Chaotic behavior of in-line bubbles rising with coalescences in non-Newtonian fluids: A multiscale analysis

Shaokun Jiang,Youguang Ma,Wenyuan Fan,Ke Yang,Huaizhi Li 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.1

The nonlinear dynamics of in-line bubbles rising with coalescence in non-Newtonian Carboxymethylcellulose sodium (CMC) fluids was studied through the techniques such as the multiresolution signal decomposition and the chaotic time series analysis. The temporary signals of bubble passages collected by an optical sensing device at different heights were investigated by a 12-level wavelet decomposition and the scalewise characteristics of bubble motion were extracted and analyzed. The chaotic time series analysis distinguished the periodicity or the deterministic chaos of bubble motion successsfully. The calculation of Kolmogorov entropy proves that in the ranges of experimental heights and gas flowrates, the bubble rising dynamics becomes more chaotic with the increase of height, and reaches the maximum chaotic extent in a certain height, while with the further increase of height, the chaotic extent decreases slowly. With the increase of gas flowrate, at the lower height, the bubble rising dynamics changes from periodicity to deterministic chaos, and at the higher heights it reaches the maximum chaotic extent in a certain gas flowrate; however,for both cases, it has little change in the higher gas flowrates. Moreover, with the increase of CMC concentration, the bubble rising dynamics becomes less chaotic when the height is beyond a certain value.

Settlement and Load Transfer Mechanism of Pipeline Due to Twin Stacked Tunneling with Different Construction Sequences

Shaokun Ma,Ying Liu,Xilin Lv,Yu Shao,Ye Feng 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10

The tunnel-pipeline-soil interaction is attracting more and more wide range of scholars and was treated as a plane strain problem, with little attention given to the responses of existing pipeline to twin-tunneling process with different construction sequences. Moreover, there are rare reports available on the influences of tunnel construction sequences on an existing pipeline. In this study, a three-dimensional centrifuge model test and numerical simulations using an advanced hypoplasticity constitutive model were conducted to investigate the influences of twin stacked tunneling with different construction sequences on an existing pipeline. The results shows that the maximum values of greenfield ground settlement, pipeline settlement and additional pipeline bending strain due to twin stacked tunneling when the upper tunnel was excavated first were 25%, 18% and 11% larger, respectively, than those when the lower tunnel was excavated first. The maximum values of greenfield ground settlement, pipeline settlement and additional pipeline bending strain due to twin stacked tunneling when the lower tunnel was excavated first were slightly smaller than those when the twin tunnels were excavated simultaneously. After the twin-tunneling process, the sagging regions were located within ± 1.5DT (tunnel diameter) in these three conditions. The maximum pipeline bending strain within the hogging regions was approximately half of that within the sagging regions. Because of shielding effects from the upper tunnel, the region where vertical stress of the soil reduced was transferred to both sides of the tunnel due to the second tunneling process when the upper tunnel was excavated first. As a result, the extended sagging regions due to the second tunneling process when the upper tunnel was excavated first were two times than that when the lower tunnel was excavated first.

Synthesis of bi-functionalized ionic liquid - mesoporous alumina composite material and its CO2 capture capacity

Liwei Sun,Shaokun Tang 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.10

Bi-functionalized ionic liquid (IL) - mesoporous alumina (MA) composite material was synthesized and used for CO2 capture. Ordered mesoporous alumina was synthesized by self-assembly method with aluminum isopropoxide as aluminum source. Then bi-functionalized ionic liquid 1-methoxyethyl-3-methyl imidazole glycinate ([MOEmim][Gly]) was immobilized on mesoporous alumina by ultrasonic-assisted impregnation method. Ordered mesostructure of alumina keeps well in the composite material. Compared with bi-functionalized ionic liquid, thermal stability of the composite material greatly improved. Finally, CO2 capture capacity of IL-MA composite material was studied under different temperatures. On the basis of both capture capacity and capture rate, 40 oC is the optimal temperature. The capture capacity is 1.42mol·mol IL−1 - equivalent to 144mg·g sorbent−1, which is higher than IL or MA alone. Furthermore, the capture capacity of composite material almost maintains constant after eight capture-regeneration cycles.

