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Energy efficiency evaluation of metal laser direct deposition based on process characteristics and empirical modeling
摘要： Metal laser direct deposition (MLDD) is a typical process in additive manufacturing (AM), which permits the build of complex and fully dense metallic parts by using laser to melt the metal powder layer by layer. However, the process is characterized by high energy consumption and low energy efficiency. This paper established an empirical model to characterize the relationship between process parameters and energy efficiency for MLDD based on the essence of thermodynamics physical energy conversion. Additionally, a recognition method of cross-sectional profile of the deposited layer was achieved by adding tungsten carbide (WC) powder, which greatly improved the measurement reliability. Taguchi experiment and regression identification method were applied, and the relative error of the model was less than 10%. The results show that laser power has significant influence on the process energy efficiency of MLDD. The energy efficiency of single-track multi-layer stacking (SMS) process and multi-track single-layer lapping (MSL) process increased by 5.7% and 50.3%, respectively, under the optimal process parameter condition. The proposed model can be used effectively for the energy efficiency evaluation and offer the potential for improving the sustainability of MLDD.
关键词： Energy efficiency,Metal laser direct deposition (MLDD),Cross-sectional profile,Taguchi experiment
更新于2025-11-28 14:24:20
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Design and optimization of grid-tied and off-grid solar PV systems for super-efficient electrical appliances
摘要： Modeling, simulation, and optimization methods are used in the present study to design grid-tied and off-grid solar PV systems for super-efficient electrical appliances for residential buildings. The principal objective of this study is to design a renewable energy system to serve the electric load of super-efficient appliances with high penetration of renewable resources and low greenhouse gas emissions and cost of energy. Hourly calculations using optimization method are used to study the daily and yearly performance and the cost of the renewable energy systems. A comparison between the performance of the grid-tied and off-grid solar PV systems using conventional and super-efficient appliances in Dubai is presented. The comparison includes the total power production from the solar PV system, the power purchased from the grid, the extra power sold to the utility grid, the power used to meet the electrical load of the appliances, the excess power, the renewable fraction, the greenhouse gas emissions, and the levelized cost of energy. The results of the simulation show that the integration of super-efficient appliances powered with the grid-tied solar power system is a good option to control the energy consumption of the residential buildings and to reduce the cost of electricity and greenhouse gas emissions: low building energy consumption (reduction by half of the electrical power consumption: from 62.91 to 30.78 kWh/day using super-efficient appliances); all the electrical power demand for the building is met without shortage; the power systems produce low excess power (0.29–1.82%) compared to the off-grid power system; all the extra power from the solar PV is sold back to the grid to reduce the cost of energy, high renewable fraction (68% of the total energy served to the load is produced from solar PV), low-cost of electricity (12% reduction of the cost of energy compared to the utility grid), and low greenhouse gas emissions (45–51% reductions of the CO2, NOX, and SO2 emissions compared to the conventional electrical appliances).
关键词： Grid-tied solar PV,Off-grid solar PV,Super-efficient appliances,Energy efficiency,Renewable energy
更新于2025-09-23 15:23:52
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Numerical investigation of energy performance and cost analysis of Moroccan’s building smart walls integrating vanadium dioxide
摘要： Thermochromic materials such as vanadium dioxide (VO2) have the capability to regulate their infrared reflectivity depending on ambient temperature. Such smart materials are attractive for applications like smart windows and smart roofs. In this paper, we investigate numerically the impact of tungsten (W) doped VO2 application as a smart outdoor wall layer on the building energy consumption in the Mediterranean climate. Temperature distributions through wall configurations with and without W doped VO2 were calculated using finite differences method implemented in Matlab environment. Calculations take into consideration dynamic variations of W doped VO2 absorptivity depending on outdoor temperature variations. Decrement factor, time lag, transmission and peak loads of cooling and heating were calculated. Results have shown that the indoor surface temperature is attenuated during summer by 2–3 °C depending on orientation. Cooling energy saving due to the use of W doped VO2 in summer is around 70% monthly which is equivalent to save $21.6/month of electricity invoiced amount. During winter, W doped VO2 maintains the same value of absorptivity as the uninsulated wall. Thus, results show small differences for indoor surface temperature and heating energy consumption. The application of W doped VO2 in intelligent thermal wall insulation offers a real-time dynamic variation of building’s envelope solar absorptivity and makes smart walls concept more feasible.
