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排序方式: 共有411条查询结果,搜索用时 13 毫秒
71.
Riaz Uddin Mondal Tapani Ristaniemi Jussi Turkka 《International Journal of Wireless Information Networks》2017,24(4):413-423
Wireless Local Area Network (WLAN) positioning has become a popular localization system due to its low-cost installation and widespread availability of WLAN access points. Traditional grid-based radio frequency (RF) fingerprinting (GRFF) suffers from two drawbacks. First it requires costly and non-efficient data collection and updating procedure; secondly the method goes through time-consuming data pre-processing before it outputs user position. This paper proposes Cluster-based RF Fingerprinting (CRFF) to overcome these limitations by using modified Minimization of Drive Tests data which can be autonomously collected by cellular operators from their subscribers. The effect of environmental changes and device variation on positioning accuracy has been carried out. Experimental results show that even under these variations CRFF can improve positioning accuracy by 15.46 and 22.30% in 95 percentile of positioning error as compared to that of GRFF and K-nearest neighbour methods respectively. 相似文献
72.
Khalil Khan Rehan Ullah Khan Jehad Ali Irfan Uddin Sahib Khan Byeong-hee Roh 《计算机、材料和连续体(英文)》2021,68(3):3483-3498
Race classification is a long-standing challenge in the field of face image analysis. The investigation of salient facial features is an important task to avoid processing all face parts. Face segmentation strongly benefits several face analysis tasks, including ethnicity and race classification. We propose a race-classification algorithm using a prior face segmentation framework. A deep convolutional neural network (DCNN) was used to construct a face segmentation model. For training the DCNN, we label face images according to seven different classes, that is, nose, skin, hair, eyes, brows, back, and mouth. The DCNN model developed in the first phase was used to create segmentation results. The probabilistic classification method is used, and probability maps (PMs) are created for each semantic class. We investigated five salient facial features from among seven that help in race classification. Features are extracted from the PMs of five classes, and a new model is trained based on the DCNN. We assessed the performance of the proposed race classification method on four standard face datasets, reporting superior results compared with previous studies. 相似文献
73.
Mubbshir Saleem Razieh Rafieenia Jalal Uddin Maria Cristina Lavagnolo 《International Journal of Hydrogen Energy》2021,46(40):20871-20881
This study investigates the performance and hidden hydrogen consuming metabolic pathways of a fermentative side stream dynamic membrane (DM) bioreactor using flux balance analysis (FBA). The bioreactor was inoculated with untreated methanogenic seed sludge. It was found that fouling rate aggravated with increasing COD concentration (10–30 g/L) and was positively correlated to it rather than to the applied solid flux on the DM module. Due to increased fouling rate the hydraulic retention time (HRT) could not be reduced less than 0.82 ± 0.02 d. An increase in the organic loading rate (OLR) led to an increase in H2 yield from 0.01 to 0.76 mol H2/mol of sucrose. FBA revealed that homoacetogenesis was the main H2-consuming pathway at lower OLRs (corresponding to 10 and 15 g COD/L), while for the OLR corresponding to 30 g COD/L, homoacetogens were suppressed. More importantly, caproic acid production pathway was identified for the first time as another H2-consuming pathway at high OLR which was not significant at lower OLRs during fermentative dynamic membrane bioreactor operations. 相似文献
74.
N. Habibi S. Uddin F. Al-Salameen S. Al-Amad V. Kumar M. Al-Otaibi N. Abdul Razzack A. Shajan F. Shirshikar 《Indoor air》2021,31(6):1815-1825
The role of airborne particles in the spread of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is well explored. The novel coronavirus can survive in aerosol for extended periods, and its interaction with other viral communities can cause additional virulence and infectivity. This baseline study reports concentrations of SARS-CoV-2, other respiratory viruses, and pathogenic bacteria in the indoor air from three major hospitals (Sheikh Jaber, Mubarak Al-Kabeer, and Al-Amiri) in Kuwait dealing with coronavirus disease 2019 (COVID-19) patients. The indoor aerosol samples showed 12–99 copies of SARS-CoV-2 per m3 of air. Two non-SARS-coronavirus (strain HKU1 and NL63), respiratory syncytial virus (RSV), and human bocavirus, human rhinoviruses, Influenza B (FluB), and human enteroviruses were also detected in COVID-positive areas of Mubarak Al Kabeer hospital (MKH). Pathogenic bacteria such as Mycoplasma pneumonia, Streptococcus pneumonia and, Haemophilus influenza were also found in the hospital aerosols. Our results suggest that the existing interventions such as social distancing, use of masks, hand hygiene, surface sanitization, and avoidance of crowded indoor spaces are adequate to prevent the spread of SARS-CoV-2 in enclosed areas. However, increased ventilation can significantly reduce the concentration of SARS-CoV-2 in indoor aerosols. The synergistic or inhibitory effects of other respiratory pathogens in the spread, severity, and complexity of SARS-CoV-2 need further investigation. 相似文献
75.