Microfluidic step emulsification techniques based on spontaneous transformation mechanism: A review

Ziwei Liu,Cong Duan,Shaokun Jiang,Chunying Zhu,Youguang Ma,Taotao Fu 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-

Rapid and robust generation of uniformly sized droplets is a research hotspot for emulsificationtechnology. Compared with conventional microfluidic devices such as cross-junction andflow-focusing,the size of the droplets generated in the step emulsifiers based on the spontaneous transformationmechanism is independent of theflowfluctuation, making this type of devices have many advantagesand important application value. To introduce the research progress of step emulsification technology inrecent years, this review discusses the device configurations, interfacial evolution for droplet formationmechanism,flow pattern classification, the influence of control variables on the emulsification processand the application advantages of such devices, and illustrates the design and selection principles of suchdevices, the control laws of manipulation variables, and the future applicationfields and directions.

Comparison of formation of bubbles and droplets in step-emulsification microfluidic devices

Wei Zhang,Ziwei Liu,Shaokun Jiang,Chunying Zhu,Youguang Ma,Taotao Fu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.106 No.-

Monodispersed microbubbles and microdroplets are widely used as reaction carriers in microfluidics. Inthis study, the generation processes of bubbles and droplets in a step-emulsification microfluidic deviceare compared to show the similarities and differences in the emulsification process. By changing theplacement of the microdevice, the effects of buoyancy and gravity on the generation of bubbles and dropletsare introduced, and the feedback mechanism of the bubble layer and the effect of droplet accumulationon the emulsification process are clarified. Finally, based on the analysis of the difference of thepinch-off of the dispersed phase between the bubble and the droplet in this configuration, the Plateau-Rayleigh instability processes for the formation of bubble and droplet are revealed by using a highspeedcamera system, and the reasons for the difference of the operating ranges of the gas flow rateand liquid flow rate in the dripping flow regime are explained.

Combination of supercritical fluid elution and resin adsorption for removal of procymidone from ginseng extracts

Guangtao Li,Liwei Sun,Shaokun Tang 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.4

We propose a new method of resin adsorption (RA) coupled with supercritical fluid elution (SFE) for removal of pesticide residue and recovery of ginsenosides from ginseng extracts. D-101-1 resin was selected as the proper adsorption resin, acetone-n-hexane (4 : 6, v : v) served as the modifier with the flow rate of 1.5mL/min during supercritical CO2 elution of procymidone at 25MPa, 55 oC for 2 h, and absolute ethanol as the modifier at a flow rate of 1mL/min for supercritical CO2 elution of ginsenosides at 20MPa, 60 oC and 1 h. The results showed that the content of procymidone in the final products was only 0.0089mg/kg. Meanwhile, the recovery rate of ginsenosides reached up to 92.5%. RA-SFE procedure provides an efficient approach to remove pesticide residue traces with little loss of active ingredients. The used resin can be recycled without any additional regeneration.

Parameter Sensitivity Analysis of a New Fabricated Rectangular Tunnel Joint Using Numerical Method

Zhen Huang,Chenlong Zhang,Shaokun Ma,Hai Zhang,Zhang Zhou,Hongzhou Li 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.2

An assembled rectangular tunnel has the advantages of high space utilization rate and strong urban applicability. This solution has been widely used in urban underground traffic construction. During their construction and operation, the joints are the weakest parts of the structure. The mechanical behavior of joints is closely related to the safety of the tunnel; thus, it is important to use a joint with good mechanical behavior. This study presents a new type of joints for shallow buried assembled rectangular tunnels. To evaluate the effect of design parameters (tenon depth and tenon angle) on the behavior of joints, the finite element method was used. At the same time, the mechanical behavior of rectangular tunnel joint was analyzed and compared with that of a traditional straight joint under the same loading conditions, showing better results. The performance-based engineering (PBE) concept was implemented to evaluate the robustness of rectangular tunnel joints. The results show that if the bolt is placed on the tensile side of the structure, it provides a strong restraining effect on the deformation of the joint. When the tenon depth and angle are 0.8 m and 3.6°, respectively, the overall behavior of the rectangular tunnel joint was improved. The new type of assembled rectangular tunnel joint designed in this study has a good application prospect in a shallow stratum and provides new ideas for the design and construction of such tunnels.

