A detailed insight into the optimization of plate and frame heat exchanger design by comparing old and new generation metaheuristics algorithms

The voluminous utilization and application of plate and frame heat exchangers (PFHE) in many industries has accelerated the consumer and designer both to optimize exchanger total cost. Over the last few years, several old and new generation algorithms were employed and exploited to optimize PFHE cost. This study explores the application and performance of three new-generation algorithms Big Bang-Big Crunch (BBBC), Grey Wolf Optimizer (GWO), and Water Evaporation Optimization (WEO) in designing optimally PFHE. Besides, this study also compares the performance of three well-established old generations algorithms namely genetic algorithm (genetics and natural selection), particle swarm optimization (animals behaviour), and differential evolution (population-based) with the above three new algorithms in the optimization of PFHE.Seven design factors are chosen for PFHE optimization: exchanger length on hot and cold sides, height and thickness of fin, length of the fin-strip, fin frequency, and the number of hot side layers. The applicability of the suggested algorithms is assessed using a case study based on published research. Though DE performs the best in this study of design optimization concerning total cost and computational time, the three new-generation meta-heuristic algorithms BBBC, GWO, and WEO also provide the novel scope of application in heat exchanger design optimization and successfully finding the cost of the heat exchanger. According to this study, capital costs increase by 19.5% for BBBC, 24% for GWO, and 7.6% for GWO, but operational costs fall by 9.5% for BBBC and GWO when compared to the best performing algorithm (DE). On the other hand, WEO shows an increase of 32.6% in operational costs. Aside from that, a full analysis of the computing time for each algorithm is also provided. The DE has the quickest run time of 0.09 ?s, while the PSO takes the longest at 33.97 ?s. The rest of the algorithms have nearly identical values. As a result, a good comparison is established in this study, offering an excellent platform for designers and customers to make selections. Additionally, the three new generations algorithms mentioned here were not used earlier for optimization of PFHE and the comparative study illustrates that each of them possesses eat potential for cost optimization and also solving other complex problems.     

Vertical distribution and radiological risk assessment of natural radionuclides in the alluvial soil profile of south-west Punjab,India

Journal of Radioanalytical and Nuclear Chemistry - Natural radionuclide levels are studied in alluvial sediments upto the depth of 900 cm. Eighteen profiles are selected from agricultural...     

A Convenient Route To 1,2-Dibenzoyl-1-Arylethylenes

Short and convenient syntheses of 1,2-cis-dibenzoyl-1-ary 1-ethylenes 5a-e, 6 and 8a-d from the corresponding aryl ethers and dibenzoyl acetylene have been developed using boron trifluoride-etherate or aluminium chloride as catalyst.     

Method for detection of single-base mismatches using bimolecular beacons

This paper describes a method for the detection of single-base mismatches using DNA microarrays in a format that does not require labeling of the sample ("target") DNA. The method is based on disrupting fluorescence energy transfer (FRET) between a fluorophore attached to an immobilized DNA strand ("probe") and a quencher-containing sequence that is complementary except for an artificial mismatch (e.g. 5-nitroindole, 3-nitropyrole, or abasic site) at the site of interrogation. As the displacement of the FRET acceptor and hybridization of the unlabeled probe are bimolecular, the term "bimolecular beacons" is used to describe this approach. The analysis of a mismatch was based on differences in the amount of disruption in FRET upon hybridization of perfectly matched DNA targets and those containing single-base mismatches. Using this method and an oligonucleotide model system, A/C single-base mismatches were successfully discriminated at levels greater than that observed using surface-immobilized molecular beacons. The amount of discrimination was dependent on the identity of the artificial mismatch; greater discrimination was observed with 5-nitroindole (a "universal" base) than with an abasic site. G/T mismatches, considered to be particularly difficult to detect, were also successfully discriminated when quencher sequences containing 5-nitroindole were used.     

Chemically assisted ion beam etching of silicon and silicon dioxide using SF6

A chemical flux of sulfur hexafluoride (SF₆) in conjunction with low-energy Ar-ion bombardment has been used for chemically assisted ion beam etching (CAIBE) of silicon and silicon dioxide. The study has shown a large degree of independent control over the selectivity and anisotropy in dry etching. The total etch rate could be controlled by varying either the Ar-ion milling parameters or the chemical flux of SF₆. Etch rate enhancement of 7–8 for silicon and 3–4 for silicon dioxide have been obtained over pure physical etching.     

