bluuebunny/crossref_metadata_2025 huggingface dataset:
Accuracy in phase determination of LP electromagnetic seismographs based on transient calibration pulse
Authors: Mitronovas W.
Published: September 2021

abstract

A modification of the Jarosch and Curtis (1973) formulation for the calibration pulse inversion is suggested in an effort to improve its accuracy. The modification involves the introduction of the origin time of the pulse (time of the step in the calibration current) as an additional parameter to be solved in the least-squares inversion. This approach is found to be not completely satisfactory in general, but does improve the solution when a large error in origin time (> ±0.5 sec) is introduced in digitizing the pulse. A typical solution, when the origin time of the pulse has to be determined by least-squares, is accurate to within ± 1 sec in the phase response of a system for periods up to 500 sec. A more satisfactory approach is to record the origin time of calibration pulses on seismograms. Only a minor modification of the existing calibration circuit is necessary to provide a simultaneous signal to a time relay and calibration coil through a double pole switch. For pulses, where the origin time is known accurately, the existing techniques give results accurate to within ± 0.3 sec in phase response.
Rotation of footings due to surface waves
Authors: Stratta J. L. , Griswold T. F.
Published: September 2021

abstract

A possible failure mode for a column is presented. Surface waves could cause a spread footing to rotate failing the column at its base.
The identification of building structural systems
Authors: Udwadia Firdaus E. , Marmarelis Panos Z.
Published: September 2021

abstract

This paper investigates the response of structural systems to strong earthquake ground shaking by utilizing some concepts of system identification. After setting up a suitable system model, the Weiner technique of nonparametric identification has been introduced and its experimental applicability studied. The sources of error have been looked into and several new results have been presented on accuracy calculations stemming from the various assumptions in the Wiener technique.

The method has been applied in studying the response of a 9-story reinforced concrete structure to earthquake excitation as well as ambient vibration testing. The linear contribution to the total roof response during strong ground shaking has been identified, and it is shown that a marked nonlinear behavior is exhibited by the structure during the strong-motion portion of the excitation.
A physical basis for earthquakes based on the elastic rebound model
Authors: Ohnaka Mitiyasu
Published: September 2021

abstract

The elastic rebound model explaining seismological data quantitatively is derived by developing the original elastic rebound theory proposed by H. F. Reid. Assuming that the dislocation front propagates in one direction along the long axis of the fault plane, the shear strain drop Δɛ, the earthquake volume V, the stiffness of the fault, the mass of inertia, and the seismic energy radiated Es are evaluated in terms of the fault-plane dimensions, the dislocation D, the propagating velocity of dislocation v, and the Shear-wave velocity. The elastic strain energy released is evaluated in terms of V, Δɛ, and the initial shear strain. It is shown that the order of magnitude of Es is virtually given by μWD2, where μ is the rigidity and W is the fault width. The order of magnitude of the initial slip acceleration is estimated by making use of the formula derived in a previous paper. The moment of the elastic rebound force is calculated. The maximum amplitude of the far-field wave motion is in proportion to vM0/L, where M0 is the seismic moment and L is the fault length: this predicts that log (M0/L) is linearly related to the magnitude M, if v is assumed to be almost constant for actual earthquakes. The good linear relation, log (M0/L) = 1.2M + 11.7 (M0/L in dynes), is found empirically over a wide range of M (2 ≦ M ≦ 8.5). The directly proportional relationship between the logarithm of seismic moment per unit area and the magnitude seems to hold empirically.
Three-dimensional seismic structure of the lithosphere under Montana Lasa
Authors: Aki Keiiti , Christoffersson Anders , Husebye Eystein S.
Published: September 2021

abstract

Using P-wave residuals for teleseismic events observed at the Montana Large Aperture Seismic Array (LASA), we have determined the three-dimensional seismic structure of the lithosphere under the array to a depth of 140 km. The root-mean-square velocity fluctuation was found to be at least 3.2 per cent which may be compared to estimate of ca. 2 per cent based on the Chernov random medium theory. The solutions are given by both the generalized inverse and stochastic inverse methods in order to demonstrate the relative merit of different inversion techniques.

The most conspicuous feature of the lithosphere under LASA is a low-velocity anomaly in the central and northeast part of the array siting area with the N60°E trend and persisting from the upper crust to depths greater than 100 km. We interpret this low-velocity anomaly as a zone of weakness caused by faulting and shearing associated with the building of the Rocky Mountains.
A permanent seismograph array around the Gulf of California
Authors: Brune James N. , Lomnitz Cinna , Allen Clarence , Mooser Federico , Lehner Francis , Reyes Alfonso
Published: September 2021

abstract

A permanent seismographic array has been established around the Gulf of California. Solar-powered stations are operating at Caborca, Bahia de los Angeles, Guaymas, Topolobampo and La Paz. Trailer stations using local 60-cycle power are operating at San Felipe, Rio Hardy, Rancho Meling, and Ensenada. The array is unique in the following aspects: (1) It is the only array operating in close proximity to an active region of sea-floor spreading; (2) its sophisticated low-power design and use of solar energy made siting choices simpler so that local noise sources could be minimized; (3) it is the first accurately timed array to operate in northwest Mexico.

