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Tytuł:
Peer Review Experiences for MOOC. Development and Testing of a Peer Review System for a Massive Online Course
Autorzy:
Acosta, Enrique Sánchez
Escribano Otero, Juan José
Toletti, Gabriela Christie
Powiązania:
https://bibliotekanauki.pl/articles/2031730.pdf
Data publikacji:
2014-09-30
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
MOOC
evaluation
peer
automatism
massive
Opis:
Although at first MOOC (Massive Open Online Courses) did not use peer reviews, this kind of assessment has increasingly demonstrated the benefits that it can contribute to this type of course by improving the learning process, increasing decisions making abilities, and developing several other academic skills. Other MOOC assessment instruments do not provide students with these opportunities. This paper discusses the results obtained by the most commonly used massive online course platforms, detailing their features and limitations, as well as the experience in the implementation and use of a peer review system for a course of more than 7300 students. This study also comments on how evaluation rubrics are created, along with the final results, and the impact of the inclusion of this type of evaluation in MOOC.
Źródło:
The New Educational Review; 2014, 37; 66-79
1732-6729
Pojawia się w:
The New Educational Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Body Contouring after Massive Weight Loss – Case Report
Autorzy:
Zieliński, Tomasz
Antoszewski, Bogusław
Powiązania:
https://bibliotekanauki.pl/articles/1396893.pdf
Data publikacji:
2012-12-01
Wydawca:
Index Copernicus International
Tematy:
body contouring
plastic surgery
massive weight loss
Opis:
The paper presents a 25-year-old woman who is using a strict diet of 1000 kcal lost 83 kg in 18 months. Despite her young age, weight loss caused numerous cutaneous fatty folds, because her skin was not elastic or resilient enough. The patient undergo a multi-stage surgical treatment aiming to rectify the deformations. This example illustrates the problems of patients having undergone intensive slimming procedures and presents surgical treatment methods that rectify typical deformations in these patients.
Źródło:
Polish Journal of Surgery; 2012, 84, 11; 585-589
0032-373X
2299-2847
Pojawia się w:
Polish Journal of Surgery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The application of massing handling theory for evaluation of the application of wharves and loading facilities in the maritime port
Autorzy:
Matuszak, Z.
Bundz, S.
Jaśkiewicz, M.
Stokłosa, J.
Posuniak, P.
Powiązania:
https://bibliotekanauki.pl/articles/957983.pdf
Data publikacji:
2016
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
port system
massive handling theory
loading on ships
Opis:
This work presents the general characteristics of the port system. It defines sets and functions describing the structure and work of the port. Moreover, it characterizes foundations of the massive handling theory. It provides basic literature information about selected processes and models of the massive handling theory. On the example of a transportation company serving the loading on ships in the port of Szczecin, it shows the loading method. The material loading onto ships was the sodium water glass. There are observation results of operation times comprising the data available to determine parameters of the massive handling theory. Operations covered in the analysis include: the arrival of the ship at the port’s road, waiting for enter the port, passing through the fairway, waiting for loading, loading, determination of the cargo’s weight, preparation of documents and waiting for leaving the port. It presents critical remarks about possibilities of using the data obtained to describe loading cargo on a ship with the use of elements of the massive handling theory.
Źródło:
Advances in Science and Technology. Research Journal; 2016, 10, 31; 281-288
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved Water-Filling Power Allocation for Energy-Efficient Massive MIMO Downlink Transmissions
Autorzy:
Noor Shahida, M. K.
Nordin, R.
Insmail, M.
Powiązania:
https://bibliotekanauki.pl/articles/227000.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
energy efficiency
Massive MIMO
power allocation
spectral efficiency
Opis:
Energy Efficiency (EE) is becoming increasingly important for wireless communications and has caught more attention due to steadily rising energy costs and environmental concerns. Recently, a new network architecture known as Massive Multiple-Input Multiple-Output (MIMO) has been proposed with the remarkable potential to achieve huge gains in EE with simple linear processing. In this paper, a power allocation algorithm is proposed for EE to achieve the optimal EE in Massive MIMO. Based on the simplified expression, we develop a new algorithm to compute the optimal power allocation algorithm and it has been compared with the existing scheme from the previous literature. An improved water filling algorithm is proposed and embedded in the power allocation algorithm to maximize EE and Spectral Efficiency (SE). The numerical analysis of the simulation results indicates an improvement of 40% in EE and 50% in SE at the downlink transmission, compared to the other existing schemes. Furthermore, the results revealed that SE does not influence the EE enhancement after using the proposed algorithm as the number of Massive MIMO antenna at the Base Station (BS) increases.
