Loss Quantization of Reflectarray Antenna Based on Organic Substrate Materials

This paper presents novel loss quantization of reflectarray elements based on organic substrate materials. Three differently composed substrate materials derived from recycled materials have been characterized for their dielectric properties using a broadband analysis technique. The materials show low dielectric permittivity values of 1.81, 1.62 and 1.84 for X-band frequency range. In order to estimate the reflection loss of for the three substrates a mathematical relation has been established using empirical data generated by computer simulated models. The reliability of the proposed model has been established by simulation and fabrication of unit reflectarray rectangular patch elements on three proposed substrate substrates. A broadband frequency response has been depicted by scattering parameter analysis of unit elements with 10% fractional bandwidth of 312, 340 and 207 MHz for RCP50, RCR75 and RNP50 substrate respectively

Loss quantization of reflectarray antenna based on organic substrate materials

This paper presents novel loss quantization of reflectarray elements based on organic substrate materials. Three differently composed substrate materials derived from recycled materials have been characterized for their dielectric properties using a broadband analysis technique. The materials show low dielectric permittivity values of 1.81, 1.62 and 1.84 for X-band frequency range. In order to estimate the reflection loss of for the three substrates a mathematical relation has been established using empirical data generated by computer simulated models. The reliability of the proposed model has been established by simulation and fabrication of unit reflectarray rectangular patch elements on three proposed substrate substrates. A broadband frequency response has been depicted by scattering parameter analysis of unit elements with 10% fractional bandwidth of 312, 340 and 207 MHz for RCP50, RCR75 and RNP50 substrate respectivel

Virgin kraft pulp and paper characteristics of Vitex Pubescens Vahl. (Halban) wood

Insufficient wood-based materials due to environmental sustainability have further enhanced the search for alternatives in the paper industry. Thus, wood sample from Vitex Pubescens Vahl (Halban) was evaluated based on the pulp characteristics; and paper physical, mechanical and optical properties as alternative raw material for papermaking. The wood chips were chemically Kraft cooked. Laboratory hand sheet with 120 gsm of grammage was produced without beating and bleached treatment. Overall procedures and tests were conducted according to the Technical Association of the Pulp and Paper Industry (TAPPI) and the Malaysian International Organization for Standardization (MS-ISO). The result shows that Halban virgin Kraft pulp recorded a value of screened yield percentage (38.6%), Kappa number (22.1), drainage time (6.44s), and Canadian Standard Freeness (555ml). Halban paper sheet has apparent density of 0.302g/cm3. In an optical analysis, brightness (19.81%) and opacity (99.5%) had been measured. Mechanical characteristic possess considerable tensile index (29.33Nm/g), tear index (6.028 mN.m2/g), burst index (1.04 kPa.m2/g), but low folding no (3). In conclusion, Halban wood could be considered as alternative wood-based material for papermaking based on its promising characteristics’ and also compatible with other wood-based material proposed by the previous study. However, more in-depth evaluation should be considered to improve the qualities of the pulp and paper made from Halban wood

A wideband reflectarray antenna based on organic substrate materials

Significant improvements in terms of bandwidth of reflectarray antennas have been achieved by introduction of innovative paper substrate dielectric materials. Three differently custom composed organic dielectric substrates have been characterized for dielectric properties using a broadband technique based on open ended coax cable method. The substrates show low dielectric permittivities of 1.81, 1.63 and 1.84 along with a loss tangent of 0.053, 0.047 and 0.057. Validation of using the proposed substrates for reflectarray antenna was done by modelling and fabricating reflectarray unit elements on the three substrates. Scattering parameter analysis of unit reflectarray elements show encouraging results with a broadband frequency response of 340 MHz at a phase gradient of 0.14 º/MHz. Thus the proposed substrate could serve exceptionally to address the narrow bandwidth problem in reflectarray antennas

Soda-anthraquinone durian (durio zibethinus murr.) rind linerboard and corrugated medium paper: a preliminary test

