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Abstract

This paper presents the results of an experimental study and
mathematical modeling of the effect of dynamic instabilities on the condensation phase transformation of the refrigerants homogeneous R134a and its replacement in the form of isomers R1234yf and R1234ze and R404A or R507 and R448A in pipe mini-channels. In the case of homogeneous chlorofluorocarbons (CFCs), it is the 1234 isomers that are envisioned as substitutes for the withdrawn ones with high ozone depletion potential and global warming potential. For zeotropic and azeotropic mixtures, for example, these are R507 or R448A. The paper presents a dimensional analysis procedure based on the Buckingham Π theorem to develop a regression velocity model of pressure dynamic instabilities. The experimental part of the work was carried out with the use of tubular mini-channels with internal diameter 1.40–3.3 mm.
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Authors and Affiliations

Waldemar Kuczyński
1

  1. Koszalin University of Technology, Faculty of Mechanical Engineering, Department of Power Engineering, Racławicka 15-17, 75-625 Koszalin, Poland
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Abstract

The results of the first (since 1939) hydrochemical investigations of Gliwice Channel have been presented. The polluted K.lodnica River affects bad water quality of the canal. For example the concentrations of chlorides (Cl), sulfates (S04), sodium (Na), potassium (K), conductivity and dissolved substances quality of water is out of standards. In the case of BOD and COD the water quality is changed from out of classes to II class. pH and oxygen concentration are in I class. Although no salinity waters flow into the canal, the water quality get improved slightly only. The decrease of pollutants concentration is related to theirs dispersion. In the case of water quality the self-purification processes are of secondary importance.
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Authors and Affiliations

Maciej Kostecki
Jerzy Kozłowski
Bartłomiej Zych
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Abstract

Due to the multifold growth in demands of multimedia services and mobile data, the request for increased channel capacity in mobile and wireless communication has been quickly increasing. Developing a wireless system with more spectral efficiency under varying channel condition is a key challenge to provide more bit rates with limited spectrum. Multiple Input Multiple Output (MIMO) system with Orthogonal Frequency Division Multiplexing (OFDM) gives higher gain by using the direct and the reflected signals, thus facilitating the transmission at high data rate. An integration of Spatial Modulation (SM) with OFDM (SM OFDM) is a newly evolved transmission technique and has been suggested as a replacement for MIMO -OFDM transmission. In practical scenarios, channel estimation is significant for detecting transmitted data coherently. This paper proposes pilot based, Minimum Mean Square Error (MMSE) channel estimation for the SM OFDM communication system. We have focused on analyzing Symbol Error Rate (SER) and Mean Square error (MSE) under Rayleigh channel employing International Telecommunication Union (ITU) specified Vehicular model of Pilot based MMSE channel estimator using windowed Discrete Fourier Transform (DFT) and MMSE weighting function. Simulation output shows that proposed estimator’s SER performance lies close to that of the MMSE optimal estimator in minimizing aliasing error and suppressing channel noise by using frequency domain data windowing and time domain weighting function. Usage of the Hanning window eliminates error floor and has a compact side lobe level compared to Hamming window and Rectangular window. Hanning window has a larger MSE at low Signal to Noise Ratio (SNR) values and decreases with high SNR values. It is concluded that data windowing technique can minimize the side lobe level and accordingly minimize channel estimation error when interpolation is done. MMSE weighting suppresses channel noise and improves estimation performance. Since Inverse Discrete Fourier Transform (IDFT)/DFT transforms can be implemented with fast algorithms Inverse Fast Fourier Transform( IFFT)/Fast Fourier Transform (FFT) computational complexity can be remarkably reduced.
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Bibliography

