489 research outputs found
Electrospun Polyvinyl Alcohol/Cellulose Nanocrystals Composite Nanofibrous Filter: Investigation of Fabrication and Application
Particulate matter (PM) pollution has become a global environmental issue because it poses threat to public health. To protect individuals from PM exposure, one common method is using air filters for indoor air purification. However, conventional air filters have various drawbacks, such as high air resistance, the filters are not fabricated with environmentally friendly technology, and they cannot be easily regenerated. In this dissertation, a new electrospun poly(vinyl alcohol) (PVA)/cellulose nanocrystals (CNCs) composite nanofibrous filter was successfully developed. This PVA/CNCs composite material was demonstrated as air filter for the first time. The CNCs improved the filtration performance by increasing the surface charge density of the electrospinning suspension and thereby reducing diameter of fibers. High PM2.5 removal efficiency was achieved (99.1%) with low pressure drop (91 Pa) at a relatively high airflow velocity (0.2 m s-1), under extremely polluted condition (PM2.5 mass concentration \u3e500 μg m-3). The integral effect of various electrospinning suspension properties on filtration performance was also investigated using response surface methodology. With a face-centered central composite design, the operating parameters for fabricating PVA/CNCs air filters were optimized, and the optimum conditions were a suspension concentration of 7.34% and a CNCs percentage of 20%. Additionally, the water-soluble PVA/CNCs composite was converted to be completely water-resistant when the electrospun material was heated at 140 oC for only 5 min. The mechanism of the change of water solubility of the fibers was investigated systematically. Our results revealed that increased crystallinity is the key factor for improving the aqueous stability, and CNCs provided additional nucleation sites for PVA crystallization during both electrospinning and heating process. The heated filters were effectively regenerated by water washing and the filtration performance was satisfactorily maintained. Because both PVA and CNCs are nontoxic and biodegradable, no organic solvents or crosslinking agents were used in the whole fabrication process, and the heating process is facile, the method proposed in this dissertation for fabricating electrospun PVA/CNCs nanofibrous filters is environmentally friendly and cost-effectively. This new cellulose-based air filter, which possesses high removal efficiency for PM, low pressure drop, and long lifetime, is very promising
Dynamic Patch-aware Enrichment Transformer for Occluded Person Re-Identification
Person re-identification (re-ID) continues to pose a significant challenge,
particularly in scenarios involving occlusions. Prior approaches aimed at
tackling occlusions have predominantly focused on aligning physical body
features through the utilization of external semantic cues. However, these
methods tend to be intricate and susceptible to noise. To address the
aforementioned challenges, we present an innovative end-to-end solution known
as the Dynamic Patch-aware Enrichment Transformer (DPEFormer). This model
effectively distinguishes human body information from occlusions automatically
and dynamically, eliminating the need for external detectors or precise image
alignment. Specifically, we introduce a dynamic patch token selection module
(DPSM). DPSM utilizes a label-guided proxy token as an intermediary to identify
informative occlusion-free tokens. These tokens are then selected for deriving
subsequent local part features. To facilitate the seamless integration of
global classification features with the finely detailed local features selected
by DPSM, we introduce a novel feature blending module (FBM). FBM enhances
feature representation through the complementary nature of information and the
exploitation of part diversity. Furthermore, to ensure that DPSM and the entire
DPEFormer can effectively learn with only identity labels, we also propose a
Realistic Occlusion Augmentation (ROA) strategy. This strategy leverages the
recent advances in the Segment Anything Model (SAM). As a result, it generates
occlusion images that closely resemble real-world occlusions, greatly enhancing
the subsequent contrastive learning process. Experiments on occluded and
holistic re-ID benchmarks signify a substantial advancement of DPEFormer over
existing state-of-the-art approaches. The code will be made publicly available.Comment: 12 pages, 6 figure
Di-μ-methanolato-κ4 O:O-bis[triÂchlorido(dimethylÂformamide-κO)tin(IV)]
The title compound, [Sn2(CH3O)2Cl6(C3H7NO)2], contains two hexaÂcoordinated SnIV atoms symmetrically bridged by two deprotonated methanol ligands, with an inversion center in the middle of the planar Sn2O2 ring. The other sites of the distorted octaÂhedral coordination geometry of the SnIV atom are occupied by three Cl atoms and one O atom from a dimethylÂformamide molÂecule. The complex molÂecules are connected by weak C—H⋯Cl hydrogen bonds into a two-dimensional supraÂmolecular network parallel to (10)
Optimal Distributed Controller Design for Nonlinear Coupled Dynamical Networks
This paper is concerned with the optimal distributed impulsive controller design for globally exponential synchronization of nonlinear dynamical networks with coupling delay. By the Lyapunov-Razumikhin method, a novel criterion is proposed to guarantee the global exponential synchronization of the coupled delayed network with distributed impulsive control in terms of matrix inequalities. The sum of coupling strengths of the distributed impulsive control is minimized to save the control effort. Finally, the effectiveness of the proposed method has been demonstrated by some simulations
Dive Deeper into Rectifying Homography for Stereo Camera Online Self-Calibration
Accurate estimation of stereo camera extrinsic parameters is the key to
guarantee the performance of stereo matching algorithms. In prior arts, the
online self-calibration of stereo cameras has commonly been formulated as a
specialized visual odometry problem, without taking into account the principles
of stereo rectification. In this paper, we first delve deeply into the concept
of rectifying homography, which serves as the cornerstone for the development
of our novel stereo camera online self-calibration algorithm, for cases where
only a single pair of images is available. Furthermore, we introduce a simple
yet effective solution for global optimum extrinsic parameter estimation in the
presence of stereo video sequences. Additionally, we emphasize the
impracticality of using three Euler angles and three components in the
translation vectors for performance quantification. Instead, we introduce four
new evaluation metrics to quantify the robustness and accuracy of extrinsic
parameter estimation, applicable to both single-pair and multi-pair cases.
