Particle swarm optimization-based algorithm of a symplectic method for robotic dynamics and control

Multibody system dynamics provides a strong tool for the estimation of dynamic performances and the optimization of multisystem robot design. It can be described with differential algebraic equations(DAEs). In this paper, a particle swarm optimization(PSO) method is introduced to solve and control a symplectic multibody system for the first time. It is first combined with the symplectic method to solve problems in uncontrolled and controlled robotic arm systems. It is shown that the results conserve the energy and keep the constraints of the chaotic motion, which demonstrates the efficiency, accuracy, and time-saving ability of the method. To make the system move along the pre-planned path, which is a functional extremum problem, a double-PSO-based instantaneous optimal control is introduced. Examples are performed to test the effectiveness of the double-PSO-based instantaneous optimal control. The results show that the method has high accuracy, a fast convergence speed, and a wide range of applications.All the above verify the immense potential applications of the PSO method in multibody system dynamics.

Solvent-free Synthesis,Crystal Structure and Thermal Stability of Ionic Liquid 1-Hexadecyl-3-methylimidazolium Bromide

Ionic liquid 1-hexadecyl-3-methylimidazolium bromide [C16mim]Br was synthesized by solvent-free alkylation of N-methylimidzole with hexadecyl bromide. A large transparent single crystal of 1-hexadecyl-3-methylimidazolium bromide monohydrate （[C16mim]Br·H2O）, 4 mm in length, was firstly obtained in the water-trichloromethane-toluene growth system （Vwater＇Vtrichloromethane＇Vtoluene = 0.1：1：2）. The crystal structure was determined by single-crystal X-ray diffraction method. It crystallizes in the triclinic system, space group P1, with a = 5.4962（15）, b = 7.839（2）, c = 27.279（8） A, α = 94.375, β = 91.500, γ = 101.999°, Z = 2, V = 1145.2（5） A3, C20H41BrN2O, Mr = 405.46, Dc = 1.176 Mg/m3, μ = 1.804 mm^-1, F（000） = 436, the final R = 0.0523 and wR = 0.1345. The 3D supramolecular structure is constructed through weak interactions between imidazolium cations, Br- anions and lattice water molecules. The long alkyl chain to the imidazolium ring and lattice water molecules play an important role in the self-assembly process. Moreover, it is proposed that [C16mim]Br in water has aggregation behavior and the possible self-assembled structure is the interdigitated pattern. Finally, thermal stability of [C16mim][Br]·H2O was also studied by DSC and TGA analysis.

Influence of Structural Variations on Electrical Conductivity and Solubility of 1-Vinyl-3-alkylimidazole Halogen Ionic Liquids

Several 1-vinyl-3-alkylimidazolium halogens [VRIM]X, which are functional materials with ethylenic bonds, were synthesized using the microwave-assisted synthesis method. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy were carded out to analyze the resultant structures. The electrochemical properties and solubility of [VRIM]Br were investigated and discussed in detail. The temperature dependence of pure [VRIM]Br over a wide temperature range of 298.15-323.15 K fitted the Arrhanius equation well. At certain low concentrations, the electrical conductivity of the [VRIM]Br solution significantly increased with increasing solution concentration. The electrical conductivities of the [VRIM]Br observed in water, methanol, and ethanol showed the trend σwater〉 σmethanol 〉σethanol Conductometry showed that the critical miceUe concentrations of the bromines in water, methanol, and ethanol were 6.8-6.9 × 10-6, 1.4-1.5 × 10-5, and 1.9-2.0×10-5 mol.L-1, respectively; these results indicate that [VRIM]Br is an excellent surfactant. The solubility of [VRIM]X in common solvents was determined at 293.15 K, and results indicated that a decrease in solubility could be observed with decreasing dielectric constant of the solvent, elongation of the alkyl chain of the cation, and increasing anion size. Solubility parameters were also determined according to the Hildebrand-Scoff equation.

