mechanical

摘要： This study explores the fabrication of Fe-based amorphous/crystalline coating by air plasma spraying and its dependency on the coating parameters(plasma power,primary gas flow rate,powder feed rate,and stand-off distance).X-ray diffraction of the coatings deposited at optimized spray parameters showed the presence of amorphous/crystalline phase.Coatings deposited at a lower plasma power and highest gas flow rate exhibited better density,hardness,and wear resistance.All coatings demonstrated equally good resistance against the corrosive environment(3.5wt%NaCl solution).Mechanical,wear,and tribological studies indicated that a single process parameter optimization cannot provide good coating performance;instead,all process parameters have a unique role in defining better properties for the coating by con-trolling the in-flight particle temperature and velocity profile,followed by the cooling pattern of molten droplet before impingement on the substrate.

摘要： Bio-based materials are of great interest owing to their abundance and the immense potential they display as an ideal alternative to widely used industrial construction materials(that directly and indirectly harm the environment).In this scope,an in-depth experimental study is presented here on clay-based materials aimed to enhance their properties through the addition of other bio-based components such as fibers,in the present case alfa fiber.The thermal conductivity and mechanical properties(compressive and flexural tensile strengths)of the composite clay-alfa material are analyzed with the percentage of alfa fiber in the matrix ranging from 0%to 4%.It is concluded that a percentage of alfa fibers between 1%and 2%is the most effective to get the required optimization of thermal and mechanical behavior of this bio-based material.

摘要： The depletion of log resources encourages research into alternative ways to sustain the wood supply.Therefore,the 4-year-old Rubber Research Institute of Malaysia(RRIM)clones series,RRIM 2020 and RRIM 2025,were chosen as potential raw materials for particleboard in this study.The purpose of this study was to assess the effects of planting density and rubber tree clones on the mechanical and physical properties of single-layer particleboard.The planting densities used were low,moderate-low,moderate-high,and high,representing 500,1000,1500,and 2000 trees/ha,respectively.Prior to manufacturing,the RRIM 2000 series clone trees were harvested,cut,chipped,flaked,and screened.The mechanical and physical properties were evaluated in accordance with the Japanese Industrial Standard(JIS A 5908-2003).The findings revealed that both planting density and clone had a significant impact on the mechanical and physical properties of particleboard with a thickness of 10 mm and a density of 700 kg/m3.RRIM 2020 specimens with low planting density had superior modulus of elasticity(MOE),modulus of rupture(MOR),and internal bonding(IB)values of 2415,19,and 1.7 MPa,respectively.Furthermore,moderate-low planting density demonstrated the lowest thickness swelling(TS)and water absorption(WA)values and was comparable to control particleboard from commercial clone Prang Besar(PB),PB260.In terms of rubber clones,RRIM 2020 particleboard met the minimum requirements of the JIS standard for mechanical properties and outperformed RRIM 2025.This study recommended a low planting density of 500 trees/ha and the RRIM 2020 clone as a suitable raw material for particleboard manufacturing with a ten percent urea formaldehyde resin content.

摘要： In this study, the characteristics of Graphite/Epoxy Composites (GECs) are evaluated from mechanical perspectives. Different weight percentages of graphite were used (0 - 7 wt%) for tensile and hardness experiments. Then the findings were discussed to ascertain the optimum mixing ratio of the graphite with the epoxy. The primary finding of this study is that the graphite weight fraction has a substantial impact on the composites’ mechanical performance. At a low percentage (1 wt%), the graphite has little influence on the tensile behaviour. An intermediate weight percentage of the graphite is considered optimum for mechanical performance in the epoxy composites as it slightly reduces the tensile properties and significantly improves the hardness. Micrographs of the fractured surface of specimens showed many signs that clearly explained why fractures had occurred. For instance, when graphite/epoxy composite contained a low proportion of graphite, the cleavage failure was very easy to observe because there was no sign of aggregation or the detachment of fillers.

