Adaptive control of a vehicle-seat-human coupled model using quasi-zero-stiffness vibration isolator as seat suspension

We propose the quasi-zero-stiffness (QZS) vibration isolator as seat suspension to improve vehicle vibration isolation performance. The QZS vibration isolator is composed of vertical spring and two symmetric negative stiffness structures used as stiffness correctors. A vehicle-seat-human coupled model considering the QZS vibration isolator is established as a three degree-of-freedom (DOF) model; it is composed of a quarter car model and a simplified 1 DOF model combined vehicle seat and human body. This model considers the changing mass of the passengers and sets the total mass of the vehicle seat and human body as an uncertain parameter, which investigates the overload and unload conditions in practical engineering. To further improve the vehicle ride comfort, a constrained adaptive backstepping controller law based on the barrier Lyapunov function (BLF) is presented. The dynamic characteristic of the active vehicle-seathuman coupled model under shock excitation was analyzed using numerical method. The results show that the designed controller law can isolate the shock excitation transmitted from the road to the passengers effectively, and both the vehicle and seat suspension strokes remain in the allowed stroke range.     

Toward multiple maximum power point estimation of photovoltaic systems based on semiconductor theory

Environmental conditions, such as temperature, non‐uniform irradiation, and solar shading, deeply affect the characteristics of photovoltaic (PV) modules in PV‐assisted generation systems. Several local maximum power points (MPPs) are found in the power–voltage curve of PV systems constructed by series/parallel‐connected PV modules under partially shaded conditions. The characteristics of PV systems change unpredictably when multiple MPPs occur, so the actual MPP tracking (MPPT) becomes a difficult task. Conventional MPPT methods for the PV systems under partially shaded conditions cannot quickly find the actual MPP such that the optimal utilization of PV systems cannot be achieved. Based on the p–n junction semiconductor theory, we develop a multipoint direct‐estimation (MPDE) method to directly estimate the multiple MPPs of the PV systems under partially shaded conditions and to cope with the mentioned difficulties. Using the proposed MPDE method, the multiple MPPs of the PV systems under partially shaded conditions can be directly determined from their irradiated current–voltage and power–voltage characteristic curves. The performances of the proposed MPDE method are evaluated by examining the characteristics of multiple MPPs of PV systems with respect to different shading strengths and numbers of the shaded PV modules and also tested using the field data. The experimental results demonstrate that the proposed MPDE method can simply and accurately estimate the multiple MPPs of the PV systems under partially shaded conditions. The optimization of MPP control models and the MPPT for PV systems could be achieved promisingly by applying the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.     

聚乙二醇改性脱除煤沥青中3,4-苯并芘

以聚乙二醇为改性剂,研究在溶剂条件下降低煤沥青中3,4-苯并芘的工艺。研究表明,当混合溶剂V环己烷∶V甲苯=2∶1为反应溶剂、硫酸用量为煤沥青质量的6.67%、聚乙二醇600用量为煤沥青质量的10%、反应温度为80℃、反应时间为5h时,3,4-苯并芘降低率为85.59%。     

硅胶表面罗丹明B分子印迹聚合物的制备及其性能研究

以表面接枝乙烯基的硅胶为载体,罗丹明B为模板分子,丙烯酰胺为功能单体,乙二醇二甲基丙烯酸酯为交联剂,制备了表面印迹聚合物微球。通过静态吸附对吸附性能进行分析。结果表明,该印迹聚合物对模板分子具有特异吸附性能,并将其应用于固相萃取,测得罗丹明B的加标回收率为94.4%~101.2%,相对标准偏差(n=3)的范围为2.4%~3.4%。     

无卤阻燃增强硬质聚氨酯泡沫塑料的研究

采用聚醚多元醇、聚酯多元醇、多异氰酸酯、泡沫稳定剂、催化剂及发泡剂等为基本原料,以聚磷酸铵(APP)、可膨胀石墨(EG)及膨润土(BT)为阻燃剂及填料,通过一步发泡法制备了无卤阻燃增强硬质聚氨酯泡沫塑料。研究了APP、EG、BT对泡沫力学性能、阻燃性能以及泡孔结构的影响。结果表明,APP质量分数为15%,EG为7.5%,膨润土为2.5%时可以制得力学性能和阻燃性能均优良的聚氨酯泡沫塑料。在该条件下,泡沫的压缩强度为0.271 MPa,平均孔径为322μm,极限氧指数达到29.5%。     

Controlled delivery of growth‐hormone‐releasing peptide 6 from the poly(lactic‐co‐glycolic acid)–poly(ethylene glycol)–poly(lactic‐co‐glycolic acid) copolymer and the effect of a growth‐hormone‐releasing peptide 6–copolymer hydrogel on the growth of rex rabbits

