The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with ...The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.展开更多
Transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joints can be classified into three distinct regions, i.e. the particulate segregation region, the denuded particulate region and the ...Transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joints can be classified into three distinct regions, i.e. the particulate segregation region, the denuded particulate region and the base material region. The microstructure of the particulate segregation region consists of alumina particulate and Al alloy matrix with the Al 2Cu and MgAl 2O 4. It contains more and smaller alumina particulates compared with the base material region. The TLP bonded joints have the tensile strength of 150 MPa ~200 MPa and the shear strength of 70 MPa ~100 MPa . With increasing tensile stress, cracks initiate in the particulate segregation region, especially in the particulate/particulate interface and the particulate/matrix interface, and propagate along particulate/matrix interface, througth thin matrix metal and by linking up the close cracks. The particulate segregation region is the weakest during tensile testing and shear testing due to obviously increased proportion of weak bonds (particulate particulate bond and particulate matrix bond).展开更多
Interactions between different components in α-starch based composite binder for green sand mould/core were investigated by using XRD, IR spectra, 1H NMR spectra and SEM. Several adhesive hardening structures and the...Interactions between different components in α-starch based composite binder for green sand mould/core were investigated by using XRD, IR spectra, 1H NMR spectra and SEM. Several adhesive hardening structures and theories of the binder at room temperature were proposed according to the interactions between various compositions. Thus, the reasons for the binder to have excellent combination properties and unique adhesive bonding and self-curing characteristics were explained by these theories successfully. And the theories are of great directive importance to design and development of composite binder for green sand mould/core.展开更多
The enhancement of interface bonding between cement and polymerand the structural reticula- tion of the water-soluble polymer areproposed to minimize the shortening of the mechanical properties ofmacro-de- fect-free(M...The enhancement of interface bonding between cement and polymerand the structural reticula- tion of the water-soluble polymer areproposed to minimize the shortening of the mechanical properties ofmacro-de- fect-free(MDF)cement based composites at high relativehumidity. The MDF composites incorporated with vari- ouscross-coupling agents studied experimentally. The results show thatthe MDF composites modified with small amounts of cross-couplingagent had raised mechanical properties, but it is more important thatthe modified MDF composites had a significant increase in waterresistance compared to the original one.展开更多
In spray atomization and codeposition, a molten stream of metal is disintegrated into a fine dispersion of droplets by high velocity gas jets. The resulting semi-solidified droplets are directed towards a substrate wh...In spray atomization and codeposition, a molten stream of metal is disintegrated into a fine dispersion of droplets by high velocity gas jets. The resulting semi-solidified droplets are directed towards a substrate where they impact and collect as rapidly solidified splats. Relatively high rates of solidification are achieved as a result of the thinness of the splats and the rapid heat extraction during flight and upon impacting with the substrate. The processing method uses codeposition of the metallic semi-solidified droplets (metallic matrix) with the injected reinforcement ceramic particles. In the present paper, the microstructures, mechanical properties, interfacial properties, thermal stability and aging behaviour of spray atomized and codeposited Al-Li-X MMC's (injected X=SiC, Al2O3) are reported and correlated to the processing conditions.展开更多
A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudina...A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudinal arrangement. Simulating electromagnetic responses of the structure, we verify that the structure exhibits the double Fano resonances, which originate from the coupling between magnetic quadrupoles and electric dipoles and the coupling between electric quadrupoles and electric dipoles. Simulation results also demonstrate that the structure is polarization-insensitive and shows an analogue of electromagnetically induced transparency at the two Fano resonances. Such a plasmonic structure has potential applications in photoelectric elements.展开更多
