Showing papers by "Instituto Tecnológico de Morelia published in 2015"

Renewable energy resources short-term scheduling and dynamic network reconfiguration for sustainable energy consumption

Abstract: This paper proposes a two-phase approach for optimal short-term operational scheduling with intermittent renewable energy resources (RES) in an active distribution system. The first phase determines the amounts of purchased power from the market and the unit status of distributed generation (DG) and feeds the data into the second phase, a real-time scheduling coordination with hourly network reconfiguration. The two-phase proposed approach is applied to a case study of a sixteen-bus test system that uses synthetic data from renewable power generators and forecasts local user demands with a sampling time of five minutes.

Modeling the hot flow behavior of a Fe–22Mn–0.41C–1.6Al–1.4Si TWIP steel microalloyed with Ti, V and Nb

Abstract: The present research work analyses the influence of Ti, V and Nb microalloying elements on the hot flow behavior of a high-Mn Twinning Induced Plasticity (TWIP) steel. For this purpose, flow curves were obtained by uniaxial hot compression tests performed at four strain rates (10−1, 10−2, 10−3 and 10−4 s−1) and three temperatures (900, 1000 and 1100 °C). The models of Estrin, Mecking and Bergstrom; Avrami and Tegart, and Sellars were applied to determine the hot working constants used to derive the constitutive equations describing the flow curves. The analysis of modeling parameters of the hot flow curves shows that Ti, V and Nb additions to TWIP steel generated slight increase in the peak stress (σp), retardation of the dynamic recrystallization (DRX) onset, particularly at low temperature, and decrease in the activation energy required to recrystallization (Qt). Likewise, the softening effect promoted by DRV and DRX was more evident at high temperatures and low strain rates. On the other hand, the resulting deformed microstructures, analyzed by the SEM-EBSD technique, showed that the most important refining effect on recrystallized austenitic grain was in the presence of V and Ti. The good agreement between the experimental and predicted hot flow curves demonstrated that the developed constitutive equations predict with reasonable accuracy the hot flow behavior of the studied TWIP steels.

New Analytical Formulas for Electromagnetic Field and Eddy Current Losses in Bushing Regions of Transformers

Abstract: This paper presents a new and rigorous analytical calculation of electromagnetic field and eddy current losses in the zones of transformer tanks where bushings are mounted. This is done by solving Maxwell’s equations in the regions surrounding bushings, with the corresponding boundary conditions and considering linear permeability. Then, by solving the modified Bessel’s equation, the analytical formulas to calculate the magnetic field and eddy current losses in these regions are obtained and several cases are studied. The results are compared with 3-D finite element simulations and show very close correspondence. The obtained formulas allow straightforward calculations that can help designers to select proper parameters to optimize the design of transformers. This paper can be taken as the basis for the analysis of the nonlinear permeability case.

Resveratrol increases glycolytic flux in Saccharomyces cerevisiae via a SNF1 -dependet mechanism

Abstract: Evidence suggests that AMP protein kinase (AMPK) is the main target of the phytochemical resveratrol (RSV) in mammalian cells. Data also indicates that RSV stimulates glucose metabolism; however, the molecular link between RSV and glucose uptake remains unknown. Herein, we provide evidence indicating that RSV stimulates glycolysis via sucrose non-fermenting 1 gene (SNF1, Saccharomyces cerevisiae orthologous of AMPK). S. cerevisiae cultures treated with 30 μM RSV showed an increase in extracellular acidification rate compared to untreated cells, indicating an elevated glycolytic flux. Also, RSV treatment increased transcription levels of two key glycolytic genes, hexokinase 2 (HXK2) and phosphofructokinase 1 (PFK1), as well as production of NADH. Moreover, RSV treatment inhibited mitochondrial respiration when glucose was used as a carbon source. Importantly, the effects of RSV on glycolysis were dependent of SNF1. Taken together, these findings suggest that SNF1 (AMPK in mammalian systems) is the molecular target of RSV in S. cerevisiae.