The array has already provided important information on seismicity in the Gulf of California and has aided in several sonobuoy studies of swarms and aftershock sequences. As more data accumulate, many of the important questions concerning the seismicity, tectonics, and structure of the Gulf of California will be answered.
The August 1975 Oroville earthquakes
Authors: Lahr K. M. , Lahr J. C. , Lindh A.G. , Bufe C. G. , Lester F. W.
Published: September 2021

abstract

On August 1, 1975, a magnitude 5.9 (mb) earthquake occurred approximately 8 km SSE of the town of Oroville, California. This earthquake and its associated foreshock-aftershock sequence are of particular interest because of their possible relation to the impounding of the 4.3 billion m3 Lake Oroville. Hypocenter locations for 336 aftershocks that occurred during August define a fault plane striking N3°E and dipping 60° to the west to a depth of 10 km. Dimensions of the epicentral area are approximately 7 km in an east-west direction by 15 km in a north-south direction. The fault plane passes beneath Oroville Dam at 5-km depth, and if projected up dip, would crop out beneath the reservoir to the east. The distribution in space and time of foreshocks and aftershocks suggests that rupture began at depth and progressed up dip and to the north and south.
Strong-motion earthquake accelerograms at Brawley, California: January 25, 1975
Authors: Johnson Dennis A. , Hanks Thomas C.
Published: September 2021

abstract

During the Brawley earthquake swarm of January–February, 1975, a single strong-motion accelerograph installed after the swarm began recorded 27 positively identified earthquakes in 14 hr, at hypocentral distances of approximately 5 km. Eight of these had magnitudes (ML) ≧ 3.5, and several had ML < 2.5; the instrument independently triggered 18 times. Peak accelerations in excess of 10 per cent g were obtained for five of the eight earthquakes with ML ≧ 3.5, and a peak acceleration of 25 per cent g was recorded for the largest event, ML = 4.3.
The far-field spectrum of the displacement generated by a sudden SH crack
Authors: Husseini Moujahed I.
Published: September 2021

abstract

The far-field spectrum of the displacement caused by a two-dimensional SH crack (antiplane shear crack) that appears suddenly over a strip of width 2R is obtained in terms of the elliptic cylinder Mathieu functions. The amplitude spectrum of the displacement exhibits the following four features in terms of the normalized frequency h (h = Rω/β where R is the half-width of the crack, ω is the circular frequency and β is the shear-wave velocity): (1) for h < 1 the amplitude spectrum behaves as h−1,2; (2) at h = 1 the amplitude spectrum has a corner frequency; (3) for h > 1 the amplitude spectrum behaves as h−2; (4) the azimuthal dependence of the amplitude is like sin θ.

The first result is a consequence of the infinite area occupied by the crack. The corner frequency at h = 1 is smaller than the value proposed in other studies (e.g., Brune, 1970; Randall, 1973), and this is attributed to the two-dimensional nature of the problem. The high-frequency falloff of h−2 is in agreement with the model of Brune (1970). The radiation pattern of sin θ is identical to that obtained by Burridge and Halliday (1971) for the same problem.
The effect of tectonic stress release on explosionP-wave signatures
Authors: Bache Thomas C.
Published: September 2021

abstract

The influence of induced tectonic stress release on the short-period teleseismic P-wave signature of underground nuclear explosions is studied. Primary attention is directed to the first few cycles of the record from which body-wave magnitude (mb) is determined. Computational models for both the explosion and the superimposed tectonic release double couple are employed and theoretical seismograms are computed. Interest is mainly in the largest tectonic release component that seems reasonable using surface-wave observations and independent estimates of the controlling parameters as constraints. It is concluded that for most, perhaps all, events, tectonic release has no appreciable effect on the amplitude of the short-period P waves. Even the frequency content of the early arriving P wave is little affected by tectonic release for most likely circumstances.

The computations assume tectonic release due to stress relaxation around the fracture zone created by the explosion. However, the results are extended to apply to the alternate mechanism whereby stress is released along a pre-existing fault plane. Since a number of other mechanisms can cause superposition of a double couple on the explosion, the analysis is relevant to the general question of the size these secondary sources must attain before the short-period P-wave recording is significantly altered.
Seismicity, gravity, and tectonics of northeast India and northern Burma
Authors: Verma R. K. , Mukhopadhyay Manoj , Ahluwalia M. S.
Published: September 2021

abstract

Practically the whole of northeastern India and northern Burma is characterized as an anomalous gravity field as well as an area of high seismicity. The Bouguer anomaly in the region varies from +44 mgals over Shillong Plateau to −255 mgals near North Lakhimpur in Assam Valley. Isostatic anomaly (Hayford) varies from +100 to −130 mgals in these areas. Over Arakan-Yoma and the Burmese plains, the isostatic anomalies vary from −20 mgals to −100 mgals.

