scholarly journals Análisis de Confiabilidad en Subestaciones Eléctricas Tipo Maniobra Implementando el Transformador de Tensión con Núcleo de Potencia

Ingeniería ◽  
2017 ◽  
Vol 22 (1) ◽  
pp. 140
Author(s):  
Diego Ernesto Viteri ◽  
César Andrés Garzón Bustos ◽  
Eider Alexander Narvaez Cubillos
Keyword(s):  
Current System ◽  
Lower Probability ◽  
Voltage Transformer ◽  
Collaborative Project ◽  
Energy Company ◽  
Before And After ◽  
Transformer Power ◽  
Electricity Power ◽  
Two Stages ◽  
Auxiliary Services

Context: It is intended to conduct a technical study of a voltage transformer power core, used for the supply of the auxiliary services of a maneuver type substation, hoping to mitigate the possibility of losing the continuous electricity power supply and likewise reducing the dependency with the external supplier. This is a result of a collaborative project between the Bogota Energy Company and the Universidad Distrital Francisco Jose de Caldas.Method: The study consists of two stages, the first one is an analysis of reliability of the substation auxiliary systems, carried out in three scenarios: before and after use of the transformer and using a unique generator for auxiliary services. The second one is simulation using the ATP software to verify the behavior of the equipment in transient state.Results: The reliability of auxiliary services increased after the equipment has been installed, as the failure rate went from 0.31 [failure/year] with the current system, to become 0.0025 [failure/year].Conclusions: The implementation of transformer is suitable for substations that do not have a reliable power system auxiliary services as it makes the substation auto dependent. Implement this system in Colombia would get a big increase in the reliability of the auxiliary services in maneuver type substations and therefore a lower probability of loss.

scholarly journals Eco-Friendly Fired Brick Produced from Industrial Ash and Natural Clay: A Study of Waste Reuse

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 877 ◽  
Author(s):  
Neslihan Doğan-Sağlamtimur ◽  
Ahmet Bilgil ◽  
Magdalena Szechyńska-Hebda ◽  
Sławomir Parzych ◽  
Marek Hebda
Keyword(s):  
Compressive Strength ◽  
Bottom Ash ◽  
Unit Weight ◽  
Waste Reuse ◽  
Industrial Solid Waste ◽  
Second Stage ◽  
Before And After ◽  
Fired Bricks ◽  
Two Stages ◽  
And Storage

Bottom ash (BA) is an industrial solid waste formed by the burning of coal. The environmental problems and storage costs caused by this waste increase with every passing day. In this study, the use of BA as an additive (clay substitute) in fired brick production was investigated. The study consisted of two stages. In the first stage, cylinder blocks were produced from clay used in brick production. The second stage was the examination of the experimental substitution of clay with 10, 20, 30 and 40% BA. Samples were fired at 900, 1000, 1100 and 1150 °C to produce fired brick samples. The unit weight, compressive strength (before and after freeze–thawing) and water absorption were analyzed for the samples. The unit weight values decreased in the samples containing BA. The mechanical properties met the conditions prescribed in the relevant standards; i.e., all of the samples fired at 1100 and 1150 °C had a sufficient compressive strength over 20 MPa. The high potential of fired bricks for the construction industry was proved. BA can be used as a clay substitute, while the developed protocol can be used to effectively produce fired bricks.

scholarly journals Design of experiments for verification of computational life prediction methods

2019 ◽  
Vol 18 (3) ◽  
pp. 143-154
Author(s):  
O. V. Samsonova ◽  
K. V. Fetisov ◽  
I. V. Karpman ◽  
I. V. Burtseva
Keyword(s):  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Turbine Engines ◽  
Prediction Methods ◽  
Gas Turbine Engines ◽  
Loading Conditions ◽  
Load History ◽  
Strain Behavior ◽  
Before And After ◽  
Two Stages

The failure of heavily loaded rotating parts of aviation gas turbine engines may bring about dangerous consequences. The life of such parts is limited with the use of computational and experimental methods. Computational life prediction methods that are used without carrying out life-cycle tests of engine parts or assemblies should be substantiated experimentally. The best option for verifying the computational methods is to use the results of cyclic tests of model disks. These tests make it possible to reproduce loading conditions and surface conditions that correspond to those of real disks, and the data on the load history and material properties make it possible to simulate stress-strain behavior of disks under test conditions by calculation. This paper shows the process of planning such tests. It is assumed that the tests will be carried out in two stages - before and after the initiation of a low-cycle fatigue crack. A number of criteria are formulated that the geometry of model disks and their loading conditions are to satisfy. Based on these criteria, model disks were designed and the conditions for their testing were selected.

