Dielectric Cover Layer Thickness Effect on Circular Microstrip Antenna Parameters

This paper studies the effect of dielectric cover layer thickness on circular microstrip patch antenna parameters such as gain, bandwidth, beam-width, radiation patterns, return loss and VSWR. The proposed antenna is designed with 2.4GHz frequency in S-Band region. This operating frequency useful in ISM band applications. Circular patch antenna is designed with cavity model analysis and simulated using HFSS simulation software (Electromagnetic simulator). The coaxial probe fed is used for antenna design. In this paper the effect of dielectric cover layer on antenna parameters studied experimentally and comparing their performance characteristics. The simulation results shows that the antenna without dielectric cover layer obtained gain is 4.11dB and antenna with dielectric cover the gain is reduced to 2.87dB to 5.88dB based on thickness of the dielectric cover layer. The antenna bandwidth obtained without dielectric cover is 3% and with dielectric cover its bandwidth is reduced from 0.012GHz to 0.052GHz based on thickness of the cover layer effect. Similarly other parameters are investigated and compared. This proposed circular patch antenna is used in wireless and Wi-Fi applications.

Experimental Study of Bond Behavior Between Rebar and PVA-Engineered Cementitious Composite (ECC) Using Pull-Out Tests

As a novel civil engineering material, Engineered Cementitious Composite (ECC) has attracted more and more attention due to its strain-hardening characteristics, good post-cracking resistance and its unique properties. Bonding between Engineered Cementitious Composite (ECC) and rebar has a great effect on the mechanical behavior of structural members. In this paper, direct pull-out tests were conducted to understand the bond behavior between the ECC and rebar. The test parameters included rebar diameter and type, cover layer thickness, embedment length and fiber volume content. Bond-slip curves, failure and cracking pattern and bond strength were compared and discussed. The test results indicated that the bond strength decreased with the increase of embedded length. Through regression analysis with the test data, the functional relationships between bond strength and cover layer thickness and rebar diameter were fitted well. According to the positive and negative signs of the fitting parameters m and n, the relationship between the bond strength and the cover layer thickness and the rebar diameter could be determined. The bond strength increased obviously with the increase of fiber content. When the fiber volume content was 1, 1.5 and 2%, the bond strength of these specimens were 1.5, 2.5 and 3.1 times that of specimens without polyvinyl alcohol (PVA) fiber.

Design and technological provision of wear resistance of elastomer surface of rubber-cord casings of damping devices

Two main factors are considered that determining the friction between non-lubricated surfaces of an elastomer and a solid base during their relative motion. The first one is adhesion in the areas of real (actual) catalysis and the second factor is the deformation component, which is due to the delay of recovery of the elastomer after the irregularity is introduced and it is called the hysteresis component of friction. One of the main problems of increasing the resource of pneumatic dampers is minimizing the wear of the covering layer of the rubber-cord casing (RCC). The wear of the RCC is due to the fact that sliding friction occurs in the process of contact between the metal surface and the surface of the RCC, as a result of which the cover layer of the RCC (in some cases with the first cord layer) wears out, depending on the chemical composition of the rubber and the features of the operation of the pneumatic shock absorber. In order to minimize the wear of rubber, it is proposed to change the design of the pneumatic damper so that rolling friction dominates in the contact between the surfaces of rubber and metal

A critical review of the Water Sorptivity Index (WSI) parameter for potential durability assessment: Can WSI be considered in isolation of porosity?

ABSTRACT The Durability Index (DI) approach used in South Africa is linked to transport-related properties of the cover layer of concrete. This performance-based approach utilises three different durability-related parameters, namely Water Sorptivity Index (WSI), Oxygen Permeability Index (OPI) and Chloride Conductivity Index (CCI). In the water sorptivity test, both the sorptivity and the water-penetrable porosity of the concrete are measured. Until now, porosity has not been considered directly as a separate durability-related parameter. This paper analyses these implications and suggests that porosity should be adopted as a further index. The paper concludes that sorptivity cannot be interpreted without also reflecting the porosity value since these two parameters are inter-related. Keywords: concrete durability, durability index, water sorptivity, porosity, absorption

Utilization of Plastic Waste Polyethylene (PET) for reinforced subgrade

Plastic waste is a serious problem for the survival of all creatures on Earth. Recycling is one solution to reduce the negative impact of environmental pollution caused by plastic waste. A lot of plastic waste that pollutes the Earth comes from plastic bottle waste (PET). There had been many studies that discussed the use of plastic bottle waste (PET); however, this research used the plastic bottle waste (PET) as a geocell for subgrade reinforcement. To this date, the use of plastic bottle waste as geocell is still rare. The main purpose of this study was to determine the effect of adding geocell of plastic bottle waste on the subgrade using a capping layer that had a low bearing capacity. This research was expected to reduce the impact of environmental pollution due to plastic bottle waste, and be an alternative solution for additional reinforcement in the capping layer. Therefore, it could increase the ultimate bearing capacity and reduce the thickness of the cover layer on subgrades that had a CBR value below 5%. The results of the analysis using the Plaxis program showed that the geocell from plastic bottle waste could be used to save the use of capping layer materials by up to 65%.