A Novel Approach for Bolted T-Stub Connections

This paper reports an investigation into new connection types and their behaviors determined using full-scale experiments. T-shaped connections were created using the IPE standard profile. The aim of this study was to analyze the influence of T connections based on the IPE standard profile, height of beam to height of T-stub joint (H) of T-stub joints, and lengths (X) of T-stub joints on the behavior of steel connections, in order to provide the necessary data for improving Eurocode 3 and enable efficient use of residue IPE standard profiles and back to the consumption cycle. While the moment resistance values increased with an increase in H from H_min to H_max in model groups with X of 126 mm, and the energy dissipation increased with an increase in H from H_min to H_max and also with an increase in the lengths (X) of T-stub joints from 54 to 126 mm.     

Post-fire behavior of CFRP retrofitted thin-walled steel tanks

Thin-walled shell structures are characterized by a lightweight structural form with high strength. This structure has many applications in various engineering fields and is considered to be a basic tool in the modern industry. This study investigates the effect of CFRP on tanks after post-fire in order to examine the buckling and post-buckling of the cylindrical tanks. Herein, post-fire was introduced at different temperatures (150°C-600°C). Ten laboratory specimens in two groups with verified temperatures, under external pressure, are examined. The models were designed to demonstrate how repairing steel tanks, which are damaged by fire, by using carbon-fiber-reinforced polymer can recover lost capacity. The results of testing under different theories and codes were compared. This study shows that the initial buckling load of the temperature group increased by 30.82% to 57.09% compared to the temperature without-CFRP group. The overall buckling load of the temperature group increased by 37.01% to 67.74% compared to the temperature without-CFRP group. The collapse load of the temperature group increased by 27.04% to 52.64% compared to the temperature without-CFRP group. And using carbon-fiber-reinforced polymer on models, which are damaged by fire, can be an improvement behavior for the buckling and post-buckling specimen tests.     

Measurement of slip length on superhydrophobic surfaces

In this paper, a review of different techniques used to measure the slip length on superhydrophobic surfaces with large slip length is presented. First, we present the theoretical models used to calculate the effective slip length on superhydrophobic surfaces in different configurations of liquid flow. Then, we present the different techniques used to measure the slip past these superhydrophobic surfaces: rheometry, particle image velocimetry, pressure drop, surface force apparatus and atomic force microscopy.     

A cooperative Bayesian and lower bound estimation in dynamic framed slotted ALOHA algorithm for RFID systems

A novel estimation scheme that combines Bayesian and lower bound estimating radio frequency identification tag population size is proposed. The developed methodology is based on the fusion between the Bayesian and lower bound estimating techniques. It turns out that the fusion rule is built up thanks to an existing linear relationship between the cited techniques. Simulation results show that the developed technique significantly improves the accuracy of the estimating tag quantity and presents less estimation error. Also, the resulting advanced dynamic framed slotted ALOHA protocol considerably improves the performance and efficiency of the radio frequency identification anti‐collision compared with the most recent protocols using others estimating methods.     

A robust auto‐adaptive approach for serial acquisition of generalized multi‐carrier spread spectrum in multipath fading mobile channels

In this paper, a new robust auto‐adaptive approach for pseudo‐noise (PN) code acquisition is proposed. It is applied to the generalized multi‐carrier direct‐sequence code‐division multiple‐access (MC DS‐CDMA) systems communicating over frequency‐selective multipath Rayleigh fading channels. This new approach is based on the constant false alarm rate (CFAR) detection algorithm, referred here as automatic selection partial sum ordered statistics (ASPSOS)‐CFAR. The proposed approach does not require any prior information about the background environment and uses maximum likelihood estimation (MLE) method to detect the interfering signals group in the ranked cells for the full reference window. Once this group is identified and censored, the remaining smaller ranked cells are combined to form an estimate of the background noise level to compute the adaptive threshold. Through simulations, the performance of the proposed detector is analyzed and compared with traditional CFAR detectors based on fixed or automatic censoring algorithms. The obtained results show that the proposed detector eliminates the drawbacks of the previously related detectors and offers a robust detection performance to enhance the acquisition process in heterogeneous background environments.     

