Study and Solution of Current Differential Protection Disability for High Series Compensation Transmission Line

With the increasing day by day integration of large-size generators and tighter among the power systems, in internal fault, the fault current of Series Compensated (SC) lines could also be upturned. Therefore, the differential protection of SC transmission lines may stop working to operate because of less sensitivity. In this research article the causes for the current overturning in SC lines and its effects differential protection. The working characteristics of differential protection are analyzed by focusing on multiple-factors, for example, different series compensation degrees, types of fault, system operation mode, the difference of power angle, points of the fault, and transition resistance. An enhanced standard based on the current amplitudes and phases on both sides of the series compensated lines is proposed. Furthermore, to make stronger the operation characteristics of differential protection, the triple-fold line is chosen to get better sensitivity for internal faults in the article. The results are efficient to improve the protection sensitivity of SC lines during the internal fault. The PSCAD/EMTDC simulation and the power system dynamic physics simulation demonstrate that protection sensitivity is increased in the improved scheme. Keywords: Differential Protection, Series compensation, EHV/ UHV, Current reverse, sensitivity analysis. DOI: 10.7176/CTI/10-06 Publication date: August 31st 202

Assessment Resistance Potential to Moisture Damage and Rutting for HMA Mixtures Reinforced by Steel Fibers

Rutting is mainly referring to pavement permanent deformation, it is a major problem for flexible pavement and it is a complicated process and highly observed along with many segments of asphalt pavement in Iraq. The occurrence of this defect is related to several variables such as elevated temperatures and high wheel loads. Studying effective methods to reduce rutting distress is of great significance for providing a safe and along-life road. The asphalt mixture used to be modified by adding different types of additives. The addition of additives typically excesses stiffness, improves temperature susceptibility, and reduces moisture sensitivity. For this work, steel fibres have been used for modifying asphalt mixture as they incorporated in the specimens by three percentages designated as 0.5, 1.0 and 1.5 % by the weight of asphalt mixture. The evaluation process based on conducting Marshall Test, Compressive strength test, and the wheel tracking test. The optimum asphalt content was determined for asphalt mixture. The results of the Marshall quotient and the index of retained strength of modified mixtures were increased by 44.0 and 17.38% respectively with adding 1.0% of steel fibres compared with the conventional mixture. The rut depth and dynamic stability were determined by using a wheel tracking test at two various testing temperatures of 45 and 55°C and two applied stresses of 70 and 80 psi. Results show that adding 1% of steel fibres to asphalt mixtures is very effective in increase the rutting resistance and reduce moisture damage

Complex Fractional-Order LQIR for Inverted-Pendulum-Type Robotic Mechanisms: Design and Experimental Validation

This article presents a systematic approach to formulate and experimentally validate a novel Complex Fractional Order (CFO) Linear Quadratic Integral Regulator (LQIR) design to enhance the robustness of inverted-pendulum-type robotic mechanisms against bounded exogenous disturbances. The CFO controllers, an enhanced variant of the conventional fractional-order controllers, are realised by assigning pre-calibrated complex numbers to the order of the integral and differential operators in the control law. This arrangement significantly improves the structural flexibility of the control law, and hence, subsequently strengthens its robustness against the parametric uncertainties and nonlinear disturbances encountered by the aforementioned under-actuated system. The proposed control procedure uses the ubiquitous LQIR as the baseline controller that is augmented with CFO differential and integral operators. The fractional complex orders in LQIR are calibrated offline by minimising an objective function that aims at attenuating the position-regulation error while economising the control activity. The effectiveness of the CFO-LQIR is benchmarked against its integer and fractional-order counterparts. The ability of each controller to mitigate the disturbances in inverted-pendulum-type robotic systems is rigorously tested by conducting real-time experiments on Quanser single-link rotary pendulum system. The experimental outcomes validate the superior disturbance rejection capability of the CFO-LQIR by yielding rapid transits and strong damping against disturbances while preserving the control input economy and closed-loop stability of the system

Effect of Pulse Shapes on the Weldability of High Conductivity Copper ‎C101 by Nd-YAG Laser