Synthesis and Physicochemical Properties of L-(+)-a-(Positive Butyl)-Leucine Ethyl Ester Chiral Ionic Liquids

L-（＋）-α-（positive butyl）-leucine ethyl ester bromide chiral ionic liquid was synthesized by using microwave-assisted synthesis method and L-（＋）-α-（positive butyl）-leucine ethyl ester terafluoroborate and hexafluorophosphate chiral ionic liquids were synthesized by the anion exchange reaction. The structures were characterized by IR, ~1HNMR and structure optimization calculation. The results of studies on physicochemical properties show that they possess better thermal stability, solubility, bio-solubility and high conductivity. They can serve as effective reaction media as well as chiral catalysts. They are presently being investigated as dispersion agents in molecular imprinting ployer.

Highly Improved Microstructure and Properties of Poly(p-phenylene terephthalamide) Paper-based Materials via Hot Calendering Process

In this study,the effect of hot calendering process on the microstructure and properties of poly(p-phenylene terephthalamide)(PPTA) paper-based materials was investigated.The microstructures of the fracture surface,crystalline structure,and single fiber strength of the PPTA paperbased materials as well as the different bonding behaviors between the PPTA fibers and PPTA fibrids obtained before and after the hot calendering process were examined.The results indicated that a high linear pressure would result in a limited improvement of the strength owing to the unimproved paper structure.The optimal values of tensile index and dielectric strength of 56.6 N·m/g and 27.6 kV/mm,respectively,could only be achieved with a synergistic effects of hot calendering temperature and linear pressure(240℃ and 110 k N/m,respectively).This result suggested it was possible to achieve a significant reinforcement and improvement in the interfacial bonding of functional PPTA paper-based materials,and avoid the formation of unexpected pleats and cracks in PPTA paper-based materials during the hot calendering process.

Splitting light beam by meanderline with continuous phase profile

It has been successfully demonstrated can be widely used in nano-photonics applications owing to their flexible wavefront manipulation in a limited physical profile.However,how to improve the efficiency for the transmission light is still a challenge.We experimentally demonstrate that the sine-shaped metallic meanderline fabricated by focus ion beam technology converts circularly polarized(CP)light to its opposite handedness and sends them into different propagation directions depending on the polarization states in near-infrared and visible frequency regions.The beam splitting behavior is well characterized by a simple geometry relation,following the rule concluded from other works on the wavefront manipulation of metasurface with phase discontinuity.Importantly,the meanderline is demonstrated to be more efficient in realizing the same functions due to the suppressed high order diffractions resulted from the absence of interruption in phase profile.The theoretical efficiency reaches 67%.Particularly,potential improvements are feasible by changing or optimizing shape of the meanderline,offering high flexibility in applications for optical imaging,communications and other phase-relative techniques.Additionally,since the continuous phase provided by the meanderline can improve the sampling efficiency of the phase function,it is helpful in realizing high quality hologram.

Synthesis and Characterization of a Novel Graphene Oxide/titanium Dioxide Solvent-free Nanofluid

A novel graphene oxide/titanium dioxide（GO/TiO2） solvent-free nanofluid was firstly synthesized by employing GO, which was in-situ deposited by TiO2 as the core and（3-Glycidyloxypropyl） trime thoxysilane（KH560） and polyetheramine-M2070 as the shell. The morphology and structure of GO/TiO2 nanofluid were verified by Transmission electron microscopy（TEM）, X-ray diffraction（XRD） analysis, Fourier transform infrared spectroscopy（FTIR）, X-ray photoelectron spectroscopy（XPS） and UV-vis absorption spectra. These studies confirmed that TiO2 has been deposited onto GO with good dispersion, and the organic shell has been grafted onto the core successfully. Thermo gravimetric analysis（TGA） and viscosity analysis indicated that this nanoparticle hybrid material presented a liquid state without solvent at room temperature, and has great fluidity and thermal stability. The solubility investigation of GO/TiO2 nanofluid revealed its excellent amphiphilicity and the potential as the functional nanocomposites.

