Synoptic characters of dust storm process occurred in Chifeng

WANG Guoqin,YOU Li 한국기상학회 2006 한국기상학회 학술대회 논문집 Vol.2006 No.-

Preparation of Supported CTAB/MCM-41 and CTAB-Nafion/MCM-41 Mesoporous Molecular Sieve and Their Use in the Brominating Reaction

Hu, Guoqin,Li, Hua,Liu, Juan,Zhu, Jiang Korean Chemical Society 2011 대한화학회지 Vol.55 No.4

CTAB 혹은 CTAB-나피온 촉매를 속빈 실리콘 튜브형 MCM-41에 담지시켰다. 이들 촉매들을 XRD, SEM, BET 등으로 분석하였다. 이들을 1,7-heptanediol 의 브롬화 반응 촉매로 사용하였고 다른 촉매들과 비교하였다. 이들 촉매들은 CTAB 보다 효과가 좋았으며 CTAB-Nafion/MCM-41 이 성능이 가장 우수하였다. CTAB or CTAB-Nafion catalyst were successfully supported on siliceous hollow tubular MCM-41 which synthesized by hydrothermal method using CTAB as a single template or CTAB and Nafion-Na as mixed templates. The properties of two kinds of catalysts were characterized with XRD, SEM and adsorption and desorption isotherms of nitrogen and pore diameter distribution, respectively. Then they were applied to catalyze brominating reaction of 1,7-heptanediol, moreover the rate of brominating reaction with different catalysts was compared. The results showed that catalytic activities of CTAB/MCM-41 and CTAB-Nafion/MCM-41 are better than CTAB, and that of CTAB-Nafion/MCM-41 is the best because of its phase-transfer and strong acidity function. The two kinds of catalysts can be separated from the reactive products and recycled.

Study of Thermodynamic Mechanism for Using Organic Solvent to Extract Isoflavone from Soybean Residuals

Hua, Li,Guoqin, Hu,Dan, Li Korean Chemical Society 2009 대한화학회지 Vol.53 No.4

대두 잔기로부터 유기용매를 사용하여 이소플라본을 추출하는 열역학적 메카니즘을 조사하였다. 대두 잔기로부터 유기용매를 사용한 이소플라본 추출과정에서의 분배 계수를 결정하기 위한 간단한 모델을 설정하고 $K,\;{\Delta}H^0,\;{\Delta}S^0\;and\;{\Delta}G^0$ 간에 열역학적 함수를 계산하였다. 그 결과 대두 이소플라본 추출은 흡열과정이며 엔트로피 증가과정임을 발견하였다. 온도가 증가할수록 ${\Delta}G^0$가 감소하였다. The thermodynamical mechanism of the extraction of soybean isoflavones from soybean residuals using organic solvent method has been studied. On the basis of experiments, a simple model for determining the distribution coefficients in organic solvent extraction was employed to calculate the thermodynamical functions between $K,\;{\Delta}H^0,\;{\Delta}S^0\;and\;{\Delta}G^0$ in the soybean isoflavones extraction process. The results show that the soybean isoflavones extraction is an endothermic and an entropy-increasing process: the ${\Delta}G^0$ decreases when the temperature arises.

Grain Refinement and Second Phases Evolution of Mg-13Gd-4Y-2Zn-0.4Zr Sheet During Processing by Rotary Forward Extrusion

Zhaocan Li,Guoqin Wu,Yunfang Liu,Jianmin Yu 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11

The grain refinement and second phases evolution of Mg-13Gd-4Y-2Zn-0.4Zr sheet during the rotary forward extrusion(RFE) process were investigated. The microstructures were observed by using optical microscopy, scanning electron microscopy,electron backscatter diffraction, X-ray diffractometer, and transmission electron microscope. The result shows, the modifiedcellular automata model fully considers the influence of long-period stacking ordered phase on the dislocation density,which can predict the grain size evolution of Mg-Gd-Y-Zn-Zr alloy during the RFE process, and the relative error can becontrolled within 10%. With the increase of RFE revolutions, the average grain size firstly decreases quickly (RFE1–RFE25),and then increased gradually (RFE25–RFE100). The decreased grain size is related to the enhanced dynamic recrystallizationprocess as the c-axis of most grains is rotated continuously to a transverse direction and more random texture types areformed. The increase in grain size is linked with the solid solution of the second phase, and the limitation on grain growthdue to the pinning effect of the second phase almost disappears. In the early stage (RFE1–RFE25), the contribution percentageof grain refinement and solid solution strengthening to microhardness improvement is 180.6% and 61.7%, respectively. In the subsequent stage (RFE25–RFE100), the dislocation density strengthening and solid solution strengthening accountsfor 60% and 440% of the increase in microhardness, respectively.

