Miracle-dz/UniFAR-FTUs huggingface dataset:
Dynamic Modelling of a Wind Farm and Analysis of Its Impact on a Weak Power System

Wind power generation is considered the most economic viable alternative within the portfolio of renewable energy resources. Among their advantages are the large number of potential sites for plant installation and the rapidly evolving technology with many suppliers offering from the individual turbine set to even turnkey projects. On the other hand, wind energy projects entail high initial capital costs and, in operation, a lack of controllability on the discontinuous or intermittent resource. In spite of these disadvantages, their incorporation is growing steadily, a fact that is making the utilities evaluate the various influencing aspects of wind power generation onto power systems. Throughout the world there are large scarcely populated areas with good wind power potential where the existing grids are small or weak, due to the small population. A typical example is the large expanse of the Argentine Patagonia, with small cities clustered on the coastal areas and the Andean valleys. In these areas the capacity of the grid can very often be a limiting factor for the exploitation of the wind resource. One of the main problems concerned with wind power and weak grids is the voltage fluctuations. Several factors contribute to the voltage fluctuations in the terminals of a wind turbine generator (Suvire & Mercado, 2006; Slootweg & Kling, 2003; Ackermann, 2005; Chen & Spooner, 2001; Mohod & Aware, 2008; Smith et al., 2007): the aerodynamic phenomena, i.e., wind turbulence, tower shadow, etc.; the short-circuit power at the connection points; the number of turbines and the type of control. Besides, wind turbines may also cause voltage fluctuations in the grid if there are relatively large current variations during the connection and disconnection of turbines. With these aspects in mind, it turns necessary to ponder the information stemming from models that simulate the dynamic interaction between wind farms and the power systems they are connected to. Such models allow performing the necessary preliminary studies before connecting wind farms to the grid. The purpose of this chapter is to show by means of simulations the voltage fluctuations caused by a wind farm in a weak power system. A model for dynamic performance of wind farms is presented, which takes into account the dynamic behaviour of an individual wind turbine and the aggregation effect of a wind farm (i.e., the larger the wind farm, the smoother the output waveforms). In addition, the wind speed model and wind turbine models are briefly presented. Validation of models and simulations of the interactions between the wind farm and the power system are carried out by using SimPowerSystems of SIMULINK/MATLABTM.
Swedish Lower Secondary School Teachers' Perceptions and Experiences Regarding Homework.

This study investigates homework in Swedish lower secondary schools: teachers' perceptions and experiences about it and their understanding of its potentials and challenges for students' learning and development. Data collected through an online survey (N = 201) mixed standardized questions and open questions. Descriptive statistics and qualitative interpretive principles fueled data processing and analysis. The main result indicated that most teachers assign homework and believe it will benefit students' learning when it addresses consolidating and reinforcing knowledge already taught and increases skills through repetition. They regard appropriation and variation of homework and feedback as important to homework activities and effects. The teachers experience uneven attitudes to and outcomes of homework among students. Most schools organize homework assistance activities to smooth out this unevenness and to improve homework completion and quality. The findings highlight the educational implications of critical reflections on the design of homework and the quality of homework assignments.
Socio-Demographic Determinants of Place of Delivery among Women of Reproductive Age ( 15-49 Years ) Seeking Child Welfare Services in Kandara Subcounty , Murang ’ a Gachathi

Maternal and child mortalities are among major health problems facing developing countriesincluding Kenya. Most of these deaths can be avoided by utilization of maternity healthcare services by women seeking delivery care services from health professionals. The main objective of the study was to assess the socio-demographic determinants that influence the place of delivery among mothers seeking Child Welfare services in sampled health facilities in Kandara Sub County. The study adopted a facility-based cross-sectional survey design using an interview schedule and Key Informant Interview (KII) to collect quantitative and qualitative data respectively. The researcher pretested data tools in three health facilities that did not participate in the final study. On ethical issues, the researcher was cleared by the University Ethics Committee and by the administration of Murang’a County and of Kandara Sub County. The researcher ensured respondents privacy, confidentiality and anonymity throughout the entire research process. The study population comprised of mothers recently delivered within a 12 month prior to the study and seeking Child Welfare services at the selected health facilities in the Sub County. Simple random and purposeful sampling methods were used to identify the facilities which participated in the study. The desired sample size was 352 respondents which wascalculated using Fishers et al 1998 formula. Respondents were identified using systematic random sampling method. Descriptive statistic was used to represent analyzed data. A Computer software, Statistical Package for Social Sciences (SPSS) version20.0was used to analyze the quantitative data. Content analysis Qualitative data done and results triangulated with the quantitative data as per the study variables. The study found that social demographic determinants(p value of 0.034) had a significant positive influence on the choice of place of delivery.
Robust Commuter Movement Inference from Connected Mobile Devices

