bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing SDG indicator 6.4.2 “level of water stress” at major basins level
Authors: Biancalani Riccardo , Marinelli Michela
Published: August 2021

This paper describes a method to disaggregate the indicator 6.4.2 (level of water stress) by major river basin. The analysis was performed using the GlobWat soil water balance model and global geospatial data consistent with national statistics published in AQUASTAT, the FAO’s global information system on water and agriculture. When a river basin spans across more than one country, the water stress calculated by country can be very different from that calculated by river basin since the counting of the renewable freshwater resources from one country to another is highly dependent on the official agreement and treaties that regulate the flow of those resources between countries. This problem is hydrologically solved once the accounting of the water resources is done on the major river basin as a whole. The disaggregation by river basin allows the identification of hotspots where actions should be prioritized and reveals that the area affected by a high or critical water stress spans across all continents with the exception of Oceania. It offers also the possibility of an analysis of freshwater withdrawals by sector, which may become crucial for the definition of water management policies in the context of the economic development of a country.
Thermal Stability and Tribological Behaviors of Tri-fillers Reinforced Epoxy Hybrid Composites
Authors: Sathishkumar Tottyeapalayam Palanisamy , Navaneethakrishnan Palanisamy , Maheskumar Ponnuswamy
Published: August 2021

The present works investigates the thermal stability and wear behaviour of tri-fillers reinforced hybrid composites. The Silica (S), Coconut shell (C) and Graphite (G) fillers reinforced homogeneous and functional graded epoxy composites are prepared by vertical injection molding techniques. The effect of filler contents, design parameters and its interaction on wear and friction behavior of SCG composites has been investigated. With help of Taguchi’s techniques, L27 orthogonal array, a series of experiments are planned and conducted on pin-on-disc tribo machine with three different loading of 10, 20 and 30 N, three sliding velocities of 1, 1.5 and 2 m/s by varying the G filler content of 10, 20 and 30 wt.% with constant weight fraction of S and C fillers of 10 wt.%. The results shows that the increasing the Gr content was increased the wear resistance and rate. The optimization techniques used to pridicated the composites parameters.
Pattern Recognition Algorithm for Automatic Quantification of Toxoplasma gondii Tachyzoites
Authors: Murcia Zapata Karen Nataly , Romero Cerón María Paula , Juez Castillo Graciela , Valencia Vidal Brayan Alfonso
Published: August 2021

Context: Digital image processing is an efficient and suitable computational tool for the automatic quantification of human pathogens in images, providing analysis in less time, greater number of samples, and result reproducibility. We propose the development and validation of an image processing algorithm, for the recognition and automatic quantification of T. gondii tachyzoites.
Method: We developed an algorithm based on image processing. This workflow allows identifying the morphology of each parasite in the image by determining the number of parasites distinguishing them from those with a similar morphology, but not corresponding to the parasite in question. Images were obtained through Giemsa staining protocols.
Results: The original images were analyzed by experts. The results showed correlation with those obtained by the automatic count. Additionally, a processing time of 5 seconds per image was obtained with the algorithm. This automated quantification tool allowed count of tachyzoites in tens of images.
Conclusions: This automatic image analysis tool can extend its implementation to any laboratory that is involved in the quantification of extracellular Toxoplasma gondii tachyzoites, as well as other aspects of research on its tachyzoites that require the count of this form of development of the parasite.
SOCIAL MEDIA NETWORKING AND COLLABORATING LEARNING AS CORRELATES OF PRINCIPALS' PERFORMANCE IN PUBLIC SECONDARY SCHOOLS IN DELTA STATE, NIGERIA
Authors: Ebunu A. A. , ONYEIKE DR. V. C.
Published: August 2021

This study examined the relationship between social media networking, collaborating learning and principals' performance in public secondary schools in Delta State. Two research questions guided the study. Two hypotheses were also tested in the study at 0.05 significant level. The study adopted the correlation design. The study population was the 427 principals in public secondary schools in Delta State Post-Primary Education Board. The sample size was 342 principals serving in public secondary schools in Delta State. The multistage sampling technique was used to select the sample. The instruments used to generate data were two questionnaires social media networking, collaborating learning and principals' performance, with reliability coefficients of 0.96 and 0.89 (SMNCL) and (PPQ). The generated data were analyzed using Pearson r and simple regression, t-test associated with simple regression. The findings of the study revealed that social media networking had a positive and strong relationship with principals' performance. The study also revealed that collaborative learning was significantly related to principals' performance in public secondary schools in Delta State. The recommendations made included school principals exploring social media as a veritable avenue for connecting and learning in different experts in different social media tools and online academic community.  The study also recommended that principals should maximize the benefits of teamwork, collaboration, and knowledge synergy with their professional colleagues as a pathway to improving their school leadership skills and competencies.
Beyond Rational Systems: Managing Organizational Conflicts From Pluralistic, Open Systems and Stakeholder Perspectives
Authors: IYAMABHOR Martins , OGBOR John, O. , AWOSIGHO Onome Precious
Published: August 2021

