In this paper, the problem of free convection boundary layer flow on a horizontal circular cylinder in a nanofluid with viscous dissipation and constant wall temperature is investigated. The transformed boundary layer equations are solved numerically using finite difference scheme namely the Keller-box method. Numerical solutions were obtained for the reduced skin friction coefficient, Nusselt number and Sherwood number as well as the velocity and temperature profiles.The features of the flow and heat transfer characteristics for various values of the Brownian motion parameter, thermophoresis parameter, Lewis number and Eckert number were analyzed and discussed.
Bacteria exist widely in a diversity of natural environments. In order to survive adverse conditions such as nutrient depletion, biochemical and biological disturbances, and high temperature, bacteria have developed a wide variety of coping mechanisms. Temperature is one of the most important factors that can enhance the expression of microbial proteins. This study was conducted to investigate how outer membrane proteins (OMPs) of the bacterium Shigella flexneri respond to stress, especially during fever when the host's body temperature is elevated.
The heat and mass transfer of steady magnetohydrodynamics of dusty Jeffrey fluid past an exponentially stretching sheet in the presence of thermal radiation have been investigated. The main purpose of this study is to conduct a detailed analysis of flow behaviour of suspended dust particles in non-Newtonian fluid. The governing equations hav been converted into dimensionless form, and then solved numerically via the Keller-box method. The expression of Sherwood number, Nusselt number and skin friction have been evaluated, and then displayed in tabular forms. Velocity, temperature and concentration profiles are presented graphically. It is observed that large value of dust particles mass concentration parameter has reduced the flow velocity significantly. Increase in radiation parameter enhances the temperature, whereas the increment in Schmidt number parameter reduces the concentration.
Coral reef research has predominantly focused on the effect of temperature on the breakdown of coral-dinoflagellate symbioses. However, less is known about how increasing temperature affects the establishment of new coral-dinoflagellate associations. Inter-partner specificity and environment-dependent colonization are two constraints proposed to limit the acquisition of more heat tolerant symbionts. Here, we investigated the symbiotic dynamics of various photosymbionts in different host genotypes under "optimal" and elevated temperature conditions. To do this, we inoculated symbiont-free polyps of the sea anemone Exaiptasia pallida originating from Hawaii (H2), North Carolina (CC7), and the Red Sea (RS) with the same mixture of native symbiont strains (Breviolum minutum, Symbiodinium linucheae, S. microadriaticum, and a Breviolum type from the Red Sea) at 25 and 32 °C, and assessed their ITS2 composition, colonization rates, and PSII photochemical efficiency (Fv/Fm). Symbiont communities across thermal conditions differed significantly for all hosts, suggesting that temperature rather than partner specificity had a stronger effect on symbiosis establishment. Overall, we detected higher abundances of more heat resistant Symbiodiniaceae types in the 32 °C treatments. Our data further showed that PSII photophysiology under elevated temperature improved with thermal pre-exposure (i.e., higher Fv/Fm), yet, this effect depended on host genotype and was influenced by active feeding as photochemical efficiency dropped in response to food deprivation. These findings highlight the role of temperature and partner fidelity in the establishment and performance of symbiosis and demonstrate the importance of heterotrophy for symbiotic cnidarians to endure and recover from stress.
This paper presents the temperature characteristics of silicon nanowire transistors (SiNWTs) and examines the effect of temperature on transfer characteristics, threshold voltage, I(ON)/I(OFF) ratio, drain-induced barrier lowering (DIBL), and sub-threshold swing (SS). The (MuGFET) simulation tool was used to investigate the temperature characteristics of a transistor. The findings reveal the negative effect of higher working temperature on the use of SiNWTs in electronic circuits, such as digital circuits and amplifiers circuits, because of the lower I(ON)/I(OFF) ratio, higher DIBL, and higher SS at higher temperature. Moreover, the ON state is the optimum condition for using a transistor as a temperature nano-sensor.
