摘要：Many studies have evaluated the effects of additives such as nano-silica (NS), micro-silica (MS) and polymer fibers on optimizing the mechanical properties of concrete, such as compressive strength. Nowadays, with progress in cement industry provides, it has become possible to produce cement type I with strength classes of 32.5, 42.5, and 52.5 MPa. On the one hand, the microstructure of cement has changed, and modified by NS, MS, and polymers;therefore it is very important to determine the optimal percentage of each additives for those CSCs. In this study, 12 mix designs containing different percentages of MS, NS, and polymer fibers in three cement strength classes(CSCs)(32.5, 42.5, and 52.5 MPa) were designed and constructed based on the mixture method. Results indicated the sensitivity of each CSCs can be different on the NS or MS in compressive strength of concrete. Consequently, strength classes have a significant effect on the amount of MS and NS in mix design of concrete. While, polymer fibers don’t have significant effect in compressive strength considering CSCs.

摘要：The method of determining coal pillar strength equations from databases of stable and failed case histories is more than 50 years old and has been applied in different countries by different researchers in a range of mining situations. While common wisdom sensibly limits the use of the resultant pillar strength equations and methods to design scenarios that are consistent with the founding database, there are a number of examples where failures have occurred as a direct result of applying empirical design methods to coal pillar design problems that are inconsistent with the founding database. This paper explores the reasons why empirically derived coal pillar strength equations tend to be problem-specific and should be considered as providing no more than a pillar strength ‘‘index." These include the non-consideration of overburden horizontal stress within the mine stability problem, an inadequate definition of supercritical overburden behavior as it applies to standing coal pillars, and the non-consideration of overburden displacement and coal pillar strain limits. All of which combine to potentially complicate and confuse the back-analysis of coal pillar strength from failed cases. A modified coal pillar design representation and model are presented based on coal pillars acting to reinforce a horizontally stressed overburden, rather than suspend an otherwise unstable self-loaded overburden or section, the latter having been at the core of historical empirical studies into coal pillar strength and stability.

摘要：Aluminum 5052(Al 5052)-stainless steel 316(SS 316)plates were explosively cladded with Al 1100,pure copper and SS 304 *** operational parameters viz.,standoff distance,explosive mass ratio(mass ratio of the explosive to the flyer plate)and inclination angle were varied and the results were *** advent of interlayer relocates the lower boundary of the welding window,and enhances the welding regime by 40%.A triaxial welding window,considering the influence of the third operational parameter,was developed as *** of interlayer transforms the continuous molten layer formed in the traditional Al 5052-SS 316 explosive clad interfaces into a smooth interface devoid or with a slender presence of intermetallic *** microhardness,ram tensile and shear strengths of the interlayered clads are higher than those of the traditional explosive clads,and the maximum values are witnessed for stainless steel interlaced Al 5052-SS 316 explosive clads.

摘要：Background: The lower extremity muscle strength has been shown to be weaker in patients with diabetes mellitus, primarily due to the effects of diabetic polyneuropathy, a common diabetic complication. With respect to assessments of the lower extremity muscle strength, reference values for the knee extension force in healthy Japanese subjects have been reported. The clinical significance of applying knee extension force in the assessment of efficacy of exercise therapy and patient education has also been demonstrated, and the use of an individualized approach in physical exercise based on the quantitative assessment of the lower extremity muscle strength is becoming one of the most important strategies for promoting effective rehabilitation. Methods: The study is a multicenter, cross-sectional investigation. We will measure the knee extension force and evaluate the diabetic polyneuropathy in patients with type 2 diabetes using uniform equipment and methodology at all centers. We will compare the knee extension force between the subjects with and without diabetic polyneuropathy and will investigate the associations between the knee extension force and both glycemic control and exercise habits. The trial registration is UMIN CTR (UMIN000002810). Discussion: The lower extremity muscle strength has been insufficiently investigated in Japanese patients with diabetes. This study was designed to establish reference values for the knee extension force in Japanese diabetic patients with and without diabetic polyneuropathy.

摘要：The demand for natural gas in the world is increasing day by day. The efficient and flexible LNG becomes the preferred method for natural gas storage and transportation and has gradually entered people’s daily life. The enclosure system is the key core of LNG transport and storage vessels for storage of LNG at -163°C for isolation and thermal insulation. A new type of flat half-film prismatic LNG enclosure system has been developed for the shortcomings of the existing LNG cargo enclosure system. Through the breakthrough and mastery of key core technologies such as the overall layout and integration of the system, anti-leakage technology, liquid tank fixing technology, and large-scale friction stir welding (P-FSW) flat-line pipeline development technology, we’ll strive to fill the gap in the intelligent construction technology of large aluminum alloy tanks in China. The tank was subjected to water vapor test and numerical simulation. The results show that the structural strength of the FSP-LNG tank meets the strength check standard of IGC Code.

