1,721,040 research outputs found
Translocation of polymerase-associated factor 1 complex(Paf1C) components cytosolic stress granule
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Microgrid Optimal Scheduling Incorporating Remaining Useful Life and Performance Degradation of Distributed Generators
No full textAuthorThis study presents a novel microgrid optimal scheduling strategy, which considers the degradation of distributed generators (DGs). DGs affected by degradation exhibit reduced generation efficiency and capacity. Operating the microgrid without consideration of these impacts increases operating and management costs and reduces reliability and stability. To overcome this problem, we developed a new optimal scheduling strategy that considers the degradation of DGs. This study focuses on a permanent magnet synchronous generator, which is widely used as DGs recently, and on the degradation of stator insulation, which is one of the most frequently occurring forms of degradation. The reduction in performance caused by insulation degradation is analyzed using finite element analysis and is integrated into the optimal scheduling strategy. We demonstrate that the proposed strategy operates a microgrid more economically through a reduction of total operating costs, achieved by adaptively accounting for the increase in operating costs and the reduction of capacity arising from degradation. In addition, the sudden shutdown of a DG can be prevented by predicting its remaining useful life and incorporating it into the optimal scheduling strategy. The effectiveness and feasibility of the proposed strategy are confirmed using various case studies.11Nsciescopu
Detection and Classification of Demagnetization and Interturn Short Faults of IPMSMs
No full textWe present a method that detects and classifies demagnetization and interturn short faults (ISFs), which degrade the performance of permanent-magnet synchronous machines (PMSMs). Demagnetization and ISF are analyzed using models; we focused on changes of magnitude and angle of currents in the synchronous frame. Those two faults increase the magnitude of the input current compared with normal machines at the same load torque. However, our analysis suggests that demagnetization causes increase in the current angle beta, whereas ISF causes decrease in beta. We exploit this difference in response to classify the fault if one is detected in the PMSM. Experimental studies on interior-type PMSMs verify that demagnetization and ISF can be detected and classified in various operation conditions.113sciescopu
Wavelet-like convolutional neural network structure for time-series data classification
No full textTime-series data often contain one of the most valuable pieces of information in many fields including manufacturing. Because time-series data are relatively cheap to acquire, they (e.g., vibration signals) have become a crucial part of big data even in manufacturing shop floors. Recently, deep-learning models have shown state-of-art performance for analyzing big data because of their sophisticated structures and considerable computational power. Traditional models for a machinery-monitoring system have highly relied on features selected by human experts. In addition, the representational power of such models fails as the data distribution becomes complicated. On the other hand, deep-learning models automatically select highly abstracted features during the optimization process, and their representational power is better than that of traditional neural network models. However, the applicability of deep-learning models to the field of prognostics and health management (PHM) has not been well investigated yet. This study integrates the "residual fitting" mechanism inherently embedded in the wavelet transform into the convolutional neural network deep-learning structure. As a result, the architecture combines a signal smoother and classification procedures into a single model. Validation results from rotor vibration data demonstrate that our model outperforms all other off-the-shelf feature-based models
Detection of Inter-turn Short Circuit Faults in Permanent Magnet Synchronous Motors with Multistrands Windings
No full textIn Permanent Magnet Synchronous Motors (PMSMs) with multistrands windings, inter-turn short circuit (ITSC) faults occur in two types. One is that the ITSC fault occurs between two spots of a single strand and the other is that the ITSC fault occurs between two different strands. We proposed a fault indicator to detect two types of inter-turn short circuit faults in PMSMs that have multistrands windings. The fault indicator is calculated from stationary dq currents and their Hilbert transforms. The fault indicator converges to zero in healthy state but increases proportionally to the severity of the fault in faulty state. We validated the fault indicator with finite element method (FEM) simulation data. The proposed fault indicator only uses current data, so the indicator is simple and efficient tool to detect ITSC faults in PMSMs with multistrands windings.1
Detection of Interturn Short-Circuit Fault and Demagnetization Fault in IPMSM by 1-D Convolutional Neural Network
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Perceptual Space of Regular Homogeneous Haptic Textures Rendered Using Electrovibration
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Solar-induced chlorophyll fluorescence is non-linearly related to canopy photosynthesis in a temperate evergreen needleleaf forest during the fall transition
No full textSolar-induced chlorophyll fluorescence (SIF) provides us with new opportunities to understand the physiological and structural dynamics of vegetation from leaf to global scales. However, the relationships between SIF and gross primary productivity (GPP) are not fully understood, which is mainly due to the challenges of decoupling structural and physiological factors that control the relationships. Here, we report the results of continuous observations of canopy-level SIF, GPP, absorbed photosynthetically active radiation (APAR), and chlorophyll: carotenoid index (CCI) in a temperate evergreen needleleaf forest. To understand the mechanisms underlying the relationship between GPP and SIF, we investigated the relationships of light use efficiency (LUEp), chlorophyll fluorescence yield (?F), and the fraction of emitted SIF photons escaping from the canopy (fesc) separately. We found a strongly non-linear relationship between GPP and SIF at diurnal and seasonal time scales (R2 = 0.91 with a hyperbolic regression function, daily). GPP saturated with APAR, while SIF did not. Also, there were differential responses of LUEp and ?F to air temperature. While LUEp reached saturation at high air temperatures, ?F did not saturate. We found that the canopy-level chlorophyll: carotenoid index was strongly correlated to canopy-level ?F (R2 = 0.84) implying that ?F could be more closely related to pigment pool changes rather than LUEp. In addition, we found that the fesc contributed to a stronger SIF-GPP relationship by partially capturing the response of LUEp to diffuse light. These findings can help refine physiological and structural links between canopy-level SIF and GPP in evergreen needleleaf forest.N
On the interface electron transport problem of highly active IrOx catalysts
No full textElectron transport resistance at the interface between the catalyst layer (CL) and the porous transport layer (PTL) in the PEMWE anode has long been poorly understood despite its significant impact on performance. In this study, we demonstrate that highly active IrOx nanocatalysts encounter electron transport problems at the interface with the native oxide (TiOx) on the Ti PTL, leading to poor single-cell performance. This issue is attributed to the pinch-off effect caused by the ionomer, which withdraws electrons from TiOx at the interface, creating a severe electron depletion layer. The problem is further exacerbated at the TiOx interface of ultrafine IrOx nanocatalysts, as small-sized catalyst particles form dense CL structures, amplifying the influence of the expanded ionomer/TiOx interface on the entire region. By manipulating the particle size of the IrOx catalyst, we demonstrate this effect at the single-cell level and further validate it through COMSOL Multiphysics simulations. Our findings reveal that IrOx catalysts larger than 20 nm are necessary to mitigate the significant interference caused by the ionomer at the TiOx interface. This work provides critical insights into optimizing catalyst particle dimensions to overcome the pinch-off effect and enhance performance.
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