An Electronically Reconfigurable Patch Antenna Design for Polarization Diversity with Fixed Resonant Frequency

In this paper, an electronically polarization reconfigurable circular patch antenna with fixed resonant frequency operating at Wireless Local Area Network (WLAN) frequency band (2.4-2.48 GHz) is presented. The structure of the proposed design consists of a circular patch as a radiating element fed by coaxial probe, cooperated with four equal-length slits etched on the edge along x-axis and y-axis. A total of four switches was used and embedded across the slits at specific locations, thus controlled the length of the slits. By activating and deactivating the switches (ON and OFF) across the slits, the current on the patch is changed, thus modifying the electric field and polarization of the antenna. Consequently, the polarization excited by the proposed antenna can be switched into three types, either linear polarization, left-hand circular polarization or right-hand circular polarization. This paper proposes a simple approach that able to switch the polarizations and excited at the same operating frequency. Simulated and measured results of ideal case (using copper strip switches) and real case (using PIN diode switches) are compared and presented to demonstrate the performance of the antenna

Permeability and tensile strength of concrete with Arabic gum biopolymer

The use of materials of vegetal origin is increasingly being promoted in many industries due to their cost effectiveness and the rising sensitivity to environmental protection and sustainability. Arabic Gum Biopolymer (AGB) is a wild plant byproduct that is abundantly found in Sudan and is also produced in other African countries. It has long been used in various industries. However, its utilization is very limited in the construction sector although there appears to be a significant potential for use of AGB in the building industry. As an example, there is evidence that AGB may be an effective additive to concrete mixes that would improve fresh and hardened concrete properties. The aim of the present work is to provide further experimental evidence on the improvement that can be achieved in the physical and mechanical properties of hardened concrete when AGB is added to the mixture. The experimental results show a significant reduction in permeability for an optimum percentage of AGB and an increase in flexural and tensile strength and in the elastic modulus

Permeability and tensile strength of concrete with Arabic gum biopolymer

The use of materials of vegetal origin is increasingly being promoted in many industries due to their cost effectiveness and the rising sensitivity to environmental protection and sustainability. Arabic Gum Biopolymer (AGB) is a wild plant byproduct that is abundantly found in Sudan and is also produced in other African countries. It has long been used in various industries. However, its utilization is very limited in the construction sector although there appears to be a significant potential for use of AGB in the building industry. As an example, there is evidence that AGB may be an effective additive to concrete mixes that would improve fresh and hardened concrete properties. The aim of the present work is to provide further experimental evidence on the improvement that can be achieved in the physical and mechanical properties of hardened concrete when AGB is added to the mixture. The experimental results show a significant reduction in permeability for an optimum percentage of AGB and an increase in flexural and tensile strength and in the elastic modulus

Effects of fuel ratio on performance and emission of diesel-compressed natural gas (CNG) dual fuel engine

Recent research breakthrough reveals that diesel-CNG dual fuel (DDF) combustion can potentially reduce exhaust emission of internal combustion engines. However, problem arises when knock phenomenon occurs producing high carbon monoxide (CO) and hydrocarbon (HC) emission due to uncontrolled blending ratio of diesel-CNG fuel on specific engine load. This study will determine the limit of dual fuel ratio before knock occurrence while analysing performance and exhaust emission of an engine operating with diesel and DDF fuel mode. A 2.5 litre 4-cylinder direct injection common-rail diesel engine was utilised as a test platform. The modelstested were 100% Diesel, 90% DDF, 80% DDF and 70% DDF, representing diesel to CNG mass ratio of 100:0, 90:10, 80:20 and 70:30 respectively. It was found that DDF engine performance was lower compared to diesel engine at 1500 rpm engine speed. At higher engine speed, the 70% DDF showed engine performance comparable to diesel engine. However, high HC emission with knock onset and a decrease of Nitrogen Oxide (NOX) emission were recorded. This study suggests the preferred limit of dual fuel ratio should not be lower than 70% DDF which will be able to operate at high engine speed without the occurrence of knock and poor exhaust emission

Vibration Signature of Roller Bearing’s Faults

Centrifugal pumps are widely used in many industrial applications. Defective pumps cause higher rate of energy loss with related overall performance degradation. Mechanical components fail due to decrease in pump’s strength or an increase in the force acting on it. Rolling bearings are one of the major components of the centrifugal pumps. Bearings are critical mechanical components in industrial machines. Bearing failure is often attributed to be one of the major causes of breakdown. Early detection of undesired conditions during the operation of the centrifugal pump has become very important in order to avoid consequential damages. Early detection is also vital for increasing availability and reliability. Automated health monitoring can reduce the outage time and repair costs. Using vibration analysis technique to monitor and evaluate the health of the machines has become an important technique in this field. In this research, we studied the vibration signatures of healthy and faulty conditions of the bearings of a pumping system. The pumping system consists of centrifugal pump and electrical motor. The vibration signatures analyze the bearing status with respect to the normal operation. The paper shows how to identify if there is a problem in the outer race of the Bearing Pass Frequency Outer Race (BPFO)

An Overview and Tutorials on Modeling and Simulation

The modeling and simulation are the most important challenges to the researcher to present the system reality and study the different metrics of it. This article provides the short overview to assist the new researchers toward their goals. With aid of differ scenarios related to an engineering domain the designers have an ability to answer critical questions about modeling and simulation

Physiochemical Characteristic and Biological Activity of the Clove (Syzygium aromaticum) Bud Oil

  The present study was investigating the physiochemical and the biological activity of the Clove bud oil against the fungus (A. niger) and two bacteria (E. coli and Staph. aurues). The inhibition zone plate method was used for bacterial test, while the mycelia weights and radial growth methods were used for the fungal study. The A.O.S. official methods were used to determine the physiochemical properties. The studies on the physiochemical characteristics of the Clove bud oil proved that the acid value was (3.86), the saponification value was (38.27),the peroxide value was (3.83), the specific gravity was (1.043), the  reflective index was (1.525), the iodine value was (182.43), and the free fatty acid was (1.94). The results of the antimicrobial tests showed that  the  Clove bud oil gave a complete inhibition of the radial growth of the fungus (A. niger) at its higher concentration and a high reduction percent at its lower concentrations. However, the mycelial fresh and dry weights of the fungus A. niger were completely inhibited by the Clove bud oil at its higher concentration, and clearly reduced at its lower concentrations. The inhibition zone of growth of both bacteria was larger than that of the control treatment. Clove bud oil showed clear inhibition zone when used against Staph. aurues compared to its use against E. coli. Many studies have reported that oils of different herbs and spices can yield medicinal compounds. Spices and herbs have been used for thousand of years by man in traditional medicine. However, more physiochemical characterizations need to be done and the antifungal and the antibacterial properties should be verified in any further studies on the Clove bud oil.   &nbsp