- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Parametric Analysis of High Power Disk Laser Welding of 5052-H32 Aluminium Alloy
摘要： High power disk laser conducting welding of 2 mm thick AA 5052-H32 was performed within a process window and optimized for improved weld quality (i.e. penetration depth). The macrostructure of the weldment was investigated for the weld penetration depth at varying processing parameters using stereo zoom optical microscopy. The significance of the single effects and interaction effects of the parameters on the weld penetration depth was determined using ANOVA. Maximum weld penetration depth (1.71 mm) was achieved at laser power of 2600 W, welding speed of 0.03 m/s and focal position of -3.75 mm. At 95% confidence, only the welding speed –focal position interaction was found to contribute significantly to the weld penetration depth. The effect of the welding speed was most noticeable at low focal position (F < -3.9), that is, when the workpiece is further away from the focus. A linear regression mathematical model predicting the penetration depth of AA 5052-H32 disk laser weldments to an accuracy of 86% was developed and validated.
关键词： AA 5052-H32 Aluminium Alloy,Optimisation,Regression Model,Disk Laser Welding,ANOVA,Penetration Depth
更新于2025-09-16 10:30:52
-
Optimisation of laser welding parameters for incoloy 800HT joints using Grey-fuzzy Taguchi approach
摘要： The present study attempts to find the optimal level of parameters for multi performance characteristics in laser welding of incoloy 800HT using Grey-Fuzzy algorithm. Incoloy 800HT, which comes under the family of austenitic nickel-chromium-based super alloys exhibits good strength, excellent resistance to carburization and oxidation in high-temperature exposure. This alloy has been considered as a prominent material for fourth generation nuclear power plants. Laser welding has proved to be advantageous due to its characteristics such as narrow fusion zone, low heat input, concentrated heat intensity and the ability to align the beam to a specific position with respect to joint line. Taguchi L9 experiment was used to perform laser welding on incoloy 800HT. The input parameters chosen were the welding speed, focal position and laser power. The output performance characteristics were the hardness, toughness and ultimate tensile strength. To improve the quality of the weld, the optimal combination of laser welding parameters was chosen using grey relational analysis and grey fuzzy logic approach offers improved Grey-Fuzzy reasoning grade and has less uncertainties when compared with grey relational technique. Analysis of variance (ANOVA) was used to find percentage contribution of the laser welding parameters and found that welding speed was the most influential factor in welding of incoloy 800HT.
关键词： laser welding,grey-fuzzy,optimisation
更新于2025-09-16 10:30:52
-
Evaluation and optimisation of the SSAIL method for laser-assisted selective electroless copper deposition on dielectrics
摘要： Formation of electrical circuit traces on 3D shaped dielectrics is one of the biggest challenges in 3D Microscopic Integrated Devices (3D-MID). We have developed a new method called “Selective Surface Activation Induced by a Laser” (SSAIL), which is a promising technology for solving emerged production issues for electrical conductors on polymers. SSAIL contains 3 main steps: laser modification of the dielectric surface, chemical activation of the modified areas and electroless plating of the activated parts. In this paper, the route and results on optimisation of the SSAIL process by evaluating properties of the final metal-plated traces are provided. A special validation method of the technology based on the quality and reliability of the plating has been proposed. The sheet resistance, adhesion strength to the substrate and spatial selectivity of plated copper were used to find the optimal laser processing parameters.
关键词： Selective electroless plating,Laser activation,Moulded interconnect devices,Polymer,Electric circuit,Evaluation and optimisation
更新于2025-09-16 10:30:52
-
Determination of economically optimised building integrated photovoltaic systems for utilisation on facades in the tropical climate: A case study of Colombo, Sri Lanka
摘要： Building integrated photovoltaics (BIPV) are becoming a viable solution for clean on-site energy production and utilisation to combat the existing energy crisis. In tropical climates, although rooftops are ideal for photovoltaic (PV) module integration, the available area may be insufficient to meet building energy demand due to the recent high-rise nature of urban buildings, causing a requirement for the utilisation of facades. However, the high angle of solar elevation means that facades are unfavourably oriented towards receiving incident solar irradiation. In addition, the issue exists of high solar heat gains into built spaces. This paper proposes a method to utilise horizontally inclined photovoltaic modules integrated on solar shading devices in order to combat these issues of unfavourable inclination and solar heat gains in commercial office buildings in Colombo, Sri Lanka. Various strategies are introduced and evaluated in terms of their inclination angles and the distance between installations. The results are analysed in terms of economic potential in order to determine which strategies are capable of producing the most electricity and reducing building cooling loads for the lowest installation costs. The results show that horizontal inclinations of PV on facades are capable of generating nearly 8% more electricity as a percentage of the building energy consumption when compared with traditional vertical PV facade installations.
