Thermal performance prediction models for a pulsating heat pipe using Artificial Neural Network (ANN) and Regression/Correlation Analysis (RCA)

Pulsating heat pipe (PHP) is one of the prominent research areas in the family of heat pipes. Heat transfer and fluid flow mechanism associated with PHP are quite involved. The analytical models are simple in nature and limited in scope and applicability. The regression models and Artificial Neural Network (ANN) are also limited to a number of input parameters, their ranges and accuracy. The present paper discusses the thermal performance prediction models of a PHP based on ANN and RCA approach. Totally 1652 experimental data are collected from the literature (2003–2017). Nine major influencing input variables are considered for the first time to develop the prediction models. Feed-forward back-propagation neural network is developed and verified. Backward regression analysis is used in RCA-based regression model. Linear and power-law regression correlations are developed for input heat flux in terms of dimensionless Kutateladze (Ku) number, which is a function of Jakob number (Ja), Morton number (Mo), Bond number (Bo), Prandtl number (Pr) and geometry of a PHP. The prediction accuracy of present regression models (R²?=?0.95) is observed to be better as compared with literature-based correlations.     

Insight into Phase Transition,Electronic, Magnetic,Mechanical, and Thermodynamic Properties of TbTe: a DFT Investigation

Theoretical investigation on TbTe for its structural, electronic, magnetic, and thermodynamic stuffs has been carried within density functional theory (DFT) as implemented in WIEN2K code. TbTe was found stable in ferromagnetic phase. The calculated ground-state parameters were found in a good agreement with the experimental data. The compound was found to have a structural stability in cubic B1 (NaCl-type structure) phase, but under the application of high pressure (at 27 GPa), it undergone to B2 (CsCl-type structure) phase of pressure. The second-order elastic constants and mechanical properties like Young’s modulus, Shear modulus, Poisson ratio, Cauchy pressure (C₁₂–C₄₄), and Pugh’s ratio (B/G) were calculated. The present calculations confirmed the ductile nature of TbTe. Further, the thermodynamic investigations have been carried using quasi-harmonic Debye approximation. We have calculated the pressure and temperature dependence of Debye temperature (??_D), bulk modulus (B), thermal expansion (α), heat capacities (C_V), and entropy (S) in the temperature range of 0 to 1000 K and pressure range of 0 to 25 GPa.     

Activity of quassinoids as antifeedants against aphids

A series of quassinoids was tested for antifeedant activity against the aphidMyzus persicae (Hemiptera, Aphididae). Isobrucein B, brucein B and C, glaucarubinone, and quassin decreased feeding at concentrations down to 0.05% and isobrucein A was effective at 0.01%. Only quassin showed no phytotoxic effects and is therefore the most promising compound for further development.     

Effect of Annealing Temperature on Flowerlike Cu<Subscript>3</Subscript>BiS<Subscript>3</Subscript> Thin Films Grown by Chemical Bath Deposition

For widespread application of thin-film photovoltaic solar cells, synthesis of inexpensive absorber material is essential. In this work, deposition of ternary Cu₃BiS₃ absorber material, which contains abundant and environmentally benign elements, was carried out on glass substrate. Flowerlike Cu₃BiS₃ thin films with nanoflakes as building block were formed on glass substrate by chemical bath deposition. These films were annealed at 573 K and 673 K in sulfur ambient for structural improvement. Their structure was characterized using Raman spectroscopy, as well as their surface morphological and optical properties. The x-ray diffraction profile of as-deposited Cu₃BiS₃ thin film revealed amorphous structure, which transformed to orthorhombic phase after annealing. The Raman spectrum exhibited a characteristic peak at 290 cm^?1. Scanning electron microscopy of as-deposited Cu₃BiS₃ film confirmed formation of nanoflowers with diameter of around 1052 nm. Wettability testing of as-deposited Cu₃BiS₃ thin film demonstrated hydrophobic nature, which became hydrophilic after annealing. The measured ultraviolet–visible (UV–Vis) absorption spectra of the Cu₃BiS₃ thin films gave an absorption coefficient of 10⁵ cm^?1 and direct optical bandgap of about 1.42 eV after annealing treatment. Based on all these results, such Cu₃BiS₃ material may have potential applications in the photovoltaic field as an absorber layer.     

Accidental gamma dose measurement using commercial glasses

Commercial glasses have been investigated for their application in accidental gamma dose measurement using Thermoluminescent (TL) techniques. Some of the glasses have been found to be sensitive enough that they can be used as TL dating material in radiological accident situation for gamma dosimetry with lower detection limit 1 Gy (the dose significant for the onset of deterministic biological effects). The glasses behave linearly in the dose range 1-25 Gy with measurement uncertainty +/- 10%. The errors in accidental dose measurements using TL technique are estimated to be within +/- 25%. These glasses have shown TL fading in the range of 10-20% in 24 h after irradiation under room conditions; thereafter the fading becomes slower and reaches upto 50% in 15 d. TL fading of gamma-irradiated glasses follows exponential decay pattern, therefore dosimetry even after years is possible. These types of glasses can also be used as lethal dose indicator (3-4 Gy) using TL techniques, which can give valuable inputs to the medical professional for better management of radiation victims. The glasses are easy to use and do not require lengthy sample preparation before reading as in case of other building materials. TL measurement on glasses may give immediate estimation of the doses, which can help in medical triage of the radiation-exposed public.     