This paper examines organizational conflict in the context of rationalist, pluralist, open systems and stakeholder approaches. It argues that the prevailing rational and unitary approaches which dominate organizational analysis are inadequate theoretical tools for understanding the dynamics of organizational conflicts in a pluralistic society. Methodologically, the research approach is built on   meta-synthesis. A meta-synthesis is a research approach that brings together qualitative data to form a new interpretation of a research field.  From this approach, the paper critically examines three of the dominant approaches in organizational theorizing (the rational, pluralist and open systems perspectives) and their implications for understanding and managing organizational conflict. A synthesis of the literature combines the three perspectives to propose a framework for managing conflicts in organizations. The paper suggests that the open system perspective, in line with a pluralist perspective, is an appropriate framework for studying the relationship between stakeholder management and conflict management and for understanding the dynamics and the forces shaping conflicts in organizations. A stakeholder approach for understanding interests and sources of organizational conflicts is presented including stakeholders’ sources of power and legitimacy. Finally, a framework encompassing strategies for managing organizational conflicts by applying principles of stakeholder management are suggested.
Firm Characteristics, Financing and Firm Innovation in Africa
Authors: Asiedu Michael
Published: August 2021

The study employed firm level data from the World Bank’s Enterprise Survey Indicator Database to investigate firm characteristics associated with firm innovation in 32 African countries, for the period 2009 to 2018. We find that firm level innovation, including the introduction of significantly new products (H1), new or significantly improved methods of manufacturing products (New Technology) are strongly associated with external funding sources (funds from Banks and non-banking institutions). In addition, firm level characteristics such as firm age, female ownership, capacity utilization, educated labor force, exposure to competition is strongly associated with firm innovation. These findings are very important for countries in Africa (and other less-developed countries) who spend less on research and development due financing and structural constraints but want to accelerate economic growth and increased productivity.
Physical and Mental Health Effects of Characteristics of Caregivers and the Caregiving Situation
Authors: Son Chong-Hwan
Published: August 2021

The present study investigated the effects of characteristics of caregivers and the caregiving situation on family caregivers’ physical/mental health, using the multiple regression analysis with the time-series and cross-sectional data from the 2015-2018 Behavioral Risk Factor Surveillance System (BRFSS). The regression results indicated that the caregiving role could increase the risk of developing physical/mental health problems. Importantly, this study revealed that the characteristics of caregivers and care recipients were significantly associated with caregivers’ physical/mental health outcomes. Especially the results showed that the caregiver support program was the most significant factor linked to caregivers’ physical/mental health. It pointed to the importance of caregiver education and support programs for family caregivers to cope with the stress from providing care or daily assistance. The results also pinpointed which area of support services for informal caregivers would be a priority to enhance. Thus, the public health policymakers should re-evaluate the current long-term care program to establish a more effective caregiving structure, especially caregiver education and support programs for family caregivers, to improve the informal caregivers’ quality of life.
Serological diagnostic for SARS-CoV-2: an experimental External Quality Assessment Scheme
Authors: Sciacovelli Laura , Padoan Andrea , Secchiero Sandra , Plebani Mario
Published: August 2021

Objectives

Numerous analytical systems, rapidly made available on the market throughout the SARS-CoV-2 pandemic, aim to detect COVID-19, and to continuously update and improve the same systems. Medical laboratory professionals have also developed in-house analytical procedures in order to satisfy the enormous volume of requests for tests. These developments have highlighted the need control the analytical procedures used in order to guarantee patient safety. The External Quality Assessment (EQA) Scheme, an important quality assurance tool, aims to guarantee high standard performance for laboratory and analytical procedures. The aim of the present study was to report on the results collected in an experimental EQA scheme for the serological diagnosis of SARS-CoV-2.

Methods

All qualitative results collected in the different EQA surveys were summarized in order to identify the percentage of laboratory results in relation to typology of antibodies, results and samples.

Results

A total of 4,867 data sets were collected. The analysis of EQA data made, demonstrates a better agreement among laboratories results for total Ig than single immunoglobulins (IgG, IgM, IgA) in the case samples positive for SARS-CoV-2, and a wide divergence between IgM results for positive samples (only 34.9% were correct). Results for negative controls and specificity controls demonstrated a better overall agreement than results for positive samples.

Conclusions

Working in collaboration with the IVD manufacturers, laboratory professionals must strive to achieve harmonization of results, and to develop well-defined protocols complying with the ISO 15189 requirements.
Analysis on space transmission model of the Microwave Wireless Power Transfer system
Authors: Peng Cheng , Ye Zhi-Hao , Xia Yi-Hui , Yang Chao
Published: August 2021

This paper systematically analyzes the main link that imposes restrictions on the overall efficiency of the Microwave Wireless Power Transfer (MWPT) system–space transmission. Three typical transmission models of aperture transmission in the near-field area, radiation-focused transmission in the middle-field area, and Friis transmission in the far-field area of radiation were analyzed and calculated. Then, the applicable conditions and efficiency of three-models were compared. And the influence of antenna electrical parameters on the efficiency of the MWPT system was discussed. In the end, three typical space transmission models of aerial vehicles, satellites, and islands were studied. The influence of the medium on the transmission efficiency was emphatically analyzed. This paper aims to summarize the general laws of space transmission of microwave energy. Provide a theoretical reference for related scientific research and engineering practice.
Evaluation of relative performance of Indian states in PV resource utilization through MPI
Authors: Yadav Vinod Kumar , Goyal Preeti , Thukral Arshiya , Varshney Nandni , Ghosh Santosh
Published: August 2021

