The poet ‘Umāra al-Yamanl

Abū Muḥammad ‘Umarā ibn ‘Alī was born in the Yemen in 515/1121. He studied jurisprudence at Zabid (531-535 A.H.) then he taught Shāfi ‘ī Jurisprudence there. While on pilgrimage to Mecca in 538/1145 he met the Queen al-Ḥurra of Zabid and became one of her close friends. He began trading between Aden and Zabid in 538 A.H., and became rich, famous, and a friend of Ibn Saba’ (the Dā’ī of Aden), his Vizier Bilāl b. Jarīr and his secretary al-‘Abdī. He was sent by the Prince of “al-Haramain” (Qāsim b. Hāshim b. Falita), on a mission to the Fatimid Caliph (al-Fā’iz) in Egypt in 549 A.H. So successful was his mission that the Prince of al-Ḥaramain sent him on another mission in 551 A.H. He went to Egypt and settled there, living happily until Saladin ended the Fatimid Callphate in 567 A.H. when ‘Umāra was involved in a plot to replace the son of the last Fatimid Caliph on the throne. The plot was betrayed and ‘Umāra was executed on 2 Ramaḍān 569/6 April 1175) (Chapter 1 Part I P. 28-78). 2. ‘Umāra had a good character, so that most people liked and respected him. He was a faithful and pious Moslim, so that he seemed proud of his religion. He belonged to Shāfi’ī sect by birth, education and in his way of thinking; so it was said that he was a fanatic of sunna,. He was one of the most learned of the people of his time. He studied jurisprudence, Tafsīr, Hadith, Ḥistory, Arabic literature and language. Then he wrote many books in addition to his “Dīwān”: al-Nukat al-‘Aşriyya, Tārikh al-Yaman, Shu‘arā’ al-Yaman, al-Farā’iḍ and Sīrat al-Sayyida Nafīsa. All this made him gain a good position in society (Chapter 2 P. 77-129). 3. ‘Umāra’s poetic talent was revealed in Adon by the help of al-‘Abdī, grew at Zabid, and his fame made complete in Egypt especially when he joined “Dīwān al-Shu’arā’” in the Fatimid Caliphate. So he became one of the greatest poets of his time until Saladin’s reign when he become neglected. (Chapter 1 Part II P. 131-159). 4. ‘Umāra was a panegyrist. He was expert in eulogy in which was most of his poetry, but he also wrote in most of the poetical themes common to this time; elegy opistolary-poetry, satire, love poetry, ascetic-poetry, descriptive-poetry and other themes. (Chapter 2 P. 160-230). 5. ‘Umāra constantly sought to express his ideas lucidly, so most of his poetry was understood by ordinary readers. Although his style was not distinguished, it was adequate, and his language was eloquent. He was fond of rhetorical figures (Badī’) which can be seen in most of his poetry. While he avoided strange rhymes and rare metres he wrote many "Urjāzas" and "Muwashshaḥs". (Chapter 3. P. 23I - 282). 6. ‘Umāra made use of some of his predecessors’ art, especially Abū Tammām, al-Buḥturi and al-Mutanabbī. Similarly some of his followers benefitted from his art. His poetic thought and descriptions reached a high level, and he won the admiration of Arabs everywhere. His importance, then, was as a poet who was able to recording his poetry the events which happened in his time, and he was one of the pioneers of "Muwashshaḥs" in the east. (Chapter 4. P. 283 - 318)

Polynomial Differential Equations with Small coefficients

Classes of polynomial differential equations of degree n are considered. An explicit upper bound on the size of the coefficients are given which implies that each equation in the class has exactly n complex periodic solutions. In most of the classes the upper bound can be improved when we consider real periodic solutions. We present a proof to a recent conjecture on the number of periodic solutions. The results are used to give upper bounds for the number of limit cycles of polynomial two-dimensional systems.Comment: 15 page

