A study was conducted to evaluate the current production capabilities of the Mark One? 3D printer in printing carbon fibre reinforced thermoplastic (CFRTP) tensile test specimens according to the JIS K 7073 by making ...A study was conducted to evaluate the current production capabilities of the Mark One? 3D printer in printing carbon fibre reinforced thermoplastic (CFRTP) tensile test specimens according to the JIS K 7073 by making use of fused deposition modelling. Several different types of CFRTP tensile test specimens are printed and are tensile tested in the longitudinal direction to obtain an overview of the mechanical properties of 3D printed CFRTP material. These properties are compared with the literature values known for composite materials to see if these agree. The main goal of this research is to increase the knowledge of the 3D printing process of CFRTP and to later use this knowledge to further improve the 3D printing process to obtain stronger 3D printed CFRTP materials.展开更多
This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recen...This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve e a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in ongoing developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.展开更多
In this overall survey of the seagrasses of China 15 species are listed, eight of which are recorded for the first time. The Potamogetonaceae (subfamilies Zosteroideae and Cymodoceoideae) are represented by 10 species...In this overall survey of the seagrasses of China 15 species are listed, eight of which are recorded for the first time. The Potamogetonaceae (subfamilies Zosteroideae and Cymodoceoideae) are represented by 10 species, and the Hydrocharitaceae (subfamilies Vallisnerioideae, Thalassioideae and Halophiloideae)by 5 species. Halophila ovalis (R.Br.) Hook, f. is represented by 2 subspecies. A key to the species based on vegetative and generative characteristics is presented.展开更多
Although neurophysiological and psychophysical proof of osseoperception is accumulating, histomorphometric evidence for the neural mechanisms of functional compensation following immediate and delayed implant loading ...Although neurophysiological and psychophysical proof of osseoperception is accumulating, histomorphometric evidence for the neural mechanisms of functional compensation following immediate and delayed implant loading is still lacking. For this randomized split-mouth study, six mongrel dogs randomly received one of four treatment protocols at 36 implant-recipient sites over 16 weeks （third maxillary incisor, third and fourth mandibular premolar）： immediate implant placement and immediate loading （liP＋ IL）; delayed implant placement and delayed loading （DIP＋DL）; delayed implant placement and immediate loading （DIP＋IL）; and natural extraction socket healing （control）. Histomorphometry was performed in the peri-implant bone and soft tissues within 300 pm around the implants. Immunocytochemistry and transmission electron microscopy were used to confirm the presence of neural structures and to reveal their ultrastructural characteristics, respectively. Myelinated nerve fibres densely populated the peri-implant crestal gingival and apical regions, although they were also identified in the woven bone and in the osteons near the implant threads. Compared with the control group in the mandible, the group that received IIP＋IL showed a higher innervation （in N.mm^-2, 5.94±1.12 vs. 3.15±0.63, P〈0.001） and smaller fibre diameter （in pm, 1.37±0.05 vs. 1.64±0.13, P=0.016）, smaller axon diameter （in pm, 0.89±0.05 vs. 1.24±0,10, P=0.009） and g-ratio （0.64±0.04 vs. 0.76±0.05, P〈0.001） in the middle region around the implants. Compared with DIP＋IL in the mandible, IIP＋IL had a higher nerve density （in N.mm^-2, 13.23±2.54 vs. 9.64±1.86, P=0.027）, greater fibre diameter （in pm, 1.32±0.02 vs. 1.20±0.04, P=0.021）, greater axon diameter （in μm, 0.92±0.01 vs. 0.89±0.03, P=-0.035） and lower g-ratio （0.69±0.01 vs. 0.74±0.01, P=-0.033） in the apical region around the implants. It may be assumed that the treatment protocol with liP＋ IL is the preferred me展开更多