To participate in the global fight against climate change, India has set an aggressive target of installing 100 GW of photovoltaic (PV) energy resources by 2022. However, only about 37% of this target is achieved till date, and, presently, the set target appears to be elusive. Hence it is crucial and the need of the hour to analyze the performance of different utilities to identify the regions that need a course correction. In the present work, the relative performance of the Indian states in realizing the national target of PV installed capacity is analyzed through the Data Envelopment Analysis (DEA) model. Time series analysis of the PV sector’s growth in different Indian states over the period 2017–2021 is quantified through the Malmquist productivity index (MPI). The applied methodology revealed that Rajasthan, which has the highest PV potential and second-highest PV installed capacity, is less productive than the small hilly states and union territories, which have meager PV potential. The result provides insight into the factors contributing to the inefficiencies in the development of the PV energy sector, which will help the policymakers take necessary corrective actions to improve the states’ productivity and thereby contribute more effectively to the national goal. The work may be extended to other regions of the world to strengthen the global effort to fight climate change.
Predication of negative dispersion for photonic crystal fiber using extreme learning machine
Authors: Vyas Ajay Kumar , Dhiman Harsh S.
Published: August 2021

The photonic crystal fiber (PCF) is a resourceful optical device that can be used in various applications. The dispersion is a major impediment for such optical waveguides. We propose a modified PCF that evaluates the negative dispersion coefficient−3126 ps/(nm–km) at 1.55 μm wavelength. The precise value calculation of the design parameters is helpful to improve the desired output. The machine learning approaches are now more in fashion to predicate such parameters. The dispersion parameters are obtained for three different PCF models as conventional PCF with fixed radius air holes and type 1 and type 2 models with dual radius air holes. Further, the negative dispersion of a type-I PCF is modeled using an extreme learning machine (ELM) as a regression task and its performance is tested against benchmark models such as support vector machine with linear and radial basis function kernel function, Gaussian process regression, and artificial neural network. Results indicate superior performance of ELM as a regressor both, in terms of prediction and computation time.
The Monetary Crisis of Lebanon
Authors: Bitar Joseph
Published: August 2021

Above its traditional currency and debt crisis features, Lebanon’s ongoing crisis sheds the light on the inherent weakness of dollarized monetary systems. This crisis can be seen as a monetary crisis, as the country’s dollarized banking system’s liquidity and solvency problems led to the loss of the “moneyness” of its dollar denominated deposits. We analyze the different dimensions of this crisis and we make policy recommendations, inspired by the experience of the Argentine 2001–2002 convertibility crisis. Finally, we look into the redistributive implications of different conversion scenarios.
OCD in the time of COVID-19: A global pandemic's impact on mental health patients and their treatment providers
Authors: Pinciotti Caitlin M. , Piacsek Kelly , Kay Brian , Bailey Brenda , Riemann Bradley C.
Published: August 2021

Individuals with obsessive-compulsive disorder (OCD) have evidenced resilience against large-scale crises, although emerging research on the impact of COVID-19 is mixed. Little is known about the impact of COVID-19 on mental health providers. Items from an instrument evaluating the impact of the September 11, 2001, terrorist attack were adapted to measure the impact of COVID-19 on emotions, cognitions, and behaviors. Using a sample of 65 patients with primary OCD diagnoses and OCD treatment providers in intensive programs for OCD and anxiety, the authors found that COVID-19 evidenced a less significant overall impact on patients than providers. Specifically, providers reported more significant impact on the amount of time spent worrying about COVID-19, taking additional cleaning and sanitization precautions, and time spent socializing with loved ones. Findings support previous literature indicating that individuals with OCD demonstrate resilience to large-scale crises, and offer insights into the specific struggles of providers who treat OCD.
Efficacy and Renal Tolerability of Ultrafiltration in Acute Decompensated Heart Failure: A Meta-analysis and Systematic Review of 19 Randomized Controlled Trials
Authors: Liu Yajie , Yuan Xin
Published: August 2021

Background: Acute decompensated heart failure (ADHF) is a life-threatening and costly disease. Controversy remains regarding the efficacy and renal tolerability of ultrafiltration for treating ADHF. We therefore performed this meta-analysis to evaluate this clinical issue.

Methods: A search of PubMed, EMBASE, and the Cochrane database of controlled trials was performed from inception to March 2021 for relevant randomized controlled trials. The quality of the included trials and outcomes was evaluated with the use of the risk of bias assessment tool and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach, respectively. The risk ratio and the standardized mean difference (SMD) or weighted mean difference (WMD) were computed and pooled with fixed-effects or random-effects models.

Results: This meta-analysis included 19 studies involving 1281 patients. Ultrafiltration was superior to the control treatments for weight loss (WMD 1.24 kg, 95% confidence interval [CI] 0.38–2.09 kg, P=0.004) and fluid removal (WMD 1.55 L, 95% CI 0.51–2.59 l, P=0.003) and was associated with a significant increase in serum creatinine level compared with the control treatments (SMD 0.15 mg/dL, 95% CI 0.00–0.30 mg/dL, P=0.04). However, no significant effects were found for serum N-terminal prohormone of brain natriuretic peptide level, length of hospital stay, all-cause mortality, or all-cause rehospitalization in the ultrafiltration group.

