•The synergetic effects of GO and PVP on membrane performance were investigated.•The surface hydrophilicity of membrane was enhanced by the synergistic effects.•The anti-fouling performance was ...obviously improved in PVDF/GO/PVP membrane.•The optimized performance can be obtained at the stipulated GO and PVP contents.
Membrane surface and cross-sectional morphology created during membrane formation is one of the most essential factors determining membrane separation performance. However, the complicated interactions between added nanoparticles and additives influencing membrane morphology and performance during building membrane architectures had been generally neglected. In this study, asymmetric PVDF composite ultrafiltration (UF) membranes containing graphene oxides (GO) were prepared by using N-methyl pyrrolidone (NMP) as solvent and polyvinylpyrrodione (PVP) as the pore forming reagent. In the first time, the effects of mutual interactions between GO and PVP on membranes surface compositions, morphology and performance were investigated in detail. The variation in chemical properties of different membranes and hydrogen bonds in the membrane containing GO and PVP were confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Atomic force microscopy (AFM), scanning electron microscopy (SEM), and contact angle (CA) were utilized to clarify the synergetic effects of GO and PVP on morphologies and surface hydrophilicity of membranes. Besides, water flux, bovine serum albumin (BSA) rejection and attenuate coefficient were also determined to investigate filtration performance of various membranes. Compared with pure PVDF membrane, the comprehensive performance of PVDF/GO/PVP membrane has been obviously improved. The surface hydrophilicity and anti-fouling performance were enhanced by the synergistic effects of incorporated GO and PVP. When the PVP content was 0.25wt.% and the GO content was 0.5wt.%, the optimized performance can be obtained due to the formation of hydrogen bonds between GO and PVP.
The tourist experience has for a long time been one-sidedly understood as either the peak experience, or the consumer experience. For a better understanding of the tourist experience, this paper ...tries to build a conceptual model, in which both dimension of the tourist experience are integrated as a structured and interrelated whole. The position and role of each experiential component, such as eating, sleeping, transportation and so on in tourism can be more clearly understood in terms of this model. For an illustration of the model, food experience in tourism is examined in detail. It is demonstrated that food consumption in tourism can be either the peak touristic experience or the supporting consumer experience, dependent upon specific circumstances.
Contemporary environmental problems in industrial gas production and purification have driven researchers to search for green, elegant and sustainable technologies to resolve these issues. To this ...end, membrane technology is a promising and environmentally friendly alternative separation technique for mitigation of carbon dioxide (CO2) emissions in addition to gas purification for energy development (particularly from syngas, natural gas or flue gas streams). Nevertheless, traditional polymeric membranes have demonstrated insufficient capability for CO2 removal because the performance of these membranes is primarily controlled by the diffusion of various gases based on their molecular sizes. Most recently, poly(ethylene oxide) (PEO) membranes have garnered growing interest because their performance for CO2 removal can be elegantly controlled by the solubility of the different gases in the membranes. The PEO membranes have a high affinity towards CO2 and have demonstrated simplicity in membrane fabrication. However, drawbacks such as a high crystallization tendency and a weak mechanical strength have curtailed its industrial application. Various strategies have been considered to overcome these drawbacks using structural design of polymers via copolymerization with additional rigid repeating segments, crosslinking and physical blending with other polymers to produce ultra-permeable PEO-based membranes for CO2 separation. In this review, the state-of-the-art for PEO-containing membranes is evaluated alongside the benefits and shortcomings of various related methodologies. In addition, recent developments are reviewed in the fabrication of PEO-containing asymmetric and composite membranes with a thin separation layer. An assessment of the benefits and drawbacks of various approaches for fabrication of advanced PEO-containing membranes is highlighted, and future research directions in this field are also proposed.
In this study, new thin-film-composite (TFC) nanofiltration (NF) membranes were developed through interfacial polymerization (IP) on the lumen side of hollow fiber support membranes by exploring ...novel combinations of reacting monomers and optimizing the fabrication conditions. By varying the different combinations of reacting monomers, the molecular weight cut off (MWCO) of NF membranes in a hollow fiber module can be adjusted to approximately 300.0gmol−1 with a high pure water permeability of 3.1Lm−2h−1bar−1 at 3.0bar. These hollow fiber NF membranes demonstrated different rejections for different salts in the order of R(Na2SO4)>R(MgSO4)>R(NaCl)>R(MgCl2) and high pressure resistance. These membranes were further tested for the removal of typical dyes in aqueous solutions under varying conditions. For both the Safranin O and the Aniline blue dyes, the rejection was higher than 90% under the tested conditions, and the excellent performance of the NF membranes in the removal of dyes from wastewater was maintained over a wide pH range; the best performance was obtained at a pH of 11. Therefore, the novel NF membranes are promising for the removal of crucial dyes as a next-generation technology for industrial wastewater treatment.
► Hollow fiber NF membranes were developed by interfacial polymerization. ► The NF membranes exhibited excellent performance for dye removal from aqueous solutions. ► The dye removal performance was maintained over a wide range of pH values. ► The novel NF membranes are promising for industrial wastewater treatment.
This paper presents a robust controller using a Linear Parameter Varying (LPV) model of a lane-keeping system with parameter reduction. Both varying vehicle speed and roll motion on a curved road ...influence the lateral vehicle model’s parameters, such as tire cornering stiffness. Thus, we use the LPV technique to take the parameter variations into account in vehicle dynamics. However, multiple varying parameters lead to a high number of scheduling variables and cause massive computational complexity. In this paper, to reduce the computational complexity, Principal Component Analysis (PCA)-based parameter reduction is performed to obtain a reduced model with a tighter convex set. We designed the LPV robust feedback controller using the reduced model solving a set of Linear Matrix Inequality (LMI). The effectiveness of the proposed system is validated with full vehicle dynamics from CarSim on an interchange road. From the simulation, we confirmed that the proposed method largely reduces the lateral offset error, compared with other controllers based on a Linear Time-Invariant (LTI) system.