关键词： facades,office building,photovoltaic integrated shading systems,building integrated photovoltaics,optimisation
更新于2025-09-16 10:30:52
-
Integrative modelling and optimisation of a desiccant cooling system coupled with a photovoltaic thermal-solar air heater
摘要： An integrated model of a desiccant cooling system with a hybrid photovoltaic thermal collector-solar air heater (PVT-SAH) was developed and coupled with a building model to enable a performance evaluation and optimisation of the system. A double pass PVT-SAH system that incorporates heat pipes was used to increase the air temperature of the PVT-SAH outlet in order to regenerate the desiccant in a desiccant wheel. The integrated model was then used to quantify the performance of the hybrid desiccant cooling system in terms of Solar Fraction (SF) and the Coe?cient of Performance (COP) and its response to the various sizes of PVT-SAH systems. The model outputs showed that the selection of the PVT-SAH design parameters can be critical in improving the system’s utilisation in a desiccant cooling process. For a commercial building case study in a hot and humid climate, the annual Solar Fraction and the electrical COP of the cooling system reached up to 96.6% and up to 19.8 respectively, when the design of the PVT-SAH was optimised. The optimal electrical COP was higher than those for non-optimal designs that ranged from 0.6 to 15.1. The minimum size of the PVT-SAH that is required for the hybrid desiccant cooling system to exceed a typical COP for commercial buildings (2.6–3.0) was found to be 0.35 m2 per m2 of the conditioned ?oor area.
关键词： Desiccant cooling system,Integrated modelling of solar desiccant systems,Photovoltaic thermal collector-solar air heater,Design optimisation
更新于2025-09-12 10:27:22
-
Particle swarm optimisation-based model and analysis of photovoltaic module characteristics in snowy conditions
摘要： In this study, a novel methodology of photovoltaic (PV) modelling is proposed to represent the instantaneous electrical characteristics of PV modules covered with snow. The attenuation of the transmitted solar radiation penetrating a layer of snow is rigorously estimated based on the Giddings and LaChapelle theory. This theory introduced the level of radiation that reaches the surface of the PV module through the snowpack, significantly affected by the snow properties and thickness. The proposed modelling approach is based on the single-diode-five-parameter equivalent circuit model. The parameters of the model are updated through instantaneous measurements of voltage and current that are optimised by the particle swarm optimisation algorithm. The proposed approach for modelling snow-covered PV modules was successfully validated in outdoor tests using three different types of PV module technologies typically used in North America's PV farms under different cold weather conditions. In addition, the validity of the proposed model was investigated using real data obtained from the SCADA system of a 12-MW grid-connected PV farm. The proposed model can help to improve PV performance under snow conditions and can be considered a powerful tool for the design and selection of PV modules subjected to snow accretion.
关键词： photovoltaic,Giddings and LaChapelle theory,solar radiation,PV modelling,particle swarm optimisation,SCADA system,snow conditions
更新于2025-09-11 14:15:04
-
Effects of Gas-Phase Conditions and Particle Size on the Properties of Cu(111)-Supported Zn <sub/>y</sub> O <sub/>x</sub> Particles Revealed by Global Optimisation and Ab Initio Thermodynamics
摘要： The characterisation of the interaction between nano- or sub-nano- particles with a support nowadays increasingly relies on computational modelling by means of the density functional theory calculations. These provide valuable atomic-detail understanding of the structure and energetics of supported clusters, but it is still challenging to find (or design) structural models that are representative of real systems in terms of size, structure, and composition. In this study, we have applied an extensive and systematic approach combining global optimisation based on an evolutionary algorithm with atomistic ab initio thermodynamics for finding stable structures of a relevant material for catalytic methanol synthesis: Cu(111)-supported ZnyOx clusters. We identify the ZnO3 motif as the elementary building block of such clusters, on which we recently have investigated the full catalytic process for methanol synthesis. With the collection of global minima of Cu(111)-supported ZnyOx clusters resulting from this large-scale global optimisation effort, we assess the effect of size, gas-phase conditions, and support interactions on the phase diagrams, reactivity, and structural properties of the ZnyOx particles. We find moderate size-effects that are mostly related to the differences in stable Zn:O ratios of the identified global minima and to the formation of different sites in larger clusters. In contrast, large differences in the oxidation state of the clusters as defined by the gas-phase conditions significantly affect the geometry, electronic structure, and reactivity of the ZnyOx particles. This highlights the importance of thoroughly sampling structures with different stoichiometry and appropriately assessing their stability using a detailed thermodynamics analysis.