scholarly journals Awareness of COVID-19 Before and After Quarantine Based on Crowdsourced Data From Rabigh City, Saudi Arabia: A Cross-Sectional and Comparative Study

2021 ◽  
Vol 9 ◽  
Author(s):  
Mai Aldhahri ◽  
Rana Alghamdi
Keyword(s):  
Saudi Arabia ◽  
Online Survey ◽  
Control Measures ◽  
Infection Prevention And Control ◽  
Cross Sectional ◽  
Second Stage ◽  
Before And After ◽  
Prevention And Control Measures ◽  
Two Stages ◽  
And Control

Background: Infection prevention and control measures are critical for the prevention of the spread of COVID-19.Aim: In this study, we aimed to measure and evaluate the level of awareness and knowledge of the prevention, symptoms, and transmission control of COVID-19 before and after quarantine among the residents of Rabigh city and adjacent villages in Saudi Arabia.Methods: A cross-sectional online survey was conducted in two stages: the first stage took place before quarantine and the second stage took place after quarantine. The survey was filled out electronically.Results: A total of 448 participants responded and filled out the questionnaires. Females (73.70%) formed the largest number of participants for both stages. The majority of the participants were <30 years old (50.90%) and had a high education level in various sectors and levels (97.1%). It was noticeable that during the first stage, the participants' awareness of COVID-19 symptoms was not very high: 13.62% did not know about the symptoms. However, by the second stage, awareness about symptoms had increased (9.6%).Conclusion: The residents of Rabigh city and the surrounding villages had good levels of knowledge about COVID-19.

scholarly journals Are We Aware of What Is Going on in a Student’s Mind? Understanding Wrong Answers about Plant Tropisms and Connection between Student’s Conceptions and Metacognition in Teacher and Learner Minds

2018 ◽  
Vol 8 (4) ◽  
pp. 164
Author(s):  
Ewa Sobieszczuk-Nowicka ◽  
Eliza Rybska ◽  
Joanna Jarmużek ◽  
Małgorzata Adamiec ◽  
Zofia Chyleńska
Keyword(s):  
Teacher Training ◽  
University Students ◽  
Alternative Conceptions ◽  
Sample Survey ◽  
Academic Training ◽  
Biology Students ◽  
Before And After ◽  
Curse Of Knowledge ◽  
Two Stages ◽  
Academic Teacher

Problems with understanding concepts and mechanisms connected to plant movements have been diagnosed among biology students. Alternative conceptions in understanding these phenomena are marginally studied. The diagnosis was based on a sample survey of university students and their lecturers, which was quantitatively and qualitatively exploratory in nature (via a questionnaire). The research was performed in two stages, before and after the lectures and laboratory on plant movements. We diagnosed eight alternative conceptions before the academic training started. After the classes, most were not been verified, and in addition, 12 new conceptions were diagnosed. Additionally, we report that teachers are not aware of students’ possible misunderstandings. They do not perceive students’ troubles with switching between levels of representations, nor their alternative conceptions. A case of “curse of knowledge” was observed and academic teacher training is recommended. Additionally, the need for metacognition as a crucial element in laboratory activities seems supported by our presented results. Such metacognition refers to students as well as teachers, which leads to the conclusion that teachers should be aware of students’ way of thinking and the development of knowledge in one’s own mind.

scholarly journals Nanocrystalline Ga–Zn Oxynitride Materials: Minimized Defect Density for Improved Photocatalytic Activity?

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Sasa Lukic ◽  
Gerdina Wilhelmina Busser ◽  
Siyuan Zhang ◽  
Jasper Menze ◽  
Martin Muhler ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Defect Density ◽  
Chemical Vapor ◽  
Band Gap Energy ◽  
Lower Probability ◽  
Nitridation Time ◽  
Carrier Recombination ◽  
Synthesis Strategy ◽  
Before And After ◽  
Time Band

Abstract We present an alternative synthesis strategy for developing nanocrystalline (Ga1−xZnx)(N1−xOx) semiconductors known to be very efficient photoabsorbers. In a first step we produce mixtures of highly crystalline β-Ga2O3 and wurtzite-type ZnO nanoparticles by chemical vapor synthesis. (Ga1−xZnx)(N1−xOx) nanoparticles of wurtzite structure are then formed by reaction of these precursor materials with ammonia. Microstructure as well as composition (zinc loss) changes with nitridation time: band gap energy, crystallite size and crystallinity increase, while defect density decreases with increasing nitridation time. Crystallite growth results in a corresponding decrease in specific surface area. In the UV regime photocatalytic activity for overall water splitting can be monitored for samples both before and after nitridation. We find a significantly lower photocatalytic activity in the nitrided samples, even though the crystallinity is significantly higher and the defect density is significantly lower after nitridation. Both properties should have led to a lower probability for charge carrier recombination, and, consequently, to a higher photocatalytic activity.