تم لحام وصلات تراكب مماثلة من صفائح رقيقة من النحاس النقي C101 باستخدام اللحام بالليزر النبضي. تم دراسة تأثير معاملات اللحام بالليزر على الخواص الميكانيكية. أظهرت النتائج التجريبية أنه يمكن الحصول على وصلات خالية من عيوب الصوت من وصلات نحاسية - نحاسية مماثلة حيث يحدث الكسر بعيدًا عن خط اللحام. يقترح العمل الحالي تحسين التحكم في التصميم لثلاثة أشكال مختلفة للنبض؛ مستطيلة (عادية)، منحدرة لأسفل ومعدلة وتستخدم في لحام ست عينات نحاسية مختلفة لتحقيق أقصى قوة شد وقص للمفاصل. أوضحت النتائج أن شكل النبضة المعدلة هو الأمثل في اختبار شد القص. كان لشكل النبضة المنحدرة تأثير أقل أهمية على قوة المفصل النحاسي عند مقارنته بشكل النبضة المستطيلة. تم الحصول على العلاقة بين معلمات الإدخال والإخراج من خلال استخدام برنامج Minitab، وتم استخدام برنامج Matlab للوصول إلى الحل الأمثل. أظهرت الخوارزمية الجينية أن المقدار الأمثل الذي تم تحقيقه لقوة القص كان 77.9 ميجا باسكال، وكانت معلمات الإدخال المثلى هي طاقة النبضة البالغة 39 جول وعرض النبضة 8.5 وتردد 10 هرتز والسرعة الخطية 160 ملم / دقيقة. Similar lap joints of pure copper C101 thin sheets were welded using pulsed laser welding. The effect of laser welding parameters on mechanical properties was investigated. The experimental results revealed that sound defect-free joints could be obtained from similar copper-copper joints where the fracture occurs away from the weld line. The present work proposes improved design control for three different pulse shapes; rectangular (normal), ramped-down and modulated which are used to weld six different copper samples to achieve the optimum tensile-shear strength of the joints. Results showed that modulated pulse shape has the optimum in the shear-tensile test. Ramped-down pulse shape had a less significant effect on the strength of the copper joint when compared with the rectangular pulse shape.  The relationship between the input and output parameters was obtained by employing Minitab software, and the Matlab software was used in order to reach the optimum solution. The genetic algorithm showed that the optimum magnitude achieved for the shear strength was 77.9 MPa, and the optimum input parameters were pulse energy of 39J, the pulse width of 8.5, frequency of 10Hz and linear speed of 160mm/min.&nbsp

Use of N-acetylcysteine in children with fulminant hepatic failure caused by acute viral hepatitis

Objective: To determine the efficacy of N-acetylcysteine (NAC) in children aged \u3e 1 month to 16 years admitted with Fulminant Hepatic Failure (FHF) secondary to Acute Viral Hepatitis (AVH) in a tertiary care center of a developing country. Study Design: Analytical study. Place and Duration of Study: Department of Paediatrics, The Aga Khan University Hospital, Karachi, Pakistan, from January 2007 to December 2011. Methodology: Medical records of children (\u3e 1 month - 16 years) with FHF admitted with AVH of known etiology who received NAC were reviewed retrospectively. Liver function tests (mean ± SD) at baseline, 24 hours after NAC and before or at the time of discharge/death were recorded and compared via using repeated measures ANOVA (r-ANOVA). Efficacy of NAC is defined in improvement in biochemical markers, liver function test and discharge disposition (survived or died). Mortality associated risk factors were identified by using logistic regression analysis. P-value and 95% confidence interval were recorded. Results: Forty children (mean age was 80 ± 40 months) with FHF secondary to AVH received NAC. Majority were males (n=25; 63%). Vomiting (75%) and jaundice (65%) were the main presenting symptoms, one-third had hypoglycemic, while 40% had altered sensorium at the time of admission. There was significant statistical difference in liver enzymes and prothrombin time on admission comparing at discharge in children received NAC (p \u3c 0.001). Fifteen (38%) children died. Severe vomiting {Odds Ratio (OR) 0.22, 95% Confidence Interval (CI) 0.05 - 0.8}, jaundice (OR 9.3, CI 1.1 - 82.6), inotropic support (OR 20.6, CI 3.5 - 118.3) and mechanical ventilation (OR 4.3, CI 1.1 - 16.6) at the time of admission are associated with risk factors for mortality in children with FHF secondary to AVH. Conclusion: NAC used in children with FHF secondary to AVH is associated with markedly improved liver function tests and recovery. FHF with complications is high risk for mortalit

Finite Element Analysis and Optimization of Steel Girders with External Prestressing

