427 research outputs found
Fault feature extraction method based on EWT-SMF and MF-DFA for valve fault of reciprocating compressor
According to the nonlinearity and nonstationarity characteristics of reciprocating compressor vibration signal, a fault feature extraction method of reciprocating compressor based on the empirical wavelet transform (EWT) and state-adaptive morphological filtering (SMF) is proposed. Firstly, an adaptive empirical wavelet transform was used to divide the Fourier spectrum by constructing a scale-space curve, and an appropriate orthogonal wavelet filter bank was constructed to extract the AM-FM component with a tightly-supported Fourier spectrum. Then according to the impact characteristic of the reciprocating compressor vibration signal, the morphological structural elements were constructed with the characteristics of the signal to perform state-adaptive morphological filtering on the partitioned modal functions. Finally, the MF-DFA method of the modal function was quantitatively analyzed and the fault identification was performed. By analyzing the experimental data, it can be shown that the method can effectively identify the fault type of reciprocating compressor valve
Docking system design and self-assembly control of distributed swarm flying robots
This paper presents a novel docking system design and the distributed self-assembly control strategy for a Distributed Swarm Flying Robot (DSFR). The DSFR is a swarm robot comprising many identical robot modules that are able to move on the ground, dock with each other and fly coordinately once self-assembled into a robotic structure. A generalized adjacency matrix method is proposed to describe the configurations of robotic structures. Based on the docking system and the adjacency matrix, experiments are performed to demonstrate and verify the self-assembly control strategy
Fast Propagation is Better: Accelerating Single-Step Adversarial Training via Sampling Subnetworks
Adversarial training has shown promise in building robust models against
adversarial examples. A major drawback of adversarial training is the
computational overhead introduced by the generation of adversarial examples. To
overcome this limitation, adversarial training based on single-step attacks has
been explored. Previous work improves the single-step adversarial training from
different perspectives, e.g., sample initialization, loss regularization, and
training strategy. Almost all of them treat the underlying model as a black
box. In this work, we propose to exploit the interior building blocks of the
model to improve efficiency. Specifically, we propose to dynamically sample
lightweight subnetworks as a surrogate model during training. By doing this,
both the forward and backward passes can be accelerated for efficient
adversarial training. Besides, we provide theoretical analysis to show the
model robustness can be improved by the single-step adversarial training with
sampled subnetworks. Furthermore, we propose a novel sampling strategy where
the sampling varies from layer to layer and from iteration to iteration.
Compared with previous methods, our method not only reduces the training cost
but also achieves better model robustness. Evaluations on a series of popular
datasets demonstrate the effectiveness of the proposed FB-Better. Our code has
been released at https://github.com/jiaxiaojunQAQ/FP-Better
FireFly v2: Advancing Hardware Support for High-Performance Spiking Neural Network with a Spatiotemporal FPGA Accelerator
Spiking Neural Networks (SNNs) are expected to be a promising alternative to
Artificial Neural Networks (ANNs) due to their strong biological
interpretability and high energy efficiency. Specialized SNN hardware offers
clear advantages over general-purpose devices in terms of power and
performance. However, there's still room to advance hardware support for
state-of-the-art (SOTA) SNN algorithms and improve computation and memory
efficiency. As a further step in supporting high-performance SNNs on
specialized hardware, we introduce FireFly v2, an FPGA SNN accelerator that can
address the issue of non-spike operation in current SOTA SNN algorithms, which
presents an obstacle in the end-to-end deployment onto existing SNN hardware.