Magnesium powders were mechanically alloyed with SiO2 powder particles having different particle sizes using nigh-energy ball milling techniques under Ar atmosphere for 1 h. The powders were consolidated with cold pre...Magnesium powders were mechanically alloyed with SiO2 powder particles having different particle sizes using nigh-energy ball milling techniques under Ar atmosphere for 1 h. The powders were consolidated with cold pressing under 560 MPa. They were then sintered at 550℃ for 45 min under Ar atmosphere. The composites obtained on the Mg-SiO2 system were investigated using the Archimedes principle, a differential scanning calorimeter, X-ray diffraction, optic microscopy, and scanning electron microscopy. For the mechanically alloyed powders, the solid-state reaction of the synthesis of Mg2Si and MgO progressed further during sintering of the materials. The results showed that the strengthening mechanisms were dependent on dispersion hardening of fine Mg2Si and MgO particulates dispersed homogeneously in the matrix. Mg-展开更多
The longitudinal wave propagating in one-dimensional periodic piezoelectric composite rod with inter-coupling between different piezoelectric segments is investigated. The analytical formulae for such a structure are ...The longitudinal wave propagating in one-dimensional periodic piezoelectric composite rod with inter-coupling between different piezoelectric segments is investigated. The analytical formulae for such a structure are shown and the dispersion relation is calculated. The results show that, by introducing the inter-coupling between the different piezoelectric segments, which is accomplished by serially connecting every n piezoelectric segment into supercells, some tunable Bragg band gaps can accordingly be opened in the low frequency region. The investigation could provide a new guideline for the tunable phononic crystal under passive control.展开更多
The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coh...The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coherent feature. Its orientation relationship is (020)γ//(220)TiC, [001]γ||[001]TiC. During the aging at 1473 K, the TiC/γ interface may dissolve in matrix and lamellar M23C6 compound may precipitate from γ-matrix.展开更多
A new PVK-based photorefractive polymer composite sensitized by C60 and doped with a higher content of EO chromophore was prepared. The high optical quality thin-film was formed between two ITOcovered glass electrode...A new PVK-based photorefractive polymer composite sensitized by C60 and doped with a higher content of EO chromophore was prepared. The high optical quality thin-film was formed between two ITOcovered glass electrodes. Two-beam-coupling (2BC) experiment was performed by using a He-Ne laser (at wavelength 632.8nm), and an obvious photorefractive performance was observed. The dependence of two-beamcoupling gain coefficient on the applied poling dc electric field was measured.展开更多
1 Scope This standard specifies the definition, classification, technical requirements, test methods, inspection rules, packing, marking, transportation and quality certificate of corundum block containing plastic ph...1 Scope This standard specifies the definition, classification, technical requirements, test methods, inspection rules, packing, marking, transportation and quality certificate of corundum block containing plastic phase.展开更多
The booming development of DIW technology present an unprecedented prospect in energetic materials field and has attracted great interest due to its relative simplicity and high flexibility of manufacturing.Herein,a n...The booming development of DIW technology present an unprecedented prospect in energetic materials field and has attracted great interest due to its relative simplicity and high flexibility of manufacturing.Herein,a novel CL-20 based explosive ink formulation have been developed successfully for MEMS initiation systems via DIW technology.We designed PVA/GAP into an oil-in-water(O/W)emulsion,in the way that the aqueous solution of PVA as water phase,the ethyl acetate solution of GAP as oil phase,the combination of Tween 80 and SDS as emulsifier,BPS as a curing agent of GAP.The ideal formulation with good shear-thinning rheology properties and clear gel point was prepared using only 10 wt%emulsion.The dual-cured network formed during the curing process made the printed sample have good mechanical properties.The printed samples had satisfactory molding effect without cracks or fractures,the crystal form of CL-20 not changed and the thermal stability have improved.Deposition of explosive inks via DIW in micro-scale grooves had excellent detonation performances,which critical detonation size was 1×0.045 mm,detonation velocity was 7129 m/s and when the corner reaching 150°can still detonated stably.This study may open new avenues for developing binder systems in explosive ink formulations.展开更多
