333 research outputs found
T-Crowd: Effective Crowdsourcing for Tabular Data
Crowdsourcing employs human workers to solve computer-hard problems, such as
data cleaning, entity resolution, and sentiment analysis. When crowdsourcing
tabular data, e.g., the attribute values of an entity set, a worker's answers
on the different attributes (e.g., the nationality and age of a celebrity star)
are often treated independently. This assumption is not always true and can
lead to suboptimal crowdsourcing performance. In this paper, we present the
T-Crowd system, which takes into consideration the intricate relationships
among tasks, in order to converge faster to their true values. Particularly,
T-Crowd integrates each worker's answers on different attributes to effectively
learn his/her trustworthiness and the true data values. The attribute
relationship information is also used to guide task allocation to workers.
Finally, T-Crowd seamlessly supports categorical and continuous attributes,
which are the two main datatypes found in typical databases. Our extensive
experiments on real and synthetic datasets show that T-Crowd outperforms
state-of-the-art methods in terms of truth inference and reducing the cost of
crowdsourcing
Local Buckling of Concrete Filled Rectangular Steel Tube with Longitudinal Stiffener under Axial Compression
Width-thickness ratio was an important parameter for designing Concrete Filled Rectangular Steel Tube (CFRST). Welding longitudinal stiffener on the internal wall of steel pipe could delay the local buckling, which increased the limit of width-thickness ratio. If there was not enough stiffener and its sectional dimension was too small, the local buckling of steel pipe would occur, inducing its bearing capacity seriously. If the stiffener sectional dimension was too large, concrete filled in steel tube would be broken up, which reduces its bearing capacity. To solve that problem, this paper studied local buckling of CFRST with longitudinal stiffener under axial compression and design of longitudinal stiffener. It established buckling analysis model, simplified local buckling analysis as calculating buckling load of thin plate clamped on loading side and unloading side under axial force. It deduced buckling load and buckling coefficient based on the principle of energy. The results showed that buckling mode depended on stiffening rigidity. Therefore, it put forward minimum stiffening rigidity ratio that controlled the stiffener design. This paper also came up with a formula to calculate minimum stiffening rigidity ratio. It provided guidance on designing number, sectional dimension and material performance
Hierarchical temperature imaging using pseudoinversed convolutional neural network aided TDLAS tomography
As an in situ combustion diagnostic tool, Tunable Diode Laser Absorption
Spectroscopy (TDLAS) tomography has been widely used for imaging of
two-dimensional temperature distributions in reactive flows. Compared with the
computational tomographic algorithms, Convolutional Neural Networks (CNNs) have
been proofed to be more robust and accurate for image reconstruction,
particularly in case of limited access of laser beams in the Region of Interest
(RoI). In practice, flame in the RoI that requires to be reconstructed with
good spatial resolution is commonly surrounded by low-temperature background.
Although the background is not of high interest, spectroscopic absorption still
exists due to heat dissipation and gas convection. Therefore, we propose a
Pseudo-Inversed CNN (PI-CNN) for hierarchical temperature imaging that (a) uses
efficiently the training and learning resources for temperature imaging in the
RoI with good spatial resolution, and (b) reconstructs the less spatially
resolved background temperature by adequately addressing the integrity of the
spectroscopic absorption model. In comparison with the traditional CNN, the
newly introduced pseudo inversion of the RoI sensitivity matrix is more
penetrating for revealing the inherent correlation between the projection data
and the RoI to be reconstructed, thus prioritising the temperature imaging in
the RoI with high accuracy and high computational efficiency. In this paper,
the proposed algorithm was validated by both numerical simulation and lab-scale
experiment, indicating good agreement between the phantoms and the
high-fidelity reconstructions.Comment: Submitted to IEEE Transactions on Instrumentation and Measuremen
AnycostFL: Efficient On-Demand Federated Learning over Heterogeneous Edge Devices
In this work, we investigate the challenging problem of on-demand federated
learning (FL) over heterogeneous edge devices with diverse resource
constraints. We propose a cost-adjustable FL framework, named AnycostFL, that
enables diverse edge devices to efficiently perform local updates under a wide
range of efficiency constraints. To this end, we design the model shrinking to
support local model training with elastic computation cost, and the gradient
compression to allow parameter transmission with dynamic communication
overhead. An enhanced parameter aggregation is conducted in an element-wise
manner to improve the model performance. Focusing on AnycostFL, we further
propose an optimization design to minimize the global training loss with
personalized latency and energy constraints. By revealing the theoretical
insights of the convergence analysis, personalized training strategies are
deduced for different devices to match their locally available resources.
Experiment results indicate that, when compared to the state-of-the-art
efficient FL algorithms, our learning framework can reduce up to 1.9 times of
the training latency and energy consumption for realizing a reasonable global
testing accuracy. Moreover, the results also demonstrate that, our approach
significantly improves the converged global accuracy.Comment: Accepted to IEEE INFOCOM 202
FAST: Fidelity-Adjustable Semantic Transmission over Heterogeneous Wireless Networks
In this work, we investigate the challenging problem of on-demand semantic
communication over heterogeneous wireless networks. We propose a
fidelity-adjustable semantic transmission framework (FAST) that empowers
wireless devices to send data efficiently under different application scenarios
and resource conditions. To this end, we first design a dynamic sub-model
training scheme to learn the flexible semantic model, which enables edge
devices to customize the transmission fidelity with different widths of the
semantic model. After that, we focus on the FAST optimization problem to
minimize the system energy consumption with latency and fidelity constraints.
