以活性磷酸钙为分散剂制备苯乙烯白球

以活性磷酸钙(TCP)为主分散剂悬浮聚合制备苯乙烯白球,研究了磷酸钙用量及投加方式对白球粒度的影响,采用磷酸钙-有机高分子复合分散体系制得外观质量较好的白球珠粒。     

奇趣珍闻

海底“天才” 格拉西亚诺·菲奥里托和皮特罗·斯各托,曾用食饵训练章鱼,诱其攻击1颗红球或1颗白球 待到某条章鱼学会这一本领后,人们就让旁边水池里的另一条章鱼观察其活动过程。旁观的章鱼一旦被允许向圆球发起进攻,曾见过受训章鱼攻击红球的,就会直趋红球而去,而曾看到受训章鱼攻击白球的,则会缠住白球不放。由于章鱼生来色盲,因此,它们区分两种色球的根据,只是其亮度而非色泽。旁观的章鱼不仅能通过观察把本领学到手,而且其学习速度比训练还来得快。     

苯乙烯与3-(甲基丙烯酰氧基)丙基三甲氧基硅烷位置选择凝胶材料的制备与热性能研究

为了改善聚苯乙烯(PS)的耐热性能,开发兼具有机-无机特性的新型凝胶材料,采用位置选择分子设计与溶胶-凝胶技术,选择含有可水解形成SiO2的官能团的单体3-(甲基丙烯酰氧基)丙基三甲氧基硅烷(MSPMA)与苯乙烯(STY)共聚,利用硅烷的水解、缩聚以共价键的方式在大分子主链上引入纳米SiO2基团.通过改变单体配比合成了一系列SiO2导入位置和导入含量不同的凝胶材料.研究了共聚体的合成、水解过程和纳米SiO2基团在侧链上的分布情况以及对热性能的影响.结果表明:所得凝胶材料具有极好的光学透明性,两种单体在共聚物中几乎可以是交替进行或是按一定的比例进行聚合,形成交替“嵌段”共聚物,水解的SiO2在微纳米级且分散均匀,凝胶材料的热性能随着SiO2含量的增加而提高.     

聚丙烯腈纤维碱法部分水解机理研究

依据价键理论分析了氰基的水解原理,在此基础上提出了聚丙烯腈纤维碱法部分水解的反应机理,指出了该法水解产物不仅含有羧钠基还含有酰胺基和六元环中间体,这些基团都得到了红外光谱的验证。该机理还指出反应过程中纤维颜色的变化与六元环中间体生成的量有关,即水解纤维中六元环中间体含量越多,纤维的颜色越深,这与实验现象相吻合,从而进一步验证了机理的合理性。     

聚丙烯腈纤维碱法部分水解机理研究

依据价键理论分析了氰基的水解原理,在此基础上提出了聚丙烯腈纤维碱法部分水解的反应机理,指出了该法水解产物不仅含有羧钠基还含有酰胺基和六元环中间体,这些基团都得到了红外光谱的验证。该机理还指出反应过程中纤维颜色的变化与六元环中间体生成的量有关,即水解纤维中六元环中间体含量越多,纤维的颜色越深,这与实验现象相吻合,从而进一步验证了机理的合理性。     

一种性能卓越的新型船用轴承材料

华龙材料是以不同的单体共聚的高分子为基础，采用合成稀土金属化合物及多种改性添加剂改性，通过特殊的合成工艺制造而成的均质聚合物，它兼有多种工程塑料（聚酰亚胺类、聚甲醛、聚砜等）之优点，并赋予共聚复合材料以新的特性。在制品成型的同时，形成了高聚物，这与目前常用的高温挤压及注塑成型工艺显然不吲，不但有效避免了高温冲击对材料结构的破坏，     

动力装置辅助系统集散控制研究

本文阐述了动力装置辅助系统计算机集散控制系统的功能原理,介绍了集散控制系统试验样机的软硬件设计及控制系统试验.该系统实现了动力装置辅助系统控制回路的管理、操作、显示的集中,同时实现了功能分散、负荷分散和危险分散,从而有利于提高辅助系统运行的安全可靠性.     

水下不分散混凝土试验研究

对水下不分散混凝土物理力学性能进行了试验研究,推荐配合比的水下不分散混凝土具有粘稠、流动性好、高水下抗分散性和低弹模高塑性的特点,经济可行,施工方便。     

水下不分散混凝土的配比与施工

水下不分散混凝土在国内应用还不十分广泛，施工中利用水下不分散剂，通过一系列技术措施使水下不分散混凝土在实际应用中取得了良好效果。并为以后水下不分散混凝土的推广应用积累了经验。     

水下不分散混凝土配制和施工

水下不分散混凝土的应用有效方便了水下环境中的混凝土施工。通过在混凝土中添加絮凝剂配制成水下不分散混凝土,使混凝土在水下浇筑过程中达到良好的施工性能和使用性能。实践证明,水下不分散混凝土能有效保证施工操作和施工质量。     

