Genetic algorithm based approaches to solve the order batching problem and a case study in a distribution center

Journal of Intelligent Manufacturing - The order batching problem is a combinatorial optimization problem that arises in the warehouse order picking process. In the order batching problem, the aim...     

Identification of the continuum damage parameter: An experimental challenge in modeling damage evolution

To accurately predict ductile failures of new advanced metals, continuum damage models (CDMs) require experimental determination of material-specific damage parameter(s). While various experimental techniques are being used to determine these damage parameter(s), possible systematic errors due to methodological differences in damage definition have yet to be fully revealed. With the aim of finding the most reliable ductile damage quantification strategy for CDMs, this work provides an in-depth comparison of six theoretically equivalent methodologies by considering measurement accuracy, precision, damage spectrum, spatial resolution and practicality. It is found that the methodologies that quantify ductile damage from its geometry introduce significant systematic errors as they probe a very limited damage spectrum, whereas the methodologies that probe the degradation of a mechanical property suffer from low precision and high complexity, especially for high strains and material anisotropy.     

A critical assessment of indentation-based ductile damage quantification

This paper scrutinizes the reliability of indentation-based damage quantification, frequently used by many industrial and academic researchers. In this methodology, damage evolution parameters for continuum damage models are experimentally measured by probing the deformation-induced degradation of either hardness or indentation modulus. In this critical assessment the damage evolution in different sheet metals was investigated using this indentation approach, whereby the obtained results were verified by other experimental techniques (scanning electron microscopy, X-ray microtomography and highly sensitive density measurements), and by finite element simulations. This extensive experimental–numerical assessment reveals that the damage-induced degradation of both hardness and modulus is at least partially, but most likely completely, masked by other deformation-induced microstructural mechanisms (e.g. grain shape change, strain hardening, texture development, residual stresses and indentation pile-up). It is therefore concluded that hardness-based or modulus-based damage quantification methods are intrinsically flawed and should not be used for the determination of a damage parameter.     

Novel Heterobimetallic Radiotheranostic: Preparation,Activity, and Biodistribution

A novel Ru^II(arene) theranostic complex is presented. It is based on a 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid macrocycle bearing a triarylphosphine and can be tracked in vivo by using the γ emission of ¹⁵³Sm atoms. Notably, the heteroditopic ligand can be selectively metalated with ruthenium at the phosphorus atom despite the presence of other functionalities that are prone to metal coordination. Subsequent labeling with radionuclides such as ¹⁵³Sm can then be performed easily. The resulting heterobimetallic complex exhibits favorable solubility and stability properties in biologically relevant media. It also shows in vitro cytotoxicity in line with that expected for this type of metallodrug, and is nontoxic to the organism as a whole. As a proof of concept, initial studies in healthy mice were performed to obtain information about the uptake, biodistribution, and excretion of the radiolabeled complex.     

Recent progress in microstructural hydrogen mapping in steels: quantification,kinetic analysis,and multi-scale characterisation

ABSTRACT

This paper gives an overview of recent progress in microstructure-specific hydrogen mapping techniques. The challenging nature of mapping hydrogen with high spatial resolution, i.e. at the scale of finest microstructural features, led to the development of various methodologies: thermal desorption spectrometry, silver decoration, the hydrogen microprint technique, secondary ion mass spectroscopy, atom probe tomography, neutron radiography, and the scanning Kelvin probe. These techniques have different characteristics regarding spatial and temporal resolution associated with microstructure-sensitive hydrogen detection. Employing these techniques in a site-specific manner together with other microstructure probing methods enables multi-scale, quantitative, three-dimensional, high spatial, and kinetic resolution hydrogen mapping, depending on the specific multi-probe approaches used. Here, we present a brief overview of the specific characteristics of each method and the progress resulting from their combined application to the field of hydrogen embrittlement.