Calculation of Nonlinear Electromagnetic Fields in the Steel Wall Vicinity of Transformer Bushings

Abstract: Successful analytical formulas have been previously proposed to calculate the losses in tank regions of transformers assuming linear permeabilities in the analyzed boundary-valued problem. This has resulted in easy-to-implement and low-cost computational design procedures from a transformer factory economical point of view. However, designers and analysts of transformers are constantly seeking new ways of reducing transformer losses in actual power networks with thousands of transformers. As a result, this paper has focused on proposing new analytical formulas to determine the electromagnetic field in bushing regions of transformers, taking account of the true nature of the nonlinear permeability behavior of the tank wall. This way, the nonlinear Maxwell’s equations in the regions surrounding the bushings are solved using an integral equation formulation that properly includes boundary conditions. A practical iterative procedure is thus proposed to solve the resulting nonlinear equation. The iterative scheme shows excellent numerical convergence properties with a very low computational demand as compared with finite-element (FE) nonlinear models. A comparison between our analytical results and those of 3-D FE simulations reveals a close match for a wide range of conductor currents. Hence, our new formulas can be used to improve the design of transformers, increasing their efficiency.

MWCNTs oxidation by thermal treatment with air conditions

Abstract: A process of functionalization, generally using acids, has to occur in order to use carbon nanotubes for different applications. The aim of this research was the oxidation of MWCNTs at air presence with thermal treatment. MWCNTs were obtained using benzene and ferrocene. The MWCNTs were heated into an electric furnace. Temperature ranged between 270 – 600 °C. The samples were characterized by SEM, EDS, XRD, FTIR and Raman. The results shown lost in weight percentage that fluctuated from 0 to 78% according to different temperature conditions. FTIR analysis demonstrated presence of carbonyl groups and decrease of CHx.

Takagi-Sugeno fuzzy model for DC-DC converters

Abstract: In this paper the analysis, design and simulation of a Takagi-Sugeno model for DC-DC converters, the buck-boost as a particular case study, are presented in order to analyze their performance compared to classical models of this converter. The model used for the Takagi-Sugeno fuzzy representation is the reduced nonlinear model. the Takagi-Sugeno fuzzy model is defined by eight rules and three parameters: input voltage (Vcc), capacitor voltage (vC) and inductor current (iL) in order to define the sector. The obtained results for the Takagi-Sugeno model simulation are compared to the obtained from the linear, nonlinear and reduced models.

Modeling Study of Molten Steel Turbulence Control by SEN Design Improvement in a Conventional Slab Caster

Abstract: A research study to improve the fluidynamics of a typical slab caster mould by redesigning the submerged entry nozzle (SEN) ports through a complete mathematical analysis was carried out, selected geometries are deeply tested and analyzed by physical modeling. For that a 1:1 scale analogue water model was constructed; PIV techniques, red dye tracer injections, and ultrasonic sensors are employed to study the molten steel flow patterns behavior. A comparison between the original and the improved SEN designs indicate that both geometries show weak double roll flow pattern at shallow position, but the two-roll flow pattern is well developed at a deeper position. The original design induces vortexes formation at either, shallow or deep immersion. In the other hand, the proposed improved design, where the backflow is eradicated, maintains good free surface stability without any vortex formation. The physical results indicate that the backflow phenomenon induces jet fluctuations, which are reflected in a more turbulent free surface, and its elimination provides more stable flow patterns in the mould.

