Modeling of wind energy conversion system using PSCAD/EMTDC

This paper aims to model a complete wind energy conversion system (WECS) connected to a grid. The motivation comes from the Distributed Generation System (DGS) installed at the Renewable Energy Lab at UMass Lowell. The objective of this work is to develop universal and standardized manufacturer independent textbook models. Manufacturer specific models are more accurate and detailed, but proprietary and non-disclosure agreements become an issue for research purposes. Since the wind turbines installed in the lab are VSWT (Variable Speed Wind Turbine) with Permanent Magnet Synchronous Generators (PMSG), so such a turbine system is modeled to represent them in general. PMSG requires very less maintenance and has high efficiency since it doesn't have rotor current and is used without a gearbox. Further, there are two more advantages: first, it has the capability of variable speed control due to the fact that its rotor speed can change in a large range; second, it's excitation system is independent of the grid and require any other excitation source. In addition to the turbine generator, other main components of WECS are also modeled namely: wind source model, wind turbine, permanent magnet synchronous generator and AC/DC/AC control. The equations governing these models are also discussed. The entire generation system is implemented on PSCAD/EMTDC and integrated to a grid and a basic fault analysis is done under different conditions. The proposed model can be used for research purposes on distributed generation issues. This model provides a good software simulation test bed for further research

Emergence of world-stock-market network

In the age of globalization, it is natural that the stock market of each country is not independent form the other markets. In this case, collective behavior could be emerged form their dependency together. This article studies the collective behavior of a set of forty influential markets in the world economy with the aim of exploring a global financial structure that could be called world-stock-market network. Towards this end, we analyze the cross-correlation matrix of the indices of these forty markets using Random Matrix Theory (RMT). We find the degree of collective behavior among the markets and the share of each market in their structural formation. This finding together with the results obtained from the same calculation on four stock markets reinforce the idea of a world financial market. Finally, we draw the dendrogram of the cross-correlation matrix to make communities in this abstract global market visible. The dendrogram, drawn by at least thirty percent of correlation, shows that the world financial market comprises three communities each of which includes stock markets with geographical proximity

Effect of the timing of initial feeding on growth and survival of Persian sturgeon (Acipenser persicus) larvae

Effect of the timing of first feeding (9, 10, 11, 12 and 13 days post hatch) with a live food (Artemia naupli) on Persian sturgeon was examined at 17.7±0.8 and 18.1±0.4°C. The results showed that the timing of first feeding affected on weight, length, length-weight ratio and specific growth rate, but one day delay in the timing of initial feeding doesn't affect on the survival and two days delay in the timing of initial feeding doesn't affect on the condition factor. Results of this research showed that some factors such as weight, length, length-weight ratio and specific growth rate, are more suitable than survival and condition factor for exhibiting of effects of delay in the starting time of initial feeding in Persian sturgeon fish larvae. Thus it is better that the initial feeding of Persian sturgeon at 17.7±0.8 and 18.1 ±0.4°C started on 12 and 9 days after hatching, respectively, as well as more delay in initiating exogenous feeding has negative effects on growth of larvae

Evaluation of different dietary protein and energy levels on growth performance and body composition of narrow clawed crayfish (Astacus leptodactylus)

Nine practical diets containing increasing percentages of crude protein (CP) and energy (30%, 35%, 40% and 300kcal/100g, 370kcal/100g and 450kcal/100g) were fed to narrow clawed crayfish (mean individual weight=17±2.3 g) during an 8 week feeding trial. Weight Gain, Feed conversion ratio (FCR), Protein Efficiency Ratio (PER), Net Protein Utilization (NPU), Daily Food Consumption (DFC) and body composition of tail-muscle meat of narrow clawed crayfish were determined. At the conclusion of the experiment, comparing the growth parameters in response to interaction between protein and energy levels demonstrated that dietary number 2 (30/370) resulted in higher WG, NPU, PER, and the lowest FCR whereas dietary number 3 (30:450) showed higher SGR and DFC. Comparison of the body composition results indicates the greatest amount of protein absorption in diet number 2 (30/370). Results from this study indicate that narrow clawed crayfish can be fed a practical diet containing 30% protein and 370 Kcal/100gr. Reducing CP levels in narrow clawed crayfish diets may help reduce operating costs and thereby increase producers’ profits

Factors that influence marital intimacy: a qualitative analysis of Iranian married couples

Intimacy is a key factor contributing to marriage satisfaction, marriage quality, marriage stability, and marriage functioning. Despite significant attention on marital intimacy, the focus of most research has either centered on the functions of marital intimacy or aspects of the construct in marriage satisfaction. Factors that influence couple intimacy are largely overlooked. Existing studies mainly have used cross-sectional survey data. Very little exists on intimacy factors in non-western cultures. No previous research has explored intimacy through the lens of intimate couples. Therefore, this qualitative study is an attempt to investigate factors that enhance the marital intimacy of Iranian couples and introduce culture-sensitive factors. Using criterion-based purposive sampling, 14 females and males (i.e., seven intimate couples) were selected to participate in the present study, and the con-sensual qualitative research method was utilized to analyze data from the semi-structured interviews and personal diaries. Results demonstrated that factors enhancing marital intimacy were (i) family, (ii) shared time/length of marital relationship , (iii) reciprocity in self-sacrifice (iv) gratitude (v) new shared activity, (vi

A detailed systematic anatomical study of monocephalic conjoined symmetric twin lambs