To more effectively align with the SNN characteristics, we design a
spatiotemporal dataflow that allows four dimensions of parallelism and
eliminates the need for membrane potential storage, enabling on-the-fly spike
processing and spike generation. To further improve hardware acceleration
performance, we develop a high-performance spike computing engine as a backend
based on a systolic array operating at 500-600MHz. To the best of our
knowledge, FireFly v2 achieves the highest clock frequency among all FPGA-based
implementations. Furthermore, it stands as the first SNN accelerator capable of
supporting non-spike operations, which are commonly used in advanced SNN
algorithms. FireFly v2 has doubled the throughput and DSP efficiency when
compared to our previous version of FireFly and it exhibits 1.33 times the DSP
efficiency and 1.42 times the power efficiency compared to the current most
advanced FPGA accelerators
FireFly: A High-Throughput and Reconfigurable Hardware Accelerator for Spiking Neural Networks
Spiking neural networks (SNNs) have been widely used due to their strong
biological interpretability and high energy efficiency. With the introduction
of the backpropagation algorithm and surrogate gradient, the structure of
spiking neural networks has become more complex, and the performance gap with
artificial neural networks has gradually decreased. However, most SNN hardware
implementations for field-programmable gate arrays (FPGAs) cannot meet
arithmetic or memory efficiency requirements, which significantly restricts the
development of SNNs. They do not delve into the arithmetic operations between
the binary spikes and synaptic weights or assume unlimited on-chip RAM
resources by using overly expensive devices on small tasks. To improve
arithmetic efficiency, we analyze the neural dynamics of spiking neurons,
generalize the SNN arithmetic operation to the multiplex-accumulate operation,
and propose a high-performance implementation of such operation by utilizing
the DSP48E2 hard block in Xilinx Ultrascale FPGAs. To improve memory
efficiency, we design a memory system to enable efficient synaptic weights and
membrane voltage memory access with reasonable on-chip RAM consumption.
Combining the above two improvements, we propose an FPGA accelerator that can
process spikes generated by the firing neuron on-the-fly (FireFly). FireFly is
implemented on several FPGA edge devices with limited resources but still
guarantees a peak performance of 5.53TSOP/s at 300MHz. As a lightweight
accelerator, FireFly achieves the highest computational density efficiency
compared with existing research using large FPGA devices
Do DALL-E and Flamingo Understand Each Other?
The field of multimodal research focusing on the comprehension and creation
of both images and text has witnessed significant strides. This progress is
exemplified by the emergence of sophisticated models dedicated to image
captioning at scale, such as the notable Flamingo model and text-to-image
generative models, with DALL-E serving as a prominent example. An interesting
question worth exploring in this domain is whether Flamingo and DALL-E
understand each other. To study this question, we propose a reconstruction task
where Flamingo generates a description for a given image and DALL-E uses this
description as input to synthesize a new image. We argue that these models
understand each other if the generated image is similar to the given image.
Specifically, we study the relationship between the quality of the image
reconstruction and that of the text generation. We find that an optimal
description of an image is one that gives rise to a generated image similar to
the original one. The finding motivates us to propose a unified framework to
finetune the text-to-image and image-to-text models. Concretely, the
reconstruction part forms a regularization loss to guide the tuning of the
models. Extensive experiments on multiple datasets with different image
captioning and image generation models validate our findings and demonstrate
the effectiveness of our proposed unified framework. As DALL-E and Flamingo are
not publicly available, we use Stable Diffusion and BLIP in the remaining work.
Project website: https://dalleflamingo.github.io.Comment: Accepted to ICCV 202
Domain-invariant Feature Exploration for Domain Generalization
Deep learning has achieved great success in the past few years. However, the
performance of deep learning is likely to impede in face of non-IID situations.
Domain generalization (DG) enables a model to generalize to an unseen test
distribution, i.e., to learn domain-invariant representations. In this paper,
we argue that domain-invariant features should be originating from both
internal and mutual sides. Internal invariance means that the features can be
learned with a single domain and the features capture intrinsic semantics of
data, i.e., the property within a domain, which is agnostic to other domains.
