The changes in structural properties of high density polyethylene films (HDPE), low (LDPE), biodegradable (PE-BIO), and oxodegradable (PE-OXO) exposed to UV-B radiation were studied. carbonyl<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mrow><mml:mi>I</mml:mi></mml:mrow><mml:mrow><mml:mtext>C</mml:mtext><mml:mtext>O</mml:mtext></mml:mrow></mml:msub><mml:mo stretchy="false">)</mml:mo></mml:math>and vinyl<mml:math...

This paper presents the results of an experimental study carried out to comprehend physical, mechanical, and microstructural behavior cement pastes subjected static magnetic fields while hydrating setting. The methodology consisted in exposing fresh at three different induction strengths: 19.07, 22.22, 25.37 Gauss. characterization makes evident that there are differences relation amount morphology CSH gel; is larger its becomes denser less porous with higher magnetostatic strengths; it also...

This article presents the modeling and fabrication of photonic devices such as a Mach-Zehnder waveguide interferometer (MZWI) 1 × 4 optical power splitter (OPS) with microfluidic channel. The structures were designed using CAD software BeamPROPTM to have an s-shaped bend geometry total length 8000 μm, then integrated 6000 μm channel form configurations based on conical spirals helices femtosecond laser radiation. entire writing process was performed in single step 20X microscope objective...

Abstract Different types of commercial polyethylene films, low‐density (LDPE), high‐density (HDPE), and biodegradable (BIO‐PE), were exposed to UV‐B radiation at different exposure time domestic composting during spring fall ambient conditions. The effects on LDPE, HDPE, BIO‐PE degradation characterized by FTIR spectroscopy. underwent photo oxidation reactions leading the formation carbonyl (CO) vinyl (CH 2 CH) groups hydrophilic surface modification. Also, conditions seasons suffered...

Tracking systems with stringent performance are required to take advantage of solar energy produced through the use high concentration photovolatics and concentrating power technologies. Closed-loop tracking measurements provided by a sun sensor, which picks up direct diffuse sunlight. High levels sunlight produce increased measurement noise at output in turn limits maximal achievable gains closed-loop controller consequently deteriorates. The goal this paper is present advantages equipping...

In this paper we report the application and evaluation of simulated annealing (SA) optimization method in parameter estimation for vapor-liquid equilibrium (VLE) modeling. We tested using classical least squares error-in-variable approaches. The reliability efficiency data-fitting procedure are also considered different values algorithm parameters SA method. Our results indicate that method, when properly implemented, is a robust nonlinear thermodynamic models. However, difficult problems it...

This work presents the results by irradiating fresh Portland cement pastes with CO2 laser, at powers of 1.6, 2.0, and 2.4 W, different water-to-cement (w/c) ratios 0.4, 0.45, 0.5. Raman spectra show evolution accelerated growth main hydration products through intensity changes signal. The shifts reveal that C-S-H, CH, AFt, CaCO3 bands are detected in a shorter time, which means setting times also reduced. band calcium carbonate, is due to incorporation limestone during grinding process,...

Phase equilibrium calculations in systems subject to chemical reactions play a major role the design of reactive separation schemes including reaction engineering. Basically, these involve global minimization Gibbs free energy constrained by material balances and restrictions. However, function is non-convex, highly non-linear with many decision variables, may have several local minimums trivial nonphysical solutions. In conditions, conventional numerical methods are not suitable for solving...

This article presents the results of treatment fresh cement pastes with CO2 laser radiation (10.6μm), in order to improve its mechanical properties addition obtaining lower setting times than those a natural (without .) It was observed that has positive influence on paste, not due heat produced during irradiation, but effect electric field propagation water molecules, whose are arranged around functional groups binder and by ration, causes micro vibration effect, resulting more compact less...

In this work, a nondestructive and noninvasive technique, based on laser technology the use of Kubelka-Munk model to calculate dynamic behavior cement paste from diffuse reflection properties both components hydration products, is proposed. Also, Powers-Brunauer used explain during first 9 h process. This method allows us obtain initial final setting times measurements.

In this work the changes occurring in cement pastes irradiated by 10.6µm CO2 laser at different stages of hydration after preparation are presented. Raman spectroscopy, X-ray diffraction and Scanning Electronic Microscopy (SEM) techniques had been used to observe molecular structural changes. Intensity paste peaks   irradiation was monitored samples 2, 3, 4, 5, 6, 7, 8, 9, 10 11 days their preparation. Applied power changed peaks intensity 187.5cm-1, 563cm-1, 695cm-1, 750cm-1, 897cm-1,...

Abstract We report the evaluation of superficial degradation orange and colorless linear low density polyethylene samples exposed to weather. Color change UV–VIS absorption were measured on weather conditions city Aguascalientes, Mexico, for more than a year. The color was calculated in CIELAB units. presented an exponential decay with time samples, whereas they remained constant samples. No products from polymer matrix revealed by spectroscopy, apart change, no other noticed. © 2009 Wiley...

<title>Abstract</title> This work presents a novel method for using ranking statistics in the assessment of meteorological drought threat, applied to drought-prone region Aguascalientes Mexico, which can serve identify local climate regions. Extreme poses risk human health, economy, and survival, aside from its ecological effects. One way study assess threat complex catastrophic events such as earthquakes, hurricanes, others is by statistics. Such has not been used analyze droughts. Here,...

This work carries out a simulation of the absorption spectra on IR an untinted textile fiber manufactured with polyacrylonitrile (PAN), obtained by calculating Molecular Orbitals (MOs) and their associated energies based semiempirical (AM1) Hartree-Fock (HF) model compared experimental results from PAN blue pigment means FTIR Avatar Nicolete spectrophotometer.

Thermooxidation of LDPE films by CO 2 laser radiation, 10.6 μ m, was characterized Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR). The formation carbonyl and hydroxyl functional groups onto dependent on the fluency laser. IR absorption vinyl C-O bond present in alcohols showed a decrease an increase, respectively, indicating that radiation causes simultaneous accumulation hydroperoxides films; furthermore, crystallinity irradiated tends to increase. So,...

Polarized Raman spectra have been obtained from polyacrylonitrile copolymers fibers with vinyl acetate Poly(AN-co-VA), and methyl acrylate Poly(AN-co-MA) finishing without finishing, in order to show the effect of optical rotation scattered light. The polarized were used calculate depolarization ratios for both fibers. These values reveal that there is antisymmetric scattering form anomalous some bands due a dipolar interaction between polar headgroup nitrile group fiber causing changes...