Jizhao Liu^1,2, Jiang Hui^1,2,*, Zhaofa Wang^1,2

Sound & Vibration, Vol.58, pp. 151-169, 2024, DOI:10.32604/sv.2024.045193

Abstract User authentication on smart devices is crucial to protecting user privacy and device security. Due to the development of emerging attacks, existing physiological feature-based authentication methods, such as fingerprint, iris, and face recognition are vulnerable to forgery and attacks. In this paper, GestureID, a system that utilizes acoustic sensing technology to distinguish hand features among users, is proposed. It involves using a speaker to send acoustic signals and a microphone to receive the echoes affected by the reflection of the hand movements of the users. To ensure system accuracy and effectively distinguish users’ gestures, a second-order differential-based phase extraction method… More >

Gintautas Miliauskas^*, Stasys Sinkunas, Kristina Norvaisiene, Kestutis Sinkunas

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-6, 2012, DOI:10.5098/hmt.v3.2.3006

Abstract Water droplet evaporation process is numerically modelled under various heat and mass transfer conditions. Regularities of heat transfer process interaction are examined. Modelling in this work was performed using the combined analytical – numerical method to investigate heat and mass transfer in the two-phase droplets-gas flow system. The influence of forced liquid circulation on the thermal state of droplets is taken into account by the effective coefficient of thermal conductivity. Calculating the rate of droplet evaporation and the intensity of convective heating, the influence of the Stefan’s hydrodynamic flow is taken into account. Balancing energy fluxes in the droplet to… More >

Arvind Pattamatta^a,*, Ghanshyam Singh^b

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-11, 2012, DOI:10.5098/hmt.v3.2.3005

Abstract The present study deals with the assessment of different turbulence models for heated wall jet flow. The velocity field and thermal characteristics for isothermal and uniform heat flux surfaces in the presence of wall jet flow have been predicted using different turbulence models and the results are compared against the experimental data of Wygnanski et al. (1992), Schneider and Goldstein (1994), and AbdulNour et al. (2000). Thirteen different turbulence models are considered for validation, which include the Standard k-ε (SKE), Realizable k-ε (RKE), shear stress transport (SST), Sarkar & So (SSA), v ² -f, Reynolds stress Model (RSM), and Spalart… More >

Z. Aouachria^a,*, F. Rouichi^a, D. Haddad^b

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-6, 2012, DOI:10.5098/hmt.v3.2.3004

Abstract Natural convection flow past a vertical porous plate in a porous medium is studied numerically, by taking into account the Dufour and Soret effects. The similarity equations of the problem considered are obtained by using usual similarity technique. This system of ordinary differential equations, which are solved numerically by using the Nachtsheim -Swigerst hooting iteration technique together with a sixth order Runge-Kutta integrations scheme. The results show that Soret and Dufour effects do not appreciably influence the velocity, temperature and concentration fields, but rather only tend to increase the mass and energy flux due to the added contributions. More >

Nikola Stosic^**, Ian K. Smith, Ahmed Kovacevic

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-7, 2012, DOI:10.5098/hmt.v3.2.3003

Abstract Due to fast rotation of screw compressor rotors, temperature is uniform in the rotor cross section and temperature field is a function of the axial coordinate only. Apart of that the rotors in one cross section the rotors are simultaneously heated by hot gas on one side while cooled at another side by cold gas. As a result of identification of the main modes of heat transfer both in the rotors and between the rotors and their surroundings and the relative significance of each, a novel procedure is suggested to cool the rotors by injection of minute quantities of a… More >

Frantisek Kavicka^a,*, Jana Dobrovska^b, Karel Stransky^a, Bohumil Sekanina^a, Josef Stetina^a

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-9, 2012, DOI:10.5098/hmt.v3.2.3002

Abstract Corundo-baddeleyit material (CBM) – EUCOR – is a heat- and wear-resistant material even at extreme temperatures. This article introduces an original numerical model of solidification and cooling of this material in a non-metallic mold. The second, cooperating model of chemical heterogeneity and its application on EUCOR samples prove that the applied method of measuring the chemical heterogeneity provides the detailed quantitative information on the material structure and makes it possible to analyze the solidification process. The verification of both numerical models was conducted on a real cast 350 x 200 x 400 mm block. More >

Yunpeng Ren, J. K. Chen^*, Yuwen Zhang

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-7, 2012, DOI:10.5098/hmt.v3.2.3001

Abstract Heat transfer in a copper film irradiated by a femtosecond (fs) laser pulse train and by an integrated dual laser beam of a nanosecond pulse with a fspulse train was studied using the semi-classical two-temperature model. The critical point model with three Lorentzian terms was employed to characterize transient optical properties for the laser energy deposition. The effects of pulse number and separation time on the thermal response were investigated. The results showed that with the same total energy in a fs-pulse train, more pulses for shorter separation time, e.g., 1 ps, and fewer pulses for longer separation time, e.g.,… More >

Milind S. Patil^a,*, Ramchandra S. Jahagirdar^b, Eknath R. Deore^a,†

Frontiers in Heat and Mass Transfer, Vol.3, No.3, pp. 1-5, 2012, DOI:10.5098/hmt.v3.3.3008

Abstract Convection heat loss inevitably occurs in receivers of high concentrating solar concentrators. All the concentrators are need to be tack during the operation and hence the position of the receiver is changing continually. The angle of the receiver axis will then play an important role in the heat loss. Few researches were reported for the hemispherical cavity receivers numerically. The paper presented here is an experimental investigation natural convection heat loss from hemispherical cavity receiver. Cavity receiver of diameter 540 mm was tested. It is observed that the heat loss was minimum for 90° and maximum for 0°. More >

Ahmad Najjaran¹, Ali R. Tahavvor, Abdolkarim Najjaran, Mohammad A. Ahmadfard

Frontiers in Heat and Mass Transfer, Vol.3, No.3, pp. 1-6, 2012, DOI:10.5098/hmt.v3.3.3007

Abstract In this paper, external radiation heat transfer coefficient and flux of a standing human body model are calculated for different emissivity coefficients and various temperature differences. To do this, a standing human body sample is designed in such a way that hands and feet are totally open and stretched. Soles are in contact with the ground and so do not have heat transfer. The results are extracted by weighted average method. Despite the existence of the air around the body in reality, the convection heat transfer of human body with the surrounding air is neglected in order to prevent errors… More >

Arafat A. Bhuiyan^a,1, A. K. M. Sadrul Islam^a, M. Ruhul Amin^b

Frontiers in Heat and Mass Transfer, Vol.3, No.3, pp. 1-9, 2012, DOI:10.5098/hmt.v3.3.3006

Abstract This numerical analysis presents the airside performance of a wavy fin-and-tube heat exchanger having 4 row configurations considering steady, incompressible and 3D flow using Commercial CFD Code ANSYS CFX 12.0. Results are presented in the form of friction factor (f), Colburn factor (j) and efficiency index (j/f). The numerical procedure has been validated by comparison with published numerical and experimental results and good agreement has been observed. A series of numerical calculations have been carried out in order to analyze the influence of various geometric characteristics on different fields as well as on the heat transfer and pressure drop and… More >