[1] A. Mohammadi, F.M. Ghannouchi, “Single RF front-end MIMO transceivers,” in RF transceiver design for MIMO wireless communications, Springer, Berlin, Heidelberg, pp. 265-288, 2012.
[2] R. Mesleh, H. Haas, C.W. Ahn, S. Yun, “Spatial modulation-a new low complexity spectral efficiency enhancing technique,” in 2006 First International Conference on Communications and Networking in China IEEE, pp. 1-5, Oct 25, 2006.
[3] M. Wen, B. Zheng, K.J. Kim, M. Di Renzo, T.A. Tsiftsis, K.C. Chen, N. Al-Dhahir, “A survey on spatial modulation in emerging wireless systems: Research progresses and applications,” IEEE Journal on Selected Areas in Communications, 37(9): 1949-72, Jul 17, 2019.
[4] H. Doğan, E. Panayırcı, H.V. Poor, “Low-complexity joint data detection and channel equalisation for highly mobile orthogonal frequency division multiplexing systems,” IET communications, 4(8): 1000-11, May 21, 2010.
[5] H. Haas, S. Sinanovic, C.W. Ahn, S. Yun, “Spatial modulation,” IEEE Trans. Veh. Technol, 57(4): 2228-41, Jul 2008.
[6] M. Biguesh, A.B. Gershman, “Training-based MIMO channel estimation: a study of estimator tradeoffs and optimal training signals,” IEEE transactions on signal processing, 54(3):884-93, Feb 21, 2006.
[7] M. Yalcin, A. Akan, H. Doğan, “Low-complexity channel estimation for OFDM systems in high-mobility fading channels,” Turkish Journal of Electrical Engineering & Computer Sciences, 25;20(4): 583-92, Apr. 2012.
[8] J.G. Andrews, A. Ghosh and R. Muhamed, “Fundamentals of WiMAX: understanding broadband wireless networking,” Pearson Education; Feb 27, 2007.
[9] E. Dahlman, S. Parkvall, J. Skold, “4G: LTE/LTE- advanced for mobile broadband,” Academic Press, Oct 7, 2013.
[10] S. Coleri, M. Ergen, A. Puri, A. Bahai, “Channel estimation techniques based on pilot arrangement in OFDM systems,” IEEE Transactions on broadcasting, 7;48(3): 223-9, Nov 2002 .
[11] Y. Wu, Y. Zhao, D. Li, “Channel estimation for pilot-aided OFDM systems in single frequency network,” Wireless Personal Communications, 1;62(1): 227-45, Jan 2012.
[12] H. Doğan, “On detection in MIMO-OFDM systems over highly mobile wireless channels,” Wireless personal communications, 86(2): 683-704, Jan 2016.
[13] Y. Acar, H. Doğan, E. Panayirci, “Pilot symbol aided channel estimation for spatial modulation-OFDM systems and its performance analysis with different types of interpolations,” Wireless Personal Communications, 94(3): 1387-404, Jun 2017.
[14] M. Speth, S. Fechtel, G. Fock, H. Meyr, “Broadband transmission using OFDM: System performance and receiver complexity,” in 1998 International Zurich Seminar on Broadband Communications. Accessing, Transmission, Networking. Proceedings (Cat. No. 98TH8277), IEEE, pp. 99-104, Feb 1998.
[15] F. Ling, C.L. Nikias, J.G. Proakis, C.M. Rader, “Advanced digital signal processing,” Macmillan, 1992.
[16] B. Yang, Z. Cao, K.B. Letaief, „Analysis of low-complexity windowed DFT-based MMSE channel estimator for OFDM systems,” IEEE Transactions on Communications, 49(11): 1977-87, Nov 2001.
[17] Y. Li, “Pilot-symbol-aided channel estimation for OFDM in wireless systems,” IEEE transactions on vehicular technology, 49(4):1207-15, Jul 2000.
[18] P. Hoeher, S. Kaiser, P. Robertson, “Two-dimensional pilot symbol-aided channel estimation by Wiener filtering,” in 1997 IEEE international conference on acoustics, speech, and signal processing, IEEE, Vol. 3, pp. 1845-1848, Apr 1997.
[19] Y. L. Li, L.J. Cimini, N. R. Sollenberger, “Robust channel estimation for OFDM systems with rapid dispersive fading channels,” IEEE Transactions on communications, 46(7): 902-15, Jul 1998.
[20] O. Edfors, M. Sandell, J.J. Van De Beek, S.K. Wilson, P.O. Börjesson, “Analysis of DFT-based channel estimators for OFDM,” Wireless Personal Communications, 1;12(1): 55-70, Jan 2000.
[21] V.K. Jones, G.C. Raleigh, “Channel estimation for wireless OFDM systems,” in IEEE GLOBECOM 1998 (Cat. NO. 98CH36250), IEEE, Vol. 2, pp. 980-985, Nov 8, 1998.
[22] Y. Zhao, A. Huang, “A novel channel estimation method for OFDM mobile communication systems based on pilot signals and transform-domain processing,” in 1997 IEEE 47th Vehicular Technology Conference. Technology in Motion, IEEE, Vol. 3, pp. 2089-2093, May 1997.
[23] B. Yang, K.B. Letaief, R.S. Cheng, Z. Cao, “Windowed DFT based pilot-symbol-aided channel estimation for OFDM systems in multipath fading channels,” in VTC2000-Spring, 2000 IEEE 51st Vehicular Technology, 2020 Conference Proceedings (Cat. No. 00CH37026), IEEE, Vol. 2, pp. 1480-1484, May 15 ,2000.
[24] J.J. Van De Beek, O. Edfors, M. Sandell, S.K. Wilson, P.O. Borjesson “On channel estimation in OFDM systems,” in 1995 IEEE 45th Vehicular Technology Conference. Countdown to the Wireless Twenty-First Century, IEEE, Vol. 2, pp. 815-819, Jul 25 ,1995.
[25] ITU-R M.1225(1997) International Telecommunication Union, “Guidelines for evaluation of radio transmission technologies for IMT-2000,” 1997.
[26] M. Patzold, “Mobile fading channels,” Hoboken: Wiley, 2003
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Authors and Affiliations

