Impact of Holes on the Buckling of RHS Steel Column

في هذا البحث تم اجراء دراسة عملية ونظرية لتأثير الفتحات في تصرف الاعمدة الفولاذية المستطيلة المجوفة المعرضة لأحمال ضغط محورية. تم فحص عينات لدراسة التحمل الاقصى وتصرف حمل-أزاحات محورية للأعمدة الفولاذية. في هذا البحث تم استخدام نظرية العناصر المحددة المتمثلة ببرنامج ANSYS 12.0 لتحليل تصرف الاعمدة المستطيلة المجوفة مع فتحات. في الجزء العملي استعملت اربعة وعشرون نموذج من الاعمدة الفولاذية المستطيلة المجوفة بزوايا مدورة الذي له ابعاد مقطع 50*80)) ملم وارتفاع 250,500)) ملم و بسمك (1.25,4 and 6) ملم مع ابعاد حفرة ((80*α)*80) ملم بحيث ان α مساوية الى 0.2,0.4,0.6 and 0.8)) . تم فحص اربعة وعشرون من الاعمدة الفولاذية تحت حمل انضغاط من اجل التحقيق في تأثير الحفرة في المقاومة القصوى للأعمدة المستطيلة المجوفة. أظهرت النتائج العملية أن طريقة الفشل النموذجية لجميع العينات المجوفة المختبرة كانت التواء المحلي. وأظهرت النتائج التي تم اختبارها أن زيادة ابعاد الحفرة يؤدي إلى الحد من الحمل الاقصى للعمود يصل إلى 75%. وأظهرت النتائج تقليل الحمل بنسبة  94.7%بسبب انخفاض سمك العمود بينما يكون حجم الثقب ثابتا. ينخفض ​​الحمل التواء بنسبة  84.62%عندما يتغير موفع الحفرة  من 0.25L إلى 0.75L. يمكن إجراء الحفرة في منتصف العمود مع بعد يصل إلى 0.4 من طول العمود. و AISC(2005) يعرض القيم الأقرب إلى النتائج العملية  لمقاومة خضوع الانضغاط. أدى تأثير زيادة نسبة الانحناء ونسبة السمك إلى مساحة (t / A) مما أدى إلى خفض مقومة الانضغاط الحرجة وفشل العمود مع حجم كبير من الحفرة و (t / A) نسبة أقل من  0.74%ويرجع ذلك إلى الانبعاج المحلي في حين أن فشل الإبزيم العالمي كان معتمدا للعمود مع حجم صغير من الحفرة و (t / A) نسبة فوق 0.74%. وأظهرت النتائج وجود اتفاق معقول بين النتائج العملية والنظرية وكان الفرق يتراوح بين(1.28-14.88)%.This study presented an experimental and theoretical study on the effect of hole on the behavior of rectangular hollow steel columns subjected to axial compression load. Specimens were tested to investigated the ultimate capacity and the load- axial displacement behavior of steel columns. In this paper finite element analysis is done by using general purpose ANSYS 12.0 to investigate the behavior of rectangular hollow steel column with hole. In the experimental work, rectangular hollow steel columns with rounded corners were used in the constriction of the specimens which have dimensions of cross section (50*80)mm and height of (250 and 500)mm with thickness of (1.25,4 and 6)mm with hole ((α*80)*80)mm when α is equal to (0.2,0.4,0.6 and 0.8). Twenty four columns under compression load were tested in order to investigate the effect of hole on the ultimate load of rectangular hollow steel column. The experimental results indicated that the typical failure  mode for all the tested hollow specimen was the local buckling. The tested results indicated that the increasing of hole dimension leads to reduction in ultimate loads of tested column to 75%. The results show the reducing of load by 94.7% due to decreasing  the thickness of  column while the hole size is constant (0.2*80*80). The buckling load decreases by 84.62% when hole position changes from Lo=0.25L to 0.75L. Holes can be made in the middle of column with dimension up to 0.4 of column's length. The AISC (2005) presents the values closest to the experimental results for the nominal yielding compressive strength. The effect for increasing of slendeness ratio and thickness to area ratio(t/A) leading to decreacing the critical stresses and the failure of column with large size of hole and (t/A) ratio less than 0.74% was due to lacal  buckling while the global buckling failure was abserve for column with small size of hole and (t/A) ratio above than 0.74%. The compersion  between the experimental and theoretical results showed a reasonable agreement and the difference was in the range (1.28-14.88)%.     &nbsp

Non-Linear Buckling Analysis of Non-Prismatic Steel Columns Subjected to Axial Compression Loads

