Trajectory Optimization for Spacecraft Using a Second-Order Gauss Pseudo Spectral Method

Guoyong Li,Changhou Lu,Wei Pan,Qing Wang 보안공학연구지원센터(IJUNESST) 2015 International Journal of u- and e- Service, Scienc Vol.8 No.1

An optimal control problem for the trajectory of spacecraft under nonlinear constraints is presented. The second-order Gauss pseudo spectral method(GPM) is described for solving the problem numerically. Based on the first-order GPM, the differential matrix of the second-order GPM is derived. The dynamic equations and its constraints are approximated by the two methods. The terminal state constraints of the second-order GPM are converted to two constraints: terminal state variables and the first-order derivative constraints. The first-order GPM and second-order GPM are compared in terms of the accuracy of the state and control, the number of variables in NLP, the convergence time. A key feature of the second-order method is that it provides a more accurate and efficient way than the first-order method, due to reducing the number of variables in the nonlinear programming problem that is transcribed. A numerical example is used to identify the key differences between the two methods. The results of this study indicate that the first-order and second-order Gauss methods are very similar in accuracy, while the computational efficiency of the two methods is significantly different, for the numerical solution of nonlinear optimal control problems.

Spontaneous vesicle formation from trisiloxane-tailed gemini surfactant

Guoyong Wang,Zhiping Du,Dianlong Zhang,Ping Li 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

The spontaneous vesicle formation from a novel trisiloxane-tailed gemini surfactant were reported. The surface tension measurements revealed that aggregates are formed, and dynamic light scattering (DLS) measurements suggested the aggregates are vesicles. The size and morphology were observed by transmission electron microscopy (TEM). The vesicle formation was further confirmed by dye entrapment studies.

Polyglycerol modified polysiloxane surfactants: Their adsorption and aggregation behavior in aqueous solution

Guoyong Wang,Yanyan Zhu,Yunhui Zhai,Wanxu Wang,Zhiping Du,Jieqiong Qin 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.47 No.-

A simple process to synthesize polyglycerol modified polysiloxane surfactants has been carried outapplying a “grafting-to” approach. After formation of allyl polyglycerol ether (APGE) from diglycerol(DGY) and allyl glycidyl ether (AGE), polysiloxane modified by designed number of polyglycerol groups(PHMS-APGE) were obtained by connecting the APGE structure to different Si H functionalizedpolyhydromethyl siloxane (PHMS). The synthesized APGE-PHMS were characterized by IR and 1H NMR. Solubility measurements showed that the solubility of the as-prepared polymers increased in polarsolvents with the increasing of the amount of hydrophilic APGE groups. Furthermore, the surface activity,surface adsorption, aggregation and spreading behaviors of APGE-PHMS were investigated utilizingsurface tension measurements, dynamic light scattering (DLS), transmission electron microscopy (TEM)and contact angle measurements. The results showed that critical aggregation concentration (CAC) andthe time needed to reach adsorption equilibrium on water surface decrease systematically with theincrease in the number of APGE groups. These polymers in aqueous solutions could aggregate to formspherical assemblies. Moreover, the spreading behavior of these polymers on low energy surface wasfound to be influenced by the number of hydrophilic APGE groups.

Surface and foam property of perfluoroalkyl polyoxyethylene ether phosphate salt in aqueous-ethanol system

Bo Ning,Yan Wang,Mi Zhang,Yanyun Bai,Xiumei Tai,Wanxu Wang,Guoyong Wang 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.94 No.-

Foam is used in manyfields with excellent performance. Moreover, disinfectants with ethanol as themain ingredient have increasingly been used in people's lives. However, the foam research of an ethanolwatermixed system is still in the initial stage. In this work, a perfluoroalkyl polyoxyethylene etherphosphate salt surfactant (FEP-Na) was synthesized through a new molecular design. The surfactant hasgood interfacial adsorption behavior in 50% ethanol-water mixing system, and the approximatelyspherical aggregates are observed in the volume phase of the solution. Moreover, FEP-Na showed goodfoaming property in 50% ethanol-water mixed solution. Interestingly, high concentration solutions withhigh surface activity have lower foam stability. And under the microscope, we see that the bubble burst isdominated by the phenomenon of coalescence. In this regard, we explain the mechanism of foamstability by electrostatic double layer theory and interfacial dilation rheology. It provides a new choice forthe synthesis of foaming agent in the ethanol-water mixed system at a concentration of 50%.

