160 research outputs found
Assessment of soil quality indices in agricultural lands of Qazvin Province, Iran
No full textSoil quality evaluation is a tool to improve soil management and land use system. A large number of different physical, chemical and biological properties of soil, known as soil quality indicators, are used to soil quality assessment. These properties, that are sensitive to stress or disturbance, are synthesized using numerical quality indices obtained by several different types of methods. The aim of this study was to compare two different methods for soil quality index calculation in agricultural lands of Qazvin Province, Iran. In particular, the Integrated Quality Index (IQI) and Nemoro Quality Index (NQI) models were applied using the indicator selection methods: Total Data Set (TDS) and Minimum Data Set (MDS). Ten soil quality indicators were included in TDS: pH, Electrical Conductivity (EC), Organic Matter (OM), Cation Exchange Capacity (CEC), percentage of equivalent CaCO3 (TNV), heavy metal content of cadmium (Cd), cobalt (Co), lead (Pb), chromium (Cr) and soil erodibility factor (K), while Principal Components Analysis (PCA) was used to select the indicators to include in MDS. The tested soil quality indices were appropriate to evaluate the effects of land management practices on soil quality. The results of the linear relationship as well as of the match analysis, among the approaches studied, identified better estimation of soil quality applying IQI index when compared to NQI index and higher values of agreement of TSD than MSD. However, also IQIMSD approach resulted in suitable evaluation of the effects of land management practices on soil quality. This latter result was particularly relevant in the area studied because the use of a limited number of indicators could allow to reduce the cost of the analysis and to increase the sampling density in order to obtain a more detailed evaluation of soil quality through a geostatistical approach. © 2013 Elsevier Ltd. All rights reserved
Ultralight Membrane Structures Toward a Sustainable Environment
No full textThe building construction industry is the largest anthropogenic source of pollution, with massive energy consumption and substantial CO2 emissions. Lightweight tension structures allow the simultaneous implementation of several sustainable strategies by using recyclable low-carbon structural membranes offering a greener alternative to glass and other cladding materials. Their efficient structural load-bearing mechanisms result in significant weight savings in buildings and a drastic reduction of the environmental impact associated with material production, transportation, use, and disposal. A subgroup of lightweight materials, structural fabrics, and foils has been gaining popularity among designers and architects in recent years because of their desirable features such as high stiffness, strength, ductility, durability, and functional properties. While these structural membranes open new crucial perspectives for the clean energy transition and have been recently employed worldwide, their full potential is still limited by the lack of construction codes, advanced optimization tools, and comprehensive viscous-thermo-mechanical constitutive models. This chapter aims to foster the design of membrane structures by presenting their basic principles and recent advancements in the field. It covers the design approaches, employed materials and efforts in their characterization and modeling, implications on the sustainability of the built environment, current challenges, and future pathways from both academic research and engineering design viewpoints.Team Marcel Sluite
The Elderly Mental Health in the Holy Quran
No full textObjectives: The present research aimes to discuss the mental healthof elders in the Holy Quran and Hadiths.
Methods & Materials: The study uses the method of content and library analysis in which the Holy Quran and its commentaries have been studied by using a Quranic software and Hadith books and softwares. The data has been collected and classified according tothe topics.
Results: Results of the research included the definition of the elderly in view of Islam, introduction of elders, and their rights and status in Islam, Islamic treatment of elders and old parents, kindness and methods of kindness and goodness, virtuous and suitable behavior, good verbal and humble behavior, frequent visit, subsistence, prayers and thankfulness.
Conclusion: According to the results concluded form the Holy Quran and Hadiths, the mental health of the elderly peopel has beenconsidered in the following three aspects: The elders in the public’s point of view The elders in the government’s point of viewThe elders and their parental role
Community detection in complex networks, 2015
No full textThis research study has produced advances in the understanding of communities within a complex network. A community in this context is defined as a subgraph with a higher internal density and a lower crossing density with respect to other subgraphs. In this study, a novel and efficient distance-based ranking algorithm called the Correlation Density Rank (CDR) has been proposed and is utilized for a broad range of applications, such as deriving the community structure and the evolution graph of the organizational structure from a dynamic social network, extracting common members between overlapped communities, performance-based comparison between different service providers in a wireless network, and finding optimal reliability-oriented assignment tasks to processors in heterogeneous distributed computing systems. The experiments, conducted on both synthetic and real datasets, demonstrate the feasibility and applicability of the framework
Religious Orientation (Internal and External) Effects on Aged Mental Health
No full textObjective: The purpose of present study is to investigate "religious orientation (internal and external) effects on aged mental health".
