Shape optimization of axisymmetric solids with the finite cell method using a fixed grid

In this work, a design procedure extending the B-spline based finite cell method into shape optimization is developed for axisymmetric solids involving the centrifugal force effect. We first replace the traditional conforming mesh in the finite element method with structured cells that are fixed during the whole design process with a view to avoid the sophisticated re-meshing and eventual mesh distortion.Then, B-spline shape functions are further implemented to yield a high-order continuity field along the cell boundary in stress analysis. By means of the implicit description of the shape boundary, stress sensitivity is analytically derived with respect to shape design variables. Finally, we illustrate the efficiency and accuracy of the proposed protocol by several numerical test cases as well as a whole design procedure carried out on an aeronautic turbine disk.

Comparison of shape representation methods for dynamic cell analysis

To evaluate the performance of basic shape representation methods for the description of dynamic cellular morphology, several frequently-used shape descriptors are compared. The methods are examined by using 50 lymphocyte video clips including two kinds of lymphocyte cells. Our goal is to represent cell shape in each frame accurately, meanwhile precisely classify the two groups of cells based on the cellular morphological variations in the video clips. Experimental results illustrate that in general the region-based shape descriptors outperform the contour-based ones, since the contourbased methods are excessively sensitive and ignorant to cellular internal information. Due to their robustness to noise, the region-based shape descriptors are suitable for dynamic cell representation. Although region-based methods are more time-consuming, they analyze the entire cell area.

Electrochemical Properties of Electrodes with Different Shapes and Diffusion Kinetic Analysis of Microbial Fuel Cells on Ocean Floor

Microbial fuel cell(MFC) on the ocean floor is a kind of novel energy-harvesting device that can be developed to drive small instruments to work continuously.The shape of electrode has a great effect on the performance of the MFC.In this paper,several shapes of electrode and cell structure were designed,and their performance in MFC were compared in pairs:Mesh(cell-1) vs.flat plate(cell-2),branch(cell-3) vs.cylinder(cell-4),and forest(cell-5) vs.disk(cell-6) FC.Our results showed that the maximum power densities were 16.50,14.20,19.30,15.00,14.64,and 9.95 mWm-2 for cell-1,2,3,4,5 and 6 respectively.And the corre-sponding diffusion-limited currents were 7.16,2.80,18.86,10.50,18.00,and 6.900 mA.The mesh and branch anodes showed higher power densities and much higher diffusion-limited currents than the flat plate and the cylinder anodes respectively due to the low diffusion hindrance with the former anodes.The forest cathode improved by 47% of the power density and by 161% of diffusion-limited current than the disk cathode due to the former's extended solid/liquid/gas three-phase boundary.These results indicated that the shape of electrode is a major parameter that determining the diffusion-limited current of an MFC,and the differences in the elec-trode shape lead to the differences in cell performance.These results would be useful for MFC structure design in practical applica-tions.

Effects of Storage Duration and Temperature of Human Plasma and Serum on Red Blood Cell Aggregation and Shape

Platelet-free plasma of human blood (sodium citrate and EDTA as an anticoagulant) and serum were stored at 4°C, room temperature (25°C) and at 37°C for 24 hours. RBC aggregation decreased after incubation of plasma and serum at 37°C for 4 hours. The RBC shape was changed at the same time: discocytes transformed to echinocytes. Storage of plasma and serum at 4°C and room temperature did not lead to significant alterations of RBC aggregation. The RBC shape did not change in influence of such plasma and serum. The most considerable decrease of RBC aggregation and change of their shapes were observed in the plasma and serum incubated at 37°C for 24 hours. Dilution of incubated plasma by fresh plasma led to consistent restoration of erythrocyte shape and their aggregation.

Influence of matrigel on the shape and dynamics of cancer cells

The interaction between extracellular matrices and cancer cells plays an important role in regulating cancer cell behaviors. In this article, we use matrigel to mimic extracellular matrices and investigate experimentally how matrigel influences the shape and dynamics of breast cancer cells(MDA-MB-231-GFP cells). We find that matrigel facilitates cancer cells' migration and shape deformation. The influences of the matrigel concentration are also reported.