Prashanta Dutta Raisuddin Khan Md. Abdus Salam Akanda Md. Wahhaj Uddin Md. 《International Journal of Pressure Vessels and Piping》1997,72(3):203-218
The stability of a toroidal pipe-reducer system is determined here from the solution of non-linear governing equations of axisymmetric deformations of shells of revolution. Numerical solutions are obtained by a modified version of the computer program developed by Uddin for solving the governing equations of axisymmetric shells by the multisegment method of integration. The interpretation of instability of the toroidal reducers is based on Thompson's theorems I and II. Critical pressures for the toroidal reduers are calculated over useful ranges of the curvature ratio, the thickness ratio, and the diameter ratio. It has been found that the critical pressure of these reducers varies almost linearly with the diameter ratio and that the long toroidal reducers are prone to local instability near the larger end. But this critical zone occurs near either one of the two ends as the reducer becomes shorter. The results of stability and stress analysis of toroidal pipe-reducers are compared here with those of conical reducers obtained by Ali and parabolic reducers obtained by Rahman. Comparison shows that toroidal reducers develop uniform stresses of lower magnitude compared to the other two. Further, toroidal reducers are found to sustain higher critical pressure than parabolic reducers except at higher diameter ratio. 相似文献
76.
In this paper we present three models for the behavior of software failures. By applying these models an attempt has been made to predict reliability growth by predicting failure rates and mean time to next failure of software with Weibull inter failure times at different stages. The changes in the performance of the software as a result of the error removal are described as a Bayes empirical-Bayes prediction in Model I. Model II considers a fully Bayesian analysis with non informative priority of Weibull parameters. An approximation due to Lindley is used in this model as the expressions do not appear in close forms. The M.L. approach is used in Model III. Finally we apply these three models to actual failure data and compare their predictive performances. The comparison of the proposed models is also made in terms of the ratio of likelihoods of observed values based on their predictive distributions.
Among these three models, Model I seems to be quite reasonable as it shows higher reliability growth in all stages. It is noted that this model may be useful to measure the current reliability at any particular stage of the testing process and viewed as a measure of software quality. 相似文献
77.
LC Platanias S Uddin P Domanski OR Colamonici 《Canadian Metallurgical Quarterly》1996,271(39):23630-23633
All Type I interferons (IFNalpha, IFNbeta, IFNomega) bind to the Type I IFN receptor (IFNR) and elicit a common set of signaling events, including activation of the Jak/Stat and IRS pathways. However, IFNbeta selectively induces the association of the alpha subunit of the Type I IFNR with p100, a tyrosyl phosphoprotein, to transduce IFNbeta-specific signals. Using antibodies raised against the different components of the Type I IFNR, we identified p100 as the long form of the beta subunit (betaL subunit) of the Type I IFNR. This was also confirmed in experiments with mouse L-929 cells transfected with truncated forms of betaL. Thus, IFNbeta stimulation of human cells or mouse L-929 transfectants expressing the human alpha and betaL subunits, selectively induces the formation of a signaling complex containing the alpha and betaL subunits of the receptor. The IFNbeta-regulated interaction of the alpha and betaL chains is rapid and transient and follows a similar time course with the tyrosine phosphorylation of these receptor components. These data demonstrate that the signaling specificity for different Type I IFNs is established early in the signaling cascade, at the receptor level, and results from distinct interactions between components of the Type I IFNR. 相似文献
78.
Aadil Raza Salman Ghafoor Muhammad Fasih Uddin Butt 《Photonic Network Communications》2018,35(2):265-273
Design of a low-cost fiber–wireless communication architecture is desirable by network operators. Therefore, we demonstrate the transmission of \(2 \times 2\) MIMO spatial streams, each having 2 Gbps DPSK signal to two different radio access units (RAUs) in a distributed antenna system architecture. The proposed architecture employs mode group division multiplexing in combination with wavelength division multiplexing to transport RF DPSK signals centered at 10 GHz. The RF signals are used to modulate optical carriers that are centered at 1300 nm and transmitted toward the RAUs over perfluorinated graded-index plastic optical fiber. Heterodyne detection is performed at the RAUs to transmit mm-wave signals at 60 GHz to the end users. Furthermore, wireline access is also achieved at each RAU to support simplex services. A cost-efficient multiple wavelength source is generated from a single laser by employing a dual-drive Mach–Zehnder modulator. An increase in multiplexing gain is achieved using the two LP modes, LP01 and LP11, of each generated wavelength. The proposed architecture gives acceptable BER results for practical implementation. 相似文献
79.
As time is progressing, the number and the complexity of methods adopted for launching distributed denial of service (DDoS) attacks are changing. Therefore, we propose a methodology for the development of a generalized machine learning (ML)-based model for the detection of DDoS attacks. After exploring various attributes of the dataset chosen for this study, we propose an integrated feature selection (IFS) method which consists of three stages and integration of two different methods, that is, filter and embedded methods to select features which highly contribute to the detection of various types of DDoS attacks. We use light gradient boosting machine (LGBM) algorithm for training of the model for classification of benign and malicious flows. For ensuring satisfactory performance and generalized behavior of the developed model, we test it by passing records of unseen DDoS attack types. Several performance metrics are employed for the evaluation of the model. By comparing the performance of developed model against state-of-the-art models, we state an improvement of around 20% for almost all the reported metrics. We also show that the performance of the model improves if feature space is reduced by 77%. Furthermore, the generalized behavior of the developed model is justified by demonstrating a trade-off between high variance and high bias ML models. 相似文献
80.
Shohag Md. Bodhroddoza Hossain Md. Sayed Hasan Md. Rakibul Ahmed Md. Mobasher Al Mahmud Abdullah Uddin Mohammad Mezbah Soner Md. Abdul Malek Haque Ashraful Khan Kamrul Alam 《Microsystem Technologies》2022,28(12):2785-2793
Microsystem Technologies - Bangladesh Atomic Energy Commission TRIGA Research Reactor (BTRR) is a MK II type nuclear research reactor with a maximum thermal output power of 3 MW. Nuclear... 相似文献