船用TA2钛合金晶粒尺寸的超声声速评定

通过对超声纵波声速的测量来评定船用TA2钛合金的平均晶粒尺寸。采用热处理改变了TA2合金试样的晶粒尺寸。实验结果表明,用5P14Z探头测得的纵波声速与晶粒尺寸之间有很好的线性关系。与奥氏体不锈钢、低碳钢等材料不同,随着TA2合金试样晶粒尺寸的增大,纵波声速增大。利用在超声纵波声速和金相测定的晶粒尺寸之间建立的关系图,能够无损评价TA2合金的晶粒尺寸。     

Impact of phytoplankton community size on a linked global ocean optical and ecosystem model

We isolated the effect phytoplankton cell size has on varying remote sensing reflectance spectra (R_rs(λ)) in the presence of optically active constituents by using optical and radiative transfer models linked in an offline diagnostic calculation to a global biogeochemical/ecosystem/circulation model with explicit phytoplankton size classes. Two case studies were carried out, each with several scenarios to isolate the effects of chlorophyll concentration, phytoplankton cell size, and size-varying phytoplankton absorption on R_rs(λ). The goal of the study was to determine the relative contribution of phytoplankton cell size and chlorophyll to overall R_rs(λ) and to understand where a standard band ratio algorithm (OC4) may under/overestimate chlorophyll due to R_rs(λ) being significantly affected by phytoplankton size. Phytoplankton cell size was found to contribute secondarily to R_rs(λ) variability and to amplify or dampen the seasonal cycle in R_rs(λ), driven by chlorophyll. Size and chlorophyll were found to change in phase at low to mid-latitudes, but were anti-correlated or poorly correlated at high latitudes. Phytoplankton size effects increased model calculated R_rs(443) in the subtropical ocean during local spring through early fall months in both hemispheres and decreased R_rs(443) in the Northern Hemisphere high latitude regions during local summer to fall months. This study attempts to tease apart when/where variability about the OC4 relationship may be associated with cell size variability. The OC4 algorithm may underestimate [Chl] when the fraction of microplankton is elevated, which occurs in the model simulations during local spring/summer months at high latitudes in both hemispheres.     

南汇嘴潮滩沉积物粒度特征研究

文中以实测底质采样资料为基础,对南汇嘴沉积物粒度特征进行了分析,并利用Gao&Collins沉积物趋势分析法探讨边滩的沉积物输运趋势。总体上看,样品粒级变化不大,主要以粘土质粉砂、粉砂为主。没冒沙区域由于受到特殊地形以及水流的影响,沉积物以细砂为主;南汇东滩在横向分布上,沉积物粒径逐渐变粗再逐渐变细;南滩受风浪影响,近岸浅滩沉积物颗粒组成较粗,而远岸区域海床颗粒较细。沉积物中值粒径、分选系数和偏度的分布具有一致性,三者相关性较强;浅滩的沉积物粒度特征表现为正偏,分选性较差,分选系数值集中在2左右;南汇嘴区域沉积物运移方向主要是从口外向西输移,汇聚在南汇嘴附近;杭州湾北岸沉积物主要是向东输运,达到芦潮港西侧水域后逐渐转为向南或向南偏东离岸方向运动,对芦潮港附近水下岸坡的冲刷后退起到了一定的影响。     

Comparison of aluminium sandwiches for lightweight ship structures: Honeycomb vs. foam

The use of lightweight aluminium sandwiches in the shipbuilding industry represents an attractive and interesting solution to the increasing environmental demands. The aim of this paper was the comparison of static and low-velocity impact response of two aluminium sandwich typologies: foam and honeycomb sandwiches. The parameters which influence the static and dynamic response of the investigated aluminium sandwiches and their capacity of energy absorption were analysed. Quasi – static indentation tests were carried out and the effect of indenter shape has been investigated. The indentation resistance depends on the nose geometry and is strongly influenced by the cell diameter and by the skin – core adhesion for the honeycomb and aluminium foam sandwich panels, respectively. The static bending tests, performed at different support span distances on sandwich panels with the same nominal size, produced various collapse modes and simplified theoretical models were applied to explain the observed collapse modes. The capacity of energy dissipation under bending loading is affected by the collapse mechanism and also by the face-core bonding and the cell size for foam and honeycomb panels, respectively. A series of low-velocity impact tests were, also, carried out and a different collapse mechanism was observed for the two typologies of aluminium sandwiches: the collapse of honeycomb sandwiches occurred for the buckling of the cells and is strongly influenced by the cell size, whereas the aluminium foam sandwiches collapsed for the foam crushing and their energy absorbing capacity depends by the foam quality. It is assumed that a metal foam has good quality if it has many cells of similar size without relevant defects. A clear influence of cell size distribution and morphological parameters on foam properties has not yet been established because it has not yet been possible to control these parameters in foam making. The impact response of the honeycomb and foam sandwiches was investigated using a theoretical approach, based on the energy balance model and the model parameters were obtained by the tomographic analyses of the impacted panels. The present study is a step towards the application of aluminium sandwich structures in the shipbuilding.     

