Electrodynamic formulation of special relativity from the first postulate

This work presents the form that the special theory of relativity takes when only the first postulate and the properties of homogeneity and isotropy of space and time are considered valid. The transformations of Lorentz coordinates are obtained in terms of a universal constant parameter k, developing from these the relativistic kinematics, dynamics and electrodynamics and their respective invariances before these transformations

Multicriteria strategic approach for the selection of concrete suppliers in a construction company in Colombia

Within companies of the construction sector, the evaluation and selection of concrete suppliers, is considered a fundamental topic for the adequate construction of buildings, due to the impact it has, not only in the stability of the building but also in the productivity and the profitability. For an adequate selection, decision-makers must consider a series of criteria of different kind. However, as in different fields, due to the numerous criteria and alternatives that should be considered in the construction industry, the choice of an appropriate multicriteria decision-making approach has become a critical step in the selection of suppliers. Therefore, the objective of this research is to define the most adequate supplier of suitable concrete through the integration of powerful multicriteria decision-making methods. For this purpose, a fuzzy analytical hierarchy process (FAHP) is initially applied to define initial factor weights under uncertainty, followed, using the decision-making test and the evaluation laboratory (DEMATEL) to evaluate the interrelationships between elements of the hierarchy. Then, after combining FAHP and DEMATEL to calculate the final contributions of the factors including the interdependence, finally TOPSIS technique is used for the order of preference for the similarity with the ideal solution to evaluate and determine the best supplier

Elements of a gravitational lens system assuming an elliptical galaxy model

This work studies some elements of gravitational lensing by galaxies such as the lens equation, deflection angle, lensing potential and time delay, modeling the mass distribution of the lensing galaxy as an elliptical galaxy. The mass distribution function ρ of the deflecting galaxy indicates that it has a nucleus with radius a in its core, a free-form parameter b (b > a), and that the mass density of the nucleus is ρ0. The mass density distribution ρ allows us to find the surface mass density Σ (projected on the plane of the lens), followed by general elements of the gravitational lens expressed in terms of the geometric parameters a and b. The relation between these parameters is defined by the adimensional factor n = b/a > 1. The results of this work can be applied to any galactic lens system to conduct an analysis based on the temporal delay between two images and to determine the conditions that must be satisfied by the parameter n

Reactive power sharing in microgrid using virtual voltage

The traditional droop control strategy has been applied previously in microgrids (MGs) to share accurately the active power. However, in some cases the result obtained when sharing reactive power is not the best, because of the parameters related to the distances from distributed generators (DGs) to the loads and the power variations. Therefore, this paper proposes a reactive power control strategy for a low voltage MG, where the unequal impedance related to the distances between generators and loads requires adjustments to work with the conventional frequency and voltage droop methods. Thus, an additional coefficient is calculated from parameters of the network that relate the location of elements. The test is perfomed by simulations in the MATLAB-Simulink software, considering a three-node MG with three DGs and a load that can change power at different periods of time. The results show that it is possible to improve reactive power sharing between the DGs located in the MG according to the load changes simulated and to improve voltages with this method

Studies on strength characteristics of black cotton soil by using novel SiO2 combination as a stabilizing agent

The rapid growth in industrialization and population leads to generation of large quantity of wastes, some materials were containing high silica contents is damped as a waste. In this study such damped silica wastes from various industries is collected and subjected to studies as a stabilizing material for black cotton soils, such assorted materials are Fly ash, GGBS, Rice husk ash, Precipitated silica and Calcium chloride. By effective nanoparticle studies like SEM, EDAX, presence of silica, aluminum and magnesium proportion in each industrial waste is formulated. From the result of nanoparticle analysis novel silica combination prepared by composition of all those materials based on cementanious action mineral presence. In before studies one or two combinations only used as stabilizer but in this paper a new group bearing binder combination is designed and their behavior with chosen geo material and its respective engineering, strength and hydraulic properties is studied by Constantine combination proportion to 20% to weight of soil. Properties such as California bearing ratio (CBR), and North Dakota of the soils were determined with the addition of stabilizers. From the results engineering properties of the poor engineering graded soil were improved is clearly visualized. For the normal soil and effective result binder proportion, a comparison in finite element analysis using PLAXIS is carried out for footing study. Finally, the study showed that exact cementanious mineral combination from industrial waste could improve the geotechnical properties of highly inorganic soil

Familial association of genetic generalised epilepsy with limb-girdle muscular dystrophy through a mutation in CAPN3

Muscular dystrophies are a heterogeneous group of inherited dis-eases that cause progressive muscle weakness. The association of epi-lepsy with some of these diseases has been previously described andhas most commonly been found for Fukuyama-type muscular dystro-phy due to alterations in cerebral neuronal migration[1]. Among mus-cular dystrophies, limb-girdle muscular dystrophies (LGMDs)represent the fourth most common group, with a prevalence of 1.63per 100, 000 individuals[2]. The diseases in this group share a commonphenotype involving progressive weakness of the scapular and pelvicgirdles that starts after 2 years of age and can be accompanied by differ-ent degrees of elevation in blood creatine kinase (CK) levels and by var-ious anatomic pathologicalfindings. LGMDs are subdivided into LGMD1and LGMD2 depending on whether the inheritance is dominant or re-cessive, respectively. LGMD2A, which is caused by deficiency of thecalpain 3 protein owing to mutations in theCAPN3gene, is the mostcommon form of LGMD in Europe and America[2]. Its associationwith epilepsy has been described in only two isolated cases[1, 3], bothof them on the spectrum of genetic generalised epilepsies (GGEs). Thelatter are the most common group of epilepsies with genetic aetiology, accounting for 15–20% of all epilepsy cases[4]. Nonetheless, none of thegenes usually involved in monogenic epilepsies seem to play a majorrole in GGE, probably indicating a polygenic predisposition to GGE andtherefore a complex inheritance pattern[5]. Here, we describe a family..

Heat and mass transmission of an Oldroyd-B nanofluid flow through a stratified medium with swimming of motile gyrotactic microorganisms and nanoparticles

This paper focuses on the research of motile microorganism rates in the bioconvective Oldroyd-B nanoliquid flow over a vertical stretching sheet with mixed convection and inclined magnetic field. Additionally, interesting characteristics of thermophoresis, Brownian motion, viscous dissipation, Joule heating, and stratification are examined. Similarity transformations are employed to reduce the mathematical model to higher-order ODE. The convergent serious solution is applied to solve the nonlinear differential system. The analysis of temperature, velocity, motile microorganisms’ density, and nanoparticle concentration are represented through graphs. Local Nusselt number, density number of motile microorganisms, and Sherwood number are examined via contour plots

Algorithms for crime prediction in smart cities through data mining

The concentration of police resources in conflict zones contributes to the reduction of crime in the region and the optimization of those resources. This paper presents the use of regression techniques to predict the number of criminal acts in Colombian municipalities. To this end, a set of data was generated merging the data from the Guardia Civil with public data on the demographic structure and voting trends in the municipalities. The best regressor obtained (Random Forests) achieves a RRSE (Root Relative Squared Error) of 40.12% and opens the way to keep incorporating public data of another type with greater predictive power. In addition, M5Rules were used to interpret the results