Following that, the optimal transmission strategies including the scaling
factor of the semantic model, computing frequency, and transmitting power are
derived for the devices. Experiment results indicate that, when compared to the
baseline transmission schemes, the proposed framework can reduce up to one
order of magnitude of the system energy consumption and data size for
maintaining reasonable data fidelity.Comment: 6 pages, 4 figures. Accepted by ICC 202
Knowing What LLMs DO NOT Know: A Simple Yet Effective Self-Detection Method
Large Language Models (LLMs) have shown great potential in Natural Language
Processing (NLP) tasks. However, recent literature reveals that LLMs generate
nonfactual responses intermittently, which impedes the LLMs' reliability for
further utilization. In this paper, we propose a novel self-detection method to
detect which questions that a LLM does not know that are prone to generate
nonfactual results. Specifically, we first diversify the textual expressions
for a given question and collect the corresponding answers. Then we examine the
divergencies between the generated answers to identify the questions that the
model may generate falsehoods. All of the above steps can be accomplished by
prompting the LLMs themselves without referring to any other external
resources. We conduct comprehensive experiments and demonstrate the
effectiveness of our method on recently released LLMs, e.g., Vicuna, ChatGPT,
and GPT-4
Truth Inference in Crowdsourcing: Is the Problem Solved?
Crowdsourcing has emerged as a novel problem-solving paradigm, which facilitates addressing problems that are hard for computers, e.g., entity resolution and sentiment analysis. However, due to the openness of crowdsourcing, workers may yield low-quality answers, and a redundancy-based method is widely employed, which first assigns each task to multiple workers and then infers the correct answer (called truth) for the task based on the answers of the assigned workers. A fundamental problem in this method is Truth Inference, which decides how to effectively infer the truth. Recently, the database community and data mining community independently study this problem and propose various algorithms. However, these algorithms are not compared extensively under the same framework and it is hard for practitioners to select appropriate algorithms. To alleviate this problem, we provide a detailed survey on 17 existing algorithms and perform a comprehensive evaluation using 5 real datasets. We make all codes and datasets public for future research. Through experiments we find that existing algorithms are not stable across different datasets and there is no algorithm that outperforms others consistently. We believe that the truth inference problem is not fully solved, and identify the limitations of existing algorithms and point out promising research directions
Dynamic behaviour of prestressed concrete beams considering moving loads
U ovom se radu ispituje pravilo dinamiÄkog odziva prednapetih betonskih greda s metalnim i plastiÄnim valovitim cijevima razliÄitih vrijednosti kompaktnosti injekcijske smjese kanala na pokretna konstantna koncentrirana optereÄenja i pokretna jednostavna harmonijska optereÄenja. Prednapete betonske grede s metalnim i plastiÄnim valovitim cijevima analizirane su metodom konaÄnih elemenata u sluÄajevima bez pukotina. Rezultati pokazuju da kompaktnost injekcijske smjese kanala i materijal za oblikovanje utjeÄu na karakteristike prirodnih vibracija prednapetih betonskih greda. Pod istom kompaktnoÅ”Äu injekcijske smjese kanala, prednapete betonske grede s metalnim valovitim cijevima pokazuju veÄe frekvencije u usporedbi s onima koja imaju plastiÄe valovite cijevi. DinamiÄki progib prednapetih betonskih greda u sredini raspona smanjuje se s poveÄanjem kompaktnosti injekcijske smjese kanala, Å”to je neovisno o materijalu za oblikovanje. Razlike u brzini i ubrzanju srednjeg raspona uzrokovane pokretnim optereÄenjem izmeÄu prednapetih betonskih greda metalnih i plastiÄnih valovitih cijevi su male. To pokazuje da materijal koji stvara pore ima mali uÄinak na brzinu Ävora u sredini raspona i reakciju ubrzanja prednapetih betonskih greda.with different duct grouting compactness values under moving constant concentrated loads and moving simple harmonic loads is studied. Prestressed concrete beams with metal and plastic corrugated pipes are analysed using the finite element method for the case of non-cracking. The results indicate that duct grouting compactness and forming material affect the natural vibration characteristics of prestressed concrete beams. Under identical duct grouting compactness, prestressed concrete beams with metal corrugated pipes exhibit higher frequencies compared with those with plastic corrugated pipes. The mid-span dynamic deflection of the prestressed concrete beams decreases with an increase in duct grouting compactness, which is independent of the forming material. The differences in the midspan speed and acceleration caused by the moving loads between the corrugated duct prestressed concrete beams made of metal and those made of plastic are small; this indicates that the pore-forming material has little effect on the midspan node speed and acceleration response of prestressed concrete beams
- ā¦