This paper presents the applications of digital image correlation technique to the mesoscopic damage and fracture study of some granular based composite materials including steel- fiber reinforced concrete,sandstone a...This paper presents the applications of digital image correlation technique to the mesoscopic damage and fracture study of some granular based composite materials including steel- fiber reinforced concrete,sandstone and crystal-polymer composite.The deformation fields of the composite materials resulted from stress localization were obtained by the correlation computation of the surface images with loading steps and thus the related damage prediction and fracture parameters were evaluated.The correlation searching could be performed either directly based on the gray levels of the digital images or from the wavelet transform(WT)coefficients of the transform spectrum.The latter was developed by the authors and showed higher resolution and sensitivity to the singularity detection. Because the displacement components came from the rough surfaces of the composite materials without any coats of gratings or fringes of optical interferometry,both surface profiles and the deformation fields of the composites were visualized which was helpful to compare each other to analyze the damage of those heterogeneous materials.展开更多
The flower-meristem-identity gene APETALA2(AP2), one of class-A genes, is involved in the establishment of the floral meristem and the forming of sepals and petals. Codon usage bias(CUB) identifies differences among s...The flower-meristem-identity gene APETALA2(AP2), one of class-A genes, is involved in the establishment of the floral meristem and the forming of sepals and petals. Codon usage bias(CUB) identifies differences among species, meanwhile dynamic analysis of base composition can identify the molecular mechanisms and evolutionary relationships of a specific gene. In this study, eight coding sequences(CDS) of AP2 gene were selected from different plant species using the Gen Bank database. Their nucleotide composition(GC content), genetic index, relative synonymous codon usage(RSCU) and relative codon usage bias(RCUB) were calculated with R Software to compare codon bias and base composition dynamics of AP2 gene codon usage patterns in different plant species. The results showed that the usage of AP2 gene codons from different plant species were influened by GC bias, especially GC3 s. Overall, base composition analysis indicated that the usage frequency of codon AT in the gene coding sequence was higher than GC among AP2 gene CDS from different plant species. Furthermore, most AP2 gene CDSs ended with AT; AGA, GCU and UGU had relatively high RSCU values as the most dominant codon; the usage characteristic of the AP2 gene codon in Malus domestica was similar to that of Vitis vinifera; Paeonia lactiflora was similar to Paeonia suffruticosa and Solanum lycopersicum was similar to Petunia×hybrida. There was a moderate preference in the usage of AP2 gene codon among different plant species from relatively low frequency of optimal codon(Fop) values and high effective number of codons(ENC) value. This study has revealed the usage characteristics of the AP2 gene codon from the comparision of AP2 gene codon preference and base dynamics in different plant species and provide a platform for further study towards transgenic engineering and codon optimization.展开更多
In this work,the microstructure,failure behavior and interfacial properties with respective to the interfacial domain in SiCf/BN/SiC and C_(f)/PyC/SiC composites were studied via the fiber push-in test.The differences...In this work,the microstructure,failure behavior and interfacial properties with respective to the interfacial domain in SiCf/BN/SiC and C_(f)/PyC/SiC composites were studied via the fiber push-in test.The differences in the mechanical response of the interfacial domain were observed.During the fiber push-in test for SiCf/BN/SiC,the interface debonding accompanied with interphase fracture occurred,resulting in an obvious sign of the onset of debonding on loading-displacement(P-u)curves.While the good continuity of P-u curves can be observed for Cf/PyC/SiC,which is due to that the failure is in the form of interface debonding along with interphase lateral slipping caused by the extension of buckled carbon fiber,without any interphase fracture.The interfacial properties calculated from the fiber push-in test show that Cf/PyC/SiC possesses a weaker interfacial domain compared with SiC_(f)/BN/SiC.The interfacial shear stress of SiCf/BN/SiC and C_(f)/PyC/SiC composites amounts 94.2 and 48.1 MPa,respectively.展开更多
A surrogate based particle swarm optimization (SBPSO) algorithm which combines the surrogate modeling technique and particle swarm optimization is applied to the reliability- based robust design (RBRD) of composit...A surrogate based particle swarm optimization (SBPSO) algorithm which combines the surrogate modeling technique and particle swarm optimization is applied to the reliability- based robust design (RBRD) of composite pressure vessels. The algorithm and efficiency of SBPSO are displayed through numerical examples. A model for filament-wound composite pressure vessels with metallic liner is then studied by netting analysis and its responses are analyzed by using Finite element method (performed by software ANSYS). An optimization problem for maximizing the performance factor is formulated by choosing the winding orientation of the helical plies in the cylindrical portion, the thickness of metal liner and the drop off region size as the design variables. Strength constraints for composite layers and the metal liner are constructed by using Tsai-Wu failure criterion and Mises failure criterion respectively. Numerical examples show that the method proposed can effectively solve the RBRD problem, and the optimal results of the proposed model can satisfy certain reliability requirement and have the robustness to the fluctuation of design variables.展开更多
