Learning task models in ill-defined domain using an hybrid knowledge discovery framework

Domain experts should provide Intelligent Tutoring Systems (ITS) with relevant domain knowledge that enable it to guide the learner during problem-solving learning activities. However, for ill-defined domains this knowledge is hard to define explicitly. Our hypothesis is that knowledge discovery (KD) techniques can be used to extract problem-solving task models from the recorded usage of expert, intermediate and novice learners. This paper proposes a procedural-knowledge acquisition framework based on a combination of sequential pattern mining and association rules discovery techniques. The framework has been implemented and is used to discover new meta-knowledge and rules in a given domain which then extend domain knowledge and serve as problem space, allowing the Intelligent Tutoring System to guide learners in problem-solving situations. Preliminary experiments have been conducted using the framework as an alternative to a path-planning problem solver in CanadarmTutor.     

Affective and cognitive design for mass personalization: status and prospect

The prevailing practice of design for mass customization manifests itself through a configure-to-order paradigm, which means to satisfy explicit customer needs (CNs) and built upon legacy design. With pervasive connectivity and interactivity of the Internet and sensor networks, personalization has been witnessed in a number of industry sectors as a promising strategy that makes the market of one a reality. Mass personalization entails a strategy of producing goods and services to satisfy individual customer’s latent needs with values outperforming costs for both customers and producers. This review paper envisions an affective and cognitive design perspective to mass personalization. By exploiting implicit market demand information and revealing latent CNs, mass personalization aspires to assist customers in making better informed decisions, and to the largest extent, to anticipate customer satisfaction and adapt to customer delight. The key dimensions of mass personalization are identified and discussed. By capitalizing on user experience, affective and cognitive design for mass personalization is expected to address individual customer’s latent CNs. The decisions of affective and cognitive design, involving affective and cognitive needs elicitation, affective and cognitive analysis, and affective and cognitive fulfillment, are reviewed with a wide range of interests, including engineering design, human factors and ergonomics, engineering psychology, marketing, and human-computer interaction. Recent trends and future research directions are also speculated to inspire more meaningful research in this area.     

Mass customization design of engineer-to-order products using Benders’ decomposition and bi-level stochastic programming

Leveraging product differentiation and mass production efficiency in mass customization basically entails a configure-to-order paradigm. In the engineer-to-order (ETO) business, however, companies build unique products in response to ‘foreseeable’ customer specifications. The key challenge of ETO mass customization lies in the complexity of accommodating future design changes when customers are involved in customizing design specifications. This paper proposes a two-stage, bi-level stochastic programming framework to tackle ETO mass customization. At the first stage, product platform configuration is integrated with production reconfiguration, which is formulated as a shortest path problem with resource constraints (SPPRC) to optimize production delays within the capabilities of the process platform. Benders’ decomposition algorithm is applied to solve this optimal configuration problem owing to its high computational efficiency. The second stage scrutinizes the optimal configuration resulting from the first stage for scaling optimization of design parameters (DPs) for each module. All DPs are differentiated by standard or customizable DPs. A bi-level stochastic program is implemented to leverage conflicting goals between the producer (leader) and consumer (follower) surpluses. As a result, ETO customization design is anchored with optimal values of standard DPs and optimal value ranges of customizable DPs. A case study of ship engine and power generator ETO design is presented, demonstrating the feasibility and potential of the ETO mass customization framework.     

A study of beam position diagnostics using beam-excited dipole modes in third harmonic superconducting accelerating cavities at a free-electron laser

We investigate the feasibility of beam position diagnostics using higher order mode (HOM) signals excited by an electron beam in the third harmonic 3.9 GHz superconducting accelerating cavities at FLASH. After careful theoretical and experimental assessment of the HOM spectrum, three modal choices have been narrowed down to fulfill different diagnostics requirements. These are localized dipole beam-pipe modes, trapped cavity modes from the fifth dipole band, and propagating modes from the first two dipole bands. These modes are treated with various data analysis techniques: modal identification, direct linear regression (DLR), and singular value decomposition (SVD). Promising options for beam diagnostics are found from all three modal choices. This constitutes the first prediction, subsequently confirmed by experiments, of trapped HOMs in third harmonic cavities, and also the first direct comparison of DLR and SVD in the analysis of HOM-based beam diagnostics.     