Conclusions: The use of ultrafiltration in patients with ADHF is superior to the use of the control treatments for weight loss and fluid removal, but has adverse renal effects and lacks significant effects on long-term prognosis, indicating that this approach to decongestion in ADHF patients is efficient for fluid management but less safe renally.
Using Modeling to Develop a Deep Understanding of Photosynthesis & Cellular Respiration as Chemical Processes
Authors: Hofeld Jennifer Ferguson
Published: August 2021

Photosynthesis and cellular respiration are core concepts in high school biology, as they are at the core of all living things. However, perhaps because students can’t see them happening, they very often have difficulty understanding them. Further, students often come into biology with a limited understanding of the law of conservation of matter as it relates to chemical reactions. These problems compound to create a great deal of misconceptions about these two important processes. In these lessons, I implemented the use of modeling to overcome these misconceptions and give my students a firm understanding of chemical equations, photosynthesis, and cellular respiration.
Prolonged Hyperbilirubinemia after Contrast Use in a 16-Year-Old Boy with Gilbert's Syndrome: A Case Report and Literature Review
Authors: Shin Woochul , Shin Suk Pyo , Han Sang Hak , Yoo Jung Kyung
Published: August 2021

This paper reports a child with Gilbert's syndrome who underwent cholecystectomy and endoscopic retrograde cholangiopancreatography, magnetic resonance cholangiopancreaticography to removal of the gallstones, then experienced increase in bilirubin of unknown cause.
Urbanalia jako propozycja genologiczna w ramach humanistycznych studiów miejskich
Authors:   Kolegium Literaturoznawstwa, Wydział Filologiczny, Uniwersytet w Białymstoku, Konończuk Elżbieta
Published: August 2021

The article discusses the idea of urban genres as forms of textualization of urban spaces, as proposed by Katarzyna Szalewska in her book Urbanalia – miasto i jego teksty: Humanistyczne studia miejskie (Gdańsk 2017). The proposed category of ‘urbanalia’ describes the urban genological land scape that comprises verbal and non-verbal utterances. Szalewska redefines such urban genres as passage, anecdote, spacerownik, urban legend, faits divers, picture, physiology, and tableaux, thus completing the urban studies with the literary methodology. In addition, the forms described by the author are characterized by high artistic and folkloristic qualities.
Metabolism-driven post-translational modifications of H3K9 in early bovine embryos
Authors: Ispada Jessica , da Fonseca Junior Aldcejam Martins , Santos Otávio Luiz Ramos , Bruna de Lima Camila , dos Santos Erika Cristina , da Silva Vinicius Lourenço , Almeida Fernanda Nascimento , de Castro Leite Saul , Juan Ross Pablo , Milazzotto Marcella Pecora
Published: August 2021

Metabolic and molecular profiles were reported as different for bovine embryos with distinct kinetics during the first cleavages. In this study, we used this same developmental model (fast vs slow) to determine if the relationship between metabolism and developmental kinetics affects the levels of acetylation or tri-methylation at histone H3 lysine 9 (H3K9ac and H3K9me3, respectively). Fast and slow developing embryos presented different levels of H3K9ac and H3K9me3 from the earliest stages of development (40 and 96 hpi) and up to the blastocyst stage. For H3K9me3, both groups of embryos presented a wave of demethylation and de novo methylation, although it was more pronounced in fast than slow embryos, resulting in blastocysts with higher levels of this mark. The H3K9ac reprogramming profile was distinct between kinetics groups. While slow embryos presented a wave of deacetylation, followed by an increase in this mark at the blastocyst stage, fast embryos reduced this mark throughout all the developmental stages studied. H3K9me3 differences corresponded to writer and eraser transcript levels, while H3K9ac patterns were explained by metabolism-related gene expression. To verify if metabolic differences could alter levels of H3K9ac, embryos were cultured with sodium-iodoacetate (IA) or dichloroacetate (DCA) to disrupt the glycolytic pathway or increase acetyl-CoA production, respectively. IA reduced H3K9ac while DCA increased H3K9ac in blastocysts. Concluding, H3K9me3 and H3K9ac patterns differ between embryos with different kinetics, the second one explained by metabolic pathways involved in acetyl-CoA production. So far, this is the first study demonstrating a relationship between metabolic differences and histone post-translational modifications in bovine embryos.
Effects of UV light irradiation on color changes in thermally modified rubber wood based on FTIR
Authors: Li Xiaowen , Li Tongtong , Li Guanjun , Li Min , Lu Quanji , Qin Shaoshan , Li Jianing
Published: August 2021

To evaluate the effects of chemical changes during thermal modification on the resistance of wood against photodegradation, heat-treated specimens of rubber wood (Hevea brasiliensis) were exposed to ultraviolet light for 384 h. The color changes in the exposed wood surfaces were analyzed using a colorimeter; the chemical changes were monitored using Fourier-transform infrared spectroscopy (FTIR). The photoweathering performances of rubber wood treated at 155 °C for 2 h, 155 °C for 6 h, and 185 °C for 2 h were similar to that of untreated wood, as the lignin did not undergo profound chemical transformation under mild modification conditions. However, compared to untreated rubber wood, the photoaging performances of rubber wood treated at 185 °C for 6 h and 215 °C for 2 h were notably changed. The transformation process was confirmed by FTIR. A good linear relationship between color change and lignin degradation was observed after mild, but not severe, heat treatment. The concentration of carbonyl groups in the wood specimens generally increased during photoaging, although not all samples showed a good correlation between color change and the concentration of carbonyl groups. Only the photochromic performance of wood changed notably when lignin was extensively modified under severe heat-treatment conditions.
Bacterial and mold resistance of selected tropical wood species
Authors: Reinprecht Ladislav , Vidholdová Zuzana , Iždinský Ján
Published: August 2021

