Dielectric Properties of Oil Palm Mesocarp at Various Stages of Maturity

Dielectric properties at frequencies from 10⁻² to 10⁶ Hz and 0.2 to 20 GHz of mashed mesocarp of oil palm fruits at various stages of maturity are presented. The study includes the variation of dielectric constant, ɛ" and dielectric loss, ɛ" with moisture content ranging from 40 to 100% (wet basis). Measurement of the dielectric properties was done by using open-ended coaxial line probe and automated network analyzer for high frequency and spectrum analyzer for low frequency. The accuracy of the measurement is about 5% for dielectric constant, ɛ" and 3% for dielectric loss, ɛ". Results of measurements demonstrate a good relationship between dielectric properties of the mesocarp and moisture content or maturity of the fruit and also close to the values predicted by dielectric mixture models especially at frequencies above 3 GHz. At 10 GHz the difference between predicted and measured values are within 5%. Results of measurement also show that the ac ionic conductivity dominated in the region less than 3 GHz while above 3 GHz the dipole orientation of water molecules becomes dominant. Such a crossover in the form of dielectric loss from conductive loss to the dipole orientation about 2 GHz was observed. The effect of ac ionic conductivity is higher in young fruit and decreasing as a degree of maturity increases. Permittivity of oil palm mesocarp over the frequency range was found to increase with moisture content. A significant variation of ɛ' and ɛ" with maturity at 0.2 GHz and 10 GHz respectively make it suitable to form a maturity index as suggested by Nelson et al. With moisture content ranging from 25% to 85%, the ɛ' at 2 GHz varies from 11 to 61 and the ɛ" varies from 2.1 to 24.6 at 10 GHz. Based on the above values the permittivity-based maturity index for young and fully ripe fruits are 1 and 0.3 respectively

PERFORMANCE COMPARISON BETWEEN ANALYTICAL ANALYSIS AND NUMERICAL SIMULATIONS FOR AVERAGE SOLITON SYSTEM

This paper presents the comparison between analytical results and computer simu lated results showing the performance of soliton transmission in optical fibre optics . A study of average soliton systems with 50 km amplifier spacing is presented both analytically and numerically. The effect of modifying the existing rule of thumb formulae is presented in terms of a design diagram. Th is is then compared to the numerical simu lations. A series of design diagram with Gordon-Haus (GH) jitter, signal to noise ratio (SNR) and soliton collapse limited transmission is also introduced

The generation of dual wavelength pulse fiber laser using fiber bragg grating

A stable simple generation of dual wavelength pulse fiber laser on experimental method is proposed and demonstrated by using Figure eight circuit diagram. The generation of dual wavelength pulse fiber laser was proposed using fiber Bragg gratings (FBGs) with two different central wavelengths which are 1550 nm and 1560 nm. At 600 mA (27.78 dBm) of laser diode, the stability of dual wavelength pulse fiber laser appears on 1550 nm and 1560 nm with the respective peak powers of -54.03 dBm and -58.00 dBm. The wavelength spacing of the spectrum is about 10 nm while the signal noise to ratio (SNR) for both peaks are about 8.23 dBm and 9.67 dBm. In addition, the repetition rate is 2.878 MHz with corresponding pulse spacing of about 0.5 μs, is recorded

Metadiscourse in the academic writing of local and international students at a university in Malaysia

This study examines the use of metadiscourse markers among 50 Malaysian and 50 Arab Pre-University students. The findings of this study indicated that there was a significant difference in the use of metadiscourse markers between Malaysian and Arab Pre-University students {χ2 (1, n = 100) = 7.17, p-value is .007} where the use of metadiscourse markers among Malaysian Pre-University students was substantially higher than that of the Arab Pre-University students. In the use of interactive markers, the results showed significant differences between Malaysian and Arab Pre-University students in the use of transitions, evidential and code glosses. Additionally, in the use of interactional markers, Malaysian and Arab students differed in their use of hedges, engagement markers and self-mentions. These variances in the frequency and forms of metadiscourse markers utilized by the students could be attributed to the diverse cultural backgrounds of the two groups of students. It is therefore suggested that English language teachers integrate and incorporate cultural elements in their lessons with regard to metadiscourse markers

Engineering properties of ring shaped polytheylene terephthalate (RPET) fiber self-compacting concrete

Polyethylene terephthalate (PET) bottles are plastic containers that are typically discarded, and thus, cause environmental pollution. To solve this problem, PET bottles are recycled in concrete. Previous studies have mostly used PET with straight or irregularly shaped fibers. It has been shown that PET has a weak interfacial bond with cement paste in the pullout load because of the lamellar shape of fibers. Therefore, ringshaped PET (RPET) fibers are introduced in this study to overcome the limitations of traditional straight, lamellar, or irregularly shaped fibers. RPET fibers are mainly designed with a special shape to mobilize fiber yielding rather than fiber pullout. RPET fibers are made directly from waste bottles. The diameter of RPET bottles is fixed at 60 ± 5 mm. The width of RPET fibers is fixed at 5, 7.5, or 10 mm and designated as RPET-5, RPET-7.5, and RPET-10 respectively. This study mainly determines the optimum water– binder ratio and fiber content of RPET fiber concrete (FC) through self-compacting, as well as through compressive, tensile, and toughness strength tests. A water–binder ratio of 0.55 and working ranges from 0.25% to 1% of fiber content are successfully accepted for all sizes of RPET fibers. Result of the pullout test shows that RPET fiber interfacial bond strength ranges from 0.502 MPa to 0.519 MPa for RPET-5 fiber, from 0.507 MPa to 0.529 MPa for RPET-7.5 fiber, and from 0.516 MPa to 0.540 MPa for RPET-10 fiber. This study presented that the compressive and tensile strength of RPET fiber exhibited an increase of 17.3% and 35.7%, respectively compared to normal concrete. RPET FC shows improvement in first crack load for flexural toughness strength of RPET FC with increase of 24.5% compared to normal concrete specimen. Moreover, 156 FC cylinders were used to develop new equations for predicting the compressive and tensile strengths of RPET FC via multiple regression analysis. Two equations are obtained. These equations are included in calculating compressive and tensile strength of RPET FC limited up to 28 days In conclusion, incorporating RPET fibers when recycling waste PET bottles in concrete produces FC with An improvement performance comparable to that of normal concrete