Platinum/iridium/carbon: a high-resolution shadowing material for TEM,STM and SEM of biological macromolecular structures

Thin Pt/Ir/C coating films (1.5 nm) show a fine granularity and provide a high structural resolution in the transmission electron microscope (TEM) when applied to freeze-dried biological macromolecules. They keep their structure when exposed to atmospheric conditions, without the need of an additional stabilizing carbon layer, in contrast to conventional high-resolution shadowing materials such as Ta/W and Pt/C. However, the correct ratio of the components has turned out to be crucial. When evaporating Pt/Ir/C from the source electrode in an electron-beam-heated evaporator, the ratio of the three elements changes progressively, and, consequently, the properties of such films depend strongly on the mass that has been pre-evaporated. In this paper we present a quantitative analysis of the composition of Pt/Ir/C films by wavelength-dispersive X-ray analysis (WDX) undertaken in association with TEM experiments. We applied Pt/Ir/C shadowing to two regular biological test specimens, the phage T4 type III polyhead and the HPI-layer of Deinococcus radiodurans. It turns out that Pt/Ir/C films containing at least 25% C are three-dimensionally stable on the freeze-dried macromolecular samples. By the dramatically improved resolution power of the latest scanning electron microscopes (SEM) and the invention of the scanning tunnelling microscope (STM), two new surface-sensitive tools for the investigation of biological macromolecular structures became available. The Pt/Ir/C coating has proved to be well suited for STM and SEM imaging of freeze-dried biological structures because of its good electrical conductivity and its direct three-dimensional stability. We compare STM, SEM and TEM images of freeze-dried and Pt/Ir/C-coated polyheads.     

Cryofixation of vascular endothelium

Cryofixation refers to the immobilization of tissue components by the rapid removal of heat from the specimen, so that the structure is interred and stabilized in a natural embedding medium, namely, frozen (amorphous or microcrystalline) tissue water. Cryofixation is now often used as a complement to the more traditional fixation methods, especially when the cell structure is delicate or dynamic and may be inaccurately preserved by the slow selective action of chemical fixatives. Vascular endothelial cells are specialized for transcellular transport and for the regulation of blood flow and composition. The dynamic and labile subcellular organization of these cells, presumably reflecting these functional specializations, makes them ideal candidates for cryofixation. Several different types of endothelial cells were directly frozen at temperatures below 20 degrees Kelvin by pressing them against a liquid-helium-cooled block. These samples were subsequently processed for structural analysis by freeze-substitution. Detailed rationales, designs, and protocols are described for both freezing and freeze-substitution. Electron micrographs of cryofixed arterial and venous capillaries (rete mirabile of the American eel), iliac vein (rabbit), and cultured endothelium from the iliac vein (human) reveal that the organization of the characteristic intracellular membrane system of endothelial vesicles is qualitatively similar to that seen in chemically fixed endothelium, especially with regard to the interconnection of clusters of individual vesicles to form elaborate networks. The luminal and abluminal networks are not in communication, at least not in static images. Quantitatively, however, most directly frozen endothelial cells have far fewer vesicular profiles than comparable glutaraldehydefixed cells. The differences can be explained by presuming that the rapid action of cryofixation (approximately 1 msec) gives a more accurate picture of the vesicular network because it captures the transient structure of labile or dynamic membranes.     

Overheating in Auckland homes: testing and interventions in full-scale and simulated houses

ABSTRACT

New Zealand dwellings have thermal conditions managed with relatively light regulation. No minimum airtightness standards exist and historical increases in required insulation levels aimed to reduce winter heating energy consumption. A consequence of this policy is an increased potential for overheating in summer. There has been a steady increase in the use of heat pumps, risking heating energy savings being outweighed by cooling energy increases. Internal temperatures and humidity were monitored in the living spaces of three unoccupied, transportable houses over all four seasons of the Auckland climate. The houses are located on the same site and are of identical construction, apart from selected interventions which were tested to explore their potential to mitigate overheating. Results indicate that overheating can be extreme and long lasting. High internal temperatures are very closely connected with solar gains. Internal temperatures reached 32°C in autumn. Roof space temperatures reached 51°C in summertime. Interventions resulted in modest improvements and an airtight construction provided a small thermal benefit. A thermal model for the houses was developed using EnergyPlus and compared with actual measurements and the interventions. Early results point to the further need to reduce solar gain, increase roof-space ventilation and increase mass, where feasible.     

外墙彩色砂浆的泛碱问题

在干混砂浆工业中．泛碱造成水泥基材料褪色而影响美观性的现象是一个大家普遍关心的问题．泛碱是由于盐分沉积在矿物建筑材料如混凝土．砂浆或砖墙的表面引起的．目前．泛碱对于装饰砂浆如彩色抹灰砂浆和瓷砖填缝剂而言依然是一个令人头痛的问题．泛碱通常不会造成砂浆明显的破坏．而主要是影响产品的感官质量．泛碱经常在建筑物投入使用后的很短时间内产生．此时正是工人．建筑师和业主对新建筑物外观质量最关心的时候．特别是当彩色砂浆的颜色较深时．表面形成的白斑会引起对比度强烈的不规则斑痕．