Extensive experiments conducted across indoor and outdoor environments using
various experimental setups validate the effectiveness of our proposed
algorithm. The comprehensive evaluation results demonstrate its superior
performance in comparison to the baseline algorithm. Our source code, demo
video, and supplement are publicly available at mias.group/StereoCalibrator
SpecLLM: Exploring Generation and Review of VLSI Design Specification with Large Language Model
The development of architecture specifications is an initial and fundamental
stage of the integrated circuit (IC) design process. Traditionally,
architecture specifications are crafted by experienced chip architects, a
process that is not only time-consuming but also error-prone. Mistakes in these
specifications may significantly affect subsequent stages of chip design.
Despite the presence of advanced electronic design automation (EDA) tools,
effective solutions to these specification-related challenges remain scarce.
Since writing architecture specifications is naturally a natural language
processing (NLP) task, this paper pioneers the automation of architecture
specification development with the advanced capabilities of large language
models (LLMs). Leveraging our definition and dataset, we explore the
application of LLMs in two key aspects of architecture specification
development: (1) Generating architecture specifications, which includes both
writing specifications from scratch and converting RTL code into detailed
specifications. (2) Reviewing existing architecture specifications. We got
promising results indicating that LLMs may revolutionize how these critical
specification documents are developed in IC design nowadays. By reducing the
effort required, LLMs open up new possibilities for efficiency and accuracy in
this crucial aspect of chip design
RTLLM: An Open-Source Benchmark for Design RTL Generation with Large Language Model
Inspired by the recent success of large language models (LLMs) like ChatGPT,
researchers start to explore the adoption of LLMs for agile hardware design,
such as generating design RTL based on natural-language instructions. However,
in existing works, their target designs are all relatively simple and in a
small scale, and proposed by the authors themselves, making a fair comparison
among different LLM solutions challenging. In addition, many prior works only
focus on the design correctness, without evaluating the design qualities of
generated design RTL. In this work, we propose an open-source benchmark named
RTLLM, for generating design RTL with natural language instructions. To
systematically evaluate the auto-generated design RTL, we summarized three
progressive goals, named syntax goal, functionality goal, and design quality
goal. This benchmark can automatically provide a quantitative evaluation of any
given LLM-based solution. Furthermore, we propose an easy-to-use yet
surprisingly effective prompt engineering technique named self-planning, which
proves to significantly boost the performance of GPT-3.5 in our proposed
benchmark
High genetic abundance of Rpi-blb2/Mi-1.2/Cami gene family in Solanaceae
Relative genomic positions of genes among potato (upper), pepper (middle) and tomato (lower) along chromosome 6. (DOCX 282 kb
RTLCoder: Outperforming GPT-3.5 in Design RTL Generation with Our Open-Source Dataset and Lightweight Solution
The automatic generation of RTL code (e.g., Verilog) using natural language
instructions and large language models (LLMs) has attracted significant
research interest recently. However, most existing approaches heavily rely on
commercial LLMs such as ChatGPT, while open-source LLMs tailored for this
specific design generation task exhibit notably inferior performance. The
absence of high-quality open-source solutions restricts the flexibility and
data privacy of this emerging technique. In this study, we present a new
customized LLM solution with a modest parameter count of only 7B, achieving
better performance than GPT-3.5 on two representative benchmarks for RTL code
generation. This remarkable balance between accuracy and efficiency is made
possible by leveraging our new RTL code dataset and a customized LLM algorithm,
both of which will be made fully open-source. Furthermore, we have successfully
quantized our LLM to 4-bit with a total size of 4GB, enabling it to function on
a single laptop with only slight performance degradation. This efficiency
allows the RTL generator to serve as a local assistant for engineers, ensuring
all design privacy concerns are addressed
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