A case of conjoined twins with monocephalus, thoracopagus, partial abdominopagus, tetrabrachius and tetrascelus in lambs complicated with several defects of skeletal, cardiovascular, gastrointestinal, and urogenital systems is reported. The twins were dead and delivered by cesarean section. This case report highlights the detailed anatomical study of defects in different systems due to an abnormal birth defect.Keywords: Monocephalus, Sheep, Tetrabrachius, Tetrascelus, Thoracopagu

Effects of Selenium Supplementation on Metabolic Status in Patients Undergoing for Coronary Artery Bypass Grafting (CABG) Surgery: a Randomized, Double-Blind, Placebo-Controlled Trial

This study was carried out to evaluate the effects of selenium supplementation on glycemic control, lipid profiles, and biomarkers of inflammation and oxidative stress in patients undergoing for coronary artery bypass grafting (CABG) surgery. This randomized, double-blind, placebo-controlled trial was performed among 33 patients undergoing for CABG surgery, aged 40�85 years old. Subjects were randomly allocated into two groups to intake either 200 μg/day selenium supplements as selenium yeast (n = 17) or placebo (n = 16) for 4 weeks. Glycemic control, lipid profiles, and biomarkers of inflammation and oxidative stress were assessed at baseline and at the end of trial. After the 4-week intervention, selenium supplementation significantly decreased fasting plasma glucose (FPG) (β, 6.76 mg/dL; 95 CI, � 13.13, � 0.40; P = 0.03), insulin (β, � 1.14 μIU/mL; 95 CI, � 2.01, � 0.28; P = 0.01); homeostasis model of assessment-estimated insulin resistance (HOMA-IR) (β � 0.35; 95 CI, � 0.62, � 0.08; P = 0.01); and total-/HDL-cholesterol ratio (β � 0.31; 95 CI, � 0.51, � 0.09; P = 0.008); and significantly increased HDL-cholesterol levels (β, 2.72 mg/dL; 95 CI, 0.89, 4.55; P = 0.005) compared with the placebo. Moreover, selenium supplementation led to a significant reduction in high-sensitivity C-reactive protein (hs-CRP) (β, � 0.68 mg/L; 95 CI, � 1.18, � 0.17; P = 0.01) and malondialdehyde (MDA) (β, � 0.27 μmol/L; 95 CI, � 0.47, � 0.07; P = 0.009), and a significant elevation in total glutathione (GSH) levels (β, 77.33 μmol/L; 95 CI, 56.11, 98.55; P < 0.001) compared with the placebo. Selenium supplementation did not affect other metabolic profiles. Overall, our study demonstrated that selenium supplementation for 4 weeks to patients undergoing for CABG surgery had beneficial effects on FPG, insulin, HOMA-IR, total-/HDL-cholesterol ratio, HDL-cholesterol, hs-CRP, GSH, and MDA levels, but did not affect other metabolic profiles. Clinical trial registration number: http://www.irct.ir: IRCT2017090533941N22. © 2019, Springer Science+Business Media, LLC, part of Springer Nature

Articulation features, phonological awareness, and language skills in children with speech sound disorders

Background and purpose: Speech sound disorders are the most common speech disorders in children which are associated with other problems and can lead to social problems, attention deficit and academic skills challenges. The aim of this study was to investigate articulation characteristics, phonological awareness and language skills in children with speech sound disorders. Materials and methods: In a descriptive analytical study 24 children with speech sound disorder and 16 normal children were participated. The patients were selected from speech therapy clinics and the controls were chosen from nurseries based on convenience sampling. Speech production, oromotor and language skills were assessed by P-DEAP, TOLD-P3 and Phonological Awareness Test, respectively. Data was analyzed in SPSS ver. 20 using independent-samples t-test. Results: There were significant differences between the two groups in phonological awareness skills (except blending phonemes (P= 0.2)), syntax (P=0.002), semantic (P=0.009), spoken language (P=0.003), listening (P=0.002), organizing (P=0.004), and speaking (P=0.02). Conclusion: Children with speech sound disorders had atypical errors demonstrating weaker performance in language skills such as syntax, semantic, and phonological awareness compared to normal children. According to this study despite evaluating speech production it is necessary to assess language skills and phonological awareness in children with speech sound disorders. © 2016, AMazandaran University of Medical Sciences. All rights reserved

Effect of Listeria monocytogenes inoculation, sodium acetate and nisin on microbiological and chemical quality of grass carp Ctenopharyngodon idella during refrigeration storage

In this study, the microbiological quality and lipid oxidation of the grass carp (Ctenopharyngodon idella) fillets treated by dipping in sodium acetate (0, 1 and 3%), nisin (0, 0.1 and 0.2%) or their combination were evaluated during 16 days of refrigeration storage. Antilisterial effect of nisin was enhanced with the increased concentration of sodium acetate. With increasing the concentrations of sodium acetate, mesophilic counts were lower but regarding nisin, better results were obtained by applying 0.1% nisin. Greater inhibition of mesophile bacteria was observed when combination treatment was used. The number of lactobacillus was lower when higher concentrations of sodium acetate and nisin were used. Peroxide, TBA and total viable base nitrogen (TVB-N) values were lower in the samples treated with both nisin and sodium acetate and higher results were obtained in the combination treatments.Key words: Listeria monocytogenes, nisin, sodium acetate, microbial quality, chemical quality, grass carp