Regions of high seismicity in the area include the eastern Himalaya (including Assam syntaxis), Arakan-Yoma including the folded belt of Tripura, Irrawaddy basin, Shillong Plateau, Dauki fault and the northern part of Bengal basin. The abnormal gravity and seismicity are related to large scale tectonic movements that have taken place in the area mostly during the Cretaceous and Cenozoic times, due to interaction of the Indian, Tibetan, and Burmese plates. The high seismicity indicates that the movements are continuing. The seismic zone underlying Burma is approximately V shaped and dips toward the east underneath Arakan-Yoma. Most of the intermediate-focus earthquakes in Burma underlie the area characterized by negative isostatic anomalies, indicating the probable existence of a subduction zone underneath the Arakan-Yoma and the Burmese plains.

The Shillong Plateau has a history of vertical uplift since Cretaceous times. Provided this statement is true, the uplift of the plateau preceded Himalayan tectonics starting 20 to 30 m.y. before continental India made solid contact with the Eurasian plate. The plateau is characterized by large positive isostatic anomalies as well as high seismicity. The positive isostatic anomalies may be due to intrusion or incorporation of basic material from the mantle into the crust underlying the Plateau. These intrusions may have taken place through deep seated faults such as the Dauki and could be responsible for its uplift as well.
Microearthquake survey of Tehran region, Iran
Authors: Hedayati A. , Brander J. L. , Berberian M.
Published: September 2021

abstract

A short microearthquake survey of part of north central Iran around the city of Tehran made late in 1974, showed that earthquakes occurred at the rate of 21.37 events per day.

Epicentral locations for 37 events, using a geometric ray path technique, show the observed activity to be concentrated in three principal groups: two associated with the known major fault on the south flank of the Alborz mountain, while the third constitutes a previously unrecognized lineation passing very close to the city of Tehran.

The cumulative number versus magnitude relation was obtained from the study of 198 well-recorded events. The slope of the linear portion of the relation (b value), −0.79, agrees well with the value of −0.86 determined from the USCGS records of larger earthquakes between 1961 and 1973.

Composite fault-plane solutions were made for each of the three principal groups, showing predominantly strike-slip movement with a thrust component on the south of the Alborz and thrusting on the new lineation.

The seismic intensity risk curve calculated for the area shows that the city of Tehran can expect ground movement of MM intensity VII every 12 years, and intensity IX every 350 years.
Intensities and travel times of seismic rays in a sphere with a linear velocity function
Authors: Odegard Mark E. , Fryer Gerard J.
Published: September 2021

Equations are presented which permit the calculation of distances, travel times and intensity ratios of seismic rays propagating through a spherical body with concentric layers having velocities which vary linearly with radius. In addition, a method is described which removes the infinite singularities in amplitude generated by second-order discontinuities in the velocity profile. Numerical calculations involving a reasonable upper mantle model show that the standard deviations of the errors for distance, travel time and intensity ratio are 0.0046°, 0.057 sec, and 0.04 dB, respectively. Computation time is short.
Time and magnitude relations for three microaftershock series near Hollister, California
Authors: Udías Agustín
Published: September 2021

Three series of aftershocks occurred in the region near Hollister, less than 15 km from the San Andreas Geophysical Observatory in 1968, 1970, and 1971 following shocks of magnitudes 2.3, 3.2, and 4.0, respectively. The high-gain system operating at SAO permitted a full study of these series for events as small as magnitude -0.7. The distribution of time intervals between consecutive shocks and magnitudes show certain definite differences in the time, space, and magnitude structure of the three sequences. The 1968 and 1970 series are highly concentrated in time and originate from quite small source volumes. Both correspond to the mainshock-after-shock type with high values of b (1.1 and 0.91). The 1971 series located in the Bear Valley area about 15 km south of the other two belongs to the swarm type with a low value of b (0.41). The situation suggests different physical conditions in two neighboring areas of the same fault with less homogeneous material and higher stresses acting at the area of the 1971 series. Variations in the b value with time for an area of 2500 km2 around SAO can be interpreted as due to migration of seismic sources from one area to another, or definite changes in rock properties with time.
A study of the strong ground motion of the Borrego Mountain, California, earthquake
Authors: Heaton Thomas H. , Helmberger Donald V.
Published: September 2021

Several synthetic models are constructed to fit the first 40 sec of the transversely polarized displacement, as recorded at El Centro, of the April 9, 1968 Borrego Mountain earthquake. The modeling is done in the time domain using the response computed for a distributed set of point shear dislocations embedded in a layered half-space. The beginning 10 sec of the observed record is used to model the spatial and temporal distribution of faulting whereas the remaining portion is used to determine the upper crustal structure based on surface-wave periodicity. A natural depth criterion was provided by comparing the amplitude of the direct arrival with the surface-wave excitations. Trade-offs are found to exist between source models and velocity structure models. Within the framework of a layer over a half-space model, faulting of finite vertical extent is required, whereas the horizontal dimensions of faulting are not resolvable. A model which is also consistent with the teleseismic results of Burdick and Mellman indicates massive faulting near a depth of 9 km with a fast rise time producing a 10-cm displacement pulse of 1 sec duration at El Centro. The faulting appears to slow down approaching the surface. The moment is calculated to be approximately 7 ×1025 dyne-cm which is somewhat smaller than the moment found by Burdick and Mellman (1976).
Amplitude-distance relation for 20-second Rayleigh waves
Authors: von Seggern David
Published: September 2021

