Energy and Economic Growth: The Stylized Facts Csereklyei, Zsuzsanna; Rubio-Varas, M. d. Mar; Stern, David I.
The Energy journal (Cambridge, Mass.),
04/2016, Letnik:
37, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We summarize what we know about energy and economic growth in a set of stylized facts. We combine analysis of a panel data set of 99 countries from 1971 to 2010 with analysis of some longer run ...historical data. Our key result is that over the last 40 years there has been a stable cross-sectional relationship between per capita energy use and income per capita with an elasticity of energy use with respect to income of less than unity. This implies that energy intensity has tended to decrease in countries that have become richer but not in others. We also find that over the last two centuries there has been convergence in energy intensity towards the current distribution, per capita energy use has tended to rise and energy quality to increase, and, though evidence is limited, the cost share of energy has declined.
Celotno besedilo
Dostopno za:
BFBNIB, CEKLJ, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This work proposes the experimental study of an auxetic polymeric structure manufactured by 3D printing (SLA). The structure is composed by a re-entrant unit cell based on cylindrical elements not ...previously studied. The effect of the number and size/scale of the unit cells used in the specimens, subjected to both static and dynamic loads, has been analysed. The results show how the studied variables affect the behaviour of the structure in terms of stress and strain and that the dimensions of the cylindrical elements, as well as the contact between them, could help to modify the stiffness structure as required. The tests performed have allowed to understand the sequence of physical phenomena that appears at different strain rates and how they affect the response of the structure. The results obtained may contribute to the knowledge of both polymeric auxetic structures and the use of additive manufacturing methods for such structures.
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•Development of a 3D auxetic polymeric cell by means of SLA manufacturing technique.•Experimental study of a polymeric auxetic structure under different loading rates.•Effect of the cells´ number and size on the mechanical response of the structure.•The cylinder-based unit cell could lead to control the stiffness of the structure.•Analysis of physical phenomena in the auxetic structure at different loading rates.
Abstract
This paper focuses on the fact that the water–energy nexus remains an irrelevant issue on the energy policy agenda and on the priorities of the energy leaders in Spain. This is a striking ...fact given that this takes place in the most arid country in Europe, where almost two-thirds of electricity generation would have to be halted in the absence of an adequate water supply. We contend that part of the explanation may lie in the lack of official statistics and inconsistent sources of information on the water–energy nexus in Spain. To illustrate this point, we provide examples of the uneven data available for one of the most intensive freshwater users in the thermoelectric sector in Spain: nuclear power plants. Our research demonstrates the need for improved indicators as policy instruments in the water–energy nexus in Spain since it is impossible to improve what cannot be measured.
In this work a constitutive relation for ice at high strain rates and an algorithm for its numerical integration are developed. This model is based on the Drucker–Prager plasticity criteria, which ...allows a different behavior in tension and in compression. In addition a failure criteria, based on pressure cut-offs, is implemented to describe the ice damage. In order to validate the constitutive model, numerical simulations were compared with experimental results, in which ice cylinders were impacted against a steel plate, allowing the measurement of the contact load. Three different numerical solvers are used in order to analyze its performance to appropriately modeling the ice behavior.
•A simplified Artificial bird has been proved to behave as literature review studies.•Radial expansion of the artificial bird has been studied.•Induced force by the impact has been measured using a ...Hopkinson tube.•The four numerical models benchmarked reproduce the impact force measured.•Numerical models commonly used are not capable to predict the radial expansion.
This work shows a combined experimental-numerical research in bird impact. In order to perform the experimental tests, a artificial bird has been prepared and impacted against a Hopkinson tube in a wide range of impact velocities (70–200 m/s). The Hopkinson tube was designed in order to measure the induced force transmitted in the tube by the impact. This force could be used to compare different experimental tests and also to validate the numerical models proposed. In addition, the whole process of impact was recorded by means of high speed video cameras. The images captured allow to perform the analysis of the bird kinematics during the impact. Numerically, in order to reproduce the high deformations experienced by the artificial bird in the impact process, the Smooth Particle Hydrodynamics (SPH) technique has been used. Concerning the artificial bird material behaviour, four different models were employed, combining the two material models and two equations of state most used in the literature. The four cases have been compared with the experimental measurements and benchmarked. After the analysis of the results, it can be concluded that the combined experimental-numerical methodology proposed successfully can be used to study and validate the numerical models for simulating the behaviour of soft impactor when subjected to high velocity impacts. It can be seen that the normal impact forces induced by the impact are reproduced adequately for all the numerical models. However the radial spreading of the soft impactor is not reproduced as adequately as the other cases, especially in low velocity impacts. This effect can be important to reproduce the radial distribution of pressures and the secondary impacts produced by this radial expansion.