关键词： Energy efficiency,Smart wall,Radiative thermal rectification,Thermochromic,Real-time dynamic absorptivity,Vanadium dioxide
更新于2025-09-23 15:23:52
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Scalable modulation of reduced graphene oxide properties via regulating graphite oxide precursors
摘要： Here we demonstrate the scalable modulation of reduced graphene oxide (RGO) properties by regulating graphite oxide (GtO) precursors. Our findings show the thickness and loose degree of GtO precursors act as key roles in flame activation process. Interestingly, the looser GtO transforms into RGO with a lower specific surface area (SSA); RGO from the thinner GtO paper shows a higher SSA. By regulating GtO precursors, SSA from 1030.5 to 335.3 m2 g?1, defect degree, oxidation degree, and pore volume from 4.61 to 1.36 cm3 g?1 can be tuned. The corresponding structural properties are translated into unique supercapacitor (SC) performances such as high specific capacitance (the highest value of 576 F g?1) and coulombic efficiency. Additionally, this method indicates great potential to prepare RGO-based metal oxide composites with good homogeneity and good SC behaviors.
关键词： Flame,Energy efficiency,Reduced graphene oxide,Precursor,Supercapacitor
更新于2025-09-23 15:23:52
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Evaluation of Signal Regeneration Impact on the Power Efficiency of Long-Haul DWDM Systems
摘要： Due to potential economic benefits and expected environmental impact, the power consumption issue in wired networks has become a major challenge. Furthermore, continuously increasing global Internet traffic demands high spectral efficiency values. As a result, the relationship between spectral efficiency and energy consumption of telecommunication networks has become a popular topic of academic research over the past years, where a critical parameter is power efficiency. The present research contains calculation results that can be used by optical network designers and operators as guidance for developing more power efficient communication networks if the planned system falls within the scope of this paper. The research results are presented as average aggregated traffic curves that provide more flexible data for the systems with different spectrum availability. Further investigations could be needed in order to evaluate the parameters under consideration taking into account particular spectral parameters, e.g., the entire C-band.
关键词： DWDM,phase shift keying,differential phase shift keying,power consumption,spectral efficiency,sub-band spacing,WDM networks,single-line rate,optical fibre networks,power efficiency,energy efficiency
更新于2025-09-23 15:22:29
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[IEEE 2018 25th International Conference "Mixed Design of Integrated Circuits and System" (MIXDES) - Gdynia, Poland (2018.6.21-2018.6.23)] 2018 25th International Conference "Mixed Design of Integrated Circuits and System" (MIXDES) - Optimization of Class-D Amplifier Output Stage for Piezoelectric Actuator Control
摘要： Design of a piezoelectric driver for a microelectromechanical actuator in a small form factor for laser telecommunications is introduced. The driver introduces a number of challenges due to its size and power limitations as a Microelectromechanical Systems (MEMS) actuator. Because of the small form factor, the driver must be integrated into the actuator itself, which limits its size and power. The efficiency of a linear amplifier becomes a major drawback due to the dissipated heat of only 20 W for the Laser Telecommunications Module (LTM), low efficiency of a linear amplifier becomes a major drawback due to the dissipated heat. Switching Class-E amplifiers provide exceptional efficiency compared to non-switching solutions at a price of high frequency harmonics, which allows for higher output power without additional heat dissipation. The efficiency, however, comes at a price of high frequency harmonics, which must be reduced by implementing a High-Energy-Efficiency Interference (HEEI) and Total Harmonic Distortion (THD). Driving a capacitive load, such as a piezoelectric actuator, at a high frequency with a Class-E amplifier requires a matching network to achieve the desired output power. The measurements were performed on a custom-made driver model for piezoelectric stack actuators with 270 V peak-to-peak voltage, 500 kHz switching frequency and a range of capacitive load from 2.1 nF to 20 nF.