Saturable absorption measurement of platinum as saturable absorber by using twin detector method based on mode-locked fiber laser

This paper illustrates the absorption measurement of Pt as saturable absorber (SA) by using mode-locked fiber laser system. The SA is fabricated by depositing 10 nm of Pt on the fiber ferrules using sputtering method. The absorption measurement of Pt is characterised by employing a balanced twin detector method based on mode-locked fiber laser with central wavelength of 1532.25 nm, repetition rate of 2.833 MHz and pulse duration of 34.3 ns. The Pt-SA produce modulation depth of 21.9% and saturation intensity of 21.6 MW cm-2

Generation of four-wave mixing in a highly non-linear optical fiber using a tunable dual wavelength fiber laser source

In this paper, we demonstrate a Four Wave Mixing (FWM) effect in a highly nonlinear single mode optical fiber. A tunable dual-wavelength fiber laser is used to provide the pump and signal probe to generate partially degenerate FWM. Calculations using coupled differential equations and experimental results in the generation of FWM were analyzed. We observed that FWM conversion efficiency depends more significantly on the wavelength detuning between pump and signal wavelength as compared to zerodispersion wavelength. The tunability is achieved using an arrayed waveguide grating which provides different wavelength combinations of the dual-wavelength fiber laser output and can be tuned from 1530.47nm to 1548.61nm with a spacing of 100GHz. The highly nonlinear fiber has a nonlinear coefficient, γ of 10.8 W-1km-1 . Hence, to achieve higher FWM output power the pump power of the dual wavelength fiber laser has to be higher than that of the signal probe. The optimum measured values of pump and signal power are +13.3dBm and +5dBm respectively, limited buy the current experimental setup

Passively mode-locked fiber laser by utilizing TTG film on a D-shaped fiber as a saturable absorber

In this paper, we propose a mode-locked fiber laser by utilizing single layer Trivial Transfer Graphene film (TTGF) as a saturable absorber (SA). The SA was deposited on the top of a side-polished D-shaped fiber. The SA was then integrated in the ring cavity configuration, with a clockwise light propagation. Three distinctive 2 m erbium doped fibers (EDFs) those are Metro-Gain15 EDF, Iso-Gain6 EDF and Iso-Gain12 EDF were used as gain media, interchangeable in the experiment. From the results, the Metro-Gain15 EDF gives the most proficient gain medium on generating a passively mode-locked fiber laser. The Metro-Gain15 Erbium doped mode-locked Laser was successfully producing ultrashort pulse with 8 nm spectral band-width, 13 MHz of repetition rate and 915 fs pulse duration. These outcomes demonstrated that TTGF deposited on the D-shaped fiber is a suitable component as an SA to produce a stable output passively mode-locked fiber laser for many optical fiber applications

Passively Q-Switched pulse erbium doped fiber laser using Antimony (III) Telluride (Sb2Te3) thin film as saturable absorber

This paper demonstrates on an antimony telluride (Sb2Te3) thin film sandwiched between two fiber ferrule as saturable absorber for Qswitched pulsed Erbium doped fiber (EDF) laser. The saturable absorber is fabricated by dissolving Antimony (III) Telluride powder into PVA solution and dry in the ambient temperature for 48 hours. Then, 1 mm2 x 1 mm2 Sb2Te3-PVA film based saturable absorber is sandwiched in between FC/PC ferrule for Q-switched laser generation. The modulation depth of the Sb2Te3 is measured as 28.01% with input intensity 0.02 MW/cm2 . The developed passive saturable absorber integrated in EDF laser in ring cavity and the characterised pulse is with repetition rates of 30.21 kHz, shortest pulse width of 3.26 µs and signal-noise-ratio (SNR) of 42 dB. The maximum output pulse energy is achieved at pump power 69.5 mW with 29.5 nJ and the output power 0.89 mW

Graphite saturable absorber for Q switched fiber laser

This paper reported a successful demonstration on Q-switched fiber laser by using graphite as saturable absorber (SA). The graphite is deposited on the fiber ferrule through a simple mechanical exfoliation method. The modulation depth of the graphite SA is 19.2% with a saturation intensity of 85 MW/cm². The maximum achievable pulse repetition rates and pulse width are 42.41 kHz and 3.40 μs respec-tively. Meanwhile, its optical signal-to-noise ratio is about 50.81 dB. The Q-switched pulses have the maximum pulse energy of 5.84 nJ. These outcomes demonstrated that a stable output of passively Q-switched fiber laser is produced and can be applied for various optical fiber applications