关键词： global optimisation,Cu(111)-supported ZnyOx clusters,ab initio thermodynamics,density functional theory,methanol synthesis
更新于2025-09-11 14:15:04
-
An inverse approach to the characterisation of material parameters of piezoelectric discs with triple-ring-electrodes
摘要： For its usage in simulation-based design processes a precise knowledge of the employed material properties is inevitable. In the case of piezoelectric ceramics, the provided material parameters often suffer from large uncertainties and even inconsistencies since the standardised measurement procedure needs several specimens to determine a single set of material parameters. In contrast, the presented measurement set-up allows to calculate material parameters using one unique disc-shaped specimen with an optimised electrode topology. Using an inverse problem approach, fitting material parameters can be found using an optimisation procedure.
关键词： piezoelectric ceramics,Parameter identification,optimisation,inverse problem
更新于2025-09-10 09:29:36
-
[IEEE 2018 XIII International Conference on Electrical Machines (ICEM) - Alexandroupoli, Greece (2018.9.3-2018.9.6)] 2018 XIII International Conference on Electrical Machines (ICEM) - Optimisation of Permanent Magnet Machine Topologies Suitable for Solar Powered Aircraft
摘要： Electrification of aircraft has become a hot topic in recent years both in civil aviation and unmanned aerial vehicles. The latter domain is gaining in popularity for its high altitude applications, particularly for bringing widespread internet coverage. This paper presents the work done on the optimisation of different types and topologies of permanent magnet electrical machines that can be considered as the main contenders for such application. These topologies consist of both laminated steel core and airgap winding machines. Instead of copper, compressed aluminium windings were considered which will help in reducing the overall mass of the stator. All the topologies were simulated both under take-off and cruise condition. Each machine had to fulfil a certain thermal constraint (current density) before being simulated at cruise condition in order to find the objective function of the final design. The best topology was chosen based on high efficiency in cruise condition with reduced mass.
关键词： laminated steel machines,optimisation,Unmanned air vehicles,Electrical machines,Compressed Aluminium windings,Airgap winding machines,Halbach Array
更新于2025-09-10 09:29:36
-
[IEEE 2018 International Conference On Advances in Communication and Computing Technology (ICACCT) - Sangamner, India (2018.2.8-2018.2.9)] 2018 International Conference On Advances in Communication and Computing Technology (ICACCT) - An Analysis of Wavelet Based Dual Digital Image Watermarking Using SVD
摘要： Intellectual properties are being obtained and reproduced easily. This raises a serious question on the ownership of images. Hence content owners and service providers seek protection of digital multimedia through watermarking. Though watermark is inserted in host image it becomes difficult to prove ownership due to various attacks affecting the image. Hence watermarking should be as robust as possible maintaining the fidelity. As wavelet based image watermarking resembles the human visual system, it is gaining vital importance in protecting copyright information. In this paper a hybrid scheme based on DWT and SVD is implemented. Two watermarks are inserted in host image one by one. After decomposing the primary watermark image into four bands, SVD is applied to each band, and the same secondary watermark is embedded by modifying the singular values. In this way new watermark is generated which is then embedded into host image. Analysis of the method is done after performing different attacks such as rotation, addition of Gaussian and Poisson noise, average filtering etc. on the watermarked host image. The paper also implements dual image watermarking schemes based on DWT and SVD separately. Correlation coefficient of extracted secondary watermark is 0.23481 in SVD based technique whereas in DWT based technique it is 0.74443 for Gaussian noise attack. On the other hand for DWT-SVD based method it is 0.88701. Thus performance of combined DWT-SVD dual image watermarking is proven optimised in comparison with the previously mentioned two methods.
关键词： singular value decomposition,optimisation technique,correlation coefficient,robustness,discrete wavelet transform,Watermark
更新于2025-09-10 09:29:36