The drying of Piper betle Linn (betel) leaf extract using a lab scale spray dryer was simulated using Computational Fluid Dynamics (CFD). Three different turbulent models (standard k-ε, RNG k-ε and realizable k-ε) were used in the present study to determine the most suitable model for predicting the flow profile. Parametric studies were also conducted to evaluate the effect of process variables on the final moisture content. Four different initial droplet sizes (36, 79, 123 and 166 μm) were tested with four sets of combination of hot air temperature (140 and 160°C) and feed rate (4, 9.5 and 15 ml/min). It was found that standard k-ε is the most suitable turbulent model to predict the flow behaviour Moreover, the lowest final moisture content present in samples was obtained at 140°C and a feed rate of 15.0 ml/min.
The glow curve in TLD-100 was compared by applying long preheat time, short preheat time
techniques and without preheat technique before the TLD readout. Fading effect of the TLD signal
upon certain storage time with long preheat time (100°C, 10 minutes using the oven) and short
preheat time techniques (100°C, 10 seconds using the reader) were also studied. 15 TLD-100 chips
were used with 3 of the TLD chips were used for measuring background radiation. 12 TLD chips
were annealed, irradiated, preheated long and short preheat time techniques) and analyzed. The TL
signals output from TLD chips of without preheated were used as the control. Two sets of data were
taken using TLD chips irradiated with 6 MV and 10 MV photon beams. TL signal output was
recorded the highest for short preheat time, followed by long preheat time and no preheating. The
TL signal loss upon certain storage time was also reduced when short preheat time technique was
applied. By applying long preheat time technique the low temperature peak in the glow curve was
completely removed for both energies. Whereas, TLD chips exposed to 6 MV and with short preheat
time technique the low temperature peak did not disappear completely but decreased in intensity as
compared to the control data by 19.80%, 37.69%, 48.19% and 100% at 24, 48, 72 and 96 hours
after exposure prior to readout, respectively. Meanwhile, for 10 MV photon beam with short
preheat time, the small peak intensity was reduced by 19.58% for readout at 24 hours after
irradiation and 100% for 48,72 and 96 hours delayed time prior to readout. It was observed that
the TLD-100 was highly dependent on preheat heating time before readout. Short preheat time
technique was able to reduce post irradiation fading of TLD-100 dosimeters
A study has been conducted on pink guava juice (PGJ) fouling deposit. Several ex-situ experimental rigs were set-up to obtain PGJ fouling deposit, while the best ex-situ experimental rig was also selected. PGJ was heated at 93°C and its fouling deposit was obtained after 1 hour of heating. Then, it was used for the ex-situ cleaning study at 1 litre min-1, at several temperatures (70, 80 and 90°C), and in some chemical concentrations (1.6 v/v% of Maxiclean CP6 or 0.325 % OH-; 1.8 v/v% of Maxiclean CP6 or 0.369 % OH-; 2.0 v/v% of Maxiclean CP6 or 0.44 % OH-). The best cleaning combinations were investigated. Carbohydrate is the main content in the fouling deposit. The morphology of the deposit was studied using SEM and it showed an aggregated structure. The cleaning process improved as the temperature increased with the increasing of the chemical solution concentration. The shortest cleaning time was 40 minutes, for cleaning using 2.0 v/v % of Maxiclean CP6 (0.44 % OH-) at 90°C.
This paper discuss thermal comfort studies of an under air conditioning in hot and humid climate which at one of the higher institution in East Coast of Malaysia. Indoor thermal environment is important as it affects the health and productivity of building occupants. The paper reports on an experimental investigation of indoor thermal comfort characteristics under the control of air conditioning. Firstly, the well known Fanger’s thermal comfort model was simplified for the current experimental investigation. This is followed by reporting the experimental results of indoor thermal comfort characteristics under the control of temperature, with eight different of temperatures which are 22oC to 29oC. Finally, indoor thermal comfort was merely affected by the increment ventilation and outdoor climate. PMV value was higher when near from the window because of the effects of the wall radiations and the metabolic heat.
