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20?W 1952?nm tandem hybrid single and double clad TDFA
摘要： A simple engineering design is important for achieving high Thulium-doped ampli?er (TDFA) performance such as good power conversion, low noise ?gure (NF), scalable output power, high gain, and stable operation over a large dynamic range. In this paper we report the design, performance, and simulation of two stage high-power 1952 nm hybrid single and double clad TDFAs. The ?rst stage of our hybrid ampli?er is a single clad design, and the second stage is a double clad design. We demonstrate TDFAs with an output power greater than 20 W with single-frequency narrow linewidth (i.e. MHz) input signals at both 1952 and 2004 nm. An optical 10 dB bandwidth of 80 nm is derived from the ASE spectrum. The power stage is constructed with 10 μm core active ?bers showing a maximum optical slope e?ciency greater than 50%. The experimental results lead to a 1 dB agreement with our simulation tool developed for single clad and double clad TDFAs. Overall this hybrid ampli?er o?ers versatile features with the potential of much higher output power.
关键词： Simulation,Fiber ampli?er,Multistage,Single frequency,Fiber measurement,Thulium
更新于2025-09-23 15:23:52
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Effect of multi stage abrasive slurry jet polishing on surface generation in glass
摘要： The polishing process is used to produce a smooth surface with a required geometrical figure for the optical component. The abrasive slurry jet polishing process is one of the non-traditional polishing process, which is used to polish freeform optics with the nano-level surface finish. In the abrasive slurry jet polishing process, the saturation in surface roughness is observed with a jet exposure time or polishing time. Once the saturation limit is reached a further reduction in surface roughness without the modification of processing conditions and the size of the abrasive particles is not possible. Hence to achieve the required surface roughness a different polishing strategy has to be adapted. In this work, an attempt was carried out to yield a considerable reduction in surface roughness using a multistage polishing concept. In this concept, the impact angle, the traverse speed of the nozzle, the type and size of the abrasive particle were changed after the first stage of polishing. The surface generation has been studied by measuring the surface roughness at each stage of polishing, and the Scanning Electron Microscope (SEM) analyses have been done to understand the changes in surface texture, after polishing. From the experiments, the large size Al2O3 particle in the first stage of polishing and then small size Al2O3 particle in the remaining stages of polishing yields a considerable reduction in surface roughness. The combination of parameters with the type and size of the abrasive particles to be used to achieve the required surface characteristics were demonstrated. Thus, the multistage polishing concept can be floated as a viable strategy to achieve a high reduction in surface roughness on the optical component.
关键词： Abrasive,Particle size,Traverse speed,Slurry,Multistage Polishing,Glass
更新于2025-09-23 15:23:52
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[Energy, Environment, and Sustainability] Advances in Solar Energy Research || Application of Nanofluid-Based Direct Absorption Solar Collector in Once-Through Multistage Flash Desalination System
摘要： Multistage ?ash (MSF) desalination technique is one of the simplest of thermal desalination methods which requires thermal energy in order to desalinate seawater. This thermal energy can be provided by solar energy harnessed by a direct absorption solar collector (DASC) in which a nano?uid while ?owing through the collector absorbs the incident irradiation directly and gets heated to higher temperatures. These collectors are having a relatively higher thermal ef?ciency (10% higher) as compared to conventional surface-absorption-based solar collectors. In this study, a direct absorption solar collector (DASC) has been used as a heat source for multistage ?ash (MSF) desalination system having once-through (OT) con?guration, and these two systems are coupled using a counter?ow type heat exchanger. This direct absorption collector is replaced by surface-absorption-based collector in order to prevent the degradation of thermal performance of surface-absorption-based collector due to high salinity of seawater as in the present case seawater ?ows through heat exchanger and is getting heated by the nano?uid ?owing through direct absorption collector. The aim of the present study is to evaluate the thermal performance of the combined system which is represented by a quantity known as gained output ratio (GOR). The thermal performance or ef?ciency of the solar collector depends upon various parameters such as thickness of nano?uid layer inside DASC (H), length of the collector (L), particle volume fraction of nanoparticles (fv), and incident solar energy (q) which will affect the performance of the MSF system also. Hence, the performance of the combined system will be evaluated as a function of the collector parameters mentioned above. The gained output ratio is also evaluated as a function of brine rejection temperature (Tb) and feed seawater temperature (Tf) which are parameters associated with the MSF desalination system. The fresh water production rate (m?d) has also been evaluated as a function of the abovementioned parameters related to the collector and MSF system. A numerical model has been prepared to solve the temperature pro?le of the DASC system which is solved using ?nite difference implicit method (FDM) with the help of MATLAB. The numerical model for MSF desalination system is also prepared and solved in MATLAB.
