仿生机器鱼运动方向的模糊控制研究

结合仿生机器鱼运动的三种转弯模式,设计了一种用于机器鱼运动方向控制的模糊控制器,并阐述了具体算法的实现。实验结果表明,该方法是有效的,且具有较好实时性,能够满足多仿生机器鱼协调协作研究的需要,并为未来机器鱼的实际应用奠定了良好基础。     

基于增强式学习的仿生机器鱼避障控制

研究了仿生机器鱼的自主避障控制,提出了一种集成超声和红外传感器的仿生机器鱼系统设计方案,为机器鱼安装了3个超声传感器和3个红外传感器.针对此仿生机器鱼系统,提出了一种基于增强式学习的仿生机器鱼自主避障控制策略,给出了状态集和行为集,采用当场奖励和延时奖励相结合的方法,通过学习获得了有效的状态行为组合.仿真实验验证了学习结果的有效性.     

激光照鱼眼测定鱼鲜度

日本长崎水产公司最近研制出一种激光仪器,可用于测定鱼的鲜度。其测定原理是,首先用激光照射鱼的眼睛,然后根据鱼眼反射光线的不同来测定鱼的新鲜程度。 据报道,一般刚死的鱼,其眼睛反射光线     

鱼水雷计量保障工作的几点思考

文章简要介绍了新型鱼水雷测试设备计量保障工作的特点,并针对鱼水雷测试设备计量管理工作中存在的问题,从计量监督管理和计量技术保障两个层面探讨了鱼水雷测试设备计量保障工作的开展思路,为下一步的计量保障工作指明了方向。     

行波推进仿生机器鱼

介绍5种常见的鱼类游动模式,分析讨论仿生机器鱼的生物学原型。基于对裸臀鱼属（gymnarchus niloticus）与裸背鳗属（gymnotus carapo）活体鱼的实验研究,建立了长背鳍扭转行波动态曲面的数学模型。依靠长鳍行波实现推进与控制的新型仿生机器鱼,其基本结构是“刚性身体”与“柔性背鳍”的组合,这有利于改善现有摆动式机器鱼的技术性能。裸臀鱼属与裸背鳗属鱼类可作为发展特种机器鱼潜艇的生物学原型,以提高现行水下航行器的效率和机动性能。     

快报

<正>熏鱼、鱼干将有地方标准江苏省卫生和计划生育委员会近日出台《食品安全地方标准熟制风味鱼》征求意见稿,拟对市场上常见的熏鱼、鱼千制定食品安全地方标准。据了解,熟制风味鱼产品是江苏食品市场上畅销的食品。目前,熟制风味鱼产品尚无食品安全国家标准,制定该项标准可以填补食品安全地方标准空白。据悉,江苏省卫计委之前向省内熟制风味鱼生产企业寄送《关于调查了解全省熟制风味鱼产品基本情况的函》55份,     

仿鱼机器人S形快速起动的推进效率分析

基于白斑狗鱼主动/被动S形起动的体干曲线的摆动规律,为研制的仿鱼机器人建立S形起动的运动方程.通过流体举力、边界层摩擦阻力和纵向附加质量力等水动力计算,分析仿鱼机器人S形起动的水下推进效率.利用主动/被动S形起动的多步态仿真实验,给出仿鱼机器人动能、输入功率和推进效率等水下机动性能指标,为仿鱼机器人的水下机动推进实验研究和优化设计提供理论依据.     

机器鱼在矿井透水事故中的应用

以机器鱼为载体,结合各种传感设备实现矿井透水事故后的水下探测。主要介绍机器鱼的结构及运行状态,在软件层次说明如何实现机器鱼再水下的自主导航和地图形成。     

四倍体鱼的种质改良研究

β－ａｃｔｉｎ基因启动子驱动的草鱼生长激素基因ｃＤＮＡ－“全鱼”基因ｐＣＡｇｃＧＨｃ用显微注射方法导入四倍体鱼卵,获得了生长快,个体硕壮的转基因四倍体鱼。２４０日龄时,转基因鱼平均体重为３０２．７ｇ,是对照鱼的３．１倍,平均体长是对照的１．３４倍,燕可从部分转基因雄鱼挤出精液,而对照鱼尚无此现象。对１９尾转基因四倍体雄鱼的精液和尾鳍ＤＮＡ做ＰＣＲ检测,外源基因和的阳性率分别为９４．７％和５２．６％     

RS/GIS支持下的柔鱼中心渔场时空动态迁移研究

根据1998-2001年的西北太平洋地区(35°N-45°N,140°E-170°W)巴特柔鱼资源调查与生产的实际情况对柔鱼捕捞作业中心的迁移路线进行研究,并利用同期的SST、SWiFs遥感反演资料,借助GIS的功能,分析了柔鱼中心渔场形成与表层水温、叶绿素a海洋要素场之间的关系,揭示西北太平洋柔鱼中心渔场的环境特征,以期为我国西北太平洋海区的鱿鱼生产服务。     