Mutual invariance means that the features can be learned with multiple domains
(cross-domain) and the features contain common information, i.e., the
transferable features w.r.t. other domains. We then propose DIFEX for
Domain-Invariant Feature EXploration. DIFEX employs a knowledge distillation
framework to capture the high-level Fourier phase as the internally-invariant
features and learn cross-domain correlation alignment as the mutually-invariant
features. We further design an exploration loss to increase the feature
diversity for better generalization. Extensive experiments on both time-series
and visual benchmarks demonstrate that the proposed DIFEX achieves
state-of-the-art performance.Comment: Accepted by Transactions on Machine Learning Research (TMLR) 2022; 20
pages; code:
https://github.com/jindongwang/transferlearning/tree/master/code/DeepD
iTRAQ-Based Comparative Proteomic Analysis Reveals Molecular Mechanisms Underlying Wing Dimorphism of the Pea Aphid, Acyrthosiphon pisum
Wing dimorphism is a widespread phenomenon in insects with an associated trade-off between flight capability and fecundity. Despite the molecular underpinnings of phenotypic plasticity that has already been elucidated, it is still not fully understood. In this study, we focused on the differential proteomics profiles between alate and apterous morphs of the pea aphid, Acyrthosiphon pisum at the fourth instar nymph and adult stages, using isobaric tags for relative and absolute quantitation (iTRAQ) in a proteomic-based approach. A total of 5,116 protein groups were identified and quantified in the three biological replicates, of which 836 were differentially expressed between alate and apterous morphs. A bioinformatics analysis of differentially expressed protein groups (DEPGs) was performed based on gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). KEGG enrichment analysis showed that DEPGs mainly participated in energy metabolism, amino acid biosynthesis and metabolism, and signal sensing and transduction. To verify the reliability of proteomics data, the transcriptional expression of 29 candidates of differentially expressed proteins were analyzed by quantitative real-time PCR (qRT-PCR), showing that 26 genes were consistent with those at proteomic levels. In addition, differentially expressed proteins between winged and wingless morphs that were linked to olfactory sense were investigated. Quantitative real-time PCR revealed the tissue- and morph-biased expression profiles. These results suggested that olfactory sense plays a key role in wing dimorphism of aphids. The comparative proteomic analysis between alate and apterous morphs of the pea aphid provides a novel insight into wing development and dimorphism in aphids and will help facilitate our understanding of these concepts at molecular levels
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A photo-responsive F-box protein FOF2 regulates floral initiation by promoting FLC expression in Arabidopsis.
Floral initiation is regulated by various genetic pathways in response to light, temperature, hormones and developmental status; however, the molecular mechanisms underlying the interactions between different genetic pathways are not fully understood. Here, we show that the photoresponsive gene FOF2 (F-box of flowering 2) negatively regulates flowering. FOF2 encodes a putative F-box protein that interacts specifically with ASK14, and its overexpression results in later flowering under both long-day and short-day photoperiods. Conversely, transgenic plants expressing the F-box domain deletion mutant of FOF2 (FOF2ΔF), or double loss of function mutant of FOF2 and FOL1 (FOF2-LIKE 1) present early flowering phenotypes. The late flowering phenotype of the FOF2 overexpression lines is suppressed by the flc-3 loss-of-function mutation. Furthermore, FOF2 mRNA expression is regulated by autonomous pathway gene FCA, and the repressive effect of FOF2 in flowering can be overcome by vernalization. Interestingly, FOF2 expression is regulated by light. The protein level of FOF2 accumulates in response to light, whereas it is degraded under dark conditions via the 26S proteasome pathway. Our findings suggest a possible mechanistic link between light conditions and the autonomous floral promotion pathway in Arabidopsis
Wav2vec-S: Semi-Supervised Pre-Training for Low-Resource ASR
Self-supervised pre-training could effectively improve the performance of
low-resource automatic speech recognition (ASR). However, existing
self-supervised pre-training are task-agnostic, i.e., could be applied to
various downstream tasks. Although it enlarges the scope of its application,
the capacity of the pre-trained model is not fully utilized for the ASR task,
and the learned representations may not be optimal for ASR. In this work, in
order to build a better pre-trained model for low-resource ASR, we propose a
pre-training approach called wav2vec-S, where we use task-specific
semi-supervised pre-training to refine the self-supervised pre-trained model
for the ASR task thus more effectively utilize the capacity of the pre-trained
model to generate task-specific representations for ASR. Experiments show that
compared to wav2vec 2.0, wav2vec-S only requires a marginal increment of
pre-training time but could significantly improve ASR performance on in-domain,
cross-domain and cross-lingual datasets. Average relative WER reductions are
24.5% and 6.6% for 1h and 10h fine-tuning, respectively. Furthermore, we show
that semi-supervised pre-training could close the representation gap between
the self-supervised pre-trained model and the corresponding fine-tuned model
through canonical correlation analysis.Comment: Accepted by Interspeech 202
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