Optimization is a process through which the best possible values of design variables are achieved under the given of constraints and in accordance to a selected optimization objective function. Steel I-girders have been used widely in different fields, which are generally fabricated by connecting two plate flanges, a flat web and a series of longitudinal or transverse stiffeners together. The use of steel girder with external prestressing has been used in many countries as a means of strengthening bridges. The purpose of this paper is to develop a finite element model for the optimization of a steel girder with external prestressing. The ANSYS finite element software package was used to find the optimum cross section dimension for the steel girder. Two objective functions are considered in this study there are optimization of the strain energy and total volume of the girder. The design variables are the width of top flange, the thickness of top flange, the width of bottom flange, the thickness of bottom flange, the height of the web, the width of the web and area of prestressing tendons. Two type of steel girder are considered there are steel girder without prestressing and steel girder with prestressing. The results for volume minimization shows that the optimum cross section for steel girder with prestressing smaller than for steel girder without prestressing

ENTREPRENEURIAL MARKETING, ENVIRONMENTAL UNCERTAINTY AND PERFORMANCE OF FAMILY FIRMS

Businesses in general and family SMEs in specific are vulnerable to environmental uncertainty in underdeveloped countries. Stiff competitions, technological bursts and market turbulence appears as a catastrophe and a major cause for short life of many family SMEs. A few family SMEs still exist and survive in all these uncertain conditions. Various reasons been discussed in previous literature and had proved the importance of entrepreneurial marketing as one of the major sources of high performances. The marketing strategies opted by family SMEs having dimension of entrepreneurship, are not only self-beneficial but also the cause of new market trends. The primary purpose of this study is to consider the effect of opportunity vigilance, consumer centric innovation, value creation and risk management termed as entrepreneurial marketing and used as a fundamental approach for family SMEs to survive and grab high performances even under uncertain conditions. Results show that entrepreneurial marketing in family SMEs is positively associated with high performances even under uncertain environments. Previously uncertain environments were considered as one of the major cause for entrepreneurial marketing that does not qualify in our case. Family SMEs use entrepreneurial marketing as their vital tool for competitive markets to perform high irrespective of environmental conditions i.e. either favorable or unfavorable.Â

Vibration Analysis of Uniform and Tapered Composite Beams with Embedded Shape Memory Alloy

في هذا البحث تم تهجين مواد مركبة باستخدام اسلاك النتنول (نيكل-تيتانيوم). تم تصنيع العينات بتقنية القولبة اليدوية، وتم استخدام راتنج الايبوكسي نوع (Sikadur 52 N) وطبقة من ليف الزجاج ذات الحصيرة المنتظمة، وتم استخدام اسلاك النتنول لتدعيم العينات وبقطر (٠.٥ملم) وبعدد (٠،١،٣ ،٥ و٩) سلك لايجاد تاثير عدد الاسلاك على التردد الطبيعي. العينات تكون على شكل عتبة كابولية مثبتة من طرف وحرة من الطرف الاخر. تمت دراسة تاثير زيادة كل من عدد اسلاك النتنول وقطراسلاك النتنول وطول وسمك العتبة الكابولية على الترددات الطبيعية للعتبة. وكذلك تمت دراسة تاثير ميلان عرض وسمك العتبة الكابولية على التردد الطبيعي. وضحت النتائج زيادة كل من عدد اسلاك النتنول وقطر اسلاك النتنول يؤديان لتقليل التردد الطبيعي في طور المارتنسايت ويؤديان الى زيادة التردد الطبيعي في طور الاوستنايت. كذلك اوضحت النتائج ان زيادة سمك العينة وزيادة نسبة العرض العرض يؤدي الى زيادة التردد الطبيعي. وكذلك زيادة نسبة السمك للعينة يؤدي الى زيادة التردد الطبيعي الاول وتقليل التردد الطبيعي الثاني والثالث. وكذلك زيادة طول العينة يقلل من التردد الطبيعي.In this study, laminated composite materials were hybridized with E-glass fiber and Nitinol (Nickel-Titanium) wires. Hand lay-up technique was used to prepare the samples, epoxy resin type (Sikadur 52 N) was used as matrix reinforced by one fiber from E-glass fiber woven roving with embedded nitinol wires with a diameter 0.5 mm for samples and number of wires such as 0, 1, 3, 5 and 9 to find the effect of the number of wires on the natural frequency. The samples were fixed as a cantilever beam. The effects of increasing the number of nitinol wires, the diameter of nitinol wires, the length of the cantilever beam and the thickness of beam on the natural frequencies of the beam were studied. Also, the effects of the tapered in width side and thickness side on the natural frequencies of cantilever beam were studied. The results showed that the increasing in the number of nitinol wires and the diameter of nitinol wires lead to decrease the natural frequency in martensite phase and increase the natural frequency in austenite phase. Also, the increasing in thickness of beam and width ratio of the beam lead to increase the natural frequency. As well as, the increasing in the thickness ratio leads to increase the first natural frequency and decrease the second and third ones. In addition, the increasing in the length of the beam decreases the natural frequency