Attitude of the Canine in Secondary Bone-Grafted and Nongrafted Patients with Cleft Lip and Palate

2005 ◽  
Vol 42 (6) ◽  
pp. 679-686 ◽  
Author(s):  
Enkhtuvshin Gereltzul ◽  
Yoshiyuki Baba ◽  
Kimie Ohyama
Keyword(s):  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Panoramic Radiography ◽  
Control Groups ◽  
Significant Difference ◽  
Before And After ◽  
Group 2 ◽  
Two Stages ◽  
And Control ◽  
Group 1

Objective To investigate the eruption pattern of the cleft-side canine regarding its pre-eruption position relative to the cleft in bone-grafted (BG) and nongrafted (NonBG) patients with cleft lip and palate. Methods Fifty-three patients with cleft lip and palate (21 BG, 32 NonBG) were examined by panoramic radiography and posteroanterior cephalography taken before and after canine eruption. Subjects were categorized into BG, NonBG, and control groups. Canines at the pre-eruption stage were categorized as close to (group 1) or distant from (group 2) the cleft area. The canine angle and its change between the two stages were evaluated. Results No significant differences were noted between the initial canine angle of the BG and NonBG groups. Although canines in the BG group erupted without a significant change in angle, the canine angle increased significantly (p < .0001) in the NonBG and control groups. In group 1, a greater change in canine angle was noted in the NonBG (p < .05) and control (p < .01) groups than in the BG group. In group 2, no significant difference was noted among the three groups. Conclusions In BG patients, a canine located near the cleft appears to erupt at the same angle as it had before grafting. However, in NonBG patients, it erupts more vertically, guided by cortical bone. For canines distant from the cleft area, there is no significant difference in the change in angulation between NonBG and BG patients.

Research on Bearing Capacity of Column Underpinning Joint of Frame Structure Moving

2011 ◽  
Vol 243-249 ◽  
pp. 426-430 ◽  
Author(s):  
Ai Hua Du ◽  
He Qi Tang
Keyword(s):  
Bearing Capacity ◽  
Mechanical Model ◽  
Frame Structure ◽  
Deep Beam ◽  
Interface Shear ◽  
Joint Stress ◽  
Failure Type ◽  
Before And After ◽  
Interface Slip ◽  
Two Stages

An experiment of sixteen frame column underpinning joints of frame structure moving was introduced, the experiment sample failure phenomena and failure type was obtained. The type was like “deep beam” failure type-“tension bar arch”, and the last failure place occurred on the interface of column and beam. Then, the underpinning joint stress mechanism and failure mode was determined based on the experiment’s conclusion. In addition, the failure course of joint was divided two stages which were before and after interface punching slip by theoretical analysis, for the stage before interface punching slip a space “tension-bar-arch” mechanical model was presented for the underpinning joint, then theoretical bearing capacity equation for this underpinning joint were obtained. At the same time, for the stage of interface after punching slip, the theory of interface shear was put into the analysis of joint, then interface bearing capacity equation was obtained for this stage. At last the height equation was obtained by the analysis of the stage of after interface slip.

scholarly journals Employment and earnings trajectories before and after sickness absence due to major depressive disorder: a nationwide case–control study

2020 ◽  
pp. oemed-2020-106660
Author(s):  
Christian Hakulinen ◽  
Petri Böckerman ◽  
Laura Pulkki-Råback ◽  
Marianna Virtanen ◽  
Marko Elovainio
Keyword(s):  
Major Depressive Disorder ◽  
Depressive Disorder ◽  
Sickness Absence ◽  
Lower Probability ◽  
Control Group ◽  
Major Depressive ◽  
Earnings Losses ◽  
Before And After ◽  
History Of ◽  
And Gender

