiating into their mature cellular form. These results suggest that Ankrd7 is probably involved in the process of Sertoli cell maturation and in spermatogenesis.

Synthesis, Characterization and pH-Responsive Self-Assembly Behavior of Amphiphilic Multiarm Star Triblock Copolymers Based on PCL, PDEAEMA, and PEG

You Qiang Yang,Wen Jing Lin,Li Juan Zhang,Cheng Zhi Cai,Wei Jiang,Xin Dong Guo,Yu Qian 한국고분자학회 2013 Macromolecular Research Vol.21 No.9

A series of amphiphilic 4- and 6-armed star triblock copolymers based on poly(ε-caprolactone) (PCL),poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA), and poly(poly(ethylene glycol) methyl ether methacrylate)(PPEGMA) were designed and synthesized by a combination of ring opening polymerization (ROP) and continuous activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). The continuous ARGET ATRP of DEAEMA and PEGMA was in situ monitored by react infrared spectroscopy (ReactIR) and showed good first-order kinetic characteristics. The molecular weights and chemical structures of the copolymers and their precursors were confirmed by gel permeation chromatography (GPC) and 1H NMR. The critical micelle concentration (CMC) values of the star copolymers in aqueous solution were extremely low (2.2-4.0 mg/L), depending on the architecture of the copolymers. The pH-responsive self-assembly behavior of the star copolymers in aqueous solution was investigated by a combination of dynamic light scattering (DLS), UV-vis spectrometry and scanning electron microscopy (SEM). When the pH values decreased from 10 to 3, no obvious fluctuation of the visible light transmittance of the micelle solutions was observed for lower polymer concentrations of 0.1 and 1 mg/mL, while sharp increase occurred at higher concentration of 10 mg/mL. The hydrodynamic diameters (Dh) of the micelle solutions appeared slight increase with the increase of concentration, and increased rapidly as the pH decreased from 10 to 4 followed by a slight decrease at pH 3. The effects of pH value on the zeta potentials exhibited almost the same tendency with the Dh. This may due to the fact that the protonation of tertiary amine groups in DEAEMA can induce the swelling of micelles. The PCL and PDEAEMA contents and the topological structures (4-or 6-arm) showed significant influences on the pH-sensitivity of the micelles. Overall, the results demonstrated that the structures and pH-sensitivity of these amphiphilic copolymers could be well-controlled and their self-assembled micelles are promising carriers for delivery of anticancer hydrophobic drugs.

Effect of Ion Source Current on the Microstructure and Properties of Cr-DLC Coatings Prepared by Ion Beam-Assisted Arc Ion Plating

Yao Cai,Huidong Liu,Ye Ma,Qiang Wan,Hao Cheng,Yan Liu,Yanming Chen,Qingsong Mei,Bing Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5

Cr-containing diamond-like carbon (Cr-DLC) nanocomposite coatings were synthesized by ion beam-assisted arc ion plating with varying hollow cathode ion source (HCIS) currents. The morphologies, compositions and microstructures were characterized by scanning electronic microscopy (SEM), atomic force microscopy (AFM), X-Ray photoelectron spectrometer (XPS), Raman spectroscopy, grazing incidence X-ray diffraction (GIXRD) and high-resolution transmission electron microscopy (HRTEM). Hardness and friction coefficient were investigated by using nanoindentation and ball-on-disc tribometer, respectively. With no HCIS current, the coating exhibits the maximal growth rate and a rough surface, as well as lower hardness and elastic modulus. With the increasing HCIS current from 40 A to 80 A, the growth rate and the content of chromium carbide decrease obviously, the sp3/sp2 ratio increases initially to the maximum at the HCIS current of 60 A, the highest hardness and elastic modulus are obtained at the HCIS current of 50 A. It is also revealed that moderate HCIS current can reduce surface roughness obviously and promote tribological properties. The correlation of the HCIS current with the microstructure and performance of Cr-DLC coating has been established.

