158 research outputs found
Late Fusion Multi-view Clustering via Global and Local Alignment Maximization
Multi-view clustering (MVC) optimally integrates complementary information
from different views to improve clustering performance. Although demonstrating
promising performance in various applications, most of existing approaches
directly fuse multiple pre-specified similarities to learn an optimal
similarity matrix for clustering, which could cause over-complicated
optimization and intensive computational cost. In this paper, we propose late
fusion MVC via alignment maximization to address these issues. To do so, we
first reveal the theoretical connection of existing k-means clustering and the
alignment between base partitions and the consensus one. Based on this
observation, we propose a simple but effective multi-view algorithm termed
LF-MVC-GAM. It optimally fuses multiple source information in partition level
from each individual view, and maximally aligns the consensus partition with
these weighted base ones. Such an alignment is beneficial to integrate
partition level information and significantly reduce the computational
complexity by sufficiently simplifying the optimization procedure. We then
design another variant, LF-MVC-LAM to further improve the clustering
performance by preserving the local intrinsic structure among multiple
partition spaces. After that, we develop two three-step iterative algorithms to
solve the resultant optimization problems with theoretically guaranteed
convergence. Further, we provide the generalization error bound analysis of the
proposed algorithms. Extensive experiments on eighteen multi-view benchmark
datasets demonstrate the effectiveness and efficiency of the proposed
LF-MVC-GAM and LF-MVC-LAM, ranging from small to large-scale data items. The
codes of the proposed algorithms are publicly available at
https://github.com/wangsiwei2010/latefusionalignment
Outlier Detection Ensemble with Embedded Feature Selection
Feature selection places an important role in improving the performance of
outlier detection, especially for noisy data. Existing methods usually perform
feature selection and outlier scoring separately, which would select feature
subsets that may not optimally serve for outlier detection, leading to
unsatisfying performance. In this paper, we propose an outlier detection
ensemble framework with embedded feature selection (ODEFS), to address this
issue. Specifically, for each random sub-sampling based learning component,
ODEFS unifies feature selection and outlier detection into a pairwise ranking
formulation to learn feature subsets that are tailored for the outlier
detection method. Moreover, we adopt the thresholded self-paced learning to
simultaneously optimize feature selection and example selection, which is
helpful to improve the reliability of the training set. After that, we design
an alternate algorithm with proved convergence to solve the resultant
optimization problem. In addition, we analyze the generalization error bound of
the proposed framework, which provides theoretical guarantee on the method and
insightful practical guidance. Comprehensive experimental results on 12
real-world datasets from diverse domains validate the superiority of the
proposed ODEFS.Comment: 10pages, AAAI202
Multiobjective Optimization Design and Performance Prediction of Centrifugal Pump Based on Orthogonal Test
In order to improve the hydraulic performance of the centrifugal pump, based on the original model, the optimization mathematical model with the four indexes head, efficiency, shaft power, and pump net positive suction head as objective function was established, and the multiobjective optimization design of the centrifugal pump was carried out by orthogonal test. Based on the L1644 orthogonal table, 16 sets of orthogonal test schemes were made by selecting the four parameters impeller outlet width, blade inlet angle, blade outlet angle, and cape angle; the flow field numerical simulation was carried out by computational fluid dynamics technique; and the influence order of geometric parameters on optimization indexes was obtained by range analysis. The weight of each test factor on the optimization index was calculated by weight matrix, and a set of optimal schemes was obtained. Based on the external characteristic experimental bench of the IH 65-60-190 chemical centrifugal pump, the simulation values and test values of the prototype pump and the optimization pump were obtained under different working conditions. Under the rated flow, the head was reduced by 17.00%, the efficiency was increased by 9.14%, the shaft power was reduced by 21.50%, the pump net positive suction head was reduced by 16.69%, the curve hump was eliminated, the performance of centrifugal pump was improved, and the feasibility of the weight matrix optimization method was verified. The particle image velocimetry measurement system was used to measure the relative velocity of the internal media in the centrifugal pump. The results showed that the optimization pump had no obvious “jet-wake” flow structure, its maximum velocity was less than the prototype pump, the area of low-speed zone was larger than the prototype pump, the efficiency of the centrifugal pump was improved, and the shaft power and pump net positive suction head were reduced. The reason of the head decrease was analyzed from the internal flow situation, and the accuracy of the design optimization process was proved
Some hesitant fuzzy geometric operators and their application to multiple attribute group decision making
Hesitant fuzzy set (HFS), a generalization of fuzzy set (FS), permits the membership degree of an element of a set to be represented as several possible values between 0 and 1. In this paper, motivated by the extension principle of HFs, we export Einstein operations on FSs to HFs, and develop some new aggregation operators, such as the hesitant fuzzy Einstein weighted geometric operator, hesitant fuzzy Einstein ordered weighted geometric operator, and hesitant fuzzy Einstein hybrid weighted geometric operator, for aggregating hesitant fuzzy elements. In addition, we discuss the correlations between the proposed aggregation operators and the existing ones respectively. Finally, we apply the hesitant fuzzy Einstein weighted geometric operator to multiple attribute group decision making with hesitant fuzzy information. Some numerical examples are given to illustrate the proposed aggregation operators.