The animal experiment of viscose carbon fiber based C/C composites applied in bone defection intramedullary fixation was carried out in New Zealand white rabbits.The histological observation on the 100th day after sur...The animal experiment of viscose carbon fiber based C/C composites applied in bone defection intramedullary fixation was carried out in New Zealand white rabbits.The histological observation on the 100th day after surgical operation indicated that the experimental animals recovered well and the bone defect area was reconstructed by new bone trabecula.Immunohistochemical observation of leukocyte common antigen and macrophage suggested that intramedullary fixation materials did not induct any chronic toxicity reactions such as inflammatory reactions,macrophage reactions and formation of granulation tissue.The tissue compatibility of this material was excellent.Meanwhile,the impurity element species and the biological toxic element content of viscose fiber based C/C composites were determined by atomic fluorescence analyzer and inductively coupled plasma atomic emission spectrometry.The results reveal that there are few biological toxic elements in the viscose fiber based C/C composites and it can satisfy the constituent demands of surgical implants.展开更多
The codon usage bias and the base compositions in the available 49 complete fish rhabdovirus genome sequences were investigated. The high correlation between GC12% and GC3% suggested that mutational pressure rather th...The codon usage bias and the base compositions in the available 49 complete fish rhabdovirus genome sequences were investigated. The high correlation between GC12% and GC3% suggested that mutational pressure rather than natural selection was the main factor determining the codon usage and base component in fish rhabdovirns, most of the spots lying below the expected curve ( ENC vs GC3% ) also suggested that codon usage bias in these 49 genomes was influenced by mutational pressure in codon usage pattern. Through PCA analysis based on RSCU, all ORFs in the 49 fish rhabdoviurs genomes were clustered into two parts, and this result showed that hosts played a role in codon usage pattern of fish rhabdovirns genomes. Further, comparison between SVCV, INHV, VHSV and their hosts suggested the effect of natural host on the codon usage pattern took part in the evolution process of fish rhabdovirns. This study represents the most comprehensive analysis to date for fish rhabdovirus eodon usage patterns.展开更多
文摘The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.
文摘Transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joints can be classified into three distinct regions, i.e. the particulate segregation region, the denuded particulate region and the base material region. The microstructure of the particulate segregation region consists of alumina particulate and Al alloy matrix with the Al 2Cu and MgAl 2O 4. It contains more and smaller alumina particulates compared with the base material region. The TLP bonded joints have the tensile strength of 150 MPa ~200 MPa and the shear strength of 70 MPa ~100 MPa . With increasing tensile stress, cracks initiate in the particulate segregation region, especially in the particulate/particulate interface and the particulate/matrix interface, and propagate along particulate/matrix interface, througth thin matrix metal and by linking up the close cracks. The particulate segregation region is the weakest during tensile testing and shear testing due to obviously increased proportion of weak bonds (particulate particulate bond and particulate matrix bond).
基金This work was supported by the China Postdoctoral Science Foundation(China Fund[1998]6)that was entitled“Synthesis of Modified Starch Binder and Its Application in Foundry”.Authors would like to thank academician Jinzong YANG and lecturer Hua ZHANG for the kind analyses and discussions.
文摘Interactions between different components in α-starch based composite binder for green sand mould/core were investigated by using XRD, IR spectra, 1H NMR spectra and SEM. Several adhesive hardening structures and theories of the binder at room temperature were proposed according to the interactions between various compositions. Thus, the reasons for the binder to have excellent combination properties and unique adhesive bonding and self-curing characteristics were explained by these theories successfully. And the theories are of great directive importance to design and development of composite binder for green sand mould/core.