Shape formation of closed-cell aluminum foam in solid–liquid–gas coexisting state

The mold pressing process was applied to investigate the formability of closed-cell aluminum foam in solid–liquid–gas coexisting state.Results show that the shape formation of closed-cell aluminum foam in the solid–liquid–gas coexisting state was realized through cell wall deformation and cell movement caused by primary α-Al grains that slid,rotated,deformed,and ripened within cell walls.During formation,characteristic parameters of closed-cell aluminum foam were almost unchanged.Under proper forming conditions,shaped products of closed-cell aluminum foam could be fabricated through mold pressing.

Unusual W-shaped Galvanic Cell Model of ISCC of α-brass in Neutral Mattsson's Solution

Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual 'W'-shaped galvanic cell whose cathode is the grain boundary oxide film (G.B.0. film) and surface film and the anode is fresh metal at the cracked tip on both sides of the G.B.0. film. Redox reactions involved in the cell have been proposed here. According to this mdel, initidtion of ISCC is caused by the rupturing of surface film along grain boundaries, thus forming a galvanic cell. Propagation of ISCC resulted from alternate advances of G.B.0. film and dissolution on both sides of G.B.0. film caused by the effect of electrochemical reaction. This work developed an effective approach to investigate the embrittlement process at the tip of the crack, by increasing the length of the embrittlement region through constant strain test and distinguishing the morphology and the nature of the corrosion products by optical microscopy and scanning electron microscopy (SEH).

Carrier transport via V-shaped pits in InGaN/GaN MQW solar cells

Carrier transport via the V-shaped pits （V-pits） in InGaN/GaN multiple-quantum-well （MQW） solar cells is numer- ically investigated. By simulations, it is found that the V-pits can act as effective escape paths for the photo-generated carriers. Due to the thin barrier thickness and low indium composition of the MQW on V-pit sidewall, the carriers entered the sidewall QWs can easily escape and contribute to the photocurrent. This forms a parallel escape route for the carries generated in the fiat quantum wells. As the barrier thickness of the fiat MQW increases, more carriers would transport via the V-pits. Furthermore, it is found that the V-pits may reduce the recombination losses of carriers due to their screening effect to the dislocations. These discoveries are not only helpful for understanding the carrier transport mechanism in the InGaN/GaN MQW, but also important in design of the structure of solar cells.

Cell adhesion molecules regulate contractile ring-indepen- dent cytokinesis in Dictyostelium discoideum

To investigate the roles of substrate adhesion in cytokinesis, we established cell lines lacking paxillin （PAXB） or vineulin （VINA）, and those expressing the respective GFP fusion proteins in Dictyostelium discoideum. As in mammalian cells, GFP-PAXB and GFP-VINA formed focal adhesion-like complexes on the cell bottom, paxB^- cells in suspension grew normally, but on substrates, often failed to divide after regression of the furrow. The efficient cytokinesis of paxB^- cells in suspension is not because of shear forces to assist abscission, as they divided normally in static suspension culture as well. Double knockout strains lacking mhcA, which codes for myosin II, and paxB or vinA displayed more severe cytokinetic defects than each single knockout strain. In mitotic wild-type cells, GFP-PAXB was diffusely distributed on the basal membrane, hut was strikingly condensed along the polar edges in mitotic mhcA^- cells. These results are consistent with our idea that Dictyostelium displays two forms of cytokinesis, one that is contractile ringdependent and adhesion-independent, and the other that is contractile ring-independent and adhesion-dependent, and that the latter requires PAXB and VINA. Furthermore, thatpaxB- cells fail to divide normally in the presence of substrate adhesion suggests that this adhesion molecule may play additional signaling roles.

GTEM Cell斧形过渡块侧边曲线方程的算法

为便于加工 ,以往的吉赫兹横电磁波传输室 (GTEMCell)过渡接头中斧形过渡块均采用近似设计 ,即侧边取直线。这样做的结果是传输损耗曲线在过渡段的分布不理想。基于修正的目的 。

Sequence Pair-Based Scatter Search Approach for Cell Formation and Layout Considering Unequal Machine Dimensions and Cell Input and Output Locations

In the purpose of dealing with the inconsistency of the machine dimensions in cell formation and layout problems,comprehensively taking into account such factors as alternative process routings, lot splitting, cell input and output( I / O)locations,an integrated cell formation and layout model considering unequal machine dimensions is established which aims at minimizing intra-cell material handling cost,inter-cell material handling cost and cell expansion cost. A sequence pair-based scatter search algorithm is proposed which simultaneously adopts the roulette wheel selection operator as a subsets combination method to improve the quality of new solutions and the dynamic reference sets updating method to accelerate the convergence rate. Through the comparison of the results achieved by the proposed algorithm, Lingo and simulated annealing under different problem scales,the correctness of the model and the effectiveness of the algorithm are verified.

