Mechanical and thermal characterization of compression moulded polylactic acid natural fiber composites reinforced with hemp and lyocell fibers

This research evaluates the effects of PLA/PP blend ratio and Lyocell/hemp mixture ratio on the morphology, water absorption, mechanical and thermal properties of PLA‐based composites. The composites were fabricated with 30 mass % hemp using compression moulding. As a reference composites made from PP were also studied. Combining of hemp and Lyocell in PLA composite leads to the reduction of moisture absorption and can improve the impact, tensile, flexural properties when compared with PLA/hemp. Composite based on the PLA/PP blend‐matrix could not improve the tensile and flexural properties compared with PLA/hemp, however; the lighter composite with better impact properties was obtained. The crystallization temperature of the PLA‐PP/hemp increased compared with pure PLA. This result was also confirmed by the SEM micrographs. The moisture absorption of PLA‐PP/hemp was higher than PLA/hemp. Based on theoretical analysis of DMTA data, there was favorable adhesion in all composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40534.     

CFD study of non-premixed swirling burners: Effect of turbulence models

This research investigates a numerical simulation of swirling turbulent non-premixed combustion. The effects on the combustion characteristics are examined with three turbulence models: namely as the Reynolds stress model, spectral turbulence analysis and Re-Normalization Group. In addition, the P-1 and discrete ordinate (DO) models are used to simulate the radiative heat transfer in this model. The governing equations associated with the required boundary conditions are solved using the numerical model. The accuracy of this model is validated with the published experimental data and the comparison elucidates that there is a reasonable agreement between the obtained values from this model and the corresponding experimental quantities. Among different models proposed in this research, the Reynolds stress model with the Probability Density Function (PDF) approach is more accurate (nearly up to 50%) than other turbulent models for a swirling flow field. Regarding the effect of radiative heat transfer model, it is observed that the discrete ordinate model is more precise than the P-1 model in anticipating the experimental behavior. This model is able to simulate the subcritical nature of the isothermal flow as well as the size and shape of the internal recirculation induced by the swirl due to combustion.     

Erosion—corrosion characteristics of a 2.25 Cr-1 Mo steel exposed at low particle velocities

The erosion-corrosion characteristics of a 2.25 Cr-1 Mo steel at low particle velocities and elevated temperatures were determined using a nozzle type laboratory erosion tester. The tests were performed with 180–360 μm angular alumina particles at 60° angle of impingement at low particle velocities of 2.6–8.2 m/s and in the temperature interval 20–600°C. The steel was tested both in the as-received condition as well as in two preoxidized conditions. The erosion-corrosion rate of the steel, both in the as-received and in the preoxidized conditions, was found to increase with increasing particle velocity. In contrast, the wastage rates were relatively independent of temperature in the temperature range investigated, the only exception being specimens exposed to the lowest particle velocity (2.6 m/s) at the very highest temperature, i.e. 600°C, which displayed a drastic increase in wastage. Specimens preoxidized at 700°C exhibited a somewhat higher erosion rate compared with non-preoxidized specimens and specimens preoxidized at 500°C. Microscopy revealed four different major wastage mechanisms, i.e. (i) plastic deformation, cracking and micro chipping of surface material of a size corresponding to the area impinged by eroding particles, (ii) chipping of somewhat larger oxide fragments (up to 10–15 μm in diameter), (iii) chipping or spalling of relatively large oxide fragments (up to 30–50 μm in diameter), and (iv) spalling along the steel-oxide interface or within an oxide layer due to cohesive failure, of larger (up to 500 μm in diameter) oxide layer fragments. In the present study extensive spalling was only observed for non-preoxidized specimens exposed to the lowest particle velocity (2.6 m/s) and the two highest specimen temperatures (550°C and 600°C).     

