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Geometric parameters effect of the atomic force microscopy smart piezoelectric cantilever on the different rough surface topography quality by considering the capillary force
摘要： Nowadays, the atomic force microscopy (AFM) is widely used in the nanotechnology as a powerful nano-robot. The surface topography in Nanoscale is by far one of the most important usages of the AFM device. Hence, in this article, the vibration motion of a piezoelectric rectangular cross-section micro-cantilever (MC) which oscillates in the moist environment has been examined based on the Timoshenko beam theory. After extracting the MC governing equations according to Hamilton's principle, the finite element method has been used to discretize the motion equations. The surface topography has been simulated for various roughness forms in the tapping and non-contact modes by considering the effects of the Van der Waals, capillary and contact forces. Also, the experimental results obtained from the glass surface topography have been simulated. The results illustrate that the time delay in higher natural frequencies in the tapping mode is shorter in comparison with the non-contact mode, especially, for the lower natural frequencies. The sensitivity analysis of the natural frequencies, topography depth and time delay have been simulated. Results indicate that the most effective parameter is the MC length. In the first mode, the first section length has the highest effect on the surface topography time delay, also, in the second vibration mode; the most effective parameter on the time delay is the MC tip length based on the simulation results.
关键词： AFM piezoelectric micro-cantilever,Timoshenko beam,sensitivity analysis,finite element method,topography depth
更新于2025-09-23 15:23:52
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Lightweight Design of Multi-Objective Topology for a Large-Aperture Space Mirror
摘要： For a large-aperture space telescope, one of the key techniques is the method for designing the lightweight primary mirror assembly (PMA). In order to minimize the mirror surface error under axial gravity, lateral gravity, and polishing pressure at the same time, a method for topology optimization with multi-objective function combined with parametric optimization is introduced in this paper. The weighted compliance minimum is selected as the objective function to maximum the mirror structural stiffness. Then sensitivity analysis method and size optimization are used to determine the mirror structure parameters. Compared with two types of commonly used lightweight configurations, the new configuration design shows obvious superiority. In addition, the surface figure root mean square (RMS) of the mirror mounted by given bipod flexure (BF) under 1 g lateral gravity is minimized only with a value of 3.58 nm, which proves the effectiveness of the design method proposed in this paper.
关键词： lightweight structure,space mirror,multi-objective topology optimization,sensitivity analysis
更新于2025-09-23 15:23:52
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Simulation-Based Sensitivity Analysis of Conduction and Switching Losses for Silicon Carbide Power MOSFETs
摘要： The behavior of silicon carbide power MOSFETs is analyzed using TCAD device simulations with respect to conduction and switching losses. Device designs with varying breakdown voltages are simulated. The contributions to the on-state resistance are shown at room and elevated temperature. Whereas channel and substrate resistance dominate at low breakdown voltages, drift and JFET resistance dominate at high breakdown voltages. With increasing temperature, the channel resistance decreases and thus the drift resistance is the main contributor already at medium breakdown voltages. Manufacturing processes of a device can have a high influence on its losses. Variations in interface mobility, drift doping, and p-body doping can lead to a significant change of on-resistance, internal capacitances, and reverse recovery charge. For higher voltage classes the drift layer properties should be of major interest as it influences on-resistance and reverse recovery charge.
关键词： SiC power MOSFET,TCAD device simulation,sensitivity analysis,losses
更新于2025-09-23 15:23:52
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Assessment of red-edge vegetation indices for crop leaf area index estimation
摘要： This study explores the potential of vegetation indices (VIs) for crop leaf area index (LAI) estimation, with a focus on comparing red-edge reflectance based (RE-based) and the visible reflectance based (VIS-based) VIs. Seven VIs were derived from multi-temporal RapidEye images to correlate with LAI of two crop species having contrasting leaf structures and canopy architectures: spring wheat (a monocot) and canola (a dicot) in northern Ontario, Canada. The relationship between LAI and the selected VIs (LAI-VI) was characterized using a semi-empirical model. The Markov Chain Monte Carlo (MCMC) sampling method was used to estimate the model parameters, including the extinction coefficient (KVI) and VI value for dense green canopy (VI∞). Results showed that crop-specific regression models were much closer to a generic regression model using the RE-based VIs than using the VIS-based VIs. Furthermore, the joint posterior probability distribution of the KVI and VI∞ of the RE-based VIs tended to converge for the two crops. This suggests that the RE-based VIs are not as sensitive to canopy structure, e.g., the average leaf angle (ALA), as the VIS-based VIs. This is also demonstrated by the sensitivity analyses using both PROSAIL simulations and field measurements. Hence, the RE-based VIs can be used to develop a more generic LAI estimation algorithm for different crops. Further studies are required to assess the impact of soil reflectance and other factors, such as illumination-target-viewing geometries and atmospheric conditions, on LAI retrieval.