Amplitude measurements on Rayleigh waves near a period of 20 sec were extracted from an 8-month data base for nine stations of the High-Gain Long-Period network. Application of an appropriate statistical model resulted in station, event, and distance terms; the distance terms defined a relation significantly different from the standard distance-dependent correction for Ms estimation. The apparent Q for 20-sec Rayleigh waves implied by this new data is roughly 700, in contrast to the 350 implied by the standard correction.
Seismic magnitude from Fourier analysis
Authors: Grant John A. , Mansinha L.
Published: September 2021

The inherent frequency dependence of the maximum peak-to-peak amplitude of seismograms suggests the use of Fourier analysis to calculate magnitudes. Since most magnitude scales use logarithms of amplitudes and amplitude/period ratios, the stability of the equivalent frequency-domain quantities was examined in a study of the spectra of Rayleigh waves from five earthquakes, a total of 73 records. The use of spectral amplitudes in formulas which were empirically developed for use with time-domain measurements resulted in smaller values of magnitude. Nevertheless, the two quantities were found to be linearly related. It was found that the use of the maximum Fourier amplitude resulted in the most stable spectral magnitudes with respect to epicentral distance and the time-domain magnitudes. This indicates that the maximum peak-to-peak amplitude of the time-series is not directly related to the Fourier amplitude at the same period, but rather to the maximum Fourier amplitude. Based on these 73 records for events with MS = 5.9 to MS = 6.7, we conclude that magnitudes may be determined from spectral measurements, with a marginal reduction in standard deviation over the time-domain formulas.
Spectral and magnitude characteristics of anomalous Eurasian earthquakes
Authors: Kim So Gu , Nuttli Otto W.
Published: September 2021

A number of main shock-aftershock sequences in the Eurasian interior contain some aftershocks whose mb:MS values are close to those of underground explosions. This paper is concerned with a study of the amplitude spectra of the P waves and Rayleigh waves for earthquakes of those main shock-aftershock sequences. It is found that for any given sequence studied, there is little if any variation in focal depth or focal mechanism. This rules out variations in these quantities as being the cause of anomalous mb:MS values. A study of the P-wave spectra establishes that one or both of the corner periods of anomalous earthquakes are smaller than those of non-anomalous earthquakes of the same moment. Thus the cause of anomalous mb:MS values of the earthquakes studied is a relative enrichment of the short-period portion of the spectrum of the anomalous events, which cannot be attributed to focal depth or focal mechanism.
Noise level variation at norsar and its effect on detectability
Authors: Ringdal F. , Bungum H.
Published: September 2021

For a 3-year period, noise level measurements of short- and long-period data at NORSAR have been sampled at hourly intervals. Significant seasonal fluctuations in noise level have been found, in particular for long-period data. The noise amplitude distribution is approximately lognormal for band-pass filtered short-period data in the P-wave detection band, while the long-period noise data show a skewness that cannot be represented by a lognormal distribution. Diurnal fluctuations in noise level are quite small, but definitely present both for short and horizontal component long-period data. Cultural sources are found to account for the short-period variability, while the long-period fluctuations are attributed to atmospheric pressure variation. Event detection performance generally follows the noise level trends, with an increase in the number of reported events during summer of about 50 per cent relative to winter.
Public Burdens in Situations of Constitutional Emergency
Authors: Konarski Marcin Jerzy
Published: September 2021

The aim of this article is to analyse issues related to extraordinary measures (martial law, a state of emergency or a state of natural disaster) provided for by the Polish Constitution. The subject of the research concerns the duty to provide personal and in-kind contributions (public burdens) in the event of the introduction of one of extraordinary measures. The author focused his attention on the nature of these contributions in relation to each of extraordinary measures, analysing their subjective and objective scope, the procedure, as well as the principles and mode of remuneration for and compensation of losses resulting from the duty to bear these burdens in situations of extraordinary measures.
Remoción de arsénico (III) en sistemas acuosos por adsorción utilizando sólidos naturales de Ecuador
Authors: San Martín Delly , Medina Daniel F , López Carmen Milena , Aguilar Silvio , García Luis V. , Guaya Diana
Published: September 2021