ObjectivesTo examine employment and earnings trajectories before and after the first sickness absence period due to major depressive disorder (MDD).MethodsAll individuals (n=158 813) in Finland who had a first sickness absence period (lasting longer than 9 days) due to MDD between 2005 and 2015 were matched with one randomly selected individual of the same age and gender with no history of MDD. Employment status and earnings were measured using register-based data annually from 2005 to 2015. Generalised estimating equations were used to examine the trajectories of employment and earnings before and after MDD diagnosis in men and women separately.ResultsSickness absence due to MDD was associated with increased probability of non-employment during and after the year of the first sickness absence period. In men, but not in women, the probability of being employed was lower 5 years before the sickness absence period due to MDD. When compared with the individuals in the control group, men had around 34% and women 15% lower earnings 1 year, and 40% and 23%, respectively, 5 years, after the first sickness absence period due to MDD. More severe MDD and longer duration of sickness absence period were associated with lower probability of being employed.ConclusionsSickness absence due to MDD was associated with considerable reduction in employment and earnings losses. For men and individuals with more severe MDD, this reduction was before the first sickness period. This supports a reciprocal association between employment and earnings with MDD.

Photography and the Perils of Automaticity: P. H. Emerson, Copyright, and the Agency of the Artist

2020 ◽  
Author(s):  
JiHae Koo
Keyword(s):  
Copyright Law ◽  
Aesthetic Theory ◽  
Medium Specificity ◽  
Cultural Imaginary ◽  
Before And After ◽  
Artistic Medium ◽  
The Aesthetic ◽  
Two Stages ◽  
The Relationship

Abstract The photographer Peter Henry Emerson (1856–1936) is known today for the splash he made on the Victorian photographic scene in the 1880s with his bold refusal to follow his fellow art photographers (collectively known as the Pictorialists) in latching the new medium on to the aesthetic conventions of painting. His conventional position within art history is thus as a precursor to the Modernist conception of photography’s medium-specificity. Yet even if Emerson’s work was ahead of its time in its proto-Modernist refusal of painterly conventions, it also has qualities that place it more squarely within late-Victorian discourses. In particular, I argue, Emerson’s ongoing efforts to secure his photographs via copyright law need to be understood as reflective of a distinctly nineteenth-century cultural imaginary. This essay addresses the relationship between Emerson’s aesthetic theory and copyright law by dividing Emerson’s career into two stages, before and after 1891, this being the year in which Emerson abruptly disavowed photography as an artistic medium in his short pamphlet ‘The Death of Naturalistic Photography’. Examining two photography books – Pictures of East Anglian Life (1888) and On English Lagoons (1893) – alongside late-Victorian debates about photographic copyright, I show that Emerson’s earlier belief in photographic copyright’s ability to retain the integrity of an artist’s vision breaks down after 1891. He loses faith in the ‘copyrightability’ of photography in 1891 when he recognizes the mechanical nature – or automaticity – of the camera. That is, Emerson realizes that the photograph is never purely the product of the artist. In sum, this case study shows that by the 1890s, photographic copyright was becoming detached from the notion of creativity and thus could no longer be the guarantee of a photographer’s claim to artistic individuality.

Europeanisation of Polish Law Following Poland’s Accession to the European Union

2017 ◽  
Vol 71 (0) ◽  
pp. 61-71
Author(s):  
Robert Grzeszczak
Keyword(s):  
European Union ◽  
Legal System ◽  
The European Union ◽  
National Legal System ◽  
Before And After ◽  
The Government ◽  
Polish Law ◽  
Two Stages ◽  
The Relationship ◽  
The Eu

The article concerns primarily the effects of the membership of the European Union on national (Polish) law and, to a limited extent, on the political system of a state. The conclusions presented in the article are of universal value. Although the article deals with Polish affairs, the principles, tendencies and consequences identified are typical of the relationship state – the EU, both before and after accession, regardless of the state concerned. It should be, however, noted that the path to membership and the membership itself are different in each case. The practice of the Polish membership of the European Union, its systemic dimension and the changes in the national legal system (Europeanisation) do not differ significantly than in the case of other Member States. Europeanisation of Polish law, politics, economy, culture and society has been in progress since the 1990s. One can differentiate between two stages of Europeanisation: before and after Poland’s EU accession, each characterised by different conditions. Over time, this process, on the whole, has been undergoing numerous changes but it has never weakened in importance. Poland faces issues such as poor legitimation of integration processes, supremacy of the government over the parliament, passivity of parliamentary committees in controlling the government and EU institutions in the decision making process, as well as dilution of responsibility for decisions taken within the EU. The process of Europeanisation relies mostly on direct application of the standards of EU law in the national legal system, implementation of directives into national law and harmonisation or standardisation of national legal solutions so that they comply with the EU framework. It is also reception of a common, European (Union) axiology.

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