The preponderance of connected devices provides unprecedented opportunities for fine-grained monitoring of the public infrastructure. However while classical models expect high quality application-specific data streams, the promise of the Internet of Things (IoT) is that of an abundance of disparate and noisy datasets from connected devices. In this context, we consider the problem of estimation of the level of service of a city-wide public transport network. We first propose a robust unsupervised model for train movement inference from wifi traces, via the application of robust clustering methods to a one dimensional spatio-temporal setting. We then explore the extent to which the demand-supply gap can be estimated from connected devices. We propose a classification model of real-time commuter patterns, including both a batch training phase and an online learning component. We describe our deployment architecture and assess our system accuracy on a large-scale anonymized dataset comprising more than 10 billion records.
3 Development of Resonant Magnetic Field Microsensors : Challenges and Future Applications

Microelectromechanical Systems (MEMS) integrate electrical and mechanical components with feature sizes in the micrometer-scale, which can be fabricated using integrated circuit batch-processing technologies (Gad-el-Hak, 2001). The development of devices using MEMS has important advantages such as small size, light weight, low-power consumption, high sensitivity and high resolution (Herrera-May et al., 2009a). MEMS have allowed the development of several microdevices such as accelerometers (L. Li et al., 2011), gyroscopes (Che et al., 2010), micromirrors (Y. Li et al., 2011), and pressure sensors (Mian & Law, 2010). Recently, some researchers (Mohammad et al., 2010, 2011a, 2011b; Wang et al., 2011) have integrated acceleration, pressure or temperature sensors using MEMS. A potential market for MEMS will include magnetic field microsensors for applications such as automotive industry, telecommunications, medical and military instruments, and consumer electronics products (Lenz & Edelstein, 2006). The most sensitive magnetic field sensor is the Superconducting Quantum Interference Device (SQUID), which has a resolution on the order of several femptoteslas (JosephsFranks et al., 2003). It operates at low temperature based on two effects: flux quantization and Josephson effects. This sensor needs a sophisticated infrastructure that increases its size and cost, which limits its commercial applications. Hall effect sensors have a low cost, small size, and a power consumption from 100 to 200 mW. They are fabricated on standard Complementary Metal-Oxide Semiconductor (CMOS) technology and can measure either constant or varying magnetic field between temperature ranges from -100 to + 100 oC (Ripka & Tipek, 2007). Nevertheless, Hall effect sensors have a low resolution from 1 to 100 mT and require temperature compensation circuits (Popovic, 2004). Fluxgate sensors can measure static or low frequency magnetic field with a resolution of 100 pT (Ripka & Tipek, 2007). They have a size of several millimeters and a power
Model-Based Predictive Control for the Exhaust Gas Cycle of an Oxyfuel-Process

Abstract The global environmental warming which is discussed these days is, at the opinion of many experts, amongst other things ascribed to human induced carbon dioxide emissions which intensify the greenhouse effect. To face and overcome the negative consequences like environmental disasters, the rising mean sea level and others, new power plant concepts are researched and developed. In this article a novel, zero emission, oxyfuel power plant concept is discussed. Due to the novelty of the process it is examined in calculations, simulations and laboratory tests by a research group at RWTH Aachen university and does not exist in reality by now. Besides a conventional water cycle, an exhaust gas cycle has a major function in the process. The operation of the exhaust gas cycle requires an automation concept. In this paper an object-oriented model is used as a basis for examining the process behaviour and developing a controller for the multivariable and strongly coupled system. For the sliced exhaust gas cycle a model-based predictive controller is introduced. A parameter study presents the impact of selected controller parameters.
Data fusion of high-resolution satellite imagery and GIS data for automatic building extraction

Automatic building extraction in urban areas has become an intensive research as it contributes to many applications. High-resolution satellite (HRS) imagery is an important data source. However, it is a challenge task to extract buildings with only HRS imagery. Additional information and prior knowledge should be incorporated. c A new approach building extraction is proposed in this study. Data sources are QuickBird imagery and GIS data. The GIS data can provide prior knowledge including position and shape information, and the HRS image has rich spectral, texture features. To fuse these two kinds of features, the HRS image is first segmented into image objects. A graph is built according to the connectivity between the adjacent image objects. Second, the position information of GIS data is used to choose a seed region in the image for each GIS building object. Third, the seed region is grown by adding its neighbor regions constrained by the shape of GIS building. The performance is evaluated according to the manually delineated buildings. The results show performance of 0.142 in miss factor and detection percentage of 89.43% (correctness) and the overall quality of 79.35%.
Evolutionary transitions to cooperative societies in fishes revisited