Single DC-Sourced 9-level DC/AC Topology as Transformerless Power Interface for Renewable Sources

Abstract: This paper introduces an advanced transformerless multilevel hybrid-conversion topology intended for the interconnection of renewable DC sources at small-scale. The most important contribution presented in this paper is the generation of two isolated DC sources from a single DC source without the use of any type of transformer. The DC sources feed a nine-level DC/AC hybrid cascade multilevel converter. This advanced topology is achieved by redesigning the conventional DC/DC Buck topology, attached to the multilevel converter, and embedding a suitable switching strategy along with a Field Programmable Gate Array (FPGA)-based control. The advantages of the proposed structure, when compared to other proposals in the literature, are higher efficiency, reduced number of power switches, and high power density derived of transformerless characteristic. As a way to highlight differences and advantages of this converter over other options recently available in the literature, this paper carries out a quantitative evaluation comparing the number of voltage levels and the number of elements involved in the structure of DC/AC multilevel converters. The mathematical model and control strategy of the converter are explained and analyzed by means of simulations. Finally experimental results, obtained from a laboratory-scale prototype, show the performance of the system and demonstrate its relative advantages.

Network anomaly detection by continuous hidden markov models: An evolutionary programming approach

Abstract: Information security is an important and growing need. The most common schemes used for detection systems include pattern-or signature-based and anomaly-based. Anomaly-based schemes use a set of metrics, which outline the normal system behavior and any significant deviation from the established profile will be treated as an anomaly. This paper contributes with an anomaly-based scheme that monitors the bandwidth consumption of a subnetwork, at the Universidad Michoacana, in Mexico. A normal behavior model is based on bandwidth consumption of the subnetwork. The presence of an anomaly indicates that something is misusing the network viruses, worms, denial of service, or any other kind of attack. This work also presents a scheme for an automatic architecture design and parameters optimization of Hidden Markov Models HMMs, based on Evolutionary Programming EP. The variables to be used by the HMMs are: the bandwidth consumption of network IN and OUT, and the associated time where the network activity occurs. The system was tested with univariate and bivariate observation sequences to analyze and detect anomaly behavior. The HMMs, designed and trained by EP, were compared against semi-random HMMs trained by the Baum-Welch algorithm. On a second experiment, the HMMs, designed and trained by EP, were compared against HMMs created by an expert user. The HMMs outperformed the other methods in all cases. Finally, we made the HMMs time-aware, by including time as another variable. This inclusion made the HMMs capable of detecting activity patterns that are normal during a period of time but anomalous at other times. For instance, a heavy load on the network may be completely normal during working times, but anomalous at nights or weekends.

MWCNTs synthesis from butanol, diethyl ether, ethyl acetate and hexane by chemical vapor deposition with a stainless steel core as catalyst

Abstract: A stainless steel core catalyst with several green precursors, butanol, diethyl ether, ethyl acetate and hexane, were used to obtain multi-walled carbon nanotubes via chemical vapor deposition. Argon was used as carrier gas at 50-90 ml/min rates. Samples were synthetized at 680-850 oC, according to the precursor used. The characterization techniques were scanning electronic microscopy, X-ray diffraction, energy dispersive, Fourier transformed infrared and Raman spectroscopy. Themicrographs showed tangled carbon nanotubes formation with different diameters from 50-300 nm. Elemental analysis indicated carbon atomic percentages ranging from 93-99 %, 1.0-4.5 % iron and less than 1% of manganese, chrome and silicon. X-Ray diffraction demonstrated the characteristic carbon nanotubes peak (002)at 26°. G and D carbon nanotubes distinctive bands were confirmed by Raman spectra for all samples.

Validación experimental de un Observador de Alta Ganancia Reconfigurable para una columna de destilación

Abstract: In this paper the implementation and experimental validation of a high-gain reconfigurable observer for estimating the molar composition and temperature in a distillation column with a binary mixture is presented. The observer is composed by a simplified distillation column model and the error calculation and correction of this mathematical model. The main idea of the observer is the continuous reconfiguration of the observer gain in order to reduce the estimation error at every moment, thus achieving a faster convergence of the observer to the actual response of the system. The aim of this work is to verify the functionality of this observer by its online experimental validation in a distillation pilot plant process.