Determination of the Association Constants of Charge-Transfer Complexes Between N,N-Diethylaniline and Nitro Explosives Using High Performance Thin Layer Chromatography with Scanning Video Densitometry and Spectrophotometry

Charge-transfer (CT) or electron donor-acceptor (EDA) complex formation between organic donors and acceptors has been extensively studied by spectrophotometry and other methods. High performance thin layer chromatography (HPTLC), although extensively used for the identification and quantification of drugs and explosives, has not been used until now to determine the extent of association and the association constants K _DA of charge transfer or EDA complexes between donor (D) and acceptor (A). This paper describes the use of the HPTLC technique with scanning densitometry to identify and determine the association constants K _DA of charge-transfer complexes of N,N-diethylaniline (DEA) with different nitro explosives, namely 1,4-dinitrobenzene (DNB), 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT), in chloroform. Advantages of the HPTLC method are highlighted. The association constants K _DA of the complexes determined using the HPTLC method have been verified and validated spectrophotometrically when the concentrations of D and A are in their stoichiometric ratio. The thermodynamics of the complex formation reaction were obtained spectrophotometrically from measurements of the association constants K _DA at five different temperatures ranging from 293 to 313 K, when D and A are in their stoichiometric ratio and also when A≫D.     

Separation of no-carrier-added Tl and Pb radionuclides using poly(N-vinylpyrrolidone)

No-carrier-added (nca) ^199–201Tl has been separated from nca ^199–201Pb using an environmentally friendly biocompatible polymer, poly(N-vinylpyrrolidone). The method uses no harmful chemicals and is based on the process of dialysis of PVP-Pb and PVP-Tl complexes against triple-distilled water. It has been observed after one hour of dialysis that 75–85% Tl (in both +3 and +1 oxidation states) comes out of dialysis sack without any contamination from lead.     

Valence-state analysis through spectroelectrochemistry in a series of quinonoid-bridged diruthenium complexes [(acac)(2)Ru(mu-L)Ru(acac)(2)](n) (n=+2, +1, 0, -1, -2)

The quinonoid ligand-bridged diruthenium compounds [(acac)(2)Ru(mu-L(2-))Ru(acac)(2)] (acac(-)=acetylacetonato=2,4-pentanedionato; L(2-)=2,5-dioxido-1,4-benzoquinone, 1; 3,6-dichloro-2,5-dioxido-1,4-benzoquinone, 2; 5,8-dioxido-1,4-naphthoquinone, 3; 2,3-dichloro-5,8-dioxido-1,4-naphthoquinone, 4; 1,5-dioxido-9,10-anthraquinone, 5; and 1,5-diimido-9,10-anthraquinone, 6) were prepared and characterized analytically. The crystal structure analysis of 5 in the rac configuration reveals two tris(2,4-pentanedionato)ruthenium moieties with an extended anthracenedione-derived bis(ketoenolate) pi-conjugated bridging ligand. The weakly antiferromagnetically coupled {Ru(III)(mu-L(2-))Ru(III)} configuration in 1-6 exhibits complicated overall magnetic and EPR responses. The simultaneous presence of highly redox-active quinonoid-bridging ligands and of two ruthenium centers capable of adopting the oxidation states +2, +3, and +4 creates a large variety of possible oxidation state combinations. Accordingly, the complexes 1-6 exhibit two reversible one-electron oxidation steps and at least two reversible reduction processes. Shifts to positive potentials were observed on introduction of Cl substituents (1-->2, 3-->4) or through replacement of NH by O (6-->5). The ligand-to-metal charge transfer (LMCT) absorptions in the visible region of the neutral molecules become more intense and shifted to lower energies on stepwise reduction with two electrons. On oxidation, the para-substituted systems 1-4 exhibit monocation intermediates with intervalence charge transfer (IVCT) transitions of Ru(III)Ru(IV) mixed-valent species. In contrast, the differently substituted systems 5 and 6 show no such near infrared (NIR) absorption. While the first reduction steps are thus assigned to largely ligand-centered processes, the oxidation appears to involve metal-ligand delocalized molecular orbitals with variable degrees of mixing.     

Probing photochemical transformations at TiO2Pt and TiO2Ir interfaces using x-ray absorption spectroscopy

Structural transformations at the TiO2Pt and TiO2Ir interfaces during UV-irradiation have been probed by X-ray absorption spectroscopy. Oxidation by the photogenerated holes results in the intercalation of Pt and Ir into the Titania matrix. The structural transformations observed with Pt and Ir nanoparticles anchored on TiO2 is different than the clustering of gold atoms observed in the TiO2/Au system. Implications of such structural transformations on the photocatalytic activity of semiconductor photocatalyts are discussed.