The Fire Exposure Effect on Hybrid Reinforced Reactive Powder Concrete Columns

This paper offers an experimental investigation of the fiber reinforced reactive powder concrete columns' behavior after exposure to fire and improvements made to improve column resistance against fire. This study is mainly aimed to study the experimental behavior of hybrid reinforced columns produced by reactive concrete powder (RPC) and exposure to the flame of fire at one side and subjected to eccentric load. The experimental methodology consists of sixteen RC columns that organized into four groups based on the variables used in this research: (SF) steel fibers, (PP) polypropylene fibers, (HB) hybrid fibers, (PPC-SF) hybrid cross-section (steel fiber reactive powder concrete core with polypropylene fiber reactive powder concrete cover). All columns were tested under 60 mm eccentric load and the burn columns were exposed to fire for different duration (1, 1.5 and 2) hours. The results indicated that (SF-RPC, PP-RPC, HB-RPC, PPC-SFRPC) columns exposed to a fire flame for the period 2 hours, lost from their load capacity by about (54.39, 40.03, 34.69 and 30.68) % respectively. The main conclusion of this paper is that the best fire resistance of the column obtained when using a hybrid cross-section (steel fiber reactive powder concrete core with polypropylene fiber reactive powder concrete cover)

Behavior of One – Way Concrete Slabs with Edge Beams Reinforced/Strengthened by CFRP Rods under Uniformly Distributed Load

This research presents an experimental investigation on the flexural behavior of eight one-way concrete slabs with edge beams under uniformly distributed load. The models are reinforced or strengthened using CFRP rods and two control models reinforced by deformed steel bars.The dimensions of one-way slab is 1.05 m width, 1.25 m length and 0.1 m thick., while each edge beam is of length 1.25m and depth 0.2m by width 0.1m. Different reinforcement ratios were used. The models were tested under universal testing machine and supported at corners on four stiff steel columns. The models were tested up to failure to study their flexural behavior including load-deflection curves, crack patterns and mode of failure. Among the conclusions obtained, the models reinforced by CFRP rods can attain flexural strength higher than those reinforced by deformed steel bars of same amount. This increase is about (38-44%)

Effects of Steel Fibers Geometry on the Mechanical Properties of SIFCON Concrete

This research aims to shed light on the effect of steel fiber shape, length, diameter, and aspect ratio on the mechanical properties of slurry infiltration fiber reinforced concrete (SIFCON). This study comprised of casting and testing three groups of SIFCON specimens with 6% fiber volume fraction. The first group was reinforced with micro steel fiber, other reinforced by hook end steel fibers, while the last group of specimens reinforced by mixing two shape of steel fiber as hybrid fiber (3% micro steel fiber +3% hook end steel fiber). Silica fume was used as a partial replacement (10%) by weight of cement. 3.7% super plasticizer was used to make the slurry liquid enough to penetrate through the fiber network, while the w/c ratio kept constant at 0.33. It was found from the results achieved that the compressive strength, static modulus of elasticity, splitting tensile strength and toughness are extremely affected by the geometry of fibers because the network of fibers formed and their density depends on the size and shape of fibers. Where the values of micro steel fibers are far outweighing the values of hooked end fibers. It was also deduced from empiricism results that combining long and short fibers gives excellent results

Limitations on ACI Code Minimum Thickness Requirements for Flat Slab

Reinforced concrete two-way flat slabs are considered one of the most used systems in the construction of commercial buildings due to the ease of construction and suitability for electrical and mechanical paths. Long-term deflection is an essential parameter in controlling the behavior of this slab system, especially with long spans. Therefore, this study is devoted to investigating the validation of the ACI 318-19 Code long-term deflection limitations of a wide range of span lengths of two-way flat slabs with and without drop panels. The first part of the study includes nonlinear finite element analysis of 63 flat slabs without drops and 63 flat slabs with drops using the SAFE commercial software. The investigated parameters consist of the span length (4, 5, 6, 7, 8, 9, and 10m), compressive strength of concrete (21, 35, and 49 MPa), the magnitude of live load (1.5, 3, and 4.5 kN/m2), and the drop thickness (0.25tslab, 0.5tslab, and 0.75tslab). In addition, the maximum crack width at the top and bottom are determined and compared with the limitations of the ACI 224R-08. The second part of this research proposes modifications to the minimum slab thickness that satisfy the permissible deflection. It was found, for flat slabs without drops, the increase in concrete compressive strength from 21MPa to 49MPa decreases the average long-term deflection by (56, 53, 50, 44, 39, 33 and 31%) for spans (4, 5, 6, 7, 8, 9, and 10 m) respectively. In flat slab with drop panel, it was found that varying drop panel thickness t2 from 0.25  to 0.75  decreases the average long-term deflection by (45, 41, 39, 35, 31, 28 and 25%) for span lengths (4, 5, 6, 7, 8, 9 and 10 m) respectively. Limitations of the minimum thickness of flat slab were proposed to vary from Ln/30 to Ln/19.9 for a flat slab without a drop panel and from Ln/33 to Ln/21.2 for a flat slab with drop panel. These limitations demonstrated high consistency with the results of Scanlon and Lee's unified equation for determining the minimum thickness of slab with and without drop panels. Doi: 10.28991/cej-2021-03091769 Full Text: PD