Micellization and aggregation properties of sodium perfluoropolyether carboxylate in aqueous solution

Qiwen Yin,Wanxu Wang,Wei Xue,Yanyun Bai,Xiaoyuan Ma,Zhiping Du,Guoyong Wang 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.42 No.-

Sodium perfluoropolyether carboxylate (PFPE-Na) was synthesized via hydrolyzing the correspondinghexafluoropropylene oxide oligomer (PFPF). The structure of PFPE-Na was characterized by FT-IR and 19FNMR. The micellization and aggregation properties of PFPE-Na surfactant in aqueous solution werestudied systematically using equilibrium surface tension, electrical conductivity, dynamic surfacetension, steady-statefluorescence, transmission electron microscopy (TEM) and contact anglemethodologies. The results of equilibrium surface tension at 25 C showed that the critical micelleconcentration (CMC) and the surface tension at CMC (gCMC) of PFPE-Na aqueous solution are lower thansodium perfluorooctanoate [NaPFO, C7F15COONa], which revealing that as a kind of environment-friendly surfactant, PFPE-Na is a perfect substitute of NaPFO. Electrical conductivity measurementsimplied that the micellization of PFPE-Na in aqueous solution was an exothermic and entropy-drivenprocess in the range of temperature investigated. Steady-statefluorescence and transmission electronmicroscopy (TEM) may indicate that PFPE-Na self-assemble in aqueous solution to form larger sphericalaggregates with the increase of concentration. In addition, dynamic surface tension measurements ofPFPE-Na solution showed an extremely efficient adsorption at concentrations above CMC while thedetermination of contact angle of PFPE-Na showed the wetting ability was general.

Adsorption, aggregation and wetting behaviors of biodegradable surfactant: Perfluoropolyether quaternary ammonium salt

Jixian Shen,Yanyun Bai,Qiwen Yin,Wanxu Wang,Xiaoyuan Ma,Guoyong Wang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.56 No.-

A novel cationicfluorinated surfactant, (PFP-AI), was synthesized via amidation and quaterisationsuccessively with perfluorinated acylfluride (PFPF) as starting material. Their structure was analyzed byFT-IR, 1H NMR and 19F NMR. The TG indicated the PFP-AI possess thermal stability with initiationdecomposition temperatures about 217 C. The physicochemical properties of PFP-AI were studiedsystematically by equilibrium surface tension, dynamic surface tension, dynamic light scattingmeasurement (DLS) and transmission electron microscopy (TEM). The results revealed the PFP-AIexhibited high surface activity (gcmc = 16.4 mN/m) and could aggregate into vesicles at the concentrationof 4.15 mmol/L. Furthermore, contact angle measurements demonstrated that PFP-AI exhibited efficientwettability on the hydrophobic surface.

Tissue distribution of marbofloxacin in pigs after a single intramuscular injection

Fan Yang,Yiming Liu,Zhili Li,Yuqin Wang,Baobao Liu,Zhensheng Zhao,Bianhua Zhou,Guoyong Wang 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.2

