1,157 research outputs found
First order transitions by conduction calorimetry: Application to deuterated potassium dihydrogen phosphate ferroelastic crystal under uniaxial pressure
The specific heat c and the heat power W exchanged by a Deuterated Potassium Dihydrogen Phosphate ferroelectric-ferroelastic crystal have been measured simultaneously for both decreasing and increasing temperature at a low constant rate (0.06 K/h) between 175 and 240 K. The measurements were carried out under controlled uniaxial stresses of 0.3 and 4.5±0.1 bar applied to face (110). At Tt=207.9 K, a first order transition is produced with anomalous specific heat behavior in the interval where the transition heat appears. This anomalous behavior is explained in terms of the temperature variation of the heat power during the transition. During cooling, the transition occurs with coexistence of phases, while during heating it seems that metastable states are reached. Excluding data affected by the transition heat, the specific heat behavior agrees with the predictions of a 2-4-6 Landau potential in the range of 4–15 K below Tt while logarithmic behavior is obtained in the range from Tt to 1 K below Tt. Data obtained under 0.3 and 4.5 bar uniaxial stresses exhibit the same behavior.Dirección General de Investigación Científica y Técnica. Gobierno de España-PB91-60
Memory effect in triglycine sulfate induced by a transverse electric field: specific heat measurement
The influence of a transverse electric field in the specific heat of
triglycine sulphate (TGS) has been studied. The specific heat of TGS has been
measured heating the sample from ferroelectric to paraelectric phase after
prolonged transverse electric field (i.e. perpendicular to the ferroelectric
axis). It is shown that the specific heat of TGS can remember the temperature
at which the transverse field was previously applied.Comment: ReVTeX4 Twocolumn 4 pages, 4 figure
Influence of the electric field on the latent heat of the ferroelectric phase transition in KDP
The specific heat, heat flux (DTA trace) and dielectric constant of KDP
ferroelectric crystal have been measured simultaneously for various electric
fields with a conduction calorimeter. The specific heat presents a strong
anomaly but these simultaneous measurements allow us to evaluate the latent
heat accurately. Latent heat decreases with field and the value of critical
electric field --that where latent heat disappears-- is estimated to be
(0.44\pm0.03) kV/cm. Incidentally, we have measured simultaneously the
dielectric permittivity which suggests that latent heat is developed as domains
are growing.Comment: 7 pages, 6 figures, ReVTeX, twocolumn format, to appear in J. Phys.
Cond. Matte
The importance of early parenting for later child outcomes: A study with Spanish families with children with disabilities
Children with different disability conditions have varied developmental trajectories, which perhaps influences parent-child interaction. For these and all infants, an optimal home environment that includes good parenting and positive parent-child interactions predicts better developmental outcomes (Spiker et al., 2005). Interventions using a family-centered, parenting-focused approach result in better parenting behavior that contributes to improved early child development (Avellar & Suplee, 2013; Roggman & Cardia, 2016). Information on parent-child interaction patterns is needed to guide intervention in natural contexts of families (Fuligni & Brooks-Gunn, 2013). Parent-child interaction data were collected from 44 mothers and 35 fathers interacting with their children (23 to 47 months) who had a disability and were in one of eight Spanish Early Interventions Centers. Mothers and fathers, separately, auto-recorded 10-minute play sessions at home. Parental interactions were assessed using PICCOLO (Roggman et al., 2013), a standardized measure of parenting. Two independent observers coded the interactions; strong intra-class correlation coefficients were found (.82 to .97 for mothers, .77 to .89 for fathers). The BSID-III scales (Bayley, 2015) assessed children’s development. Mothers scored slightly higher than did fathers. Scores varied by PICCOLO domains but were consistent with other PICCOLO studies of typical developing children (Roggman et al., 2013). Mother and father’s scores correlated indicating that the higher the scores of mothers in any dimension correlated with those of the parents combined. Positive significant Pearson correlations were found between parenting and child’s development with different patterns of father and mother domains predicting better language and cognitive outcomes. Although barriers to optimal parenting need further investigation, PICCOLO can be a useful tool to support optimal parenting.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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Modelling and Analysis of Vibrations in a UAV Helicopter with a Vision System
The analysis of the nature and damping of unwanted vibrations on Unmanned Aerial Vehicle (UAV) helicopters are important tasks when images from on‐board vision systems are to be obtained. In this article, the authors model a UAV system, generate a range of vibrations originating in the main rotor and design a control methodology in order to damp these vibrations. The UAV is modelled using VehicleSim, the vibrations that appear on the fuselage are analysed to study their effects on the on‐board vision system by using Simmechanics software. Following this, the authors present a control method based on an Adaptive Neuro‐Fuzzy Inference System (ANFIS) to achieve satisfactory damping results over the vision system on board
Avalanche criticality in the martensitic transition of Cu67.64Zn16.71Al15.65 shape-memory alloy: a calorimetric and acoustic emission study
