Power quality issues of 3MW direct-driven PMSG wind turbine

This paper presents power quality issues of a grid connected wind generation system with a MW-class direct-driven permanent magnet synchronous generator (PMSG). A variable speed wind turbine model was simulated and developed with the simulation tool of PSCAD/EMTDC. The model includes a wind turbine with one mass-model drive train model, a PMSG model and a full-scale voltage source back to back PWM converter. The converter controller model is employed in the dq-synchronous rotating reference frame and applied to both generator and grid sides. To achieve maximum power point tracking, a tip speed ratio method is applied in machine side, whereas DC voltage control is applied in grid side to achieve constant DC voltage. Due to wind fluctuation and power oscillation as a result of wind shear and tower shadow effects (3p), there will be a fluctuation in the output power and voltage. The concerned power quality issues in this work are Harmonics, power fluctuation and flicker emission. The measurements will be carried out under different wind speed and circumstances

Comparative power quality study of variable speed wind turbines

Due to the variabilities inherent to natural wind resources and the associated electronic power present, wind power produces fluctuations in the generated power and harmonic injection entering the electric grid. This paper compares power quality issues and the impact on the power system of wind reliant power systems when using two different types of variable speed wind generators: the direct-drive permanent-magnet synchronous generator, and the doubly-fed induction generator. First, it gives an overview of the system structure of each generator, and then both systems are simulated to determine their behavior and the consequent impact on power quality. The power quality aspects addressed are voltage fluctuation (Flicker), current harmonics, response to voltage dip, and voltage stability. After this assessment, the contribution of both generators to severe three-phase faults was tested and then, finally, fault-ride through

Tapping for pneumoperitoneum in neonates and infants

Purpose The aim of this study was to shed some light on the presence of pneumoperitoneum in neonates and infants and to present and evaluate our method for its treatment.Materials and methods This study included 33 patients diagnosed with pneumoperitoneum during 2004–2011, of whom 19 were girls and 14 were boys, and their ages ranged from 1 week to 5 months; 21 patients were neonates and seven of them were premature; two were aged less than 32 weeks and had mild pneumoperitoneum, which could be treated conservatively and five were aged between 32 and 34 weeks. Tapping was performed for all patients. Tapping can help in selection of patients with necrotizing enterocolitis needing exploration when the aspirate is bilious or feculent. Tapping could be performed as a temporary measure before exploration to decrease respiratory distress and the occurrence of abdominal compartment syndrome and also as a routine procedure in patients with pneumoperitoneum. Tapping is an easy procedure and can be performed with the patient in bed or in the incubator. Pneumoperitoneum is not an absolute indication for surgical exploration and a small subset of patients should be managed by laparotomy. Each patient with pneumoperitoneum should be assessed and categorized for tapping, placement of a tube drain, or surgical exploration. Pneumoperitoneum occurs in neonates more frequently than in infants, and most cases are idiopathic.Results A total of 29 patients were treated by tapping alone (in nine patients, tapping was performed once; in 13, it was performed twice, and in the other seven, it was performed three to four times). Rapid improvement in the general condition and respiratory distress occurred in most patients. Six patients (five neonates and one infant) were explored because of: (a) aspiration of a bile-stained or feculent fluid in two patients and (b) failure of conservative treatment in four patients.Conclusion Pneumoperitoneum occurs in neonates more than infants and most cases are idiopathic. Each case of pneumoperitoneum should be assessed and categorized for tapping, placement of a tube drain or surgical exploration. Pneumoperitoneum is not an absolute indication for surgical exploration and small subset of patients should be managed by laparotomy. Tapping is an easy job and can be done with the patient in bed or in the incubator. Tapping could be performed as a routine in cases of pneumoperitoneum. Tapping could be done as a temporary measure before exploration to decrease respiratory distress and abdominal compartment syndrome

Pattern of Presentation of Coronary Artery Disease in Hypertensive Patients

Background: Hypertension is a major risk factor for coronary artery disease (CAD) and left ventricular hypertrophy (LVH). Hypertensives have a threefold increase in cardiac death (due to either CAD or to cardiac failure).In Sudan hypertension complications were increasing in incidence and prevalence. Evaluating chest pain in hypertensive patients presents challenges because of left ventricular hypertrophy as a cause of chest pain besides CAD. There are limited data on different aspects of hypertensioncomplications.Objectives: To assess the CAD as a cause of chest pain, to see the pattern and severity of CAD and to find the correlation between ECG, ECHO and coronary angiography findings in hypertensive patientsMethodology: 135 known hypertensive patients presented with chest pain were assessed through ECG, ECHO and coronary angiography.Results: The participants’ ages ranged between 39 and 90 years, with mean age of 59 years .73.3% of them were found to have CAD. The left anterior descending (LAD) artery was the most involved one. Left main (LM) artery was the least involved. Electrocardiography (ECG) showed that LVH is found in more than 50%of patients with CAD. BMI was >25 in 41.5%. Percutaneous coronary intervention (PCI) was recommended in (31.4%), coronary artery bypass graft (CABG) in(21.6%). 33% and 25% of these consecutively have hypertension for 10 years or more.Conclusion: CAD is the main cause of chest pain in hypertensives. Aging, body mass index, duration and magnitude of hypertension and LVH have strong and frequent association with CAD

