84 research outputs found
Fiber-optic refractometer based on a phase-shifted fiber Bragg grating on a side-hole fiber
A fiber-optic refractive index (RI) sensor based on a π-phaseshifted fiber-Bragg-grating (πFBG) inscribed on a side-hole fiber is presented. The reflection spectrum of the πFBG features two narrow notches associated with the two polarization modes and the spectral spacing of the notches is used for high-sensitivity RI sensing with little temperature cross-sensitivity. The side-hole fiber maintains its outer diameter and mechanical strength. The side-hole fiber is also naturally integrated into a microfluidic system for convenient sample delivery and reduced sample amount. A novel demodulation method based on laser frequency modulation to enhance the sensor dynamic range is proposed and demonstrated
Initial value generation for matchmaking in middle agents
One of the major challenges that agents used in open environments must face is that they must be able to find each other. This is because in an open environment, agents might appear and disappear unpredictably. To address this issue, middle agents have been proposed. The performance of middle agents relies heavily on the matchmaking algorithms used. Matchmaking is the process of finding an appropriate provider for a requester through a middle agent. The practical performance of service provider agents has a significant impact on the matchmaking outcomes of middle agents. Thus the track records of agents in accomplishing similar tasks in the past should be taken into account in matchmaking process. Considering that there are no track records available at the launching of an agent system, this paper discusses some ways to provide reasonable initial values for the track records. With the agents\u27 history and the initial vallies ofthe track records, the performance of matchmaking algorithms can be improved significantly.<br /
Model Inversion Attack via Dynamic Memory Learning
Model Inversion (MI) attacks aim to recover the private training data from
the target model, which has raised security concerns about the deployment of
DNNs in practice. Recent advances in generative adversarial models have
rendered them particularly effective in MI attacks, primarily due to their
ability to generate high-fidelity and perceptually realistic images that
closely resemble the target data. In this work, we propose a novel Dynamic
Memory Model Inversion Attack (DMMIA) to leverage historically learned
knowledge, which interacts with samples (during the training) to induce diverse
generations. DMMIA constructs two types of prototypes to inject the information
about historically learned knowledge: Intra-class Multicentric Representation
(IMR) representing target-related concepts by multiple learnable prototypes,
and Inter-class Discriminative Representation (IDR) characterizing the
memorized samples as learned prototypes to capture more privacy-related
information. As a result, our DMMIA has a more informative representation,
which brings more diverse and discriminative generated results. Experiments on
multiple benchmarks show that DMMIA performs better than state-of-the-art MI
attack methods
Robust Automatic Speech Recognition via WavAugment Guided Phoneme Adversarial Training
Developing a practically-robust automatic speech recognition (ASR) is
challenging since the model should not only maintain the original performance
on clean samples, but also achieve consistent efficacy under small volume
perturbations and large domain shifts. To address this problem, we propose a
novel WavAugment Guided Phoneme Adversarial Training (wapat). wapat use
adversarial examples in phoneme space as augmentation to make the model
invariant to minor fluctuations in phoneme representation and preserve the
performance on clean samples. In addition, wapat utilizes the phoneme
representation of augmented samples to guide the generation of adversaries,
which helps to find more stable and diverse gradient-directions, resulting in
improved generalization. Extensive experiments demonstrate the effectiveness of
wapat on End-to-end Speech Challenge Benchmark (ESB). Notably, SpeechLM-wapat
outperforms the original model by 6.28% WER reduction on ESB, achieving the new
state-of-the-art
TransAudio: Towards the Transferable Adversarial Audio Attack via Learning Contextualized Perturbations
In a transfer-based attack against Automatic Speech Recognition (ASR)
systems, attacks are unable to access the architecture and parameters of the
target model. Existing attack methods are mostly investigated in voice
assistant scenarios with restricted voice commands, prohibiting their
applicability to more general ASR related applications. To tackle this
challenge, we propose a novel contextualized attack with deletion, insertion,
and substitution adversarial behaviors, namely TransAudio, which achieves
arbitrary word-level attacks based on the proposed two-stage framework. To
strengthen the attack transferability, we further introduce an audio
score-matching optimization strategy to regularize the training process, which
