Economic impacts of power electronics on electricity distribution systems

To achieve more efficient energy use, power electronics (PEs) may be employed. However, these introduce nonlinear loads (NLLs) into the system by generating undesired frequencies that are harmonic in relation to (multiples of) the fundamental frequency (60 Hz in Brazil). Consequently, devices using PEs are more efficient but also contribute significantly to degradation of power quality. Besides this, both the conventional rules on design and operation of power systems and the usual premises followed in energy efficiency programs (without mentioning the electricity consumed by the devices themselves) consider the sinusoidal voltage and current waveforms at the fixed fundamental frequency of the power grid. Thus, analysis of electricity consumption reductions in energy efficiency programs that include the use of PEs considers the reduction of kWh to the final consumer but not the additional losses caused by the increase in harmonic distortion. This article contributes to a better understanding of this problem by reporting the results of a case study of the ownership and use of television sets (TV sets) to estimate the economic impacts of residential PEs on a mainly residential electricity distribution system.     

Alternative yeasts for winemaking: Saccharomyces non-cerevisiae and its hybrids

Wine fermentation has not significantly changed since ancient times and the most traditional aspects are seen by the market as elements that uplift wine nuances and quality. In recent years, new trends have emerged from the sector in line with consumer preferences, and due to the effects of global climate change on grape ripening. In the first cases, the consumers are looking for wines with less ethanol and fruitier aromas and in the second cases the wineries want to reduce the wine alcohol levels and/or astringency. New yeast starters of alternative Saccharomyces species and their hybrids can help to solve some problems that wineries face. In this article we review several physiological and genetic aspects of S. uvarum and S. kudriavzevii and the hybrids, which are especially relevant during the winemaking process, such as their good fermentative capabilities at low temperatures, resulting in wines with lower alcohol and higher glycerol amounts.     

MEMS传感整合解决方案

MEMS传感器包括测量线性加速度和地球重力矢量的加速度计、测量角速率的陀螺仪、测量地球磁场强度以确定方位的地磁计和测量气压以确定高度的压力传感器.把这些传感器整合在一起将会大幅扩大这些传感器的应用范围.本文以互补滤波器、卡尔曼滤波器和扩展型卡尔曼滤波器(EKF)为例,论述在一个传感器整合解决方案内如何让这些传感器协调工...     

Topographic Energy Management in Water Distribution Systems

A significant amount of energy is required to operate pressurised water distribution systems, and therefore, improving their efficiency is crucial. Traditionally, more emphasis has been placed on operational losses (pumping inefficiencies, excess leakage or friction in pipes) than on structural (or topographic) losses, which arise because of the irregular (unchangeable) terrain on which the system is located and the network’s layout. Hence, modifying the network to adopt an ecologically friendly layout is the only way to reduce structural losses. With the aim of improving the management of water distribution systems and optimising their energy use, this work audits and classifies water networks’ structural losses (derived from topographic energy), which constitutes the main novelty of this paper. Energy can be recovered with PATs (pumps as turbines) or removed through PRVs (pressure reducing valves). The proposed hydraulic analysis clarifies how that energy is used and identifies the most suitable strategy for improving efficiency as locating the most suitable place to install PRVs or PATs. Two examples are discussed to illustrate the relevance of this analysis.

     

Biosurfactant Production by Pseudomonas aeruginosa and Yarrowia lipolytica and Its Use for Detergent Formulations

This work reports detergents production using biological surfactants, microbiologically synthesized, and compares its foaming power and emulsification capacity to those presented by a petroleum based surfactant. Both used microorganisms were capable to produce surfactants, been able to emulsify oil/water mixtures and cause decrease of surface tension of water. The biosurfactant produced from Yarrowia lipolytica has a critical micelle concentration lower than that obtained from Pseudomonas aeruginosa （10 and 30 mg·Lt, respectively）, but the later showed better results in foaming power and emulsification experiments, similar to the synthetic detergent.     

Recycled multilayer cartons as cellulose source in HDPE‐based composites: Compatibilization and structure‐properties relationships

In this article, an alternative mechanical recycling of multilayer carton scraps (MC), consisting in the use of MC without the physical separation of its different fractions (cellulose fibers and low‐density polyethylene, 80/20 wt/wt), is proposed. In particular, MC was considered as a source of cellulose fibers in the obtainment of high‐density polyethylene (HDPE)‐based composites. Composites containing up to 60 wt % of milled MC were prepared by reactive processing, i.e., by adding different amount (5 and 10 wt %) of a linear low‐density polyethylene grafted with maleic anhydride (coupling agent, maleated linear low‐density polyethylene) during HDPE/MC mixing. Then, structure/properties relationships were deeply investigated as a function of MC and coupling agent content. The coupling agent was able to induce a complete polymeric covering of cellulose fraction as well as a strong HDPE/cellulose interfacial adhesion. As a consequence, a significant improvement of mechanical properties at low and high deformation rates as well as a very interesting response of composites to water vapor permeability was obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009