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A novel concept of distributed temperature–strain sensors is proposed using inter-mode Kerr four-wave mixing of polarization-maintaining fiber (PMF), in which the dominated physical mechanism is basically different from reported Brillouin dynamic grating (BDG). The independent measurement for temperature and strain sensitivities (−0.431 MHz °C−1 and 0.067 MHz/10 με) was completed by detecting the change in birefringence under pump-Stokes frequency separation at 370 MHz. As a preliminary proof-of-concept, sensing with a spatial resolution of ∼5 m was demonstrated along ∼210 m PMF. Compared with BDG, the proposed sensor features potential of multiple parameters measurement including temperature–strain and liquid acoustic impedance.

Via implementing parallel tasks including Santa-Fe time series prediction and nonlinear channel equalization, we studied the characteristics of reservoir computing (RC) using two mutually-coupled semiconductor lasers (MC-SLs) with optoelectronic feedback. The influence of system parameters (injection current, coupling strength, scaling factor and coupling time-delays) on RC performance have been investigated in detail. Results show that, the optimized performance is always achieved around the edge of bifurcation points; positive feedback is more preferred when the scaling factor exceeds a certain level; under optimized parameters, both of lower normalized mean squared error (NMSE) and symbol error rate (SER) can be achieved to perform parallel tasks, due to the richer dynamics and states of virtual nodes. The effect of system parameters on RC performance was also discussed. Our study would be helpful for the design and optimization of proposed parallel RC with optoelectronic feedback.

Distributed fiber sensors based on forward stimulated Brillouin scattering (F-SBS) have attracted special attention because of their capability to detect the acoustic impedance of liquid material outside fiber. However, the reported results were based on the extraction of a 1st-order local spectrum, causing the sensing distance to be restricted by pump depletion. Here, a novel post-processing technique was proposed for distributed acoustic impedance sensing by extracting the 2nd-order local spectrum, which is beneficial for improving the sensing signal-to-noise ratio (SNR) significantly, since its pulse energy penetrates into the fiber more deeply. As a proof-of-concept, distributed acoustic impedance sensing along ∼ 1630 m fiber under moderate spatial resolution of ∼ 20 m was demonstrated.

Simultaneous bandwidth (BW) enhancement and time-delay signature (TDS) suppression of chaotic lasing over a wide range of parameters by mutually coupled semiconductor lasers (MCSLs) with random optical injection are proposed and numerically investigated. The influences of system parameters on TDS suppression (characterized by autocorrelation function (ACF) and permutation entropy (PE) around characteristic time) and chaos BW are investigated. The results show that, with the increasing bias current, the ranges of parameters (detuning and injection strength) for the larger BW (> 20 GHz) are broadened considerably, while the parameter range for optimized TDS (< 0.1) is not shrunk obviously. Under optimized parameters, the system can simultaneously achieve two chaos outputs with enhanced BW (> 20 GHz) and perfect TDS suppression. In addition, the system can generate two-channel high-speed truly physical random number sequences at 200 Gbits/s for each channel.

In the present paper, pCBT casts and pCBT/E-glass fiber composites were prepared. In order to study the mechanical performance of the thermoplastic material in the aging environment, the specimens were exposed to salt spray, hygrothermal as well as immersion conditions. The hygroscopicity and mechanisation of the material were studied. From this research work, it is found that, in corrosion tests, the water absorb rate increases at the beginning of the test and decreases with the increase of time. Chloride ion concentrationb and a higher corrosion time have some influence on the moisture absorption kinetics. The results also show that the mechanical properties such as modulus and strength of pCBT and its glass fiber composites change with the trendency of moisture absorption curves.

Shape memory polymers (SMPs) have drawn wide attention of many researchers for its potential applications to shipping industry, aerospace, bionics engineering and mechanical engineering. Shape memory polymers composites (SMPCs) have ability to improve the properties and obtain attain new functions of shape memory polymers. In this paper, trans-1, 4-polyisoprene reinforced by carbon fiber is developed to improve the mechanical weakness of trans-1, 4-polyisoprene bulk. Composites with carbon fiber weight fraction of 5%, 10%, and 15% are fabricated by casting samples with an average length of 2 mm. The mechanical property of the trans-1, 4-polyisoprene reinforced by short carbon fiber is evaluated and the effects of short carbon fiber on shape memory behavior are investigated. The results indicate that there is an optimum fiber weight fraction between 5 and 15 wt% where exists an extremely low recovery ratio, re-crystallizing temperatures (Tc) and an extremely high tensile stress.

The stress and strain field near the tip of Mode I growing crack in materials under creep conditions is examined. The case of the effective stress equal to zero is considered. The asymptotic equations for the crack of the crack tip field are derived and solved numerically. It is concluded that the rates of stress and strain posses the rδ-1 singularity near the tip crack, and the stresses remain finite at the crack tip.

