Modeling of liquid hydrocarbon products from syngas

International Journal of Coal Science & Technology - The modeling of hydrocarbon selectivity and CO conversion of the Fischer–Tropsch synthesis over Fe–Ni/Al2O3 catalyst by using...     

A hierarchical stochastic modelling approach for reconstructing lung tumour geometry from 2D CT images

ABSTRACT

Lung cancer is one of the deadliest cancers in both men and women. Nowadays, several methods are used to cure this cancer including surgery and radiotherapy. These methods require prior knowledge about the shape of tumours. This type of knowledge may also help physicians to determine the cancer type. In this paper we propose a novel approach for 3D reconstruction of tumour geometry from a sequence of 2D images. The proposed approach consists of two phases: tumour segmentation from computed tomography (CT) images and 3D shape reconstruction. Segmentation is conducted using snake optimisation and Gustafson–Kessel clustering. For 3D reconstruction, first, we propose a new approach to interpolate some intermediate slices between original slices. Then, the well-known marching cubes algorithm is used for surface reconstruction. Eventually, we smoothen the surface using an explicit fairing algorithm. Experiments show that our new approach can highly improve the quality and the accuracy of the reconstructed tumour shape.     

Bi-supported Ziegler–Natta TiCl4/MCM-41/MgCl2 (ethoxide type) catalyst preparation and comprehensive investigations of produced polyethylene characteristics

Bi-supported Ziegler–Natta catalysts (TiCl₄/MCM-41/MgCl₂ (ethoxide type)) were synthesized to improve the morphology and the properties of polyethylene. The morphology control is a crucial issue in polymerization process, while tailoring the properties of polymers is needed for specific applications. The catalysts were synthesized in different ratios of two supports with impregnation method. The polymerization process was carried out in atmospheric slurry reactor. The catalysts were characterized with scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM–EDX), inductively coupled plasma, Fourier transform infrared spectrometry (FTIR), and Brunauer-Emmett-Teller (BET) methods. The polymers were analyzed with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry, FTIR, and tensile-strength analyses. Ubbelohde viscometer and frequency sweep measurements showed that the synthesized polymers are ultra-high-molecular-weight polyethylene. Mechanical properties of polymers showed higher Young's modulus in samples containing MCM-41, having higher thermal stability supported by TGA analysis. SEM images of bi-supported catalyst showed a controlled spherical morphology with uniform size distribution. SEM analysis support that the polymers replicate their morphology from catalyst, improving their morphology comparing to MgCl₂-supported catalyst. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48553.     

Principal component analysis-based predictive modeling and optimization of permanent deformation in asphalt pavement: elimination of correlated inputs and extrapolation in modeling

Structural and Multidisciplinary Optimization - Permanent deformation in asphalt pavement is a function of material properties, loading, environmental conditions, and structural design (e.g.,...     

Non-isothermal aging of a high-Zn-containing Al–Zn–Mg–Cu alloy: microstructure and mechanical properties

The non-isothermal aging behaviour of a newly developed Al–Zn–Mg–Cu alloy containing 17?wt-% Zn was investigated. Hardness and shear punch tests demonstrated that during non-isothermal aging, the mechanical properties of the alloy first increased and then decreased. The best properties were obtained in a sample which was non-isothermally aged upto 250°C with heating rate of 20°C?min^?1, due to the presence of η′/η (MgZn₂) phases. This was confirmed by differential scanning calorimetery. After homogenisation, residual eutectic phases remained at triple junctions or in a spherical form. During aging, these phases transformed into rodlike S (Al₂CuMg)-phase at 400°C, with sizes ranging from 50 to 250?nm. The precipitation sequence in this high-Zn alloy was similar to that for conventional Al–Zn–Mg–Cu alloys.     

