18 research outputs found
Pressure-dependent weighted-sum-of-gray-gases models for heterogeneous CO2-H2O mixtures at sub- and super-atmospheric pressure
No full textThe effect of total pressure of gas mixture is included in the development of new coefficients for the weighted-sum-of-gray-gases model (WSGG). The WSGG formulation previously reported by Bordbar et al. (combustion and Flame 2014, V. 161, pp. 2435-2445), which accounts for variations of molar fraction ratio of H2O to CO2, was employed here to obtain a new total pressure-dependent WSGG model. Hence, the new model includes both the effect of total pressure and variation of molar fraction ratio. High-resolution absorption spectra of gases produced by line-by-line (LBL) calculations using the HITEMP2010 spectral database are used to produce the total emissivity databases needed for the WSGG model development and also to produce the benchmark solution of one-dimensional slab problems used for validation of the new model. The performance of the new WSGG model is studied through several test cases representing various conditions of total pressure, inhomogeneity of temperature, concentration of gas species and molar fraction ratios. In all cases, the new model exhibits a good agreement with the LBL solutions. The new WSGG coefficients allow the model to efficiently solve the spectral thermal radiation in both sub- and super-atmospheric combustion systems. (C) 2021 The Author(s). Published by Elsevier Ltd.Peer reviewe
Again on the So-Called Temple of the Fratarakās, Persepolis: An Image-Shrine From the Early Hellenistic Age
No full textThe author, who has been investigating the post-Achaemenid period in
the region of Fars since 2002, illustrates his important archival
“rediscovery” of Ernst Herzfeld’s sketchbook containing observations on
what he calls “Frātadāra Temple,” which is preserved in Washington
(USA), available online since 2019 thanks to a project by the
Smithsonian Institution.
This sketchbook partially makes up for the lack of an excavation report
on this site, which Herzfeld never published, to clarify a fundamental
point, namely the exact location of the five Greek inscriptions, which
also remained practically unpublished until 2012, except for their brief
mention in Herzfeld’s overviews.
Since the author’s previous publication in French on the monument had
not a wide audience in Iran, he also re-proposes with particular interest
for Iranian readers his interpretations of what he considers to be one of
the best documented temples for statues of the pre-Sasanian Iranian
world and completes them with a discussion of the implications of
this new information
Evaluation of CAMP-Like Effect, Biofilm Formation, and Discrimination of<i>Candida africana</i>from Vaginal<i>Candida albicans</i>Species
Get PDFCandida africana asa species recovered from female genital specimens is highly close toC. albicans. The present study was conducted to discriminateC. africanafrom presumptive vaginalC. albicansstrains by molecular assay and evaluate their hemolysin activity, biofilm formation, and cohemolytic effect (CAMP) with vaginal bacterial flora. A total of 110 stock vaginalC. albicansisolates were examined byHWP1gene amplification. Hemolysin activity and the ability of biofilm formation were evaluated by blood plate assay and visual detection methods, respectively.Staphylococcus aureus,Staphylococcus epidermidis, andStreptococcus agalactiaewere used to evaluate the CAMP-like effects in Sabouraud blood agar media. Based on the size of the amplicons (941 bp), all isolates were identified asC. albicans. All samples were able to produce beta-hemolysin. Moreover, 69 out of 110 of the isolates (62.7%) were biofilm-positive, 54 out of 110Candidaisolates (49%) demonstrated cohemolytic effects withS. agalactiae, and 48 out of 110 showed this effect withS. aureus(43.6%). All isolates were CAMP-negative withS. epidermidis. We detected all isolates asCandida albicansand almost half of the isolates were CAMP-positive withS. aureusandS. agalactiae, suggesting that these bacteria increase the pathogenicity ofCandidain vaginal candidiasis.</jats:p
Electrochemical and biological characterization of Ti–Nb–Zr–Si alloy for orthopedic applications