Źródło:
International Journal of Electronics and Telecommunications; 2017, 63, 1; 79-84
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MOOCs, Ethics and the Economics of Higher Education
Autorzy:
McCluskey, Frank B.
Winter, Melanie
Powiązania:
https://bibliotekanauki.pl/articles/425590.pdf
Data publikacji:
2013
Wydawca:
Szkoła Główna Handlowa w Warszawie
Tematy:
MOOC
higher education
course
Massive Open Online Courses
Opis:
The starting point for article is the question: Is there something in that exchange between a single caring professor and motivated student that, while impossible to assess, measure or digitize, is at the very heart of what a university tries to be? The authors discuss the concept of Massively Open Online Classes in the context of Gartner Hype Cycle and explore MOOC ethical implications. The aim of this short article is, according to the authors, not to support or oppose the deployment of MOOCs but to clarify certain ethical presuppositions.
Źródło:
e-mentor. Czasopismo naukowe Szkoły Głównej Handlowej w Warszawie; 2013, 4 (51)
1731-6758
1731-7428
Pojawia się w:
e-mentor. Czasopismo naukowe Szkoły Głównej Handlowej w Warszawie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability and bifurcation analysis of an overhung rotor with electromagnetic actuators
Autorzy:
Przybyłowicz, Piotr M.
Kurnik, Włodzimierz
Powiązania:
https://bibliotekanauki.pl/articles/1839660.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
overhung shaft
massive disc
flutter
bifurcation
magnetic control
Opis:
A rotating system consisting of a slender massless viscoelastic shaft simply supported in rolling bearings and a rigid massive disc mounted to the overhung end of the shaft is considered to study its stabilization against flutter. Instability and transverse vibration occurs due to the internal friction in the shaft. It is shown in the paper that the disc can be stabilized and its bifurcating self-excited vibration can be effectively reduced and modified by contactless radial magnetic actuators, using two alternative control strategies – semi-active utilizing constant or rotation-dependent actuator voltage or fully active with closed-loop state-dependent feedback. The near-critical transverse disc vibration is analyzed using the theory of Hopf bifurcation. Smooth, soft-type self-excitation is presented after activation of the dynamic vibration control which prevents the system from sudden jumps of vibration amplitude near the critical point.
Źródło:
Journal of Theoretical and Applied Mechanics; 2020, 58, 2; 525-539
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A rare and overlooked cause of massive gastrointestinal bleeding: Distal duodenal GIST
Autorzy:
Düzenli, Tolga
Köseoğlu, Hüseyin
Erenler, Behice Hande
Powiązania:
https://bibliotekanauki.pl/articles/2038194.pdf
Data publikacji:
2021-06-30
Wydawca:
Uniwersytet Rzeszowski. Wydawnictwo Uniwersytetu Rzeszowskiego
Tematy:
duodenum
gastrointestinal stromal tumor
GIST
massive gastrointestinal bleeding
Opis:
Introduction. Gastrointestinal stromal tumors(GIST) are tumors of mesenchymal origin which originate from the walls of gastrointestinal system (GIS) organs. Aim. In this case report we aim to discuss the clinical, labaratory and radiological presentation of distal duodenal GIST as a rare and overlooked cause of life-threatining GIS bleeding. Description of the case. A 76-year-old male patient was presented to the emergency department with massive gastrointestinal bleeding. Computerized tomography revealed a mass soft tissue density of 4x4cm at the level of the 3-4th segment of the duodenum. At the endoscopy, there was a deep ulcer in the proximal part of the 3rd segment of the duodenum with a diameter of 2 cm with a bleeding vessel protruding into the lumen. After endoscopic treatments, biopsies were taken from the edges of the ulcer. Histopathological examination revealed a sheet-like infiltration composed of mildly pleomorphic cells with oval-spindle nuclei and abundant eosinophilic cytoplasm in the duodenal lamina propria, as the patient was diagnosed of GIST. Conclusion. GIST and its clinical, labaratory and radiological presentation should be kept in mind in the approach to massive duodenal GIS bleeding.
