221 research outputs found
Forecast with Forecasts: Diversity Matters
Forecast combination has been widely applied in the last few decades to
improve forecast accuracy. In recent years, the idea of using time series
features to construct forecast combination model has flourished in the
forecasting area. Although this idea has been proved to be beneficial in
several forecast competitions such as the M3 and M4 competitions, it may not be
practical in many situations. For example, the task of selecting appropriate
features to build forecasting models can be a big challenge for many
researchers. Even if there is one acceptable way to define the features,
existing features are estimated based on the historical patterns, which are
doomed to change in the future, or infeasible in the case of limited historical
data. In this work, we suggest a change of focus from the historical data to
the produced forecasts to extract features. We calculate the diversity of a
pool of models based on the corresponding forecasts as a decisive feature and
use meta-learning to construct diversity-based forecast combination models. A
rich set of time series are used to evaluate the performance of the proposed
method. Experimental results show that our diversity-based forecast combination
framework not only simplifies the modelling process but also achieves superior
forecasting performance.Comment: 23 pages, 4 figures, 4 table
A method for the suppression of fluctuations in the neutral-point potential of a three-level NPC inverter with a capacitor-voltage loop
This paper investigates the problem of fluctuation of the neutral-point potential (NPP) in a three-level NPC inverter with a capacitor-voltage loop. The phase pulse width duty cycle disturbance PWM method is proposed to suppress the NPP fluctuation efficiently. Based on the basic carrier-based Phase Disposition (PD) PWM method, the average pulse neutral-point current model is established. Then the frequency, amplitude and equivalent initial phase of the NPP fluctuation are analyzed based on the current model. According to the alternating error of the DC-link capacitor voltages, a capacitor-voltage loop with a quasi PR (proportional resonant) controller is presented. The control variable, which varies with the modulation index, phase current, load power factor, etc, can be obtained from the quasi PR controller. Finally, an experimental three-level NPC inverter is described and the validity and feasibility of the proposed method are verified by experimental results
Directive local color transfer based on dynamic look-up table
publishedVersionUnit-agreemen
Effect of Soy Lecithin, Glucose Oxidase, and Transglutaminase on Dough Rheology and Quality Properties of Steamed Bread Enriched with Potato Pulp
This study aimed to assess the effect of soy lecithin (Soy L, 0.2%–1.0%), glucose oxidase (GOX, 0.3–1.5 U/g), and transglutaminase (TG, 0.3–1.5 U/g) on dough elongation properties and texture qualities of steamed bread. The optimum formulation of steamed bread prepared from wheat flour (50%) and potato pulp (50%) was investigated. Results showed that Soy L and GOX significantly (P < 0.05) affected the specific volume and hardness of steamed bread, whereas TG significantly (P < 0.05) affected the resistance to extension and extensibility of dough, as well as the springiness and cohesiveness of steamed bread. The optimum formulation consisting of 0.65% Soy L, 0.92 U/g GOX, and 0.96 U/g TG increased the viscoelasticity and fermentation characteristics of dough and improved the specific volume, texture, and porosity of steamed bread enriched with potato pulp
Integration of scRNA-Seq and bulk RNA-Seq uncover perturbed immune cell types and pathways of Kawasaki disease
IntroductionKawasaki disease (KD) is an acute febrile illness primarily affecting children and characterized by systemic inflammation and vasculitis that can lead to coronary artery complications. The aim of this study was to gain a comprehensive understanding of immune dysregulation in KD.MethodsTo this end, we employed integration of single-cell RNA sequencing (scRNA-Seq) and bulk RNA sequencing (bulk RNA-Seq) data. Furthermore, we conducted flow cytometry analysis for a cohort of 82 KD patients.ResultsOur analysis revealed significant heterogeneity within immune cell populations in KD patients, with distinct clusters of T cells, B cells, and natural killer (NK) cells. Importantly, CD4+ naïve T cells in KD patients were found to predominantly differentiate into Treg cells and Th2 cells, potentially playing a role in the excessive inflammation and vascular damage characteristic of the disease. Dysregulated signaling pathways were also identified, including the mTOR signaling pathway, cardiomyopathy pathway, COVID-19 signaling pathway, and pathways involved in bacterial or viral infection.DiscussionThese findings provide insights into the immunopathogenesis of KD, emphasizing the importance of immune cell dysregulation and dysregulated signaling pathways. Integration of scRNA-Seq and bulk RNA-Seq data offers a comprehensive view of the molecular and cellular alterations in KD and highlights potential therapeutic targets for further investigation. Validation and functional studies are warranted to elucidate the roles of the identified immune cell types and pathways in KD pathogenesis and to develop targeted interventions to improve patient outcomes