Get PDF| openaire: EC/H2020/860462/EU//PREMUROSA Funding Information: Financial supports of the European Commission under FP6 SME integrated project “Meddelcoat” (contract 026501-2) and from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie ITN “Premurosa” (GA 860462) are gratefully acknowledged. Authors are greatly thankful for the late Dr. A. V. Mazur for help in TNZS alloy preparation, Dr. H. Yu for assistance in thermodynamic database optimization and Dr. D. Sukhomlinov for his help in performing the SEM/EDS. The LEMI assistance in analyzing details for the cells-materials interactions, led by Mrs. Prof. M.-F. Harmand and Mrs. D. Pierron, is also gratefully acknowledged. Publisher Copyright: © 2023, The Author(s).The performance of current biomedical titanium alloys is limited by inflammatory and severe inflammatory conditions after implantation. In this study, a novel Ti–Nb–Zr–Si (TNZS) alloy was developed and compared with commercially pure titanium, and Ti–6Al–4V alloy. Electrochemical parameters of specimens were monitored during 1 h and 12 h immersion in phosphate buffered saline (PBS) as a normal, PBS/hydrogen peroxide (H2O2) as an inflammatory, and PBS/H2O2/albumin/lactate as a severe inflammatory media. The results showed an effect of the H2O2 in inflammatory condition and the synergistic behavior of H2O2, albumin, and lactate in severe inflammatory condition towards decreasing the corrosion resistance of titanium biomaterials. Electrochemical tests revealed a superior corrosion resistance of the TNZS in all conditions due to the presence of silicide phases. The developed TNZS was tested for subsequent cell culture investigation to understand its biocompatibility nature. It exhibited favorable cell-materials interactions in vitro compared with Ti–6Al–4V. The results suggest that TNZS alloy might be a competitive biomaterial for orthopedic applications.Peer reviewe
Understanding Kulayni`s mentality in Al-Kafi Structure Engineering
Get PDFThe precious work of Al-Kafi book has been studied and explored from various viewpoints, but the gap for lack of conducting study about structure of this work may be well perceived and analysis of various viewpoints of this arrangement is a task for which the necessity is felt to take it as a model in today world. In this valuable work, author has designated a specific system, but he has not mentioned it in its introduction. Hence, we try to analyze the engineering system taken by Kulayni (author) in structure of book of Al-Kafi. In order to achieve this objective, the arrangement of volumes of this book and related chapters and existing narratives in them along with the method used in their codification and regulation of chapters of this work has been investigated. The present research results in general system of this clerical encyclopedia i.e. relationship between this religious encyclopedia and order existing among the relevant chapters and Islamic traditions (Hadith) in them- based on the goal considered for writing of this group of volumes. Namely, author has selected ideologies, ethics and Islamic injunctions and tried to posit a comprehensive book based on what he has referred to it in prologue of this book. Kulayni has also considered specific technique in terminology of chapters by which he has actually indexed the related bibliography.El precioso trabajo del libro de Al-Kafi ha sido estudiado y explorado desde varios puntos de
vista, pero la brecha por la falta de estudios sobre la estructura de este trabajo puede ser bien
percibida y el análisis de varios puntos de vista de este arreglo es una tarea para la cual es necesaria
la necesidad. Sentí tomarlo como modelo en el mundo de hoy. En este valioso trabajo, el autor ha
designado un sistema específico, pero no lo ha mencionado en su introducción. Por lo tanto,
tratamos de analizar el sistema de ingeniería adoptado por Kulayni (autor) en la estructura del
libro de Al-Kafi. Para lograr este objetivo, se ha investigado la disposición de los volúmenes de
este libro y los capítulos relacionados y las narraciones existentes en ellos, junto con el método
utilizado en su codificación y regulación de los capítulos de este trabajo. Los resultados de la
presente investigación en el sistema general de esta enciclopedia clerical, es decir, la relación
entre esta enciclopedia religiosa y el orden existente entre los capítulos relevantes y las tradiciones
islámicas (Hadith) en ellos, en función del objetivo considerado para la escritura de este grupo de
volúmenes. A saber, el autor seleccionó ideologías, ética y mandatos islámicos e intentó proponer
un libro completo basado en lo que se refirió a él en el prólogo de este libro. Kulayni también ha
considerado una técnica específica en la terminología de los capítulos mediante la cual ha
