Optimizing the Dynamic Performance of a Wind Driven Standalone DFIG Using an Advanced Control Algorithm

The article seeks to improve the dynamic performance of a standalone doubly fed induction generator (DFIG) which driven by a wind turbine, with the help of an effective control approach. The superiority of the designed predictive controller can be confirmed through evaluating the performance of the DFIG under other control algorithm, which is the model predictive direct torque control (MPDTC), model predictive current control (MPCC) as classic types of control. Firstly, the operating principles of the two controllers are described in details. After that, a comprehensive comparison is performed among the dynamic performances of the designed MPDTC, MPCC techniques and the predictive control strategy, so we can easily present the merits and deficiencies of each control scheme to be able to easily select the most appropriate algorithm to be utilized with the DFIG. The comparison is carried out in terms of system simplicity, dynamic response, ripples’ content, number of performed commutations and total harmonic distortion (THD). The results of the comparison prove the effectiveness and validation of our proposed predictive controller; as it achieves the system simplicity, its dynamic response is faster than that of MPDTC and MPCC, it presents a lower content of ripples compared to MPDTC and MPCC. Moreover, it can minimize the computational burden, remarkably. Furthermore, the numerical results are showing a marked reduction in the THD with a percentage of 2.23 % compared to MPDTC and 1.8 % compared to MPCC. For these reasons, it can be said that the formulated controller is the most convenient to be used with the DFIG to achieve the best dynamic performance

Investigation on Mechanical Properties of 302 L Stainless Steel Sheets under constant amplitude loading

 في هذه الدراسة تمت دراسة الخواص الميكانيكية مثل مقاومة الكلال وظاهرة نمو شق الكلال لصفائح الفولاذ المقاوم للصدأ 302 (S.SL بأسماك مختلفة (0.05 ملم، 0.1 مم و1.5 ملم). وأجريت التجارب العملية بالإضافة الى تقدير حياة الكلال باستخدام نموذج ووكر. تم إعداد العينات وفقا لمعيار المواصفات الامريكية العالمية E647-08. وأظهرت النتائج أن عينات الفولاذ بسمك 0.05 ملم أظهرت مقاومة الشد أعلى ولكن ليونة محدودة مع عدم وجود دليل واضح على مقاومة الخضوع بالمقارنة مع العينات الفولاذية الأخرى بأسماك 0.1 ملم و1.5 ملم.In this study, the mechanical properties i.e., fatigue strength and fatigue crack growth (FCG) behaviour of 302 L stainless steel (S.S.) sheets with different thicknesses (0.05 mm, 0.1 mm and 1.5 mm) were investigated. The experimental investigation as well as fatigue life predication by using Walker model were performed. The FCG specimens were prepared according to the ASTM E647-08 standard. The results showed that S.S. sheet with 0.05 mm thickness exhibited higher tensile strength but limited ductility with no clear evidence of yielding as compared to 0.1 mm and 1.5 mm thickness

Experimental Analysis of Fatigue Crack Path for Strained Functionally Graded Materials

This paper experimentally discusses crack paths in strained Functionally graded materials under constant loading conditions and vibration fatigue. The objective is to synthesize the body of knowledge on the stability of FGM. The article presents the development, production, and characterization of multi-Al (aluminum), Ni (nickel), and Titanium alloys. FGM it was successfully modified using the powder metallurgical technique. Five-layer FGM samples frequently utilize (Al, Ni), on one end and (Al-Ni-Ti) on the first. FGM sample mechanical characteristics have been investigated using wear and Fatigue testing. The Al/Ni/Titanium FGM compact specimen approaches the yield stress and ultimate stress values, which is regarded as a significant improvement in mechanical qualities with less weight. The test findings are for a constant amplitude load fully reversed with zero mean stress. The stress life approach examined three samples' fatigue characteristics and natural frequency under random vibration

Surface cracks growth for superalloy in a round bar under different loading

The main objective of this paper is to experimentally and numerically detect the surface cracks in the round bar for Ni-Al- 315 steel superalloy and calculate the crack depth which induces the sintering of these alloys. Several factors have contributed to surface defects, such as metallurgical defects and notches. The surface crack orientation can be estimated at the observed crack increase by using displacement. Various crack aspect ratios, a/b, ranging from 0.0 to 1.0, and relative crack depth, a/D, ranging from 0.2 to 0.4, are considered. The superalloy (Ni, Al and 315 steel) has been successfully modified utilizing the powder metallurgical process. The specimens are typically made up of Six layers, starting with (Al, Ni) across one side and ending with (Ni-Al- 315 steel) on another. Transmission electron microscopy (SEM) Instrument analysis has been used to detect the surface cracks and analyze the microstructure of superalloy used in detail using the X-pert analytical program

Selective immunoglobulin M deficiency in an adult with miliary tuberculosis: A clinically interesting coexistence. A case report and review of the literature

AbstractSelective immunoglobulin M (SIgM) deficiency is a rare form of dysgammaglobulinemia. Here we are reporting a 31year old man with multiple cervical and testicular abscesses who was investigated and found to have miliary tuberculosis (MTB) with primary SIgM deficiency (Serum IgM: 17.4mg/dL) and was treated aggressively with anti-tuberculous treatment

