101 research outputs found
Synergistic Co-Pyrolysis of Biomass and Natural Gas over HZSM-5 Catalysts
Bio-oil produced from pyrolysis of lignocellulose biomass is regarded as a potential intermediate to synthesize renewable hydrocarbon fuels and chemicals. However, the utilization of bio-oil has been challenged by undesirable attributes associated with its high oxygen content. The current study is focused on effective technologies that address the issues with unwanted properties of bio-oil and result in a product that is compatible to the current refinery infrastructures in long term. The mechanisms that lead to unstable properties of bio-oil during storage and recent developments on methods to improve storage stability of bio-oil were reviewed in Chapter 1. The pyrolytic behavior of eastern redcedar wood, an invasive plant in Oklahoma was investigated in Chapter 2. Results showed that pyrolysis conditions, such as reaction temperature and heating rate, and feedstock wood zones (heartwood and sapwood) had significant effects on the distribution and composition of pyrolysis products. In addition, alpha/beta-cedrene, a high-value product extracted from slow pyrolysis of eastern redcedar, was in higher amount from heartwood than from sapwood. Torrefied switchgrass (Chapter 3) yielded a higher H/C ratio and lower O/C ratio. Torrefaction enhanced the production of sugar-based compounds and phenols during pyrolysis. Densification enhanced the degradation of carbohydrate components in biomass feedstock thus yielded more secondary pyrolysis products, such as furans, ketones and acetic acids. Methane incorporated into the hydrodeoxygenation of lignin-derived phenols and increased the aromatics yield (Chapter 4). Molybdenum modified HZSM-5 catalysts were found to promote deoxygenation of lignin-derived phenols, resulting in more simple aromatics. In Chapter 5, catalysis of torrefied switchgrass with the intervention of methane was performed in presence of molybdenum modified bimetallic catalysts, MoAg/HZSM-5 and MoZn/HZSM-5. Bimetallic loading catalysts demonstrated a higher reactivity towards methane activation. The maximum aromatic carbon yield of 39.31 % was achieved from catalysis of raw switchgrass under methane atmosphere over MoZn/HZSM-5 at 700°C. Torrefaction had no significant effect in improving the yield of aromatics from catalysis due to the loss of cellulose and concentration of lignin during torrefaction process. Catalysis of biomass with the intervention of cheap methane is a promising biomass upgrading technology.Biosystems and Agricultural Engineerin
Automatic Emotion-specific Effects of Emotion-Representations on Agency Appraisals
Master'sMASTER OF SOCIAL SCIENCE
Exploring Intra- and Inter-Video Relation for Surgical Semantic Scene Segmentation
Automatic surgical scene segmentation is fundamental for facilitating
cognitive intelligence in the modern operating theatre. Previous works rely on
conventional aggregation modules (e.g., dilated convolution, convolutional
LSTM), which only make use of the local context. In this paper, we propose a
novel framework STswinCL that explores the complementary intra- and inter-video
relations to boost segmentation performance, by progressively capturing the
global context. We firstly develop a hierarchy Transformer to capture
intra-video relation that includes richer spatial and temporal cues from
neighbor pixels and previous frames. A joint space-time window shift scheme is
proposed to efficiently aggregate these two cues into each pixel embedding.
Then, we explore inter-video relation via pixel-to-pixel contrastive learning,
which well structures the global embedding space. A multi-source contrast
training objective is developed to group the pixel embeddings across videos
with the ground-truth guidance, which is crucial for learning the global
property of the whole data. We extensively validate our approach on two public
surgical video benchmarks, including EndoVis18 Challenge and CaDIS dataset.
Experimental results demonstrate the promising performance of our method, which
consistently exceeds previous state-of-the-art approaches. Code will be
available at https://github.com/YuemingJin/STswinCL
Evaluation of the Pacific oyster marine aquaculture suitability in Shandong, China based on GIS and remote sensing
The Pacific oyster (Crassostrea gigas) is a marine aquaculture species with rapid production growth in recent years. China accounts for nearly 90% of global production by 2021, especially in Shandong province. Evaluating suitability is crucial for ensuring the sustainable growth of Pacific oyster marine aquaculture and achieving a blue transition. This study developed a suitability evaluation model for Pacific oyster marine aquaculture using a Geographic Information System (GIS), Maximum Entropy (MaxEnt) model, remote sensing, and reanalysis data. A literature review and Analytic Hierarchy Process (AHP) were used to establish an evaluation model encompassing water quality, hydrology, climate and meteorology, and socioeconomic factors. The results showed that within a 20 km range of the Shandong coast, 49% of the area was highly suitable, 51% was moderately suitable, and the overall annual high score proportion (HSP) fluctuated around 50%, with higher suitability observed in the spring and autumn. The inner bays of the coastal areas (Laizhou, Rongcheng, Jimo) exhibited high suitability (HSP over 80%); in contrast, the offshore areas (Changdao, Rushan) farther from the coast had lower suitability and showed significant monthly variations. The result was consistent with the spatial distribution and temporal variation of Shandong’s existing Pacific oyster marine aquaculture areas. The study also found that El Niño significantly impacts Rongcheng, Rushan, and Jimo during summer. We predicted an overall increase of suitability in the Shandong offshore areas under future climate change scenarios, with a more significant increase of suitability in the north. El Niño-Southern Oscillation (ENSO) influenced the concentration of parameters such as chlorophyll-a (Chl-a) and total suspended sediment (TSS) in the coastal waters through its impact on precipitation (Pr), resulting in suitability fluctuations
Special Libraries, January 1930
Volume 21, Issue 1https://scholarworks.sjsu.edu/sla_sl_1930/1000/thumbnail.jp
Advancing Transformer Architecture in Long-Context Large Language Models: A Comprehensive Survey
Transformer-based Large Language Models (LLMs) have been applied in diverse
areas such as knowledge bases, human interfaces, and dynamic agents, and
marking a stride towards achieving Artificial General Intelligence (AGI).