Based on Zwick/Roell,this paper had carried on flexural experiments of epoxy resin filled with nano-silica particles, obtaining related mechanical properties.Microstructures of nanocomposites were analyzed by scanning electron microscopy (SEM) in the meanwhile. The flexural experiments revealed that nano- silica particles strengthened epoxy resin very well, and flexural modulus of modified matrices rised due to rigid silica particles, compared with pure epoxy matrices. Flexural strengths of epoxies modified by silica nanoparticles improved significantly.

We filled different proportions of inorganic packing(nano-silica) in the epoxy resin and investigated the flexural properties of modified epoxy resin compared with pure epoxy resin, based on the mechanics experiments using Zwick/Roell equipment. The experimental results showed the performance of modified epoxy resin by proper proportions of inorganic packing increased significantly compared with pure epoxy resin, but excessive inorganic packing had no help in improving the performance of epoxy resin and even cause some decline of the properties.

In the present paper, the mechanical model of dynamic propagation interface crack of the compression-shear mixed mode is proposed by using the elastic-viscoplastic constitutive model. Then the governing equations of propagation crack interface at crack tip are given. The numerical analysis is accomplished for the interface crack of compression-shear mixed mode by introducing a displacement potential function and some boundary conditions at interface crack tip. The distributed regularities of stress-strain fields of interface crack tip are discussed with several special parameters. The numerical results show that the viscosity effect is a main factor of interface propagating at crack-tip field, and the interface crack-tip is a viscoplastic field that is governed by viscosity coefficient、Mach number and singularity exponent.

The existence of viscosity effect at the interface of double dissimilar materials has an important impact to the distribution of interface crack-tip field and the properties variety of the interface itself. The singularity and viscosity are considered in crack-tip, and the elastic-viscoplastic governing equations of double dissimilar materials at interface crack-tip field are established. The displacement potential function and boundary condition of interface crack-tip are introduced, and the numerical analysis of elstic-viscoplastic/rigid interface for mode I are worked out. The stress-strain fields are obtained at the crack-tip and the variation rules of solutions are discussed according to each parameter. The numerical results show that the viscosity effect is a main factor of interface propagating at crack-tip field, and the interface crack-tip is a viscoplastic field that is governed by viscosity coefficient、Mach number and singularity exponent.

The existence of viscosity effect at the interface of double dissimilar materials has an important impact to the distribution of interface crack-tip field and the properties variety of the interface itself. The singular is considered in crack-tip, and the elastic-viscoplastic governing equations of double dissimilar materials at quasi-static propagating interface crack-tip field are established. The displacement potential function and boundary condition of interface crack-tip are introduced, and the numerical analysis of rigid-elastic viscoplastic interface for mode II are worked out. The stress-strain fields are obtained at the crack-tip and the variations of solutions are discussed according to each parameter. The numerical results show that the viscosity effect is a main factor of interface propagating crack-tip field, and the interface crack-tip is a viscoplastic field that is governed by viscosity coefficient、Mach number and singular factor.

The existence of viscosity effect at the interface of double dissimilar materials has an important impact on the distribution of the interface crack-tip field and the properties variety of the interface itself. The singularity and viscosity are considered in the crack-tip. The elastic-viscoplastic governing equations of double dissimilar materials at the interface crack-tip field are established. The displacement potential function and boundary condition of interface crack-tip are introduced. The numerical analysis of elastic-viscoplastic/rigid interface for mode III is worked out. The stress-strain fields are obtained at the crack-tip and the variation rules of solutions are discussed according to each parameter. The numerical results show that the viscosity effect is a main factor of the interface propagating in the crack-tip field, and the interface crack-tip is a viscoplastic field governed by the viscosity coefficient, Mach number (Ma), and singularity exponent.

In the present paper, the mechanical model of dynamic propagation interface crack of the compression-shear mixed mode is proposed by using the elastic-viscoplastic constitutive model. Then the governing equations of propagation crack interface at crack tip are given. The numerical analysis is accomplished for the interface crack of compression-shear mixed mode by introducing a displacement potential function and some boundary conditions at interface crack tip. The distributed regularities of stress-strain fields of interface crack tip are discussed with several special parameters. The numerical results show that the viscosity effect is a main factor of interface propagating at crack-tip field, and the interface crack-tip is a viscoplastic field that is governed by viscosity coefficient、Mach number and singularity exponent.

The viscosity of material is considered at propagating crack-tip. Under the assumption that the artificial viscosity coefficient is in inverse proportion to the power law of the plastic strain rate, an elastic-viscoplastic asymptotic analysis is carried out for moving crack-tip fields in power-hardening materials under plane-strain condition. A continuous solution is obtained containing no discontinuities. The variations of the numerical solution are discussed for mode I crack according to each parameter. It is shown that stress and strain both possess exponential singularity. The elasticity, plasticity and viscosity of material at the crack-tip only can be matched reasonably under linear-hardening condition. The tip field contains no elastic unloading zone for mode I crack.