Synthesis and Spectral Analysis of Some Metal Ions Complexes with Mixed Ligands of Schiff Base and 1, 10-Phenanthroline

The free Schiff base ligand (HL1) is prepared by being mixed with the co-ligand 1, 10-phenanthroline (L2). The product then is reacted with metal ions: (Cr+3, Fe+3, Co+2, Ni+2, Cu+2 and Cd+2) to get new metal ion complexes. The ligand is prepared and its metal ion complexes are characterized by physic-chemical spectroscopic techniques such as: FT-IR, UV-Vis, spectra, mass spectrometer, molar conductivity, magnetic moment, metal content, chloride content and microanalysis (C.H.N) techniques. The results show the formation of the free Schiff base ligand (HL1). The fragments of the prepared free Schiff base ligand are identified by the mass spectrometer technique. All the analysis of ligand and its metal complexes are in good agreement with the theoretical values indicating the purity of Schiff base ligand and the metal complexes. From the above data, the molecular structures for all the metal complexes are proposed to be octahedra

Labor outcome among obese postdate women undergoing labor induction

Background: Maternal obesity and postdate pregnancy are common findings among pregnant women worldwide. We aimed to evaluate the influence of maternal obesity on the outcome of labor induction for postdate pregnant women.Methods: We conducted a prospective observational study to compare 118 obese women (≥30 kg/m2) with 118 non-obese women (<30 kg/m2) undergoing labor induction for postdate pregnancy (≥41 weeks). We induced all participants by a uniform protocol according to the Bishop score. The primary outcome measures were the cesarean delivery (CD) rate and the rate of failed induction. Secondary outcomes included prolonged induction- delivery time, prolonged first and second stage of labor, and rate of instrumental delivery. We performed a multivariate regression model to assess for the relation between obesity and the study outcomes of interest.Results: Cesarean delivery was significantly higher in obese women when compared with non-obese women (25.4% vs. 12.7%, p=0.02). Likewise, failed induction rate was significantly lower among non-obese women (5.1% vs. 14.4%. p=0.026). Obese women had increased odds for CD (adjusted odds ratio: 2.24; 95% confidence-interval: 1.13-4.33), failed induction rate (adjusted OR 2.96; 95% CI: 1.15-8.17), prolonged induction-delivery time (adjusted OR 4.57; 95% CI: 1.42-14.74), prolonged first stage of labor (adjusted OR 3.32; 95% CI: 1.07-9.89), prolonged second stage of labor (adjusted OR 4.21; 95% CI: 1.27-13.62), and rate of instrumental delivery (adjusted OR 2.97; 95% CI: 1.16-8.23).Conclusions: Obesity adds more risk to postdate women undergoing induction of labor. Obesity increases the incidence of CD and failed induction among induced postdate women. Therefore, obstetricians should encourage obese women to reduce weight before getting pregnant, and to comply with the optimal weight gain during pregnancy in attempt to reduce the rates of postdating, CD and failed induction

MAT-708: MONITORING THE CORROSION PROCESS OF REINFORCED CONCRETE FLAT SLAB-COLUMN CONNECTION

The corrosion of the steel reinforcement embedded in a two-way reinforced concrete flat slab around the column stub area was investigated in this study, which aimed to studying the effect of corrosion on the shear punching behavior. Two square flat slab-column connections were cast, the flat slab dimension was 1900 mm × 1900 mm × 150 mm, and the column dimensions was 250 mm × 250 mm. A specific delaminated area was corroded around the column stub to emphasize the effect of corrosion around punching area. The corrosion reached two levels of mass loss uniformly over that specified area: 0% and 26%. Corrosion process was monitored under an accelerated corrosion technique through the application of a constant potential of fifteen volts to reach the targeted uniform corrosion level. Then, the corrode slab-column connection was loaded until failure for each slab occurred. The corrosion performance of the slab was evaluated based on the results of the current measurement, half-cell potential tests, and mass loss. The test results show that the corrosion of reinforcement rebar around the column stub in flat slab causes a significant loss in punching shear capacity and affects the structural integrity by increasing crack widths

Statistical optimization as a powerful tool for indole acetic acid production by Fusarium oxysporum

Crop production is challenged in our world by increasing food demands, decrease natural resource bases and climatic change. Nowadays plant growth regulators works like fertilizers in increasing plant growth production efficiency and needed to produce in large industrial scale. Fermentation condition and medium constituents can significantly affect on the product production and designing an acceptable fermentation medium is critical importance. In this paper Fusarium sp. could be considered as promising indole-3-acetic acid producers with the ability to improve the production using statistical methods. The results showed that fermentation type, incubation temperature and L-tryptophan were the most influencing parameters on the production. Maximum IAA production by Fusarium oxysporum was 300.4 mg/l obtained under the fermentation conditions: temperature at 25oC, incubation period 5 days, pH 7, inoculums size 2%, shaking rate at 150 rpm and medium constituents: Glucose 40 g/l, yeast extract 3 g/l, L-tryptophan 1 g/l, KH2PO4 2 g/l, NaNO3 4 g/l, MgSO4·7H2O 0.1 g/l with regression analysis (R2) 99.67% and 2.12-fold increase in comparison to the production of the original level (142 mg/l). DOI: http://dx.doi.org/10.5281/zenodo.101234