Anetha Mary Soman
1
R. Nakkeeran
1
Mathew John Shinu
2

  1. Department of Electronics Engineering, School of Engineering and Technology, Pondicherry Central University, Pondicherry, India
  2. Department of Computer Science, St.ThomasCollege of Engineering & Technology, Kannur, Kerala, India
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Abstract

The current paper is a review of the results attained in the past and current anatomical studies, aimed at understanding the variability and function of the diploic venous system of the human skull. The diploic veins can serve as transit for infections from the scalp to the structures contained within the cranial cavity via the emissary veins, due to their interconnections with the pericranial veins, meningeal veins and dural sinuses. Thereby this clinical aspect has also been discussed.
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Authors and Affiliations

Janusz Skrzat
1
Michał Zarzecki
1

  1. Department of Anatomy, Jagiellonian University Medical College, Kraków, Poland
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Abstract

Results of the study presented in this article and earlier have been the first ones since the Gliwice Canal was put into service in 1939. Until now there have been no investigations concernig (the Canal state in the area of hydro-chemical study), sanitary state or level of sediment contamination. The aim of this study was therefore to obtain information about the current pollution. The level of aquatic environment in some reaches of Gliwice Channel. This article presents the results of investigations carried out in order to assess of water quality in the Canal relating to nitrogen and phosphorus compounds. The following nutrients were determined in water samples ammonia, nitrite and nitrate nitrogen as well as organic dissolved and organic suspended nitrogen. In addition concentrations of orthophosphates, polyphosphates and organic phosphorus were analyzed. The analyses were carried out in water samples taken in six samplings from January till June 2000. Water samples were drawn at 7 sampling points. Samples of bottom sediments were taken at 21 sample points. Basing on the results of analyses the water quality of Gliwice Canal has been determined. A classification of chemical parameters was carried out under the provision in force. Basing on this classification we can state that water in the Canal is does not quality for any class system. We can also affirm that the water quality on the whole length of Gliwice Canal has improved only slightly even though waters of lower pollution levels supply the Canal.
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Authors and Affiliations

Maciej Kostecki
Jerzy Kozlowski
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Abstract

MIMO technology has become very popular in a wireless communication system because of the many advantages of multiple antennas at the transmitting end and receiving end. The main advantages of MIMO systems are higher data rate and higher reliability without the need of extra power and bandwidth. The MIMO system provides higher data rate by using spatial multiplexing technique and higher reliability by using diversity technique. The MIMO systems have not only advantages, but also have disadvantages. The main disadvantage of MIMO system is that the multiple antennas required extra high cost RF modules. The extra RF modules increase the cost of wireless communication systems. In this research, the antenna selection techniques are proposed to minimize the cost of MIMO systems. Furthermore, this research also presents techniques for antenna selection to enhance the capacity of channel in MIMO systems.

