Dynamic characterization and predictability analysis of wind speed and wind power time series in Spain wind farm

The renewable energy resources such as wind power have recently attracted more researchers’ attention. It is mainly due to the aggressive energy consumption, high pollution and cost of fossil fuels. In this era, the future fluctuations of these time series should be predicted to increase the reliability of the power network. In this paper, the dynamic characteristics and short-term predictability of hourly wind speed and power time series are investigated via nonlinear time series analysis methods such as power spectral density analysis, time series histogram, phase space reconstruction, the slope of integral sums, the   method, the recurrence plot and the recurrence quantification analysis. Moreover, the interactive behavior of the wind speed and wind power time series is studied via the cross correlation, the cross and joint recurrence plots as well as the cross and joint recurrence quantification analyses. The results imply stochastic nature of these time series. Besides, a measure of the short-term mimic predictability of the wind speed and the underlying wind power has been derived for the experimental data of Spain’s wind farm

Low Frequency Oscillations Suppression via CPSO based Damping Controller

In this paper, the Unified Power Flow Controller (UPFC) is enhanced with a Chaotic Particle Swarm Optimization (CPSO) Damping Controller in order to mitigate the Low Frequency Oscillations (LFO) in a Single Machine Infinite Bus (SMIB) power system. The designed damping controller is an optimized lead-lag controller, which extracts the speed deviation of the generator rotor and generates the output feedback signal, which aims to modulate the reference values of the UPFC normal controller to achieve the best damping of LFO. In order to examine the better damping option, the damping controller is applied to both series and shunt converter of the UPFC and the results are comprehensively compared in three different operating points. Simulation results are performed in MATLAB/Simulink in three different cases and a Performance Index (PI) analysis is carried out

Clinical learning environments (actual and expected): Perceptions of Iran University of Medical Sciences nursing students

Background: Educational clinical environment has an important role in nursing students' learning. Any difference between actual and expected clinical environment will decrease nursing students' interest in clinical environments and has a negative correlation with their clinical performance. Methods: This descriptive cross-sectional study is an attempt to compare nursing students' perception of the actual and expected status of clinical environments in medical-surgical wards. Participants of the study were 127 bachelor nursing students of Iran University of Medical Sciences in the internship period. Data gathering instruments were a demographic questionnaire (including sex, age, and grade point average), and the Clinical Learning Environment Inventory (CLEI) originally developed by Professor Chan (2001), in which its modified Farsi version (Actual and Preferred forms) consisting 42 items, 6 scales and 7 items per scale was used. Descriptive and inferential statistics (t-test, paired t-test, ANOVA) were used for data analysis through SPSS version 16. Results: The results indicated that there were significant differences between the preferred and actual form in all six scales. In other word, comparing with the actual form, the mean scores of all items in the preferred form were higher. The maximum mean difference was in innovation and the highest mean difference was in involvement scale. Conclusion: It is concluded that nursing students do not have a positive perception of their actual clinical teaching environment and this perception is significantly different from their perception of their expected environment

An Item Analysis of Written Multiple-Choice Questions: Kashan University of Medical Sciences

Background: Multiple Choice Questions (MCQs) are one of the most common types of exams used in evaluation of students in any educational setting. The question items making up these exams need to be examined if they are to meaningfully contribute to the student scores. Such characteristics are amenable to examination by item analysis. Objectives: The purpose of this research was to examine the quality of MCQs used in Nursing and Midwifery Faculty and to compare the results with the other faculties in Kashan University of Medical Science in the academic year 2008-2009. Materials and Methods: In this cross-sectional study, 101 multiple-choice exams were randomly chosen for the study, and 37 exams were selected from the faculty of nursing and midwifery. The difficulty, discrimination indices and Cronbach’s Alpha were calculated for every exam and then mean values for each index were calculated by LERTAL 5.0 software purchased from Assessment Systems Corporation of the United States. Results: A total of 7062 MCQs in the university and 1793 items in the faculty of nursing and midwifery presented to the students by different instructors were analyzed. The average of difficulty index of the faculty of nursing was 0.5. The discrimination index was 0.36, and the average of Alpha-Cronbach was 0.82 in the faculty of nursing. All the values were significantly better in the faculty of nursing and midwifery compared to the rest of the university. Conclusions: The difficulty index, the discrimination index and the Alpha-Cronbach values in the faculty of nursing were within the acceptable range recommended by experts in the field of educational measurement. However, some of the tests had values less than the recommended

Finite temperature calculations for the bulk properties of strange star using a many-body approach