indexado la bibliografía relacionada
Effect of Quality Electrolyte Fluid on Removing MTBE from a Clay Soil Using Electrokinetic Technique
Get PDFThis is the author accepted manuscript. The final version is available from ASCE via the DOI in this recordMethyl tertiary butyl ether (MTBE) is a chemical product and the most commonly used gasoline oxygenate. It is characterized as a pollutant for soil and water that has effects on human health. Research on the remediation of soil polluted with MTBE is relatively rare. This paper presents the results of laboratory experiments to study the feasibility of using the electrokinetic technique to remove MTBE from a clay soil. Tests are conducted on a clay soil contaminated with MTBE in a special apparatus, using different quality of electrolyte and direct current (DC) or alternating current (AC) electricity. The results of the tests reveal that, under laboratory conditions, MTBE can be removed from soil using the electrokinetic technique. The efficiency of remediation is dependent on the quality of electrolyte and type of applied electrical current
A Study of the Impact of Organizational Social Capital on the Improvement of Knowledge Management in Yazd\\\'s Welfare Organization
No full textIntroduction
Organizational social capital is defined as a source of social relations within the organization. As a sort of collective criteria, social capital has a vital role in organizations and it is said to be a managerial phenomenon with strong emphasis on trust, common values, joint behaviors, communication, cooperation, mutual commitment, and networking. In fact, this type of capital is an important organizational capability, which can affect organizations for creation and distribution of knowledge. In other words, it is a sustainable organizational advantage. Usually, transferring information and knowledge at macro and micro levels among people and organizations depends on people who do such transmission urgently and fast. They can in fact influence the advancement of interpersonal relationships. Because of this, the importance of communication and interpersonal relationship among personnel based on trust plays a key role in developing and utilizing knowledge. If an organization can improve effective interpersonal relationships among its staff, groups and different departments, then information transaction may work effectively and an efficient management of organizational knowledge can be assured. In this regard, creating and developing a culture based on social capital is essential for knowledge management in organizations. Hence the author of this paper decided to study and examine the relationship between social capital, and different dimensions, processes and angles of knowledge management.
Material and Methods
To proceed with research methodology, first a deep and careful literature review took place in the context of social capital and knowledge management. Also, in order to implement and carry out the research, personnel of the Welfare Organization in Yazd Province were determined as statistical population. The sample size was calculated according to Cochran formula using random sampling method. In order to collect data, standard questionnaires were applied (Filliusetal (2000) for knowledge management and Ghoshal (1998) for social capital). Further, for data analysis, relevant statistical tools such as correlation coefficient and regression were applied.
Discussion of Results and Conclusion
The findings of the research show that there is a positive and significant relationship between knowledge management and social capital in the sense that with improvement in organizational social capital, knowledge management improves as well. Our findings showed that development of social capital in the Yazd's Welfare Organization strongly boost up knowledge management. Therefore, advancement in social capital leads to creation and transference of knowledge in the organization.
Other findings of the study also show that three dimensions of social capital reinforce knowledge management activities in organization. In other words, social, relational and structural capitals have positive and significant relationships with knowledge management. Because of what was found in this study, it is expected that significant relationships between dimensions of social capital and knowledge management lead to the advancement of knowledge management in any welfare organization.