The biological resistance of 21 tropical wood species against bacteria and molds was studied. The gram-positive bacterium Staphylococcus aureus and the gram-negative bacterium Escherichia coli had none or negligible activity on surfaces of zebrano and maçaranduba (up to 1 ×106 CFU/mL), and they had negligible or medium activity on surfaces of macassar ebony, ovengol, santos rosewood, and iroko (from 1 ×106 up to 1 ×107 CFU/mL). These bacteria had high activity on surfaces of okoumé, tineo, doussié, makoré, and both reference woods, beech and Scots pine (usually over 1 ×107 CFU/mL). The mold growth activity (MGA) of Aspergillus niger and Penicillium brevicompactum was minimal on surfaces of ipé, yellow balau, macassar ebony, doussié, bubinga, and merbau, but it was strong on surfaces of okoumé, cerejeira, ovengol, wengé, sapelli, and both reference woods. When comparing individual biological tests of (a) bacterial and mold but also (b) bacterial, mold and rot with decaying fungi C. puteana and T. versicolor, no significant relationships were found. These results confirm that the bio-durability of woods is influenced not only by their molecular structure, but also by the attacking biological pest group.
Generation of Entangled Light from a Nondegenerate Three-Level Laser Coupled to a Two-Mode Vacuum Reservoir
Authors: Abebe T. , Gashu Ch.
Published: August 2021

The quantum properties of a nondegenerate three-level cascade laser coupled to a two-mode vacuum reservoir are throughly analyzed with the use of the pertinent master equation and stochastic differential equations associated with the normal ordering. Particularly, the enhancement of squeezing and the amplification of photon entanglement of the two-mode cavity light are investigated. It is found that the two cavity modes are strongly entangled, and the degree of entanglement is directly related to the two-mode squeezing. Moreover, the squeezing and entanglement of the cavity radiation enhance with the rate of atomic injection.
Studies of Thermodynamical and Electronic Transport Properties of Na–Sn Alloy
Authors: Kumar A. , Ojha D.P.
Published: August 2021

The concept of complex formation has been incorporated in the structure of the Faber–Ziman formula for the purpose of studying the composition dependence of the electrical resistivities of Zintl alloys, which possess the anomalous nature and exhibit a large deviation from the metallic behavior around a specific composition
Зв’язок параметрів другого віріального коефіцієнта неабелевих еніонів з двопараметричними дробовими статистиками
Authors: Sobko B.Yu.
Published: August 2021

У цiй роботi показано зв’язок мiж параметрами другого вiрiального коефiцiєнта для системи неабелевих енiонiв та двопараметричними модифiкацiями дробових статистик Голдейна–Ву та Полiхронакоса. Розраховано параметри, для яких неабелевi енiони можуть описуватись даними типами статистик. Розглянуто границю, в якiй параметр неадитивностi/неповноти q прямує до одиницi.
Фундаментальні обмеження для довжини каналу провідності MOSFET з урахуванням реального вигляду бар’єрного потенціалу
Authors: Strikha M.V. , Kurchak A.I.
Published: August 2021

В статтi оцiнено мiнiмальну довжину каналу транзистора MOSFET, який є основним пристроєм сучасної електронiки. Врахування реального вигляду потенцiалу в каналi показує, що за наявностi напруги на стоку електрон тунелює крiзь область, суттєво коротшу вiд фiзичної довжини каналу L, i тому наявна в лiтературi оцiнка мiнiмальної зумовленої квантовими обмеженнями довжини каналу в кремнiєвому MOSFET Lmin ≈ 1,2 нм є суттєво заниженою. Звiдси зрозумiло, чому пiсля досягнення робочих довжин каналу в 5 нм так i не вдалося вийти на вже давно декларованi значення в 3 нм при збереженнi належного рiвня функцiональностi роботи транзистора. Зробленi в нашiй роботi оцiнки пiдтверджують: фундаментальних меж масштабування кремнiєвих MOSFET вже майже досягнуто.
Determinación de parámetros y simulación matemática del proceso de secado del cacao (Theobroma cacao)
Authors: Villamizar de Borrero Fanny , Hernández H. José Eugenio
Published: August 2021

Estudio sobre la producción de cacao en Colombia, y el incremento notable, debido principalmente al aumento en el área cultivada y a los mayores rendimientos por hectárea obtenidos.
Estudio comparativo del comportamiento de losas de concreto reforzado mediante los análisis elástico y límite
Authors: Vergara García Julio
Published: August 2021

Presenta un resumen de la tesis de grado "Estudio comparativo de losas de concreto reforzado mediante los análisis elástico y límite". Este trabajo proporciona fórmulas, tablas y gráficas prácticas para determinar los momentos flectores y el volumen de refuerzo de los tipos de losas estudiados, sometidas a diferentes tipos de carga y analizados mediante la Teoría de la Elasticidad y el Análisis Límite.
Evaluación de pérdidas en la postcosecha de la cebolla junca (Allíum Fistolosum)
Authors: Medina Díaz Roberto , Villamizar de Borrero Fanny
Published: August 2021