Under the assumption that the artificial viscosity coefficient at the propagating crack tip is in inverse proportion to power law of the plastic strain rate, a rate-sensitive constitutive relationship is derived for perfect elastic-plastic material. With the adoption of the rate-sensitive constitutive relationship, it is asymptotically investigated the propagating tip fields of plane strain mode II. And the quasi-static equations are obtained separately governing the stress and strain fields at the crack-tip by means of Airy stress function. Numerical calculations of governing equations are carried out by double parameters shooting, with selections of appropriate values of each characteristic parameter by combinations of boundary, and the fully continuous stress-strain fields are obtained at the crack-tip. The analytical and computational results indicate that viscosity effect is an important factor in crack-tip fields.

Under the assumption that the artificial viscosity coefficient at the propagating crack tip is in inverse proportion to power law of the plastic strain rate, a rate-sensitive constitutive relationship is derived for perfect elastic-plastic material. With the adoption of the rate-sensitive constitutive relationship, it is asymptotically investigated the propagating tip fields of plane strain mode I. And the quasi-static equations are obtained separately governing the stress and strain fields at the crack-tip by means of Airy stress function. Numerical calculations of governing equations are carried out by double parameters shooting, with selections of appropriate values of each characteristic parameter by combinations of boundary, and the fully continuous stress-strain fields are obtained at the crack-tip. The analytical and computational results indicate that viscosity effect is an important factor in crack-tip fields.

An elastic-viscoplastic constitutive model was adopted to analyze asymptotically the tip-field of moving crack in linear-hardening materials under plane strain condition. Under the assumption that the artificial viscosity coefficient was in inverse proportion to power law of the rate of effective plastic strain, it is obtained that stress and strain both possess power law singularity and the singularity exponent is uniquely determined by the power law exponent of the rate of effective plastic strain. Variations of zoning structure according to each material parameter were discussed by means of numerical computation for the tip-field of mode II dynamic propagating crack, which show that the structure of crack tip field is dominated by hardening coefficient rather than viscosity coefficient. The secondary plastic zone can be ignored for weak hardening materials while the secondary plastic zone and the secondary elastic zone both have important influence on crack tip field for strong hardening materials. The dynamic solution approaches to the corresponding quasi-static solution when the crack moving speed goes to zero, and further approaches to the HR (Hui-Riedel) solution when the hardening coefficient is equal to zero.

Adopting an elastic-viscoplastic, the asymptotic problem of mode I propagating crack-tip field is investigated. Various asymptotic solutions resulting from the analysis of crack growing programs are presented. The analysis results show that the quasistatically growing crack solutions are the special case of the dynamic propagating solutions. Therefore these two asymptotic solutions can be unified.

The generation and release of algal toxin Microcystin-LR (MCLR), as well as the intracellular organic chemicals were studied during the inhibition processes of Microcystis aeruginosa using hydroquinone as the inhibitor. According to the dose-effect relationship, the corresponding dosages of EC20, EC50, EC70, EC90, EC99 were added to the algae suspension. The TOC was determined by the total organic carbon analyzer, and the three-dimensional fluorescence spectrum was obtained by the fluorescence spectrophotometer. The results showed that the generation of MCLR was inhibited at EC20 and the total MCLR was 72.4%-83.0% of the control samples. Whereas the cells were stimulated to produce higher amount of MCLR, and the total MCLR was 1.77-3.13 times as high as that of the control samples at EC50-EC99. The intracellular MCLR was largely released to the water at EC70-EC99. The release of other intracellular organic chemicals mainly referred to humic-like and fulvic-like substances, which were unstable and had an obvious degradation and transformation after 6 days of cultivation.

The paper studied the variation of algal activity during the electrochemical inactivation and the influence factors by the use of TTC-dehydrogenase activity and neutral red staining assays. The treatment reactor was consisted of Ti/RuO2 rod as anode and stainless steel pipe as cathode. The results showed that algal inactivation rate was 45% in cell density after 30 min treatment at 8 mA/cm2. Whereas the decrease of TTC-dehydrogenase activity was 94% and neutral red staining percentage was 100%. The algae after treatment was unable to regrow and it revealed that the algal activity assays can reflect the inactivation effect more correctly than cell density. The electrolytes could influence the inactivation efficiency. The electrolytes of Na2SO4 and NaNO3 had similar effects on algal inactivation and Na2SO4 concentration had small influence on the treatment. However, when the electrolyte contained 0.1 mmol/L NaCl, the algal inactivation was improved obviously with the 87% for TTC-dehydrogenase activity decrease and 82% for neutral red staining ratio. The initial algal concentration also influenced the treatment efficiency. If cell density increased, the inactivation efficiency decreased significantly. All algal cells in samples with cell density of 4.4 x 10(7) cells/L were completely inactivated by the use of natural water as electrolyte within 1 minute.

The paper studied the algal inactivation and removal by pulsed magnetic field with varying frequency. The results indicated that algae could be inactivated and killed by the magnetic treatment for the circulating water sample. When the accumulated resident time reached 6 minutes, the algae became to die with the mortality of 94%. If the resident time were 10 minutes, the algal mortality would be more than 96%. The treated algae didn't grow within 120 hours, which indicated that the "magnetic memory time" can reach 120 hours. For the static sample in magnetic field, the inhibition effect became to do the work after 1 hour. Different treatment methods brought about different results. It was more propitious to inactivate the algae for circulating sample.