Facile microwave-assisted solvothermal synthesis of rod-like aluminum terephthalate [MIL-53(Al)] for CO2 adsorption

Liwei Sun,Meilin Yin,Zhen Li,Shaokun Tang 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.112 No.-

To alleviate environment issues derived from CO2 emission, developing effective and economical methodsfor CO2 capture has attracted much attention for decades. Metal-organic frameworks possess highporosity and stability, which is favorable to the adsorption of small molecules. Herein, an aluminumbasedMOF, aluminum terephthalate [MIL-53(Al)], was synthesized with H2O and N,N0-dimethylformamide as co-solvent via microwave-assisted method for CO2 adsorption. The parametersincluding pre-mixing mode, microwave temperature, microwave power and reaction time were variedto study their influences on crystal structure, morphology and CO2 adsorption capacity of MW-MIL-53(Al). Wherein, MW-MIL-53(Al) prepared with pre-mixing mode of stirring at 130 C, 200 W and 3 h presentshigh crystallinity and rod-like morphology. The synthesized MW-MIL-53(Al) possesses relativelyhigh BET surface area (961 m2/g), pore volume (0.46 cm3/g) and thermal stability (up to 480 C), andits CO2 adsorption capacity is 2.16 mmol CO2/g adsorbent under 25 C and 0.1 MPa, which is higher thanCS-MIL-53(Al) synthesized via conventional solvothermal method at 130 C for 48 h.

Giant Ganglioneuroma of Thoracic Spine : A Case Report and Review of Literature

Huang, Yong,Liu, Lidi,Li, Qiao,Zhang, Shaokun The Korean Neurosurgical Society 2017 Journal of Korean neurosurgical society Vol.60 No.3

Ganglioneuroma (GN) is a rare benign tumor of neural crest origin usually found in the abdomen, but may occasionally present at uncommon sites including the cervical, lumbar, or sacral spine. However, GNs of thoracic spine are extremely rare. In this report, we describe a 12-year-old girl with giant GN in the thoracic spine, who underwent successful resection (T1-4 level) of the tumor. Histopathological examination confirmed the diagnosis. GN should be considered in the differential diagnosis of any paraspinal mass. A high index of suspicion and correlation of clinico-radiological findings is necessary in differentiating a large benign tumor from a malignant growth. Complete surgical excision is the treatment of choice; however tumor size and location need to be considered for the surgical approach (one-step or multiple surgeries). Close follow-up after surgery is mandatory.

High-performance COF-based composite anion exchange membrane sandwiched by GO layers for alkaline H2/O2 fuel cell application

Jia Chen,Mingming Guan,Kai Li,Shaokun Tang 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-

With well-defined structure and high stability, covalent organic framework (COF) inspires the preparationof new ion-conducting materials for anion exchange membrane (AEM) in alkaline fuel cell. In orderto reveal the influence of micro-nano structure within COF ordered channels on the hydroxide diffusion,we construct a multi-dimensional composite membrane by combining two-dimensional lamellar COFwith one-dimensional polymer chains. The quaternary ammonium-modified COF-LZU1 (QAmCOFLZU1)is incorporated into quaternized poly (2,6-dimethyl-1,4-phenylene oxide) (QAPPO) to fabricateQAmCOF-LZU1/PPO composite membranes. The rapidly diffusion of hydroxide ions in the first solventshell formed by the huge amount of quaternary ammonium groups in the ordered COF channels is investigatedby molecular dynamics simulations. Afterwards, sulfonated graphene oxide (GO) is coated onboth surfaces of the membranes via ionic interactions and p-p interactions to obtain GO@QAmCOFLZU1/PPO sandwich membranes, which would avoid excessive swelling of membranes and leakage ofQA groups. Especially, the GO-sandwiched membrane exhibits strikingly high stabilities and excellentH2/O2 fuel cell performance with a peak power density of 242 mW cm 2 at 60 C. This study providesan effective strategy to construct ion-conducting COF-based composite membranes for highperformancealkaline fuel cell.