A preliminary test was conducted to investigate the characteristics of linerboard and corrugated medium paper made from durian rind waste. Naturally dried durian rinds were pulped according to Soda-Anthraquinone (Soda-AQ) pulping process with a condition of 20% active alkali, 0.1% AQ, 7:1 liquor to material ratio, 120 minutes cooking time and 170°C cooking temperature. The linerboard and corrugated medium paper with a basis weight of 120 gsm were prepared and evaluated according to Malaysian International Organization for Standardization (MS ISO) and Technical Association of the Pulp and Paper Industry (TAPPI). The results indicate that the characteristics of durian rind linerboard are comparable with other wood or non-wood based paper and current commercial paper. However, low CMT value for corrugated medium and water absorptiveness quality for linerboard could be improved in future. Based on the bulk density (0.672 g/cm3), burst index (3.12 kPa.m2/g) and RCT (2.00 N.m2/g), the durian rind has shown a good potential and suitable as an alternative raw material source for linerboard industry

Characterisation of pulp and paper manufactured from oil palm empty fruit bunches and kenaf fibres

In papermaking, blending or mixture of fibres is one of the ways to enhance mechanical properties of paper. The objective of this study was to evaluate the properties of paper manufactured from mixture of oil palm empty fruit bunch (EFB) and kenaf fibres. The papers were prepared according to 10, 30, 50 and 70 percentages of kenaf whole stem blended into oil palm empty fruit bunch fibres. The preparation and testing of papers were carried out based on TAPPI Test Methods. Results showed that using kenaf whole stem fibres improved the mechanical properties of the blended papers and complied with the standard requirement for writing and printing grade paper

Effects of total chlorine free (TCF) bleaching on the characteristics of chemi mechanical (CMP) pulp and paper from Malaysian durian (DURIO ZIBETHINUS MURR.) rind

The effects of bleaching process on the characteristics of pulp and paper produced from durian rind under chemi-mechanical pulping (CMP) method were investigated. All process and characteristic tests were conducted according to Malaysian International Organisation for Standardization (MS ISO) and Technical Association of the Pulp and Paper Industry (TAPPI). Three (3) stages of peroxide (P-P-P) bleaching sequence through the Total Chlorine Free (TCF) bleaching process were applied to the unbeaten and unbleached durian rind CMP pulp. Bleached CMP durian rind pulp drainage time (32s) decreased (faster) and CSF freeness level (172.50ml) increased as compared to a control pulp. It was obtained that overall optical (brightness (66.36 %)) and mechanical characteristics (tensile index (38.33 Nm/g), tearing index (7.56 mN.m2/g), bursting index (2.42 kPa.m2/g), and number of folds (43)) of durian rind CMP 60 gsm paper sheet improved as the TCF bleaching process was applied to the unbleached CMP durian rind pulp

Oil Palm Empty Fruit Bunch (OPEFB) handsheet production from optimized biodelignification of rhynchophorus ferrugineus microbiome’s enzymes

Oil palm plantation generates massive amount of oil palm empty fruit bunch (OPEFB) which source great amount of cellulose. However, wrapping this cellulose is an adhesive compound called lignin. Biodelignification process was applied to remove lignin in pulp and paper industry. Therefore, this study is focused on optimum conditions of delignification process using a combination of bacteria from Rhynchophorus ferrugineus on OPEFB. The composition of chemicals was characterized according to the TAPPI standard method and Kursher-Hoffner method. The Box-Behnken design (BBD) was used to determine the optimum conditions of delignification process based on lignin loss of OPEFB. The optimized fiber was investigated based on mechanical properties according to TAPPI standard methods. From BBD analysis, the finest conditions for delignification were recognized to be at 35 °C in 48 h incubation time with 5 mL of 1% glucose for predicted value 54.3% compared to experimental value 52% of lignin loss as revealed by confirmatory study. The highest result of chemical analysis was recognized at run 12 (1.15%), 10 (12.35%), 4 (48.99%) and 5 (1.28%) for extractive, lignin, cellulose and ash content respectively. The tensile, burst and tear were identified as 9.93 Nm/g, 0.98 kPa.m2/g and 2.57 mN.m2/g respectively for handsheet product at optimum conditions. In conclusion, the results obtained was indicated that the delignification process via bacteria combination from R. ferrugineus is a viable alternative pulping process for pulp and paper-based industry. The delignification process on OPEFB also provides a cleaner technology process and more sustainable development for the country

Effect of microstructure, thermodynamic and operating conditions on performance of membrane distillation