Effects of a titanate coupling agent on the mechanical and thermo‐physical properties of talc‐reinforced polyethylene compounds

An experimental study was carried out to investigate the effects of a titanate coupling agent on the mechanical properties, moisture absorption, and thermal conductivity of talc‐filled high‐density polyethylene (HDPE). Talc (0–35 wt %) was used as reinforcement particulate filler in an HDPE matrix and samples were prepared in a micro‐compounder and an injection molding machine. Isopropyl tri(dioctyl)phosphate titanate (0.5 wt %) was used as coupling agent. Composites with and without coupling agent were evaluated for changes in mechanical and thermo‐physical properties, morphology, and void content. Addition of the titanate coupling agent most often resulted in an increase in stiffness and tensile strength. Furthermore, both the void content and the elongation at break of composites were reduced. Results also showed that the coupling agent had no effects on the thermal conductivity, thermal diffusivity, and specific heat capacity of the composites. In addition, it was observed that the coupling agent was more effective at low concentrations of filler. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40449.     

Long Distance Enhancement of Nonlinear Optical Properties Using Low Concentration of Plasmonic Nanostructures in Dye Doped Monolithic Sol–Gel Materials

Monolithic sol–gel silica composites incorporating platinum‐based chromophores and various types of gold nanoparticles (AuNPs) are prepared and polished to high optical quality. Their photophysical properties are investigated. The glass materials show well‐defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts of the AuNP plasmon absorption peaks due to the increase in nanoparticle doping concentration are observed in the glasses, proving that no or very small SPR coupling effects occur between the AuNPs. At 600 nm excitation, but not at 532 nm, the AuNPs improve the nonlinear absorption performance of glasses codoped with 50 × 10^?3 m of a Pt‐acetylide chromophore. The glasses doped with lower concentrations of AuNPs (2–5 μm average distance) and 50 × 10^?3 m in chromophore, show a marked improvement in nonlinear absorption, with no or only small improvement for the more highly AuNP doped glasses. This study shows the importance of excitation wavelength and nanoparticle concentration for composite systems employing AuNPs to improve two‐photon absorption of chromophores.     

爱立信IMS weShare分享每一天(系列之二)如何提供出色的用户体验?

爱立信IMS weShare业务有20%的开发与用户视觉体验相关(用户界面、图标、标签以及进度条),其它的80%则主要致力于设备间的系统.与此相对比,用户的体验则完全(100%)有赖于其可接触的事物.     

CAD standardisation in the construction industry — A process view

There has been a demand for uniform CAD standards in the construction industry ever since the large-scale introduction of computer aided design systems in the late 1980s. While some standards have been widely adopted without much formal effort, other standards have failed to gain support even though considerable resources have been allocated for the purpose. Establishing a standard concerning building information modeling has been one particularly active area of industry development and scientific interest within recent years. In this paper, four different standards are discussed as cases: the IGES and DXF/DWG standards for representing the graphics in 2D drawings, the ISO 13567 standard for the structuring of building information on layers, and the IFC standard for building product models. Based on a literature study combined with two qualitative interview studies with domain experts, a process model is proposed to describe and interpret the contrasting histories of past CAD standardisation processes.     

CAVE for collaborative patient room design: analysis with end-user opinion contrasting method

Several studies indicate that virtual reality (VR) systems are useful for end-user participation in an environmental design process. However, these systems can be costly and thus support for the decision whether to invest in a VR of some type is useful. This study presents a novel method for analysing the usefulness of a VR system for the purpose of end-user participation. We collected qualitative end-user opinion data in the real environment and then contrasted this data with the capabilities of a VR system. Additionally, to better understand the capabilities of the VR used, we examined how the end-users perceive the used virtual environment, which in this case was CAVE, an immersive VR system where projectors are directed to the walls of a room-sized cube. In this way, we analysed whether the same functions and elements identified by end-users on the actual wards could also be evaluated in the CAVE. Eleven nurses and 11 patients participated in the study by evaluating a bathroom and/or four patient rooms modelled by the CAVE and the actual hospital wards. The CAVE was convenient for evaluating most issues identified by the study participants in the actual hospital wards, i.e. aesthetics; correct location of equipment, supplies and materials; distraction by or the good companion of other patients as well as window position and size and living/workspace. However, it was not possible to evaluate with full certainty the possibilities for bracing against grab bars or other objects in the VR, and this was found to be relevant to the independent functioning of patients with limited mobility. Also, due to the relatively low luminance levels of projectors, evaluations regarding lighting were considered unreliable. Moreover, end-users were not always certain about the sizes and sufficiency of space in the CAVE. Solutions to overcome these limitations were proposed.