Bandwidth compression of noisy signals with square-wave subcarrier

This article discusses a method for downconverting the square-wave subcarrier of spacecraft signals, such as the one from Galileo, which results in a compression bandwidth that lowers the sample rate significantly. The study is focused on three issues. The first is the selection of an adequate down-mixing signal for the resulting signal to have a format similar to that of the original signal, except at a lower subcarrier frequency. The second is the control of the noise level so that the signal to noise ratio is not degraded due to the downconversion. The third is to determine the bandwidth of the downconverted signal considering the uncertainty of the residual carrier frequency

Symbol signal-to-noise ratio loss in square-wave subcarrier downconversion

This article presents the simulated results of the signal-to-noise ratio (SNR) loss in the process of a square-wave subcarrier down conversion. In a previous article, the SNR degradation was evaluated at the output of the down converter based on the signal and noise power change. Unlike in the previous article, the SNR loss is defined here as the difference between the actual and theoretical symbol SNR's for the same symbol-error rate at the output of the symbol matched filter. The results show that an average SNR loss of 0.3 dB can be achieved with tenth-order infinite impulse response (IIR) filters. This loss is a 0.2-dB increase over the SNR degradation in the previous analysis where neither the signal distortion nor the symbol detector was considered

SNR degradation in square-wave subcarrier downconversion

This article presents a study of signal-to-noise ratio (SNR) degradation in the process of square-wave subcarrier downconversion. The study shows three factors that contribute to the SNR degradation: the cutoff of the higher frequency components in the data, the approximation of a square wave with a finite number of harmonics, and nonideal filtering. Both analytical and simulation results are presented

ASPHALT PAVEMENT DESIGN ALTERNATIVES FOR ROADS WITH LOW AND MEDIUM TRAFFIC VOLUMES IN CLAYEY SOILS IN THE CITY OF SINCELEJO

The design of pavements is a work of civil engineers, who seeks provide structures that are resistant to traffic loads and the effects adverse effects of the environment, so that they can be built properly and manage to provide their users with a comfortable and safe experience, at the least possible cost. To achieve this objective, it is necessary to choose a design methodology according to the characteristics of the project and determine as precisely as possible, each of the variables involved in the design, taking into consideration that many of the design methodologies are empirical in nature, which in some way puts try the designer experience. It is for this reason that designs require multiple studies, which are usually costly in financial resources and time. All of the above, many institutions have taken on the task of developing design primers that allow obtain pavement structures based on the input of few parameters and obtain applicable solutions for most projects; however, they must be taken into account the limitations of these primers and their application environment, given the case, that many of them must be calibrated, to certain particular conditions of the project area, with the aim of objective of optimizing resources and guaranteeing lasting works. The objective of this work is to make an asphalt pavement design primer based on the methodology of AASTHO 1993 design, which allows finding a suitable design alternative for projects located in the city of Sincelejo, north of Colombia. For this purpose, it carried out studies of soils in clayey subgrades, which predominate in the town of study and that they classify as CL to obtain their bearing capacity values (CBR). Additionally, various levels of traffic were selected, which can occur and are defined the typical pavement structures. For method design parameters, the typical values expected in the study area were used, which resulted in, a design primer that is made up of twenty transit levels and four pavement structure alternatives, for each case, that satisfy these requests

Nonlocal electron heat flux revisited

A known nonlocal model of electron heat flux, applying for (scale length/thermal ion-electron mean-free path) of order Z)1/2(e*/T)312, ionization number Z, large, and e*~ 6.5 T (the energy of electrons carrying most of the flux), is reconsidered. The large e*/T ratio simplifies the complete formalism. A simple flux formula, exact for both smooth and steep profiles, is given. Thermoelectric effects and other models are discussed

Nonlocal electron heat relaxation in a plasma shock at arbitrary ionization number

A recently obtained nonlocal expression for the electron heat flux valid for arbitrary ionization numbers Z is used to study the structure of a plane shock wave in a fully ionized plasma. Nonlocal effects are only important in the foot of the electronic preheating region, where the electron temperature gradient is the steepest. The results are quantified as a function of a characteristic Knudsen number of that region. This work also generalizes to arbitrary values of Z previous results on plasma shock wave structure

Relationship of the verbal fluency index profile with the variables age, educational level, and sex in a group of schoolchildren

This is a quantitative, descriptive, cross-sectional, and correlational study, whose purpose was to relate the profile of the verbal fluency index-VFI with the variables of age, sex, and educational level of a schoolchildren group from an official educational institution in the department of Sucre, Colombia. The sample consisted of 390 students distributed in 176 of BPE and 214 of BSE to whom the verbal fluency test reviewed by Ardilla and Rosselli (2007) was administered. The Microsoft Excel 19.0 statistical program was used for data coding and the EZAnalyze version 2.5 add-in was used for processing. The results showed that the phonological verbal fluency, semantic, and general index tests were below the normative mean. The association between the VFI with the variables age and school grade was confirmed with the parametric test of Pearson's coefficient with a high level of significance p=0.000. However, gender had no influence on performance because there was no correlation. It is concluded that the VFI increases with age and school grade, factors that imply that as they increase, it will allow a progressive tendency to access the lexicon, the ability to name words according to phonemic indication, and from a given category

Experimental Local Loss Coefficients (Km) Of Some Common Fittings Used In Residential Hydraulic Networks

The loss coefficients values (Km) of hydraulic fittings produce energy losses that are related to the minor ones (hL) and are widely used in hydraulic network designs. In this work, through a loss bank, the most common fittings Km coefficients used in residential hydraulic installations in Colombia were found, such as 90° elbows, universal joints, reductions, and ball valves from ½ to 2 inches in diameter. Among the results found, it was evidenced that the smaller the diameter, the load losses, the velocity, and the loss coefficient increase. An analysis of variance (ANOVA) was performed to corroborate the results obtained and, in most cases, reliability greater than or equal to 90% was achieved

Self-consistent, nonlocal electron heat flux at arbitrary ion charge number

A single, nonlocal expression for the electron heat flux, which closely reproduces known results at high and low ion charge number 2, and “exact” results for the local limit at all 2, is derived by solving the kinetic equation in a narrow, tail-energy range. The solution involves asymptotic expansions of Bessel functions of large argument, and (Z-dependent)order above or below it, corresponding to the possible parabolic or hyperbolic character of the kinetic equation; velocity space diffusion in self-scattering is treated similarly to isotropic thermalization of tail energies in large Z analyses. The scale length H characterizing nonlocal effects varies with Z, suggesting an equal dependence of any ad hoc flux limiter. The model is valid for all H above the mean-free path for thermal electrons

The quality of higher education from the point of view of the contributions made by graduates in their work environment

Objective: The objective of this paper was to analyze higher education quality, considering the contributions made by graduates in their work environment.  The ontological context was determined by the Master's program in Education of the Caribbean University System (SUE Caribe) at the University of Sucre from Sincelejo, Colombia. Method: The study was developed within the framework of the qualitative approach, with a case study design, cross-sectional in two stages: documentary review and field research. A semi-structured interview was applied to an intentional sample of 13 graduates selected through cluster, proportional, and random sampling. Data analysis was executed using ATLAS Ti software version 7.5.4, It takes into account three levels of categories: core, relational, and descriptive. Results: the graduates interviewed are located in the educational sector, It shows good performance in the following competencies: research, educational management, and social projection, and are recognized by the community. Discussion and Conclusions: considering the graduate as the unit of analysis, the program exceeds the qualified registry requirements and meets the high-quality requisites.&nbsp