36 research outputs found
Evaluation and modeling of the variation of electromagnetic field on the cross section of a transmission line using finite difference method
This paper present a purpose to characterize power lines in order
to identify level of operation since the power grid planning. In
order to model a power line was required the use of
computational tools to generate a mathematical model in
MATLAB, which was based on the finite difference method and
represent the electromagnetic field (EMF) contribution. The
results were contrasted with real and measured values taken from
a cross section of a power line that was previously modeled.
Statistical analysis showed an accurate estimation of the electric
and magnetic field emitted by the line identifying the same shape
of the plotted curve and values in an acceptable range
Voltage collapse point evaluation considering the load dependence in a power system stability problem
Voltage Stability has emerged in recent decades as one of the most common phenomena, occurrence in Electrical Power Systems. Prior researches focused on the development of algorithm indices to solve the stability problem and in the determination of factors with most influence in voltage collapse to solve the stability problem. This paper evaluates the influence that the load dependence has with the voltage on the phenomenon of the voltage stability and especially on the characteristics the collapse point or instability point. Load modeling used is detailed and comparisons of the results obtained are made with those described in the bibliography and those obtained with commercial software. The results of the load margin are also compared when a constant load or a voltage-dependent load is considered as well as the values obtained at the maximum load point and the point of voltage instability
Effects of splitter Blade Length on disc pump performance
The disc pump operates using boundary layer principle and viscous drag with a relatively low efficiency. There are methods to increase head and efficiency, one of them is the placing of blades sectors or splitter blades in discs. This method has been applied only in the low viscosity fluids pumping (v < 0.1 stokes). This study describe an experimental research in a hight viscocity fluid (v = 2 stokes) with exit angle (32 = 35° and different splitter blades Lengths (Ls) (75, 50, 25%). The purpose is to determinate the splitter blades length that achieves the most effective combination between the blade effect and boundary layer effect in order to increase the energy transmission efficiency from the impeller to the fluid. As result, it can be established that the use of spliter blades is an alternative to increase the performance of the disc pump. The highest efficiency and head were obtained for the gapsize between two discs (b) of 12 mm using a 50% spliter blades length of the main blade length
Analysis of harmonic distortion generated by PWM motor drives
This paper evaluates the harmonic distortion generated by PWM motor drives in an electrical industrial system of a wheat flour mill company. For this, a comparative study between two industrial circuits connected at the same point of common coupling with similar characteristics of load and transformers is presented. The difference is that one circuit has PWM motor drives and the other does not have them. In the study, a practical method based on the statistical characterization of the total harmonic distortion of voltage (THDV) and current (THDI), individual voltage distortion (IVD), individual current distortion (ICD) and K-Factor is applied. As result, it was observed that PWM motor drives generated harmonics voltage mainly of fifth and seventh order with values that exceed limits established by standards in both circuits. In the work is also demonstrated that in the analysis of harmonics is necessary to consider various parameters and not only one
Energy planning for fuel oil saving in an industrial laundry
In this paper was applied a method of energy planning, compatible with ISO 50001 standard, in an
industrial laundry. In the analysis, three input variables were considered: level of production, technical
condition of the system and operating regime. The past, present and future of fuel oil consumption in the
steam generation and use was examined, establishing the causes of deterioration of consumption indicator.
A study of load and capacity in the system identified potential savings through improved operating regime.
