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The color of transformer oil can be one of the first indicators determining the quality of the transformer oil and the condition of the power transformer. The current method of determining the color index (CI) of transformer oil utilizes a color comparator based on the American Society for Testing and Materials (ASTM) D1500 standard, which requires a human observer, leading to human error and a limited number of samples tested per day. This paper reports on the utilization of ultra violet-blue laser at 405- and 450-nm wavelengths to measure the CI of transformer oil. In total, 20 transformer oil samples with CI ranging from 0.5 to 7.5 were measured at optical pathlengths of 10 and 1 mm. A linear regression model was developed to determine the color index of the transformer oil. The equation was validated and verified by measuring the output power of a new batch of transformer oil samples. Data obtained from the measurements were able to quantify the CI accurately with root-mean-square errors (RMSEs) of 0.2229 for 405 nm and 0.4129 for 450 nm. This approach shows the commercialization potential of a low-cost portable device that can be used on-site for the monitoring of power transformers.

For most natural or naturally derived liquid products, their colour reflects on their quality and occasionally affects customer preferences. To date, there are a few subjective and objective methods for colour measurement which are currently utilized by various industries. Researchers are also improving these methods and inventing new methods, as colour is proven to have the ability to provide various information on the condition and quality of the liquid. However, a review on the methods, especially for amber-coloured liquid, has not been conducted yet. This paper presents a comprehensive review on the subjective and objective methods for colour measurement of amber-coloured liquids. The pros and cons of the measurement methods, the effects of the colour on customer preferences, and the international industry standards on colour measurements are reviewed and discussed. In addition, this study elaborates on the issues and challenges related to the colour measurement techniques as well as recommendations for future research. This review demonstrates that the existing colour measurement technique can determine the colour according to the standards and colour scales. However, the efforts toward minimizing the complexity of the hardware while maximizing the signal processing through advanced computation are still lacking. Therefore, through this critical review, this review can hopefully intensify the efforts toward finding an optimized method or technique for colour measurement of liquids and thus expedite the development of a portable device that can measure colour accurately.

We demonstrated a multiwavelength performance based on bidirectional Lyot filter at different temperature of polarization maintaining fiber (PMF) and semiconductor optical amplifiers (SOAs). The multiwavelength fiber laser (MWFL) based on bidirectional Lyot filter is not investigated thoroughly on its channel spacing tunability due to birefringence change. A channel spacing of this MWFL is tunable due to birefringence change of the PMF. The birefringence value of is changed by heating the PMF, that leads to narrower channel spacing. From the experimental data, the temperature coefficient based on PMF length of 53.2 m and 10.6 m is 0.49 ×10-3 nm/°C and 1.35 ×10-3 nm/°C, respectively, thus shorter PMF is more sensitive to temperature. We also investigated the multiwavelength performance at different SOAs. When the SOA from Qphotonics is changed to the SOA from Alphion, the extinction ratio is reduced from 15 dB to 8 dB. In terms of flatness value, the Qhotonics’s SOA has a flatter multiwavelength spectrum with only 1 dB of peak power difference from 1538 nm until 1541 nm as compared to 2.5 dB when using Alphion’s SOA.

We investigate an intensity influence towards the flatness of multiwavelength fiber laser (MWFL) based on intensity dependent transmission (IDT) mechanism. The intensity is varied by changing semiconductor optical amplifier (SOA) current and throughput port ratio. Owing to the IDT mechanism, the multiwavelength flatness is degraded with the increment of SOA current. The change of throughput port ratio of optical splitter from 10% to 90% has also affected a worse multiwavelength flatness. The flattest multiwavelength spectrum is achieved at SOA current and throughput port of 150 mA and 10%, respectively, with the lasing lines are counted up to 300 channels within 3 dB uniformity.

A channel spacing tunability of multiwavelength fiber laser (MWFL) based on bidirectional Lyot filter and semiconductor optical amplifier (SOA) is demonstrated. The birefringence value of polarization maintaining fiber (PMF) is temperature dependence, thus by heating the PMF, the channel spacing is narrower. From the experimental data, the temperature coefficient based on PMF length of 53.2 m and 10.6 m is 0.49 ×10-3 nm/°C and 1.35 ×10-3 nm/°C, respectively, thus shorter PMF is more sensitive to temperature.

We demonstrate compact architecture of multiwavelength L-band Brillouin-Erbium fiber laser in a Fabry-Perot resonator. The laser architecture utilizes a double-pass Brillouin pump pre-amplification technique to increase the Brillouin gain efficiency. The proposed fiber laser structure is able to operate at shot length of single mode fiber and is able to produce high number of output channels with high peak output power. We are able to generate up to 13 and 25 output channels with a constant wavelength separation of 0.089 nm in a short single mode fiber of 0.1 km and 0.5 km respectively.

Enhancement of Brillouin gain efficiency in a multiwavelength L-band Brillouin-erbium comb fiber laser is presented. In this laser architecture, bi-directional amplification of the injected Brillouin pump signal within the erbium gain medium, before entering the single-mode fiber was utilized. Owing to this bi-directional pre-amplification of the Brillouin pump power, the requirement of a long single-mode fiber to increase the Brillouin gain efficiency was overcome. The shot length of a single-mode fiber was utilized to achieve a high number of output channels with high peak power. Up to 25 output channels with a constant wavelength separation of 0.089 nm were achieved at 170 mW of 1480 nm pump power and 0.54 mW of Brillouin pump power in a 0.5 km short single-mode fiber.

This paper describes a preliminary study on wireless sensor network (WSN) routing protocol algorithm with focus on energy saving strategy.Efficient energy saving and consumption will ensure the lifespan of the battery are prolonged and the delay of transmitting data will be within the acceptable range of 300 meter by 300 meter network size.The routing protocol Ad-hoc On Demand Distance Vector (AODV), Destination Sequence Distance Vector (DSDV) and Energy Efficient Destination Sequence Distance Vector (EE-DSDV) were used in the study to compare the performance of the network in terms of maximum delay, throughput receive as well as the remaining energy in the network.

The paper discussed on experimental result that improve the transmission distance by use of an integrated dispersion compensated double-pass erbium-doped fiber amplifier (DPC-EDFA). The chromatic dispersion compensation is achieved using chirped fiber Bragg grating as part of the EDFA design. The eye-pattern, eye-opening and timing jitter obtained using this technique shows an improvement equivalent to the distance of about 50km compared with the conventional double-pass EDFA (DP-EDFA).

A new double-pass erbium-doped fiber amplifier (DP-EDFA) using chirped fiber Bragg grating (CFBG) is reported here showing a gain of 53.4 dB and noise figure (NF) of 5.36 dB. The proposed amplifier at the same time provides dispersion compensation through the use of CFBG.