The aim of this work was to investigate the properties of two clays and a natural zeolite available in Ecuador, for the removal of Arsenic (III), (As (III)), in synthetic aqueous solutions. The adsorbents were prepared from the powdered solids, shaped as cylindrical extrudates of 0.5 cm in length by 0.2 cm in diameter approximately, and characterized by X-ray Diffraction (XRD), X-ray Fluorescence (FRX) and specific area ( Ae). Arsenic adsorption in aqueous systems was determined by charging load  experiments, using a dosage of 0.1 L of solution per grame of adsorbent, at 30 ° C in a stirred system (100 r. p. m.). The Arsenic content was determined by means of atomic absorption spectrophotometry with a hydride generator. The kinetics absorption was analyzed  by following the variation of the concentration of an 80 mg As/L solution, taken at different times for an extended period of 24 hours. The experimental data showed a good fit using a pseudo-first-order equation for the natural zeolite and pseudo-second-order equation for the two clays. The maximum adsorption capacity of As was higher for clays (13-15 ) compared to zeolite (5-6 ). These values are lower compared to those reported in the literature, however, the solids studied have the advantage of requiring a simple preparation process and they represent an abundant cheap raw material in the country.
Modelo multiobjetivo para la selección de estrategias óptimas de mantenimiento en sistemas multicomponentes: una aplicación en líneas de transmisión de energía eléctrica
Authors: Moronta Ramírez José Agustín , Rocco S. Claudio M.
Published: September 2021

A multi-objective model is proposed for defining optimal maintenance strategies, in systems composed of several interconnected elements. The optimal maintenance strategies derived correspond to a set of efficient actions, focused on maximizing the reliability of the system, and minimizing the associated costs. Optimization is carried out by using evolutionary algorithms type NSGA-II. For the evaluation of the system reliability, a procedure based on Monte Carlo simulation is used, which allows analyzing systems with different performance functions and for component configurations different from the classical ones (series, parallel, k-out-of-N). The proposal is applied to assess electrical power system components, specifically the insulator chains of the transmission lines. Several scenarios illustrate the proposed model. The strategies selected by the model prioritize the most important elements based on costs and/or maintenance. These strategies make up an approximate Pareto front, in which the decision-maker can choose the most suitable strategy according to their interests.
Hazard perception of novice drivers in mountain roads: a case study in Ecuador
Authors: García Ramírez Yasmany Damián , Cuenca Wendy
Published: September 2021

Novice drivers are more likely to be involved in a traffic accident than experienced drivers. Detecting danger is one of the skills that these drivers must acquire with age and experience. This can reduce this probability, especially on mountain roads. Therefore, the purpose of this research was to analyze the hazard perception of novice drivers on mountain roads. Thirty-seven drivers participated in the experiment, who watched videos of road sites. After each video, they had to answer a survey about the hazards they observed on the site. Based on this survey, the hazard perception was estimated, which was compared with the actual hazard, calculated by iRAP. As expected, drivers do not recognize hazards properly, especially in the most dangerous places. Nosignificant differences were found among sex, age, and type of driver's license. However, relationships were found among hazard perception, the actual hazard, and the error between them, so four linear equations were calibrated. This research will help public and private institutions related to road safety optimize resources in driver training by: a) including the hazard detection of danger in the curriculum, or b) offering a complementary course to those who have already obtained their license.
Aplicación de índices espectrales para determinar la transformación del bosque seco en Agua de Dios (Cundinamarca, Colombia)
Authors: Alarcón Montaña Angie Daniela , Rozo Arango Miguel Angel
Published: September 2021

The tropical dry forest (TDF), recognized for stabilizing soils and regulating the hydrological cycle, has been affected by the loss of plant vigour and substrate moisture, particularly in the municipality of Agua de Dios (Cundinamarca, Colombia) that presents one of the last relics of this biome. The study analyzed the transformation of TDF in this municipality for 1991, 2015 and 2020, through the calculation of the NDWI and NDVI of Landsat satellite images to establish the evolution of vegetable vigour and humidity of TDF. The main results show an increase in the low (between −0.6 and −0.1) and very low (from −1 to −0.61) categories of the indices, which leads to the conclusion that there is a decrease and correlation between them for both seasons (dry and rainy).
Simulación del comportamiento de la COVID-19 por medio de dinámica de sistemas en Bogotá D. C.
Authors: Gelves Alarcón Oscar Mauricio , Navarro Romero Elisa del Carmen
Published: September 2021

The pandemic caused by COVID-19 has been one of the most recent events that has affected human society in different social, economic, cultural and educational aspects. This document aims to design a continuous simulation model through the System Dynamics to define the behavior and evolution of the COVID-19 pandemic in the city of Bogotá DC. For this study, health data was taken regarding the number of infections and deaths during the year of pandemic, based on the theoretical models of Kermarck, SIC and the concepts of System Dynamics. The simulation model was development in the Vensim software. The results obtained by the simulation in a period of 24 months, a total of 993.421 infections were observed. Two scenarios are proposed with changes in the probability of contagion and the average interaction of people where it is validated that an increase in these factors accelerates the levels of infections and the number of deaths related to COVID-19.
Diseño de Rutas Escolares a través de un Modelo Heurístico programado en Visual Basic
Authors: Herrera Ochoa Oscar Javier , Bedoya Paula A. , Forero Andrés F
Published: September 2021