Effect of sodium chloride concentration on the functional properties of selectec Legume flours

Providing safe, nutritious, and wholesome food for poor and undernourished populations has been a major challenge for developing countries. This has led to the necessity of assembling complete food composition tables, yielding information about the traditional foods and on the functional properties of the plant foods that are consumed regularly in the developing countries. Sodium Chloride (NaCl) is the common salt used at household and industry levels to improve palatability of processed foods. Therefore, the main aim of the present study was to investigate the influence of different concentrations of NaCl on the functional properties of selected legume flours. The effect of increasing concentration of NaCl on the protein solubility, emulsifying and foaming properties of white bean, pigeon pea, cowpea and hyacinth bean were studied. The results revealed that the protein solubility of pigeon pea, cowpea and white bean flours significantly increased by increasing salt concentration and reached a maximum at 0.4 M NaCl (for pigeon pea and cowpea flours) and 0.6 M for white bean flour and then gradually decreased at higher salt concentration. The protein solubility profile of hyacinth bean fluctuated with the salt concentration, with the highest solubility at 0.6 M NaCl and lowest solubility at 0.4M NaCl. With the exception of white bean, the maximum emulsifying activity of all selected legume flours was found at 0.4 M NaCl whereas that of white bean was found at 0.2 M NaCl. Generally, with increasing salt concentration, the emulsifying activity slightly decreased for the legume flours, except for cowpea which fluctuated. Addition of NaCl significantly decreased the emulsion stability and foaming capacity of the four of selected legume with the maximum improvement being observed at 0.2 M NaCl, and then decreasing gradually at higher salt concentration. Significant improvement of foaming stability was observed when salt concentration increased. Based on the results of the present study the selected legume flour demonstrated good functional properties following the addition of NaCl, which makes these legume flours potential ingredients for application in salt containing foods.Keywords: functional properties, Legumes, Protein solubilityAfrican Journal of Food, Agriculture, Nutrition and Development, Volume 12 No.

Computer Modeling of Platinum Reforming Reactors

Usually, the reformate that is leaving any stage of the platinum reforming reactors in terms of hydrocarbon composition is assessed by laboratory analysis. The ideal composition can only be tested through theoretical means, which in most cases is avoided because of long computation time involved. This paper, instead of using a theoretical approach has considered a computer model as means of assessing the reformate composition for three-stage fixed bed reactors in platforming unit. This is done by identifying many possible hydrocarbon transformation reactions that are peculiar to the process unit, identify the operating data, mathematically model and programme their reaction rate equations using QBasic language. In this article outlet product rate of 311363.59 kg/hr in the first, second and third reactor was obtained by modeling 275 m3/h inlet feed rate of Bayton Rouge Naphtha in the Kaduna Refinery. A manual or theoretical calculated value of 311145.22 kg/hr of outlet product rate was obtained showing a slight deviation of 0.9%.  The authors are convinced that the written computer model could be applied in the process unit because it is accurate and less time consuming

Evaluation of handwritten Urdu text by integration of MNIST dataset learning experience

© 2019 IEEE. The similar nature of patterns may enhance the learning if the experience they attained during training is utilized to achieve maximum accuracy. This paper presents a novel way to exploit the transfer learning experience of similar patterns on handwritten Urdu text analysis. The MNIST pre-trained network is employed by transferring it's learning experience on Urdu Nastaliq Handwritten Dataset (UNHD) samples. The convolutional neural network is used for feature extraction. The experiments were performed using deep multidimensional long short term (MDLSTM) memory networks. The obtained result shows immaculate performance on number of experiments distinguished on the basis of handwritten complexity. The result of demonstrated experiments show that pre-trained network outperforms on subsequent target networks which enable them to focus on a particular feature learning. The conducted experiments presented astonishingly good accuracy on UNHD dataset

Assessment of Plasma Cystatin C among Sudanese Patients with Type II Diabetes Mellitus