This article presents development of a novel self-healing technology for asphalt pave- ments, where asphalt binder rejuvenator is encapsulated within the compartmented alginate fibres. The key objective of the study w...This article presents development of a novel self-healing technology for asphalt pave- ments, where asphalt binder rejuvenator is encapsulated within the compartmented alginate fibres. The key objective of the study was to optimise the compartmented alginate fibre design, i.e., maximising amount of rejuvenator encapsulated within the fibre. The results demonstrate that optimum rejuvenator content in the alginate fibre is of 70：B0 rejuvenator/alginate ratio. The fibres are of sufficient thermal and mechanical strength to survive harsh asphalt mixing and compaction processes. Furthermore, results illustrate that zeer open asfalt beton （ZOAB） asphalt mix containing 5% of 70：30 rejuvenator/alginate ratio compartmented alginate fibres has higher strength, stiffness and better healing properties in comparison to the control asphalt mix, i.e., mix without fibres, and mix containing fibres with lower rejuvenator content. These results show that compartmented alginate fibres encapsulating bitumen rejuvenator present a promising new approach for the development of self-healing asphalt pavement systems.展开更多
The efficiency of activated biochar fibres obtained from Opuntia Ficus lndica regarding me sorpuon oi trlvalent samarium （Sm（Ⅲ）） from aqueous solutions was investigated by batch experiments. The effect of various...The efficiency of activated biochar fibres obtained from Opuntia Ficus lndica regarding me sorpuon oi trlvalent samarium （Sm（Ⅲ）） from aqueous solutions was investigated by batch experiments. The effect of various physicochemical parameters （e.g. pH, initial metal concentration, ionic strength, temperature and contact time） on the Sm（III） adsorption was studied and the surface species were characterized by FTIR spectroscopy prior to and after the lanthanide sorption. The experimental results showed that the acti- vated biochar fibres possessed extraordinary sorption capacity for Sm（Ⅲ） in acidic solutions （qmax=90 g/kg, pH 3.0） and near neutral solutions （qmax=350 g/kg, pH 6.5）, This was attributed to the formation of samarium complexes with the surface carboxylic moieties, available in high density on the lamellar structures of the bio-sorbent.展开更多
Low velocity impact experiments were carried out on E-glass/epoxy composite laminates having varying thicknesses at sub zero and elevated temperatures using hemi spherical steel impactor of 16 mm diameter with impact ...Low velocity impact experiments were carried out on E-glass/epoxy composite laminates having varying thicknesses at sub zero and elevated temperatures using hemi spherical steel impactor of 16 mm diameter with impact energies in the rage of 50-150 J.The performance of the laminates was assessed in terms of energy absorption,maximum displacement,peak force and failure behaviour.Results indicated that the effect of temperature on energy absorption of the laminate is negligible although the laminates are embrittling at sub zero temperatures.However it has influence on failure behaviour and displacement.Peak force has increased linearly with increase in laminate thickness from 5 to 10 mm.However it got reduced by 25% when temperature was increased from-20℃ to 100℃,Based on experimental results,laminate perforation energies were predicted using curve fitting equations.Statistical analysis was carried out using Taguchi method to identify the global effects of various parameters on laminate performance and confirmed that the laminate thickness has significant influence as compared to temperature,for the studied range.展开更多
The present study focuses on the formulation of new composite consisting of plaster and raffia vinifera particle (RVP) with the purpose to reducing energy consumption. The aim of this study is to test this new compoun...The present study focuses on the formulation of new composite consisting of plaster and raffia vinifera particle (RVP) with the purpose to reducing energy consumption. The aim of this study is to test this new compound as an insulating eco-material in building in a tropical climate. The composites samples were developed by mixing plaster with raffia vinifera particles (RVP) using three different sizes (1.6 mm, 2.5 mm and 4 mm). The effects of four different RVP incorporations rates (i.e., 0wt%, 5wt%;10wt%;15wt%) on physical, thermal, mechanicals properties of the composites were investigated. In addition, the use of the raffia vinifera particles and plaster based composite material as building envelopes thermal insulation material is studied by the habitable cell thermal behavior instrumentation. The results indicate that the incorporation of raffia vinifera particle leads to improve the new composite physical, mechanical and thermal properties. And the parametric analysis reveals that the sampling rate and the size of raffia vinifera particles are the most decisive factor to impact these properties, and to decreases in the thermal conductivity which leads to an improvement to the thermal resistance and energy savings. The