Numerical modeling of an umbrella arch as a pre-support system in difficult geological conditions: a case study

In order to prevent the collapse of ceilings and walls of large tunnels, especially in difficult geological conditions, either a sequential excavation method (SEM) or ground reinforcing method, or a combination of both, can be utilized. The first part of the adit tunnel in northwestern Iran is being drilled in alluvium material with very weak geotechnical parameters. Despite applying an SEM in constructing this tunnel, analyzing the numerical modeling done using FLAC3D, as well as observations during drilling, indicate tunnel instability. To increase operational safety and to prevent collapse, a pre-support system was designed and implemented. The results of the numerical modeling accompanied by monitoring during operation, as well as the results of instrumentation, indicate the efficacy of this method for preventing collapse in alluvium material along the tunnel route. Modeling the behavior of the umbrella arch shows that the location of the maximum compressive force will change with a change in the tunnel arc location. Moreover, displacement, force and moment exerted on the pipes will change during drilling steps according to a certain pattern.     

Medical-grade ultra-high molecular weight polyethylene: past,current and future

Ultra-high molecular weight polyethylene is a semi-crystalline polymer (45–60%) with six decades of orthopaedic applications. This polymer has a high fracture toughness (30?kJ?m^?2) which comes from the molecular weight and the chain entanglements. Adverse alteration of the properties may lead to the part's pre-mature failure. This paper reviews the current manufacturing methods, and their effect on the properties of the polymer. The review also focused on the attempts of enhancing the polymer properties. The main cause of failure is implant loosing owing to the polymeric wear particles. Many manufacturers have attempted to enhance the wear and oxidation properties of the polymer, and the outcome of the new technologies is critically reviewed. Finally, the review explores the potential for future developments.

This review was submitted as part of the 2018 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged.     

Intelligent breast cancer recognition using particle swarm optimization and support vector machines

Breast cancer is the most common cancer among women, except for skin cancer, but early detection of breast cancer improves the chances of survivability. Data mining is widely used for this purpose. As technology develops, large number of breast tumour features are being collected. Using all these features for cancer recognition is expensive and time-consuming. Feature extraction is necessary for increasing the classification accuracy. The goal of this work is to recognise breast cancer using extracted features. To reach this goal, a combination of clustering and classification is used. Particle swarm optimization is used to recognise tumour patterns. The membership degree of each tumour to the patterns is calculated and considered as a new feature. Support vector machine is then employed to classify tumours. Finally this method is analysed in terms of its accuracy, specificity, sensitivity and CPU time consuming using Wisconsin Diagnostic Breast Cancer data set.     

Investigation of the effect of carbonaceous supports on the activity and stability of supported palladium catalysts for methanol electro-oxidation reaction

In this study, nitrogen doped graphene (NG) and multi-walled carbon nanotubes (MWCNT) were used as supporting materials for palladium active phase to investigate their performance in direct methanol fuel cells (DMFCs). The facile and low temperature solvothermal method was used for the synthesis of NG. Palladium nanoparticles were deposited on the surface of NG and MWCNT by a modified polyol reduction method. The morphologies and microstructures of the prepared catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Also, cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy were carried out to evaluate the electrocatalytic activity and the durability of the obtained catalysts towards methanol oxidation reaction. Pd/NG catalyst had a better activity and durability of methanol electrocatalytic oxidation rather than Pd/MWCNT catalyst, which is related to good dispersion of Pd nanoparticles on the surface of nitrogen doped graphene and the physicochemical characteristics of NG.     

Collaborative mechanisms for sustainability-oriented supply chain initiatives: state of the art,role assessment and research opportunities

Whether from government policies, customer expectations or personal beliefs, there is increasing pressure on firms and their supply chains to adopt sustainable practices. Manufacturing companies are particularly targeted, for example, to reduce CO₂ emissions, offer sustainable products, etc. Research in this field has significantly increased in recent years. Most research states the importance of collaboration with upstream and downstream entities as a critical success factor when aiming for a sustainable supply chain and proposes various collaborative mechanisms (CMs) to enable firms in the implementation of a sustainability-oriented initiative. The goal of this paper is to investigate the role of collaboration in these initiatives and explore the proposed CMs via a systematic literature review method. A total of 404 articles were reviewed and the multitude of CMs proposed in the literature were classified into seven categories: relationship management, contractual and economic practices, joint practices, technological and information sharing practices, governance practices, assessment practices, and supply chain design. This systematic mapping of the field provides an in-depth view of the current state of research as well as research gaps. It also intends to help practitioners by highlighting the role played by these mechanisms in four phases of sustainable supply chain deployment.