关键词： Nano?uid,Once-through,Solar energy,Desalination,Multistage ?ash
更新于2025-09-23 15:21:01
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - A High Precision Multi-Ratio Three-Stage Current Transformer (CT) for Loss Measurements of Extra High Voltage (EHV) Three-Phase Shunt Reactors with Test Voltages up to 1100 kV
摘要： An overview of the development and performance of special high precision multi-ratio three-stage CT and its application for loss measurement of EHV three-phase shunt reactors with AC test voltages up to 1100 kV at Royal SMIT Transformers are presented and discuss. It features current ratios of 500A/1A, 400A/1A, 300A/1A, 200A/1A, and 100A/1A with ratio errors within 3×10-6 in both magnitude and phase with burdens up to 1.0 ? and at power frequencies of 50 Hz - 60 Hz.
关键词： multi-ratio,ratio errors,multistage,Extra High Voltage (EHV),loss measurements,uncertainty,shunt reactor,three-stage,precision measurements
更新于2025-09-10 09:29:36
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Development of a Radial Pulse Monitoring System Based on a Graphene-Coated Fiber
摘要： The radial pulse is considered as a fundamental indicator for the diagnosis of cardiovascular diseases, which can guide therapeutic decisions in complex clinical situations. We designed and fabricated a real-time low-cost wearable pulse monitoring system based on a graphene-coated fiber to detect the radial pulse. The graphene-coated fiber, acting as sensing component, had excellent conductance property and high sensitivity. However, the amplitude of the pulse is subtle, always masked by noise. As a consequence, a diminutive signal conditioning unit integrated a low-noise instrument amplifier was developed to enhance the signals. Furtherly, we proposed a newly multistage filter method to attenuate the noise synchronously. The signal noise ratio was improved by at least 27dB, compared with traditional measurement method. Meanwhile, a graphical user interface was developed to monitor the pulses in real time, making the monitor convenient and timely. The heart rate, which is of clinical significance, was measured accurately. The data was being stored in the PC terminal simultaneously to obtain an overall heart health and fitness level. The superior sensing performance and economic fabrication process of the pulse monitoring system strengthen our confidence in the application of the smart fabrics in wearable sensing and home health care fields.
关键词： graphene-coated fiber,signal noise ratio,heart rate,pulse monitoring system,economic fabrication process,multistage filter method,radial pulse
更新于2025-09-10 09:29:36
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5?W 1952?nm Brillouin-free efficient single clad TDFA
摘要： We report the performance of a two stage single clad (SC) Thulium-doped fiber amplifier (TDFA), delivering an output power of 5 W at 1952 nm without stimulated Brillouin scattering (SBS) for a single-frequency input signal. A slope efficiency greater than 60%, a signal gain greater than 60 dB and an input dynamic range > 30 dB were achieved. The amplifier topology was optimized with a simulation tool, experimental results and simulations are in good agreement.
关键词： Multistage,Single-frequency,Brillouin,Single clad,Fiber amplifier,Simulation,Thulium
更新于2025-09-04 15:30:14