Nowadays, the effectiveness of transport management systems must not only provide an optimization of the evaluation indices of the system, but also, allows a much more dynamic and reliable control in the decision-making process. Thus, the present work studies an approach to design a routing model for operation logistics in school transport companies in Bogota, Colombia by means of an heuristic method as solution technique; such method is more flexible than the exact ones since it allows to incorporate difficult-to-model conditions. The Clarke and Wright algorithm, developed in Visual Basic, is the model utilized; here, it was applied as
Nowadays, the effectiveness of transport management systems must not only provide an optimization of the evaluation indices of the system, but also, allow a much more dynamic and reliable control in the decision-making process. Thus, the present work studies an approach to design a routing model for operation logistics in school transportation companies in Bogotá, Colombia by means of a heuristic method as a solution technique. Such method is more flexible than the exact ones since it allows to incorporate difficult-to-model conditions. The Clarke and Wright algorithm, developed in Visual Basic, is the model used which was applied as case study to the student pick-up and drop-off system in the company Trans 2000uno Ltda., in Bogotá. The implementation of the heuristic method shows significant differences compared to an optimization model. Even though there is a slight increase in traveled distances, total times decreased since high traffic paths are avoided.
Evaluación de la capacidad de transporte de caudales y sedimentos del drenaje transversal en una carretera montañosa en los Andes del Ecuador
Authors: Briceño-Briceño Edison , Oñate-Valdivieso Fernando , Oñate-Paladines Arianna
Published: September 2021

Drainage is essential to ensure the useful life of roads. Not only water circulates through the sewers, but also sediment that is carried by the flow, either as bottom drag or in suspension. Therefore, the sustainable design of culverts must allow the sediment transport associated with natural river systems. In the present work, 6 culverts located on a mountain road in the Andes of southern Ecuador were studied. The hydraulic capacity of each culvert was evaluated evacuating a peak flow with a 25-year return period using specialized software. Additionally, the criterion of the beginning of the movement of the sediments was applied to analyze the self-cleaning capacity of the culverts. After the evaluation, it was found that only three of the culverts studied had sufficient capacity to transport the evaluated flow and that all culverts had the necessary conditions to avoid the deposition of sediment.
Evaluación del desgaste de pavimento flexible mediante el uso de fotogrametría de corto alcance
Authors: Cango Mena Lauro Patricio , Zárate Torres Belizario Amador
Published: September 2021

This research articleanalyzes a new technique called Short Range Photogrammetry (FCA), to estimate the wear of the tread layer of flexible pavement in the Loja Catamayo road, by using a portable camera on a metal structure. The investigation evaluated the profiles of the Digital Elevation Models, in a millimeter way. Hence,with the difference in the profiles of the MDE and RMSE, it was possible to estimate the wear produced in a period not exceeding one month. The results were very encouraging since numerically it was found that the greatest wear occurred in the lane where there is a greater circulation of heavy vehicles. That is why the FCA method is valid to perform a periodic assessment of the condition of the flexible pavement tread.
Third Space Creates Collaborative Environments to Develop Pre-service Teachers
Authors: Steiner Amanda , Bell Julie , Wilcoxen Christina
Published: September 2021

In the fall of 2012, 11% (n=157) of clinical practice (i.e. student teaching) candidates at a metropolitan university were in jeopardy of not passing clinical practice. Public schools in the area began to voice their concerns, and placements of candidates became a challenge. As a result, the university re-envisioned the program, utilizing third space to facilitate discourse between local school districts and university faculty. The development of third space was based on program data, which led to the following shifts in the program: scaffolded coursework with increased time in the field; instructional coaching prior to clinical practice; and a system for collecting feedback to sustain partnerships. Collaboration between P-12 schools and the university was essential in preparing candidates to connect theory and apply it in practice. By spring 2016, the initiatives implemented led to a 12% decrease of candidates in jeopardy of not passing clinical practice. As the teacher preparation program continues to grow, one of the biggest challenges is continuing to build and sustain new partnerships. The authors provide a framework for how programs could adapt some of these initiatives to develop and sustain university and school partnerships.
Effects of Teaching in a Summer STEM Camp on the Mathematics Teaching Self-efficacy of Highly Qualified Preservice Secondary Mathematics Teachers
Authors: Franks Bridget , McGlamery Sheryl
Published: September 2021

