7,184 research outputs found
Prediction of percentage of ferrite as a function of heat input in robotic gas metal arc welding of duplex stainless steel SAF 2205 Welds
The role of self-concept and expectations in academic achievement: A preliminary study
As early career students face new challenges at university, the relationship between L2 skills and academic success depends upon self-perception to a greater extent than previously assumed. Up to the moment, most levelling courses have focused on developing studentsâ skills in specific subjects in order to bridge the gap between the knowledge that the high school alumni have and university teachers expect them to possess. Yet, early academic failure remains elevated. For this reason, we have decided to focus our English Degree levelling course on academic strategies, expectations and procedures with the aim to disclose the role of studentsâ self-perception on L2 performance in an academic context. We have designed a two-staged method consisting of a survey and a standardized placement test to measure learnersâ self-perception. The results of both stages are measured by following a mixed method procedure, combining quantitative and qualitative analyses. Results show that there is a close relationship between studentsâ self-concepts, academic expectations, and final outcomes. When the learning of new contents occurs by means of a foreign language, the implications of learnersâ confidence and their academic awareness are even clearer. Therefore, we conclude that learnersâ self-concepts, and awareness of their academic expectations should play a key role in initial undergraduate training.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa TEC
UNEMPLOYMENT DURATION, UNEMPLOYMENT BENEFITS AND RECALLS
We use administrative micro-data to investigate exits from unemployment of benefit recipients in Spain. Because the data allow us to distinguish between transitions to a new job and recall to the same employer, we apply a competing risks model with observed and unobserved heterogeneity. We are also able to control for the type of benefit received by the worker: insurance benefit or assistance benefit. We find significant differences between the new job hazard and the recall hazard. Both hazard rates increase around the time that insurance benefit elapses. We also find that when larger firms recall unemployed workers they tend to do so faster than smaller firms. In general, our results are consistent with predictions derived from search and implicit contract models. They highlight the importance of taking into account the possibility of recall in the analysis of unemployment duration among unemployment benefit recipients.
Yield determination in olive hedgerow orchards. I. Yield and profiles of yield components in northâsouth and eastâwest oriented hedgerows
A study of the vertical distribution of flowering and fruit set and of components of yield (fruit numbers, fruit
size, and fruit oil content) was maintained for 2 years in NâS- and EâW-oriented olive hedgerows of comparable structure (row spacing 4m, hedgerow height to 2.5 m, width c. 1m) near Toledo, Spain (39.98N). Mean yield of the NâS orchard was 1854 kg oil/ha without difference between sides or years. Yield of the EâW orchard was greater in 2006, producing 2290 kg/ha, but only 1840 kg/ha in 2007, the same as the NâS orchard. The S side of the EâWorchard yielded more (59%) than the N side in 2007. In both orchards and years, most fruit was produced at 1.0â2.0m height and fruit density was the most influential component in these differences, reflecting more intense bud initiation in these upper layers. Other components that determined fruit number, fertile inflorescences, fruits per fertile inflorescence, and fruit drop were not significantly different between layers. Fruit characteristics depended on hedgerow position. In both NâS and EâW hedgerows, fruit high in the hedgerow was the largest, most mature, and with highest oil content. These differences
were more marked in NâS than in EâW hedgerows. Fruit growth and development were concentrated from the middle of
September until the end November. Oil content per fruit increased linearly during that period when 65% of final oil content was accumulated. Similar patterns were observed between sides. The results of yield and yield profiles are discussed in the general context of light interception. The results suggest the importance of hedgerow porosity, and distinct penetration patterns of direct-beam radiation through NâS and EâW hedgerows, as the basis for explanation of the high yield of the N side of EâW hedgerows
Approximations of the aggregated interference statistics for outage analysis in massive MTC
This paper presents several analytic closed-form approximations of the aggregated interference statistics within the framework of uplink massive machine-type-communications (mMTC), taking into account the random activity of the sensors. Given its discrete nature and the large number of devices involved, a continuous approximation based on the GramâCharlier series expansion of a truncated Gaussian kernel is proposed. We use this approximation to derive an analytic closed-form expression for the outage probability, corresponding to the event of the signal-to-interference-and-noise ratio being below a detection threshold. This metric is useful since it can be used for evaluating the performance of mMTC systems. We analyze, as an illustrative application of the previous approximation, a scenario with several multi-antenna collector nodes, each equipped with a set of predefined spatial beams. We consider two setups, namely single- and multiple-resource, in reference to the number of resources that are allocated to each beam. A graph-based approach that minimizes the average outage probability, and that is based on the statistics approximation, is used as allocation strategy. Finally, we describe an access protocol where the resource identifiers are broadcast (distributed) through the beams. Numerical simulations prove the accuracy of the approximations and the benefits of the allocation strategy.Peer ReviewedPostprint (published version