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Authors and Affiliations

Dalveer Kaur
Neeraj Kumar
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Abstract

In a parallel time-interleaved data sampling system, timing and amplitude mismatches of this structure degrade the performance of the whole ADC system. In this paper, an adaptive blind synthesis calibration algorithm is proposed, which could estimate the timing, gain and offset errors simultaneously, and calibrate automatically. With no need of an extra calibration signal and redesign, it could efficiently and dynamically track the changes of mismatches due to aging or temperature variation. A fractional delay filter is developed to adjust the timing mismatch, which simplifies the design and decreases the cost. Computer simulations are also included to demonstrate the effectiveness of the proposed method.

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Authors and Affiliations

Huiqing Pan
Shulin Tian
Peng Ye
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Abstract

One of the crucial advancements in next-generation 5G wireless networks is the use of high-frequency signals specifically those are in the millimeter wave (mm-wave) bands. Using mmwave frequency will allow more bandwidth resulting higher user data rates in comparison to the currently available network. However, several challenges are emerging (such as fading, scattering, propagation loss etc.), whenever we utilize mm-wave frequency wave bands for signal propagation. Optimizing propagation parameters of the mm-wave channels system are much essential for implementing in the real-world scenario. To keep this in mind, this paper presents the potential abilities of high frequencies signals by characterizing the indoor small cell propagation channel for 28, 38, 60 and 73 GHz frequency band, which is considered as the ultimate frequency choice for many of the researchers. The most potential Close-In (CI) propagation model for mm-wave frequencies is used as a Large-scale path loss model. Results and outcomes directly affecting the user experience based on fairness index, average cell throughput, spectral efficiency, cell-edge user’s throughput and average user throughput. The statistical results proved that these mm-wave spectrum gives a sufficiently greater overall performance and are available for use in the next generation 5G mobile communication network.

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Authors and Affiliations

Faizan Qamar
MHD Nour Hindia
Talib Abbas
Kaharudin Bin Dimyati
Iraj S. Amiri
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Abstract

Multiple input multiple output (MIMO) is a multiple antenna technology used extensively in wireless communication systems. With the ever increasing demand in high data rates, MIMO system is the necessity of wireless communication. In MIMO wireless communication system, where the multiple antennas are placed on base station and mobile station, the major problem is the constant power of base station, which has to be allocated to data streams optimally. This problem is referred as a power allocation problem. In this research, singular value decomposition (SVD) is used to decouple the MIMO system in the presence of channel state information (CSI) at the base station and forms parallel channels between base station and mobile station. This practice parallel channel ensures the simultaneous transmission of parallel data streams between base station and mobile station. Along with this, water filling algorithm is used in this research to allocate power to each data stream optimally. Further the relationship between the channel capacity of MIMO wireless system and the number of antennas at the base station and the mobile station is derived mathematically. The performance comparison of channel capacity for MIMO systems, both in the presence and absence of CSI is done. Finally, the effect of channel correlation because of antennas at the base stations and the mobile stations in the MIMO systems is also measured.

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Authors and Affiliations

Dalveer Kaur
Neeraj Kumar
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Abstract

In this paper, we estimate the upper limit of the transmission data rate in airborne ultrasonic communications, under condition of the optimal power allocation. The presented method is based on frequency response of a channel in case of single-path LOS propagation under different climatic conditions and AWGN background noise model, and it can be easily extended to the case of frequency-dependent noise. The obtained results go beyond the discrete distances for which experimental SNR values were available, and are more accurate than the previous calculations in the literature, due to the inclusion of the channel frequency response and its changes over the distance. The impact of air temperature, relative humidity and the atmospheric pressure on the channel capacity is also investigated. The presented results can serve as a reference during the design of airborne ultrasonic communication systems operating in the far-field region.

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Authors and Affiliations

Gustaw Mazurek
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Abstract

The article is the result of a project aimed at developing and implementing a design of composite accessories for support in excavations located in underground hard coal mines. The research team verified the possibility of using elements made of prefabricated composite structural profile as an alternative to steel and reinforced concrete lining elements used to improve support’s stability and protect against rockfall.
This paper includes a research experiment on the possibilities of using a composite C-profile element as lining made in the pultrusion technology with a longitudinal position of the roving. The prefabricated structural profiles were adapted to the function by designing seatings for fitting the flanges for arch support’s V-profiles. Prototypes of these elements were subjected to bench tests in compliance with the guidelines for testing mesh linings. In addition, computer simulations using the finite element method were carried out.
The values obtained during the tests were compared with the requirements for lightweight mesh and included the Polish standard PN-G-15050 and reinforced A-type concrete lining defined in the standard ­PN-G-06021. The team determined the areas where material strength exceeded and the structure was damaged. Despite the limited quantity of laboratory tests and lack of field tests in actual mining conditions, it was possible to address the argument of the research and determine whether it is possible to use C-profile made in the pultrusion technology as a lining element.
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Bibliography