mitigates adversarial example over-fitting to the surrogate model. Extensive
experiments and analysis demonstrate the effectiveness of TransAudio against
open-source ASR models and commercial APIs
Enhance the Visual Representation via Discrete Adversarial Training
Adversarial Training (AT), which is commonly accepted as one of the most
effective approaches defending against adversarial examples, can largely harm
the standard performance, thus has limited usefulness on industrial-scale
production and applications. Surprisingly, this phenomenon is totally opposite
in Natural Language Processing (NLP) task, where AT can even benefit for
generalization. We notice the merit of AT in NLP tasks could derive from the
discrete and symbolic input space. For borrowing the advantage from NLP-style
AT, we propose Discrete Adversarial Training (DAT). DAT leverages VQGAN to
reform the image data to discrete text-like inputs, i.e. visual words. Then it
minimizes the maximal risk on such discrete images with symbolic adversarial
perturbations. We further give an explanation from the perspective of
distribution to demonstrate the effectiveness of DAT. As a plug-and-play
technique for enhancing the visual representation, DAT achieves significant
improvement on multiple tasks including image classification, object detection
and self-supervised learning. Especially, the model pre-trained with Masked
Auto-Encoding (MAE) and fine-tuned by our DAT without extra data can get 31.40
mCE on ImageNet-C and 32.77% top-1 accuracy on Stylized-ImageNet, building the
new state-of-the-art. The code will be available at
https://github.com/alibaba/easyrobust.Comment: Accepted to NeurIPS 2022, https://github.com/alibaba/easyrobus
Preferential flow in the understory soil of Hippophae rhamnoides at different stump heights
This study aimed to clarify the effects of stumping on preferential flow in the understory soils of Hippophae rhamnoides and to assess appropriate stumping height for optimization of preferential flow. Root properties, soil properties, and preferential flow for different H. rhamnoides stump heights (0, 10, 15, 20Â cm, and no-stumping, labeled conditions S1, S2, S3, S4, and CK, respectively) were studied using in situ dye-tracing and laboratory analysis. The results showed that stumping significantly increased preferential flow development. This effect was maximized in condition S3, with dye-tracing coverage (DC) of 36.77%, maximum dye depth (MaxD) of 40.02 cm, uniform infiltration depth (Unifr) of 14.28 cm, preferential flow ratio (PFfr) of 23.85%, and length index (LI) of 96.72%. In terms of root length density (RLD), root mass density (RMD), root surface area density (RSAD), soil water content (SWC), soil total porosity (TP), mean weight diameter (MWD), and soil organic matter (SOM), the conditions were ranked S3>S2>S1>S3>CK; for root average diameter (RAD), they were ranked S3<S2<S1<S4<CK. Structural equation modeling showed that DC was affected directly by TP, MWD, and SWC and indirectly by RAD, RLD, RMD, RSAD, and SOM, explaining up to 89.1% of the variance. Thus, stumping of H. rhamnoides affected soil properties through the mechanism of root development, thereby improving preferential flow development in the soil and soil infiltration. The optimal stump height was 15Â cm. These findings are critical for vegetation recovery and for prevention and control of soil erosion in feldspathic sandstone areas
Model-enhanced Vector Index
Embedding-based retrieval methods construct vector indices to search for
document representations that are most similar to the query representations.
They are widely used in document retrieval due to low latency and decent recall
performance. Recent research indicates that deep retrieval solutions offer
better model quality, but are hindered by unacceptable serving latency and the
inability to support document updates. In this paper, we aim to enhance the
vector index with end-to-end deep generative models, leveraging the
differentiable advantages of deep retrieval models while maintaining desirable
serving efficiency. We propose Model-enhanced Vector Index (MEVI), a
differentiable model-enhanced index empowered by a twin-tower representation
model. MEVI leverages a Residual Quantization (RQ) codebook to bridge the
sequence-to-sequence deep retrieval and embedding-based models. To
substantially reduce the inference time, instead of decoding the unique
document ids in long sequential steps, we first generate some semantic virtual
cluster ids of candidate documents in a small number of steps, and then
leverage the well-adapted embedding vectors to further perform a fine-grained
search for the relevant documents in the candidate virtual clusters. We
empirically show that our model achieves better performance on the commonly
used academic benchmarks MSMARCO Passage and Natural Questions, with comparable
serving latency to dense retrieval solutions
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
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