Design Synthesis of 5.8 GHz Octagonal AMC on a Very Thin Substrate

This paper proposed a development of 5.8 GHz Artificial Magnetic Conductor, AMC using very thin substrate with thickness of 0.13 mm. Different shapes of PEC metallization are discussed in order to achieve the highest bandwidth of unit cell AMC. Another approaches for increasing the bandwidth is by applying the ring patch around the substrate as well as implementing the DGS ground plane. The proposed design produces 1.96 % bandwdith of unit cell. Applying the 2 x 4 unit cell arrangement gives the best result for directivity equal to 6.75 dBi, gain of 6.83 dB, efficiency = 98.41 % and return loss = -45.63 dB

Design of Stacked Wafers AMC at 920 MHz for Metallic Object Detection in RFID Application

Artificial Magnetic Conductor, AMC is introduced into RFID application to overcome the problem of metal object detection. The AMC act as the Perfect Magnetic Conductor, PMC exhibits a reflectivity of +1 (in-phase reflection). In this paper, the stacked wafers AMC structure is designed to operate at 920 MHz frequency. The proposed stacked wafers AMC is an evolution from the basic square patch AMC. By introducing different size of slots into the square patch will help to reduce the frequency hence increase the bandwidth of the reflection phase. Another method to increase the bandwidth is by increasing the thickness of the structure. For the single cell of stacked wafers AMC proposed in this paper, the simulated bandwidth is 3.5% with reduced size of 45.56% than the square AMC. An optimized structure of 3x2 stacked wafers AMC give better return loss = - 21.8 dB and gain = 3.04 dB with total efficiency of 82.3%

Effects of Particulate Types on Biomass Particulate Filled Kenaf/Polypropylene Composite

The application of natural fibers in composite is very encouraging because of its many benefits such as more environmental friendly and cost reduction. Recently, there is an interest on the application of kenaf-based material for high-end uses such as in automotive industry. In this research, mechanical properties of kenaf fiber reinforced polypropylene (KFRP) composite added with two different types of bio-based fillers, i.e., oil palm shell particle (OPSP) and rubber seed shell particle (RSSP) are studied. The composites were prepared by melt mixing of the materials using internal mixer, followed by compression molding process using hot press machine. The tensile and flexural strength were found to increase with the addition of OPSP as well as RSSP. However, KFRP composite added with RSSP showed better tensile, flexural and impact properties as compared to the composite added with OPSP. From microscopic observation of the raw OPSP and RSSP particles, it was observed that OPSP showed a more granular shape, while RSSP particles were flakier in shape. The difference in particle shape is believed to affect the mechanical properties of the composites as demonstrated in this study

Recent progress of electrode architecture for MXene/MoS2 supercapacitor: preparation methods and characterizations

Since their discovery, MXenes have conferred various intriguing features because of their distinctive structures. Focus has been placed on using MXenes in electrochemical energy storage including a supercapacitor showing significant and promising development. However, like other 2D materials, MXene layers unavoidably experience stacking agglomeration because of its great van der Waals forces, which causes a significant loss of electrochemically active sites. With the help of MoS2, a better MXene-based electrodecan is planned to fabricate supercapacitors with the remarkable electrochemical performance. The synthesis of MXene/MoS2 and the ground effects of supercapacitors are currently being analysed by many researchers internationally. The performance of commercial supercapacitors might be improved via electrode architecture. This analysis will support the design of MXene and MoS2 hybrid electrodes for highly effective supercapacitors. Improved electrode capacitance, voltage window and energy density are discussed in this literature study. With a focus on the most recent electrochemical performance of both MXene and MoS2-based electrodes and devices, this review summarises recent developments in materials synthesis and its characterisation. It also helps to identify the difficulties and fresh possibilities MXenes MoS2 and its hybrid heterostructure in this developing field of energy storage. Future choices for constructing supercapacitors will benefit from this review. This review examines the newest developments in MXene/MoS2 supercapacitors, primarily focusing on compiling literature from 2017 through 2022. This review also presents an overview of the design (structures), recent developments, and challenges of the emerging electrode materials, with thoughts on how well such materials function electrochemically in supercapacitors

Electroless Ni-Co-Cu-P Alloy Deposition in Alkaline Hypophosphite Based Bath

The use of electroless deposition method to deposit nickel alloy attracts attention due to its uniformity, corrosion resistance in neutral media and low friction. Quaternary nickel alloy deposit can be achieved by adding metal ion additive into the plating bath. Furthermore, the use of alkaline bath can accelerate the deposition rate, and provide sufficient thickness for corrosion protection. In this study, an electroless quaternary nickel alloy is deposited on iron coupons by adding cobalt and copper ions in hypophosphite based Ni-P alkaline bath. The nickel alloy deposit surface morphology is studied using scanning electron microscope (SEM) and x-ray fluorescence(XRF). Corrosion behavior of the nickel alloy is investigated using polarization curve measurement in 3.5wt% NaCl aqueous solution. From the results, the elecroless Ni-Co-Cu-P alloy coating produced at higher plating bah pH is harder than the lower bath pH. Higher Co, Cu and P content in the Ni alloy exhibit broader passive area in the polarization curve measurement results

A Facile Coating Method for Superhydrophobic Magnetic Composite Sheet from Biodegradable Durian Peel for Electromagnetic Wave Absorbance Application