[1] PN-G-15050:2018-01 Obudowa wyrobisk górniczych. Siatki okładzinowe zgrzewane.
[2] PN-G-06021:1997 Obudowa górniczych wyrobisk korytarzowych. Okładziny żelbetowe.
[3] M. Rotkegel. Wpływ sposobu montażu siatek okładzinowych na ich pracę. Przegląd Górniczy 70 (3), 79-85 (2014).
[4] J. Olszewski, Leksykon górniczy: praca zbiorowa. Katowice: Wydawnictwo Śląsk (1989).
[5] L . Nickels, The future of pultrusion. Reinf. Plast. 63 (3), 132-135 (2019). DOI: https://doi.org/10.1016/j.repl.2019.01.003
[6] G .G. Litwinskij, G.I. Gajko, N.I. Kyldyrkajew, Stalnyje ramnyje kriepi gornych wyrabotok. Kijew: Technika (1999).
[7] M. Grodzicki, M. Rotkegel, The concept of modification and analysis of the strength of steel roadway supports for coal mines in the Soma Basin in Turkey. Studia Geotechnica et Mechanica 40 (1), 38-45 (2018). DOI: https://doi.org/10.2478/sgem-2018-0006
[8] G .I. Gayko, M. Rotkegel, Issliedowanija niesuszcziej sposobnosti arocznoj kriepi pri razlicznych wariantach nagrużienia. Ugoł Ukrainy 2, 45-47 (2003).
[9] P. Horyl, R. Snuparek, P. Marsalek, K. Pacześniowski, Simulation of laboratory tests of steel arch support. Arch. Min. Sci. 62 (1), 63-176 (2017). DOI: http://doi.org/10.1515/amsc-2017-0012455
[10] H. Filcek, J. Walaszczyk, A. Tajduś, 1994. Metody komputerowe w geomechanice górniczej. Śląskie Wydawnictwo Techniczne (1994).
[11] R .D. Cook, D.S. Malkus, M.E. Plesha, R.J. Witt, Finite Element Modeling for Stress Analysis. John Wiley & Sons, Inc. (2002).
[12] CO SMOS/M User’s Guide, Los Angeles, Structural Research & Analysis Corp. (1999).
[13] E. Rusiński, Metoda elementów skończonych. System COSMOS/M. Wydawnictwo Komunikacji i Łączności (1994).
[14] A. Pytlik. Tests of steel arch and rock bolt support resistance to static and dynamic loading induced by suspended monorail transportation. Studia Geotechnica et Mechanica 41 (2), 81-92 (2019). DOI: https://doi.org/10.2478/sgem-2019-0009
[15] A. Pytlik. Comparative bench testing of steel arch support systems with and without rock bolt reinforcements. Arch. Min. Sci. 64 (4), 747-764 (2019). DOI: http://doi.org/10.24425/ams.2019.131064
[16] PN-G-15022:2018-11 Odrzwia podatne z kształtowników korytkowych – Wymagania wytrzymałościowe i badania.
[17] PN-G-15024:2017-10 Obudowa wyrobisk górniczych – Rozpory stalowe dwustronnego działania.
[18] PN-G-15026:2017-04 Obudowa wyrobisk górniczych – Strzemiona oraz złącza odrzwi z kształtowników korytkowych – Badania wytrzymałościowe.
[19] PN-G-14050:1998 Betonity fundamentowe do obudowy odrzwiami z łuków korytkowych wyrobisk górniczych poziomych i mało nachylonych – Wymagania i badania.
[20] PN-G-15092:1999 Kotwie górnicze – Badania.
[21] PN-G-15533:1997 Górnicza obudowa indywidualna – Stojaki cierne – Wymagania i badania.
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Authors and Affiliations

Marek Rotkegel
1
ORCID: ORCID
Jerzy Korol
1
ORCID: ORCID
Dagmara Sobczak
1
ORCID: ORCID

  1. Central Mining Institute, Plac Gwarków 1, 40-166, Katowice, Poland
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Abstract

In November 1994 a first inventory of Tanaidacea from the Beagle Channel and at some stations of the Atlantic continental shelfwas obtained using epibenthic sledge samples. In total, 2175 specimens from 27 species of eight families of Tanaidomorpha and two families of Apseudomorpha were collected. Two species, Allotanais hirstutus (Beddard, 1886) and Apseudes heroae Sieg, 1986, strongly dominated this area. Generally low diversity and abundances were recorded for the western area of the Beagle Channel, while substantially higher values were reported at the eastern entrance on the Atlantic side of the Beagle Channel. Abundances slightly varied with depths, but not significantly.

