Oscillatory sensitivity patterns for global modes in wakes

Globally unstable wakes with co-flow at intermediate Reynolds numbers are studied, to quantify important spatial regions for the development and control of the global instability. One region of high structural sensitivity is found close to the inlet for all wakes, in agreement with previous findings for cylinder wakes. A second, elongated region of high structural sensitivity is seen downstream of the first one for unconfined wakes at Re = 400. When base flow modifications are considered, a spatially oscillating sensitivity pattern is found inside the downstream high structural sensitivity region. This implies that the same change in the base flow can either destabilize or stabilize the flow, depending on the exact position where it is applied. It is shown that the sensitivity pattern remains unchanged for different choices of streamwise boundary conditions and numerical resolution. Actual base flow modifications are applied in selected configurations, and the linear global modes recomputed. It is confirmed that the linear global eigenvalues move according to the predicted sensitivity pattern for small amplitude base flow modifications, for which the theory applies. We also look at the implications of a small control cylinder on the flow. Only the upstream high sensitivity region proves to be robust in terms of control, but one should be careful not to disturb the flow in the downstream high sensitivity region, in order to achieve control. The findings can have direct implications on the numerical resolution requirements for wakes at higher Reynolds numbers. Furthermore, they provide one more possible explanation to why confined wakes have a more narrow frequency spectrum than unconfined wakes.

The retrieval of structured design rationale for the re-use of design knowledge with an integrated representation

Design knowledge can be acquired from various sources and generally requires an integrated representation for its effective and efficient re-use. Though knowledge about products and processes can illustrate the solutions created (know-what) and the courses of actions (know-how) involved in their creation, the reasoning process (know-why) underlying the solutions and actions is still needed for an integrated representation of design knowledge. Design rationale is an effective way of capturing that missing part, since it records the issues addressed, the options considered, and the arguments used when specific design solutions are created and evaluated. Apart from the need for an integrated representation, effective retrieval methods are also of great importance for the re-use of design knowledge, as the knowledge involved in designing complex products can be huge. Developing methods for the retrieval of design rationale is very useful as part of the effective management of design knowledge, for the following reasons. Firstly, design engineers tend to want to consider issues and solutions before looking at solid models or process specifications in detail. Secondly, design rationale is mainly described using text, which often embodies much relevant design knowledge. Last but not least, design rationale is generally captured by identifying elements and their dependencies, i.e. in a structured way which opens the opportunity for going beyond simple keyword-based searching. In this paper, the management of design rationale for the re-use of design knowledge is presented. The retrieval of design rationale records in particular is discussed in detail. As evidenced in the development and evaluation, the methods proposed are useful for the re-use of design knowledge and can be generalised to be used for the retrieval of other kinds of structured design knowledge. © 2012 Elsevier Ltd. All rights reserved.

Robust multiplexed MPC for distributed multi-agent systems

This paper extends the authors' earlier work which adapted robust multiplexed MPC for application to distributed control of multi-agent systems with non-interacting dynamics and coupled constraint sets in the presence of persistent unknown, but bounded disturbances. Specifically, we propose exploiting the single agent update nature of the multiplexed approach, and fix the update sequence to enable input move-blocking and increased discretisation rates. This permits a higher rate of individual policy update to be achieved, whilst incurring no additional computational cost in the corresponding optimal control problems to be solved. A disturbance feedback policy is included between updates to facilitate finding feasible solutions. The new formulation inherits the property of rapid response to disturbances from multiplexing the control and numerical results show that fixing the update sequence does not incur any loss in performance. © 2011 IFAC.

集胞藻PCC6803中ORF sll0260对于维持基本生命活动的必要作用

集胞藻(Synechocystis sp.)6803的未知功能基因中有很多是细胞的基本生命活动所需要的,这些基因插入失活往往会导致细胞死亡,因而得不到分离完全的突变株,难以进行遗传学研究。构建突变株以铜离子调控的启动子PpetE来控制此类未知功能基因的表达则可能获得完全分离。构建PpetE-sll0260突变株并对sll0260必要作用进行研究。在完全分离的突变株中,去除铜离子可关闭sll0260的表达。此时,突变株生长受到严重抑制,色素含量大为降低,类囊体膜结构破坏,光合作用消失,呼吸能力下降。这些结果

红色伪角毛虫的形态学重描述及与相近种的比较(纤毛门,腹毛目)

利用活体观察、蛋白银染色技术对1种海水腹毛目纤毛虫—红色伪角毛虫Pseudokeronopsis rubra的青岛种群之活体形态和纤毛图式做了研究。其特征如下:虫体呈长带状,尾钝圆,身体柔软,高度可曲;皮层颗粒棕黄色,主要呈玫瑰花形分布,其余散布;表膜下具另1种无色、双面凹形颗粒。口围带小膜数为48～55;左、右缘棘毛各1列,中腹棘毛排成典型的锯齿状并延伸至横棘毛附近;额棘毛无明确分化,呈冠状排布并与中腹棘毛列相连续;口棘毛1根,额前棘毛2根;背触毛4列。大核90～140枚。伸缩泡位于体后左侧1/3处。经

Boundary effects on the vibration statistics of a random plate

This paper considers the estimation of statistics of displacement of a vibrating rectangular plate with random wave scatterers. The influence of uncertainty is investigated using point impedance theory. Coherent boundary effects are seen, which decrease when the number of scatterers increases. The boundary effect is investigated using images and the first side and corner reflections are found to be a minimum requirement to estimate the spatial correlation. Statistics for point driven response are investigated under the assumption that the statistics of the natural frequencies follow those of the Gaussian Orthogonal Ensemble (GOE). The estimates are compared with Monte Carlo simulation results, and they show good agreement. © 2012 Elsevier Ltd. All rights reserved.

碱度增加对蛋白核小球藻光合活性与胞外多糖的影响

本文研究了不同重碳酸盐(HCO_3~-)碱度2.3mmol/L(ALK2.3)和12.4mmol/L(ALK12.4)条件对蛋白核小球藻光合活性、色素组成、丙二醛(MDA)含量与胞外多糖的影响.实验结果表明,碱度增加对蛋白核小球藻光合活性呈促进-抑制-促进效应,ALK2.3对光合活性影响的强度高于ALK12.4.碱度增加提高叶绿素b/叶绿素a(Chl.b/Chl.a)的值,降低类胡萝卜素/叶绿素(Caro/TChl)的值,并且ALK12.4条件下对藻细胞的作用程度强于ALK2.3.此外碱度增加刺激蛋白核小

念珠藻葛仙米生理生化特性对不同低温胁迫的响应

研究了不同培养温度下对念珠藻葛仙米的生长和相关生理生化特性的变化。结果表明,低温抑制葛仙米的生长,在2℃~5℃低温下其生长甚至完全停止;在10℃低温胁迫下,其生长延滞期变长,其后仍能保持正常生长。低温胁迫下,葛仙米光合系统II(PSII)的光合效率(Fv/Fm)的变化趋势与生长曲线相似;细胞电解质渗透率在低温胁迫初期尚能保持比较低的水平,但随着时间延长而升高;可溶性糖和还原性糖含量的变化则随胁迫加剧有不同程度升高。可溶性蛋白含量则在低温下保持比较低的水平。这些结果表明,低温对葛仙米的生长和光合作用具有抑制