best improvement of plaster composite was obtained at the raffia vinifera particles size between 2.5 and 4.0 mm loading of 5wt% (C95P5R) with a good ratio of thermo-physical-mechanical properties. Additionally, the habitable cell experimental thermal behavior, with the new raffia vinifera particles and plaster-based composite as thermal insulating material for building walls, gives an average damping of 4°C and 5.8°C in the insulated house interior environment respectively for cold and hot cases compared to the outside environment and the uninsulated house interior environment. The current study highlights that this mixture gives the new composite thermal insulation properties applicable in the eco-construction of habitats in tropical environments.展开更多
Kenaf (Hibiscus cannabinus L) consists of various beneficial components like stalks, seeds, leaves, fibers, oils, proteins, allelopathic chemicals, and fiber strands, among other things. Despite the numerous uses of t...Kenaf (Hibiscus cannabinus L) consists of various beneficial components like stalks, seeds, leaves, fibers, oils, proteins, allelopathic chemicals, and fiber strands, among other things. Despite the numerous uses of the crop, there is little or no information on optimum agronomic practices such as planting date and N fertilization of the crop in the Upper East Region (UER) of Ghana where the crop is widely cultivated by smallholder farmers. Field experiments were therefore carried out in 2020 and repeated during the 2021 cropping season in the study area. The objective of the study was to determine appropriate planting date and N fertilization for increased kenaf productivity. In each year, the treatments consisted of 3 × 5 factorial combinations of three planting dates (1<sup>st</sup> July, 7<sup>th</sup> July and 14<sup>th</sup> July) and five levels of N (0, 20, 40, 60 and 80 kg/ha) replicated three times. The design of the experiment was a split-plot with the N fertilizer as the main plot and the planting date assigned to sub plot. The results showed that, planting kenaf in early (1<sup>st</sup>) July or N fertilization at the rate of 60 kg/ha increased plant density, stem height, stem diameter, dry bast and core yields in both cropping seasons.展开更多
Dynamic image analysis provides an automated evaluation method to determine the size and shape of multiple particles. This method represents a common application for ordinary bulk material. The latest draft of ISO 13...Dynamic image analysis provides an automated evaluation method to determine the size and shape of multiple particles. This method represents a common application for ordinary bulk material. The latest draft of ISO 13322–2:2021 describes the state of the art, but lacks instructions for handling fibrous bulk material. Interlocking fibres complicate the measurement conditions and require a disentanglement of fibrous samples during a pre-dispersion step. A further error source includes the fibre orientation inside the measurement zone of the device. If the thresholding algorithm fails to differentiate between the fibre projection area and the background, a subsequent image optimisation solves the problem. This article addresses the mentioned problems by analysing cotton cellulose and polyacrylonitrile fibres. Besides the execution of a pre-dispersion step, the experiments compare the discrepancies between dry and wet dispersion. Here, the software packages PAQXOS and ImageJ perform the image evaluation. In this case, the wet dispersion setup with a subsequent image evaluation by ImageJ provides comprehensible results.展开更多
The growing environmental concerns have led to attention on bio-based composite materials, such as the natural fibres, recycled carbon fibres and bio-based resins. Herein, the bio-based epoxy composites were reinforce...The growing environmental concerns have led to attention on bio-based composite materials, such as the natural fibres, recycled carbon fibres and bio-based resins. Herein, the bio-based epoxy composites were reinforced with ramie fibre (RF) and recycled carbon fibre (rCF) via inter-layer hybridisation. The dynamic mechanical analysis, tensile, flexural and impact properties characterisation were conducted to analyse the mechanical behaviour of the specimens. Also, the morphology of fractured surface after mechanical tests was studied under a scanning electron microscope. When the volume ratio between RF and rCF was varied from 100/0 to 0/100, the flexural and tensile strength of composites was significantly increased, while the impact strength was reduced. Thus the maximum values of flexural strength (182 MPa) and tensile strength (165 MPa) were observed for rCF reinforced composite, whilst impact strength of 24 kJ/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> was found for RF reinforced composite. Furthermore, the values of storage and loss modulus were increased with the rCF incorporation due to a greater degree of restriction with the addition of rCF into the matrix. The hybridisation was able to combine the specific properties of RF and rCF and optimise the mechanical performance of composites. Therefore, the alternative low-cost green composites are prepared which can replace synthetic materials for semi-structural applications.展开更多