Źródło:
European Journal of Clinical and Experimental Medicine; 2021, 2; 189-192
2544-2406
2544-1361
Pojawia się w:
European Journal of Clinical and Experimental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemistry and tectonic setting of the volcanic host rocks of VMS mineralisation in the Qezil Dash area, NW Iran : implications for prospecting of Cyprus-type VMS deposits in the Khoy ophiolite
Autorzy:
Imamalipour, Ali
Barak, Samaneh
Powiązania:
https://bibliotekanauki.pl/articles/2058590.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
geochemistry
massive sulphide mineralisation
IAT
ophiolite
Khoy
Iran
Opis:
The uppermost part of the Khoy ophiolite includes submarine volcanic lavas. These rocks are found as two different types including basaltic pillow lavas and andesitic to andesitic basalt massive-sheet lavas known as the Qezil Dash unit. These last rocks host volcanogenic massive sulphide mineralisation (VMS). Concordant small lenticular massive sulphides associated with widespread stockworks, extensive wall rock alteration and simple mineralogical parageneses are characteristic of this mineralisation. The Qezil Dash lavas are characterized by HFSE depletion (such as in Nb, Zr, and Hf) and LILE enrichment, low Yb, Y and Ni contents and low Zr/Hf and Nb/Ta ratios. These rocks have low Ti contents and are of LKT type. These geochemical characteristics can be interpreted as indicating SSZ magmatism and suggesting that the Qezil Dash rocks belong to an early stage of island arc formation. Geochemically, this host rock is comparable with the Lasail unit, part of a volcanic sequence within the Oman ophiolite. In the Troodos and Oman ophiolites VMS mineralisation has occurred at the contacts of MOR-basalt and island arc tholeiite (IAT) lavas, so prospecting for VMS deposits in the Khoy area should be estabilished based on geochemical investigations of the volcanic rocks and recognition of their field boundaries.
Źródło:
Geological Quarterly; 2019, 63, 3; 435--448
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development and infill of Vistulian glacial Lake Gniew (N Poland) : a sedimentological analysis
Autorzy:
Błaszkiewicz, M.
Gruszka, B.
Powiązania:
https://bibliotekanauki.pl/articles/2059705.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Vistulian
glacial lake
sedimentology
glaciolacustrine deposits
massive clay
jökulhlaup
Opis:
A substantial glaciolacustrine unit in northern Poland, between the valleys of the Vistula and Wierzyca rivers, was deposited in glacial Lake Gniew during the climatic amelioration of the Late Vistulian. It covers an area of 35 km2 and has an average thickness of 7m, but locally reaches over 20 m. Four sedimentary facies are distinguished. The silty/clayey rhythmites of facies A are interpreted as varves from the central lake bottom. They represent the initial stage of lake development. Facies B is formed by a single sand layer that is interpreted as a turbidite originating during lake shallowing due to self-drainage. Facies C consists of massive clay with dropstones and dump structures. Two hypothesis regarding its genesis are put forward: the first assumes sedimentation in a shallow basin with a high input of homogenous fine-grained suspended sediment, whereas the second explains the facies as a result of amuddy jökulhlaup, pouring into Lake Gniew and being sourced from another glacial lake; further research is required to interpret this facies reliably. Facies D consists of thick silty/clayey rhythmites that are interpreted as prodeltaic deposits.
Źródło:
Geological Quarterly; 2005, 49, 4; 449--462
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Throughput, Spectral, and Energy Efficiency of 5G Massive MIMO Applications Using Different Linear Precoding Schemes
Autorzy:
Salah, Ibrahim
Rahouma, Kamel Hussein
Hussein, Aziza I.
Mabrook, M. Mourad
Powiązania:
https://bibliotekanauki.pl/articles/2203002.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
throughput
massive MIMO
spectral efficiency
energy efficiency
trade-off
Opis:
On fifth-generation wireless networks, a potential massive MIMO system is used to meet the ever-increasing request for high-traffic data rates, high-resolution streaming media, and cognitive communication. In order to boost the trade-off between energy efficiency (EE), spectral efficiency (SE), and throughput in wireless 5G networks, massive MIMO systems are essential. This paper proposes a strategy for EE 5G optimization utilizing massive MIMO technology. The massive MIMO system architecture would enhance the trade-off between throughput and EE at the optimum number of working antennas. Moreover, the EE-SE tradeoff is adjusted for downlink and uplink massive MIMO systems employing linear precoding techniques such as Multiple -Minimum Mean Square Error (M-MMSE), Regularized Zero Forcing (RZF), Zero Forcing (ZF), and Maximum Ratio (MR). Throughput is increased by adding more antennas at the optimum EE, according to the analysis of simulation findings. Next, utilizing M MMSE instead of RZF and ZF, the suggested trading strategy is enhanced and optimized. The results indicate that M-MMSE provides the best tradeoff between EE and throughput at the determined optimal ratio between active antennas and active users equipment’s (UE).