摘要：In this study, control factors which included aspect ratio of fibres, volume fraction of fibres and fibres orientation were the focus for determining the optimum tensile strengths of coir fibres reinforced polyester resin composites. After using Archimedes principle to determine the volume fraction of fibres, tensile test was conducted on the samples of treated and untreated coir fibres reinforced polyester resin composites, respectively. For the optimum properties to be obtained, a Universal Testing Machine-TUE-C-100 was used for the conducted tensile tests which established the levels of control factors settings for quality characteristics needed to optimize the mechanical properties being investigated. Applying Taguchi robust design technique for the greater-the-better, the highest signal-to-noise ratio (S/N ratio) for the quality characteristics being investigated was obtained employing Minitab 16 software. The optimum values of the control factors were established for treated coir fibres reinforced polyester resin composites and untreated coir fibres reinforced polyester resin composites. The treated coir fibres reinforced polyester matrix composite has the optimum tensile strength of 42.7 N/mm2 while the untreated coir fibres reinforced matrix composite has the optimum tensile strength of 21.9 N/mm2. The reinforcement combinations of control factors contribute greatly to the tensile properties, and the treated coir fibres reinforced polyester composites are stronger in tension than the untreated coir fibres reinforced polyester composites.

摘要：Seashells,commonly referred to as nature’s armors against predatory attacks,have been serving as the inspirations for designing strong and tough engineering *** studies on conch shells have been focused on the shell body *** conch spines which are evenly distributed at the tail of conch shell are generally accepted as the decoration,enabling conch shells as art *** we report a new finding that nature uses curved reinforcements,different from the straight ones in conch body parts,to construct conch spines which exhibit 30%increase in fracture strength compared to conch shell body *** curved lamellae not only endow conch spines with pyramid-shape but also add extra shielding to the *** equilibrium state,the curved lamellar configuration withholds 3 times higher loading than the straight *** finding uncovered nature’s wisdom in constructing seashells and provides an additional design guideline for utilizing curved reinforcements to achieve multifunctionalities and superior mechanical prowess.

摘要：A novel Ni-Cr-Si-B filler metal with the cluster formula of[Cr-Ni12]B2Cr+[B-Ni8Cr]BSi Cr based on the cluster-plus-glue-atom model was designed for vacuum brazing GH4169 *** effect of brazing temperature and brazing time on microstructure and shear strength of GH4169 alloy joints was *** brazed seam was mainly composed ofγ-Ni solid solution.(Nb,Ti)-rich phase and(Cr,Nb,Mo)-rich borides distributed in diffusion *** diffusion and aggregation of B,Cr,Nb,and Mo resulted in the variation of phase contrast and morphology of *** precipitations in the joint brazed at1240℃consisted of borides,Laves phase andδ*** shear strength of joints was principally dominated by the brittle precipitations in diffusion zone,and the homogenization of microstructure improved the room-temperature shear strength to 820 MPa with the high-temperature shear strength of 627 MPa for the joint brazed at 1240℃/20 *** joint fractured in diffusion zone and brazed seam,and the existence of borides and Laves phase in diffusion zone provide the potential origin for crack growth.

摘要：A new kind offl biomedical titanium alloy, Ti-35Nb-4Sn-6Mo-9Zr, composed of non-toxic elements Nb, Mo, Zr and Sn with lower elastic modulus and higher strength was designed based on d-electron alloy design theory and JMatPro software using orthogonal experiment. The microstructure and basic mechanical properties of designed alloy were investigated. The results show that the alloy is composed of single fl equiaxed grains after solution treatment at 800 ~C. Compared with Ti-6A1-4V, the mechanical properties of the designed alloy are more excellent： E=65 GPa, σb=834 MPa, σ0.2=802 MPa, and σ=11%, which is expected to become a promising new type implanted material. The research approach adopted can reduce the experimental time and cost effectively, and get the ideal experimental results.

摘要：采用电子束熔化(EBM)成形工艺,制造具有可控多孔结构的Ti6Al4V植入体,分析测试其微观孔隙结构特征、孔隙率以及力学性能。扫描电镜观测结果表明,所制备的钛合金植入体孔隙结构特征与设计结构相符合,证明EBM技术能够实现钛合金植入体孔隙结构的控制;测得多孔植入体的孔隙率为60.1%,相应的抗压强度为163MPa,弹性模量为14GPa,与人体骨组织弹性模量相近。利用改进的碱热处理方法进行表面改性,并浸泡在模拟体液中以诱导磷灰石的形成。体外细胞培养试验结果表明,培养7d后成骨细胞在改性的试件表面大量粘附、生长、增殖。