PERFORMANCE EVALUATION OF SEED DRILL- FERTILIZER UNDER TWO DIFFERENT FARMING SYSTEMS AND TRACTOR PRACTICAL SPEEDS

This study was aim to investigate performance of seed drill - fertilizer (GIL-SAX multisem18) was evaluated under two different farming systems (till and no-till) and tractor speeds (5.28, 7.76 and 8.30 km.h-1). The characteristics were measured including draft force, wheel slip, seed delivery rate, and germination rate. The experiment was organized as a randomized complete block design (RCBD). The significant difference was examined using the least significant difference tests at a P≤0.05. The results showed a minimum draft force and wheel slip under the till system and tractor speed of 5.28 km.h-1 interaction. The lowest seed delivery rate was found when no-till was practiced with a speed of 5.28 km.h-1. Adopting the no-till system with the speed of 7.76 km.h-1 achieved the highest germination rate. The till system achieved the lowest fuel cost in economic analysis 8395 IQD. ha-1 at a speed of 8.30 km.h-1, while the no-till system achieved the lowest cost of seeds 65066 IQD. ha-1 and sowing operation cost 36079 IQD. ha-1 at speed 5.28 km.h-1. Irrigation and agronomy indicators should be addressed in the further work. 

Experimental Study on the Behavior of Axially Loaded Reinforced Concrete Square Columns Strengthened with SIFCON Shell

Slurry infiltrated fiber concrete (SIFCON) is an advanced generation of fiber-reinforced concrete (FRC) with higher fiber content. SIFCON offers excellent potential for use in areas that require high ductility and impact resistance, particularly when designing seismic retrofits and repairing or strengthening structural reinforced concrete members. This study investigated the behavior of square normal strength concrete (NSC) columns of grade M35 strengthened with SIFCON shell and compared them with unstrengthen NSC. The effect of different SIFCON shell thicknesses (2 and 3) cm, fiber type and volume fraction (4 and 6%), and tie spacing (8 and 16) cm were studied. The fiber types employed were polypropylene and hooked-end steel fiber. Eleven columns were cast and tested for the current investigation in two groups, where the first group (control specimens) consists of two unstrengthen NSC columns and one square NSC column strengthened with a 2 cm SIFCON shell with a 6% steel fiber ratio. The second group comprises eight NSC columns strengthened with a hybrid fiber SIFCON shell. The NSC square columns had dimensions of (8x8x80) cm. 3 cm SIFCON shell thickness was observed to evolve the strengthen columns' load-carrying capacity and energy absorption. The maximum load achieved is about 223% as compared with unstrengthened NSC columns. The energy absorption was about 16 times that of the control. At the same time, the stiffness of strengthened columns is less than that of NSC columns

The Inhibitive Effect of BTA on The Corrosion of Copper Rotating Cylinder Electrode in Oxygenated 0.1M H2SO4 Under Controlled Conditions of Mass Transfer

The inhibitive action of benzotrizole (BTA) on the corrosion of copper inoxygenated 0.1M sulfuric acid solution has been investigated using the rotatingcylinder electrode to provide turbulent conditions. Potentiostatic polarizationmeasurements were carried out at different temperatures of 283,288,293 and 298Kand various speeds of rotation, 100,200,300 and 400 rpm.In general, BTA, at concentration of 0.01M, effectively inhibits the corrosion ofcopper in oxygenated 0.1M sulfuric acid solution. Moreover, BTA effectivelyinhibits the anodic dissolution of copper and the cathodic reactions ,i.e., HER andoxygen reduction reaction. Therefore, BTA acts as a mixed inhibitor inoxygenated solutions.The overall percentage of inhibition efficiency is about 98% . This indicates thata Cu-BTA film is developed on the copper electrode surface which about 98% ofthe corrosion rate . The overall inhibition efficiency is neither affected by theturbulent flow rate , nor by the temperature increases.The corrosion rate is temperature dependent only, which indicates that thecorrosion of copper in inhibited oxygenated 0.1M sulfuric acid solutions is underactivation control