El presente artículo muestra los resultados obtenidos de las pérdidas postcosecha de la cebolla junca (cebolla larga o de rama), como parte de un proyecto interdisciplinario de "Precosecha, cosecha y postcosecha de frutas y hortalizas" adelantado por varias facultades de la Universidad Nacional de Colombia, el Departamento de Ingeniería Agrícola y el ICTA con la colaboración de COLCIENCIAS. La investigación se realizó en las poblaciones de Aquitania (Boyacá), zona de mayor producción en el país, la cual tiene 1.500 Há. sembradas durante todo el año, con rendimientos cercanos a las 27 toneladas por hectárea, y Usme (Cundinamarca), zona de minifundio que también siembra permanentemente esta cebolla, en aproximadamente 36.5 Há. con una producción de 146,4 toneladas por corte. Se tuvieron en cuenta estos dos sitios ya que surten diariamente el mercado de la capital del país, pero se aplican diferentes técnicas de producción y manejo entre ellos. El cultivo es económicamente representativo para los agricultores de las dos regiones, presenta distancias de transporte diferentes y con distinta topografía en su recorrido hasta llegar al sitio de comercialización en Bogotá. El objetivo principal del estudio consistió en determinar y cuantificar las pérdidas postcosecha, en la fase recolección-comercialización, en las dos zonas, analizando las pérdidas sufridas en la calidad de la cebolla debido a factores de manejo, empaque y condiciones de transporte entre las fincas y el centro de comercialización, comparando el sistema tradicional de los agricultores, con otro mejorado que se ha propuesto. Se seleccionaron 3 fincas en cada zona, en donde se hizo la cuantificación de la calidad inicial y posteriormente en el laboratorio, la de la calidad final. La caracterización física del producto se realizó inicialmente, y luego la evaluación de la calidad fue medida en índices de 0-100% de integridad y defectos. Los resultados obtenidos muestran que las características físicas de la cebolla de Aquitania arrojan resultados más altos que las de Usme. El sistema tradicional de manejo y empaque permite un 25% del deterioro de la calidad inicial, mientras que en el sistema mejorado fue de sólo un 3%. Las causas del deterioro fueron básicamente cortes, magulladuras y doblamiento. La pérdida de peso fue del 5% aproximadamente. Las condiciones ambientales y las distancias recorridas no influenciaron significativamente la pérdida de calidad.
Evaluación de filtros de arena y de malla para riego por goteo
Authors: Mendoza Roncancio Germán , Pinilla E. Fernando A. , Martínez Q. Fernando
Published: August 2021

El estudio del mecanismo de filtración y de los filtros empleados en la limpieza del agua para riego, es de gran importancia porque de su conocimiento y funcionamiento depende en gran medida la vida útil de un sistema de riego por goteo.
Actualmente existen en Colombia empresas que fabrican filtros de arena y malla para sistemas de riego por goteo, carentes de información respecto al mecanismo de filtración y a la forma como funcionan realmente los filtros que producen. Con este trabajo se quiere llenar ese vacío y proponer, además, una metodología para las evaluaciones del filtro de arena, con una rata de filtrado de 100 galones por minuto (gpm) y del filtro de malla de 100 mesh, para la misma rata de filtrado, por ser más utilizados en las instalaciones de este tipo de sistema de riego.
Los residuos sólidos industriales peligrosos en Bogotá
Authors: Collazos P. Héctor , De Castro Cielo , Riveros R. Marcelo , Ospina T. Alejandro
Published: August 2021

Los residuos sólidos provienen de diversas fuentes: doméstica, comercial, institucional, industrial, barrido de calles y limpieza de áreas públicas. Por sus características y composición, los residuos sólidos industriales, y especialmente los clasificados como peligrosos, requieren un manejo técnico y adecuado durante su almacenamiento, recolección, transporte, tratamiento y disposición final, para controlar el riesgo que presentan de causar daño a los seres vivos y al ambiente en general.
Estudio de enrocados utilizando modelos reducidos
Authors: Hernández Félix , Betancourt Cardozo Ferney , Vidales Camacho Jaime
Published: August 2021

El comportamiento de la resistencia y compresibilidad de los enrocados como un medio granular, depende en gran parte de las propiedades de sus partículas o fragmentos, no sólo en las gravas y arenas que por su origen tienen los granos más resistentes, sino también en los enrocados de una misma fuente, debido al intemperismo y a defectos como los naturales y los producidos por la acción de explosivos, manejo, extracción, transporte y colocación de la roca en el sitio; razones como éstas hacen de los enrocados naturales un material de difícil análisis con un buen grado de confiabilidad. Basados en las anteriores consideraciones, se adelantó esta investigación como proyecto de grado, partiendo de modelos adecuados para un grupo de enrocados, donde fuera posible analizar una de las principales características de los enrocados naturales, su resistencia; las evidencias experimentales indican que esta característica es función de la forma, distribución granulométrica, tamaño máximo de los granos ensayados, resistencia individual de las partículas, ángulo de fricción interparticular, y relación de vacíos inicial de la muestra de ensayo, entre otros. Los modelos de enrocados permiten estudiar la incidencia de cada uno de los factores influyentes de manera discriminada, con base en la teoría de la similitud; el material de los enrocados reducidos consistió en una mezcla de yeso, arena, agua y un aditivo, plastificante retardador usado comúnmente en concretos, la investigación estuvo dirigida al análisis y cuantificación de la influencia de la forma, distribución granulométrica y tamaño máximo de los granos del enrocado de ensayo; los demás factores como la densidad relativa inicial, ángulo de fricción interparticular y resistencia a la compresión del material o el peso unitario de sus partículas, se pretendió mantenerlos constantes. Se usaron los parámetros hiperbólicos para el análisis del comportamiento esfuerzo - deformación para suelos granulares compactados, propuestos inicialmente por Kondner y Zelasko y complementados luego por Duncan; estos parámetros que son representativos del comportamiento de los enrocados, facilitan la aplicación del análisis de similitud.
Transferencia de tecnología de sistemas alternativos de energía para la Guajira
Authors: Rodríguez Devis Julio Mario
Published: August 2021

