FPGA-based implementation of online selective harmonic elimination PWM for voltage source inverter

This paper presents a field programmable gate array (FPGA)-based real-time selective harmonic elimination pulse width modulation (SHE-PWM) scheme for voltage source inverter (VSI). The proposed algorithm can generate the switching angles in real time through the approximation of the angles trajectories by simple variable coefficients-based polynomial equations. The proposed algorithm is first presented, analysed, and then its accuracy is checked through angle error analysis. Afterwards, an FPGA-based implementation is used and an induction motor drive is experimentally tested to validate the simulation results. Experimental results showed a good agreement with simulation and proved the validity as well as precision of the proposed algorithm. All intended selected harmonics are eliminated and simultaneously the fundamental is controlled. The output voltage and current present an excellent frequency spectrum with low harmonic distortion and power loss values.     

Silk Fiber-Reinforced Hyaluronic Acid-Based Hydrogel for Cartilage Tissue Engineering

A continuing challenge in cartilage tissue engineering for cartilage regeneration is the creation of a suitable synthetic microenvironment for chondrocytes and tissue regeneration. The aim of this study was to develop a highly tunable hybrid scaffold based on a silk fibroin matrix (SM) and a hyaluronic acid (HA) hydrogel. Human articular chondrocytes were embedded in a porous 3-dimensional SM, before infiltration with tyramine modified HA hydrogel. Scaffolds were cultured in chondropermissive medium with and without TGF-β1. Cell viability and cell distribution were assessed using CellTiter-Blue assay and Live/Dead staining. Chondrogenic marker expression was detected using qPCR. Biosynthesis of matrix compounds was analyzed by dimethylmethylene blue assay and immuno-histology. Differences in biomaterial stiffness and stress relaxation were characterized using a one-step unconfined compression test. Cell morphology was investigated by scanning electron microscopy. Hybrid scaffold revealed superior chondro-inductive and biomechanical properties compared to sole SM. The presence of HA and TGF-β1 increased chondrogenic marker gene expression and matrix deposition. Hybrid scaffolds offer cytocompatible and highly tunable properties as cell-carrier systems, as well as favorable biomechanical properties.     

Influence of graphene oxide surface treatment by diazonium salts on thermoelectrical behavior of polypyrrole-based composites

Journal of Materials Science: Materials in Electronics - In this study, we investigate the influence of crude and surface-treated graphite by diazonium salt on the thermoelectric (TE) properties of...     

ITMA回顾：纺纱

着重从技术革新和技术关键方面介绍了本次展览中纺纱准备工序的发展情况。总体来讲，在改进工艺、提高质量和劳动生产率、方便操作及推进自动化方面显然在进行着不懈的努力，但没有非常的大的技术革新。尽管世界范围内纺织工业普遍比较萎缩、世界纺织工业中投资活动较少，但包含机器更新在内的更广泛的资金投入已经议事日程上了，这就是本次展览会上纺纱方面急切期待最新发展的原因。这些都概括在报告中。     

Effect of Cloisite® 30B on the Diffusion of Irganox 1076 in HDPE

The diffusion of a thermal stabilizer, Irganox 1076, is studied both in pure high‐density polyethylene (HDPE) and HDPE matrix filled with 1 wt% of Cloisite® 30B. The diffusion experiments are carried out by using the Roe method formed by a stack of several polymer films of 120 ± 01 μm in thickness. In this study, a simple method is used to measure the diffusion coefficient, with the aid of Fourier Transform InfraRed spectroscopy without any extraction or refining steps in the analysis. The diffusion coefficient (D_p) of both materials are obtained in the temperature range 80–100°C using the second Fick's law. By applying the Arrhenius equation to the calculated D_p coefficients, an estimation of activation energies of the diffusion process is also achieved. The results indicate that the diffusion coefficient of Irganox 1076 in HDPE has been decreased by adding 1% of Cloisite® 30B.     

Experimental study of the evaporation of a falling film in a closed cavity

This article concerns the experimental study of heat and mass transfer in a distillation cell. This latter is a parallelepiped, of large form factor, whose active walls are vertical. The cell is fed with salt water, and pure water is evaporated from a thin film that falls along a heated wall while the opposite wall is maintained at a lower temperature and is used as a condensation surface. The experimental results show that the heat transfer in the distillation cell is dominated by the latent heat transfer associated with evaporation. A parametric study of the behavior of the distillation cell has been performed. A convenient choice of the operating parameters is suggested to optimize the distillation yield.     

Comparison of tensile,thermal, and thermo‐mechanical properties of polyester filaments having different cross‐sectional shape

One of the most important morphological features of fibers is their cross‐sectional shape. Nowadays, the circular fiber cross‐section is the most common shape of melt‐spun man‐made fibers. Other shapes are beginning to emerge for a variety of reasons such as performance, comfort, pilling propensity, bulkiness, tactility, processing etc. The filaments' cross‐section can be easily varied by changing the spinneret hole shape. Synthetic fibers that are predominantly spun by the melt spinning method with spinnerets having the noncircular hole geometry are called profiled or noncircular fibers. Modifications of the fiber cross‐section allow designing surface properties in yarn and fabric. However, the effect of profiled fibers on yarn properties has not been well documented yet. In this article, the influence of different filament cross‐section geometry on fiber properties was studied. PET (polyethylene terephthalate) filament yarns having two different cross‐sectional shaped filaments, circular and cruciform, were manufactured by melt spinning. Differences in tensile properties of filament yarn and as well as of individual filament depending on the cross‐sectional type were studied and revealed. More over, thermal and thermomechanical properties of filament yarn of both the cross‐sections were studied and revealed by DSC and TMA method, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

RFID Authentication Protocols Based on Error-Correcting Codes: A Survey

Code-based cryptography is a very promising research area. It allows the construction of different cryptographic mechanisms (e.g. identification protocol, public-key cryptosystem, etc.). McEliece cryptosystem is the first code-based public-key cryptosystem; several variants of this cryptosystem were proposed to design various security protocols in different systems. In this paper, we present a survey on various and recent authentication protocols in radio frequency identification systems which use diverse variants of the McEliece cryptosystem. Moreover, we discuss the security and the performance of each presented protocol.