Search results for "spring"
showing 10 items of 600 documents
Aprendiendo Vibraciones Mec´anicas con Wolfram Mathematica
2015
[EN] Mechanical vibrations as subject can be found within many Engineering and Science Degrees. To achieve that the students understand the mathematics and its physical interpretation is the objective we should get as docents. In this paper we describe how to create a simple graphical model of a single degree of freedom vibrating system allowing us to visualize concepts like above concepts damping, resonance or forced vibrations. For that, we use the popular symbolic software Wolfram Mathematica with which, without an excessive programming complexity, we can obtain a very satisfactory visual model capable to move itself, controlled by parameters. In addition, the model incorporates the curv…
Chernobyl exposure as stressor during pregnancy and behaviour in adolescent offspring.
2007
Objective: Research in animals has shown that exposure to stressors during pregnancy is associated with offspring behavioural disorders. We aimed to study the effect of in utero exposure to the Chernobyl disaster in 1986, and maternal anxiety presumably associated with that exposure, on behaviour disorder observed at age 14. Method: Exposed (n = 232) and non-exposed Finnish twins (n = 572) were compared. A semi-structured interview was used to assess lifetime symptoms of depression, generalized anxiety disorder, attention deficit hyperactivity disorder, conduct disorder and oppositional defiant disorder symptoms. Results: Adolescents who were exposed from the second trimester in pregnancy o…
Exact Mechanical Hierarchy of Non-Linear Fractional-Order Hereditariness
2020
Non-local time evolution of material stress/strain is often referred to as material hereditariness. In this paper, the widely used non-linear approach to single integral time non-local mechanics named quasi-linear approach is proposed in the context of fractional differential calculus. The non-linear model of the springpot is defined in terms of a single integral with separable kernel endowed with a non-linear transform of the state variable that allows for the use of Boltzmann superposition. The model represents a self-similar hierarchy that allows for a time-invariance as the result of the application of the conservation laws at any resolution scale. It is shown that the non-linear spring…
Decreased sexual signalling reveals reduced viability in small populations of the drumming wolf spider Hygrolycosa rubrofasciata.
2004
One of the important goals in conservation biology is to determine reliable indicators of population viability. Sexual traits have been suggested to indicate population extinction risk, because they may be related to viability through condition dependence. Moreover, condition-dependent sexual traits may be more sensitive indicators of population viability than early life-history traits, because deleterious fitness effects of inbreeding tend to be expressed mainly at the end of the species' life history. However, empirical evidence of the significance of sexual behaviour for population viability is missing. In this study, we examined two male sexual traits and survival in 39 different-sized …
Optimal damping coefficient for a class of continuous contact models
2020
AbstractIn this study, we develop an analytical formula to approximate the damping coefficient as a function of the coefficient of restitution for a class of continuous contact models. The contact force is generated by a logical point-to-point force element consisting of a linear damper connected in parallel to a spring with Hertz force–penetration characteristic, while the exponent of deformation of the Hertz spring can vary between one and two. In this nonlinear model, it is assumed that the bodies start to separate when the contact force becomes zero. After separation, either the restitution continues or a permanent penetration is achieved. Therefore, this model is capable of addressing …
A Look at Valencia’s Elections of the 28th of April and the 26th of May 2019
2020
This paper analyses the main features of the Valencian media coverage of the elections held in Spain in the Spring of 2019 (General, Regional, Municipal, and European elections). We shine a spotlight on the key themes covered by the main newspapers, radio and TV stations, and on the campaign strategies parties used to define ideological blocs on the left and right.
PREDICTION OF HARVEST TIME IN PEACH [PRUNUS PERSICA (L.) BATSCH] FRUIT USING THE DA-METER
2015
The aim of this work was to define the most appropriate time of harvesting early ripening peach fruit using destructive and non-destructive quality indexes such as the index of absorbance (IAD), measured with the DA-Meter, a portable equipment able to measure the degradation of chlorophyll in the pericarp. In this context our research was carried out in 2009 and 2010 on several peach cultivars. Total soluble solid content increased while flesh firmness and total acidity decreased with IAD values, but no significant correlation was found between destructive and non-destructive parameters.
Maternal body mass index, gestational weight gain, and the risk of overweight and obesity across childhood: An individual participant data meta-analy…
2019
Background Maternal obesity and excessive gestational weight gain may have persistent effects on offspring fat development. However, it remains unclear whether these effects differ by severity of obesity, and whether these effects are restricted to the extremes of maternal body mass index (BMI) and gestational weight gain. We aimed to assess the separate and combined associations of maternal BMI and gestational weight gain with the risk of overweight/obesity throughout childhood, and their population impact. Methods and findings We conducted an individual participant data meta-analysis of data from 162,129 mothers and their children from 37 pregnancy and birth cohort studies from Europe, No…
Personāla laika uzskaites sistēmas izveide
2019
Kvalifikācijas darba ietvaros tika izveidota personāla laika uzskaites sistēma, ar kuras palīdzību var pārvaldīt informāciju par darbiniekiem, tabelēm un to ierakstiem, grafikiem un notikumiem tajos. Šajā sistēmā piekļuve ir paredzēta darbiniekiem, kuriem ir izveidots konts. Tiešajiem vadītājiem ir iespējams izveidot, labot, apstiprināt, noraidīt un dzēst viņu padoto darbinieku grafikus, tabeles un notikumus. Sistēma sastāv no 2 daļām – lietotāju puses, ar kuru darbojas lietotājs, un servera puses, kas veic datu apstrādi. Sistēmai ir 3 moduļi – darbinieku, grafiku un tabeļu. Sistēmas izstrādē tiek izmantota Java programmēšanas valoda ar Spring Boot ietvaru, H2 Database Engine, vuex un vue.j…
Bibliotēkas pārvaldības sistēma
2021
Bibliotēkas pārvaldības sistēma paredzēta bibliotēkā esošo grāmatu un to izsniegumu uzskaitei. Tās galvenais uzdevums ir atvieglot bibliotekāriem izsekošanu tam, kādas grāmatas ir pieejamas bibliotēkā, kā arī grāmatu izsniegumu reģistrēšanu, izmantojot tīmekļa lietotni. Šī sistēma ir paredzēta četrām lietotāju grupām – viesim, reģistrētam lietotājam, bibliotekāram un administratoram. Tā dod iespēju meklēt kādas grāmatas ir bibliotēkā pēc to nosaukuma, to autorus, kā arī meklēt izsniegumu pēc lietotāja vārda vai uzvārda. Bibliotekāri var veidot grāmatu izsniegumus tikai tiem lietotājiem, kuri ir reģistrējušies sistēmā