文摘A study was conducted to evaluate the current production capabilities of the Mark One? 3D printer in printing carbon fibre reinforced thermoplastic (CFRTP) tensile test specimens according to the JIS K 7073 by making use of fused deposition modelling. Several different types of CFRTP tensile test specimens are printed and are tensile tested in the longitudinal direction to obtain an overview of the mechanical properties of 3D printed CFRTP material. These properties are compared with the literature values known for composite materials to see if these agree. The main goal of this research is to increase the knowledge of the 3D printing process of CFRTP and to later use this knowledge to further improve the 3D printing process to obtain stronger 3D printed CFRTP materials.
文摘This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve e a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in ongoing developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.
文摘In this overall survey of the seagrasses of China 15 species are listed, eight of which are recorded for the first time. The Potamogetonaceae (subfamilies Zosteroideae and Cymodoceoideae) are represented by 10 species, and the Hydrocharitaceae (subfamilies Vallisnerioideae, Thalassioideae and Halophiloideae)by 5 species. Halophila ovalis (R.Br.) Hook, f. is represented by 2 subspecies. A key to the species based on vegetative and generative characteristics is presented.
基金supported by the Natural Science Foundation of China (81000459)the Chinese Scholarship Council
文摘Although neurophysiological and psychophysical proof of osseoperception is accumulating, histomorphometric evidence for the neural mechanisms of functional compensation following immediate and delayed implant loading is still lacking. For this randomized split-mouth study, six mongrel dogs randomly received one of four treatment protocols at 36 implant-recipient sites over 16 weeks （third maxillary incisor, third and fourth mandibular premolar）： immediate implant placement and immediate loading （liP＋ IL）; delayed implant placement and delayed loading （DIP＋DL）; delayed implant placement and immediate loading （DIP＋IL）; and natural extraction socket healing （control）. Histomorphometry was performed in the peri-implant bone and soft tissues within 300 pm around the implants. Immunocytochemistry and transmission electron microscopy were used to confirm the presence of neural structures and to reveal their ultrastructural characteristics, respectively. Myelinated nerve fibres densely populated the peri-implant crestal gingival and apical regions, although they were also identified in the woven bone and in the osteons near the implant threads. Compared with the control group in the mandible, the group that received IIP＋IL showed a higher innervation （in N.mm^-2, 5.94±1.12 vs. 3.15±0.63, P〈0.001） and smaller fibre diameter （in pm, 1.37±0.05 vs. 1.64±0.13, P=0.016）, smaller axon diameter （in pm, 0.89±0.05 vs. 1.24±0,10, P=0.009） and g-ratio （0.64±0.04 vs. 0.76±0.05, P〈0.001） in the middle region around the implants. Compared with DIP＋IL in the mandible, IIP＋IL had a higher nerve density （in N.mm^-2, 13.23±2.54 vs. 9.64±1.86, P=0.027）, greater fibre diameter （in pm, 1.32±0.02 vs. 1.20±0.04, P=0.021）, greater axon diameter （in μm, 0.92±0.01 vs. 0.89±0.03, P=-0.035） and lower g-ratio （0.69±0.01 vs. 0.74±0.01, P=-0.033） in the apical region around the implants. It may be assumed that the treatment protocol with liP＋ IL is the preferred me
基金the Marie Curie IEF research funding, research project Self-healing Asphalt for Road Pavements (SHARP) (project number 622863)