关键词： Sensitivity analysis,Crops,RapidEye,Leaf area index,red-edge,Vegetation index
更新于2025-09-23 15:23:52
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Assessing the sustainability of emerging technologies: A probabilistic LCA method applied to advanced photovoltaics
摘要： A key source of uncertainty in the environmental assessment of emerging technologies is the unpredictable manufacturing, use, and end-of-life pathways a technology can take as it progresses from lab to industrial scale. This uncertainty has sometimes been addressed in life cycle assessment (LCA) by performing scenario analysis. However, the scenario-based approach can be misleading if the probabilities of occurrence of each scenario are not incorporated. It also brings about a practical problem; considering all possible pathways, the number of scenarios can quickly become unmanageable. We present a modelling approach in which all possible pathways are modelled as a single product system with uncertain processes. These processes may or may not be selected once the technology reaches industrial scale according to given probabilities. An uncertainty analysis of such a system provides a single probability distribution for each impact score. This distribution accounts for uncertainty about the product system’s final configuration along with other sources of uncertainty. Furthermore, a global sensitivity analysis can identify whether the future selection of certain pathways over others will be of importance for the variance of the impact score. We illustrate the method with a case study of an emerging technology for front-side metallization of photovoltaic cells.
关键词： sustainability assessment,LCA,uncertainty,global sensitivity analysis,Life cycle assessment,emerging technologies
更新于2025-09-19 17:13:59
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Brent’s algorithm based new computational approach for accurate determination of single-diode model parameters to simulate solar cells and modules
摘要： Simulated current-voltage (I-V) characteristics of photovoltaic (PV) cells and modules are significant for the performance assessment, design and quality control, which are decided by the accurate determination of the intrinsic parameters of the devices. Commonly, a single-diode model is utilized to extract these parameters such as the ideality factor (n), series resistance (Rs), shunt resistance (Rsh), saturation current (Io) and photo-generated current (Iλ). Driven by this idea, a new mathematical manipulation was performed on the single-diode equation that yielded a non-linear formula of Rs. Later, Brent’s algorithm was used to precisely estimate Rs at every fine-tuned point of n, thereby all other parameters were determined. The set of parameters that provided the lowest root mean square error (RMSE) between the experimental and simulated I-V data were chosen to be optimum. The proposed Brent’s algorithm (BA) was shown outperform several recently reported computational and heuristic algorithms that were exploited to mine the single-diode model parameters for solar cells and modules with varied device temperatures and solar irradiation conditions.
关键词： Parameters extraction,Brent’s algorithm,Solar cells and modules,Sensitivity analysis,I-V simulation
更新于2025-09-19 17:13:59
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Deep-Space Optical Communication Link Engineering: Sensitivity Analysis
摘要： Science and exploration missions are continuously enlarging the science volume generated onboard the spacecraft, limited typically by the capabilities of the communication link. Although the rather unexploited Ka-band allocation around 32 GHz provides some relief in this respect [1], particularly if used with large size high gain antennas, optical communications bear the promise of delivering higher data rates in the mid-term [2]. For setting the scene for the optical communications technology, it is always interesting to understand where the limits are of current RF-based deep-space systems. Toward this, [3] is extrapolating the performance of Payload Data Transmitters from the current state-of-the-art to the 2023 technology time frame (see Table 1). Coming now to the technology which is the scope of this paper, for deep-space optical communications, the space agencies in Consultative Committee for Space Data Systems (CCSDS) recently concluded on a standard for high photon efficiency (HPE). The standard comprises a specification on the coding and synchronization layer [4] and one on the physical layer [5]. After specifying the standard, space agencies are now focused on planning in orbit demonstrations (IOD), although the waveform of [4] was already demonstrated to laser a frame of in the extent lunar large the Authors’ current addresses: N. K. Lyras, School of Electrical and Computer Engineering, National Technical University of Athens, Athens 15780, Greece. A. D. Panagopoulos, School of Electrical and Computer Engineering, National Technical University of Athens, Athens 15780, Greece, E-mail: (thpanag@ece.ntua.gr). P.-D. Arapoglou, European Space Agency/ESTEC, Noordwijk 2200, The Netherlands. Manuscript received January 15, 2019, revised July 5, 2019, and ready for publication September 24, 2019. Review handled by Prof. Mauro De Sanctis. 0885-8985/19/$26.00 (cid:1) 2019 IEEE communication demonstration [6]. From the European Space Agency point of view, a deep-space optical communication system IOD opportunity could be the space safety program, space weather mission to the Sun–Earth Lagrange point L5 [7]. In this paper, a tool is presented for aiding such IOD missions fully relying on the CCSDS HPE. The main elements that must be taken into account in a deep-space link budget analysis are summarized in Figure 1. The main assumptions of the work involve an optical downlink operating under cloud-free line of sight (CFLOS) conditions [8], [9] between an optical terminal onboard a deep-space spacecraft and an optical ground station. A Poisson is representative of deep-space optical channel model links. Due to the power limited nature of these links intensity modulation (IM) and direct detection (DD) with photon-counting detectors the transmitter and receiver architecture, respectively. Under these conditions, the pulse position modulation (PPM) signaling [11] and a serially concatenated pulse position modulation (SCPPM) [12] are capacity achieving. [10] are considered for Apart from performing a sensitivity analysis of various hypothetical deep-space missions, the paper presents a practical methodology that allows the link designer to select the main signaling parameters (modulation order, code rate, slot width), without resorting to lengthy coded bit error rate (BER) evaluations that otherwise need to be run for a large parameter set. This allows faster link budget calculations, e.g., for performing trade-off studies.