Yield determination in olive hedgerow orchards. II. Analysis of radiation and fruiting profiles
Profiles of fruit density, fruit size, and oil content were measured on 12 occasions in 7 olive orchards in Spain and
2 in Australia. Orchard structure varied widely. Height ranged from 2.0 to 5.5 m, row spacing from 3 to 6 m, and canopy width from 0.7 to 3m. Most orchards were oriented northâsouth (NâS) but one in Spain was oriented close to eastâwest (EâW)(208NEâSW). All orchards in Spain were cv. Arbequina, and in Australia they were cvv. Barnea and Picual. Analyses with a model of interception and transmission that estimated interception by individual sides of hedgerows revealed that fruit size and oil content were strongly related to intercepted radiation during the month before harvest across all orchards. Relationships were also evident between fruit density and interception but varied among orchards and years, indicating the importance of other environmental and probably physiological effects. In NâS orchards of cv. Arbequina, average fruit size and oil content increased linearly from 0.40 g (dry weight) to 0.72 g, and from 36 to 49% (of dry weight), as daily intercepted PAR increased from 6 to 25 mol/m2 (15â60% of horizontally incident radiation). The general principles of response extended to EâW orchards. There, it was shown that generally large fruit with high oil content on S sides was consistent with the plateau responses to radiation evident in the more extensive NâS data. On the N side, however, and accounting for transmission through the hedgerow, both fruit size and oil content were greater than in positions intercepting equivalent radiation inNâS orchards. Examples are provided of the utility of responses of fruit density, size, and oil content in establishing combinations of row height, row width, and row distance to improve or maintain productivity in some of the orchards included in the study
Technical and didactic knowledge of the moodle LMS in Higher Education: beyond functional use
Higher education institutions at the international level have seen
the need to adopt and integrate information and communication
technologies to meet the opportunities and challenges of innovation
in teaching and learning processes. This logic has led to the
implementation of virtual learning environments called âLearning
Management Systemsâ, the functionalities of which support
flexible and active learning under a constructivist approach.
This study measured didactic and technological use of Moodle
and its implications in teaching from a quantitative approach
by administering a questionnaire to a sample of 640 higher
education teachers. Some guiding questions were as follows:
Are teachers using the Moodle platform for didactic purposes?
What strategies, resources and tools are teachers using, and
what do they contribute to student-centred teaching? Are teaching
strategies that are focused on collaboration, interaction and
student autonomy promoted? The results coincide with those of
other studies, confirming an instrumental and functional use of the
platform, which is mainly being used as a repository for materials
and information, while its pedagogical use remains limited. This is
becoming a problem in higher education institutions, something
that requires debate and reflection from a systemic perspective on
the adoption and integration of technology in the classroo
An empirical study of power consumption of Web-based communications in mobile phones
Currently, mobile devices are the most popular
pervasive computing device, and they are becoming the primer way for Web access. Energy is a critical resource in such pervasive
computing devices, being network communication one of the primary energy consuming operations in mobile apps. Indeed, web-based communication is the most used, but also energy demanding. So, mobile web developers should be aware of how much energy consumes the different web-based communication alternatives. The goal of this paper is to measure and compare the
energy consumption of three asynchronous Web-based methods in mobile devices. Our experiments consider three different Web applications models that allow a web server to push data to a browser: Polling, Long Polling and WebSockets. The obtained
results are analyzed to get more accurate understanding of the impact in energy consumption of a mobile browser for each
of these three methods. The utility of these experiments is to show developers what are the factors that influence the energy consumption when different web-based asynchronous communication
is used. With this information mobile web developers
could reduce the power consumption of web applications on
mobile devices, by selecting the most appropriate method for
asynchronous server communication.MUniversidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
Poly-Harmonic Distortion Model Extraction in Charge-Controlled One-Port Devices
A charge-controlled, one-port device is used to
describe and discuss the extraction procedure of a Poly-Harmonic Distortion (PHD) model in detail. For this case, both voltage and current waveforms are shown to be enough to fully characterize the PHD model. It is also shown that all the information
specifically required for this PHD model definition can be stored in the Fourier coefficients of the incremental conductance and capacitance. The results are validated by comparing them with those obtained using a commercial circuit simulation tool.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
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