Este artículo trata de la metodología empleada para realizar una investigación en molinos de viento para la Guajira, Colombia, en la que se hace énfasis en la transferencia de tecnología a la región y en la propuesta de solución integral a necesidades de la comunidad, dentro de una estrategia de desarrollo económico.
Políticas teleinformáticas en Colombia
Authors: Flórez Calderón Mauro
Published: August 2021

La situación de las telecomunicaciones y de la informática se describe con base en la fusión y encadenamiento de factores internos y externos, que se han visto interrelacionados a través de todo el proceso tecnológico, lo que hace imperativo enfocarlos dentro de un mismo sentido y dirección. Es así como la gran revolución de la información, desde el punto de vista técnico, edificación que tiene como grandes pilares las telecomunicaciones, la informática y la electrónica a nivel nacional, gira en torno a factores mundiales en el escenario tecnológico de fin de siglo.
Método para la determinación de los períodos de riego en el cultivo del sorgo
Authors: Mendoza Roncancio Germán , Ávila G. Henry , Figueroa V. Edgar
Published: August 2021

Uno de los aspectos importantes a considerar dentro de la producción agrícola es la evaluación del contenido de humedad y del potencial hídrico total del suelo con el fin específico de determinar el momento oportuno de regar. En Colombia no se tiene una metodología de la evaluación del momento de regar; esta evaluación generalmente se realiza a criterio subjetivo del técnico o del agricultor sin tener en cuenta, o sin utilizar elementos medidores del agua del suelo, entre las cuajes se mencionan: tensiómetros, bloques de resistencia eléctrica, el medidor de neutrones, los rayos de atenuación gamma, etc.
Cada uno de los anteriores elementos presentan problemas para su implementación, tales como su costo, difícil consecución, mantenimiento especial y constante, lo cual hace que su utilización sea muy crítica a nivel de agricultor y de técnico. Esta situación conduce a desarrollar un método de evaluación del contenido de agua en el suelo que permite en forma rápida y económica fa determinación del momento oportuno de regar, siendo el objetivo principal de esta investigación. El avance del proyecto contempla también determinar los periodos de riego en el cultivo de sorgo en la región del Tolima, establecer una metodología específica para determinar los periodos de riego a partir de la curva característica de retención de humedad y definir la relación adecuada suelo-arena para un coeficiente de agotamiento de 0,5 del cultivo mencionado.
El papel de la comunicación en los sistemas generales
Authors: Martínez Roso Ricardo
Published: August 2021

Mi incursión a través del exuberante mundo de los Sistemas me ha llevado a detectar una característica constante en todos ellos. Se trata del aspecto comunicacional presente en todas las interrelaciones que existen entre los diversos componentes de un sistema cualquiera. Esta observación me permite plantear la siguiente definición del concepto de sistema: conjunto de elementos cada uno con características propias y con relaciones de tipo Funcional y Comunicacional para lograr un conjunto de objetivos propios de este. Realmente todas las relaciones que se presentan en los sistemas tienen ese aspecto comunicacional, teniendo en cuenta la definición más restringida de este concepto, donde se exige un cambio de comportamiento en el receptor, como resultado de la influencia de un mensaje que es trasportado a través de un canal adecuado de comunicación. A continuación analizaré algunos sistemas de diferentes áreas del saber, tomando algunas relaciones entre sus elementos para corroborar mi anterior observación.
La teoría de los lazos inductivos y las fallas de los transformadores de distribución en Colombia
Authors: Román Campos Francisco
Published: August 2021

Este artículo tiene por objeto presentar la Teoría de los Lazos Inductivos - TLI - como una metodología de trabajo coherente para analizar las fallas de los transformadores de distribución en Colombia. Como variables fundamentales en la formulación de la teoría se considera la relación entre las fallas y las tormentas eléctricas; el área dejada en el montaje entre el pararrayos y el transformador y los cambios de impedancia al operar el pararrayo.
Para comprobar la teoría se analiza la relación de las fallas de los transformadores con las tormentas eléctricas en varias redes de distribución en Colombia. Igualmente se establece una primera relación entre rayos medidos y clasificados por polaridad y las fallas de unidades en el mismo periodo. Los resultados de los análisis estadísticos de más de 3.000 unidades falladas contribuyen a inferir 1a aplicabilidad de la teoría, por cuanto se encontraron más de un 70% de fallas involucrando tres fases. Se presentan finalmente las primeras simulaciones digitales mediante el EMPT, de las que se concluye la necesidad de adoptar medidas remediables adecuadas a la realidad colombiana.
Egresados de Ingeniería Eléctrica: Bogotá en cifras
Authors: Parra L. Estrella E.
Published: August 2021