腹膜后伴有奇异形细胞的Castleman病1例

目的:探讨腹膜后伴有奇异形细胞的Castleman病临床特点、病理特征、鉴别诊断,减少误诊。方法:对我院收治的腹膜后伴有奇异形细胞的Castleman病1例的临床资料进行回顾性分析并文献复习。结果:患者因腹部胀满不适半年余就诊。行CT检查提示腹膜后巨大肿块,考虑脂肪肉瘤遂行腹膜后肿瘤切除术。术后病理检查示淋巴滤泡数量增多,套区增宽,生发中心萎缩,滤泡间可见大量的浆细胞及少量淋巴细胞的背景中可见散在奇异形大细胞;免疫组织化学染色示:CD3、CD5、CD38、CD20及CD21均(+),CyClinD1(-),Kappa、Lambda均示部分(+)。确诊为腹膜后Castleman病,术后恢复良好出院。随访9个月未见明显复发征象。结论:伴有奇异形细胞的Castleman病较为罕见,对奇异形细胞认识不足,易误诊为恶性肿瘤,导致过度治疗。其体征及影像学检查缺乏特异性,及时行组织病理学检查是避免误诊的关键。

330 kA铝电解槽异形阴极碳块对水平电流的影响

采用有限元仿真计算,对330 kA铝电解槽传统阴极碳块结构和异形阴极碳块结构的电场进行仿真模拟,主要对铝液中水平电流分布进行分析。研究发现,异形阴极碳块结构相对于传统阴极碳块结构能够在影响压降较小的前提下降低水平电流密度。模拟结果表明,在异形阴极碳块表面凸起中增加隔断并改变凸起角度,对降低铝液中水平电流效果明显,能够降低铝液中最大水平电流密度27.8%,平均水平电流密度34.3%,有效提升了铝电解槽电流效率。

基于ANSYS的SMA复合材料双闭室梁动力响应分析

将形状记忆合金(shape memory alloy,SMA)层与玻/碳纤维混杂复合材料双闭室复合材料梁相粘合,利用SMA的超弹性效应对复合材料梁进行振动被动控制。利用有限元软件ANSYS对悬臂式复合材料梁进行动力响应分析,分别研究了自由端作用有脉冲荷载及上表面作用有简谐压力两种情况下梁自由端的位移响应,分析了SMA对梁的振动抑制效果,并讨论了SMA铺设位置、铺设长度以及铺设厚度对该复合材料梁振动抑制效果的影响。结果表明,由于SMA超弹性耗散能量的特性,双闭室复合材料梁的振动得到了一定程度的抑制。而且,SMA铺设在梁的上下表面比铺设在左右腹板具有更好的减振效果。此外,在梁的上下表面只粘贴距离固定端1/4长度的SMA层对梁的振动抑制效果等同甚至优于沿全长粘贴SMA层的振动抑制效果;脉冲载荷作用下,SMA层的厚度越大,其对复合材料梁的振动抑制效果越好。

高铁转向架焊接接头内部裂纹应力强度因子研究

通过改变高铁转向架常用的十字焊接接头和斜交焊接接头中半椭圆形表面裂纹和椭圆形埋藏裂纹的大小、形状比和深度等几何参数,利用围线积分法探究裂纹前缘Ⅰ型应力强度因子K_(Ⅰ)受几何参数的影响规律,并利用多元非线性回归的方法拟合出了求解K_(Ⅰ)的数学表达式,利用围线积分法分析了K_(Ⅰ)对裂纹大小和形状比变化的敏感程度。结果表明,K_(Ⅰ)随裂纹的增大而增大并根据接头和裂纹形式的不同逐渐发散或收敛;K_(Ⅰ)随裂纹形状比的增大而减小并逐渐收敛;K_(Ⅰ)最大值点的位置由裂纹大小、裂纹形状比和裂纹位置共同决定;拟合出的求解K_(Ⅰ)的数学表达式误差在5%以内,精度较高;在四种裂纹形式中,十字接头表面裂纹K_(Ⅰ)对裂纹形状比的敏感度明显低于其他三种裂纹形式,斜交接头埋藏裂纹对裂纹大小的敏感度明显高于其他三种裂纹形式。