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Authors and Affiliations

Anja Schmidt
Angelika Brandt
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Abstract

104 specimens of notothenioid fishes of five species (Patagonotothen longipes, P. tessellata, Champsocephalus esox, Cottoperca trigloides and Patagonotothen brevicauda) caught at two sites in the Beagle Channel (Magellanic sub-region, sub-Antarctica) were examined for the presence of thorny-headed worms (Acanthocephala). Representatives of three fish species, Patagonotothen longipes, P. tessellata, and Champsocephalus esox, were infected. Fishes caught at the eastern mouth of the channel were infected with 180 echinorhynchids representing three species, Aspersentis johni (the most numerous species), Heterosentis heteracanthus, and Hypoechinorhynchus magellanicus, and only 12 cystacanths of four polymorphids, Andracantha baylisi, Corynosoma sp., Corynosoma beaglense, and Corynosoma evae. Patagonotothen longipes was the most highly infected in the eastern mouth of the channel (prevalence 85%, maximum intensity 26). Aspersentis johni was the dominant parasite species in this host (prevalence 85%, mean abundance 4.00, maximum intensity 18) and H. heteracanthus was the sub-dominant one (prevalence 50%, mean abundance 2.60, maximum intensity 25). The infections of C. esox were the most diverse (six parasite species - three echinorhynchids and three polymorphids). Fish caught near the city of Ushuaia were infected only with six cystacanths of C. evae (intensity one). Taking into account the whole sample, C. evae was the most abundant polymorphid, represented by 10 of 18 specimens found. Three species, H. heteracanthus, A. baylisi and C. evae, have been previously reported from the low western Antarctic (H. heteracanthus also from the Kerguelen sub-region of sub-Antarctic), remaining four species seem to be endemics of the Magellanic sub-region of sub-Antarctic.

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Authors and Affiliations

Zdzisław Laskowski
Krzysztof Zdzitowiecki
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Abstract

In this paper, we present the methods to detect the channel delay profile and the Doppler spectrum of shallow underwater acoustic channels (SUAC). In our channel sounding methods, a short impulse in form of a sinusoid function is successively sent out from the transmitter to estimated the channel impulse response (CIR). A bandpass filter is applied to eliminate the interference from out-of-band (OOB). A threshould is utilized to obtain the maximum time delay of the CIR. Multipath components of the SUAC are specified by correlating the received signals with the transmitted sounding pulse with its shifted phases from 0 to 2π. We show the measured channel parameters, which have been carried out in some lakes in Hanoi. The measured results illustrate that the channel is frequency selective for a narrow band transmission. The Doppler spectrum can be obtained by taking the Fourier transform of the time correlation of the measured channel transfer function. We have shown that, the theoretical maximum Doppler frequency fits well to that one obtained from measurement results.

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Authors and Affiliations

Van Duc Nguyen
Tien Hoa Nguyen
Hoa Xuan Thi Ho
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Abstract

One of the main causes of damage to weirs regulating the flow of water in canals is local erosion of the bottom and banks. This is mainly due to the excessive kinetic energy of the stream flow and the uneven volumetric distribution of the water flow rate at the end of the strengthening. Due to this, 35–40% of hydraulic structures fail prematurely. The aim of the research was to determine the parameters of the spatial hydraulic jump arising behind the hydrotechnical structure and the rapid expansion of the cross-section. The research showed that the hydraulic jump with a curved cylinder in the plan is a spatial form and not only dissipates the energy of the stream, but also acts as a diffuser. With the stream expansion angle values in the range of 7–10°, a highly turbulent flow remains, which still has high kinetic energy at a distance from the end of the structure. At an angle of 25–27°, the flow is smooth, the velocity distribution is uniform across the width of the channel. In some cases, the forced expansion of the cross-section at the outflow of the weir favours the energy dissipation and uniform flow velocity distribution.
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Authors and Affiliations