Reliability and availability of VSC-HVDC links: A state of the art

Abstract: This paper presents a documentary study about works related to the VSC-HVDC links reliability and availability assessment. The VSC-HVDC technology have proved to be a technical solution and cost effective choice to electric power transmission and occasionally it represents the only alternative to electric power transmission over the HVAC links to connect offshore wind-farms, for transmission over long distances and large bodies of water, for interconnection of two HVAC systems with different frequencies and for super-grids building. Since the VSC-HVDC technology provide multiple benefits in the electric power transmission and its technology is relatively young, is necessary known its behavior and models of reliability and availability which can lead to a wider use of this kind of links because the reliability and availability studies are very relevant to the implementation of new transmission system projects.

Harmonic interaction of the unified power flow controller with the electrical network

Abstract: SUMMARY The harmonic response and interaction of the unified power flow controller and the electrical network are presented in this paper. A UPFC model for harmonic studies is presented; this model incorporates all the basic operating characteristics that existing fundamental frequency UPFC models offer, such as active and reactive power regions. However, the harmonic model offers richer information such as harmonic distortion regions. The UPFC model is given in the form of equivalent impedance, which is connected to the AC system to perform harmonic propagation and resonance prediction analysis. By resorting to modularity, the UPFC model is obtained as the connection of two voltage source converters with the AC system and between themselves. The model is used to study the harmonic response of the UPFC and its interaction with the transmission lines. Copyright © 2014 John Wiley & Sons, Ltd.

Investigation of Wetting Front Propagation Dynamics Using Soil Impedance Measurements: Implications for Modelling and Irrigation Scheduling.

Abstract: The authors propose a measurement method that divides the depth of the soil sample in discrete regions to investigate soil water propagation dynamics using soil impedance measurements. Experiments were conducted on a cylindrical phantom using a clay loam soil sample (60 % clay, 21 % loam and 19 % sand). The resulting impedance changes represent the wetting front (WF) propagation process at the different measurement depths. The measured impedance data is used to A) show graphically the wetting front propagation process, obtain B) a 1st order model, C) an ARX1821 model of the impedance change as a function of the irrigation volume applied and D) estimating changes in water content using a neural network. The results indicate that the proposed measurement technique can be used to detect and predict the movement of liquid trough the soil sample. The neural network permits inferring the water content from impedance and soil-water mixture temperature values. Changes in soil impedance in each segment, due to the water propagating downwards through the soil sample, can be used to study the dynamics of the wetting front, irrigation scheduling and model improvement from physical data.

Producción de trehalosa a partir de levaduras no-convencionales

Abstract: La trehalosa es un disacarido formado por dos moleculas de D-glucosa, cuya estructura y propiedades fisicoquimicas unicas le confieren gran estabilidad. Este carbohidrato se acumula en el citosol de las levaduras bajo condiciones de estres abiotico debido a su efecto protector contra la desecacion, altas temperaturas, congelacion, alta salinidad y oxidacion. Debido a estas propiedades, la trehalosa tiene importantes aplicaciones en la industria alimentaria, cosmetica, farmaceutica y en la investigacion. Se realizo un analisis comparativo de la produccion de trehalosa en las levaduras no-convencionales Saccharomyces kluyveri, Candida shehatae y Candida guilliermondii, evaluando el efecto de dos temperaturas de crecimiento (28 y 34 °C y dos metodos de ruptura celular (mecanica con perlas de vidrio o termica mediante ebullicion). La tasa de crecimiento (celulas/mL) de las celulas cultivadas a 34 °C disminuyo en comparacion con el crecimiento a 28 °C. S. kluyveri produjo la mayor cantidad de biomasa en comparacion con las levaduras del genero Candida, C. shehatae fue la unica levadura en la cual no se detecto produccion de trehalosa bajo ninguna condicion de temperatura. Se determino que C. guilliermondii produce la mayor cantidad de trehalosa en relacion a las otras dos especies de levaduras en base a la prueba de Tukey-Kramer

New method of calculation of temperature distributions on transformer tanks

Abstract: A formula that calculates the distribution temperature in the transformer tank zones close to bushings is deduced. The new formula can use analytically or numerically obtained loss distributions. The comparison of the analytically calculated temperature distribution, using proven loss distributions, with finite element simulations, that use a thermal-electromagnetic coupled problem, shows that there is a very good match between numerical and analytical results. Apart, the new formula requires much lower computational resources as compared to finite element simulations that require commercial or highly specialized software. Our formula can provide to designers a powerful tool to improve efficiency and to increase useful life of transformers.