We have considered a hot strange star matter, just after the collapse of a supernova, as a composition of strange, up and down quarks to calculate the bulk properties of this system at finite temperature with the density dependent bag constant. To parameterize the density dependent bag constant, we use our results for the lowest order constrained variational (LOCV) calculations of asymmetric nuclear matter. Our calculations for the structure properties of the strange star at different temperatures indicate that its maximum mass decreases by increasing the temperature. We have also compared our results with those of a fixed value of the bag constant. It can be seen that the density dependent bag constant leads to higher values of the maximum mass and radius for the strange star.Comment: 21 pages, 2 tables, 12 figures Astrophys. (2011) accepte

Structure of Neutron Star with a Quark Core

The equation of state of de-confined quark matter within the MIT bag model is calculated. This equation of state is used to compute the structure of a neutron star with quark core. It is found that the limiting mass of the neutron star is affected considerably by this modification of the equation of state. Calculations are carried out for different choices of the bag constant.Comment: 19 pages, 8 figure

Visualization of clinical teaching citations using social network analysis

Background: Analyzing the previous research literature in the field of clinical teaching has potential to show the trend and future direction of this field. This study aimed to visualize the co-authorship networks and scientific map of research outputs of clinical teaching and medical education by Social Network Analysis (SNA). Methods: We Identified 1229 publications on clinical teaching through a systematic search strategy in the Scopus (Elsevier), Web of Science (Clarivate Analytics) and Medline (NCBI/NLM) through PubMed from the year 1980 to 2018.The Ravar PreMap, Netdraw, UCINet and VOSviewer software were used for data visualization and analysis. Results: Based on the findings of study the network of clinical teaching was weak in term of cohesion and the density in the co-authorship networks of authors (clustering coefficient (CC): 0.749, density: 0.0238) and collaboration of countries (CC: 0.655, density: 0.176). In regard to centrality measures; the most influential authors in the co-authorship network was Rosenbaum ME, from the USA (0.048). More, the USA, the UK, Canada, Australia and the Netherlands have central role in collaboration countries network and has the vertex co-authorship with other that participated in publishing articles in clinical teaching. Analysis of background and affiliation of authors showed that co-authorship between clinical researchers in medicine filed is weak. Nineteen subject clusters were identified in the clinical teaching research network, seven of which were related to the expected competencies of clinical teaching and three related to clinical teaching skills. Conclusions: In order to improve the cohesion of the authorship network of clinical teaching, it is essential to improve research collaboration and co-authorship between new researchers and those who have better closeness or geodisk path with others, especially those with the clinical background. To reach to a dense and powerful topology in the knowledge network of this field encouraging policies to be made for international and national collaboration between clinicians and clinical teaching specialists. In addition, humanitarian and clinical reasoning need to be considered in clinical teaching as of new direction in the field from thematic aspects. © 2021, The Author(s)

Spin polarized liquid 3He

We have employed the constrained variational method to study the influence of spin polarization on the ground state properties of liquid $^3{\rm He}$. The spin polarized phase, we have found, has stronger correlation with respect to the unpolarized phase. It is shown that the internal energy of liquid $^3{\rm He}$ increases by increasing polarization with no crossing point between polarized and unpolarized energy curves over the liquid density range. The obtained internal energy curves show a bound state, even in the case of fully spin polarized matter. We have also investigated the validity of using a parabolic formula for calculating the energy of spin polarized liquid $^3{\rm He}$. Finally, we have compared our results with other calculations.Comment: 16 pages, 6 figure

Improving access to medicines for non-communicable diseases in rural India: a mixed methods study protocol using quasi-experimental design

Exit interview tool. Exit interview tool used in baseline survey of the ATM study. (PDF 150 kb

Promotion of access to essential medicines for Non-Communicable Diseases: Practical implications of the UN Political Declaration

Access to medicines and vaccines to prevent and treat non-communicable diseases (NCDs) is unacceptably low worldwide. In the 2011 UN political declaration on the prevention and control of NCDs, heads of government made several commitments related to access to essential medicines, technologies, and vaccines for such diseases. 30 years of experience with policies for essential medicines and 10 years of scaling up of HIV treatment have provided the knowledge needed to address barriers to long-term effective treatment and prevention of NCDs. More medicines can be acquired within existing budgets with efficient selection, procurement, and use of generic medicines. Furthermore, low-income and middle-income countries need to increase mobilisation of domestic resources to cater for the many patients with NCDs who do not have access to treatment. Existing initiatives for HIV treatment offer useful lessons that can enhance access to pharmaceutical management of NCDs and improve adherence to long-term treatment of chronic illness; policy makers should also address unacceptable inequities in access to controlled opioid analgesics. In addition to off-patent medicines, governments can promote access to new and future on-patent medicinal products through coherent and equitable health and trade policies, particularly those for intellectual property. Frequent conflicts of interest need to be identified and managed, and indicators and targets for access to NCD medicines should be used to monitor progress. Only with these approaches can a difference be made to the lives of hundreds of millions of current and future patients with NCDs