文摘This article presents development of a novel self-healing technology for asphalt pave- ments, where asphalt binder rejuvenator is encapsulated within the compartmented alginate fibres. The key objective of the study was to optimise the compartmented alginate fibre design, i.e., maximising amount of rejuvenator encapsulated within the fibre. The results demonstrate that optimum rejuvenator content in the alginate fibre is of 70：B0 rejuvenator/alginate ratio. The fibres are of sufficient thermal and mechanical strength to survive harsh asphalt mixing and compaction processes. Furthermore, results illustrate that zeer open asfalt beton （ZOAB） asphalt mix containing 5% of 70：30 rejuvenator/alginate ratio compartmented alginate fibres has higher strength, stiffness and better healing properties in comparison to the control asphalt mix, i.e., mix without fibres, and mix containing fibres with lower rejuvenator content. These results show that compartmented alginate fibres encapsulating bitumen rejuvenator present a promising new approach for the development of self-healing asphalt pavement systems.
文摘The efficiency of activated biochar fibres obtained from Opuntia Ficus lndica regarding me sorpuon oi trlvalent samarium （Sm（Ⅲ）） from aqueous solutions was investigated by batch experiments. The effect of various physicochemical parameters （e.g. pH, initial metal concentration, ionic strength, temperature and contact time） on the Sm（III） adsorption was studied and the surface species were characterized by FTIR spectroscopy prior to and after the lanthanide sorption. The experimental results showed that the acti- vated biochar fibres possessed extraordinary sorption capacity for Sm（Ⅲ） in acidic solutions （qmax=90 g/kg, pH 3.0） and near neutral solutions （qmax=350 g/kg, pH 6.5）, This was attributed to the formation of samarium complexes with the surface carboxylic moieties, available in high density on the lamellar structures of the bio-sorbent.
文摘Low velocity impact experiments were carried out on E-glass/epoxy composite laminates having varying thicknesses at sub zero and elevated temperatures using hemi spherical steel impactor of 16 mm diameter with impact energies in the rage of 50-150 J.The performance of the laminates was assessed in terms of energy absorption,maximum displacement,peak force and failure behaviour.Results indicated that the effect of temperature on energy absorption of the laminate is negligible although the laminates are embrittling at sub zero temperatures.However it has influence on failure behaviour and displacement.Peak force has increased linearly with increase in laminate thickness from 5 to 10 mm.However it got reduced by 25% when temperature was increased from-20℃ to 100℃,Based on experimental results,laminate perforation energies were predicted using curve fitting equations.Statistical analysis was carried out using Taguchi method to identify the global effects of various parameters on laminate performance and confirmed that the laminate thickness has significant influence as compared to temperature,for the studied range.
文摘The present study focuses on the formulation of new composite consisting of plaster and raffia vinifera particle (RVP) with the purpose to reducing energy consumption. The aim of this study is to test this new compound as an insulating eco-material in building in a tropical climate. The composites samples were developed by mixing plaster with raffia vinifera particles (RVP) using three different sizes (1.6 mm, 2.5 mm and 4 mm). The effects of four different RVP incorporations rates (i.e., 0wt%, 5wt%;10wt%;15wt%) on physical, thermal, mechanicals properties of the composites were investigated. In addition, the use of the raffia vinifera particles and plaster based composite material as building envelopes thermal insulation material is studied by the habitable cell thermal behavior instrumentation. The results indicate that the incorporation of raffia vinifera particle leads to improve the new composite physical, mechanical and thermal properties. And the parametric analysis reveals that the sampling rate and the size of raffia vinifera particles are the most decisive factor to impact these properties, and to decreases in the thermal conductivity which leads to an improvement to the thermal resistance and energy savings. The best improvement of plaster composite was obtained at the raffia vinifera particles size between 2.5 and 4.0 mm loading of 5wt% (C95P5R) with a good ratio of thermo-physical-mechanical properties. Additionally, the habitable cell experimental thermal behavior, with the new raffia vinifera particles and plaster-based composite as thermal insulating material for building walls, gives an average damping of 4°C and 5.8°C in the insulated house interior environment respectively for cold and hot cases compared to the outside environment and the uninsulated house interior environment. The current study highlights that this mixture gives the new composite thermal insulation properties applicable in the eco-construction of habitats in tropical environments.