摘要： [Objectives]To study the effect of mechanical harvesting of main crop on soil rolling and yield of ratooned rice.[Methods]In this study,the harvesting method was optimized and improved through field research and theoretical research.[Results]Compared with farmers'habits,the mechanical harvesting method could significantly increase the working area per unit time and reduce the rolling area in the field,but it would increase the rolling rate of the land or transfer area.At the same time,the optimization method could reduce the soil bulk density in the primary rolling area,but it had no significant impact on soil compactness.[Conclusions]Compared with the farmer's customary method,the optimization method could reduce the crushing and damage of rice piles in the field,increase the seedling rate and panicle extraction rate,thus increasing the yield of rice in the ratooning season.

摘要： Hydrostatic cyclic expansion extrusion(HCEE) process at elevated temperatures is proposed as a method for processing less deformable materials such as magnesium and for producing long ultrafine-grained rods. In the HCEE process at elevated temperatures, high-pressure molten linear low-density polyethylene(LLDPE) was used as a fluid to eliminate frictional forces. To study the capability of the process,AM60 magnesium rods were processed and the properties were investigated. The mechanical properties were found to improve significantly after the HCEE process. The yield and ultimate strengths increased from initial values of 138 and 221 MPa to 212 and 317 MPa, respectively.Moreover, the elongation was enhanced due to the refined grains and the existence of high hydrostatic pressure. Furthermore, the microhardness was increased from HV 55.0 to HV 72.5. The microstructural analysis revealed that ultrafine-grained structure could be produced by the HCEE process. Moreover, the size of the particles decreased, and these particles thoroughly scattered between the grains. Finite element analysis showed that the HCEE was independent of the length of the sample, which makes the process suitable for industrial applications.

摘要： In order to study the mechanical and deformation characteristics of rubber concrete under repeated loading,50 cycles of high-stress equal amplitude cyclic loading and uniaxial compression tests were carried out on 30 concrete specimens of 5 groups.The change of uniaxial mechanical properties and the deformation during cyclic loading of normal concrete(NC)and rubber concrete(RC)with 5%,10%,15%,and 20%content were analysed.The results show that the peak stress and modulus of elasticity decrease and the peak strain increases with the increase of rubber content.After cyclic loading,the degradation degree of NC peak stress and elastic modulus reached 11.0%and 36.8%respectively.This study can provide a basis for the application of rubber concrete.

摘要： Firstly,this paper analyzes the necessity of highway engineering construction machinery and equipment management,discusses the configuration management of highway engineering machinery and equipment,and then puts forward the problems existing in the management and maintenance of highway engineering machinery construction equipment.Finally,the management and maintenance measures of highway engineering machinery construction equipment are discussed in a targeted manner.

摘要： Rhythmic oscillatory patterns sustain cellular dynamics, driving the concerted action of regulatory molecules, microtubules, and molecular motors. We describe cellular microtubules as oscillators capable of synchronization and swarming, generating mechanical and electric patterns that impact biomolecular recognition. We consider the biological relevance of seeing the inside of cells populated by a network of molecules that behave as bioelectronic circuits and chromophores. We discuss the novel perspectives disclosed by mechanobiology, bioelectromagnetism, and photobiomodulation, both in term of fundamental basic science and in light of the biomedical implication of using physical energies to govern (stem) cell fate. We focus on the feasibility of exploiting atomic force microscopy and hyperspectral imaging to detect signatures of nanomotions and electromagnetic radiation (light), respectively, generated by the stem cells across the specification of their multilineage repertoire. The chance is reported of using these signatures and the diffusive features of physical waves to direct specifically the differentiation program of stem cells in situ, where they already are resident in all the tissues of the human body. We discuss how this strategy may pave the way to a regenerative and precision medicine without the needs for (stem) cell or tissue transplantation. We describe a novel paradigm based upon boosting our inherent ability for self-healing.