关键词： Actuator,Driver,Amplifier,Distortion,LTM.2,Output Stage,SMPS,Class-E,Total,LTM,THD,MEMS,Harmonic,Transmission,Telecommunications,Laser,Module,High-Energy-Efficiency,HEEI,Interference,Piezoelectric,Microelectromechanical
更新于2025-09-23 15:22:29
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Energy efficient Placement of Baseband Functions and Mobile Edge Computing in 5G Networks
摘要： We propose and compare different potential placement schemes for baseband functions and mobile edge computing on their energy efficiency. Simulation results show that NFV enabled flexible placement reduces more than 20% power than traditional solutions.
关键词： Mobile edge computing placement,5G optical transport,Baseband functions placement,energy efficiency
更新于2025-09-23 15:22:29
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[IEEE 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) - Sydney, Australia (2018.11.21-2018.11.23)] 2018 28th International Telecommunication Networks and Applications Conference (ITNAC) - CamThings: IoT Camera with Energy-Efficient Communication by Edge Computing based on Deep Learning
摘要： In recent years, the demand for IoT cameras has increased due to the high demand for image data. However, the image sensor is unsuitable as an energy-constrained edge device for IoT due to its high-power consumption. Therefore, periodic on–off scheduling of IoT cameras is a promising approach since video recording using image sensors is energy-intensive. Due to the constrained computing performance of edge devices, IoT is still based on cloud computing with energy leaks by transmitting all the data of edge devices to cloud. In this paper, we proposed energy-efficient communication via edge computing based on deep learning, which reduces power consumption by transmitting only images of interest classified using edge computing. We also designed and implemented CamThings, which is an energy-efficient IoT camera with periodic on–off scheduling and the proposed energy-efficient communication. To analyze and evaluate the efficiency of the proposed communication scheme, we implemented a power consumption model for CamThings. In an environment with a low interest ratio, the proposed CamThings is superior to the baseline method with only periodic on–off scheduling in terms of power consumption and lifetime. When the scheduling period T is 5s and the interest ratio is 0.1, the proposed method consumed 41% less power than the baseline method. As a result, CamThings has a lifetime of more than one month.
关键词： Wireless Communication,Energy Efficiency,Edge Computing,IoT Camera,Deep Learning
更新于2025-09-23 15:22:29
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Tuning phosphors for better white light
摘要： Light-emitting diodes (LEDs) that produce white light are about to take over the lighting world. The U.S. market share of these super-long-lasting, cool-to-the-touch lights, which use less than a quarter of the energy of conventional incandescent bulbs, sits around 10%. Industry watchers predict that number will exceed 80% by 2030, reducing power consumption in the U.S. by 40%. Chemists are taking a leading role in this technology, which underpins general lighting and electronic displays, by customizing the emission spectrum, stability, and other properties of inorganic phosphors in the LEDs that help produce finely tuned white light.
关键词： energy efficiency,inorganic phosphors,color rendering index,LEDs,white light
更新于2025-09-23 15:21:21
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Factors Having a Crutial Impact on Energy Efficiency of Floodlighitng
摘要： Floodlighting designs have only been analysed in terms of visual and aesthetic beauty up to now. Research in the field of floodlighting has also focused on other aspects of this type of lighting in recent years. The energy efficiency issue and the impact on light pollution are the most crucial aspects. These issues have not yet been properly explored in the literature. Significant factors which affect the issue of the engineering aspect of floodlighting have to be determined and studied carefully because of their high importance. The main aim of this paper is to present the key factors which have a crucial impact on energy efficiency and light pollution in the field of floodlighting. These factors are: the direction and location of the lighting equipment, luminous intensity distribution, light output ratio, the method of floodlighting and the spectral power distribution of a light source, as well as the spectral distribution of the reflectance from the illuminated surface. Each of these factors are precisely commented on. These are presented by means of a calculation, a measurement or a visualization example, which clearly allow the crux of the problem to be analysed in the easiest way. The research shows that the problem of improving floodlighting design in respect of energy efficiency and light pollution is a complex and exacting problem for a lighting designer. It definitely requires the creation of an individual and unified system of assessment. It ought to take into account all the crucial factors and be simple, understandable and easy to use. Development of such a system is underway at the Lighting Technology Division of Warsaw University of Technology. It will soon be finalized in the form of a doctoral dissertation by one of the authors of this paper.
关键词： energy efficiency,lighting technology,floodlighting utilization factor,light pollution,floodlighting
更新于2025-09-23 15:21:21