The first-order diffusionless structural transition in Cu67.64Zn16.71Al15.65 is characterized by jerky propagation of phase fronts related to the appearance of avalanches. In this paper, we describe a full analysis of this avalanche behavior using calorimetric heat-flux measurements and acoustic emission measurements. Two different propagation modes, namely, smooth front propagation and jerky avalanches, were observed in extremely slow measurements with heating and cooling rates as low as a few 10−3 K/h. Avalanches show criticality where each avalanche leads to a spike in the heat flux. Their statistical analysis leads to a power law [P(E)∼E−ε, where P(E)dE is the probability to observe an avalanche with energy E in an interval between E and E+dE] with an energy exponent of ε=2.15±0.15 in excellent agreement with the results of acoustic emission measurements. Avalanches appear to be more common for heating rates faster than 5×10−3 K/h whereas smooth front propagation occurs in all calorimetric measurements and (almost) exclusively for slower heating rates. Repeated cooling runs were taken after a waiting time of 1 month (and an intermediate heating run). Correlations between the avalanche sequences of the two cooling runs were found for the strongest avalanche peaks but not for the full sequence of avalanches. The memory effect is hence limited to strong avalanches
Marginal product elasticity of productive factors. a translog function estimate for spanish provinces
La relación entre los principales factores productivos de una economía
es, junto con sus niveles de dotación, uno de los elementos determinantes del
crecimiento económico. Actualmente existen todavía escasos trabajos empíricos
que hayan estudiado la forma en que estos factores se relacionan entre sí y cómo
esa relación afecta al crecimiento de la productividad en los distintos territorios.
En este trabajo se estima una función de producción obtenida mediante el producto
de la productividad total de los factores y del input total de factores, que viene
dado a su vez por una función translogarítmica para cuatro factores productivos,
lo que permite dotar de mayor flexibilidad a la función estimada. Los parámetros
de la función estimada permiten una interpretación en términos de la posible
complementariedad o sustituibilidad entre factores, así como la existencia o no de
rendimientos crecientes o decrecientes de los factores considerados. Asimismo,
se calcula la elasticidad del producto marginal de cada factor respecto al resto de
los factores y respecto al mismo factor, con el fin de analizar las relaciones entre
estos factores y el modo en que afectan al crecimiento de la productividad en las
provincias españolas, en el periodo comprendido entre 1985-2008.The relationship between the main production factors in an economy
is, along with their levels, one of the determinants of economic growth. Currently
there are still few empirical studies which have examined how these factors relate to each other and how that relationship affects the productivity growth in different
territories. This paper considers a production function obtained by the product
of the total factor productivity and the total factor input. The total factor input is
given by a translog function of four factors of production, allowing greater flexibility
to the estimated function. The parameters of the estimated function allows an
interpretation in terms of the possible complementarity or substitutability between
factors as well as the existence of increasing or decreasing returns to the factors
considered. Also, the elasticity of the marginal product of each factor relative to
other factors, and compared to the same factor, is calculated in order to analyze the
relationships between these factors. How these relationships affect productivity
growth in the Spanish provinces is estimated at the period from 1985 to 2008
Exploration Medical System Trade Study Tools Overview
ExMC is creating an ecosystem of tools to enable well-informed medical system trade studies. The suite of tools address important system implementation aspects of the space medical capabilities trade space and are being built using knowledge from the medical community regarding the unique aspects of space flight. Two integrating models, a systems engineering model and a medical risk analysis model, tie the tools together to produce an integrated assessment of the medical system and its ability to achieve medical system target requirements. This presentation will provide an overview of the various tools that are a part of the tool ecosystem. Initially, the presentation's focus will address the tools that supply the foundational information to the ecosystem. Specifically, the talk will describe how information that describes how medicine will be practiced is captured and categorized for efficient utilization in the tool suite. For example, the talk will include capturing what conditions will be planned for in-mission treatment, planned medical activities (e.g., periodic physical exam), required medical capabilities (e.g., provide imaging), and options to implement the capabilities (e.g., an ultrasound device). Database storage and configuration management will also be discussed. The presentation will include an overview of how these information tools will be tied to parameters in a Systems Modeling Language (SysML) model, allowing traceability to system behavioral, structural, and requirements content. The discussion will also describe an HRP-led enhanced risk assessment model developed to provide quantitative insight into each capability's contribution to mission success. Key outputs from these various tools, to be shared with the space medical and exploration mission development communities, will be assessments of medical system implementation option satisfaction of requirements and per-capability contributions toward achieving requirements
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