文摘The enhancement of interface bonding between cement and polymerand the structural reticula- tion of the water-soluble polymer areproposed to minimize the shortening of the mechanical properties ofmacro-de- fect-free(MDF)cement based composites at high relativehumidity. The MDF composites incorporated with vari- ouscross-coupling agents studied experimentally. The results show thatthe MDF composites modified with small amounts of cross-couplingagent had raised mechanical properties, but it is more important thatthe modified MDF composites had a significant increase in waterresistance compared to the original one.
文摘In spray atomization and codeposition, a molten stream of metal is disintegrated into a fine dispersion of droplets by high velocity gas jets. The resulting semi-solidified droplets are directed towards a substrate where they impact and collect as rapidly solidified splats. Relatively high rates of solidification are achieved as a result of the thinness of the splats and the rapid heat extraction during flight and upon impacting with the substrate. The processing method uses codeposition of the metallic semi-solidified droplets (metallic matrix) with the injected reinforcement ceramic particles. In the present paper, the microstructures, mechanical properties, interfacial properties, thermal stability and aging behaviour of spray atomized and codeposited Al-Li-X MMC's (injected X=SiC, Al2O3) are reported and correlated to the processing conditions.
基金Supported by the National Innovative Projects for College Students under Grant No 201310320025the National Natural Science Foundation of China under Grant Nos 61401182 and 61372057the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudinal arrangement. Simulating electromagnetic responses of the structure, we verify that the structure exhibits the double Fano resonances, which originate from the coupling between magnetic quadrupoles and electric dipoles and the coupling between electric quadrupoles and electric dipoles. Simulation results also demonstrate that the structure is polarization-insensitive and shows an analogue of electromagnetically induced transparency at the two Fano resonances. Such a plasmonic structure has potential applications in photoelectric elements.
文摘Magnesium powders were mechanically alloyed with SiO2 powder particles having different particle sizes using nigh-energy ball milling techniques under Ar atmosphere for 1 h. The powders were consolidated with cold pressing under 560 MPa. They were then sintered at 550℃ for 45 min under Ar atmosphere. The composites obtained on the Mg-SiO2 system were investigated using the Archimedes principle, a differential scanning calorimeter, X-ray diffraction, optic microscopy, and scanning electron microscopy. For the mechanically alloyed powders, the solid-state reaction of the synthesis of Mg2Si and MgO progressed further during sintering of the materials. The results showed that the strengthening mechanisms were dependent on dispersion hardening of fine Mg2Si and MgO particulates dispersed homogeneously in the matrix. Mg-
基金Supported by the National Natural Science Foundation of China under Grant No 11274121
文摘The longitudinal wave propagating in one-dimensional periodic piezoelectric composite rod with inter-coupling between different piezoelectric segments is investigated. The analytical formulae for such a structure are shown and the dispersion relation is calculated. The results show that, by introducing the inter-coupling between the different piezoelectric segments, which is accomplished by serially connecting every n piezoelectric segment into supercells, some tunable Bragg band gaps can accordingly be opened in the low frequency region. The investigation could provide a new guideline for the tunable phononic crystal under passive control.
文摘The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coherent feature. Its orientation relationship is (020)γ//(220)TiC, [001]γ||[001]TiC. During the aging at 1473 K, the TiC/γ interface may dissolve in matrix and lamellar M23C6 compound may precipitate from γ-matrix.
文摘A new PVK-based photorefractive polymer composite sensitized by C60 and doped with a higher content of EO chromophore was prepared. The high optical quality thin-film was formed between two ITOcovered glass electrodes. Two-beam-coupling (2BC) experiment was performed by using a He-Ne laser (at wavelength 632.8nm), and an obvious photorefractive performance was observed. The dependence of two-beamcoupling gain coefficient on the applied poling dc electric field was measured.
文摘1 Scope This standard specifies the definition, classification, technical requirements, test methods, inspection rules, packing, marking, transportation and quality certificate of corundum block containing plastic phase.
基金This work was supported by the Graduate Education Innovation Project of Shanxi Province(2020SY401)No.55 Research Institute of China North Industries Group Corporation Open Innovation Fund(WDZC2020JJ017).