A new regime for the operation of boilers was proposed and implemented, saving 16% of fuel. With the
results of these measurements, the baseline was developed and goals are established.En el presente trabajo se diseña y aplica un procedimiento de planificación energética, compatible con la
norma ISO 50001, a una lavandería industrial. Se analizan tres variables de entrada: nivel de producción,
estado técnico del sistema y régimen de operación. Se examina el pasado, presente y futuro del consumo
del fuel oíl en el sistema de generación y uso del vapor, estableciendo las causas del deterioro del indicador
de consumo. A través de un estudio de carga y capacidad en el sistema se identificaron las potencialidades
de ahorro mejorando el esquema de operación. Se propuso un nuevo esquema para la operación de las
calderas el cual fue implementado lográndose un ahorro del 16% de combustible. Con los resultados de
las mediciones se elabora la línea base y se establecen nuevas metas
Stress in butt welded joints of open profiles under torsion
In this paper is addressed how in the literature of Mechanic of Materials and Machine Elements Design
only few authors address the subject of welded joints, among those can be mentioned Shigley Hall,
Reshetov, and Faires [1, 3, 4-5]; although they provide expressions to calculate stress in complex geometric
configurations of welded joints, they do not analyze calculation for butt welded joints subject to torsion,
neither take into account characteristics of thin-walled side faces for the calculations. Only in the General
Treaty of Schimpke Welding, Horn and Ruge [7] are mentioned these features without addressing the
expressions for the calculation of stresses in cases of complex cases. Similar case is seen in articles and
specialized literature wheredelves into research on the technological parameters in welding, materials and
other subjects without addressing the improvement of calculation expressions to determine the stresses
in such joints. In this paper new expressions are shown for the calculation of tangential stresses arising
on the welds on butt joints of open profiles under free torsion, taking into account thin-wall side faces.En el trabajo se destaca como en la literatura de Mecánica de Materiales y Diseño de Elementos de
Máquinas, solo algunos autores abordan el tema de las uniones soldadas, dentro de estos se pueden citar
a Shigley, Hall, Reshetov y Faires [1, 3, 4-5]; estos autores, aunque brindan expresiones para el cálculo
de las tensiones en uniones soldadas de configuración geométrica compleja, no analizan el cálculo de
las mismas para el caso de estar sometidas a torsión, tampoco toman en cuenta para los cálculos las
particularidades de los perfiles de paredes delgadas, esto solo es analizado en el Tratado general de
soldadura de los autores Schimpke, Horn y Ruge [7], donde se mencionan estas particularidades sin
abordar las expresiones para el cálculo de las tensiones en casos complejos. Un tanto similar ocurre en
los artículos y literatura especializada, donde se profundiza en la investigación sobre los parámetros
tecnológicos en la soldadura, materiales y otros temas sin abordar el perfeccionamiento de las expresiones
de cálculo para determinar las tensiones en este tipo de uniones. En el presente trabajo se brindan nuevas
expresiones para el cálculo de las tensiones tangenciales que surgen en los cordones de uniones a tope,
en perfiles abiertos sometidos a torsión libre, tomando en cuenta para ello su consideración como perfiles
de paredes delgadas
Calculation model and methodology for stiffness evaluation in hydraulics cylinders
In the paper an analysis scheme able to considerate of all the main geometric and load factors that affect the behavior of a hydraulic cylinder in its action as a flexural-compression member. Also, experimental validations of the model are shown too. A methodology to identify the conditions leading to the instability of the cylinder is established
Calculation model and methodology for stiffness evaluation in hydraulics cylinders
In the paper an analysis scheme able to considerate of all the main geometric and load factors that affect the behavior of a hydraulic cylinder in its action as a flexural-compression member. Also, experimental validations of the model are shown too. A methodology to identify the conditions leading to the instability of the cylinder is established
Evaluación de fallas en un transportador de cangilones. Caso de estudio
A failure in the bottom sheet of a bucket conveyor (KZBQ.AUMUND)
during service was investigated. Sheets are
coupled to the chain throught a screw connection; they
operate in variable load scenarios causing fatigue. A
chemical and microstructural analysis was made showing
that sheet was built in steel with 0.15 % of Carbone without
alloying elements that contribute to the refined grain and
resistance increase. Strength calculation, used to
determinate safety factor, consider load system and type
material. Results concluded that geometry and thickness
value do not provide an adequate fatigue resistance
coefficient.Es investigada la falla en las láminas del fondo de un
transportador de cangilones KZB-Q.AUMUND durante su
servicio. Las láminas están acopladas a una cadena a través
de uniones atornilladas y operan bajo un régimen de cargas
variables causándoles fatiga. Se realiza un análisis químico y
microestructural el cual evidencia que las láminas fueron
elaboradas de un acero con 0,15 % de carbono sin
elementos de aleación que contribuyan al afinamiento del
grano y al incremento de la resistencia. Se calculan las
tensiones para determinar el coeficiente de seguridad a la
fatiga considerando el sistema de cargas y el material de las
láminas. Los resultados concluyen que la geometría y los
valores de espesor no le proporcionan a las láminas un
adecuado coeficiente de resistencia a la fatiga
Mathematical modeling of vertical movement of the upper shaft in cane mills
This study introduces a mathematical model to describe the floating effects of the top roll in sugarcane mills. The model is developed from experimental data measured during the operation of a sugarcane mill. The measured data is fitted using the top shaft rotation period of the mill and dividing on intervals to individually fit each interval obtaining a function defined by parts. The resulting model shows a correlation coefficient of R2 ≥ 0.97. This allow including the floating effect in the study and design of other elements of sugarcane mills