Controlling the Properties of Solvent-free Fe_3O_4 Nanofluids by Corona Structure

We studied the relationship between corona structure and properties of solvent-free Fe3O4 nanofluids. We proposed a series of corona structures with different branched chains and synthesize different solvent-free nanofluids in order to show the effect of corona structure on the phase behavior, dispersion, as well as rheology properties. Results demonstrate novel liquid-like behaviors without solvent at room temperature. Fe3O4 magnetic nanoparticles content is bigger than 8% and its size is about 23 nm. For the solvent-free nanofluids,the long chain corona has the internal plasticization, which can decrease the loss modulus of system, while the short chain of corona results in the high viscosity of nanofluids. Long alkyl chains of modifiers lead to lower viscosity and better flowability of nanofluids. The rheology and viscosity of the nanofluids are correlated to the microscopic structure of the corona, which provide an in-depth insight into the preparing nanofluids with promising applications based on their tunable and controllable physical properties.

Robustness of iterative learning control for a class offractional-order linear continuous-time switched systems in the sense of L^p norm

For a class of fractional-order linear continuous-time switched systems specified by an arbitrary switching sequence,the performance of PDα-type fractional-order iterative learning control(FOILC)is discussed in the sense of L^p norm.When the systems are disturbed by bounded external noises,robustness of the PDα-type algorithm is firstly analyzed in the iteration domain by taking advantage of the generalized Young inequality of convolution integral.Then,convergence of the algorithm is discussed for the systems without any external noise.The results demonstrate that,under some given conditions,both convergence and robustness can be guaranteed during the entire time interval.Simulations support the correctness of the theory.

Effect of stochastic electromagnetic disturbances on autapse neuronal systems

With the help of a magnetic flux variable, the effects of stochastic electromagnetic disturbances on autapse Hodgkin–Huxley neuronal systems are studied systematically. Firstly, owing to the autaptic function, the inter-spike interval series of an autapse neuron not only bifurcates, but also presents a quasi-periodic characteristic. Secondly, an irregular mixed-mode oscillation induced by a specific electromagnetic disturbance is analyzed using the coefficient of variation of inter-spike intervals. It is shown that the neuronal discharge activity has certain selectivity to the noise intensity, and the appropriate noise intensity can induce the significant mixed-mode oscillations. Finally, the modulation effects of electromagnetic disturbances on a ring field-coupled neuronal network with autaptic structures are explored quantitatively using the average spiking frequency and the average coefficient of variation. The electromagnetic disturbances can not only destroy the continuous and synchronous discharge state, but also induce the resting neurons to generate the intermittent discharge mode and realize the transmission of neural signals in the neuronal network. The studies can provide some theoretical guidance for applying electromagnetic disturbances to effectively control the propagation of neural signals and treat mental illness.

Ab initio molecular dynamics simulations of nano-crystallization of Fe-based amorphous alloys with early transition metals

The addition of early transition metals（ETMs） into Fe-based amorphous alloys is practically found to be effective in reducing the α-Fe grain size in crystallization process. In this paper, by using ab initio molecular dynamics simulations, the mechanism of the effect of two typical ETMs（Nb and W） on nano-crystallization is studied. It is found that the diffusion ability in amorphous alloy is mainly determined by the bonding energy of the atom rather than the size or weight of the atom. The alloying of B dramatically reduces the diffusion ability of the ETM atoms, which prevents the supply of Fe near the grain surface and consequently suppresses the growth of α-Fe grains. Moreover, the difference in grain refining effectiveness between Nb and W could be attributed to the larger bonding energy between Nb and B than that between W and B.

Analysis of the Electronic Structure of 1-(4-Aminobutyl)-3-methylimidazolium Chloride via DFT Method

Density functional theory and natural bond orbital analysis are applied to study the microelectronic structural properties of 1-(4-aminobutyl)-3-methylimidazolium chloride(C_4NH_2C_1imCl). We obtain 48 stable cation conformers at the B3LYP/6-311++G(d, p) level of theory. When the Cl anion is located at different positions around the two stable cation conformers,optimization and frequency are calculated at the same level of theory, and seven stable C_4NH_2C_1imCl structures are obtained. Ion-pair association energies, natural population analysis(NPA) charges, and the second-order stabilization energies are also calculated. Results show that three energy-degenerated states are present in seven conformers. The calculated ion-pair association energy, NPA charges, and second-order stabilization energy values are the same as those with the same energy level conformers. Finally, H bond formation in the molecule is analyzed by the interactions of frontier molecular orbitals. The lone pair of N(11) atom in the amino group exhibits higher reactivity than that of the N(4) atom in the ring.

