Search results for "communications"

Relay selection in FDD amplify-and-forward cooperative networks

2017

In this paper, the problems of relay selection and distributed beamforming are investigated for bi-directional dual-hop amplify-and-forward frequency-division duplex cooperative wireless networks. When using individual per-relay maximum transmission power constraint, it has been proven that the relay selection and beamforming optimization problem becomes NP hard and requires exhaustive search to find the optimal solution. Therefore, we propose a computationally affordable sub-optimal multiple relay selection and beamforming optimization scheme based on the l1 norm squared relaxation. The proposed scheme performs the selection for the two transmission directions, simultaneously, while aiming…

Coordination in a multi-cell multi-antenna multi-user W-CDMA system: a beamforming approach

2008

The problem of designing joint power control and optimal beamforming (JPCOB) algorithms for the downlink of a coordinated multi-cell WCDMA system is considered throughout this paper. In this case, the JPCOB design is formulated as the problem of minimizing the total transmitted power in the coordinated multi-cell system, subject to a certain quality of service requirement for each user. In this paper, the performance of two JPCOB algorithms based on different beamforming approaches is compared over the coordinated multi-cell system. The first one, obtains local beamformers by means of the well-known virtual uplink-downlink duality. In contrast, the second algorithm implements multi-base bea…

Stochastic Collaborative Beamforming in Wireless Sensor Networks

2018

Wireless Sensor Networks (WSNs) are composed of spatially distributed autonomous sensor devices, named motes. These devices are constituted by a microcontroller, sensors, and they have the ability to communicate in the ISM frequency band using the IEEE 802.15.4 standard. They have their own power supply, AA or AAA batteries, processing unit, sensors and wireless communications. Usually, the motes exchange packets using a multihop routing, and the maximum communication distance emitter-receiver is around 100m. At least one mote acts as a gateway, and the data gathered by the sensors of each mote have to be sent to this mote that is named sink or Base Station (BS). In a WSN the BS is within t…

Electrochemical Synthesis of Fluorinated Orthoesters from 1,3‐Benzodioxoles

2019

Abstract Invited for this month's cover picture is the group of Professor Siegfried Waldvogel. The cover picture displays the robustness achieved by the installation of fluorinated alcohols on 1,3‐benzodioxoles, protecting the obtained orthoesters against acids and bases, like the shield of a knight. The simple protocol allows access to interesting compounds, whose lipophilicity is tremendously increased by the incorporation of fluorinated groups. This makes it possible to adjust the physicochemical properties of the biologically active 1,3‐benzodioxole motif. The surprisingly high stability against acids and bases gives rise to subsequent functionalizations or direct application in medicin…

The Datafication of Hate: Expectations and Challenges in Automated Hate Speech Monitoring.

2020

Laaksonen, S-M.; Haapoja, J.; Kinnunen, T., Nelimarkka, M. & Pöyhtäri, R. (2020, accepted). . Frontiers in Big Data: Data Mining and Management / Critical Data and Algorithm Studies. doi:10.3389/fdata.2020.00003 Hate speech has been identified as a pressing problem in society and several automated approaches have been designed to detect and prevent it. This paper reports and reflects upon an action research setting consisting of multi-organizational collaboration conducted during Finnish municipal elections in 2017, wherein a technical infrastructure was designed to automatically monitor candidates' social media updates for hate speech. The setting allowed us to engage in a 2-fold investiga…

Local Directional Multi Radius Binary Pattern

2018

Face recognition becomes an important task performed routinely in our daily lives. This application is encouraged by the wide availability of powerful and low-cost desktop and embedded computing systems, while the need comes from the integration in too much real world systems including biometric authentication, surveillance, human-computer interaction, and multimedia management. This article proposes a new variant of LBP descriptor referred as Local Directional Multi Radius Binary Pattern (LDMRBP) as a robust and effective face descriptor. The proposed LDMRBP operator is built using new neighborhood topology and new pattern encoding scheme. The adopted face recognition system consists of th…

BED: A new dataset for EEG-based biometrics

2021

Various recent research works have focused on the use of electroencephalography (EEG) signals in the field of biometrics. However, advances in this area have somehow been limited by the absence of a common testbed that would make it possible to easily compare the performance of different proposals. In this work, we present a data set that has been specifically designed to allow researchers to attempt new biometric approaches that use EEG signals captured by using relatively inexpensive consumer-grade devices. The proposed data set has been made publicly accessible and can be downloaded from https://doi.org/10.5281/zenodo.4309471 . It contains EEG recordings and responses from 21 individuals…

Response to Discussion on Y. Zhu, X. Wang, K. Mathiak, P. Toiviainen, T. Ristaniemi, J. Xu, Y. Chang and F. Cong, Altered EEG Oscillatory Brain Netwo…

2021

The formal method in Germany and Russia : the beginnings of European psycholinguistics

2018

Abstract German–Austrian psychology is a direct source of the European formalism movement both in the German context (Germany, Austria) as well as in Russia. This interest of the formalists in the corporeal component of linguistic and literary production has resulted in a particular research stream, which could be defined as a ‘linguo-somatic orientation’. In particular, this is the case of Alois Riegl’s [1] perceptive ‘tactile–optical’ method; Adolf von Hildebrand’s [2] architectonic conception; Konrad Fiedler’s [3] ‘sensorial aesthetics’; W. Wölfflin’s [4] ‘basic concepts’ of the art history, W. Worringer’s [5] psychological arts typology as well as Oskar Walzel’s sound-corporeal poetics …

Comparison of the crystal structures of 4,4′-bis[3-(4-methylpiperidin-1-yl)prop-1-yn-1-yl]-1,1′-biphenyl and 4,4′-bis[3-(2,2,6,6-tetramethylpiperidin…

2015

The crystal structures of the two title compounds display chair conformations of the piperidine rings in their mol­ecules. In compound (I), the biphenyl system has a twisted conformation with a dihedral angle of 26.57 (6)° while in compound (II) the two phenyl rings are exactly coplanar.