Determination of key enzymes for threonine synthesis through in vitro metabolic pathway analysis
Figure S1. The pathway flux (J) in the in vitro system when one enzyme concentration was increased. (A) The pathway flux when purified ThrA was added to the crude enzyme extract. (B) The pathway flux when purified Asd was added to the crude enzyme extract. (C) The pathway flux when purified ThrB was added to the crude enzyme extract. (D) The pathway flux when purified ThrC was added to the crude enzyme extract
Wideband Power Spectrum Sensing: a Fast Practical Solution for Nyquist Folding Receiver
The limited availability of spectrum resources has been growing into a
critical problem in wireless communications, remote sensing, and electronic
surveillance, etc. To address the high-speed sampling bottleneck of wideband
spectrum sensing, a fast and practical solution of power spectrum estimation
for Nyquist folding receiver (NYFR) is proposed in this paper. The NYFR
architectures is can theoretically achieve the full-band signal sensing with a
hundred percent of probability of intercept. But the existing algorithm is
difficult to realize in real-time due to its high complexity and complicated
calculations. By exploring the sub-sampling principle inherent in NYFR, a
computationally efficient method is introduced with compressive covariance
sensing. That can be efficient implemented via only the non-uniform fast
Fourier transform, fast Fourier transform, and some simple multiplication
operations. Meanwhile, the state-of-the-art power spectrum reconstruction model
for NYFR of time-domain and frequency-domain is constructed in this paper as a
comparison. Furthermore, the computational complexity of the proposed method
scales linearly with the Nyquist-rate sampled number of samples and the
sparsity of spectrum occupancy. Simulation results and discussion demonstrate
that the low complexity in sampling and computation is a more practical
solution to meet the real-time wideband spectrum sensing applications
Distributed UAV Swarm Augmented Wideband Spectrum Sensing Using Nyquist Folding Receiver
Distributed unmanned aerial vehicle (UAV) swarms are formed by multiple UAVs
with increased portability, higher levels of sensing capabilities, and more
powerful autonomy. These features make them attractive for many recent
applica-tions, potentially increasing the shortage of spectrum resources. In
this paper, wideband spectrum sensing augmented technology is discussed for
distributed UAV swarms to improve the utilization of spectrum. However, the
sub-Nyquist sampling applied in existing schemes has high hardware complexity,
power consumption, and low recovery efficiency for non-strictly sparse
conditions. Thus, the Nyquist folding receiver (NYFR) is considered for the
distributed UAV swarms, which can theoretically achieve full-band spectrum
detection and reception using a single analog-to-digital converter (ADC) at low
speed for all circuit components. There is a focus on the sensing model of two
multichannel scenarios for the distributed UAV swarms, one with a complete
functional receiver for the UAV swarm with RIS, and another with a
decentralized UAV swarm equipped with a complete functional receiver for each
UAV element. The key issue is to consider whether the application of RIS
technology will bring advantages to spectrum sensing and the data fusion
problem of decentralized UAV swarms based on the NYFR architecture. Therefore,
the property for multiple pulse reconstruction is analyzed through the
Gershgorin circle theorem, especially for very short pulses. Further, the block
sparse recovery property is analyzed for wide bandwidth signals. The proposed
technology can improve the processing capability for multiple signals and wide
bandwidth signals while reducing interference from folded noise and subsampled
harmonics. Experiment results show augmented spectrum sensing efficiency under
non-strictly sparse conditions
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