A density functional theory study on parameters fitting of ultra long armchair(n,n) single walled boron nitride nanotubes

Armchair （n, n） single walled boron nitride nanotubes with n = 2-17 are studied by the density functional theory at the B3LYP/3-21G（d） level combined with the periodic boundary conditions for simulating the ultra long model. The results show that the structure parameters and the formation energies bear a strong relationship to n. The fitted analytical equations are developed with correlation coefficients larger than 0.999. The energy gaps of （2, 2） and （3, 3） tubes are indirect gaps, and the larger tubes （n = 4-17） have direct energy gaps. Results show that the armchair boron nitride nanotubes （n = 2-17） are insulators with wide energy gaps of between 5.93 eV and 6.23 eV.

Adsorptive Removal of Reactive Dye from Water by Modified Montmorillonite

Polyaniline-intercalated montmorillonite( PANI-MMT)was prepared via in-situ intercalative polymerization and used as the adsorbent for the removal of reactive green 19( RG-19) dye from water. The structure,composition and specific surface area of asprepared composite were characterized using Fourier transform infrared spectroscopy( FT-IR),X-ray diffraction( XRD) and surface area analyzer. The adsorption of RG-19 by PANI-MMT was investigated as a function of contact time,temperature and pH. The results indicated the adsorption kinetics of RG-19 onto PANI-MMT followed the pseudo second-order model best among the pseudo firstorder,pseudo second-order and Elovich kinetic models. The equilibrium data fitted the Langmuir model better than the Freundlich model. Moreover,the maximum adsorption capacity for RG-19 decreased with the increase of initial solution pH. It can be concluded that the PANI-MMT can be a potential adsorbent for RG-19 removal from water.

Electrical activities of neural systems exposed to sinusoidal induced electric field with random phase

The brain neural system is often disturbed by electromagnetic and noise environments, and research on dynamic response of its interaction has received extensive attention. This paper investigates electrical activity of Morris-Lecar neural systems exposed to sinusoidal induced electric field(IEF) with random phase generated by electromagnetic effect. By introducing a membrane depolarization model under the effect of random IEF, transition state of firing patterns, including mixed-mode oscillations(MMOs) with layered inter-spike intervals(ISI) and intermittency with a power law distribution in probability density function of ISI, is obtained in a single neuron. Considering the synergistic effects of frequency and noise, coherence resonance is performed by phase noise of IEF under certain parameter conditions. For the neural network without any internal coupling, we demonstrate that synchronous oscillations can be induced by IEF coupling, and suppression of synchronous spiking is achieved effectively by phase noise of IEF. Results of the study enrich the dynamical response to electromagnetic induction and provide insights into mechanisms of noise affecting information coding and transmission in neural systems.

Distribution and Transport of Residual Lead and Copper Along Soil Pro?les in a Mining Region of North China

Residual heavy metals are commonly considered to be immobile in soils,leading to an underestimation of their environmental risk.This study investigated the distribution and transport of residual heavy metals along soil pro?les,using the Xiaoqinling gold mining region in North China as a case study.Soil samples were collected at three depths from three locations near the tailing heap.The speciation of copper(Cu) and lead(Pb)(exchangeable,carbonate-bound,Fe-Mn oxide-bound,organic matter-bound,and residual fractions) was determined using a sequential extraction procedure.The residual fraction's morphology was observed using scanning electron microscopy(SEM).Results showed that metal fraction distributions along the soil pro?les were in?uenced by each fraction's mobility.Residual fraction with high chemical stability can not be transformed from or into other fractions.This led to the conclusion that the high concentration of residual metals in soils mainly resulted from residual fraction transport.The SEM analysis showed that ?ne particles(submicrons) were mainly attached to large particles and were likely released and transported by water?ow.The more sorptive fractions(non-residual fractions) were mainly retained in the top soil,and the more mobile fractions(residual fraction) were mainly leached to the deep soil.Cu and Pb concentrations in the residual fraction decreased slightly and those in the non-residual fractions decreased signi?cantly with soil depth.These suggest a relatively higher residual metal mobility along the soil pro?les.Therefore,residual metals can be transported in soils and their environmental risk can not be ignored in assessing soil contamination.