Membrane distillation (MD) is a thermally driven process which only allows vapour molecules to be transported via diffusion through hydrophobic membranes. Although MD has been studied for a few decades since its’ first introduction in 1967, no commercial scale process has been established. Several major factors contribute to the delay in commercialization of MD; namely lack of thorough understanding on the factors affecting MD performance, absence of commercial membranes giving excellent MD performance, lack of good design of membrane modules with good fluid dynamics, lack of membranes with high thermal efficiency and limited information and data on energy requirements and potential application areas. This work was focused on two main technical issues; (i) factors affecting MD performance including terms of membrane microstructure, thermodynamic and operating conditions, and (ii) MD energy requirement. In addressing these factors, PTFE membranes with different pore size, thickness and porosity were subjected to direct contact and vacuum membrane distillation (DCMD and VMD) experiments at different temperatures, feed flow rates, stream flow directions, feed concentrations and vacuum levels. Numerical modeling using Polymath software was carried out to predict how these parameters affect MD performance. The second part of this work presents an engineering process modeling for the estimation of thermal and electrical energy requirements for DCMD and VMD. Finally, the technical feasibility of MD in treating solutions containing volatile organic compounds (VOCs) for application in the pulp and paper industry was studied. Synthetic and actual foul pulping condensates were treated with sweep gas and vacuum membrane distillation (SGMD and VMD) and the flux, VOCs separation factors and removal efficiency were compared. The energy requirements in these two processes were also estimated. Results obtained by this study confirm that membrane porosity is the most important factor affecting MD performance. The structure and porosity of membrane support materials also play important roles in determining the performance of DCMD. Higher fluxes and lower temperature polarizations were observed over membranes with large pore size, low thickness, high porosity and low tortuosity. Membrane porosity, pore size and the presence of support materials were found to have significant effects on flux and temperature polarization. The thermal energy requirement for DCMD is higher compared to VMD, but its electrical energy requirement is significantly lower. For DCMD to be competitive with commercial desalination processes, the system needs to operate in a circulation mode with an available heat source and 85% heat recovery. For VOCs removal from pulp mill’s condensates, SGMD provides higher separation factor and lower risk of membrane wetting. At operating temperatures below 45C, electrical energies between 0.005 and 1.67 kWh/m3 are required. In comparison to SGMD, VMD requires a significant less electrical energy but the separation efficiency is lower

Effect of microstructure, thermodynamic and operating conditions on performance of membrane distillation

Membrane distillation (MD) is a thermally driven process which only allows vapour molecules to be transported via diffusion through hydrophobic membranes. Although MD has been studied for a few decades since its’ first introduction in 1967, no commercial scale process has been established. Several major factors contribute to the delay in commercialization of MD; namely lack of thorough understanding on the factors affecting MD performance, absence of commercial membranes giving excellent MD performance, lack of good design of membrane modules with good fluid dynamics, lack of membranes with high thermal efficiency and limited information and data on energy requirements and potential application areas. This work was focused on two main technical issues; (i) factors affecting MD performance including terms of membrane microstructure, thermodynamic and operating conditions, and (ii) MD energy requirement. In addressing these factors, PTFE membranes with different pore size, thickness and porosity were subjected to direct contact and vacuum membrane distillation (DCMD and VMD) experiments at different temperatures, feed flow rates, stream flow directions, feed concentrations and vacuum levels. Numerical modeling using Polymath software was carried out to predict how these parameters affect MD performance. The second part of this work presents an engineering process modeling for the estimation of thermal and electrical energy requirements for DCMD and VMD. Finally, the technical feasibility of MD in treating solutions containing volatile organic compounds (VOCs) for application in the pulp and paper industry was studied. Synthetic and actual foul pulping condensates were treated with sweep gas and vacuum membrane distillation (SGMD and VMD) and the flux, VOCs separation factors and removal efficiency were compared. The energy requirements in these two processes were also estimated. Results obtained by this study confirm that membrane porosity is the most important factor affecting MD performance. The structure and porosity of membrane support materials also play important roles in determining the performance of DCMD. Higher fluxes and lower temperature polarizations were observed over membranes with large pore size, low thickness, high porosity and low tortuosity. Membrane porosity, pore size and the presence of support materials were found to have significant effects on flux and temperature polarization. The thermal energy requirement for DCMD is higher compared to VMD, but its electrical energy requirement is significantly lower. For DCMD to be competitive with commercial desalination processes, the system needs to operate in a circulation mode with an available heat source and 85% heat recovery. For VOCs removal from pulp mill’s condensates, SGMD provides higher separation factor and lower risk of membrane wetting. At operating temperatures below 45C, electrical energies between 0.005 and 1.67 kWh/m3 are required. In comparison to SGMD, VMD requires a significant less electrical energy but the separation efficiency is lower