School location methodology in urban areas of developing countries

This study is concerned with the location of primary public schools. The public system should have the capacity to satisfy all the demand, although students may choose between public and private schools if they can afford the corresponding costs. A number of factors, such as questionable education quality, limited capacity, poor location and social preferences, secure a participation of about 30% to the private school system. The purpose of this study is both the evaluation of the existing public school network and a relocation proposal. The result of the former was the identification of areas with shortage and excess in school offer. The latter suggests school relocation using capacitated and uncapacitated models. ArcView, a software of the geographic information system (GIS) family, was employed, allowing the efficient handling of large problems and improving the presentation and evaluation of the findings. This methodology was applied to the primary public school network in the area of Vitoria, a state capital located in the southeast region of Brazil with about 300,000 inhabitants. Finally, the practical use of this study and its importance for planning purposes are discussed.     

X‐ray micrographic imaging system based on COTS CMOS sensors

This paper presents the use of commercial off the shelf CMOS image sensors for the acquisition of X‐ray images with high spatial resolution. The X‐ray images, with application in biology, electronic components inspection, and paleontology research, are obtained with 8‐keV photons from a Cu tube. The quantum efficiency of the detector is estimated using attenuation lengths of photons in the sensor and compared to traditional scintillator conversion layers. The spatial resolution observed with the sensor is limited by the charge redistribution produced after photon interaction with Si.     

Veni,vidi, vici: the success of wtf meiotic drivers in fission yeast

Meiotic drivers are selfish DNA loci that can bias their own transmission into gametes. Owing to their transmission advantages, meiotic drivers can spread in populations even if the drivers or linked variants decrease organismal fitness. Meiotic drive was first formally described in the 1950s and is thought to be a powerful force shaping eukaryotic genomes. Classic genetic analyses have detected the action of meiotic drivers in plants, filamentous fungi, insects and vertebrates. Several of these drive systems have limited experimental tractability and relatively little is known about the molecular mechanisms of meiotic drive. Recently, however, meiotic drivers were discovered in a yeast species. The Schizosaccharomyces pombe wtf gene family contains several active meiotic drive genes. This review summarizes what is known about the wtf family and highlights its potential as a highly tractable experimental model for molecular and evolutionary characterization of meiotic drive.     

Liquid Pool Copolymerization of Propylene/1‐Butene with a MgCl2‐Supported Ziegler‐Natta Catalyst

Summary: Liquid pool propylene/1‐butene copolymerizations were carried out in a batch reactor with a high activity Ziegler‐Natta catalyst system. Experimental runs were performed to evaluate the effect of the 1‐butene content on the crystallinity and melt temperature of the polymer resins. According to the results, 1‐butene can be significantly incorporated into the polymer chain at high polymerization rates over the whole range of copolymer compositions, leading to a decrease in the melting temperature (T_m) of the polymer, when compared to the poly(propylene) homopolymer, allowing for reduction of the sealing initiation temperature. It was observed by GPC and MFI measurements that the average molecular weights and the polydispersity index of the copolymer significantly decreased when compared to the ones obtained from poly(propylene). Despite high polymerization rates, polymer particles with good morphological features were produced in all cases. It was also observed that the absence of an external electron donor led to low crystallinity values for both the poly(propylene) homopolymer and for copolymers with different fractions of 1‐butene, when compared to literature values frequently reported for polymer resins based on 1‐butene and propylene. The obtained results indicate that a family of bulk propylene/1‐butene copolymer grades can be successfully developed for packaging and film applications.

Surface morphology and molecular weight distribution (deconvoluted into Schulz‐Flory distributions) of the propylene/1‐butene copolymer.     

Variable structure strategy to avoid amplitude and rate saturation in pitch control of a wind turbine

This work proposes the application of a recent compensation technique for input constraints avoidance to the pitch control of a wind turbine. The pitch angle actuators commonly present a hard limit on their rate of change together with the natural amplitude saturation, and a dynamics during their unconstrained operation that can be modeled as a first-order linear system. This dynamic behavior of the pitch actuator requires a particular design of the compensation method, which is based on variable structure systems to avoid both amplitude and rate input saturation by means of an auxiliary loop. The developed methodology reduces the pitch actuator activity necessary to regulate the generated power around its nominal value when facing sudden wind gusts. Another interesting feature of the proposal is that it allows the operator to fix conservative bounds for the actuator speed operation in order to increment the structural robustness of the wind turbine and to extend in this way the service life of the energy system. The effectiveness of the proposed strategy is evaluated by simulation results in an autonomous wind energy conversion system for water pumping with a brushless double feed induction generator (BDFIG).     

From simulation studies to experimental tests in a reactive dividing wall distillation column

The design and control of thermally coupled distillation sequences have been studied since many years, but the real implementation occurred until middle of the 1980s using a single shell divided by a wall named dividing wall distillation column. In this work, experimental results for the production of ethyl acetate in a reactive dividing wall distillation column are presented for first time. The experimental results are in agreement with those obtained using steady state simulations with AspenONE Aspen plus. These experimental results are important since it is possible to validate most of the previous results generated using simulations.