Size Distribution of Gold Nanoparticles Used by Small Angle X-ray Scattering

ABSTRACT

The size distribution of gold nanoparticles was estimated based on the scattering intensity data obtained from small angle X-ray scattering (SAXS) and compared with the result of micrographs by transmission electron microscopy. The slope of the Guinier plot was used to estimate the mean size assuming a narrow particle size distribution. When the size distribution is narrow, the mean size can be easily obtained from slope of a Guinier plot of scattering data within 10% error. Additionally, assuming a lognormal size distribution, the size distribution and the mean size can be calculated using the experimental SAXS data in the fitting analysis. The histogram method, which utilizes the coefficient matrix of scattering intensity, was also applied to the estimation of the size distribution, and this method could be useful for a rough estimate of the size distribution.     

Effects of specimen and grain sizes on compression strength of annealed wrought copper alloy at room temperature

Variations in compression yield strength of annealed wrought CuAl7 copper alloy with specimen diameter (t) in 1–10 mm range and grain size (D) in 24–172 μm range were investigated. Both grain size effect and feature size effect could be observed. The compression yield strength increased with a reduction in grain size or specimen diameter, and varied with the t/D ratio in no particular manner. However, when t was held constant, the compression yield strength increased as the ratio increased. When D was held constant, the strength decreased as the ratio increased. The Hall–Petch relationship between the compression yield strength and the grain size was found to depend on the specimen diameter. The effect of feature size was greater than that of grain size. A new model of the relationship between the compression yield strength and the grain size, specimen diameter, and size factor has been built. The predicted results of the model agreed well with the experimental results. The fit of the model was better than that of a model based on the relationship between the compression yield strength and the grain size and specimen diameter only.     

Particle size distribution and dislocation density determined by high resolution X-ray diffraction in nanocrystalline silicon nitride powders

Two silicon nitride powders were investigated by high resolution X-ray diffraction. The first sample was crystallized from the powder prepared by the vapour phase reaction of silicon tetrachloride and ammonia while the second was a commercial powder produced by the direct nitridation of silicon. Their particle size and dislocation density were obtained by the recently developed modified Williamson–Hall and Warren–Averbach procedures from X-ray diffraction profiles. Assuming that the particle size distribution is log-normal the size distribution function was calculated from the size parameters derived from X-ray diffraction profiles. The size distributions determined from TEM micrographs were in good correlation with the X-ray results. The area-weighted average particle size calculated from nitrogen adsorption isotherms was in good agreement with that obtained from X-rays. The powder produced by silicon nitridation has a wider size distribution with a smaller average size than the powder prepared by vapour phase reaction. The dislocation densities were found to be between about 10¹⁴ and 10¹⁵ m⁻².     

Size effect on strength of alumina agglomerates

Abstract

The size effect on strength of alumina agglomerates was examined, and the applicability of the often used size effect laws was discussed. It is concluded that there is a significant energetic size effect, which shows that the Weibull statistical size effect does not apply. However, the size effect on the tensile strength of the agglomerates examined can be addressed well by the energetic–statistical size effect law.     

Effect of Granulating Method on Particle Size Distribution of Granules and Disintegrated Tablets. I

Abstract

The average particle size and distribution of granules were found to be dependent on the granulating method. The slugging method produced the widest particle size distribution and the largest average particle size, while the microgranulating method produced the narrowest distribution and the smallest average particle size. The average particle size of dexamethasone granules produced by wet granulating, microgranulating and slugging methods, were reduced on compaction by fragmentation. Of the three, the granules prepared by the slugging method, exhibited maximal average size reduction on compaction. On the other hand, the average particle size of sulfadiazine microgranulates and sulfadiazine slugs were enlarged by consolidation during compaction.     

Effect of TiH2 particle size distribution on aluminum foaming using the powder metallurgy method

TiH₂ decomposes over a range of temperatures strongly influenced by diverse factors including particle size. In the present research, a systematic study of the dehydrogenation behavior of TiH₂ powder of different particle size distribution was undertaken with the aid of thermogravimetric analysis. The effect of this parameter on aluminum foaming was evaluated. It was found that when TiH₂ exceeds a critical particle size (around 50 μm), dehydrogenation occurs as a single desorption event with onset temperatures around 500 °C. The reduction of particle size, besides reducing the onset of hydrogen release, decreases the dehydrogenation rate. As a result, the first dehydrogenation event gets sharper and tends to overlap with the second with increasing particle size. The use of selected powders on foaming showed that the final foam expansion and porosity features, such as pore size, pore density, and homogeneity are largely influenced by the particle size distribution of the foaming powder. TiH₂ of the largest particle size was the most suitable for foaming pure aluminum.     