文摘The booming development of DIW technology present an unprecedented prospect in energetic materials field and has attracted great interest due to its relative simplicity and high flexibility of manufacturing.Herein,a novel CL-20 based explosive ink formulation have been developed successfully for MEMS initiation systems via DIW technology.We designed PVA/GAP into an oil-in-water(O/W)emulsion,in the way that the aqueous solution of PVA as water phase,the ethyl acetate solution of GAP as oil phase,the combination of Tween 80 and SDS as emulsifier,BPS as a curing agent of GAP.The ideal formulation with good shear-thinning rheology properties and clear gel point was prepared using only 10 wt%emulsion.The dual-cured network formed during the curing process made the printed sample have good mechanical properties.The printed samples had satisfactory molding effect without cracks or fractures,the crystal form of CL-20 not changed and the thermal stability have improved.Deposition of explosive inks via DIW in micro-scale grooves had excellent detonation performances,which critical detonation size was 1×0.045 mm,detonation velocity was 7129 m/s and when the corner reaching 150°can still detonated stably.This study may open new avenues for developing binder systems in explosive ink formulations.
基金The project supported by the National Natural Science Foundation of China (10125211 and 10072002),the Scientific Committee of Yunnan Province for the Program of Steel Fiber Reinforced Concrete,and the Institute of Chemical Materials,CAEP at Mianyang
文摘This paper presents the applications of digital image correlation technique to the mesoscopic damage and fracture study of some granular based composite materials including steel- fiber reinforced concrete,sandstone and crystal-polymer composite.The deformation fields of the composite materials resulted from stress localization were obtained by the correlation computation of the surface images with loading steps and thus the related damage prediction and fracture parameters were evaluated.The correlation searching could be performed either directly based on the gray levels of the digital images or from the wavelet transform(WT)coefficients of the transform spectrum.The latter was developed by the authors and showed higher resolution and sensitivity to the singularity detection. Because the displacement components came from the rough surfaces of the composite materials without any coats of gratings or fringes of optical interferometry,both surface profiles and the deformation fields of the composites were visualized which was helpful to compare each other to analyze the damage of those heterogeneous materials.
基金supported by the National Natural Science Foundation of China(31372097)the Agricultural Science&Technology Independent Innovation Fund of Jiangsu Province,China(CX(13)2014)
文摘The flower-meristem-identity gene APETALA2(AP2), one of class-A genes, is involved in the establishment of the floral meristem and the forming of sepals and petals. Codon usage bias(CUB) identifies differences among species, meanwhile dynamic analysis of base composition can identify the molecular mechanisms and evolutionary relationships of a specific gene. In this study, eight coding sequences(CDS) of AP2 gene were selected from different plant species using the Gen Bank database. Their nucleotide composition(GC content), genetic index, relative synonymous codon usage(RSCU) and relative codon usage bias(RCUB) were calculated with R Software to compare codon bias and base composition dynamics of AP2 gene codon usage patterns in different plant species. The results showed that the usage of AP2 gene codons from different plant species were influened by GC bias, especially GC3 s. Overall, base composition analysis indicated that the usage frequency of codon AT in the gene coding sequence was higher than GC among AP2 gene CDS from different plant species. Furthermore, most AP2 gene CDSs ended with AT; AGA, GCU and UGU had relatively high RSCU values as the most dominant codon; the usage characteristic of the AP2 gene codon in Malus domestica was similar to that of Vitis vinifera; Paeonia lactiflora was similar to Paeonia suffruticosa and Solanum lycopersicum was similar to Petunia×hybrida. There was a moderate preference in the usage of AP2 gene codon among different plant species from relatively low frequency of optimal codon(Fop) values and high effective number of codons(ENC) value. This study has revealed the usage characteristics of the AP2 gene codon from the comparision of AP2 gene codon preference and base dynamics in different plant species and provide a platform for further study towards transgenic engineering and codon optimization.