文摘Kenaf (Hibiscus cannabinus L) consists of various beneficial components like stalks, seeds, leaves, fibers, oils, proteins, allelopathic chemicals, and fiber strands, among other things. Despite the numerous uses of the crop, there is little or no information on optimum agronomic practices such as planting date and N fertilization of the crop in the Upper East Region (UER) of Ghana where the crop is widely cultivated by smallholder farmers. Field experiments were therefore carried out in 2020 and repeated during the 2021 cropping season in the study area. The objective of the study was to determine appropriate planting date and N fertilization for increased kenaf productivity. In each year, the treatments consisted of 3 × 5 factorial combinations of three planting dates (1<sup>st</sup> July, 7<sup>th</sup> July and 14<sup>th</sup> July) and five levels of N (0, 20, 40, 60 and 80 kg/ha) replicated three times. The design of the experiment was a split-plot with the N fertilizer as the main plot and the planting date assigned to sub plot. The results showed that, planting kenaf in early (1<sup>st</sup>) July or N fertilization at the rate of 60 kg/ha increased plant density, stem height, stem diameter, dry bast and core yields in both cropping seasons.
文摘Dynamic image analysis provides an automated evaluation method to determine the size and shape of multiple particles. This method represents a common application for ordinary bulk material. The latest draft of ISO 13322–2:2021 describes the state of the art, but lacks instructions for handling fibrous bulk material. Interlocking fibres complicate the measurement conditions and require a disentanglement of fibrous samples during a pre-dispersion step. A further error source includes the fibre orientation inside the measurement zone of the device. If the thresholding algorithm fails to differentiate between the fibre projection area and the background, a subsequent image optimisation solves the problem. This article addresses the mentioned problems by analysing cotton cellulose and polyacrylonitrile fibres. Besides the execution of a pre-dispersion step, the experiments compare the discrepancies between dry and wet dispersion. Here, the software packages PAQXOS and ImageJ perform the image evaluation. In this case, the wet dispersion setup with a subsequent image evaluation by ImageJ provides comprehensible results.
文摘The growing environmental concerns have led to attention on bio-based composite materials, such as the natural fibres, recycled carbon fibres and bio-based resins. Herein, the bio-based epoxy composites were reinforced with ramie fibre (RF) and recycled carbon fibre (rCF) via inter-layer hybridisation. The dynamic mechanical analysis, tensile, flexural and impact properties characterisation were conducted to analyse the mechanical behaviour of the specimens. Also, the morphology of fractured surface after mechanical tests was studied under a scanning electron microscope. When the volume ratio between RF and rCF was varied from 100/0 to 0/100, the flexural and tensile strength of composites was significantly increased, while the impact strength was reduced. Thus the maximum values of flexural strength (182 MPa) and tensile strength (165 MPa) were observed for rCF reinforced composite, whilst impact strength of 24 kJ/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> was found for RF reinforced composite. Furthermore, the values of storage and loss modulus were increased with the rCF incorporation due to a greater degree of restriction with the addition of rCF into the matrix. The hybridisation was able to combine the specific properties of RF and rCF and optimise the mechanical performance of composites. Therefore, the alternative low-cost green composites are prepared which can replace synthetic materials for semi-structural applications.