阳极支撑型锥管串接式直接碳固体氧化物燃料电池组的制备及性能

针对阳极支撑型直接碳固体氧化物燃料电池(DC-SOFC)的浓差极化阻抗大的问题,本研究采用改进后的凝胶注模法制备了阳极支撑型锥管状固体氧化物燃料电池(SOFC)。通过适当增加溶剂的含量,改善了浆料的流动性,提高了成品的质量;通过增大造孔剂的含量,提高了阳极的孔隙率,减小了气体的扩散阻力。改进后的SOFC以氢气为燃料,在800℃运行时,开路电压为1.05 V,电化学阻抗谱的极化阻抗更小,电池的最大功率密度为0.67 W×cm^(–2)(阴极有效面积为2.2 cm^(2)),明显优于改进前的SOFC。改进后的SOFC直接采用担载质量分数5%K的活性炭为燃料,在800℃运行时,开路电压为1.030 V,接近理论电压,最大功率密度达0.74 W×cm^(–2),以400 mA进行恒流放电,碳燃料的有效利用率为31%,高于改进前电池的碳燃料的有效利用率17%。将改进后的4个锥管状单电池串联成电池组,直接采用担载质量分数5%K催化剂的活性炭为燃料,在800℃运行时,最大功率达8.0 W,高于改进前的4节DC-SOFC电池组(4.1 W),该电池组碳燃料的有效利用率为15%,峰值功率密度可达0.91 W×cm^(–2),超过了文献报道的最高值。

提取方法对柿多糖提取率及生物活性的影响

分别以水、草酸(质量分数为1.8%)、氢氧化钠(0.2 mol/L)作浸提剂,用热水、微波(中火,6 min)、超声波(600 W,15 min)和反复冻融法提取柿子粗多糖,对不同提取方法获得的多糖进行纯化、测多糖得率、观察细胞形态变化,进行抗氧化、抗菌性比较。结果表明:不同提取剂和提取方法对于植物细胞的形态都有不同程度的破坏,反复冻融细胞破碎最彻底,微波提取所得多糖含量最高。不同提取剂和提取方法获得的柿多糖在抗氧化和抗菌方面表现出较大差异,说明提取的过程与其生物学效能密切相关。

显微细胞图像分析方法的研究进展

阐述了图像处理技术在显微细胞图像处理领域的发展现状,包括显微细胞图像预处理算法、细胞分割算法、细胞跟踪算法、细胞形状变化分析、3D细胞图像分析等内容.指出了显微细胞图像处理研究中的难点,如非刚体形状的描述,旋转、平移、尺度变化对形状描述影响的消除,3D形状信息的提取和压缩等.并探讨了显微细胞图像处理由静态图像分析向动态图像分析,由2D图像分析向3D图像分析,由定性分析向定量分析的发展趋势.

肾组织肥大细胞的形态学特点及染色方法

目的 探索检测肾组织肥大细胞的理想方法 ,研究肾组织中肥大细胞的分布和形态特点。方法 用免疫组织化学方法和 4种不同pH值的甲苯胺蓝染液对 4 6例肾小球肾炎患者肾活检标本进行染色 ,观察肥大细胞在不同时间点的染出数及分布、形态特点 ,比较几种方法肥大细胞的显示数 ,并与免疫组织化学结果对照 ,计算每种染液的染出率。同时用透射电镜进一步观察肥大细胞的形态及超微结构。结果 肥大细胞数量比较 :pH 0 5与 1 0组无差别 ,其余的两两比较差异都有显著性 ,几种染液显示的肥大细胞相对于免疫组化结果的染出率分别是 78 8% (pH 0 5 ) ,79 4 % (pH 1 0 ) ,5 6 9% (pH 3 0 ) ,10 2 % (pH 5 0 )。电镜观察到幼稚、成熟和脱颗粒的形态不一的肥大细胞。 结论 ①免疫组织化学染色效果最好 ,其次是 pH值 0 5和 1 0的甲苯胺蓝染液 ,pH 5 0染液的效果最差。②肾组织肥大细胞形态多样 。