Formulas of General Solution for Linear System from Ordinary Differential Equations by Using Novel Transformation

In this work, we use Novel transform which has the form  to solve a system of linear differential equations, while homogeneous or non-homogeneous system. Moreover, general formula of the set solution of systems of first and second order are derived

The Role of Nano Particles Additives on The Wear Properties of Al-Pb alloy

The Al-Pb alloy is one of the important alloys, especially for bearings materials. The main problem of Al-Pb alloy is the difference in melting point and immiscibility between aluminum and lead. In this research mechanical alloying method was used to produce Al- 10%Pb- 4.5%Cu by mixing the constituent in a ball mill under argon atmosphere for two hours at 150 rpm , then it was pressed with different applied loads (44100, 49000, 53900, 58800 and 63700N) and at three sintering temperatures (350, 450 and 550℃). The results show that sintering temperature was  the main factor affecting on the microstructure of alloy. The grain size was reduced with increasing sintering temperature and applied load. The results revealed that the best hardness and compressive strength was obtained with 58800N applied load and 450℃ sintering temperature due to the formation of CuAl2 as well as good distribution of Pb. Alumina in a form of micro and nano particles size resulted in a decline in hardness and wear resistance, while micro Al2O3 improved compressive strength and then decreased at high concentration (2wt. %). The addition of micro and nano SiC resulted in  reduced hardness. Micro SiC improves wear resistance and slightly improved the compressive strength while nano SiC increased to some extent the compression strength and reduced wear resistance. The grains size decreased with the increase of the percentage of Al2O3 and SiC (micro and nano) until 1.5% Al2O3 and 1%SiC addition. X-ray diffraction indicated the formation of new Al-Cu intermetallic compound (Cu9Al4) in the alloy containing Al2O3 or SiC associated with disappears of CuAl2. Keywords: Mechanical alloying, Sintering, SEM, EDS, hardness, compressive strength, Wear.

Experimental Investigation of Circular High-Strength Concrete Columns Reinforced with Glass Fiber-Reinforced Polymer Bars and Helices under Different Loading Conditions

Existing design codes and guidelines do not adequately address the design of concrete columns reinforced with fiber-reinforced polymer (FRP) bars. Accordingly, a number of research studies investigated the behavior of FRP bar-reinforced concrete columns. However, the previous studies were limited to FRP bar-reinforced normal-strength concrete (NSC) columns. In this study, the behavior of glass fiber-reinforced polymer (GFRP) bar-reinforced high-strength concrete (HSC) specimens under different loading conditions was investigated in terms of axial load-carrying capacity, confinement efficiency of the GFRP helices, as well as the ductility and post-peak axial load-axial deformation response. The effects of the key parameters such as the type of the reinforcement (steel and GFRP), the pitch of the transverse helices, and the loading condition (concentric, eccentric, and four-point loading) on the performance of the specimens were investigated. It was observed that the GFRP bar-reinforced HSC specimen sustained similar axial load under concentric axial compression compared to its steel counterpart, but the efficiency of GFRP bar-reinforced HSC specimens in sustaining axial loads decreased with an increase in the axial load eccentricity. Direct replacement of steel reinforcement by the same amount of GFRP reinforcement in HSC specimens resulted in about 30% less ductility under concentric axial load. However, it was found that the ductility and post-peak axial load-axial deformation behavior of the GFRP bar-reinforced HSC specimens can be significantly improved by providing closely spaced helices

Maximum axial load carrying capacity of Fibre Reinforced-Polymer (FRP) bar reinforced concrete columns under axial compression

In this study, a new equation is proposed to compute the maximum axial load carrying capacity of FRP bar reinforced concrete columns under axial compression. The equation proposed in this study was critically compared with the equations proposed in the previous research studies using a wide range of experimental data taken from the available literature. In general, it was found that computing the contribution of the FRP longitudinal bars in concrete columns based on the modulus of elasticity (stiffness) of the FRP bars provides more rational predictions than computing the contribution of the FRP longitudinal bars based on the ultimate tensile strength of the FRP bars. It was also found that using a concrete compressive strength-based empirical equation in estimating the axial strain in the FRP longitudinal bars in concrete columns provides more accurate predictions of the contribution of the longitudinal FRP bars in the axial load sustained by the FRP bar reinforced concrete columns

Parallelizing Navier-Stokes Computations on a Variety of Architectural Platforms

We study the computational, communication, and scalability characteristics of a Computational Fluid Dynamics application, which solves the time accurate flow field of a jet using the compressible Navier-Stokes equations, on a variety of parallel architectural platforms. The platforms chosen for this study are a cluster of workstations (the LACE experimental testbed at NASA Lewis), a shared memory multiprocessor (the Cray YMP), distributed memory multiprocessors with different topologies-the IBM SP and the Cray T3D. We investigate the impact of various networks, connecting the cluster of workstations, on the performance of the application and the overheads induced by popular message passing libraries used for parallelization. The work also highlights the importance of matching the memory bandwidth to the processor speed for good single processor performance. By studying the performance of an application on a variety of architectures, we are able to point out the strengths and weaknesses of each of the example computing platforms

Parallel Navier-Stokes computations on shared and distributed memory architectures

We study a high order finite difference scheme to solve the time accurate flow field of a jet using the compressible Navier-Stokes equations. As part of our ongoing efforts, we have implemented our numerical model on three parallel computing platforms to study the computational, communication, and scalability characteristics. The platforms chosen for this study are a cluster of workstations connected through fast networks (the LACE experimental testbed at NASA Lewis), a shared memory multiprocessor (the Cray YMP), and a distributed memory multiprocessor (the IBM SPI). Our focus in this study is on the LACE testbed. We present some results for the Cray YMP and the IBM SP1 mainly for comparison purposes. On the LACE testbed, we study: (1) the communication characteristics of Ethernet, FDDI, and the ALLNODE networks and (2) the overheads induced by the PVM message passing library used for parallelizing the application. We demonstrate that clustering of workstations is effective and has the potential to be computationally competitive with supercomputers at a fraction of the cost