Źródło:
International Journal of Electronics and Telecommunications; 2023, 69, 1; 185--191
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Propagation and Network Analysis for a Dipole Based Massive Mimo Antenna for 5G Base Stations
Autorzy:
Pushpa, Anita Jones Mary
Chrysolite, Samuelraj
Powiązania:
https://bibliotekanauki.pl/articles/2124749.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
5G antenna
massive MIMO
dipole array
maximum gain
Opis:
In today’s fast-paced world, where everyone/everything is moving towards an online platform, the need to provide high-speed data to all is inevitable. Hence, introducing the emerging 5G technology with orthogonal frequency division multiplexing integrated with massive MIMO technology is the need of the hour. A 640 port Massive MIMO (m-MIMO) antenna with high evenly spread gain and very low delay, along with a practically possible data rate operating in the mm waveband, is proposed for a 5G base station. The individual antenna element consists of a dipole (λ=0.5cm) designed to operate at 57GHz. Placing the cylindrical MIMO antenna array (8x20) facing the four directions forming the m-MIMO antenna (160x4) at the height of 3m from ground level for simulation. Achievement of a maximum gain of 23.14dBi (θ=90▫) and a minimum data rate of 1.44Gbps with -10dB bandwidth of 2.1GHz (256-QAM) approximately a distance of 478m from the 5G Base station. The m-MIMO structure gives an Envelope Correlation Coefficient of 0.015. The propagation analysis is carried out to substantiate the performance of the proposed system based on field strength and received power. Network Analysis for better reception performance is carried out by changing the antenna height placement, altering the down tilt of the antenna array, and sweeping the polarization angle of the antenna array.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 3; 511--517
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of Hybrid Precoder for mm-Wave MIMO System Based on Generalized Triangular Decomposition Method
Autorzy:
Thurpati, Sammaiah
Muthuchidambaranathan, P.
Powiązania:
https://bibliotekanauki.pl/articles/2124753.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
millimeter-wave
mmWave
SVD
GTD
hybrid precoding
massive MIMO
Opis:
Hybrid precoding techniques are lately involved a lot of interest for millimeter-wave (mmWave) massive MIMO systems is due to the cost and power consumption advantages they provide. However, existing hybrid precoding based on the singular value decomposition (SVD) necessitates a difficult bit allocation to fit the varying signal-to-noise ratios (SNRs) of altered sub-channels. In this paper, we propose a generalized triangular decomposition (GTD)-based hybrid precoding to avoid the complicated bit allocation. The development of analog and digital precoders is the reason for the high level of design complexity in analog precoder architecture, which is based on the OMP algorithm, is very non-convex, and so has a high level of complexity. As a result, we suggest using the GTD method to construct hybrid precoding for mmWave mMIMO systems. Simulated studies as various system configurations are used to examine the proposed design. In addition, the archived findings are compared to a hybrid precoding approach in the classic OMP algorithm. The proposed Matrix Decomposition’s simulation results of signal-to-noise ratio vs spectral efficiencies.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 3; 519--525
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deep Learning-Powered Beamforming for 5G Massive MIMO Systems
Autorzy:
Bendjillali, Ridha Ilyas
Bendelhoum, Mohammed Sofiane
Tadjeddine, Ali Abderrazak
Kamline, Miloud
Powiązania:
https://bibliotekanauki.pl/articles/27312956.pdf
Data publikacji:
2023
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
5G
digital beamforming
hybrid beamforming
massive MIMO
ResNeSt
Opis:
In this study, a ResNeSt-based deep learning approach to beamforming for 5G massive multiple-input multipleoutput (MIMO) systems is presented. The ResNeSt-based deep learning method is harnessed to simplify and optimize the beamforming process, consequently improving performance and efficiency of 5G and beyond communication networks. A study of beamforming capabilities has revealed potential to maximize channel capacity while minimizing interference, thus eliminating inherent limitations of the traditional methods. The proposed model shows superior adaptability to dynamic channel conditions and outperforms traditional techniques across various interference scenarios.