Background: Cystatin C is mainly used as a biomarker of kidney function. It is freely filtered by glomerulus, and does not return to the blood stream or secreted by renal tubules. It has been suggested to be closer to the “ideal” endogenous marker.Objectives: To assess the plasma levels of cystatin c, creatinine clearance, blood HbA1C% and body mass index among Sudanese with type 2  Diabetes.Materials and methods: This is a case-control study conducted in diabetic centers in Khartoum state, Sudan, from March 2010 to November 2013. A total of 300 Sudanese patients with type2 diabetes (49% males and 51% females) as a test group, and 150 healthy subjects (48%males and 52%females) as a control group were enrolled in this study. Both groups were matched for gender and age. The plasma levels of Cystatin C, creatinine and blood HbA1c were measured using Nephelometry technique. Creatinine clearance was calculated for each participant. SPSS was usedfor analysis of data.Results: The means of the plasma levels of Cystatin C, HbA1c% and the body mass index (BMI) were significantly raised in the diabetic group  compared to the control group (p<0.05).There is significant moderate negative correlation between Cystatin C and creatinine clearance (r=0.69,p=0.015) in the diabetic group, and there is a significant strong positive correlation between the plasma levels of Cystatin C and HbA1c%(r=o.78, p=0.044).Conclusion: The present data indicates that among Sudanese patients with Type 2 Diabetes Mellitus, plasma levels of Cystatin C are significantly raised and has a significant strong positive correlation with glycated  haemoglobin % and a significant moderate negative correlation with creatinine clearance.Key words: Type 2 Diabetes, Cystatin C, Glycated Heamoglobin, Sudan

Effect of Fixatives' Temperatures on Subsequent Histochemical Staining

Background: Fixation is complex series of chemical events which differs for the different group of chemical substances found in tissues. Some chemical reactions, including those involved in fixation occur more rabidly at higher temperature.Objectives: Toassess the effect of varying fixatives' temperature on the quality of subsequent histochemical staining.Methods: Rabbit samples were collected including tongue tissue to demonstrate collagen fibers using Van Geison’s stain, and liver tissue to demonstrate cell morphology using Erlich’s haematoxylin. Specimens were divided into pieces; each sample was fixed in the following fixatives: formal saline, neutral buffer formalin (NBF), Carnoy’s and Bouin's fixative in different temperatures as follow 4C°, 25C°, 37C° and 60C°. There after, tissues were embedded in paraffin and cut sections into 5 micron and stained with Ehrlich’s hematoxylin and Van Gieson histochemical stains.Results: For Erlich’s heamtoxylin, formal saline gave the best result for tissues fixed at 60C°; NBF gave the best results at 37C° and 60C°. For Van Geison stain, formal saline and NBF the best results obtained at 37 C°.Conclusion: The study concluded that using 10% NBF, 10% Formal saline, Carnoy’s and Bouin’s fixatives applying different temperatures include 4C°, 25C°, 37C° and 60C° affect the subsequent histochemical staining of Ehrlich’s hematoxylin, and Van Gieson.Keywords: Fixatives, temperature, Van Geison, Erlich’sheamtoxylin, stai

High fluoride and low pH level have been detected in popular flavoured beverages in Malaysia

Objective: In children, excessive ingestion of fluoride from different sources including bottled drinking water and flavoured beverages or soft drinks can lead to the development of dental fluorosis. In addition, the pH level of beverages is important. Low pH can cause dental erosion. In this study we explore the fluoride content and pH level of certain popular beverages available in Malaysian supermarkets and hawkers' stalls. Methods: Bottled drinking water and selected popular flavoured packet drinks were purchased from a supermarket and the corresponding flavoured hawkers' drinks, from a hawker's stall in Kuala Lumpur. Fluoride and pH of the beverages were determined using digital fluoride meter and digital pH meter respectively. Results: It was found that fluoride content and pH level vary among the beverages. The mean fluoride content in both packet and hawkers' drinks (7.64±1.88 mg/L, 7.51±1.60 mg/L, respectively) was approximately 7 times higher than the bottled drinking water (1.05±0.35 mg/L). Among the beverages, the tea packet drink was found to contain the highest amount of fluoride (13.02±0.23 mg/L). The mean pH of bottled-drinking water was near neutral (6.96±0.17), but acidic for both supermarket (4.78.00±0.49) and hawkers' drinks (5.73±0.24). The lychee packet drink had the lowest pH level (2.97±0.03). Conclusions: Due to the wide variation of the fluoride content and pH level of the drinks tested in this study, it is recommended that steps should be taken to control the fluoride concentration and pH level in beverages if dental fluorosis and erosion are to be prevented. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down