Residual Surface Topology Modeling and Simulation Analysis for Micro-Machined Nozzle

Yukui Cai,Zhan-qiang Liu,Zhen-yu Shi,Qinghua Song,Yi Wang 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

The performance of the micro nozzle is determined primarily by its machined surface topology. A circular cross-section micro-Lavalnozzle is modeled and studied by using numerical simulation in this paper. The geometry of residual height and residual area ofmachined nozzle surface with flat-end milling cutter and ball-end milling cutter are created. It is found that the ball end milling cutterwith large diameter is better than the flat one for nozzle finishing operations. The nozzle velocity performance is also revealed in thisresearch. When residual height increased from 0.6 μm to 9.6 μm for nozzle with throat diameter less than 2 mm, the maximum outletvelocity of nozzle reduced gradually. The maximum outlet velocity of nozzle remains stable for the nozzle with throat diameter greaterthan 2 mm. The results show that the maximum outlet velocity of nozzle significantly reduces with throat diameter decreasing underconstant residual height. Based on the analysis about velocity boundary layer, when residual height changing from 0.6 μm to 9.6 μm,the nozzle with throat diameter is 1 mm, has the boundary layer thickness ranging from 5% to 14% of outlet radius.

Numerical simulation on the typhoon-induced dynamic behavior of transmission tower-line system

Yunzhu Cai,Jiawei Wan,Qiang Xie,Songtao Xue 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.4

The spatiotemporal impact of typhoons moving across transmission networks is increasingly evident, which may result in the failure of the overhead transmission tower-line (TL) system. The structural design and safety assessment to transmission TL systems that subjected to extreme winds are necessary. This paper aims to provide fundamental insights on the wind field caused by typhoons as well as the typhoon-induced dynamic loads and responses of the transmission TL system, by means of the numerical simulation. This paper offers a numerical scheme to simulate the typhoon-induced wind field on a TL system, in which the movement of the typhoon center and the nonstationary fluctuation of the wind are concerned. In the scheme, the near-surface mean wind speed is calculated based on the radial profile and translation of storms; the nonstationary fluctuation component is generated by a time-varying modulation function. By applying the simulated wind field to the finite element model of TL system, we yield the dynamic responses of the TL system as well as the dynamic loads resulting from the interaction between the structure and wind. Utilizing the evolutionary power spectral density (EPSD) function, the fluctuating wind loads and structural responses are addressed both in the time and frequency domains. Further discussion is done on the typhoon-induced loads by constructing the dynamic equivalent factors. The time-varying equivalent factors show the stationary process, which demonstrates the fading out of the non-stationarity for simulated wind loads. The comparison result indicates that the gust response factor of tower recommended by design codes may not be safe enough when the typhoon impact is concerned.

Surgical Outcomes of Symptomatic Intramedullary Spinal Cord Cavernous Malformations: Analysis of Consecutive Cases in a Single Center

Zheng Cai,Xinjie Hong,Wei Dai,Zhengwei Zhang,Qiang Liang,Xuehua Ding,Wei Sun 대한척추신경외과학회 2023 Neurospine Vol.20 No.3

Objective: Intramedullary spinal cavernous malformations (ISCMs) are rare vascular lesions of the spinal cord with unclear natural history and controversy over treatment. This study aimed to report a series of symptomatic ISCMs underwent microsurgical management to illustrate the natural history, clinical presentation, and surgical outcomes and to evaluate factors associated with hemorrhage events and neurological prognosis. Methods: This single-center retrospective study included 29 consecutive patients with whose demographic, symptomology, imaging, neurological, and surgical data were collected. The risk for hemorrhage events and factors affecting surgical outcomes were retrospectively analyzed. Results: There were 12 female (41.4%) and 17 male patients (58.6%), with an average age of 45.2 years (range, 17–69 years). The mean size of the lesion was 9.7 mm (range, 3–20 mm). Most patients had a bowel or/and bladder dysfunction symptom (n = 11, 37.9%), followed by sensory deficits (n = 5, 17.2%), gait disturbance (n = 5, 17.2%), pain (n = 4, 13.8%), and weakness (n = 4, 13.8%), most (n = 15, 51.7%) with a chronic onset. All patients received total resection without rehemorrhages after surgical resection in follow-up. Sixty-five point five percent patients (n = 19) improved, 13.8% (n = 4) remained stable, 20.7% (n = 6) got worsen. The overall annual hemorrhage risk was 2.1% per patient-year. A total of 27 hemorrhages occurred in the 18 patients, of which rehemorrhage rate increased to 50.0% (n = 9) with a previous history of hemorrhage. Patients with smaller lesion sizes were more likely to have hemorrhage or rehemorrhage events (p = 0.008). Recurrent hemorrhage of the lesions was a risk factor for neurological outcomes (p = 0.016). Conclusion: The risk of rehemorrhage was significantly increased in symptomatic ISCM patients with a previous history of hemorrhage. Rehemorrhage was a risk factor for neurological outcomes. Patients can benefit from microsurgical treatment to avoid rehemorrhage and further neurological deterioration.