Loop细分曲面的数控粗加工刀具路径生成方法

以Loop细分曲面为例,介绍了细分曲面的三轴数控刀具路径生成方法。首先根据细分曲面的网格迭代特性,提出了一种Z-map模型技术和一种包络细分曲面的覆盖曲面方法,然后根据极限曲面与覆盖曲面的关系,调整网格顶点生成最终覆盖曲面,讨论了细分曲面的粗加工刀具路径生成方法。同时,为了解决加工干涉问题,提出了一种加工干涉检查和纠正方法。     

奇奇核168Lu三轴超形变带的研究

采用TRS方法对^168Lu新发现的一条三轴超形变转动带进行了理论计算，在理论上进一步证实了其存在的三轴超形变，并通过三维自洽计算得到了其形变参数值，结果与文献一致．     

Microwave-assisted synthesis, anticonvulsant activity and quantum mechanical modelling of N-（4-bromo-3-methylphenyl） semicarbazones

Objective： To study the effect of halo substitution on disubstituted aryl semicarbazones on the anticonvulsant potential and model the activity based on quantum mechanics. Methods： A series of twenty-six compounds of N^4-（4-bromo-3-methylphenyl） semicarbazones were synthesized and evaluated for the anticonvulsant activity in the maximal electroshock seizure （MES） and subcutaneous pentylenetetrazole （scPTZ） seizure threshold tests. Some potential compounds were also tested in the subcutaneous strychnine （scSTY） and subcutaneous picrotoxin （scPIC） seizure threshold tests. The synthesized compounds were tested for behavioral impairment and CNS （central nervous system） depression in mice. Quantum mechanical modelling was carried out on these compounds to gain understanding on the structural features essential for activity. Results： Some compounds possessed broad spectrum anticonvulsant activity as indicated by their effect in pentylenetetrazole, strychnine, picrotoxin and maximal electroshock seizures models in resemblance to other aryl semicarbazone derivatives reported earlier. The higher the difference in HOMO （highest occupied molecular orbital） and LUMO （lowest unoccupied molecular orbital） energy levels was, the greater was the activity profile. Conclusion： The pharmacophoric requirements for compounds to exhibit anticonvulsant activity that includes one aryl unit in proximity to a hydrogen donor-acceptor domain and an electron donor have been justified with the molecular orbital surface analysis of the synthesized compounds.     

Nanocontainer aqueous systems for removing polymeric materials from marble surfaces: A new and promising tool in cultural heritage conservation

The present study dealt with the characterisation of marble surfaces coated by three kinds of polymeric material usually employed in stones conservation and with the evaluation of the removal of these coatings from the surfaces by means of new nanocontainer aqueous systems constituted of micellar solutions (MS) and oil-in-water microemulsions (MC). The polymeric coatings were also subjected to accelerated artificial ageing in order to detect possible effects associated to natural photochemical ageing. The aim of the work was the assessment of the performance of such nanocontainer aqueous systems taking acetone (Ac) as a reference “traditional” solvent for the removal procedure. The characterisation was carried out by means of Scanning Electron Microscopy (SEM) and Environmental Scanning Electron Microscopy (ESEM), Fourier Transform Infra-Red (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies and the results obtained showed that the performance of these innovative methods based on nanocontainer aqueous systems can be considered highly promising in the view of a “green approach” to the conservation of cultural heritage.     

Impact absorption of tennis shoe-surface combinations

The aim of this study was to investigate, for typical shoes and surfaces used in tennis, the relative role of the shoe and surface in providing cushioning during running. Five test surfaces ranging from concrete to artificial turf were selected, together with two shoe models. Impact absorbing ability was assessed mechanically using drop test procedures and biomechanically using peak magnitude and rate of loading of impact force and peak in-shoe pressure data at the lateral heel. Differences in biomechanical variables between shoe-surface combinations were identified using a two-way ANOVA (p < 0.05). Mechanical test results were found to rank the surfaces in the same order regardless of the shoe model, suggesting that the surface is influential in providing cushioning. However, for all mechanical and biomechanical (p < 0.05) variables representing impact absorbing ability, it was found that the difference between shoes was markedly greater than the differences between surfaces. The peak heel pressure data were found to rank the surfaces in the same order as the mechanical tests, while impact force data were not as sensitive to the changes in surface. Correlations between mechanical and biomechanical impact absorption highlighted the importance of testing the shoe-surface combination in mechanical tests, rather than the surface alone. In conclusion, mechanical testing of the shoe-surface combination was found to provide a strong predictor of the impact absorbing ability during running if pressure data were used. In addition, for typical shoe-surface combinations in tennis, the shoe was found to have more potential than the surface to influence impact loading during running. Finally, in-shoe pressure data were found to be more sensitive than force plate data to changes in material cushioning.     

H3(-1)中具有一个常主曲率的曲面

文章讨论H 3(-1)了中具有一个常主曲率的曲面,得到了另一主曲率与该常主曲率之间的关系。     

自由曲面的平面展开

1　Introduction　PlanardevelopmentofacurvedsurfaceisbroadlyusedinCAGDandCAD .Accordingtotheirdevelop ment ,surfacesaredividedintodevelopablesurfacesandnon developablesurfaces .Mostofcurvedsurfacesarenon developable ,butbroadlyusedinengineering ,suchasaircraftwings ,laminaofturbine ,fluidsur face .Howeverthedesignandhandlingofcurvedsur faceareverydifficult.Inordertopredigestthecom plexityofdesign ,planardevelopingisintroduced .Non developablesurfacescannotbedevelopedontoaplanewithoutstretch…     

山水画皴法的形式美及其发展

中国山水画的皴法 ,是历代山水画家外师造化、摹写真山实水提炼出来的语言形式 ,具有独特的审美特征。皴法的程式化 ,即是艺术发展的规律性总结 ,亦是为表现主题服务的 ,同时也是不断变化、丰富和发展的。     

广义Robertson-Walker时空中类空超曲面的体积与Gauss映照

利用Gauss映照研究具有紧致单连通纤维的广义Robertson-Walker时空中的类空超曲面.在假定Gauss映照为有限的条件下,得到了超曲面体积的估计,并确定了当体积达到上界与下界时超曲面的结构.所得结果推广了由Aledo与Alias得到的有关de Sitter时空中相应的结论.     

Effect of the coefficient of friction of a running surface on sprint time in a sled-towing exercise

This study investigated the effect of the coefficient of friction of a running surface on an athlete's sprint time in a sled-towing exercise. The coefficients of friction of four common sports surfaces (a synthetic athletics track, a natural grass rugby pitch, a 3G football pitch, and an artificial grass hockey pitch) were determined from the force required to tow a weighted sled across the surface. Timing gates were then used to measure the 30-m sprint time for six rugby players when towing a sled of varied weight across the surfaces. There were substantial differences between the coefficients of friction for the four surfaces (μ = 0.21–0.58), and in the sled-towing exercise the athlete's 30-m sprint time increased linearly with increasing sled weight. The hockey pitch (which had the lowest coefficient of friction) produced a substantially lower rate of increase in 30-m sprint time, but there were no significant differences between the other surfaces. The results indicate that although an athlete's sprint time in a sled-towing exercise is affected by the coefficient of friction of the surface, the relationship relationship between the athlete's rate of increase in 30-m sprint time and the coefficient of friction is more complex than expected.