This paper is part of a thematic issue on Hydrogen in Metallic Alloys     

Mechanical performance of resol type phenolic resin/layered silicate nanocomposites

Clay addition has been shown to affect polymer resins positively in terms of several physical and chemical properties, including mechanical performance, high temperature endurance and durability. These increases are limited only to relatively low concentrations of reinforcement phase, but at these low concentrations polymer/layered silicate nanocomposites (P/LS NC) have shown to exhibit higher mechanical performance than fiber reinforced polymer composites. This is among the several reasons that make P/LS NC's one of the most widely studied class of materials today. In this study, the mechanical performance of resol type phenolic resin/layered silicate nanocomposite specimens was examined by carrying out 3‐point bending, Charpy impact and fracture toughness tests to couple the observations, microstructural analysis is done through X‐ray diffraction and scanning electron microscopy. The effects of especially three factors; cure method, clay amount, and clay modification were investigated. It was concluded that highest mechanical performance was obtained by the acid curing of the phenolic resin with very low amounts (e.g., 0.5%) of either very hydrophobic or very hydrophilic Na‐montmorillonite clay additions. Improvements as high as 7% in flexural strength, 11% in flexural strain at break, 16% in Charpy impact strength, and 66% in fracture toughness values were obtained. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Reduced energy consumption by using streamlined gating systems

In foundries a lot of effort is done to minimize energy consumption in the production to reduce costs and hence increase the competitiveness. At the same time the foundries must live up to the increased demands for high quality castings. Traditional gating systems are known for a straight tapered down runner, a well base and 90° bends in the runner system. Previous work has shown that the traditional way of designing gating systems creates high inconsistency in flow patterns during filling. In the streamlined gating systems there are no sharp changes in direction and a large effort is done to confine and control the flow of the molten metal during mould filling. The main objective in the work presented here is to use the principles of the streamlined gating systems to reduce the weight of the gating system relative to the traditional layouts. By reducing the weight of gating system and thereby improving yield, the amount of molten iron needed is also reduced, hence reducing the energy consumption for melting. Experiments in real production lines have proven that it is possible to achieve a reduction in the poured weight by using the streamlined gating systems. In a layout for casting of three valve housings in a vertically parted mould the weight of the gating system was reduced by 1.1 kg changing from the traditional layouts to the streamlined gating systems. This weight reduction corresponds in this case to a 20% weight reduction for the gating system. Using streamlined gating systems with fan gates to give a beneficial heat distribution in the castings may be an efficient tool to eliminate the need for heat treatment. In the experiments the change in gating system from the traditional layout to the streamlined layout removed the need for heat treatment. This obviously means a huge energy saving in the foundry. The energy consumption for heat treatment of iron has been found to be 0.489 kWh/ kg. The valve housing in the experiments weighs 3 kg so when the need for heat treatment is removed, around 1.5 kWh     

Refining the outer camera orientation in synchronized shooting from two spacecrafts

Methods for simultaneous refining the outer orientation parameters of satellite cameras in synchronized shooting from two spacecrafts moving in the same orbit are proposed and investigated. The methods are based on taking into account perspective relations between corresponding coordinates of projections of region elements in a synchronized series of stereograms under assumption that the common aiming point of the cameras does not change during shooting. A method for space shooting simulation is described and used for investigating the dependences of the errors of estimating the orientation angles of the cameras on the number of stereograms and the noise level in projective coordinates of region element images.     

Determination of FA composition and total trans FA of Turkish margarines by capillary GLC

In this research, FA composition and total trans FA contents of 16 different brands of margarine (8 hard-type and 8 soft-type) sold in Turkey were determined by capillary GLC method. According to the results, the contents of saturated FA, monounsaturated FA, and PUFA were within the ranges of 23.9–32.3, 44.0–61.9, and 14.2–24.1%, respectively, in hard-type margarines, and 27.0–39.9, 21.0–40.9, and 32.0–53.7%, respectively, in soft-type margarines. Hard-type margarines contained total trans FA concentrations of 20.1–34.3%, whereas soft-type margarines contained less than 8.9% total trans FA. C_18∶1 trans acid content was within the range of 18.5–29.8% in hard-type margarines, and it was significantly higher than the range in soft margarines (0.7–8.1%). C_18∶1 trans acid was the major trans FA in all margarines, and C_18∶3 trans acid concentrations were less than 0.2%.