Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 6
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

This research proposes a method to enhance the payload message by embedding messages on the dilated edge areas by the Least Significant Bit (LSB) method. To add security aspects to messages, messages are not embedded directly on the LSB but encrypted with XOR operations with Most Significant Bit (MSB). The experimental results of the test in this study showed that the dilation process to some extent can increase the payload of 18.65% and the average bpp is 1.42 while maintaining the imperceptibilty quality of stego image with an average PSNR value of about 47 dB, SSIM is 0.9977 and MSE is 1.13.

Go to article

Authors and Affiliations

De Rosal Ignatius Moses Setiadi
Download PDF Download RIS Download Bibtex

Abstract

One of the problems limiting the use of vanadium as hydrogen permeable membranes is its high dilatation upon hydrogen dissolution in it. The information available for the dilatation coefficient value (Δυ/Ω) is contradictory, experimental information on the hydrogen solubility in vanadium within 100-1000 kPa at from 250 to 700°С is very limited. It does not enable to calculate the membrane dilatation. The article contains the measuring results for dilatation of strips made of vanadium foil 100 μm thick in a hydrogen atmosphere in the pressure range from 75 to 1000 kPa, temperatures from 250 to 700°С. The dilatation coefficient (Δυ/Ω) of polycrystalline vanadium was calculated based on the data obtained for dilatation and data previously published for the hydrogen concentration in the α-solid solution at 400°С. It is 0.165. Isobars for the temperature dependence of the hydrogen concentration in vanadium are calculated and constructed using the dilatation measuring results and the dilatation coefficient values. These data are agreed with theoretical and experimental data published previously. The limiting change in concentration and linear dimensions over the cross section of a hydrogen-permeable membrane from V was estimated at various temperatures and operating pressures at the membrane outlet based on the isobars plotted for temperature dependences of the CH/V. The conclusions are made on the optimal working conditions of Pd/V/Pd membranes when hydrogen is released from hydrogen-containing gas mixtures in accordance with Fick’s 1st law and data published previously for hydrogen concentration value at which solid hydrogen solutions in vanadium become brittle.
Go to article

Authors and Affiliations

A. Panichkin
1
ORCID: ORCID
A. Mamaeva
1
ORCID: ORCID
A. Kenzhegulov
1
ORCID: ORCID
Z. Karboz
1
ORCID: ORCID

  1. Satbayev University; Engineer of Laboratory Metallurgical Sciences, Institute of Metallurgy and Ore Beneficiation, 050010, Almaty City, Shevchenko str., 29/133, The Republic of Kazakhstan
Download PDF Download RIS Download Bibtex

Abstract

Objectives: In the article we describe the new, high frequency, 20 MHz scanning/Doppler probe designed to measure the flow mediated dilation (FMD) and shear rate (SR) close to the radial artery wall.

Methods: We compare two US scanning systems, standard vascular modality working below 12 MHz and high frequency 20 MHz system designed for FMD and SR measurements. Axial resolutions of both systems were compared by imaging of two closely spaced food plastic foils immersed in water and by measuring systolic/diastolic diameter changes in the radial artery. The sensitivities of Doppler modalities were also determined. The diagnostic potential of a high frequency system in measurements of FMD and SR was studied in vivo, in two groups of subjects, 12 healthy volunteers and 14 patients with stable coronary artery disease (CAD).

Results: Over three times better axial resolution was demonstrated for a high frequency system. Also, the sensitivity of the external single transducer 20 MHz pulse Doppler proved to be over 20 dB better (in terms of a signal-to-noise ratio) than the pulse Doppler incorporated into the linear array. Statistically significant differences in FMD and FMD/SR values for healthy volunteers and CAD patients were confirmed, p-values < 0:05. The areas under Receiver Operating Characteristic (ROC) curves for FMD and FMD/SR for the prediction CAD had the values of 0.99 and 0.97, respectively.

Conclusions: These results justify the usefulness of the designed high-frequency scanning system to determine the FMD and SR in the radial artery as predictors of coronary arterial disease.