Development of ashless multifunctional additives from cashew nutshell liquid

Aminodi(alkylphenyl) phosphorodithioates have been synthes‐ised by the condensation of di (alkylphenyl) phosphorodithioic acid, which was derived from a renewable, biodegradable, low‐cost, naturally occurring vegetable product, cashew nutshell liquid, with various amines. These ashless aminodi (alkyl‐phenyl) phosphorodithioates have been evaluated as anti‐oxidant, antiwear, friction‐modifying, and extreme‐pressure additives in lubricant compositions.     

An ESCA study of the effectiveness of antiwear and extreme‐pressure additives based on substituted phosphorodithioate derivatives,and a comparison with ZDDP

Ashless substituted dithiophosphoric acid derivatives (ADPs) are a new generation of multifunctional additives with promising antiwear (AW) and extreme‐pressure (EP) characteristics. Three such additives synthesised in the authors' laboratory have been evaluated for their AW and EP properties by standard four‐ball friction and wear tests. The friction‐reducing properties of these additives were compared with those of a commercial zinc dialkyldithiophosphate (ZDDP). It was found that the phosphorodithioate compounds studied here possessed excellent AW/EP properties. Their AW characteristics were found to be comparable to those of ZDDP at low loads. However, at higher loads they show inferior AW characteristics in comparison to ZDDP. Nevertheless, ADP derived from cashew nut shell oil had a higher load‐carrying capacity than ZDDP. The mechanism of the AW and EP behaviour exhibited by the different additives was investigated using X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and scanning electron microscopy (SEM) of the worn surfaces formed during friction. XPS and AES analyses of the worn surfaces reveal that the tribochemical film formed on the ADP‐tested surfaces consisted mainly of metal phosphates and only a small amount of metal sulphides, even though the ADPs contained twice the number of sulphur atoms than phosphorus atoms. The ZDDP‐tested surface showed a mixture of metal sulphides and metal phosphates. Alkylamino substitution appeared to have no significant effect on the AW/EP properties of the additive. XPS and AES analyses also revealed that the tribochemical film formed on an ADP‐tested surface was thicker than that present on the ZDDP‐tested surface at low loads, whereas at higher loads the reverse was true. The higher weld load obtained for the blend containing cashew nut shell oil‐derived ADP is attributed to the thicker adsorbed reaction film formed on the surface due to the long alkyl groups present in the original additive structure. Short‐chain alkyl groups, however, form only a thin adsorbed layer, which may get rubbed off during the friction at high load. The low sulphide formation on ADP‐tested surfaces was attributed to the absence of any metal atom in the additive, which would help in the formation of metal sulphides during tribofragmentation and further tribochemical reactions.     

Determination of Calcium,Zinc, and Phosphorus in multigrade crankcase oils by XRF,DRES, and ICP-AES

The effect of viscosity index improvers such as styrene-isoprene copolymer (SICP), styrene-butadiene copolymer (SBCP), ethylene-propylene copolymer (OCP) and poly(alkyl) methacrylate (PMA), in multigrade oils on the determination of Ca, Zn and P in fresh and used lubricating oils was studied using XRF, DRES and ICP-AES techniques. Crankcase lubricating oil blends containing known amounts of Ca (2900 ppm), Zn (1700 ppm) and P (1600 ppm) were further formulated with different concentrations of these VI improvers and analysed for their Ca, Zn, and P contents by XRF, DRES and ICP-AES. Based on a comparison of the resulting analytical data, it was concluded that the VI improvers had no effect on the analysis results, and that the concentrations of Ca, Zn and P in the oil determined by these techniques correlate well with each other.     

Modification of Microstructure of Starch Extruded With Selected Lipids

Normal corn starch was extruded with palm, peanut and coconut oils; myristic, stearic and behenic acids and three monoglycerides in a C. W. Brabender single screw laboratory extruder at 140°C barrel temperature, 140rpm screw speed and 22% moisture content. Microstructure of extrudates was studied using a scanning electron mircocope. The pore size distribution, pore volumes and shear strengths of the extrudates were also studied. Addition of lipids resulted in modification of pore size distribution and pore volumes depending on the type of lipid. Complexing lipids gave lower pore volumes, smaller size pores, lower porosities and higher shear strengths of the extrudates. Porosity correlated well with the shear strength values.