Desde la creación del programa en 1961, han transitado por las aulas de Ingeniería Eléctrica miles de aspirantes, de los cuales solo una parte han culminado exitosamente sus estudios. Cuántos son? Quiénes son? Qué hacen? Dónde están? Estos y otros interrogantes son respondidos con las estadísticas que se presentan a continuación, recogidas a través del trabajo continuo y conjunto entre la Asociación y los profesores de Ingeniería Eléctrica.
Reseña histórica y descripción académica del Departamento de Ingeniería Mecánica
Authors: Abril Cárdenas Ernesto
Published: August 2021

El presente artículo contiene una breve reseña histórica del Departamento de Ingeniería Mecánica, desde su creación hace 30 años hasta la fecha, la descripción del Plan de Estudios vigente y unos cuantos datos estadísticos relacionados con profesores, estudiantes y egresados.
Fuerzas producidas en un punto dentro de la masa del suelo debidas al peso del suelo y a las presiones del agua
Authors: Hernández Rodríguez Félix
Published: August 2021

Buena parte de la labor del ingeniero de suelos radica en la evaluación de las reacciones en ciertos puntos de la masa de suelo. Esas reacciones, esfuerzo efectivo normal y esfuerzo cortante, son el producto de las fuerzas de cuerpo que afectan los puntos en cuestión. Se presentan en el artículo los dos métodos de evaluación de esas reacciones: el método del peso unitario total y de las fuerzas periféricas del agua y el método del peso unitario sumergido y la fuerza de infiltración.
Reposición del parque automotor carretero
Authors: Regueros Chosnek Fabio
Published: August 2021

Desde hace ya más de veinte años se viene hablando en Colombia de la necesidad de adelantar un programa de reposición de los vehículos utilizados en el servicio público de transporte de pasajeros y carga. Se señala la obsolescencia del parque representada por su elevada edad promedio. Sin embargo, hasta la fecha, y con la excepción de los programas adelantados por la CFT en la financiación de taxis, es muy poco lo que institucionalmente se ha hecho para modernizar la flota de servicio público en el país.
El área socio-humanística y la formación integral del ingeniero
Authors: Sánchez Bolívar Guillermo
Published: August 2021

Con la inclusión de una área socio-humanística en los planes de estudios universitarios se ha buscado disminuir el énfasis profesionalizante de las carreras, al complementar el núcleo profesional con algún grado de formación e información en otros aspectos. Desafortunadamente, en muchos casos dicha área se reduce a un conjunto de cursos secundarios, desarticulado del resto de los planes de estudios, que no constituye un aporte significativo en la educación de los estudiantes.
Por otra parte, si se acepta que la universidad debe propiciar la formación integral de sus estudiantes, es necesario desarrollar estrategias adecuadas para tal fin. La existencia de una área socio-humanística debidamente estructurada dentro de los planes de estudios no garantiza la formación integral, pero si constituye un valioso punto de apoyo para promoverla. En este artículo se analizan los planteamientos anteriores y se proponen algunas alternativas para estructurar el área socio-humanística en los planes de estudios de las carreras ofrecidas por la Facultad de Ingeniería.
Design and Analysis of a Bulge Test Device
Authors: Martínez Palmeth Luis Humberto , Gonzalez Carmona María Angelica , Miranda Castro José
Published: August 2021

The aim of this work is to present the methodological process to design a device capable of performing Bulge tests. This kind of device allows obtaining more information about the plastic behavior of a material than the one provided by a traditional tensile test. The engineering specifications of the device were evaluated through the QFD methodology. Then, a basic design of the device was performed based on available analytical models such as thick-walled pressure vessel theory, annular plate theory, and a basic plasticity model for the biaxial stress state. Later, a detailed design of the device was proposed, which was evaluated by means of a 3D model of finite elements and a linearstatic analysis for the main components. Finally, a 2D axisymmetric model and a dynamic non-linear analysis were performed to validate the proposed design. The main novelty of the work consists of articulating the methodology of the mechanical design process and the conception, design, and validation of a Bulge device while solving the deficiencies found in the literature regarding the design and validation processes of this type of devices.
Cost Forecasting of Public Construction Projects Using Multilayer Perceptron Artificial Neural Networks: A Case Study
Authors: Pessoa Alcineide , Sousa Gean , Maués Luiz , Alvarenga Felipe , Santos Débora
Published: August 2021

The execution of public sector construction projects often requires the use of financial resources not foreseen during the tendering phase, which causes management problems. This study aims to present a computational model based on artificial intelligence, specifically on artificial neural networks, capable of forecasting the execution cost of construction projects for Brazilian educational public buildings. The database used in the training and testing of the neural model was obtained from the online system of the Ministry of Education. The neural network used was a multilayer perceptron as a backpropagation algorithm optimized through the gradient descent method. To evaluate the obtained results, the mean absolute percentage errors and the Pearson correlation coefficients were calculated. Some hypothesis tests were also carried out in order to verify the existence of significant differences between real values and those obtained by the neural network. The average percentage errors between predicted and actual values varied between 5% and 9%, and the correlation values reached 0,99. The results demonstrated that it is possible to use artificial intelligence as an auxiliary mechanism to plan construction projects, especially in the public sector.