Źródło:
Journal of Telecommunications and Information Technology; 2023, 4; 38--45
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient Iterative Detection Based on Conjugate Gradient and Successive Over-Relaxation Methods for Uplink Massive MIMO Systems
Autorzy:
Labed, Smail
Aounallah, Naceur
Powiązania:
https://bibliotekanauki.pl/articles/24200730.pdf
Data publikacji:
2023
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
computational complexity
conjugate gradient
massive MIMO
relaxation parameter
signal detection
Opis:
Being a crucial aspect of fifth-generation (5G) mobile communications systems, massively multiple-input multipleoutput (mMIMO) architectures are expected to help achieve the highest key performance indicators. However, the huge numbers of antennas used in such systems make it difficult to determine the inversion of the signal channel matrix relied upon by several detection methods, hence posing a problem with accurate estimation of the symbols sent. In this paper, conjugate gradient (CG) and successive over-relaxation (SOR) methods are selected to construct a new iterative approach that avoids the matrix inversion computation issue. This suggested approach for uplink mMIMO detection is based on a joint cascade structure of both iterative methods. The CG method is first applied and adjusted for the initial solution, followed by the SOR method in the final iterations for terminal computations, resulting in an algorithm with robust performance and low computational complexity. Furthermore, the new hybrid scheme operates based on the relaxation parameter, whose value has a great impact on error performance and, whose optimal determination is necessary. Numerical simulations reveal that the proposed scheme is capable of significantly improving signal detection accuracy with minimum complexity. The simulation results indicated that the proposed detector outperforms CG and SOR detectors, achieves close to optimal performance, requires fewer iterations, and reduces complexity.
Źródło:
Journal of Telecommunications and Information Technology; 2023, 2; 1--9
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Successful MOOC project “IT School” for informatics education on secondary level
Autorzy:
Galwas, B.
Żyławski, A.
Powiązania:
https://bibliotekanauki.pl/articles/91337.pdf
Data publikacji:
2013
Wydawca:
Warszawska Wyższa Szkoła Informatyki
Tematy:
innovation
research projects
IT education
Massive Open Online Courses
MOOC
Opis:
Warsaw School of Computer Science has launched a multi-annual MOOC project “IT School” to prepare and open on-line a number of popular courses and other materials in the area of “basics of computer knowledge” for students of secondary level. The main objective of the project “IT School” is to popularize basic knowledge of computer technology, to encourage young people to study in the field of Information Technology and thus facilitate the study of the core courses. In the framework of Project twelve online courses was prepared and opened with particular care in preparing self-assessment tests, allowing students to check the level of understanding of the learning material after each course (http://www.it-szkola.edu.pl). The final test assesses student knowledge and its completion allows to receive a certificate. The education technology used for preparing the lectures is explained in this paper in details.
Źródło:
Zeszyty Naukowe Warszawskiej Wyższej Szkoły Informatyki; 2013, 7, 10; 39-52
1896-396X
2082-8349
Pojawia się w:
Zeszyty Naukowe Warszawskiej Wyższej Szkoły Informatyki
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of injection method to modify titanium alloy Ti6Al4V
Autorzy:
Klimas, J.
Łukaszewicz, A.
Szota, M.
Nabiałek, M.
Powiązania:
https://bibliotekanauki.pl/articles/285312.pdf
Data publikacji:
2014
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
biomaterials
titanium alloy Ti-6Al-4V
massive amorphous alloy
Opis:
In the present work, the samples were subjected to a comparative analysis of the titanium alloy Ti6Al4V prepared by various methods. The research included a comparison of the following properties of manufactured elements: microstructure, phase composition and surface roughness. The test results clearly showed that these properties are different when using different method of casting. These changes allows the use of prepared elements in medicine.
Źródło:
Engineering of Biomaterials; 2014, 17, no. 128-129; 91-92
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Analysis of Procedures and Solutions to Improve Energy Efficiency of Massive MIMO
Autorzy:
Phogat, Ritu Singh
Joshi, Rutvij
Powiązania:
https://bibliotekanauki.pl/articles/2200684.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
EE
Uplink-Downlink Transmission
power control
linear precoding
CF Massive MIMO
Opis:
The blustery growth of high data rate applications leads to more energy consumption in wireless networks to satisfy service quality. Therefore, energy-efficient communications have been paid more attention to limited energy resources and environmentally friendly transmission functioning. Countless publications are present in this domain which focuses on intensifying network energy efficiency for uplink-downlink transmission. It is done either by using linear precoding schemes, by amending the number of antennas per BS, by power control problem formulation, antenna selection schemes, level of hardware impairments, and by considering cell-free (CF) Massive-MIMO. After reviewing these techniques, still there are many barriers to implement them practically. The strategies mentioned in this review show the performance of EE under the schemes as raised above. The chief contribution of this work is the comparative study of how Massive MIMO EE performs under the background of different methods and architectures and the solutions to few problem formulations that affect the EE of network systems. This study will help choose the best criteria to improve EE of Massive MIMO while formulating a newer edition of testing standards. This survey provides the base for interested readers in energy efficient Massive MIMO.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 4; 677--686
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Main Challenges in Higher Education on the Case Study of Selected xMOOCs Providers: Coursera, and edX
Autorzy:
Durasiewicz, Arkadiusz
Duranowski, Wojciech
Barszczewski, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/2036198.pdf
Data publikacji:
2015-12-31
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
massive open online course
MOOC
xMOOCs
elearning
free online courses
mobile learning
Opis:
MOOC is one of the forthcoming challenges of global higher education system. Development of education system cannot be considered without global trends. Massive Open Online Courses (MOOCs) become more and more popular. Article focuses on analysis of case studies of the most important xMOOCs providers: Coursera, edX. Authors focuses their analysis on direction of the development of xMOOCs in higher education as well as on key barriers for further development of the model.