Zhuzbay Kassymbekov
1
Abai Shinibaev
1
Galimzhan Kassymbekov
1

  1. Satbayev University, Satpayev Str., 22, Almaty, 050013, Kazakhstan
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Abstract

A flood occurs for many reasons, such as excessive rainfall, runoff coefficient, or an insufficient river channel capacity. The discharge flowing through the floodway depends on the maximum main river dimension that can be normalized. LU/LC changes are affected by runoff discharge, and runoff discharge is affected by the floodway design. The study dis-cusses the effect of land use (LU) or land cover (LC) changes and the design of floodway channel dimensions in the Kali Kemuning watershed, East Java Province, Indonesia. The Nakayasu synthetic unit hydrograph has been used to analyse the runoff discharge, and the Hydrologic Engineering Center’s River Analysis System software analysed the hydraulic proper-ties of river and floodway channels. Results show that the floodway channel design is determined by LU/LC conditions, and the river channel is normalized toward its maximum dimensions. Normalized channel depths and widths vary from 4 to 7 m and 16 to 46 m, respectively. The floodway channel is rectangular, with a bottom width of 10 m and depth of 4.5 m. With the runoff coefficient equal to 0.75, these normalized channel and floodway dimensions are suitable for the flood up to the 100-year return period runoff discharge.
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Authors and Affiliations

Agus Suharyanto
1
ORCID: ORCID
Yatnanta P. Devia
1
ORCID: ORCID
Indradi Wijatmiko
1
ORCID: ORCID

  1. Universitas Brawijaya, Faculty of Engineering, Civil Engineering Department, Jl. MT Haryono 167, Malang 65145, Jawa Timur, Indonesia
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Abstract

The ergodic channel capacity of wireless optical multiple-input multiple-output (MIMO) system with pulse position modulation (PPM) is investigated. The combined effects of atmospheric turbulence, atmospheric attenuation, pointing error and channel spatial correlation are taken into consideration. The expression of ergodic channel capacity is derived, and is further performed by Wilkinson approximation method for simplicity. The simulation results indicated that the strong spatial correlation has the greatest influence on the ergodic channel capacity, followed by pointing errors and atmospheric turbulence. Moreover, the ergodic channel capacity growth brought by space diversity only performs well under independent and weakly correlated channels. Properly increasing the size and spacing of the receiving apertures is an effective means of effectively increasing the ergodic channel capacity.
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Bibliography

[1] N. Joshi and P. K. Sharma, “Performance of wireless optical communication in S-distributed turbulence,” IEEE Photonic Technology Letters, vol. 28, no. 2, pp. 151-154, Oct. 2016. DOI: 10.1109/LPT.2015.2487605
[2] J. Anshul, and M. R. Bhatnagar, “Free-space optical communication: a diversity-multiplexing trade-off perspective,” IEEE Transactions on Information Theory, vol. 65, no. 2, pp. 1113-1125, 2019. DOI: 10.1109/TIT.2018.2856116.
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Authors and Affiliations

Minghua Cao
1
Yue Zhang
1
Zhongjiang Kang
1
Huiqin Wang
1

  1. School of Computer and Communication, Lanzhou University of Technology, Lanzhou, China
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Abstract

An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 ≤ JG ≤ 10 m/s and 0.02 ≤ JL ≤ 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight different inlet conditions and various mass splits at the junction. Comparisons were conducted between the present data and former correlations for the fully developed two-phase pressure drop in rectangular channels with similar sizes. Wide deviations were found among these correlations, and the correlations that agreed best with the present data were identified.
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Authors and Affiliations

Amr Mohamed Elazhary
Hassan M. Soliman
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Abstract

The paper presents two analytical solutions namely for Fanning friction factor and for Nusselt number of fully developed laminar fluid flow in straight mini channels with rectangular cross-section. This type of channels is common in mini- and microchannel heat exchangers. Analytical formulae, both for velocity and temperature profiles, were obtained in the explicit form of two terms. The first term is an asymptotic solution of laminar flow between parallel plates. The second one is a rapidly convergent series. This series becomes zero as the cross-section aspect ratio goes to infinity. This clear mathematical form is also inherited by the formulae for friction factor and Nusselt number. As the boundary conditions for velocity and temperature profiles no-slip and peripherally constant temperature with axially constant heat flux were assumed (H1 type). The velocity profile is assumed to be independent of the temperature profile. The assumption of constant temperature at the channel’s perimeter is related to the asymptotic case of channel’s wall thermal resistance: infinite in the axial direction and zero in the peripheral one. It represents typical conditions in a minichannel heat exchanger made of metal.
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Authors and Affiliations