Materials & Methods: In an expost-facto and correlational study 230 male and female residents of elderly centers affiliated to welfare organization and public places (such as mosques and park) in which the non–resident aged persons gather, were selected through clustered randomized sampling. َAt first, the subjects were screened from cognitive disorders. Then, they completed GHQ-28, Beck Depression Inventory and Religious Attitude Test. The data were analysed through Pearson correlatioal Test and Mann-Whitney.
Results: The results revealed that there is a significant correlation between elder depression and mental health. In the other words, the higher scores on external religious orientation, the higher scores on mental health problems and rates of depression. The more trends toward internal religious orientation, the lower rate of depression and mental health problems. Also, there was a meaningfull correlation between elder religious orientation and their mental health and depression rate. In other words, there was a meaningful correlation between mental health and depression rate of resident and non- resident elders. In addition women had more external religious orientation, while men had higher rates of internal religious orientation.
Conclusion: External religious belief had meaningful correlation with mental disorders and depression, and internal religious belief had meaningful correlation with mental health. Mental disorders and depression are more prevalent among resident elder than the non-residents, and also the resident elders have more external religious orientation
Modeling of Precipitation Sequence and Ageing Kinetics in Al-Mg-Si Alloys
No full textAl-Mg-Si alloys are heat treatable alloys in which strength is obtained by precipitation hardening. Precipitates, formed from a supersaturated solid solution during ageing heat treatment, are GP-zones, B", B´ and B-Mg2Si. Precipitation kinetics and strength vary with alloy composition and process parameters. There is still a need for property and process optimization and therefore to investigate precipitation in this system. Therefore, the general objective is to develop process models to study precipitation kinetics and precipitation sequence in Al-Mg-Si alloys. Precipitates in Al-Mg-Si alloys usually nucleate with a spherical morphology but grow with an elongated shape. An age-hardening model is used to study the effects of morphology of precipitate on the strengthening of Al-Mg-Si alloys (Chapter 2). The results show that age-hardening models, assuming elongated precipitates of constant aspect ratio, do not give an overall better prediction of precipitation and strength evolution during ageing and the assumption of spherical precipitates remains, as a first approximation, an acceptable assumption. The Kampmann-Wagner numerical (KWN) framework, as a base ageing model, is introduced in chapter 3. The KWN model is a method for modelling coupled nucleation, growth, and coarsening. In this method, the precipitate size distribution is simulated using a finite difference method. Current precipitation models, applied to aluminium alloys, usually assume that thermodynamic equilibrium is always fulfilled at the precipitate-matrix interface. This implies the assumption of an infinite interface mobility, which means very fast transformation of matrix to precipitate as soon as the local equilibrium is disturbed by diffusion. The validity of this assumption has been investigated in chapter 4. A modified version of KWN model is introduced in which a mixed-mode growth model has been implemented instead of the only diffusion-controlled growth equation. Using this model a comprehensive systematic study has been done on the effects of diffusivity, and type of precipitate, i.e. interface energy and mobility, on the kinetics and character of precipitation in Al-Mg-Si alloys. The results show that changes in the interfacial energy have almost no effect on the precipitation character. However, changes in diffusivity and interface mobility have significant influence on the character of precipitation. For example, it is shown that there is a certain radius below which precipitation character is always interface controlled. In chapter 5, the complexity of the precipitation sequence and its effect on the precipitation kinetics during ageing has been investigated with a multi-component multi-precipitate model, based on the assumption of maximum Gibbs free energy dissipation. In this modelling framework it is possible to consider simultaneous formation of GP-zones, B'', B', B, and free-Si. The model predicts that a large fraction of nuclei of different precipitate species form during quenching from solutionizing temperature and during heating to ageing temperature. Nucleation is first followed by the growth of the less stable species, which dissolve at some point in favor of more stable precipitates. In the end, only thermodynamically stable precipitates like b and free-Si remain in the alloy. The model also confirms that maximum strength is reached when B'' is the dominant precipitate. The effects of secondary precipitates, induced by interrupted ageing, on the age hardening of Al-Mg-Si alloys have been presented in chapter 6. In the interrupted ageing the alloy is first aged at an elevated temperature (e.g. 170 °C), quenched and then exposed to a lower temperature (e.g. 25-100 °C), and aged again at elevated temperatures. From the results it appears that the influence of secondary