LiOH吸收剂的成型工艺研究

本文主要论述了LiOH吸收剂的成型工艺研究。根据原料的特殊性质,对比分析了各种成型方法,通过对压制工艺、成型压力、成型粒度、烘干工艺等项的实验研究,最终确定了成型设备、成型压力、成型粒度、升温速度、干燥温度等关键参数,制备出比表面积大、吸收能力强的LiOH吸收剂药粒。     

Modeling Potential Impacts of Beach Replenishment on Horseshoe Crab Nesting Habitat Suitability

Beach replenishment has been proposed to increase nesting habitat for horseshoe crabs, but its environmental consequences may compromise the egg development and viability of this declining species. Horseshoe crab habitat requirements were used to build a habitat suitability model in STELLA to predict the potential impacts of beach replenishment on horseshoe crab eggs. A habitat suitability index (H.S.I.) comprised of six variables (dissolved oxygen, sediment grain size, sand temperature, sand moisture, wave energy, and salinity) was developed and compared between replenished and natural beaches. Sediment grain size and dissolved oxygen were higher in the natural beach, whereas sand temperature and moisture were higher in the replenished beach, resulting in significantly higher suitability of the natural beach (p = 5.39 × 10^?15, df = 30). The model was most sensitive to air temperature, rainfall, tide, and sediment grain size. This model is useful for understanding the processes affecting horseshoe crabs and predicting impacts of coastal management activities on habitat suitability. Based on the results of this model, beach replenishment is not recommended for increasing or improving horseshoe crab habitat, unless care is taken to match fill sediment to natural grain size and color.     

金属基复合材料热机械疲劳寿命影响参数研究

基于细观损伤机理,通过对金属基复合材料在热/机械循环载荷下疲劳破坏的数值模拟,研究了六种参数对疲劳寿命的影响.结果表明:(1)疲劳寿命随着试样尺寸的增大而缩短,但达到临界尺寸,即纤维规模超过25根或者长度超过30倍纤维直径后,疲劳寿命将不受尺寸变化的影响;(2)纤维体积含量影响了材料抗疲劳破坏的能力,疲劳寿命随着纤维体积百分含量的提高而延长;(3)疲劳寿命依赖于纤维强度Weibull分布中形状参数的变化,疲劳寿命随着形状参数的增大而延长;(4)疲劳寿命随着疲劳延性系数的增大而延长,但随着疲劳延性指数绝对值的增大而缩短.     

响应面法模拟轴肩和搅拌针形状对铝合金搅拌摩擦的影响(英文)

The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool probe geometries based on a design matrix. The matrix for the tool designing was made for three types of tools, based on three types of probes, with three levels each for defining the shoulder surface type and probe profile geometries. Then, the effects of tool shoulder and probe geometries on friction stirred aluminum welds were experimentally investigated with respect to weld strength, weld cross section area, grain size of weld and grain size of thermo-mechanically affected zone. These effects were modeled using multiple and response surface regression analysis. The response surface regression modeling were found to be appropriate for defining the friction stir weldment characteristics.     

Experimental study on microbubble ejection method for frictional drag reduction

The formation of air bubbles ejected through a single hole in a flat plate was observed in uniform flow of 2–10 m/s It was confirmed that the size of the air bubbles was governed by main flow velocity and air flow rate. According to previous experiments, the size of the bubbles is an important factor in frictional drag reduction by microbubble ejection. Usually bubbles larger than a certain diameter (for example 1 mm) have no effect on frictional drag reduction. Three different methods were proposed and tested to generate smaller bubbles. Among them, a 2D convex (half body of an NACA 64-021 section) with ejection holes at the top was the best and most promising. The diameter of the bubbles became about one-third the size of the reference ejection on a flat plate. Moreover, the bubble size did not increase with increasing flow rate. This is a favorable characteristic for practical purposes. The skin friction force was measured directly with a miniature floating element transducer, and decreased drastically by microbubble ejection from the top of the 2D convex shape.     

Determination of coal-discharging port dimensions from a shipping point of view

In this paper, the authors examine, in the contest of the enormous expansion of the world coal trade following the Oil Crisis of 1973, the optimal size of coal-discharging terminals. The calculations were based on three shipping-related considerations" the structure of current (and future) coal-carrying vessels; the present size of the world's major coal-loading terminals and their plans for expansion; and the costs of transportation for the various vessel sizes, and constraints in sea-routes. Port-related elements, such as the cost of actual construction etc., were not included in the study. They conclude that the maximum size of a coal carrier is limited by the ability of ports to accommodate it, and that few ports can economically accomodate vessels larger than 150000 dwt. On the other side, vessels of larger than 150000 dwt operate under a number of constraints, meaning in the final analysis, that ports should aim to cater for vessels of around 1500000 dwt and so plan accordingly.