Jarosław Mikielewicz
Witold Rybiński
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Abstract

Analysis of the state of-the-art in research of minichannel heat exchangers, especially on the topic of flow maldistribution in multiple channels, has been accomplished. Studies on minichannel plate heat exchanger with 51 parallel minichannels with four hydraulic diameters, i.e., 461 μm, 574 μm, 667 μm, and 750 μm have been presented. Flow at the instance of filling the microchannel with water at low flow rates has been visualized. The pressure drop characteristics for single minichannel plate have been presented along with the channels blockage, which occurred in several cases. The impact of the mass flow rate and channels’ cross-section dimensions on the flow maldistribution were illustrated.

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Authors and Affiliations

Paweł Dąbrowski
Dariusz Mikielewicz
Michał Klugmann
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Abstract

The paper is a presentation of an analysis concerning performance of a 12/8 dual-channel switched reluctance motor (DCSRM). Formulas constituting a base for a non-linear mathematical model of DCSRM are presented. Simulation and laboratory tests were carried out for the motor operating in the dual-channel and single-channel mode. The results of the field theory-based calculations are presented in the form of fluxes in individual phases expressed as functions of currents and a rotor position angle. The results of the computer simulations are shown as the static characteristics of fluxes and the torque as well as voltage, current, and torque waveforms. The results of the laboratory tests are also presented.

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Authors and Affiliations

Piotr Bogusz
Mariusz Korkosz
Jan Prokop
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Abstract

Queuing regime is one outstanding approach in improving channel aggregation. If well designed and incorporated with carefully selected parameters, it enhances the smooth rollout of fifth/next generation wireless networks. While channel aggregation is the merging of scattered TV white space (spectrum holes) into one usable chunk for secondary users (SU). The queuing regime ensures that these unlicensed users (SUs) traffic/ services are not interrupted permanently (blocked/dropped or forced to terminate) in the event of the licensed users (primary user) arrival. However, SUs are not identical in terms of traffic class and bandwidth consumption hence, they are classified as real time and non-real time SU respectively. Several of these strategies have been studied considering queuing regime with a single feedback queuing discipline. In furtherance to previous proposed work with single feedback queuing regime, this paper proposes, develops and compares channel aggregation policies with two feedback queuing regimes for the different classes of SUs. The investigation aims at identifying the impacts of the twofeedback queuing regime on the performance of the secondary network such that any SU that has not completed its ongoing service are queued in their respective buffers. The performance is evaluated through a simulation framework. The results validate that with a well-designed queuing regime, capacity, access and other indices are improved with significant decrease in blocking and forced termination probabilities respectively.

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Authors and Affiliations

Ebenezer Esenogho
Elie N. Mambou
Hendrik C. Ferreira
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Abstract

Aluminum profiles play an important role in civil engineering (facades, walls with windows) as well as in mechanical engineering (production lines, constructions of 3D printers and plotters). To ensure quick assembly, disassembly or changed the dimensions of constructions it is not possible to use such methods as welding, adhesive or riveting joints. The solution may be to use the so-called “popular lock”. It is a mechanism, the closure of which is caused by tightening of the conical screw, joining the “T” profile in the node. In order to properly design using the presented type of connection, it is necessary to know its strength and stiffness both in simple and complex loads states, also including imperfections. In the literature there is no information about the operation of the construction node with the so-called “popular lock”. The paper presents the results of experimental tests for connections subjected to uniaxial tensile test, paying special attention to the defects that may appear during the assembly. In the next step, a 3D solid connection model was created. Numerical simulations were performed in the Abaqus / Explicite program for both uniaxial tensile test and bending tests in two planes. Limit values of loads above which there is a plastic deformation of the material were determined. Determination of stiffness and strength of a single node allowed to make a simplified connector model. Using the numerical model, the analysis was performed taking into account the influence of imperfections on the work of the entire connection.

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Authors and Affiliations

P. Golewski
T. Sadowski

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