A GRASP Algorithm Based on New Randomized Heuristic for Vehicle Routing Problem

This paper presents a novel GRASP algorithm based on a new randomized heuristic for solving the capacitated vehicle routing problem, which characterized by using a fleet of homogenous vehicle capacity that will start from one depot, to serve a number of customers with demands that are less than the vehicle capacity. The proposed method is based on a new constructive heuristic and a simulated annealing procedure as an improvement phase. The new constructive heuristic uses four steps to generate feasible initial solutions, and the simulated annealing enhances these solutions found to reach the optimal one. We tested our algorithm on two sets of benchmark instances and the obtained results are very encouraging

Studies of the Solvent-Free Knoevenagel Condensation over Commercial NiO compared with NiO Drived from Hydrotalcites

In this study, we compared the effect of the commercial NiO, synthesis NiAl-HT and NiO-HT drived from hydrotalcite in Knoevenagel condensation reaction. The NiAl-HT sample was synthesized by the coprecipitation method with a molar ratio M2+/M3+ = 2 at constant basic pH. X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) were utilized to identify crystalline phases present in NiAl-HT, NiO-HT and commercial NiO. The chemical composition of the obtained solids was determined by Atomic Absorption Spectroscopy (AAS). Other techniques, such as Thermogravimetric Thermal Analyzer (TGA), Scanning Electron Microscopy (SEM) and Brunauere Emmette Teller Method (BET) were also used. As well as the BET showed the increase of the specific surface for the solid NiO-HT. The performance of the catalysts were studied in Knoevenagel condensation of benzaldehyde with ethyl acetoacetate without solvent to synthesis of organic compounds such as intermediates of dihydropyridines derivatives. The influence of different parameters, such as catalyst amount, reaction temperature and reaction time were optimized for studied the activity, the selectivity and the stability of the solids. Catalytic activity was in its lowest in the presence of NiAl-HT (26% of benzaldehyde conversion) whereas the benzaldehyde conversion increased to 77% in case of NiO-HT which can be explained by the presence of the basic sites of the NiO-HT oxides, a high surface area and a small crystallite size. Therefore, the lower increase in benzaldehyde conversion was noticed using commercial NiO (84%), perhaps owing to its high purity. A reaction mechanism is proposed by using density functional method (DFT). Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0

Methane seepage in a Cretaceous greenhouse world recorded by an unusual carbonate deposit from the Tarfaya Basin, Morocco

During the Cretaceous major episodes of oceanic anoxic conditions triggered large scale deposition of marine black shales rich in organic carbon. Several oceanic anoxic events (OAEs) have been documented including the Cenomanian to Turonian OAE 2, which is among the best studied examples to date. This study reports on a large limestone body that occurs within a black shale succession exposed in a coastal section of the Tarfaya Basin, Morocco. The black shales were deposited in the aftermath of OAE 2 in a shallow continental sea. To decipher the mode and causes of carbonate formation in black shales, a combination of element geochemistry, palaeontology, thin section petrography, carbon and oxygen stable isotope geochemistry and lipid biomarkers are used. The ¹³C-depleted biphytanic diacids reveal that the carbonate deposit resulted, at least in part, from microbially-mediated anaerobic oxidation of methane in the shallow subseafloor at a hydrocarbon seep. The lowest obtained δ¹³Ccarbonate values of −23.5‰ are not low enough to exclude other carbon sources than methane apart from admixed marine carbonate, indicating a potential contribution from in situ remineralization of organic matter contained in the black shales. Nannofossil and trace metal inventories of the black shales and the macrofaunal assemblage of the carbonate body reveal that environmental conditions became less reducing during the deposition of the background shales that enclose the carbonate body, but the palaeoenvironment was overall mostly characterized by high productivity and episodically euxinic bottom waters. This study reconstructs the evolution of a hydrocarbon seep that was situated within a shallow continental sea in the aftermath of OAE 2, and sheds light on how these environmental factors influenced carbonate formation and the ecology at the seep site

A comprehensive review of swarm optimization algorithms

Many swarm optimization algorithms have been introduced since the early 60’s, Evolutionary Programming to the most recent, Grey Wolf Optimization. All of these algorithms have demonstrated their potential to solve many optimization problems. This paper provides an in-depth survey of well-known optimization algorithms. Selected algorithms are briefly explained, and compared with each other comprehensively through experiments conducted using thirty well-known benchmark functions. Their advantages and disadvantages are also discussed. A number of statistical tests are then carried out to determine the significant performances. The results indicate the overall advantage of Differential Evolution (DE) and is closely followed by Particle Swarm Optimization (PSO), compared with other considered approaches