This study investigates the effect of non-uniform cross-section on the behavior of steel columns subjected to axial compression load. A nonlinear finite element model using ANSYS 12.0 has been adopted to investigate the behavior of square and circular steel columns. The steel is assumed to behave as an elastic-plastic material with strain hardening in compression. The type of elements have been used to model the steel; SOLID45. The axial- load displacement curves and the deformation shapes were predicted. A parametric study on columns with square and circular section has been done. All the analyzed columns have the same value of cross-section volume for the column, yielding strength, and boundary conditions with different length of column. The results show that the behavior of non-prismatic column is always by the tapering ratio and the slenderness ratio on the elastic buckling. As the taper ratio increases, the elastic buckling load increases, in the main while the maximum ultimate load occurs in the (prismatic column) comparing with the non-prismatic column. Keywords: Non-uniform cross-section, Steel columns, nonlinear finite element, Elastic buckling load

Optimal Multiprocessor Locking Protocols Under FIFO Scheduling

Real-time locking protocols are typically designed to reduce any priority-inversion blocking (pi-blocking) a task may incur while waiting to access a shared resource. For the multiprocessor case, a number of such protocols have been developed that ensure asymptotically optimal pi-blocking bounds under job-level fixed-priority scheduling. Unfortunately, no optimal multiprocessor real-time locking protocols are known that ensure tight pi-blocking bounds under any scheduler. This paper presents the first such protocols. Specifically, protocols are presented for mutual exclusion, reader-writer synchronization, and k-exclusion that are optimal under first-in-first-out (FIFO) scheduling when schedulability analysis treats suspension times as computation. Experiments are presented that demonstrate the effectiveness of these protocols

Tight Tardiness Bounds for Pseudo-Harmonic Tasks Under Global-EDF-Like Schedulers

The global earliest-deadline-first (GEDF) scheduler and its variants are soft-real-time (SRT) optimal for periodic/sporadic tasks, meaning they provide bounded tardiness so long as the underlying platform is not over-utilized. Although their SRT-optimality has long been known, tight tardiness bounds for these schedulers have remained elusive. In this paper, a tardiness bound, that does not depend on the processor or task count, is derived for pseudo-harmonic periodic tasks, which are commonly used in practice, under global-EDF-like (GEL) schedulers. This class of schedulers includes both GEDF and first-in-first-out (FIFO). This bound is shown to be generally tight via an example. Furthermore, it is shown that exact tardiness bounds for GEL-scheduled pseudo-harmonic periodic tasks can be computed in pseudo-polynomial time

Location of voltage sag source by using artificial neural network

Power quality (PQ) is a major concern for number of electrical equipment such as sophisticated electronics equipment, high efficiency variable speed drive (VSD) and power electronic controller. The most common power quality event is the voltage sag. The objective is to estimate the location of voltage sag source using ANN. In this paper, the multi-monitor based method is used. Based on the simulation results, the voltage deviation (VD) index of voltage sag is calculated and assigned as a training data for ANN. The Radial Basis Function Network (RBFN) is used due to its superior performances (lower training time and errors). The three types of performance analysis considered are coefficient of determination (R2), root mean square error (RMSE) and sum of square error (SSE). The RBFN is developed by using MATLAB software. The proposed method is tested on the CIVANLAR distribution test system and the Permas Jaya distribution network. The voltage sags are simulated using Power World software which is a common simulation tool for power system analysis. The asymmetrical fault namely line to ground (LG) fault, double line to ground (LLG) fault and line to line (LL) fault are applied in the simulation. Based on the simulation results of voltage sag analysis, the highest VD is contributed by LLG for both test systems. Based on the proposed RBFN results, the best performance analysis are R2, RMSE and SSE of 0.9999, 5.24E-04 and 3.90E-05, respectively. Based on the results, the highest VD shows the location of voltage sag source in that system. The proposed RBFN accurately identifies the location of voltage sag source for both test systems

SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL STUDY OF MANNICH BASES AND THEIR COPPER (II) COMPLEXES

Objective: The present study is focused on the synthesis of novel Mannich bases and their metal complexes, and to characterize them by physical, chemical and biological methods. Mannich bases, 2-(piperazin-1-yl(thiophen-2-yl)methyl)hydrazinecarboxamide (PTMHC), 2-(piperazin-1-yl(thiophen-2-yl)methyl)hydrazinecarbothioamide (PTMHCT), and 2-((4-methylpiperazin-1-yl)(thiophen-2-yl)methyl)hydrazinecarboxamide (MPTMHC) and 2-((4-methylpiperazin-1-yl)(thiophen-2-yl)methyl)hydrazinecarbothioamide (MPTMHCT), were prepared by Mannich condensation method.Methods: The compounds and complexes were prepared by known literature methods. Characterizations were carried out through physical methods such as elemental analyses, melting point and TLC. IR, 1H NMR, [13]C NMR and Mass spectral studies were carried out to characterize the ligands. The methods like EPR, magnetic susceptibility measurements, conductance measurements and thermal analysis were carried out for complexes besides the UV-Vis and IR spectral studies. Anti-cancer activity of synthesized ligands was performed using human lung and colon cancer cell lines.Results: Eight compounds have been prepared and characterized. Four among the eight compounds were used as ligands for the preparation of metal complexes. The results of physical and chemical methods show all the complexes act as bidentate ligands. The coordination with the metal ion takes place through N, S and O atoms. The results of molar conductivity and magnetic susceptibility measurements reveal the electrolytic and non-electrolytic nature of the metal complexes. EPR and TG-DTA studies also support the other spectral data.Conclusions: Copper (II) complexes of PTMHC, PTMHCT, MPTMHC, and MPTMHCT were prepared and their structures were determined. The anti-cancer activity of the synthesized ligands and their complexes was evaluated. The synthesized novel ligands of Mannich bases can serve as a potential anti-cancer agent.Â

Application of ANN to Real and Reactive Power Allocation Scheme

This chapter describes the implementation of ANN for real and reactive power transfer allocation. The 25 bus equivalent power system of south Malaysia region and IEEE 118 bus system are used to demonstrate the applicability of the ANN output compared to that of the Modified Nodal Equations (MNE) which is used as trainers for real and reactive power allocation. The basic idea is to use supervised learning paradigm to train the ANN. Then the descriptions of inputs and outputs of the training data for the ANN are easily obtained from the load flow results and each method used as teachers respectively. The proposed ANN based method provides promising results in terms of accuracy and computation time. Artificial intelligence has been proven to be able to solve complex processes in deregulated power system such as loss allocation. So, it can be expected that the developed methodology will further contribute in improving the computation time of transmission usage allocation for deregulated system

Seed quality and germination in selected hybrids of oil palm (Elaeis guineensis, Jacq.)

Different indigenous oil palm hybrids were evaluated with an objective to assess their quality and to develop seed quality standards in commercial seed production centers. Majority of the indigenous hybrids had large proportion of small seeds and their percentage of distribution varied according to the hybrids. The different hybrid combinations recorded coefficient of variation of 11.70, 11.28 and 15.35 for seed weight, shell weight and kernel weight, respectively. Large seed group in all the crosses had high seed weight, shell weight, shell thickness and kernel weight. Though shell thickness had significant differences among crosses and size groups, the coefficient of variation recorded (6.38%) was low compared to other characteristics. Selected hybrids had low average kernel weight of 1.63, 1.05 and 0.74 g for large, medium and small seeds, respectively. In this study, high and low germination percentage was recorded in all the categories of seed groups irrespective of their sizes. All the seed physical parameters studied were positively correlated which are highly significant

Detection of streptomycin residues in local meat of bovine and ovine

From meat retails in Mosul province, forty-five meat samples of local ovine and bovine (23 bovine samples and 22 ovine samples) were collected. The period of collection was during November 2010 to May 2011, by means of multistage random sampling for detection of streptomycin residues. Enzyme linked immunosorbent assay (ELISA) was used for detection of streptomycin residues. The results revealed that eleven ovine meat samples (50%) were positive to streptomycin residue, with a mean value 35.06 µg kg-1, while 14 bovine meat samples (60.86%) were positive to residual streptomycin with a mean value 59.56 µg kg-1. From the results, it is clear that all tested meat samples (ovine and bovine) were safe enough for human consumption

Torsional behavior of reinforced recycled aggregate flowing concrete hollow section beams

Fifteen reinforced concrete beams made with recycled aggregates and flowing concrete, which were tested under pure torsion to study the torsional behavior. The major parameters in this study were the percent of the recycled aggregates and the number of transverse reinforcements. The torsional response and crack behavior were investigated in this study. From the results, it can be noted that the increase of the recycled aggregate led to a decrease in the critical and ultimate torque of the beam, also, the increasing the number of transverse reinforcements led to the enhancement of the critical and ultimate torque. Numerical analysis by finite element method was conducted and gave a good indicator for agreement in the results of critical and ultimate load between the numerical and experimental study, as well as the angle of twisting of the beam. The second approach was Hsu᾽s softened truss model, the model proves it can predict the critical and ultimate torque for the beam and showed its ability to describe the behavior of the beams before and after cracks