Biocompatibility and Biodegradation of novel PHB porous substrates with controlled multi-pore size by emulsion templates method

PHB porous substrates were prepared based on the mono-membrane fabricated by emulsion templates method. The key factors of the method affecting the pore size and porosity of the PHB porous substrates were studied. The surface of PHB porous substrates were investigated by scanning electron microscope (SEM), which showed the even pore size and regular arranged pore. The transect of the PHB porous substrates prepared using the templates method was good. Moreover, the effects of variation of surfactant content (P%) and water content (R) on the pore size and porosity of PHB films were discussed. Preliminary studies showed that when P% is less than 20%, the pore size made by emulsion templates ranged from 5 μm to 30 μm with the value of P increasing. As P% is up to 20%. It was interesting to see that the porous substrates had muti-pore size distribution, i.e., median pore sizes were about 5 μm and inside the wall of pore, there existed numerous micro-pores size can be controlled from 100 nm to 500 nm only by adjusting the parameter R of the microemulsion. The cell-compatibility was evaluated via Chinese Hamster Lung (CHL) fibroblast cultivation in vitro. The Cells were cultured on both the mono-pore size membrane prepared by emulsion templates and the multi-pore size membrane prepared by microemulsion templates. It can be seen that the cells cultured on multi-pore size membrane stretched their morphology and proliferated better than that of mono-pore size membrane. These results indicated that the multi-pore size membrane had better cell-compatibility and was more suitable for tissue engineering. The degradation experiment indicated that the degradation of PHB porous substrates were accelerated by enzyme in vitro and the porous configuration was favorable to its degradation.     

Effect of particle size on microstructure and strength of porous spinel ceramics prepared by pore-forming <Emphasis Type="Italic">in situ</Emphasis> technique

The porous spinel ceramics were prepared from magnesite and bauxite by the pore-forming in situ technique. The characterization of porous spinel ceramics was determined by X-ray diffractometer (XRD), scanning electron microscopy(SEM), mercury porosimetry measurement etc and the effects of particle size on microstructure and strength were investigated. It was found that particle size affects strongly on the microstructure and strength. With decreasing particle size, the pore size distribution occurs from multi-peak mode to bi-peak mode, and lastly to mono-peak mode; the porosity decreases but strength increases. The most apposite mode is the specimens from the grinded powder with a particle size of 6·53 μm, which has a high apparent porosity (40%), a high compressive strength (75·6 MPa), a small average pore size (2·53 μm) and a homogeneous pore size distribution.     

Role of particle size of alumina on the formation of aluminium titanate as well as on sintering and microstructure development in sol–gel alumina–aluminium titanate composites

With a view to develop low temperature fine grained alumina–aluminium titanate composite, influence of alumina particle size on the temperature of formation of the aluminium titanate, sintering behaviour and microstructure development of alumina–aluminium titanate composite prepared through a sol–gel core shell approach is reported. The alumina matrix composite containing 20 wt% aluminium titanate has been prepared from alumina powders having different average particle size in the range 300–600 nm. The alumina particle size appears to have no significant influence on the formation temperature of in situ formed aluminium titanate. However, the microstructural analysis of the dense ceramic showed that the average grain size of the alumina–aluminium titanate composite increases with increase in the alumina particle size. XRD analysis indicated the absence of rutile titania in the sintered composite ensuring complete formation of aluminium titanate. Smaller starting alumina particle size led to finer grain size composites. The present study therefore shows that although the starting particle size of alumina has no significant role on the lowering of formation temperature of aluminium titanate, it does influence the microstructure of the composite.     

Identification of the effective grain size responsible for the ductile to brittle transition temperature for steel with an ultrafine grain size ferrite/cementite microstructure with a bimodal ferrite grain size distribution

This research investigated the mechanism responsible for the ductile to brittle transition temperature for the newly developed steels with a bimodal, ultrafine grain size, ferrite/cementite microstructure (UGF/C), which are produced by caliber warm rolling followed by annealing. The microstructure of the steel was characterised. Charpy impact tests were carried out in the temperature range from 373 K to 4.2 K and the fracture surfaces were analysed. The effective grain size responsible for the ductile-to-brittle transition temperature corresponded to the grain size of the large grain size regions. The mechanism of this phenomenon was attributed to the characteristics of the grain boundaries, as high angle grain boundaries are more effective in impeding cleavage crack propagation. The grain size of the large grain size regions was important in determining the DBTT because these grain boundaries were high angle grain boundaries, whereas the small gain size regions were dominated by the low angle grain boundaries.