Unravelling the evolution of complex social organization in animals is an important aim, not least because it helps to understand the evolutionary roots of human sociality. Recent advances in comparative methods allow to approach this question in a phylogenetic context. The validity of such comparative approaches depends strongly on the quality of information regarding the behaviour, sociality, and reproduction of animals in natural systems, and on the quality of the phylogenetic reconstruction. Applying a novel comparative approach, a recent study of Dey et al. (2017, Nature Ecology & Evolution, 1, 137) concluded that evolutionary transitions to cooperative breeding in cichlid fishes were not associated with the social mating pattern. Here we argue that this result was adversely affected by equivocal classifications of mating patterns, and inadequate phylogenetic data. In order to illustrate the impact of the mating system misclassifications, we scored mating patterns as reported in the original literature and re‐analysed the dataset based on Dey et al.’s tree topology. The result suggests that the mating system does in fact significantly explain the evolutionary transition to cooperative breeding in lamprologine cichlids, but we submit that a reliable conclusion cannot be reached before improving the behavioural information and the underlying phylogenetic reconstruction. The problems identified in this case study are not unique and we urge caution in the interpretation of results from comparative phylogenetic studies in general. We do agree with Dey et al. (2017) though that the lamprologine cichlids of Lake Tanganyika may constitute a fundamental test case for the theory of social evolution, but better information on their behaviour and phylogenetic relationships is needed to allow meaningful analyses.
Closed-loop identification of cardiovascular regulatory mechanisms

An approach to assessing closed-loop physiologic regulation by the analysis of multiple fluctuating physiologic signals, is presented. In particular, the couplings among heart rate, instantaneous lung volume, and arterial blood pressure have been studied. The procedure used consists of several steps. First, a block diagram model is constructed to display the assumed interrelationships among the measured data. Secondly, linear, constant-coefficient, autoregressive moving-average equations are written to describe each block in the model. Thirdly, the physiologic signals are recorded under conditions which ensure that their frequency content is broadband (e.g. during random interval breathing). Finally, the set of coefficients that result in an optimum least squares fit to the data is found. These parameters specify the transfer functions that correspond to the blocks in the original model. Preliminary results suggest that the time constants and sensitivities inferred from the estimated transfer functions agree with more invasive direct measurements reported in the literature,. <<ETX>>
Shapley Supercluster Survey: construction of the photometric catalogues and i-band data release

The Shapley Supercluster Survey is a multi-wavelength survey covering an area of ∼23 deg² (∼260 Mpc² at z = 0.048) around the supercluster core, including nine Abell and two poor clusters, having redshifts in the range 0.045–0.050. The survey aims to investigate the role of the cluster-scale mass assembly on the evolution of galaxies, mapping the effects of the environment from the cores of the clusters to their outskirts and along the filaments. The optical (ugri) imaging acquired with OmegaCAM on the VLT Survey Telescope is essential to achieve the project goals providing accurate multi-band photometry for the galaxy population down to m∗ + 6. We describe the methodology adopted to construct the optical catalogues and to separate extended and point-like sources. The catalogues reach average 5σ limiting magnitudes within a 3 arcsec diameter aperture of ugri = [24.4,24.6,24.1,23.3] and are 93 per cent complete down to ugri = [23.8,23.8,23.5,22.0] mag, corresponding to ∼m∗ r + 8.5. The data are highly uniform in terms of observing conditions and all acquired with seeing less than 1.1 arcsec full width at half-maximum. The median seeing in r band is 0.6 arcsec, corresponding to 0.56 kpc h⁻¹ 70 at z = 0.048. While the observations in the u, g and r bands are still ongoing, the i-band observations have been completed, and we present the i-band catalogue over the whole survey area. The latter is released and it will be regularly updated, through the use of the Virtual Observatory tools. This includes 734 319 sources down to i = 22.0 mag and it is the first optical homogeneous catalogue at such a depth, covering the central region of the Shapley supercluster.
Insights into the structure of the stable and metastable ( GeTe ) m ( Sb 2 Te 3 ) n compounds