Robust Control for Uncertain Hybrid Robot with Fluid Resistance Using Unmeasured Auxiliary Variables-based Time-varying Gain Extended State Observer

Qiuyue Qin,Guoqin Gao,Junwen Zhong,Mengyang Ye 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.11

For the trajectory tracking control of uncertain hybrid robot with fluid resistance, the matched and mismatched uncertain problem is a challenge. The matched uncertainties include joint friction, modeling error and so on. And the fluid resistance may cause the time-varying discontinuous mismatched uncertainty. Thus, the unmeasured auxiliary variables-based second-order sliding mode control with time-varying gain extended state observer for the hybrid robot is proposed. By defining unmeasured auxiliary state variables, the dynamic equation of hybrid robot with mismatched uncertainty of fluid resistance is reconstructed into a state equation with only matched uncertainty structure. To observe and compensate the lumped uncertainty including matched uncertainties, fluid resistance uncertainty and unmeasured auxiliary state variables of hybrid robot, an extended state observer is designed, which only needs the condition of bounded uncertainty change rate. Moreover, by devising the continuous adjustment rule for observer gain’s transient process, the observed error converges quickly and the initial peaking value of system state observation is reduced. To suppress the residual error of uncertainty compensation, the unmeasured auxiliary variables-based super-twisting sliding mode control algorithm is combined with the time-varying gain extended state observer, which could enhance system robustness and weaken chattering of the sliding mode control. The stability of the closed-loop system is proved by Lyapunov stability theorem. Finally, taking the hybrid robot for automobile electro-coating conveying as an example, simulations and experiments are conducted on the prototype system to demonstrate the effectiveness of the proposed control method.

Finite-time Stable Robust Sliding Mode Dynamic Control for Parallel Robots

Mengyang Ye,Guoqin Gao,Junwen Zhong 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.9

To address the tracking control problem for n-DOF parallel robots in presence of the lumped disturbance, including modeling errors, friction and external disturbance, a finite-time stable robust sliding mode dynamic control (FRSMDC) for parallel robots is explored. From the implementation condition of the FRSMDC for parallel robots, the limitation on the change rate of the lumped disturbance is relaxed for easy realization. From the results of the FRSMDC for parallel robots, the finite-time stability of the sliding variable is proved and the settling time is derived; the switching gain required is only larger than the upper bound of the disturbance estimation error, instead of the upper bound of the disturbance, due to the feed-forward compensation to the lumped disturbance via a disturbance observer. Consequently, the system robustness is improved and the chattering of FRSMDC is alleviated. The finite-time stability of the closed-loop system is confirmed with Lyapunov theory. Besides, the application of the proposed method is extended to a general multi-input multi-output nonlinear system with the relative degree m by analogy. Finally, the case of the dynamic control of a 6-DOF parallel robot for automobile electro-coating conveying is studied for simulation and experiment, so as to attest the validity of the FRSMDC for parallel robots.

Application of the Microwave-assisted Process to the Fast Extraction of Isoflavone from the Waste Residue of the Soybeans

Hua, Li,Guoqin, Hu,Dan, Li Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

Due to the importance of isoflavone content in soybean extracts, the microwave-assisted process (MAP) was compared to the conventional extraction methods. For comparison of the three methods, all extraction parameters (solvent, sample to solvent ratio, temperature, etc.) were kept the same; the microwave extractor was operated at 187.5 W with an emission frequency of 2450 MHz under atmospheric pressure conditions and the extractions were carried out at 75 ${^{\circ}C}$ for 3 min while the conventional reflux was at 75 ${^{\circ}C}$ for 3 h. Total yield and crude isoflavone content were determined by ultraviolet spectrophotometric and compared with the three methods. Results indicated that the MAP was comparable to the conventional method in its capability to extract target compounds without causing any degradation; in addition it dramatically reduced the extraction time from 3 h to a few minutes, suggesting that it can be an alternative technique to the time-consuming conventional reflux method.