Control of Slag-Dragging Effects at the Metal–Slag Interface through Electromagnetic Brake in a Slab Mold

Abstract: Abstract Turbulent flow when steel is delivered through a nozzle in a slab mold induces dragging forces at the metal–slag interface that entrain slag droplets into the metal bulk. These dragging effects are discontinuous and correspond to the velocity fluctuations of turbulence at that interface which themselves, are dependent on nozzle immersion, nozzle design, mold width and casting speed. Slag viscosity and density, metal viscosity and slag layer thickness are employed to estimate that critical velocity which is embodied in a critical capillary number for some established mold operating conditions. This approach permits the link between all operating variables including flux chemistry and nozzle design with the interface instability. A relationship between the capillary number and the magnetic field strength used to brake the liquid steel is established which is used to assure the interface stability for any operating condition and flux chemistry.

New generation LOLAS: Redesign of an Optical Turbulence Profiler with High Altitude-Resolution

Abstract: We present the instrument and first results of a Low Layer SCIDAR (Scintillation Detection and Ranging), called new generation LOLAS (LOLAS 2), which consists of the optical coupling of a Ritchey-Chretien telescope and an EMCCD camera, and allows the measurements of optical turbulence profiles in the atmosphere from ground level with high altitude-resolution. The system is designed for widely separated double star targets, which enables a high altitude resolution of 5 ≤ Δh ≤ 35 meters above the first kilometer , measured from ground level. The first results were obtained in June and November 2013, and May 2014 at the Observatorio Astronomico Nacional de San Pedro Martir (OAN-SPM), Mexico.

Sequential algorithm-based model for the study of AC/DC power flow in VSC-MTDC systems

Abstract: Nowadays there is a widespread interest in the implementation of the super-grid concept using multi-terminal HVDC systems, MTDC. One useful tool to pursue this purpose is the availability of AC/DC power flow models. Nevertheless, the power flow models available in the literature do not provide a suitable approach to perform studies with AC transmission systems which integrate VSC-HVDC links and MTDC grids. In this work, a power flow model takes into account the stations VSC-HVDC of a MTDC system is presented. The model uses a programmable sequential algorithm which includes the study of the flows between the AC system and the MTDC. Therefore it allows to interconnecting multiples AC nodes by means of a MTDC. The algorithm is implemented using MATPOWER libraries.

Best practices for mobiles applications development. Developments carried out by small and medium enterprises in Mexico

Abstract: Software development for mobile platforms demands adapting and sometimes replacing current or traditional technologies and methodologies. The use of Agile Methods seems to be one of the handiest choices. Thus Prosoft has detected an area of opportunity and is now encouraging software development through various mechanisms, such as the creation of regional clusters focused on information technologies. This article presents an analysis towards identification of best practices in software development oriented to mobile platforms (APPs), which allow Mexican software factories to compete at national and international markets. This research is bound to Mexico's Midwest region defined by CANIETI and is directed to the generation of APPs. Several surveys were conducted, generating revealing results which are presented in depth.

Modeling transformer differential protection with harmonic restraint

Abstract: In this paper, a differential relay model (87T) is developed in the Alternative Transient Program for power transformer protection. The relay model uses an anti-aliasing filter and the Discrete Fourier Transform to calculate the relay operation and restriction currents. The relay model includes second, fourth and fifth harmonic restriction for blocking the relay operation during transformer energization and overexcitation. The relay model was successfully tested for different operating and fault conditions in a power transformer connected to the system. The results obtained validate the relay model and confirm its accuracy.