•Typical failure patterns of TLHR-CFDST columns for wind turbine towers are investigated.•Coupled mechanisms of columns under compression-bending-torsion loads and parameter effects are ...analysed.•Ultimate strength correlations of TLHR-CFDST columns for wind turbine towers are revealed.•A strength prediction method of TLHR-CFDST columns under combined loads is proposed.
Concrete-filled double-skin steel tubular (CFDST) tower has emerged as a promising type of wind turbine support structure with excellent strength and stiffness. As the basic member in CFDST towers, tapered concrete-filled double-skin steel tubular columns with large hollow ratios (TLHR-CFDSTs) are frequently subjected to complex combined compression-bending-torsion loads. This paper presents a comprehensive analytical study on the coupled behaviour of the TLHR-CFDST column under combined loads and the relevant ultimate strength prediction method. A FE model was established to conduct numerical analyses and extensive parameter studies while the data from the previous experimental research was used to provide a verification basis. It is found that the column subjected to combined loads has three typical failure patterns, which are mainly governed by the bending-to-torsion ratio (mt). Columns with moderate mt undergo the bending-torsion failure and show obvious coupled performances. The load-deformation relation, the ultimate characteristics and the effects of important parameters, including axial compressive ratio (n), tapered angle (θ), hollow ratio (χ) and height-to-diameter ratio (λ) were discussed. The ultimate strength correlations of the column were revealed by analysing strength data within the parameter scopes commonly used in wind turbine towers. Lastly, a practical and accurate prediction method for the ultimate strength of the TLHR-CFDST column under combined compression-bending-torsion loads was proposed.
The accretionary complex of the Yarlung Zangbo Suture Zone (YZSZ) in southern Tibet records the subduction-accretion process of Neo-Tethys oceanic lithosphere. We report field observations, ...petrographic analysis, detrital zircon U-Pb geochronology, and Hf isotope data of one sedimentary-matrix mélange unit of YZSZ in Sangsang area, central southern Tibet. This mélange unit is the northernmost, and presumably the oldest one within the YZSZ accretionary complex. The sandstone matrix and blocks are rich in volcanic detritus, linking the main provenance to a juvenile magmatic arc. U-Pb-Hf analysis of detrital zircons from the sandstones reveals a unimodal age population of ~186–121 Ma with high positive εHf(t) values of +6.67 to +14.58, consistent with derivation from Gangdese Arc on southern margin of Lhasa terrane. The maximum depositional age of the mélange unit is limited to be 149–134 Ma by averaging the youngest detrital zircon ages. The sandstones of this mélange unit probably deposited in the trench basin within a few million years of early accretion driven by the Neo-Tethys oceanic subduction. The development of arc-trench system verified the initiation of subduction of Neo-Tethys oceanic lithosphere in Early Jurassic. Our results and integration of previous studies on subduction-accretion process of Neo-Tethys subduction indicate that the accretionary complex in Sangsang area documented at least two stages of accretion processes, stage 1 in earliest Cretaceous and stage 2 in Late Cretaceous, separated by a period of forearc extension forming the Yarlung Zangbo Ophiolites. These two stages of accretion correspond to growth and erosion of Gangdese Arc and crustal shortening in southern Eurasian margin.
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•Accretion of Neo-Tethys oceanic subduction formed accretionary complex in Sangsang.•Sandstones of the oldest Sangsang complex unit were deposited in trench basin.•First stage of accretion of Neo-Tethys subduction occurred later than 149–134 Ma.•Neo-Tethys oceanic subduction was initiated earlier than 183 Ma.
•Spin transport is studied in a 3-layered semiconductor heterostructure.•An obvious spin polarization appears due to Dresselhaus SOC.•Spin polarization is modulated by strain engineering or ...intermediate layer.•The 3-layered semiconductor heterostructure can be used as a controllable spin filter.
Considering Dresselhaus-type spin–orbit coupling (SOC), we theoretically investigate spin-polarized transport in a 3-layered semiconductor heterostructure, InSb/InxGa1-xAs/GaSb. Adopting improved transfer matrix method to solve Schrödinger equation, electronic transmission coefficient is obtained exactly, and then spin polarization ratio is evaluated. An appreciable electron-spin polarization effect by the Dresselhaus-SOC appears in this layered semiconductor heterostructure. Spin polarization is associated closely with in-plane wave vector, incident direction and SOC strength. In particular, both magnitude and sign of spin polarization are manipulated by strain engineering or an appropriate intermediate-layer. Therefore, such a 3-layered semiconductor heterostructure can serve as a controllable spin filter for spintronics device applications.
We calculate dwell time spent by electron in a hybrid magnetic-electric-barrier semiconductor microstructure, which can be experimentally realized by patterning a ferromagnetic (FM) stripe and a ...Schottky metal (SM) stripe on top and bottom of InAs/Al
x
In
1-x
As heterostructure, respectively. The dwell time is closely related to electron spins due to the interaction between electron spins and structural magnetic fields, which makes possible separation of electron spins in time dimension. The spin-polarized dwell time can be controlled by rationally constructing the SM stripe, which may lead to a controllable temporal spin splitter for spintronics device applications.