Spinal Angiolipomas : Clinical Characteristics, Surgical Strategies and Prognosis

Xiaolei Zhang,Sheng Dong,Guoqin Wang,Huifang Zhang,James Jin Wang,Guihuai Wang 대한신경외과학회 2022 Journal of Korean neurosurgical society Vol.65 No.1

Objective : Angiolipomas are usually found in the subcutaneous tissue of the trunk and limbs. Spinal angiolipomas (SALs) are uncommon and have rarely been reported. We report a series of nine SALs patients who received surgical treatment in our department. To summarize the clinical characteristics of SALs, propose our surgical strategies, and evaluate the effects of the operation. Methods : This was a retrospective review of nine SALs patients who received surgical treatment from August 2015 to March 2020. Total or subtotal resection was determined by the axial localization (dorsal or ventral) and the extent of intervertebral foramen involvement. The outcomes were assessed based on the modified Japanese Orthopaedic Association (mJOA) scoring system utilized before surgery and at various follow-up points. Results : Among the nine patients, the mean mJOA score before surgery was 6.6±2.3, compared with 10.1±1.1 at the last follow-up time point (33.4±11.8 months). All patients achieved good outcomes, even in cases of subtotal resection. Conclusion : Early surgical resection of SALs is recommended, and the specific procedures should be determined by the axial localization (dorsal or ventral) and the extent of intervertebral foramen involvement. Most of the patients had a good prognosis, even in cases of subtotal resection.

Electrochemical Investigation of Tryptophan at a Poly(p-aminobenzene sulfonic acid) Film Modified Glassy Carbon Electrode

Yu Ya,Dengbai Luo,Guoqin Zhan,Chunya Li* 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.5

A glassy carbon electrode (GCE) modified with poly(p-aminobenzene sulfonic acid) [Poly(p-ABSA)] film is fabricated by voltammetric technique in phosphate buffer solution (pH 8.0) containing 5.010-3molL-¹ p-ABSA. Electrochemical behaviors of tryptophan at the Poly(p-ABSA) film electrode are investigated with voltammetry. The results indicate that the electrochemical response of tryptophan is improved significantly in the presence of poly(p-ABSA) film. Compared with the bare glassy carbon electrode, the Poly(p-ABSA) film electrode remarkably enhances the irreversible oxidation peak current of tryptophan. Some parameters such as voltammetric sweeping segments for the electrochemical polymerization, pH, accumulation potential and accumulation time are optimized. Under the optimal conditions, the oxidation peak current is proportional to tryptophan concentration in the range of 1.0 10-7 to 1.0 10-6 mol L-¹, and 2.0 10-6 to 1.0 10-5 mol L-¹ with a detection limit of 7.0 10-8 mol L-¹. The proposed procedure is successfully applied to the determination of tryptophan in a commercial amino acid oral solution.

Application of the Microwave-assisted Process to the Fast Extraction of Isoflavone from the Waste Residue of the Soybeans

Li Hua,Hu Guoqin,Li Dan 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

Due to the importance of isoflavone content in soybean extracts, the microwave-assisted process (MAP) was compared to the conventional extraction methods. For comparison of the three methods, all extraction parameters (solvent, sample to solvent ratio, temperature, etc.) were kept the same; the microwave extractor was operated at 187.5 W with an emission frequency of 2450 MHz under atmospheric pressure conditions and the extractions were carried out at 75 oC for 3 min while the conventional reflux was at 75 °C for 3 h. Total yield and crude isoflavone content were determined by ultraviolet spectrophotometric and compared with the three methods. Results indicated that the MAP was comparable to the conventional method in its capability to extract target compounds without causing any degradation; in addition it dramatically reduced the extraction time from 3 h to a few minutes, suggesting that it can be an alternative technique to the time-consuming conventional reflux method.