Growth‐hormone‐releasing peptide 6 (GHRP‐6) plays an important role in animal growth. However, there have been few studies focusing on the effect of GHRP‐6 on animal growth through controlled release systems. We synthesized the poly(lactic‐co‐glycolic acid) (PLGA)–poly(ethylene glycol) (PEG)–PLGA copolymer to investigate its controlled released effect on GHRP‐6 in vitro and to study the effect of a GHRP‐6–copolymer hydrogel on the growth of rex rabbits. The copolymer was synthesized with ring‐opening copolymerization and characterized by ¹H‐NMR. The interaction between GHRP‐6 and the copolymer was characterized by Fourier transform infrared spectroscopy and X‐ray diffraction. The body weight, serum level of insulin‐like growth factor 1 (IGF‐1), and hair coat quality were studied in rex rabbits. The results show that hydrogen bonds formed between the N? H group in GHRP‐6 and the C?O group in the copolymer. The release mechanism of GHRP‐6 was a combination of a diffusion‐controlled mechanism and an erosion‐controlled mechanism in the copolymer. The serum level of IGF‐1, hair coat quality, and body weight were all significantly higher in the GHRP‐6–copolymer hydrogel group than in the other groups. These results indicate that the copolymer effectively controlled the release of GHRP‐6. In addition, the GHRP‐6–copolymer hydrogel increased the synthesis of IGF‐1 for a prolonged period and, thereby, increased the rex rabbits' growth and hair coat quality. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40185.     

pH and temperature responsive porous membranes via an in situ bulk copolymerization approach

In the present study, an in situ approach to pH and temperature responsive membranes is developed. The membrane matrix is formed through bulk polymerization and crosslinking of liquid monomer 2-hydroxyethyl methacrylate (HEMA) while the membrane pores are formed by the templating of inorganic particles. The functional monomers methacrylic acid (MAA) and N-isopropylacrylamide (NIPAAm) are incorporated into membrane casting solution in order to confer membranes with pH and temperature responsive properties. The poly(HEMA/MAA) membranes exhibit a reversible pH-dependent water flux, while the poly(HEMA/NIPAAm) membranes exhibit a reversible temperature-dependent water flux. The flux of the poly(HEMA/MAA) membrane increased by 70% when pH was decreased from 10.0 to 2.0, while the flux poly(HEMA/NIPAAm) membrane increased by 150% when temperature was increased from 20 to 45 °C. The protein adsorption and antifouling performance of the poly(HEMA/MAA) and poly(HEMA/NIPAAm) membranes also exhibit pH and temperature responsive properties.     

Biomimetic and bioinspired membranes: Preparation and application

By imitating the exceptional compositions, structures, formations and functions of biological or natural materials, a myriad of biomimetic and bioinspired membranes have been designed and prepared using cell membrane, lotus, mussel as representative prototypes and biomineralization, bioadhesion, self-assembly as major tools. These membranes have displayed fascinating properties and outstanding performances such as multiple interactions, hierarchical organizations, multiple selective transport mechanisms, superior stability/resistance and distinct adaptability. Meanwhile, these membranes have made tremendous contributions in coping with energy and water stress, environment threats. Biomimetics focuses on the basic science by fundamentally exploring the principles of biological systems, while bioinspiration focuses on the applied engineering by technologically implementing the principles from biological systems. Biomimetics and bioinspiration, as the complementary and interchangeable strategies for sustainable innovation and development of membrane technology, have great implications in exploring membrane materials and intensifying membrane processes. This review will present a brief overview on the prototypes, preparation, application as well as perspective of biomimetic and bioinspired membranes.     

Doubly thermo-responsive brush-linear diblock copolymers and formation of core-shell-corona micelles

Doubly thermo-responsive brush-linear diblock copolymer of poly[poly(ethylene glycol) methyl ether vinylphenyl]-block-poly(N-isopropylacrylamide) (PmPEGV-b-PNIPAM) is prepared by RAFT polymerization. The obtained brush-linear diblock copolymer exhibits two lower critical solution temperatures (LCSTs) corresponding to the linear poly(N-isopropylacrylamide) (PNIPAM) block and the brush poly[poly(ethylene glycol) methyl ether vinylphenyl] (PmPEGV) block in water. This brush-linear diblock copolymer undergoes a two-step temperature sensitive micellization. At temperature above the first LCST, the brush-linear diblock copolymer self-assembles into core-corona micelles with the dehydrated PNIPAM block forming the core and the solvated brush PmPEGV block forming the corona. When temperature increases above the second LCST, the polystyrene backbone in the brush PmPEGV block collapses onto the dehydrated PNIPAM core to form core-shell-corona micelles, in which the dehydrated PNIPAM block forms the core, the collapsed polystyrene backbone in the brush PmPEGV block forms the shell and the solvated poly(ethylene glycol) side-chains forms the corona. The effect of the length of the PNIPAM block and the length of the poly(ethylene glycol) side-chains on the thermo-responsive micellization and the size of core-shell-corona micelles is investigated.     

Preparation and physical properties of an epoxy nanocomposite with amine‐functionalized graphenes

Graphene, consisted of a single layer of carbon atom in a two‐dimensional lattice, has superior electrical and physical properties that promise many exciting applications. In this study, graphenes were prepared from graphite powder by chemical method and their images were investigated by TEM and SEM. To develop high performance epoxy nanocomposites with good dispersion of graphenes and strong epoxy‐graphene interfacial bonding, graphenes were amine‐functionalized and the effects of the amine‐functionalization on the curing behavior and physical properties of epoxy/graphene nanocomposites were studied. FTIR spectra confirmed the amine‐functionalization. The physical properties of the nanocomposites were investigated by DSC, DMA, TMA, and impact tester. Fracture surfaces were investigated by SEM. The physical properties of the nanocomposites could be improved considerably by the amine‐functionalization of graphenes. POLYM. ENG. SCI., 54:985–991, 2014. © 2012 Society of Plastics Engineers