Differences between beginning and advanced design students in analogical reasoning during idea generation: evidence from eye movements

Cognition, Technology & Work - In existing studies about analogical reasoning during idea generation in design, there is lack in quantitative and objective evidences showing the relationship...     

An internal combustion engine platform for increased thermal efficiency,constant‐volume combustion,variable compression ratio,and cold start

An internal‐combustion engine platform, which may operate on a portfolio of cycles for an increased expansion ratio, combustion under constant volume, variable compression ratio, and cold start, is introduced. Through unique thermodynamic cycles, the engine may be able to operate on a much greater expansion ratio than the compression ratio for a significantly improved thermal efficiency. This improvement is attained without involving a complex mechanical structure or enlarged engine size, and at the same time without reducing the compression ratio. The engine with these features may serve as an alternative to the Atkinson cycle engine or the Miller cycle engine. Furthermore, based on the same engine platform, the engine may operate on other cycles according to the load conditions and environmental considerations. These cycles include those for combustion under constant volume, variable compression ratio under part load conditions, and cold start for alternative fuels. It is believed that the introduced thermodynamic cycles associated with the engine platform may enable a future internal combustion engine that could generally increase the thermal efficiency by about 20% under full and part load conditions and overcome the cold start problem associated with diesel fuels or alternative fuels such as ethanol and methanol. Copyright © 2011 John Wiley & Sons, Ltd.     

发动机制造企业的成本控制与SAP

发动机因其开发周期长,科技含量高,材料材质、工艺路线复杂、环保要求高等原因,而成为高成本的制造行业。因此,有效的成本控制已是发动机制造企业在激烈的市场竞争中成败的关键。SAP系统因其数据集成性、资源共享性、传输及时性等特点,摈弃了以往发动机制造企业传统成本管控中的数据多源、信息屏蔽、权限分散等弊端,做到了研发、工艺、生产、物流、财务数据同源、资源共享、责权分担,为柴油机制造企业从产品研发源头就实施有效的成本控制提供了手段,极大地提高了企业成本管控的质量和效益。     

Precipitation of iron-rich intermetallic phases in Al-4.6Cu-0.5Fe-0.5Mn cast alloy

The solidification of Al-4.6Cu-0.5Fe-0.5Mn (206 type) cast alloy has been studied using Thermal Analysis, Differential Scanning Calorimeter, Scanning Electron Microscopy, Electron Back-Scattered Diffraction (EBSD), and Transmission Electron Microscopy (TEM). It is interesting to note that an iron-rich intermetallic phase, Al₃(FeMn), is experimentally observed to be dominantly present in the fully solidified cast structure of the experimental 206 cast alloy, in addition to β-Fe (Al₇Cu₂(FeMn)/Al₇Cu₂Fe) phase. Al₃(FeMn) phase is formed through a eutectic reaction approximately at 640 °C during solidification, possibly resulting from the phase selection and segregation of Fe in liquid Al. The presence of the Al₃(FeMn) phase has been confirmed by both EBSD and TEM. It is also found that both β-Fe and Al₆(FeMn) are possible to nucleate on Al₃(FeMn), as confirmed by the calculated low planar disregistries. The possible solidification reactions have been established for 206-type cast alloy at 0.5%Fe.     

The influence of simulation time-resolution on the matching between on-site micro-wind generation and building electric demand

This paper is to investigate the unique impact of simulation time-resolutions on energy matching between on-site micro-wind turbine and household electric demand. The focused indices are on-site electrical energy fraction (OEFe), on-site electrical energy matching (OEMe), and their errors (e_OEF and e_OEM). The methodology consists of parametric analyses with respect to time-resolution levels, averaging methods, demand profiles, turbine capacities, and wind conditions. Two averaging methods are used: ‘Speed Averaging’ and ‘Power Averaging’. With a coarser resolution, two averaging effects have been found. One is an overestimation effect by both the averaging methods, which are more likely to be encountered especially when a high-resolution generation curve frequently crosses intermittent long spikes of a demand curve. The other effect is an underestimation effect on OEFe simultaneously occurring with the Speed Averaging Method under the conditions of (1) a low wind speed and (2) a high unstable wind speed and a low turbine capacity.     

Application of Air-Assisted Liquid-Liquid Microextraction for Determination of Some Fluoroquinolones in Milk Powder and Egg Samples: Comparison with Conventional Dispersive Liquid-Liquid Microextraction

Herein, an air-assisted liquid-liquid microextraction (AALLME) has been described and compared to conventional dispersive liquid-liquid microextraction (DLLME) for the extraction/preconcentration of six fluoroquinolone compounds in milk powder and egg samples prior to high-performance liquid chromatography-UV detection (HPLC-UV). In order to compare the novel AALLME technique to the conventional DLLME technique, several parameters that influence the extraction efficiency were studied and optimized. Both methods have been validated for milk powder and egg analysis, obtaining limits of quantification lower than those usually permitted by legislation in food matrices, with precisions expressed as coefficients of variation lower than 8 % and recoveries between 72 and 115 % which were acceptable recoveries and repeatability. An AALLME method needs less organic solvent and shorter centrifugation time; therefore, it is more environmentally friendly and efficiently compared to DLLME.     

Effect of joint gap on the quality of laser beam welded near-β Ti-5553 alloy with the addition of Ti–6Al–4V filler wire

Ti–5Al–5V–5Mo–3Cr (Ti-5553) sheets were welded using a Nd: YAG laser system and Ti–6Al–4V filler wire. The effect of joint gap on weld geometry, defects, microstructure, and hardness was investigated. Fully penetrated welds up to a joint gap of 0.5 mm were produced. The two main defects observed were porosity and underfill. The addition of filler wire reduced underfill but increased porosity, especially at large joint gaps. The fusion zone (FZ) microstructure at low joint gaps consisted of retained β with a dendritic morphology. At a joint gap of 0.3 mm, regions of orthorhombic α″ martensite were observed in the weld zone which increased in proportion as the joint gap increased from a volume percentage of 4.9% at 0.3 mm to a volume percentage of 44% at 0.5 mm. Despite the differences in microstructure with increasing joint gap, the FZ hardness remained relatively constant for all joint gaps evaluated.     

Extraction of europium and electrodeposition of Al–Li–Eu alloy from Eu2O3 assisted by AlCl3 in LiCl–KCl melt

The work presents an electrochemical study on preparation of Al–Li–Eu alloys on a tungsten electrode in molten LiCl–KCl–AlCl₃–Eu₂O₃ system at 753 K and 953 K. Gibbs energy shows that AlCl₃ can chloridize Eu₂O₃, with a discharge in the form of Eu(III) ions on the cathode. The electrochemical behavior of Al(III), Li(I) and Eu(III) and alloy formation processes were investigated by cyclic voltammetry, square wave voltammetry, and chronopotentiometry. Cyclic voltammetry indicated that the underpotential deposition of europium on pre-deposited Al forms two Al–Eu intermetallic compounds at electrode potentials around ?2.00 V and ?2.34 V, respectively. And the underpotential deposition of lithium on Al surface at about ?2.24 V leads to a formation of Al–Li alloy. X-ray diffraction (XRD) indicated that Al–Li–Eu alloys with different phases were obtained via galvanostatic electrolysis. The microstructure and micro-zone chemical analysis of Al–Li–Eu alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively. The analysis of EDS showed that element Eu mainly distributes on needle-like precipitate, and not homogeneously in the Al–Li–Eu alloy. Composition of the alloys was analyzed by inductive coupled plasma analysis, and current efficiency was also determined with respect to the alloy composition.