Extract of mengkudu was heated using a bench-top tube heat exchanger at 30, 50, 70 and 90 o C for 0, 5, 10 and 15 min residence time. The treated mengkudu extract was then measured for pH, L * , a * , b * color parameters, clarity, viscosity and total polyphenol content. Results show that heating using temperature of 30 to 90 o C for 5 to 15 mins significantly (p
The microstructure, tensile fracture and creep fracture of as-cast beta phase contained γ-TiAl with nominal composition of Ti-48Al-4Cr (at.%) was investigated. The effect of beta phase on tensile and creep strength was determined from fracture analysis. Tensile test were performed at room temperature whereas constant load tensile creep test were performed at temperature 800 0 C and initial stress of 150MPa. Initial as-cast microstructure, microstructure and fracture surface after tensile and creep test were examined using scanning electron microscopy technique. Analysis shows brittle fracture after room temperature tensile test whereas ductile fracture after high temperature creep test. The role of beta phase was discussed. It is concluded that beta phase is sensitive to temperature and detrimental at both room and high temperature.
This study analysed mixed convection heat transfer for thermally developing flow in a side heated square duct with varying inclination angles. The test section consists of one-side heated isothermal wall and three adiabatic walls. The inclination angle varied from 00C, and heat flux ranging from 252 W/m2C to 100o30o 858 to 1788 and the wall surface emissivity was considered to be 0.05 and 0.85. Flow visualizations were carried out to obtain the flow structure of natural convection and mixed convection for three inclination angles. The variation of surface temperature along the length of the test section was studied to calculate the convective Nusselt number. The result showed that the heat transfer enhancement and convective Nusselt number was significantly affected by the variations of inclination angle, flow velocity, Reynolds number, and the surface radiation. It was also observed that the increase in the inclination angle improved convection rate and hence significantly enhanced heat transfer. to 200, with hot wall temperature ranging from to 872 W/m2
XRF analysis was done on a local zircon samples and the result shows it has a high Fe, Th and U content. The high Fe content in Malaysian zircon had made the mineral to be classified as of a low-grade zircon. Presence of Fe in this mineral may be resulted from clay mineral coating found on the zircon surface. Chemical leaching technique was used for the removal of this Fe and the study also shows that a 600 o C heat pretreatment stage is important for the effectiveness of this process. Other parameters studied are the HCl concentration, leaching temperature and time. By using the optimum leaching parameters, the Fe content had been reduced to 0.049% and thus qualified it to be categorised as a premium grade zircon.
Scholars have opined that the courtyard is a passive architectural design element and
that it can act as a microclimate modifier provided that its design requirements are not
ignored. But despite the assertions, empirical studies on the microclimatic
performance of a fully enclosed courtyard house and the non-courtyard house seems
to be deficient, and the assumption that the Courtyard is a passive architectural design
element needs to be substantiated. Therefore, the purpose of this study is to
investigate the microclimatic performance of a fully enclosed courtyard and noncourtyard
residential buildings. The main objective is to compare their microclimatic
performances in other to draw a conclusion on the best option. Three Hobo Weather
Data Loggers were used to collect climatic data in the buildings, and the third one was
situated in the outdoor area as a benchmark. The climatic variables investigated are;
air temperature and relative humidity. The fully enclosed courtyard residential building
is seen to have a better air temperature difference of 2 oC to 4 oC and the relative
humidity of 2 % to 6 %. In conclusion, the fully enclosed courtyard residential building
has confirmed a more favorable microclimatic performance, and future studies
towards its optimization are recommended.
Top-Oil Temperature (TOT) is one of the basic components to estimate the Hot-Spot temperature (HST) of the transformers. This paper presents an alternative TOT model based on the heat transfer theory that utilises Nonlinear Thermal Resistance (NTR) and Lumped Capacitance (LC) approaches. It is applied in a thermal-electrical analogy and the heat transfer equivalent equation is determined. This model is tested on a measured TOT of 250 MVA ONAF and 400 MVA ONAF transformers obtained from IEC 60076-7 and previous research. A comparison of TOT is carried out with the existing models IEC 60076-7 exponential and IEEE Loading Guide clause 7 methods. It is found that the thermal model based on the NTR and LC approach could determine the measured TOT closer than the existing methods available in the standards.