Severe deterioration in sperm parameters and testes of rats administered naproxen and diclofenac at pre-puberty: An experimental study

Background: Although naproxen and diclofenac are the most commonly used nonsteroidal drugs, their toxicity affecting male reproductivity has not been sufficiently studied, particularly when used in pre-puberty. Objective: This study aims to investigate the toxic effects of naproxen and diclofenac on sperm parameters and testes in pre-pubertal rats. Materials and Methods: In this experimental study, 15 pre-pubertal male albino rats (aged 5 wk, weighted 70-80 gr) were used. The animals were divided in to 3 groups (n = 5/each) of control (0.1 ml dimethyl sulfoxide), naproxen (50 mg/kg), and diclofenac sodium (5 mg/kg), and were orally administered with these drugs every day for 3 wk. Epididymal spermatozoa were taken to assess sperm count, viability, and morphology. After preparing tissue sections, testicular histopathological and histomorphometric analyses were performed. Results: The body weights of rats in both naproxen and diclofenac groups significantly decreased (p < 0.001 and p = 0.03, respectively) in comparison to the control group. Remarkably, the testis weight and total sperm number significantly decreased (p = 0.002, and p = 0.004 respectively) in the naproxen-administered rats only. The sperm viability percentage decreased significantly in both diclofenac and naproxenadministered groups (p ≤ 0.001 and p = 0.03 respectively). Moreover, there was a significant increase (p < 0.001) in the percentage of sperm morphological anomalies in both drug-administered groups. Also, the histological and morphometric findings exhibited severe histopathological appearances in the testes and seminiferous tubules parameters in both drug-administered groups. Conclusion: Naproxen and diclofenac administrations of rats before their puberty induce considerable harm to sperm parameters and testicular histology and morphometry. These severe toxic effects can lead to potential infertility. Key words: Male infertility, Nonsteroidal drugs, Pathology, Spermatozoa, Testis

An Improved Simulated Annealing Technique for Enhanced Mobility in Smart Cities

Vehicular traffic congestion is a significant problem that arises in many cities. This is due to the increasing number of vehicles that are driving on city roads of limited capacity. The vehicular congestion significantly impacts travel distance, travel time, fuel consumption and air pollution. Avoidance of traffic congestion and providing drivers with optimal paths are not trivial tasks. The key contribution of this work consists of the developed approach for dynamic calculation of optimal traffic routes. Two attributes (the average travel speed of the traffic and the roads’ length) are utilized by the proposed method to find the optimal paths. The average travel speed values can be obtained from the sensors deployed in smart cities and communicated to vehicles via the Internet of Vehicles and roadside communication units. The performance of the proposed algorithm is compared to three other algorithms: the simulated annealing weighted sum, the simulated annealing technique for order preference by similarity to the ideal solution and the Dijkstra algorithm. The weighted sum and technique for order preference by similarity to the ideal solution methods are used to formulate different attributes in the simulated annealing cost function. According to the Sheffield scenario, simulation results show that the improved simulated annealing technique for order preference by similarity to the ideal solution method improves the traffic performance in the presence of congestion by an overall average of 19.22% in terms of travel time, fuel consumption and CO2 emissions as compared to other algorithms; also, similar performance patterns were achieved for the Birmingham test scenario

Enhancing chaos in multistability regions of Duffing map for an asymmetric image encryption algorithm

We investigate the dynamics of a two-dimensional chaotic Duffing map which exhibits the occurrence of coexisting chaotic attractors as well as periodic orbits with a typical set of system parameters. Such unusual behaviors in low-dimensional maps is inadmissible especially in the applications of chaos based cryptography. To this end, the Sine-Cosine chaotification technique is used to propose a modified Duffing map in enhancing its chaos complexity in the multistable regions. Based on the enhanced Duffing map, a new asymmetric image encryption algorithm is developed with the principles of confusion and diffusion. While in the former, hyperchaotic sequences are generated for scrambling of plain-image pixels, the latter is accomplished by the elliptic curves, S-box and hyperchaotic sequences. Simulation results and security analysis reveal that the proposed encryption algorithm can effectively encrypt and decrypt various kinds of digital images with a high-level security.Comment: 15 pages, 15 figure

Flotation of Chromium Ions from Simulated Wastewater Using Air Microbubbles

   A microbubble air flotation technique was used to remove chromium ions from simulated wastewater (e.g. water used for electroplating, textiles, paints and pigments, and tanning leather). Experimental parameters were investigated to analyze the flotation process and determine the removal efficiency. These parameters included the location of the sampling port from the bottom of the column, where the diffuser is located to the top of flotation column (30, 60, and 90 cm), the type of surfactant (anionic, SDS, or cationic, CTAB) and its concentration (5, 10, 15, and 20 mg/L), the pH of the initial solution (3, 5, 7, 9, and 11), the initial contaminant concentration (10, 20, 30, and 40 mg/L), the gas flow rate (0.1, 0.2, 0.3, and 0.5 L/min), and the contact time (5, 10, 15, 20, 25, 30, and 35 min). The experimental results revealed that the highest removal efficiency (95%) was achieved in 20 min with a pH of 7, a flow rate of air 0.5 L/min, an SDS surfactant concentration of 15 mg/L, and a pollutant concentration of 30 mg/L at a sampling port height of 30 cm. The use of microbubbles in comparison to normal bubbles, resulted in a 56% improvement of the removal efficiency. The flotation process follows a first-order kinetics