Acoustic pollution and its incidence in population health around bus station perimeter in Jipijapa city – Ecuador

<p style="text-align: justify;">This research entitled: " Acoustic pollution and its incidence in population health around bus station perimeter in Jipijapa city - Ecuador. " was carried out during 2017. The methodology used in this work was: observation prior determination of monitoring place, the application of survey, tabulation and interpretation of results. The monitoring was done during the two-month period. The monitoring was carried out on working days (Monday and Tuesday) and non-working (Sunday) at three key points of the perimeter of the bus station. Point 1 (front), point 2 (entry), point 3 (exit). After having monitored the noise pollution, the results were: The highest level of noise was presented in the month of June on Monday afternoon rush hours (12:30 pm to 1:00 pm) at point 1 (front side) ) of the perimeter of the terrestrial terminal with a maximum monthly average of 79.8 decibels dB (A). The month of July presented a higher level of noise pollution in point 1, with a maximum monthly average of 79.9 decibels dB (A), these levels exceed the permissible limits that is 55 decibels dB (A) in a mixed commercial zone according to TULSMA. The main source that generates noise is the horn of rural and provincial buses, cars, motorcycles with defective exhaust pipes, motor vehicles in poor condition, among others. The possible damages caused by the exposure of noise pollution in inhabitants of this area with physiological and psychological effects are: headache, stress, irritability and aggressiveness, hearing loss, nervous system alterations. In addition, the respondents said they do not agree that drivers make unnecessary noises with the horn of their vehicles and agree that noise control standards should be applied; the noise that bothers most is generated by the buses. It also presents a proposal that contributes to finding solutions in noise pollution and its effects on the health of the inhabitants.</p>

Circularly Polarized Microstrip Yagi Array Antenna with Wide Beamwidth and High Front-to-Back Ratio

A circularly polarized (CP) Microstrip Yagi array antenna (MSYA) is designed in order to achieve high front-to-back ratioR(F/B)and high gain over wide range in the forward radiation space. A Wilkinson power divider owning two output ways with the same magnitude and different phase is used to feed the antenna. Parametric studies are carried out to investigate the effects of some key geometrical sizes on the antenna’s performance. A prototype of the antenna is fabricated, and good agreement between the measured results and the numerical simulations is observed. The overlap bandwidth of VSWR ≤ 1.5 and AR ≤ 3 dB is about 11%. The steering angle (α) between the peak gain direction and the broadside can achieve 35°,R(F/B)reaches 19 dB, and the gain at the front point (G0) is only 4.3 dB lower than the maximum gain (Gm). The antenna has a wide beamwidth CP radiation pattern over wide spatial range including 0° ≤θ≤ 90° in vertical plane and −35° ≤φ≤ 55° in horizontal plane.

Virtual Prototype Modeling and Simulation of 8m Hydraulic Support

The mechanism of four-bar linkage for the 8m hydraulic support is designed and optimized with the help of graphing method. The 3D model of the 8m hydraulic support is created using the software Solidedge. The virtual prototype is built in the circumstance of multi-body dynamics analysis software Adams. The dynamic simulation is made for the hydraulic support from the maximum working height 8 meters to the minimum working height 5 meters. The movement trail of the front point of the hydraulic support is obtained which can explain and demonstrate the performance of the four-bar linkage. Meanwhile, the displacement, velocity and acceleration curves of the gravity center for the major components including the top beam, shield beam, front link and rear link are discussed.

Doubly symmetric finite-core heton equilibria

A finite-core heton is a baroclinic $f$-plane modon of a special type: it is composed of two patches of uniform quasi-geostrophic potential vorticity (PV) residing in different layers of a two-layer rotating fluid. This paper focuses on numerical construction of steadily translating, doubly symmetric, finite-core hetons and testing their stability. Such a heton, which possesses symmetry about the translation axis and the transverse axis, is a stationary solution to the equations of PV conservation in each of the layers when considered in a comoving frame of reference. When constructing the heton solutions and examining their bifurcations, we identify a heton by a pair of independent non-dimensional parameters, the half-length (in the translation direction) of a PV patch and the distance of the front point of the upper patch from the translation axis. The advantage of this method over other tried approaches is that it allows one to obtain solutions of new, previously unknown types. The results of testing the heton stability are presented on the plane made by a mean radius of a PV patch and the (horizontal) separation between the centroids of the patches. Two kinds of stability are tested separately, the stability to arbitrary perturbations that do not preserve the symmetry of the initial state and the stability to so-called symmetric perturbations that do not violate the initial symmetry. The hetons comparable in size with the Rossby radius, and smaller, are always stable in both senses. However, when some critical size is exceeded, the heton stability becomes dependent on the separation, and the larger the heton, the higher the separation required for stability. The separation guaranteeing the stability to symmetric perturbations is smaller than that required for the stability to arbitrary perturbations. Interrelations between instabilities and bifurcations are briefly discussed.