Using first-principles calculations, we identify the mechanisms that lead to the lowest energy structures for the stable and metastable (GeTe){sub m}(Sb{sub 2}Te{sub 3}){sub n} (GST) compounds, namely, strain energy release by the formation of superlattice structures along of the hexagonal [0001] direction and by maximizing the number of Te atoms surrounded by three Ge and three Sb atoms (3Ge-Te-3Sb rule) and Peierls-type bond dimerization. The intrinsic vacancies form ordered planes perpendicular to the stacking direction in both phases, which separate the GST building blocks. The 3Ge-Te-3Sb rule leads to the intermixing of Ge and Sb atoms in the (0001) planes for Ge{sub 3}Sb{sub 2}Te{sub 6} and Ge{sub 2}Sb{sub 2}Te{sub 5}, while only single atomic species in the (0001) planes satisfy this rule for the GeSb{sub 2}Te{sub 4} and GeSb{sub 4}Te{sub 7} compositions. Furthermore, we explain the volume expansion of the metastable phase with respect to the stable phase as a consequence of the different stacking sequence of the Te atoms in the stable and metastable phases, which leads to a smaller Coulomb repulsion in the stable phase. The calculated equilibrium lattice parameters are in excellent agreement with experimental results and differ by less than 1% from the lattice parameters derivedmore » from a combination of the GeTe and Sb{sub 2}Te{sub 3} parent compounds. « less
Validation of a Screening Model for Referrals to Support Students with Hidden Disabilities in Higher Education

This study describes validation of a screening model for Referrals to Support with Hidden Disabilities in Higher Education. A screening model describes the screening procedures implemented by HEIs in all 8 public universities in Bosnia and Herzegovina. In the study, 5073 bachelor students were participated. There were 1371 (27%) male and 3702 (73%) female participants. In this research, the questionnaire for students in higher education was used. In order to validate the screening model, a multivariate method of exploratory factor analysis was applied. The intercorrelation of manifest variables was calculated, and on the basis of the obtained coefficients, the variables were selected for further analysis. The variables were subjected by calculating the coefficient of the inner consistency of the Cronbach alpha, and an estimate of the reliability of the variables was made by calculating the interstellar statistics. On the basis of the obtained results of factor analysis, a set of 28 manifest variables have been reduced to 15 variables that have satisfactory reliability and internal agreement, and it is justifiable to use them as a screening model. Findings support the requirement for a reliable and valid standardized assessment procedure for HEIs, which would provide equitable access to an initial diagnosis.
The Stochastic Dynamics of Rectangular and V-shaped Atomic Force Microscope Cantilevers in a Viscous Fluid and Near a Solid Boundary

Using a thermodynamic approach based upon the fluctuation-dissipation theorem we quantify the stochastic dynamics of rectangular and V-shaped microscale cantilevers immersed in a viscous fluid. We show that the stochastic cantilever dynamics as measured by the displacement of the cantilever tip or by the angle of the cantilever tip are different. We trace this difference to contributions from the higher modes of the cantilever. We find that contributions from the higher modes are significant in the dynamics of the cantilever tip-angle. For the V-shaped cantilever the resulting flow field is three-dimensional and complex in contrast to what is found for a long and slender rectangular cantilever. Despite this complexity the stochastic dynamics can be predicted using a two-dimensional model with an appropriately chosen length scale. We also quantify the increased fluid dissipation that results as a V-shaped cantilever is brought near a solid planar boundary.
Scaling Green-Kubo Relation and Application to Three Aging Systems

The Green-Kubo formula relates the spatial diffusion coefficient to the stationary velocity autocorrelation function. We derive a generalization of the Green-Kubo formula valid for systems with long-range or nonstationary correlations for which the standard approach is no longer valid. For the systems under consideration, the velocity autocorrelation function $\langle v(t+\tau) v(t) \rangle$ asymptotically exhibits a certain scaling behavior and the diffusion is anomalous $\langle x^2(t) \rangle \simeq 2 D_\nu t^{\nu}$. We show how both the anomalous diffusion coefficient $D_\nu$ and exponent $\nu$ can be extracted from this scaling form. Our scaling Green-Kubo relation thus extends an important relation between transport properties and correlation functions to generic systems with scale invariant dynamics. This includes stationary systems with slowly decaying power law correlations as well as aging systems, whose properties depend on the the age of the system. Even for systems that are stationary in the long time limit, we find that the long time diffusive behavior can strongly depend on the initial preparation of the system. In these cases, the diffusivity $D_{\nu}$ is not unique and we determine its values for a stationary respectively nonstationary initial state. We discuss three applications of the scaling Green-Kubo relation: Free diffusion with nonlinear friction corresponding to cold atoms diffusing in optical lattices, the fractional Langevin equation with external noise recently suggested to model active transport in cells and the L\'evy walk with numerous applications, in particular blinking quantum dots. These examples underline the wide applicability of our approach, which is able to treat very different mechanisms of anomalous diffusion.