First published online:Â 09 Jun 201
A 0.1–5.0 GHz flexible SDR receiver with digitally assisted calibration in 65 nm CMOS
© 2017 Elsevier Ltd. All rights reserved.A 0.1–5.0 GHz flexible software-defined radio (SDR) receiver with digitally assisted calibration is presented, employing a zero-IF/low-IF reconfigurable architecture for both wideband and narrowband applications. The receiver composes of a main-path based on a current-mode mixer for low noise, a high linearity sub-path based on a voltage-mode passive mixer for out-of-band rejection, and a harmonic rejection (HR) path with vector gain calibration. A dual feedback LNA with “8” shape nested inductor structure, a cascode inverter-based TCA with miller feedback compensation, and a class-AB full differential Op-Amp with Miller feed-forward compensation and QFG technique are proposed. Digitally assisted calibration methods for HR, IIP2 and image rejection (IR) are presented to maintain high performance over PVT variations. The presented receiver is implemented in 65 nm CMOS with 5.4 mm2 core area, consuming 9.6–47.4 mA current under 1.2 V supply. The receiver main path is measured with +5 dB m/+5dBm IB-IIP3/OB-IIP3 and +61dBm IIP2. The sub-path achieves +10 dB m/+18dBm IB-IIP3/OB-IIP3 and +62dBm IIP2, as well as 10 dB RF filtering rejection at 10 MHz offset. The HR-path reaches +13 dB m/+14dBm IB-IIP3/OB-IIP3 and 62/66 dB 3rd/5th-order harmonic rejection with 30–40 dB improvement by the calibration. The measured sensitivity satisfies the requirements of DVB-H, LTE, 802.11 g, and ZigBee.Peer reviewedFinal Accepted Versio
Single-cell Multi-view Clustering via Community Detection with Unknown Number of Clusters
Single-cell multi-view clustering enables the exploration of cellular
heterogeneity within the same cell from different views. Despite the
development of several multi-view clustering methods, two primary challenges
persist. Firstly, most existing methods treat the information from both
single-cell RNA (scRNA) and single-cell Assay of Transposase Accessible
Chromatin (scATAC) views as equally significant, overlooking the substantial
disparity in data richness between the two views. This oversight frequently
leads to a degradation in overall performance. Additionally, the majority of
clustering methods necessitate manual specification of the number of clusters
by users. However, for biologists dealing with cell data, precisely determining
the number of distinct cell types poses a formidable challenge. To this end, we
introduce scUNC, an innovative multi-view clustering approach tailored for
single-cell data, which seamlessly integrates information from different views
without the need for a predefined number of clusters. The scUNC method
comprises several steps: initially, it employs a cross-view fusion network to
create an effective embedding, which is then utilized to generate initial
clusters via community detection. Subsequently, the clusters are automatically
merged and optimized until no further clusters can be merged. We conducted a
comprehensive evaluation of scUNC using three distinct single-cell datasets.
The results underscored that scUNC outperforms the other baseline methods
Surfactant Induced Reservoir Wettability Alteration: Recent Theoretical and Experimental Advances in Enhanced Oil Recovery
Reservoir wettability plays an important role in various oil recovery processes. The origin and evolution of reservoir wettability were critically reviewed to better understand the complexity of wettability due to interactions in crude oil-brine-rock system, with introduction of different wetting states and their influence on fluid distribution in pore spaces. The effect of wettability on oil recovery of waterflooding was then summarized from past and recent research to emphasize the importance of wettability in oil displacement by brine. The mechanism of wettability alteration by different surfactants in both carbonate and sandstone reservoirs was analyzed, concerning their distinct surface chemistry, and different interaction patterns of surfactants with components on rock surface. Other concerns such as the combined effect of wettability alteration and interfacial tension (IFT) reduction on the imbibition process was also taken into account. Generally, surfactant induced wettability alteration for enhanced oil recovery is still in the stage of laboratory investigation. The successful application of this technique relies on a comprehensive survey of target reservoir conditions, and could be expected especially in low permeability fractured reservoirs and forced imbibition process
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