Stabilization of polymer bilayers by introducing crosslinking at the interface

Bisphenol A solid epoxy serves as an effective reaction compatibilizer to the bisphenol A polycarbonate (PC)/PMMA bilayer systems. Addition of epoxy to the bottom PMMA layer can retard or even prevent the dewetting of PC films by introducing crosslinking between both components at the interface. This is the first investigation of polymer bilayers stabilized by chemical reactions.

Synthesis using electrospinning and stabilization of single layer macroporous films and fibrous networks of poly(vinyl alcohol)

We demonstrated in this paper an electrospinning technique could be employed to prepare the single layer macroporous films and fibrous networks of poly(vinyl alcohol) (PVA). A crucial element using electrospinning on the development of these electrospun structures was to shorten the distance of from the needle tip to the collector (L), which resulted in the bond of the wet fibers deposited on the collector at the junctions. The morphologies and average pore size of electrospun structures of PVA were mainly predominated by L and the time of collecting wet fibers on the collector. In addition, experimental results showed that an increase of the PVA concentration or a decrease of the applied voltage could also diminish slightly the average pore size of electrospun productions. Furthermore, a 60 degrees C absolute ethanol soak to PVA electrospun production led them to be able to stabilize in water for 1 month against disintegration. Differential scanning calorimetry (DSC) demonstrated that the 60 degrees C ethanol soak enhanced the degree of crystallinity of PVA production. The structural characteristic of macroporous films and networks in combination with their easy processability suggests potential utility in issue engineering applications.

The stabilization effect of glutaraldehyde on the Spirulina plateusis phycobilisomes

The spectral properties of the glutaraldehyde-treated phycobilisomes were studied. The results showed that glutaraldehyde was effective in preventing phycobilisomes from dilution-induced dissociation and preserving the intra-phycobilisomes energy transfer.

Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes

Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide. Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.

移动机器人数学模型的近似线性化

针对机器人控制领域中一类多输入多输出(MIMO)仿射非线性系统,提出了一种基于平衡流形的近似线性化状态反馈镇定算法,并用此算法解决了一类完整约束轮式移动机器人(WMR)的镇定问题.仿真分析表明,此方法不仅能够实现系统的镇定,而且降低了因平衡工作点变动给系统稳定性带来的影响,同时也大大地简化了对非线性系统的综合设计过程,具有良好的控制效果和实用性.

Stabilization of Dynamic Systems for Multiple Omni-Directional Mobile Robots

本文考虑了由2个全方位移动机器人组成的混合动力学系统的协调拟镇定问题.利用机器人位置之间的向量与机器人目标之间向量的内积,设计了多步拟镇定律,该控制律能够在避碰后按指数速率运动到目标点,且在整个过程中两机器人之间的距离不小于避碰的安全距离.最后对2个全方位移动机器人进行了仿真,验证了所给方法的有效性。

Stabilization of Uncertain Nonholonomic Dynamic Systems with Bounded Inputs

The sliding mode approach and the multi-step control strategy are exploited to propose a stabilizing controller for uncertain nonholonomic dynamic systems with bounded inputs. This controller can stabilize the system to an arbitrarily small neighborhood about its equilibrium in a finite time .Its application to a nonholonomic wheeled mobile robot is described. Simulation result shows that the proposed controller is effective

最优控制具有非完整性的两轮驱动机器人小车

研究了移动机器人反馈控制问题．这里所考虑的机器人是一个两轮驱动的具有非完整性的移动机器人小车．考虑了笛卡儿空间中轨线跟踪问题的扩展．且表明只要参考小车保持运动，在虚设的参考小车位形周围的小车位形的稳定成为可能．提出了最优控制律并给出了仿真结果。

Public feedback - but personal feedforward?

Academic feedback is taken here as the reporting to student writers of the strengths and weaknesses of their submitted draft work, while academic feedforward refers to constructive advice regarding possible strengthening of students’ next work. Both originate from a tutor’s initial judgement of a student’s work. Feedback and feedforward on work showing need for improvement are problematic in a Confucian Heritage Culture. Even gently constructive advice within a programme seeking evidence for assessment of critical thinking may lead to perception of hurtful criticism by Taiwanese students. Some could withdraw from class activity accordingly. So the writers adjusted their response style. They now choose between different approaches featuring tutorial feedback or feedforward, depending on the standard of work being judged. When individual postings feature poor critical thinking, the writers opt for private messages concentrating on constructive feedforward. For better postings, they provide positive feedback with reasons for their judgements, and summarise to the class these exemplars of generic strengths in critical thinking. They also offer private prompting when they see scope for further enrichment of an able student’s critical thinking. This might also be a useful practice when tutoring solely in the West. (192 words) Keywords: Confucian Heritage Culture, public feedback, private feedforward, assessment

Feedback Unbound: from master to usher.

A major theme of this book is that feedback should encourage dialogue; between students and lecturers, amongst peers and individually, as a form of self-critique and reflection. Here we endorse that theme but also propose an understanding of dialogue that goes beyond simple exchang or the presence of two or more voices. Inspired by Freire’s (1996) critical pedagogy we seek to make a link between the social nature of learning, the social nature of dialogue and the role of feedback as dialogue in a broader transformative learning process, and not merely as an adjunct to assessment.

Marking and providing feedback face-to-face: staff and student perspectives.

The setting, marking and providing feedback on assessments forms an important part of a tutor’s role. Studies into the use of feedback and how it is interpreted by students indicate a mismatch between what students are looking for and what tutors think they are giving. Tutors comment that students are more interested in the mark than the feedback, and yet students indicate that they do not get enough feedback, or that it is not useful. This study investigates student and staff perceptions of the linking of marking and feedback in face-to-face sessions. A cohort of year one university students were given the option of receiving either written feedback or a 15 minute meeting with one of their tutors to have their essay marked with them. Forty nine students chose face-to-face marking, the remaining 35 students received written feedback. Focus groups were used to investigate the student experience. Staff members were also asked to reflect on the process. Students and staff found the experience of face-to-face marking beneficial and positive. Both felt that the time spent together allowed for a feedback dialogue about the piece of work, and that staff could explain and justify why marks were given.

Hamilton?Jacobi?Bellman equations for quantum optimal feedback control

Gough, John; Belavkin, V.P.; Smolianov, O.G., (2005) 'Hamilton?Jacobi?Bellman equations for quantum optimal feedback control', Journal of Optics B: Quantum and Semiclassical Optics 7 pp.S237-S244 RAE2008

The Specialized Mappings Architecture

A probabilistic, nonlinear supervised learning model is proposed: the Specialized Mappings Architecture (SMA). The SMA employs a set of several forward mapping functions that are estimated automatically from training data. Each specialized function maps certain domains of the input space (e.g., image features) onto the output space (e.g., articulated body parameters). The SMA can model ambiguous, one-to-many mappings that may yield multiple valid output hypotheses. Once learned, the mapping functions generate a set of output hypotheses for a given input via a statistical inference procedure. The SMA inference procedure incorporates an inverse mapping or feedback function in evaluating the likelihood of each of the hypothesis. Possible feedback functions include computer graphics rendering routines that can generate images for given hypotheses. The SMA employs a variant of the Expectation-Maximization algorithm for simultaneous learning of the specialized domains along with the mapping functions, and approximate strategies for inference. The framework is demonstrated in a computer vision system that can estimate the articulated pose parameters of a human’s body or hands, given silhouettes from a single image. The accuracy and stability of the SMA are also tested using synthetic images of human bodies and hands, where ground truth is known.