precipitates is highly dependent on the interruption temperature. Secondary precipitation stimulated by interruption at temperatures below 50 °C has almost no influence on the alloy strength, while when the interruption temperature is above 50 °C, it increases the hardness significantly. The proposed scenario to explain this behavior is based on the temperature-dependent competitive growth of GP-I and GP-II precipitates. According to this model, interruption temperature below 50 °C stimulates the formation of GP-I zones, which have a very slow kinetics of transformation and therefore they have almost no influence on the mechanical properties. On the other hand, when the alloy is interrupted at temperatures above 50 °C, the formation of GP-II zones is more likely to take place, consequently resulting in the higher density of ?" precipitates during re-ageing and better mechanical properties. Previous precipitation models were linked to a strength model to predict the yield strength evolution during ageing. However, the whole work-hardening behavior is also important for many applications of Al-Mg-Si alloys. In the last chapter, the influence of ageing on work-hardening is investigated from tensile tests. A modified version of Kocks-Mecking-Estrin (KME) model is then employed to simulate the work-hardening response as a function of the precipitation state. Results reveal that underaged material shows a linear decrease of the work-hardening rate with flow stress, while overaged material shows an initial constant work-hardening rate before decreasing linearly. This distinct behavior has been related to the stability of the Orowan loops. In conclusion, the thesis addresses several important issues concerning precipitation and work-hardening behavior of Al-Mg-Si alloys, including precipitates morphology, precipitation sequence, precipitation character, and interrupted ageing. This allows for a better understanding of precipitation sequence, precipitation and hardening kinetics in these alloys. The results of this study can be used for optimization of both chemical composition and ageing parameters in order to achieve desirable microstructure and mechanical properties.Materials Science and EngineeringMechanical, Maritime and Materials Engineerin
Application of waste ceramic powder as a cement replacement in reinforced concrete beams toward sustainable usage in construction
No full textThis article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). The paper is retracted at the request of the Editor-in-Chief. The Editors no longer have confidence in this paper. Following a complaint received by the editors, it was found upon investigation that 5 citations were added to this paper at the author proof stage. In most cases the added citations were not immediately relevant to the paper topic and in some cases, the added citations appear to benefit co-corresponding authors and a few other related individuals. This is an instance of citation farming (or citation dumping) and is a violation of publication ethics standards. Corresponding author Özkılıç acknowledges adding the citations but disagrees with the retractions. Corresponding author Bahrami disagrees with these retractions. The journal apologises for not identifying this breach during production. © 2024 The AuthorsNajran University, NU; Ministry of Education - Kingdom of Saudi Arabia, MoE, (NU/IFC/2/SERC/-/24); Ministry of Education - Kingdom of Saudi Arabia, Mo
Reliability and Factorial Structure of the Farsi Version of the Arabic Scale of Death Anxiety in an Iranian Middle-Aged Sample
No full textThe present study aimed to explore the psychometric properties of the Arabic Scale of Death Anxiety (ASDA) in an Iranian middle-aged sample. A sample of 55 volunteer Iranian persons took part in the study. Cronbach’s alpha of the ASDA was found to be high (0.91) and Spearman-Brown and Guttman Split-Half coefficients were 0.86. The factor analysis of the ASDA items yielded five factors accounting for 72.49% of the total variance and labeled (F1) fear of death and fear of dead people; (F2) fear of postmortem events and fear of tombs; (F3) fear of lethal disease; (F4) preoccupation with after death, and death fear in sleep; and (F5) fear of deprivation of own ones. The ASDA has a good validity and reliability, and it can be used in clinical, educational, and research settings
Metastable Kitaev Magnets
No full textNearly two decades ago, Alexei Kitaev proposed a model for spin-1/2 particles with bond-directional interactions on a two-dimensional honeycomb lattice which had the potential to host a quantum spin-liquid ground state. This work initiated numerous investigations to design and synthesize materials that would physically realize the Kitaev Hamiltonian. The first generation of such materials, such as Na2IrO3, α-Li2IrO3, and α-RuCl3, revealed the presence of non-Kitaev interactions such as the Heisenberg and off-diagonal exchange. Both physical pressure and chemical doping were used to tune the relative strength of the Kitaev and competing interactions; however, little progress was made towards achieving a purely Kitaev system. Here, we review the recent breakthrough in modifying Kitaev magnets via topochemical methods that has led to the second generation of Kitaev materials. We show how structural modifications due to the topotactic exchange reactions can alter the magnetic interactions in favor of a quantum spin-liquid phase
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