In general and with respect to these findings, it is concluded that social organizations should try to promote their social capital for an effective management of organizational knowledge. They can invest in social capital by means of effective communicational training programs, and cultivating a proper climate in the relationships of managers and employees so they can become learning and creative organizations
Electrochemical behavior of additively manufactured patterned titanium alloys under simulated normal, inflammatory, and severe inflammatory conditions
Get PDFThe electrochemical behavior of a biomaterial surface in local conditions is a significant factor affecting the success of the implant placement. This is of a particular importance of metallic biomaterials which can undergo oxidation, corrosion and subsequent degradation. This study reports new data on the electrochemical behavior of additively manufactured (AM) patterned titanium alloys, analyzed after 1 and 12 h immersion in three different media mimicking normal, inflammatory and severe inflammatory conditions. Polarization study showed that corrosion resistance increases with increasing immersion time in all cases. It was found that in inflammatory condition a destructive effect on the passive layer's resistance was triggered by H2O2 whereas in severe inflammatory condition, albumin, lactate, and H2O2 all have a synergistic effect towards decreasing the corrosion resistance of patterned titanium layers. Electrochemical impedance data suggests that in the severe inflammatory condition the charged albumins are attracting to the localized pitting areas, changing diffusion transport of corrosive species at the interface of the metal/passive layer. The electrochemical tests also proven that laser-assisted patterned titanium alloys surfaces have an improved corrosion resistance in simulated solutions compared to untreated titanium of the same composition. It is suggested that new surface topography and wettability are also positive factors contributing to this improved corrosion performance in patterned specimens
On the importance and modeling of in-depth spectral radiation absorption in the pyrolysis of black PMMA
No full textFunding Information: The authors greatly acknowledge the support of the Academy of Finland under grant no. 314487 and the Finnish Fire Protection Fund (Palosuojelurahasto) . Publisher Copyright: © 2022 The Author(s)In-depth radiation absorption in pyrolysis models is commonly modeled with Beer's law using a constant absorption coefficient. This approximation neglects the effects of spectral variation of absorption coefficient, material emissions, and directional dependency of penetrated thermal radiation. This research aims to address the importance of these factors in flammability analysis of black poly(methyl methacrylate) (PMMA). Accordingly, a pyrolysis model including the separated full spectrum correlated k-distribution (SFSCK) method for spectral modeling, the ordinate weighting method (OWM) with finite volume method (FVM) for directional distribution of the thermal radiation is introduced as the most detailed model. By gradually simplifying this model, five other pyrolysis models are developed with different levels of details in radiation calculations. Simulations are first done using the optimized thermal conductivity and specific heat capacity for the most detailed model, then by optimizing these parameters for each pyrolysis model separately. The results show that the pyrolysis model with a depth and source temperature-dependent absorption coefficient, two-flux method, and diffuse boundary with a scenario-dependent effective reflectivity can predict the measured mass loss rate and ignition time with accuracy similar to the most detailed model, and can be recommended for future pyrolysis simulations.Peer reviewe
The ordinate weighting method for solving radiative heat transfer through a Fresnel interface
No full textFunding Information: The authors greatly acknowledge the support of the Academy of Finland under grant no. 314487 and the Finnish Fire Protection Fund (Palosuojelurahasto). Publisher Copyright: © 2021 The Author(s)Refraction of electromagnetic waves at Fresnel interfaces, i.e. the boundaries between media with different refractive indices, is important not only in explaining many natural phenomena but also in radiation heat transfer in energy conversion and combustion systems, such as solar energy, spray cooling and combustion, and the evaporation of liquid fuels in pool fires. This paper presents a novel model for the efficient consideration of Fresnel interfaces in the Finite Volume Method-based solvers of thermal radiation. By conserving the transmitted radiative heat flux at the Fresnel interface, the new model accurately estimates the directional distribution of radiative intensities on the second side of the interface. To do so, a matrix of weighting coefficients is obtained, representing the transferred radiation energy from the control angles on the first side of the Fresnel interface into each control angle on the second side. To assess the accuracy of the novel ordinate weighting method (OWM), its predictions are compared with the analytical solutions that we obtained for one- and two-layer slabs with various combinations of absorption and scattering properties. The validations are shown for normalized heat flux and irradiation, reflectivity, transmissivity, and intensity. The predictions of the OWM show an excellent agreement with the results of the analytical solutions. Compared to Murthy's pixelation method, the OWM method provides better accuracy with lower computational cost. Finally, the sensitivity of the OWM method to uniform and non-uniform directional discretizations, used in the finite volume solution of the radiative heat transfer, is investigated.Peer reviewe