关键词： sensitivity analysis,deep-space optical communication,CCSDS HPE,link budget,photon-counting detectors
更新于2025-09-16 10:30:52
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Energy assessment and economic sensitivity analysis of a grid-connected photovoltaic system
摘要： This paper presents techno-economic assessment results of a grid-connected photovoltaic (PV) system for domestic building application. The PV system electricity output, energy conversion ef?ciency and cell temperature are explored based on the local weather condition, the system life cycle cost is evaluated with full account of the life of assets, volatile economic ?uctuations, uncertainty in?uence factors, net present value (NPV) and discounted payback period (DPP) under Feed-in Tariff (FiT) scheme, the annual savings and payback time are compared for the FiT and new Smart Export Guarantee (SEG) schemes. Technical analysis results indicate that the system is capable of ful?lling the building electrical energy demand from April to October, and the extra electricity of 1530.23 kWh is exported to the grid in this period. The life cycle cost assessment results illustrate that the system achieves a NPV of ￡1335.32 and has a DPP of 9.34 years under the FiT scheme. Moreover, the sensitive analyses reveal that the high discount rate decreases the system NPV whereas the high initial cost leads to long payback period to realize the positive NPV. Furthermore, the FiT is the most cost-effective solution for PV system and has the shortest DPP compared with the SEG.
关键词： Techno-economic assessment,Photovoltaic system,Feed-in tariff,Smart export guarantee,Economic sensitivity analysis
更新于2025-09-16 10:30:52
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Neural networks based prediction modelling of hybrid laser beam welding process parameters with sensitivity analysis
摘要： Present paper attempted to model complex relationship between CO2 laser–MIG hybrid welding parameters and it has been completed using different algorithms of artificial neural networks (ANN). Input parameters for the study include laser power, welding speeds and wires feed rate and tensile strength of the joint is considered as output. A full factorial experimental dataset is used for the purpose. Variants of back propagation neural networks (BPNN) and Radial Basis Function Networks have been used as training algorithm. Altogether 65 different ANN architecture have been trained and tested using 6 different training algorithms to find out ANN with best prediction capability. 3-11-1 ANN architecture trained using BPNN with Bayesian regularization shows best prediction capability (mean square error 3.24E ? 04) and considered as Best ANN. That ANN will be useful for determining required value of welding process parameters to yield a specific welding strength and suitable for online process monitoring and control. Finally, a sensitivity analysis has been conducted and it is found that, maximum welding strength can be obtained with low wire feed rate (4 m/min), low welding speed (2 m/min) and high laser power (3 kW).
关键词： Sensitivity analysis,Hybrid CO2 laser-MIG welding,Artificial neural networks
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Xi'an, China (2019.6.3-2019.6.6)] 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Reliability Evaluation of Photovoltaic Power Generation System Based on Fuzzy Layering Method
摘要： The analysis process of the overall reliability evaluation model of the traditional photovoltaic power generation system is complicated, and the shortcomings of the system weak link cannot be analyzed. This paper proposes a fuzzy hierarchical evaluation method based on sensitivity analysis to evaluate the reliability of photovoltaic power generation systems. The method judges the whole system failure factor by introducing the fault frequency, the degree of fault impact, and the second evaluation criterion of the fault detection difficulty. In particular, the Monte Carlo-based component sensitivity analysis method is used to calculate the degree of fault impact. Finally, the method of this paper is used to analyze a photovoltaic power generation system. The effectiveness of the proposed method is verified by the overall reliability analysis and the evaluation of fault factors. It is proved that the method is of great significance for analyzing the reliability of the photovoltaic system and the weak link of the system.
关键词： photovoltaic power generation system,sensitivity analysis,Monte Carlo,fuzzy layering evaluation method
更新于2025-09-16 10:30:52