Źródło:
Kultura i Edukacja; 2015, 4 (110); 182-200
1230-266X
Pojawia się w:
Kultura i Edukacja
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oddziaływania allelopatyczne sinic i mikroglonów w środowisku wodnym
Allelopathic interactions of cyanobacteria and microalgae in aquatic ecosystem
Autorzy:
Śliwińska-Wilczewska, Sylwia
Latała, Adam
Powiązania:
https://bibliotekanauki.pl/articles/1034158.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Przyrodników im. Kopernika
Tematy:
allelopathy
aquatic environment cyanobacteria
massive blooms microalgae
allelopatia
mikroglony
sinice
środowisko wodne
Opis:
Termin "allelopatia" został wprowadzony do nauki w 1937 r. przez austriackiego profesora Hansa Molischa. Użył on pojęcia allelopatii do określenia wzajemnego oddziaływania pomiędzy organizmami roślinnymi poprzez wydzielanie związków chemicznych. W 1996 r. International Allelopathy Society poszerzyło tę definicję, wskazując, że jest to każdy proces, w którym substancje chemiczne wydzielane przez jedne organizmy oddziałują na rozwój innych gatunków roślinnych i zwierzęcych. Oddziaływanie allelopatyczne może być istotnym czynnikiem wpływającym na formowanie się masowych zakwitów sinic i mikroglonów w wielu zbiornikach wodnych. Zakwity tych organizmów w ostatnich dziesięcioleciach znacznie się nasiliły i stanowią dziś poważny problem ekologiczny i ekonomiczny. Dostarczenie nowych informacji na temat sposobu i zakresu oddziaływania allelopatycznego sinic i mikroglonów może mieć ważne znaczenie dla pełniejszego zrozumienia nasilającego się na całym świecie zjawiska masowych zakwitów tych organizmów w wielu ekosystemach wodnych
The term "allelopathy" was introduced to science in 1937 by Hans Molisch, who used the concept of allelopathy to identify negative impact of chemicals secreted by a plant on the growth of other neighboring plants. In 1996, the International Allelopathy Society has broadened the meaning of allelopathy as any inhibitory or stimulatory process in which chemical substances secreted by various organisms interact with their ecosystem. Allelopathy may be one of the factors contributing to formation and maintenance of cyanobacterial and algal blooms, which strongly affect coastal marine ecosystems and cause economic problems for commercial aquaculture. A better understanding of the complexity and nature of underlying allelopatic interactions may help to explain the emergence of massive blooms of cyanobacteria and algae in many aquatic ecosystems.
Źródło:
Kosmos; 2017, 66, 2; 217-224
0023-4249
Pojawia się w:
Kosmos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-shifted Pilot-based Scheduling with Adaptive Optimization for Pilot Contamination Reduction in Massive MIMO
Autorzy:
Kumar, Ambala Pradeep
Srinivasulu, Tadisetty
Powiązania:
https://bibliotekanauki.pl/articles/1839309.pdf
Data publikacji:
2020
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
massive MIMO
pilot contamination
sparse FCM
time-shifted pilot scheduling
user grouping
Opis:
Massive multiple-input multiple-output (MIMO) is considered to be an emerging technique in wireless communication systems, as it offers the ability to boost channel capacity and spectral efficiency. However, a massive MIMO system requires huge base station (BS) antennas to handle users and suffers from inter-cell interference that leads to pilot contamination. To cope with this, time-shifted pilots are devised for avoiding interference between cells, by rearranging the order of transmitting pilots in different cells. In this paper, an adaptive-elephant-based spider monkey optimization (adaptive ESMO) mechanism is employed for time-shifted optimal pilot scheduling in a massive MIMO system. Here, user grouping is performed with the sparse fuzzy c-means (Sparse FCM) algorithm, grouping users based on such parameters as large-scale fading factor, SINR, and user distance. Here, the user grouping approach prevents inappropriate grouping of users, thus enabling effective grouping, even under the worst conditions in which the channel operates. Finally, optimal time-shifted scheduling of the pilot is performed using the proposed adaptive ESMO concept designed by incorporating adaptive tuning parameters. The efficiency of the adaptive ESMO approach is evaluated and reveals superior performance with the highest achievable uplink rate of 43.084 bps/Hz, the highest SINR of 132.9 dB, and maximum throughput of 2.633 Mbps.