Go to article

Authors and Affiliations

Andrzej Nowicki
Barbara Gambin
ORCID: ORCID
Wojciech Secomski
Zbigniew Trawiński
Michał Szubielski
Ryszard Tymkiewicz
Robert Olszewski
Download PDF Download RIS Download Bibtex

Abstract

‘Dhokra’ or ‘Dokra’ casting is a sophisticated cast metal craft tradition of the Indian subcontinent. It has been practiced by the countryfolk now since the Copper Age. It is a lost wax casting process in the hot clay mold. The technology is such sophisticated that it can produce up to 400 μm thin-walled hollow cast products with complicated and intricate shapes using Brass, Bronze, Copper, and other copper alloys. The investigation was for engraving Brass (2% lead) which is used by Dhokra artisans nowadays. In a field visit during dimensional analysis, one discrepancy was identified. The metal thicknesses of hollow castings are thicker than the thickness of the wax pattern. This cast metal dilation phenomenon is unusual. Shrinkage of metals compared to the pattern dimension is familiar in the casting world. The same abnormalities in the repeated investigation at different sites were observed. All the studies and experiments were organized to explain the reason hidden behind the phenomenon.
Go to article

Bibliography

[1] Mandal, B. & Datta P.K. (2010). Hot mold casting process of ancient east India and Bangladesh. China Foundry. 7(2), 171-177.
[2] Mukherjee, D. (2016). A comparative study of dokra metal craft technology and harappan metal craft technology. Heritage: Journal of Multidisciplinary Studies in Archaeology. 4, 757-768.
[3] Roy, S., Pramanick, A.K. & Datta, P.K. (2020). Precise filling time calculation of thin walled investment casting in hot mold. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 42(10), 1-11. https://doi.org/10.1007/s40430-020-02634-6.
[4] Dong, Y.W., Li, X.L., Zhao, Q., Yang, J. & Dao, M. (2017). Modelling of shrinkage during investment casting of thin-walled hollow turbine blades. Journal of Materials Processing Technology. 244, 190-203. https://doi.org/10.1016/j.jmatprotec.2017.01.005.
[5] Cannell, N., Sabau, A.S. (2005). Predicting pattern tooling and casting, dimensions for investment casting, phase II. Final Technical Report, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
[6] Kroma, A. & Brzęk, P. (2021). Influence of mould material on the mechanical properties of wax models. Archive of Foundry Engineering. 21(3), 48-52. DOI: 10.24425/afe.2021.138664.
[7] Stefanescu, D. S. (2002). Science and engineering of casting solidification. New York: Springer Scienee.
[8] Garbacz-Klempka, A., Suchy, J.S., Kwak, Z., Tokarski, T., Klempka, R. & Stolarczyk, T. (2018). Study of investment casting technology from bronze age. Casting workshop in grzybiany (Southwest Poland). Archives of Metallurgy and Materials. 63(2), 615-624. DOI: 10.24425/122385.
[9] Roy, S., Pramanick, A.K. & Datta, P.K. (2017). Kinetics of liquid metal flow in gating design of investment casting production. Slévárenství. 5-6, 149-154.
[10] Raza, M. (2015). Experimental study of the filling of thin-walled investment castings In 17-4ph stainless steel. Metall Foundry Engineering. 41(2), 85-98. DOI: https://doi.org/10.7494/mafe.2015.41.2.85.
[11] Chang, S. & Stefanescu, D.M. (1996). A model formacrosegregation and its application to Al-Cu castings. Metallurgical and Materials Transaction A. 27(9), 2708-2721.
[12] Roy, S., Pramanick, A.K., Datta P.K. (2021). Quality analysis of tribal casting products by topsis for different gating system. In IOP Conference Series: Materials Science and Engineering, February, 2021 (p. 012014). IOP Publishing. DOI: 10.1088/1757-899X/1080/1/012014.
[13] Stefanescu, D.M.(1998). Casting. ASM handbook Volume: 15. 409-413. ASM International.
[14] Roy, S., Kr Pramanick, A., Kr Datta P. (2022). The effect of gating system on quality of traditional rural metal castings of india. Rrecent trends in industrial and production engineering. Lecture notes in mechanical engineering. (pp. 267-278). Singapore: Springer. https://doi.org/10.1007/978-981-16-3135-1_27. [15] Austral Wright Metals-Ferrous, Non-Ferrous and High Performance Alloys (2008, August). Metal alloys-properties and applications of brass and brass alloys. Retrieved May, 30 2022, from https://www.azom.com/article.aspx?ArticleID=4387
[16] Extra High Leaded Brass UNS C35600. Retrieved May, 30 2022, from https://www.azom.com/article.aspx?ArticleID=6389
[17] Mandal, B. & Datta, P. K. (2010). Understanding alloy design principles and cast metal technology in hot molds for medieval Bengal. Indian Journal of History of Science. 45(1), 101-140.
[18] Rao, P.N. (2019). Manufacturing technology. Vol.- I, (5th ed.) India: McGraw Hill Education.
[19] Horáček, M. (2005). Accuracy of investment casting. Archives of Foundry. 5(15). 121-137.
[20] Indian Minerals Yearbook 2015 (Part- III : Mineral Reviews), (2017, February) Retrieved May 28, 2022, from https://ibm.gov.in/writereaddata/files/02282017165033IMYB2015_Kaolin_28022015_Adv.pdf.
[21] Thampi, C.J. (2013). Soils Of Bankura District (West Bengal) For Land Use Planning. National Bureau of Soil Survey & Land Use Planning, India.
[22] RSP Green Development And Laboratories PVT. LTD, (July 2018) District Survey Report of Bankura District. India.
[23] Chakraborty A. K. (2014). Phase transformation of kaolinite clay. (1st ed.), New York, New Delhi: Springer. DOI 10.1007/978-81-322-1154-9.
[24] Hyslop, A. McMurdo, (1938). The thermal expansion of some clay mineral. Transactions and journal of the British Ceramic Society. 37, 180-186.
[25] Heindl, R.A. & Meng, L.E. (1939). Length changes and endothermic and exothermic effects during heating of flint and aluminous clays. Journal of Research of the National Bureau of Standards. 23(9), 427-441.
[26] Thiel. J. (2011). Thermal expansion of chemically bonded silica sands. AFS Transations - American Foundry Society. 11-116, 1-10.
[27] ISO 1: 2016: Geometrical product specifications (GPS)—standard reference temperature for the specification of geometrical and dimensional properties. https://www.iso.org/standard/67630.html.
[28] Anggono, J. (2005). Mullite ceramics: its properties, structure, and synthesis. Jurnal Teknik Mesin. 7(1), 1-10.
[29] Cannell, N., Sabau, A.S. (2007). Predicting pattern tooling and casting, dimensions for investment casting, phase III. Final Technical Report, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Go to article