However, current LLMs are predominantly pretrained on short text snippets,
which compromises their effectiveness in processing the long-context prompts
that are frequently encountered in practical scenarios. This article offers a
comprehensive survey of the recent advancement in Transformer-based LLM
architectures aimed at enhancing the long-context capabilities of LLMs
throughout the entire model lifecycle, from pre-training through to inference.
We first delineate and analyze the problems of handling long-context input and
output with the current Transformer-based models. We then provide a taxonomy
and the landscape of upgrades on Transformer architecture to solve these
problems. Afterwards, we provide an investigation on wildly used evaluation
necessities tailored for long-context LLMs, including datasets, metrics, and
baseline models, as well as optimization toolkits such as libraries,
frameworks, and compilers to boost the efficacy of LLMs across different stages
in runtime. Finally, we discuss the challenges and potential avenues for future
research. A curated repository of relevant literature, continuously updated, is
available at https://github.com/Strivin0311/long-llms-learning.Comment: 40 pages, 3 figures, 4 table
Correlated spectro-polarimetric study along the Z track in XTE J1701-462 puts constraints on its coronal geometry
Context. In September 2022, the transient neutron star low-mass X-ray binary
XTE J1701-462 went into a new outburst. Aims. The objective of this work is to
examine the evolution of the accretion geometry of XTE J1701-462 by studying
the spectro-polarimetric properties along the Z track of this source. The
simultaneous observations archived by the Insight-Hard X-ray Modulation
Telescope (HXMT) and the Imaging X-ray Polarimetry Explorer (IXPE) give us the
opportunity. Methods. We present a comprehensive X-ray spectro-polarimetric
analysis of XTE J1701-462, using simultaneous observations from IXPE,
Insight-HXMT and NuSTAR. For IXPE observations, two methods are employed to
measure the polarization: a model-independent measurement with PCUBE and a
model-dependent polarization-spectral analysis with XSPEC. The corresponding
spectra from Insight-HXMT and NuSTAR are studied with two configurations that
correspond to a slab-like corona and a spherical shell-like corona,
respectively. Results. Significant polarization characteristics are detected in
XTE J1701-462. The polarization degree shows a decreasing trend along the Z
track, reducing from (4.84 0.37)% to (3.76 0.43)% on the horizontal
branch and jumping to less than 1% on the normal branch. The simultaneous
spectral analysis from Insight-HXMT and NuSTAR suggests that the redistribution
between the thermal and Comptonized emission could be the reason for the PD
evolution along the Z track. Based on the correlated spectro-polarimetric
properties, we propose that this source likely has a slab coronal geometry and
the size/thickness of the corona decreases along the Z track
Evaluating how lodging affects maize yield estimation based on UAV observations
Timely and accurate pre-harvest estimates of maize yield are vital for agricultural management. Although many remote sensing approaches have been developed to estimate maize yields, few have been tested under lodging conditions. Thus, the feasibility of existing approaches under lodging conditions and the influence of lodging on maize yield estimates both remain unclear. To address this situation, this study develops a lodging index to quantify the degree of lodging. The index is based on RGB and multispectral images obtained from a low-altitude unmanned aerial vehicle and proves to be an important predictor variable in a random forest regression (RFR) model for accurately estimating maize yield after lodging. The results show that (1) the lodging index accurately describes the degree of lodging of each maize plot, (2) the yield-estimation model that incorporates the lodging index provides slightly more accurate yield estimates than without the lodging index at three important growth stages of maize (tasseling, milking, denting), and (3) the RFR model with lodging index applied at the denting (R5) stage yields the best performance of the three growth stages, with R2 = 0.859, a root mean square error (RMSE) of 1086.412 kg/ha, and a relative RMSE of 13.1%. This study thus provides valuable insight into the precise estimation of crop yield and demonstra\tes that incorporating a lodging stress-related variable into the model leads to accurate and robust estimates of crop grain yield
The First Polarimetric View on Quasi-Periodic Oscillations in a Black Hole X-ray Binary
We present the first polarimetric analysis of Quasi-Periodic Oscillations
(QPO) in a black hole binary utilizing \textit{IXPE} data. Our study focuses on
Swift J1727.8--1613, which experienced a massive outburst that was observed by
various telescopes across different wavelengths. The \textit{IXPE} observation
we studied was conducted during the Hard-Intermediate state. The polarization
degree (PD) and polarization angle (PA) were measured at 4.280.20\% and
, respectively. Remarkably, significant QPO signals
were detected during this observation, with a QPO frequency of approximately
1.34 Hz and a fractional root-mean-square (RMS) amplitude of about 12.3\%.
Furthermore, we conducted a phase-resolved analysis of the QPO using the
Hilbert-Huang transform technique. The photon index showed a strong modulation
with respect to the QPO phase. In contrast, the PD and PA exhibit no
modulations in relation to the QPO phase, which is inconsistent with the
expectation of the Lense-Thirring precession of the inner flow. Further
theoretical studies are needed to conform with the observational results.Comment: Accepted for publication in APJ
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