Źródło:
Journal of Telecommunications and Information Technology; 2020, 4; 10-21
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
AMP: A tool for characterizing the pedagogical approaches of MOOCs
Autorzy:
Swan, Karen
Day, Scott
Bogle, Leonard
van Prooyen, Traci
Powiązania:
https://bibliotekanauki.pl/articles/426399.pdf
Data publikacji:
2014
Wydawca:
Szkoła Główna Handlowa w Warszawie
Tematy:
AMP
Assessing MOOC Pedagogies
MOOCs
Massive Open Online Courses
pedagogy
e-learning
Opis:
This article reports on the development and validation of a tool for characterizing the pedagogical approaches taken in MOOCs (Massive Open Online Courses). The Assessing MOOC Pedagogies (AMP) tool characterizes MOOC pedagogical approaches on ten dimensions. Preliminary testing on 17 different MOOCs demonstrated >80% inter-reliability and the facility of the measure to distinguish differing pedagogical patterns. The patterns distinguished crossed content areas and seemed to be related to what Sfard1 termed metaphors for learning - acquisition vs. participation.
Źródło:
e-mentor. Czasopismo naukowe Szkoły Głównej Handlowej w Warszawie; 2014, 2 (54); 75-85
1731-6758
1731-7428
Pojawia się w:
e-mentor. Czasopismo naukowe Szkoły Głównej Handlowej w Warszawie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power Scaling and Antenna Selection Techniques for Hybrid Beamforming in mmWave Massive MIMO Systems
Autorzy:
Nalband, Abdul Haq
Sarvagya, Mrinal
Ahmed, Mohammed Riyaz
Powiązania:
https://bibliotekanauki.pl/articles/226190.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
antenna selection
massive MIMO
millimeter Wave
5G
hybrid beamforming
power scaling
Opis:
With the advent of massive MIMO and mmWave, Antenna selection is the new frontier in hybrid beamforming employed in 5G base stations. Tele-operators are reworking on the components while upgrading to 5G where the antenna is a last-mile device. The burden on the physical layer not only demands smart and adaptive antennas but also an intelligent antenna selection mechanism to reduce power consumption and improve system capacity while degrading the hardware cost and complexity. This work focuses on reducing the power consumption and finding the optimal number of RF chains for a given millimeter wave massive MIMO system. At first, we investigate the power scaling method for both perfect Channel State Information (CSI) and imperfect CSI where the power is reduced by1/Nᵣ and 1/√Nᵣ respectively. We further propose to reduce the power consumption by emphasizing on the subdued resolution of Analog-to-Digital Converters (ADCs) with quantization awareness. The proposed algorithm selects the optimal number of antenna elements based on the resolution of ADCs without compromising on the quality of reception. The performance of the proposed algorithm shows significant improvement when compared with conventional and random antenna selection methods.