Authors and Affiliations

S. Roy
1
ORCID: ORCID
A.K. Pramanick
1
P.K. Datta
1
ORCID: ORCID

  1. Dept. of Metallurgical and Material Engineering, Jadavpur University, Kolkata-700032, India
Download PDF Download RIS Download Bibtex

Abstract

Full-length bonded bolts are widely used in deep mining engineering and an in-depth understanding of their mechanical characteristics under complex and high ground stress conditions is of great significance for deep roadway support systems. Based on a quantitative GSI rating system of surrounding rocks and rock nonlinear dilatancy angle model, a nonlinear dilatancy angle model suitable for jointed rocks was developed. The Hoek–Brown strain-softening model parameters were transformed into equivalent Mohr–Coulomb strength parameters, and a numerical model of the deep roadway was constructed using FLAC 3�� numerical simulation software as a tool. The force characteristics of fulllength bonded anchors under different constitutive model and dilatancy angle model conditions were analyzed, and the effects of different lengths of anchors on the stability of the surrounding rock were studied. The obtained results revealed a big difference between the axial forces of bolts calculated by strain-softening and ideal elastic-plastic models. It was also found that bolt shear force was less influenced by the strain-softening behaviors of surrounding rocks. Dilatancy angle greatly affected bolt axial force. Therefore, if the dilatancy angle was neglected, great errors would be created in the calculation results of supporting structure designs. The nonlinear dilatancy angle model of jointed rock masses more accurately captured the stress properties of bolts after field monitoring and analysis. The findings of the study can serve as a guide for calculating the stability of surrounding rocks in deep mining engineering.
Go to article

Authors and Affiliations

Zenghua Lin
1
ORCID: ORCID

  1. School of Civil Engineering, University of Science and Technology Liaoning, China

This page uses 'cookies'. Learn more