The major aim of this research was to investigate the addition of BPSC on the physical and rheological properties of asphalt binder. In this study, addition of five different percentages of BPSC compositions were studied, namely (2, 4, 6 and 8%). The impact of modifier on the rheological and physical properties was determined using conventional tests, such as softening point, ductility and penetration, and measurements from a dynamic shear rheometer. Based on the results, it was observed that the addition of BPSC has a significant impact on the rheological properties of asphalt binder and would improve rutting resistance at high temperatures. Meanwhile, results related to physical properties indicated that a decrease in penetration and increase in softening points results in stiffness of BPSC. The results showed that BPSC reduced temperature susceptibility and increased stiffness and elastic behaviour in comparison to unmodified asphalt binder. This means BPSC would increase the resistance of permanent deformation (rutting). Finally, BPSC could be considered as an appropriate additive to modify the properties of asphalt binder.
Functionally graded NiTi structures benefit from the combination of the smart properties of NiTi and those of functionally graded structures. This article provides experimental data for thermomechanical deformation behaviour of microstructurally graded, compositionally graded and geometrically graded NiTi alloy components, related to the research article entitled "Functionally graded shape memory alloys: design, fabrication and experimental evaluation" (Shariat et al., 2017) [1]. Stress-strain variation of microstructurally graded NiTi wires is presented at different heat treatment conditions and testing temperatures. The complex 4-way shape memory behaviour of a compositionally graded NiTi strip during one complete thermal cycle is demonstrated. The effects of geometrical design on pseudoelastic behaviour of geometrically graded NiTi plates over tensile loading cycles are presented on the stress-strain diagrams.
This paper discusses the effect of jet impingement of water on a photovoltaic thermal (PVT) collector and compound parabolic concentrators (CPC) on electrical efficiency, thermal efficiency and power production of a PVT system. A prototype of a PVT solar water collector installed with a jet impingement and CPC has been designed, fabricated and experimentally investigated. The efficiency of the system can be improved by using jet impingement of water to decrease the temperature of the solar cells. The electrical efficiency and power output are directly correlated with the mass flow rate. The results show that electrical efficiency was improved by 7% when using CPC and jet impingement cooling in a PVT solar collector at 1:00 p.m. (solar irradiance of 1050 W/m² and an ambient temperature of 33.5 °C). It can also be seen that the power output improved by 36% when using jet impingement cooling with CPC, and 20% without CPC in the photovoltaic (PV) module at 1:30 p.m. The short-circuit current ISC of the PV module experienced an improvement of ~28% when using jet impingement cooling with CPC, and 11.7% without CPC. The output of the PV module was enhanced by 31% when using jet impingement cooling with CPC, and 16% without CPC.
Numerical results are presented for the effect of first order chemical reaction and thermal radiation on mixed convection flow of Casson fluid in the presence of magnetic field. The flow is generated due to unsteady nonlinearly stretching sheet placed inside a porous medium. Convective conditions on wall temperature and wall concentration are also employed in the investigation. The governing partial differential equations are converted to ordinary differential equations using suitable transformations and then solved numerically via Keller-box method. It is noticed that fluid velocity rises with increase in radiation parameter in the case of assisting flow and is opposite in the case of opposing fluid while radiation parameter has no effect on fluid velocity in the forced convection. It is also seen that fluid velocity and concentration enhances in the case of generative chemical reaction whereas both profiles reduces in the case of destructive chemical reaction. Further, increase in local unsteadiness parameter reduces fluid velocity, temperature and concentration. Over all the effects of physical parameters on fluid velocity, temperature and concentration distribution as well as on the wall shear stress, heat and mass transfer rates are discussed in detail.