Źródło:
International Journal of Electronics and Telecommunications; 2020, 66, 3; 529-535
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The evolution of arc magmatism related to Palaeotethys in the west of Salmas, north of the Sanandaj-Sirjan Zone, Iran
Autorzy:
Fazlnia, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060346.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
layered gabbros
massive gabbrodiorite
appinite
geochemical-mineralogical modelling
tectono-magmatic model
Zagros
Opis:
The Mingol-Mamakan gabbroic-appinitic intrusions are located in northwestern part of Iran and belong to the Sanandaj–Sirjan zone (SSZ). These intrusions have had a significant impact on evolution of the northwestern part of the SSZ during Upper Carboniferous. The rocks typically include layered and massive gabbros-gabbrodiorites. The age of layered gabbros is 303-300 Ma and they mainly consist of leuco-gabbro, mezzo-gabbro, melano-gabbro, anorthosite, and hornblendite (appinite) with gradational or sharp bedding contacts alternatively. Layered gabbros with 314-322 Ma are mostly composed of leuco-gabbro, mezzo-gabbro, melano-gabbro, and hornblendite. Most of these samples are appinite in composition. The intrusions show no obvious deformation. Therefore, mineral composition changes in the rocks have been controlled by crystallization processes, such as fractionation in the magma chamber. Our investigations indicate that different rock types with tholeiitic magma series are probably derived from partial melting of spinel lherzolite upper mantle co-genetic source. Geochemical information and dating from the Mingol-Mamakan intrusive rocks reveal that the intrusions were formed of subduction-related immature or sub-mature island arc tholeiitic basalt which is enriched in Al2O3, FeO, Sr and depleted in K and Nb. Subsequently, primary tholeiitic arc basalt magma underwent fractional crystallization to form intrusive rocks at the lower crust, relatively in high pressures conditions. Geochemical modeling based on the partition coefficient of elements in minerals indicates that trace elements concentrations (large-ion lithophile elements, LILEs, high field strength elements, HFSE, and rare earth elements, REEs) in the Mingol-Mamakan intrusions throughout the crystallization were controlled by variable amounts of common minerals such as amphibole, clinopyroxene (for all trace elements) plagioclase (only for LILE) and probably spinel in the source rock (only for HFSE). Moreover, elements of first transition series of periodic table mainly controlled by orthopyroxene, olivine and possibly by clinopyroxene and amphibole in much smaller amounts.
Źródło:
Geological Quarterly; 2017, 61, 1; 124--137
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Method of Inoculation of High-Quality Grey Cast Iron Intended for Massive Castings for Bottom and Distance Plates as Well Counterweights Manufactured as Vertical Castings
Autorzy:
Guzik, Edward
Kopyciński, Dariusz
Ziółko, A.
Szczęsny, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/2203754.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high-quality cast iron
heavy castings
massive casting
graphitizing inoculation
hybrid inoculation
Opis:
The technology of producing castings of high-quality inoculated cast iron with flake graphite particles in the structure is a combination of the melting and inoculation process. Maintaining the stability of the strength and microstructure parameters of this cast iron is the goal of a series of studies on the control of graphitization and austenitic inoculation (increasing the number of primary austenite dendrites), and which affects the type of metal matrix in the structure. The ability to graphitize the molten alloy decreases with its holding in the melting furnace more than an hour. The tendency to crystallize large dendritic austenite grains and segregation of elements such as Si, Ni and Cu reduce the ductility properties of this cast iron. The austenite inoculation process may introduce a larger number of primary austenite grains into the structure, affecting the even distribution of graphite and metal matrix precipitation in the structure. Known inoculation effects the interaction (in low mass) of additives: Sr, Ca, Ba, Ce, La, produces MC2 carbide). Addition of Fe in the inoculant influences the number and shape of austenite dendrites. Hybrid modification combines the effects of these two factors. The introduction of nucleation sites for the graphite eutectics and primary austenite grains result in the stabilization of the cast iron microstructure and an increase in mechanical properties. The obtained test results set the direction for further research in this area in relation to the production of heavy plate castings in vertical and horizontal pouring.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 359--368
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sea-floor massive sulphides from the Galápagos Rift Zone – mineralogy, geochemistry and economic importance
Autorzy:
Szamałek, K.
Marcinowska, A.
Nejbert, K.
Speczik, S.
Powiązania:
https://bibliotekanauki.pl/articles/2059147.pdf
Data publikacji:
2011
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Galápagos Rift Zone
sea-floor massive sulphides (SMS)
mineralogy and geochemistry
economic evaluation
Opis:
The largest reserves of the Earth's mineral resources are located on the ocean floor. Amongst these, hydrocarbon and metallic resources are of the greatest importance. In 2010, the International Seabed Authority (ISA) adopted rules for documenting new metal resources contained with polymetallic sea-floor massive sulphides (SMS). Russia and China were the first countries to apply to the ISA to acquire the right to commence initial investigation and documentation in the Indian and Atlantic oceans. Apart from copper, cobalt and nickel, modern SMS ores contain inferred significant amounts of gold, silver and PGE. The results described here from Galápagos Rift samples indicate a high concentration of gold (up to 7.24 ppm) and platinum (up to 350 ppb), which are mainly concentrated in low temperature parts of the sulphide mounds. The high content of Au and Pt revealed by this study provides further motivation towards attempting the exploration of marine massive sulphides. This is particularly important in the light of the high prices of metal commodities, and especially the unprecedented price of gold. This paper is the first such detailed scientific account in the Polish scientific literature focusing on the genesis and economic significance of the modern sea-floor sulphides.
Źródło:
Geological Quarterly; 2011, 55, 3; 187-202
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
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