An efficient and lightweight multi‐scroll chaos‐based hardware solution for protecting fingerprint biometric templates

This paper presents a new efficient and lightweight approach for enhancing the security of biometric models, namely, fingerprint templates, against possible attacks. The proposed design is based on Vernam stream cipher in which the key generator is designed in the hardware manner. The designed cryptosystem consists of using multi‐scroll chaotic system that is characterized by a large key space and can be generated N×N grid multi‐scroll attractors, with a good behavior of chaotic dynamic. The hardware approach is carried out through describing Euler method by VHDL. Field‐programmable gate array (FPGA) experimental results validate the developed architecture while still providing a good compromise between hardware resources and performance. Indeed, security analysis also shows that the designed encryption algorithm is robust against statistical, brute force, and entropy attacks. Therefore, it can be considered as a lightweight security solution, which could be very useful in many embedded applications namely securing biometric authentication systems.     

A strategy toward spectral and colorimetric color reproduction using ordinary digital cameras

In this work, a methodology is introduced to use ordinary digital RGB cameras for the purpose of spectral and colorimetric color reproduction. First, it is attempted to recover the spectral reflectance from RGB camera response using different approaches, among which, it is shown that weighted nonlinear regression as performed better than other approaches. After analyzing the results, it is realized that although spectrally the results are satisfactory, there is still a significant colorimetric error left, that should be addressed. Therefore, in the second part of the article, different linear and nonlinear matrix transforms are used to change the RGB camera response to CIEXYZ tristimulus values under a specific condition. It is concluded that colorimetric error of the recovery can be reduced significantly when a separate path is used for colorimetric color reproduction.     

Multimedia document retrieval using speech and speaker recognition

Speech and speaker recognition systems are rapidly being deployed in real-world applications. In this paper, we discuss the details of a system and its components for indexing and retrieving multimedia content derived from broadcast news sources. The audio analysis component calls for real-time speech recognition for converting the audio to text and concurrent speaker analysis consisting of the segmentation of audio into acoustically homogeneous sections followed by speaker identification. The output of these two simultaneous processes is used to abstract statistics to automatically build indexes for text-based and speaker-based retrieval without user intervention. The real power of multimedia document processing is the possibility of Boolean queries in the form of combined text- and speaker-based user queries. Retrieval for such queries entails combining the results of individual text and speaker based searches. The underlying techniques discussed here can easily be extended to other speech-centric applications and transactions.     

Optimal eigenvectors of spectral datasets: sequential selection from one set vs a collection from two sets

In this paper, the influence of spectral datasets and the method of selection of the corresponding feature vectors on the compression and reconstruction of data is scrutinised. To fulfil this aim, two different sets of reflectance data with the least spectral similarity are selected from different sets of spectral databases and the most optimal eigenvectors are chosen using different strategies. Six and 12 arrangements of eigenvectors obtained from different individual or combined databases are then used for the compression of reflectance spectra of learning sets, as well as those that have not been used in extraction of eigenvectors. The validity of the desired reduced subspaces is assessed by computing the spectral errors between the actual and the reconstructed spectra of samples of learning sets. Moreover, the efficiencies of designed compressed subspaces are evaluated through the numbers of out‐of‐range reconstructed spectra, as well as the spectral and colorimetric deviations between the actual and compressed‐reconstructed reflectance spectra of samples of datasets that were not employed in learning sequence. The results show that in the restricted subspaces, i.e. six‐dimensional subspace, the most effective results are achieved when the reduced subspace is created from a collection of two separate sets of eigenvectors of two different datasets with the maximum degree of dissimilarity, and the reduced spaces that have been made from six eigenvectors of individual datasets lead to higher errors.