Preparation of Close-Packed Silver Nanoparticles on Graphene to Improve the Enzyme Immobilization and Electron Transfer at Electrode in Glucose/O2 Biofuel Cell

In this study, chemical reduced graphene-silver nanoparticles hybrid （AgNPs@CR-GO） with close-packed AgNPs structure was used as a conductive matrix to adsorb enzyme and facilitate the electron transfer between im- mobilized enzyme and electrode. A facile route to prepare AgNPs@CR-GO was designed involving in β-cyclodextrin （β-CD） as reducing and stabilizing agent. The morphologies of AgNPs were regulated and controlled by various experimental factors. To fabricate the bioelectrode, AgNPs@CR-GO was modified on glassy carbon electrode followed by immobilization of glucose oxidase （GOx） or laccase. It was demonstrated by electrochemical testing that the electrode with close-packed AgNPs provided high GOx loading （Г=4.80 × 10^- l0 mol·cm^-2） and fast electron transfer rate （ks=5.76 s^-1）. By employing GOx based-electrode as anode and laccase based-electrode as cathode, the assembled enzymatic biofuel cell exhibited a maximum power density of 77.437 μW·cm^-2 and an open-circuit voltage of 0.705 V.

Novel N-methylimidazolium Chiral Ionic Liquids with Esterfunction Functionality in Cation

Using （S）-（-）-2-chloropropionie acid ethyl ester and N-methylimidazole as raw materials, we designed and synthesized three N-methylimidazolium chiral ionic liquids by the nucleophilic substitution reaction or anion exchange reaction. These chiral ionic liquids structures were analyzed with structure optimization calculation, IR, and HNMR. Their reaction mechanism and physical chemistry properties were explored. As a result, these chiral ionic liquids possess optical activity, low melting point, high conductivity, and weak acidity, etc. They can serve as effective reaction media as well as chiral catalysts. They are presently being investigated as dispersion agent in molecular imDrinting, nlover in our laboratory.

Synthesis of PP-g-PIP and Properties of PP/PP-g-PIP Binary Blends

The polypropylene-grafl-polyisoprene （PP-g-PIP） copolymers with different side chain length were synthesized by the combination of solid phase graft and anionic polymerization. The copolymers were characterized by nuclear magnetic resonance spectrum （1H-NMR）, gel permeation chromatography （GPC） and differential scanning calorimetry （DSC）. Five PP/PP-g-PIP blends with PP-g-PIP as a flexibilizer to toughen PP were prepared and characterized by scanning electron microscope （SEM）, dynamic mechanical analysis （DMA）, DSC, wide-angle X-ray diffraction （WAXD）. Their morphologies, glass transition temperatures, crystallinity and mechanical properties were investigated. All the results pointed out that the covalent bonding of PP and PIP increased the compatibility and interfacial adhesion, which led to PIP well dispersed in the system and small size PIP particles in the binary blends. In addition, the toughness of PP was improved while its tensile strength slightly decreased.

Synthesis of Liquid-like Trisilanol Isobutyl-POSS NOHM and Its Application in Capturing CO2

The trisilanol isobutyl polyhedral oligomeric silsesquioxane（POSS） was fabricated into liquid-like nano- particle organic hybrid materials（NOHMs） with ）,-（2,3-epoxypropoxy）propytrimethoxysilane as corona and polyethe- ramine M2070 as canopy, and the product was called liquid-like POSS NOHM. The liquid-like POSS NOHM has a low viscosity at room temperature without any solvent and the mass fraction of trisilanol isobutyl POSS was 23.38%. The liquid-like POSS NOHM shows great CO2 capturing property with a capacity of 2.108 mmol/g（PCO2=6 MPa）. The physical adsorption increased obviously with the pressure going up and it may make a difference between liquid-like POSS NOHMs and traditional monoethamolamine（MEA） based CO2 absorbent. The recycle property was also studied. The NOHM behaved as fresh product even after 10 cycles.