Most of the electromagnetic (EM) wave absorbers are commonly made from polymerbased materials. A large number of polymers are resistant to the environmental degradation and are thus responsible for the buildup of polymeric solid waste materials. These solid wastes cause acute environmental problems and remain undegraded for quite a long time. In a view of the awareness and concern for the problems created by the polymeric solid wastes, new biodegradable cellulosic composite with low cost and nontoxic materials, have been designed and developed. However, the properties of natural fibers that tends to absorb water, thus limiting their application. In this study,precipitated calcium carbonate (PCC) was added with stearic acid (SA) in order to generate a hydrophobic coating formulation. PCC works as filler and SA acts as surface hydrophobic modification agent. Polymer latex was then added to the coating compound as the binder. The composite surface morphology was inspected using scanning electron microscope (SEM). Results show that durian peel composite sheet had successfully achieved a superhydrophobic surface with a water contact angle of 154.85° which exceed 150°

Direct Observation Of Graphene During Raman Analysis And The Effect Of Precursor Solution Parameter On The Graphene Structures

Controlling the precursor solution parameter in preparing active catalyst film is critical in sol-gel process. The aim of this work is to validate the precursor solution parameter that affects the structural properties of graphene. Active Co3O4 film was prepared using precursor solution from cobalt acetate tetrahydrate in two different concentrations; 0.025 M and 0.05 M. One batch of the precursor solution was directly spin coated onto the substrate's surface meanwhile the second batch was kept for 4 days aging process. The studied spin speeds were 2000 rpm and 6000 rpm, and spin coated for 60 s. The active Co3O4 film was achieved by annealing at 450 °C and the graphene was grown at 900 °C of chemical vapor deposition (CVD) processing temperature for 5 min with the presence of ethanol as the carbon feedstock. The structural properties and morphology of the as-grown graphene synthesized from active Co3O4 film were characterized by Raman spectroscopy, optical microscope, and field emission scanning electron microscope (FESEM). The results demonstrated that concentration of precursor solution and the aging process affected the performance of the as-grown graphene. Agglomerates were formed in sample with 0.05 M of Co acetate tetrahydrate, however it was found that the Raman peaks intensity increased as compared to the 0.025 M sample. The precursor with 0.05 M has an acceptable chemical stability though aged for 4 days and contributed to the graphene growth. The spin coating speed was found not to affect the graphene growth at all. For aging effect, concentration 0.025 M shows unstable condition as compared to concentration 0.05 M when the precursor solution was aged for 4 days. Nonetheless, for the quality of the as-grown graphene, the ratio of Raman 2D-band over G-band intensities was less than 1.0, indicated that the graphene was in multi-layer form

Effect Of Different Cooking Temperature And Alkalinity On Mechanical And Morphological Properties Of Composite Sheet From Durian Shell

Temperature and alkalinity are the critical factors that contribute to the successful of soda pulping. These factors influence the length size and interfibre bonding of the fibre. In this paper, durian (Durio zibethinus Murray) shell composite sheet were prepared by conducting chemical pulping through soda method to study the effect of different pulping temperature and % of NaOH on the mechanical and morphological characteristics of durian shell composite sheet. Six sets of composite sheet were produced from six sets of pulping. The pulping processes were conducted at 140, 160 and 170°C with 17, 19 and 21% of active alkali. The mechanical properties of the durian shell composite sheet were analyzed through few standard TAPPI analyses which are tensile, tear, burst, folding endurance and paper bulk thickness. The results show that the highest reading of paper bulk thickness, tensile, tear and burst index, and also folding endurance were achieved at the pulping condition of 170°C with 21% of NaOH with the value of 1.3366 g/cm3, 54.151 NM/g, 6.648 m.Nm2/g, 2.517 k.Pam2/g and 170 no. of fold, respectively. Scanning electron microscopic analysis showed that morphological changes took place depending on the size and arrangement of the fibres in the composites sheet

Influence Of Pulping Process Conditions Towards Better Water Resistant Effect Of Durian Shell Paper By Lignin: Two Level Factorial Design Approach

Chemical pulping of durian shell fiber is a comparatively new approach in the field of pulping, and the paper industry as a whole. Pressures of rising wood resource consumption have resulted in increased attention on the use of non-wood raw materials in the papermaking industry. This situation is due to trees being exploited in high numbers for the purpose of paper manufacturing. Thus, some alternative solutions have been developed to remedy this. Natural resources wastes like kenaf, bamboo and sugarcane bagasse are used as the raw material to produce these varied grades of paper. Additionally, cellulose fiber possesses a natural tendency to absorb moist and water vapor from the surrounding, producing weak mechanical properties and limiting paper's use. Therefore, in this study, lignin acts as a natural plasticizer in plant cell wall has been optimized to overcome the hygroscopic issue. An optimal amount of lignin will generate maximum hydrophobic effect to prepare for the production of water resistant paper. The process is optimized under the influence of three operational variables; 1) % of NaOH, 2) cooking temperature, and 3) period of cooking. To analyze the response, two level factorial design method by Design Expert v.6.0.8 software has been used. The results show that the highest water contact angle reading of 70.33° has been achieved at the condition of 17 % alkalinity, 140 °C of cooking temperature and 120 min of cooking period. At the same process condition, the highest amount of lignin (57.67 %) has also been obtained which showing the significant interaction between lignin and the hydrophobic effect. From the analysis of variance (ANOVA), all parameters have significantly affected the reading of water contact angle. The P-value of the experiment model is less than 0.0001 and the coefficient of determination value (R2) is 1.000. This conclusively suggested that the model is significant and influences on the precision and process-ability of the production