We investigated multiwavelength fiber laser (MWFL) performance using different types of semiconductor optical amplifiers (SOAs) utilizing Lyot filter as comb filter. The lasing performances of linear SOA (LSOA), nonlinear SOA (NLSOA) and booster optical amplifier (BOA) at different current settings were observed. Among the three SOAs, LSOA has the best lasing performance due to the lowest peak power difference with the highest number of lasing lines, a high ER value of 42 dB and considerable high peak power of -14.1 dBm at 550 mA. The multiwavelength laser is stable within 60 minutes at power fluctuation of less than 0.2 dB. The output spectra at 550 mA for all the SOAs are 70 nm to 80 nm wavelength difference from the ASE spectra.
IntroductionAn efficient water distribution system relies on a good water pipeline system. Water pipeline leakages are one of a few challenges to the water utility companies all over the world in providing the service. Several factors have been identified contributed to the water pipeline leakages such as ageing infrastructure, severe environmental conditions and third-party damages [1]. A recent report published by World Bank in 2016 indicates there is 45 billion cubic meters of water loss in that year. From a financial point of view this huge amount of losses is equivalent to a value of USD 3 billion whilst from a social point of view it can supply water to 90 million people in a year [2]. During pipeline leakage, a portion of the water delivered within the water distribution network wasted and this affects the Non-Revenue Water (NRW) efficiency to the water utility company. NRW is the lowest hanging fruits to improve water utility efficiency [3]. Minimizing the NRW is one of the challenges encountered by the water utility company because the uncontrolled NRW can cause vicious cycle [4]. Researchers in [5] studied the detail of pipeline leakages and emphasized that there are two main factors that affecting to the NRW efficiency; apparent losses and real losses. The apparent losses were due to meter defect, illegal tapping, water storage tank maintenance, fire brigade use and others. The real losses were due to a pipe burst, pipe leakages and water overflow due to faulty valves. A statistic from [4] in 2008 exhibits that real losses accounted for 61.5% of total water loss recorded. Hence there is an urgency to detect the pipeline leakage and localize it in the shortest time with leak location accuracy is the main benchmark.Pipeline leakage incidents sometimes go unnoticed until the symptoms are visible such as low water pressure or water supply interruptions. This happens when the water pipeline is located underground or far away from the community area. Even though the leakages is visible and noticed, it still takes time to the relevant authorities to locate the leak location. This issue has gained an interest in a lot of researchers and in the past few decades, numerous studies and research have been conducted to solve or at least minimize this issue. The research area in the field of localization can be partitioned into two categories; the external and internal system. The external system refers to the hardware-based such Abstract: Pipeline leakages in water distribution network (WDN) is one of the prominent issues that has gain an interest among researchers in the past few years. Time and accuracy play an important role in leak localization as it has huge impact to the human population and economic point of view. The complexity of WDN has prompt numerous techniques and methods been introduced focusing on the accuracy and efficacy. In general, localization techniques can be divided into two broad categories; external and internal systems. This paper reviews some of the techniques that has been explored and pr...
IntroductionAn efficient water distribution system relies on a good water pipeline system. Water pipeline leakages are one of a few challenges to the water utility companies all over the world in providing the service. Several factors have been identified contributed to the water pipeline leakages such as ageing infrastructure, severe environmental conditions and third-party damages [1]. A recent report published by World Bank in 2016 indicates there is 45 billion cubic meters of water loss in that year. From a financial point of view this huge amount of losses is equivalent to a value of USD 3 billion whilst from a social point of view it can supply water to 90 million people in a year [2]. During pipeline leakage, a portion of the water delivered within the water distribution network wasted and this affects the Non-Revenue Water (NRW) efficiency to the water utility company. NRW is the lowest hanging fruits to improve water utility efficiency [3]. Minimizing the NRW is one of the challenges encountered by the water utility company because the uncontrolled NRW can cause vicious cycle [4]. Researchers in [5] studied the detail of pipeline leakages and emphasized that there are two main factors that affecting to the NRW efficiency; apparent losses and real losses. The apparent losses were due to meter defect, illegal tapping, water storage tank maintenance, fire brigade use and others. The real losses were due to a pipe burst, pipe leakages and water overflow due to faulty valves. A statistic from [4] in 2008 exhibits that real losses accounted for 61.5% of total water loss recorded. Hence there is an urgency to detect the pipeline leakage and localize it in the shortest time with leak location accuracy is the main benchmark.Pipeline leakage incidents sometimes go unnoticed until the symptoms are visible such as low water pressure or water supply interruptions. This happens when the water pipeline is located underground or far away from the community area. Even though the leakages is visible and noticed, it still takes time to the relevant authorities to locate the leak location. This issue has gained an interest in a lot of researchers and in the past few decades, numerous studies and research have been conducted to solve or at least minimize this issue. The research area in the field of localization can be partitioned into two categories; the external and internal system. The external system refers to the hardware-based such Abstract: Pipeline leakages in water distribution network (WDN) is one of the prominent issues that has gain an interest among researchers in the past few years. Time and accuracy play an important role in leak localization as it has huge impact to the human population and economic point of view. The complexity of WDN has prompt numerous techniques and methods been introduced focusing on the accuracy and efficacy. In general, localization techniques can be divided into two broad categories; external and internal systems. This paper reviews some of the techniques that has been explored and pr...
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