Hydrodynamic ram (HRAM) is a phenomenon that occurs when a high-kinetic energy object penetrates a fluid-filled container. The projectile transfers its momentum and kinetic energy through the fluid ...to the surrounding structure, increasing the risk of catastrophic failure and excessive structural damage. This is of particular concern in the design of wing fuel tanks for aircraft since it has been identified as one of the important factors in aircraft vulnerability. In the present paper, the commercial finite-element code LS-DYNA has been used to simulate an HRAM event created by a steel spherical projectile impacting a water-filled aluminium square tube. Two different formulations (ALE and SPH) are employed to reproduce the event. Experimental tests which indicate the pressure at different points of the fluid, displacement of the walls and cavity evolution for different impact velocities are compared with the numerical results in order to assess the validity and accuracy of both ALE and SPH techniques in reproducing such a complex phenomenon.
Background
Current evidence supports the utility of simulation training for bedside procedures such as ultrasound‐guided jugular central venous catheter (CVC) insertion. However, a standardized ...methodology to teach procedural skills has not been determined yet. The aim of this study was to evaluate the effectiveness of a simulation‐based training program for improving novice technical performance during ultrasound‐guided internal jugular CVC placement.
Methods
Postgraduate year 1 (PGY‐1) residents from anesthesiology, emergency medicine, cardiology, ICU, and nephrology specialties were trained in four deliberate practice sessions. Learning objectives included principles of ultrasound (US), preparation (gown, glove, draping), procedural skills I (US scanning and puncture), and procedural skills II (catheter insertion). CVC technical proficiency was tested pre‐ and post‐training using hand‐motion analysis with the Imperial College Surgical Assessment Device (ICSAD) and a global rating scale (GRS).
Results
Thirty‐five PGY‐1 residents successfully completed the program. These novices' GRS scores improved significantly after the training (P < 0.001). Total path length measured with the ICSAD decreased significantly after the training (P = 0.008). Procedural time decreased significantly after training from 387 (310–501) seconds to 200 (157–261) seconds (median and interquartile range) (P = 0.029).
Conclusion
This simulation‐training program based on deliberate practice significantly increased the technical skills of residents in US‐guided short‐axis, out‐of‐plane internal jugular CVC placement. Data also confirm the validity of the ICSAD as an assessment tool for ultrasound‐guided internal jugular CVC placement learning.
In this work, the analysis of the impactor mass effect on the behaviour of carbon/epoxy woven laminates under low velocity impact is carried out. To this end experimental test were performed by means ...of a drop weigh tower in a range of energies varying from 10 to 110J, and using three different impactor masses. Two different laminate thicknesses were considered in order to take into account its possible influence. An analysis of the impact tests is performed using the Composite Structure Impact Performance Assessment Program, in order to observe the influence of impactor mass. Once impacted, the laminates were inspected by means of a C-Scan (to quantify the delamination extension) and a phased array ultrasonic system (to analyse the failure through the thickness); this non-destructive analysis will determine the influence of the impactor mass on the laminate failure.
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•Low time-consuming identification of modal parameters using 3D DIC.•Comparison of results applying 3D DIC and a traditional experimental method.•3D DIC allowed obtaining much ...smoother mode shapes, useful for damage localization.•Drastically reduced discrepancies of updated parameters with measured ones.•Very similar results of model updating based on the two experimental methods.
Model updating is usually based on the contrast between the modal characteristics predicted by the models and those experimentally identified. Traditional experimental methods are based on the use of contacting sensors, but more recently other techniques as 3D Digital Image Correlation (DIC) have also been used successfully. In this paper the results obtained by applying these alternative techniques are compared, to obtain physically-sound models of carbon/epoxy composite plates. Primarily a roving hammer exciting the plates at evenly distributed degrees of freedom (DoF), and a mono-axial accelerometer attached to a single DoF reference point, have been used for modal identification. Alternatively, high speed cameras were applied to measure full-field vibrations of the plates. 3D DIC allowed obtaining a lower number of natural frequencies but much smoother mode shapes and similar results for model updating. The experimental setup has been benchmarked using two different sets of plates varying thickness and ply stacking.
•The main failure mechanism that appears in the composite panels is delamination.•Most of the panels exhibit no-delaminated or almost full delaminated area.•A dimensionless variable that describes ...the influence of parameters is presented.
This work analyses the behaviour of carbon/epoxy unidirectional laminates subjected to high velocity impacts of ice spheres. To this end, ice projectiles were launched against composite laminates in a wide range of velocities (50 − 250 m/s). Two different ice diameters (40 and 50 mm) and two laminate thicknesses (4 and 6 mm) were considered. The internal damage was measured using both destructive and non-destructive techniques, which allow an accurate quantification of the delaminated area. Finally the influence of the different parameters considered on the damage of the laminate is analysed by means of a dimensionless variable.
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