Educational opportunity gaps experienced by students of color living in poverty, with accompanying lower levels of mathematics achievement, remain a roadblock to their access to college-level training in STEM fields. To address this problem, secondary teachers must be confident in their ability to share mathematics content effectively with students from cultures different than their own. Bridging the opportunity gap is more likely with two elements in place: intellectually stimulating pre-college experiences and community partnerships that establish connections between underserved neighborhoods and resource-filled environments such as university campuses.
This study explored the effects of teaching in a four-week STEM summer camp for ethnically diverse, high-needs middle school girls on the teaching self-efficacy of highly-qualified preservice secondary mathematics teachers, a group that has been less studied than preservice elementary teachers. Participants were scholarship students in a federally-funded teacher preparation scholarship program at an urban, metropolitan university. Teaching self-efficacy was measured by the Mathematics Teaching Efficacy Belief Instrument (MTEBI) and by follow-up qualitative analysis of questionnaire responses and focus groups. Participants’ gains on the MTEBI were significant for Personal Mathematics Teaching Efficacy, but not for Mathematics Teaching Outcome Expectancy. Qualitative analyses suggested that both instructional coaching and everyday interactions in a summer camp setting contributed strongly to the preservice teachers’ increased confidence about teaching mathematics to culturally diverse, high-needs learners.
An Exploratory Study of the Community Impacts of Service-Learning
Authors: Lau Ka Hing , Chan Maureen Yin Lee , Yeung Cynthia Lok Sum , Snell Robin Stanley
Published: September 2021

Research on community impacts from service-learning has been scarce, yet this area is worth exploring in order to understand how and why service-learning can make a difference. The current research sought to validate a conceptual framework (Lau & Snell, 2020), which categorizes the impacts of service-learning on community partner organizations (CPOs) and on end-beneficiaries. Under the framework, impacts on end-beneficiaries can arise directly from service-learning interventions, but can also arise indirectly as a result of impacts on CPOs. For the research, semi-structured, one-to-one or focus group interviews were conducted with 13 CPO representatives, seeking their perceptions of positive and negative impacts of service-learning. Most described impacts were positive, including, for CPOs: achieving project goals to further the CPO’s mission; augmenting resources of the CPO; and gaining knowledge, insights, ideas and techniques. These positive impacts for CPOs appear to reflect three factors: alignment between service-learning project goals and the CPO’s mission; mutual recognition of students’ potential for transferring knowledge from universities to CPOs; and mutual understanding of students’ status as semi-outsiders, free to challenge existing practices or systems. Further studies can explore impacts from the end-beneficiary's perspective, and adopt longitudinal and action research approaches.
An Analysis of Product Dimensions Out of Specification as Quality Claim Improvement Activity : Application of 8D Method in the Injection Plastic Industry
Authors: Lubas Wahyudi Pongky , Wulandari Anita
Published: September 2021

Every company tries to find ways to maintain its market position in an increasingly competitive business environment. In order to be successful, companies need to achieve their objectives and goals to make their vision a reality while adhering to their mission. Company claims report in the few years still hasn’t solved yet. Such complaints are significant because customersatisfaction can only be improved if the root causes of the problem is clearly identified. In the plastic industry that produces parts for the automotive industry, a systematic method named 8D is used to analyze product conformity to specifications. The 8D method consists of nine disciplines problem-solving. The original purpose of 8D method was to eliminate the defect causing the problem, thus restoring customer satisfaction and level up the quality level of the company. This research established the suitability of the 8D for complaint settlement. 8D involves teamwork to solve the problem and using a 9-step structural approach. This case study resulted that the 8D is effective. The total customer claims at the end of last year until this year in Dec 2020 totaled zero (0) and process rejection for incorrect dimensions were reduced from 0.07 % to 0.01%.
Response of Growth and Yield of Soybean (Glycine max l. Merril) to the Method and Dose of Leachate Liquid Organic Fertilizer Application
Authors: Hasnelly Hasnelly , Yasin Syafrimen , Agustian Agustian , Darmawan Darmawan
Published: September 2021

The high demand for soybeans cannot yet be met by domestic production. Thus, a way to increase soybean production is necessary, one of which is to use liquid organic fertilizer derived from landfill leachate. This study aimed to examine the application method of liquid organic fertilizer (LOF) from landfill leachate to the soil and leaves and to determine the concentration giving the best growth and yield of soybean plants. The study was a field-research arranged in a completely randomized design (CRD) consisting of six treatments and four replications, which was carried out in a greenhouse. The treatments include A (0 LOF/L water), B (20 ml LOF/L water), C (30 ml LOF/L water, D (40 ml LOF/L water), E (50 ml LOF/L water) and F (60 ml LOF/L water). The liquid organic fertilizer was applied through the soil and leaves at a dose according to the treatments.  The results showed that the application of liquid organic fertilizer from landfill leachate was better applied to the soil than to the leaves. The liquid organic fertilizer given had a significant effect on the leaf area (cm2), crop weight (g), and plant seed weight (g), but not on the plant height (cm) and stem diameter (cm). Liquid organic fertilizer application is better given to the soil than to the leaves based on the independent T test. The liquid organic fertilizer from landfill leachate at a concentration of 40 ml/L of water had the best effect on the growth and yield of soybean plants.
The Potential of Biogas Slurry and Palm Oil Mill Effluent Slurry as Slow-Release Fertilizer Pellet Through Densification
Authors: Widyowanti Reni Astuti , Ginting Candra , Renjani Rengga Arnalis
Published: September 2021