Tissue distribution of marbofloxacin was studied in pigs after a single intramuscular injection at 2.5 mg/kg body weight. Samples of plasma, muscle, liver, kidney, heart, lung, and muscle at the injection site were randomly collected from five pigs at 2, 6, 10, 24, 48, 72, and 96 h after administration. Marbofloxacin concentrations were determined by using high-performance liquid chromatography with ultraviolet detection and were subjected to non-compartmental analysis to obtain kinetic parameters. The elimination half-life (t1/2lz) of marbofloxacin at the injection site was 22.12 h, while those in kidney, plasma, liver, lung, heart, and muscle were 16.75, 21.48, 21.84, 24.00, 24.45, and 28.91 h, respectively. Areas under the concentration-time curve from 0 h to ∞ (AUC0–∞s) were calculated to be 31.17 hㆍmgㆍmL−1 for plasma and 32.97, 33.92, 34.78, 37.58, 42.02, and 98.80 hㆍmgㆍg−1 for heart, muscle, lung, liver, kidney, and injection site, respectively. The peak concentration (Cmax) of marbofloxacin was 1.62 µg/mL in plasma and 1.71, 1.74, 1.86, 1.93, 2.45, and 7.64 µg/g in heart, lung, muscle, kidney, liver, and injection site, respectively. The results show that marbofloxacin was fast absorbed, extensively distributed, and slowly eliminated from pigs after a single intramuscular administration.

Preparation, characterization, and properties of novel meglumine-based polysiloxane surfactants

Yanyun Bai,Jinxing Li,Xiumei Tai,Guoyong Wang 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.84 No.-

A series of meglumine-based polysiloxane surfactants, (PSim-n) with different numbers of megluminebranches were prepared. The formed surfactants were characterized by FT-IR and NMR techniques. Physiochemical properties, such as surface activity, aggregation behavior, and wettability, were closelyexamined and used to differentiate the various samples. Thefindings demonstrate that PSim-n surfactantspossess high surface activity and can wet-out a parafilm surface at all but extremely low concentrations. Furthermore, PSi6-4, the surfactant with the highest meglumine concentration, can form larger complexaggregates in aqueous solutions.

Novel coal and siloxane based surfactants: Bola polysiloxanes modified with butynediol-ethoxylate and their properties

Pengxiao Fang,Yanyun Bai,Xiaoyuan Ma,Xiumei Tai,Wanxu Wang,Guoyong Wang 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.59 No.-

Novel polysiloxane amphiphiles obtained by introducing coal-based amphiphiles (butynediol ethoxylate) into polysiloxanes based on hydrosilylation reaction by two steps: first, synthesizing hydride terminated polysiloxane with different degree of polymerization (HTP); second, butynediol-ethoxylate was grafted on hydride terminated polysiloxane at terminals to get bola coal-based polysiloxane amphiphiles (EO-PSi-EO). In our work, EO-PSi-EO were compared together to investigate the impacts of different ratios of hydrophilic and hydrophobic groups on its properties. A conclusion was obtained from the work that EO-PSi-EO with various hydrophobic backbones have low surface tension, rich aggregate behavior, excellent wetting property and low foam.

Bioinspired spindle-knotted structure fiber membrane prepared by modified coaxial electrospinning for water-in-oil emulsion separation

Sufeng Wei,Zhengzheng Xu,Yan Liu,Yunhong Liang,Guoyong Wang 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.5

Inspired by the conformation of spider silks, fibers with multiscale spindle-knotted structures were fabricated via a one-step modified coaxial electrospinning method. Under a high-voltage electric field, hydrophobic silica polystyrene (PS) fibers coated poly (methyl methacrylate) (PMMA) fibers were integrated together during the electrospinning process. Due to the addition of hydrophobic gaseous SiO2 combining the spindle structure, a superhydrophobic fibrous membrane was prepared, and the bioinspired fibers achieved a superhydrophobic/superoleophilic performance for efficient emulsion separation. The results demonstrate that the incorporation of PS and SiO2 improved the efficiency of emulsion separation of the fabricated fibrous membranes by optimizing microstructure and wettability: Specifically, an extraordinary water contact angle under oil (162°) and a satisfied oil contact angle under water (0°). For water-in-diesel emulsions, a high separation efficiency of 99.1% was obtained for membrane with PS addition of 4 wt%, which is greater than of pure PVDF membrane with SiO2 (75.5%). It performs better than most other membranes showing strong promise in grease purification and oily wastewater treatment.