基金the support of IMDEA Materials Institute of Spainsupported by the National Natural Science Foundation of China(Project Nos.52072303 and 51821091)。
文摘In this work,the microstructure,failure behavior and interfacial properties with respective to the interfacial domain in SiCf/BN/SiC and C_(f)/PyC/SiC composites were studied via the fiber push-in test.The differences in the mechanical response of the interfacial domain were observed.During the fiber push-in test for SiCf/BN/SiC,the interface debonding accompanied with interphase fracture occurred,resulting in an obvious sign of the onset of debonding on loading-displacement(P-u)curves.While the good continuity of P-u curves can be observed for Cf/PyC/SiC,which is due to that the failure is in the form of interface debonding along with interphase lateral slipping caused by the extension of buckled carbon fiber,without any interphase fracture.The interfacial properties calculated from the fiber push-in test show that Cf/PyC/SiC possesses a weaker interfacial domain compared with SiC_(f)/BN/SiC.The interfacial shear stress of SiCf/BN/SiC and C_(f)/PyC/SiC composites amounts 94.2 and 48.1 MPa,respectively.
基金supported by the Natural Science Foundation of China(No.10772070)National Basic Research Program of China(No.2011CB013800)
文摘A surrogate based particle swarm optimization (SBPSO) algorithm which combines the surrogate modeling technique and particle swarm optimization is applied to the reliability- based robust design (RBRD) of composite pressure vessels. The algorithm and efficiency of SBPSO are displayed through numerical examples. A model for filament-wound composite pressure vessels with metallic liner is then studied by netting analysis and its responses are analyzed by using Finite element method (performed by software ANSYS). An optimization problem for maximizing the performance factor is formulated by choosing the winding orientation of the helical plies in the cylindrical portion, the thickness of metal liner and the drop off region size as the design variables. Strength constraints for composite layers and the metal liner are constructed by using Tsai-Wu failure criterion and Mises failure criterion respectively. Numerical examples show that the method proposed can effectively solve the RBRD problem, and the optimal results of the proposed model can satisfy certain reliability requirement and have the robustness to the fluctuation of design variables.
基金the Fundamental Research Funds for the Central Universities of China(No.11CX04033A)the Postdoctoral Innovation Projection of Shandong Province(No.201103085)
文摘The animal experiment of viscose carbon fiber based C/C composites applied in bone defection intramedullary fixation was carried out in New Zealand white rabbits.The histological observation on the 100th day after surgical operation indicated that the experimental animals recovered well and the bone defect area was reconstructed by new bone trabecula.Immunohistochemical observation of leukocyte common antigen and macrophage suggested that intramedullary fixation materials did not induct any chronic toxicity reactions such as inflammatory reactions,macrophage reactions and formation of granulation tissue.The tissue compatibility of this material was excellent.Meanwhile,the impurity element species and the biological toxic element content of viscose fiber based C/C composites were determined by atomic fluorescence analyzer and inductively coupled plasma atomic emission spectrometry.The results reveal that there are few biological toxic elements in the viscose fiber based C/C composites and it can satisfy the constituent demands of surgical implants.
基金Supported by National Natural Science Foundation of China(No.31402347)Guangdong Special Marine Fishery Science and Technology Project(A201701C04)+3 种基金"Molecular epidemiological study of Cy HV-3 in Guangdong Province",2016 Guangdong Special Funds for Fish DiseasesGuangzhou Science and Technology Plan Projects(201707010216)Guangdong Science and Technology Plan Projects(2017A020224019)Guangdong Science and Technology Plan Projects(2016A020210029)
文摘The codon usage bias and the base compositions in the available 49 complete fish rhabdovirus genome sequences were investigated. The high correlation between GC12% and GC3% suggested that mutational pressure rather than natural selection was the main factor determining the codon usage and base component in fish rhabdovirns, most of the spots lying below the expected curve ( ENC vs GC3% ) also suggested that codon usage bias in these 49 genomes was influenced by mutational pressure in codon usage pattern. Through PCA analysis based on RSCU, all ORFs in the 49 fish rhabdoviurs genomes were clustered into two parts, and this result showed that hosts played a role in codon usage pattern of fish rhabdovirns genomes. Further, comparison between SVCV, INHV, VHSV and their hosts suggested the effect of natural host on the codon usage pattern took part in the evolution process of fish rhabdovirns. This study represents the most comprehensive analysis to date for fish rhabdovirus eodon usage patterns.