Organic fertilizer can yield higher production compared to regular fertilizer if properly applied. Thus, it can be a solution to improve nutrient content of soil. The biggest source of bio slurry in plantation is from Palm Oil Mill Effluent (POME) and cow dung biogas. This research aimed to analyze the residue’s potential from the result of biogas processing and bio slurry from POME as slow-release fertilizer pellet. Bio slurry was processed into pellet through densification process using pellet mill. The research was arranged in a Randomized Block Design method with five slurry compositions as treatments, including 70:30, 60:40, 50:50, 40:60, and 30:70 (ratio of biogas slurry and POME slurry), each consisted of three replications. According to the data obtained, fertilizer pellets had characteristics of 25 – 29 mm of length, 5.23 – 5.85 mm of diameter, 0.44 – 0.53 g/cm3 of density, 54.78% - 81.96% of durability, and 7.81% - 8.57% of moisture content. Based on density and durability aspects, 30:70 composition was the higher. Macronutrient content of the five compositions were 1.88% - 2.72%, in which on day 22, N, P, and K release was 0.36 – 1.01%, 73.51 – 97.48%, and 3.19 – 7.85%, respectively. Meanwhile, on day 17, the nutrition solution conductivity of all compositions had already reached 0.80 – 1 mS/cm.
The modern level of catalysts and technologies for natural gas conversion to syngas
Authors: Pinaeva L. G. , Noskov A. S.
Published: September 2021

The paper presents an analysis of the main catalysts and technologies applied for industrial conversion of natural gas to syngas, which is further used to produce ammonia, methanol and hydrogen. The analysis reveals the major trends in their development aimed to reduce the consumption of energy and resources; technological schemes of the processes as well as the catalysts and sorbents used in different steps of methane reforming and steam conversion of CO are described.
Pre-scaling up of improved faba bean technologies in the highland districts of Guji Zone, Oromia regional state, Ethiopia
Authors: Kebede Basha , Korji Dembi
Published: September 2021

Pre scaling up of Gebelcho and Walki was conducted in the highland districts of Guji Zone during 2014/15-2015/16 year to increase farmers’ capacity in production and management practices of faba bean. Two kebeles from each two districts namely Bore and Ana Sora were selected purposively based on their potential for faba bean production. From each kebele nine farmers were selected for the activity making it a total of 72 farmers for the two years. Depending on the capacity of farmers 50kg-100kg of faba bean was given for the selected farmers. Around 24.5ha was covered by the crop during the production years. Training was also given for participating farmers and others on production packages of faba bean. Exchange visits and mini field days were arranged for further promotion. The yield gained from the varieties was 33.76qt/ha and 27qt/ha from Gebelcho and Walki respectively. Both varieties were found to be acceptable during field days by farmers due to their disease tolerant capacity. Thus, highland farmers are recommended to use Gebelcho and Walki varieties to increase faba bean production and generate income for their livelihood. Further dissemination of faba bean is expected from seed multipliers in producing quality seed and addressing potential areas.
Demonstration of improved teff varieties at selected midland districts of Guji zone, Oromia regional state, Ethiopia
Authors: Kebede Basha , Korji Dembi
Published: September 2021

The activity was conducted during 2014 and 2015/16 year at Adola Rede and Ana Sora districts, Guji zone to evaluate the performance of improved teff varieties along with management practices under farmers’ circumstances and to raise farmers’ knowledge and skill on improved teff production and management practices. Two improved teff varieties (Tseday and Boset) were demonstrated along with local varieties. Sites were selected with respective district agricultural offices based on the potential of the area for teff production. Training was given for farmers, Development Agents and experts on teff production. The Participating farmers were also capacitated through training, follow up, exchange visits and mini field days. According to the results, the two improved teff varieties demonstration showed better yield performance when compared to the local variety. Thus, farmers in the area should use Tseday and Boset variety in order to increase their teff production and productivity.
Influence of salinity levels on vegetative development of landrace dwarf common bean (Phaseolus vulgaris L.) Genotypes
Authors: Ulukapi Kamile , Aydinsakir Köksal
Published: September 2021

In this study, plant growth parameters of 16 landrace dwarf common bean genotypes collected from Western Mediterranean region of Turkey at different salinity levels were investigated. The salt concentrations were applied 0.5 (regular irrigation water), 2, 4 and 6 dSm-1. The study continued until the first flowering was observed in the plants. The results of analysis of the variance revealed significant variations among different salinity levels, genotypes and interaction effects of salinity levels × genotypes for morphological characters. According to statistical analysis results, there was no correlation between stem diameter and other morphological characters. It was determined that there was a statistically significant positive strong correlation between plant height and plant dry weight (r=0.703). There was a moderately statistically significant positive correlation between all other characters. The increased salinity level negatively affected the vegetative growth of the common bean genotypes. However, low doses of salt have promoted development in some genotypes (AGB10, AGUN25, BY4, BY24, IYOZ10). However, a slight increase in salt level caused a sudden drop in development. These genotypes are thought to be suitable for soils with low salinity. The genotypes gave different responses to salt stress and ISGA1 and ISGA10 genotypes gave the best results. Besides them, prominent genotypes were detected as AGUN6, BKARA2, AGB10 and IYOZ10.