Numerical study of the melting of nano-enhanced phase change material in a square cavity     

Seyed Sahand SEBTI  Mohammad MASTIANI  Hooshyar MIRZAEI  Abdolrahman DADVAND  Sina KASHANI  Seyed Amir HOSSEINI 《浙江大学学报(A卷英文版)》2013,14(5):307-316

A comprehensive numerical study was conducted to investigate heat transfer enhancement during the melting process in a 2D square cavity through dispersion of nanoparticles. A paraffin-based nanofluid containing various volume fractions of Cu was applied. The governing equations were solved on a non-uniform mesh using a pressure-based finite volume method with an enthalpy porosity technique to trace the solid-liquid interface. The effects of nanoparticle dispersion in a pure fluid and of some significant parameters, namely nanoparticle volume fraction, cavity size and hot wall temperature, on the fluid flow, heat transfer features and melting time were studied. The results are presented in terms of temperature and velocity profiles, streamlines, isotherms, moving interface position, solid fraction and dimensionless heat flux. The suspended nanoparticles caused an increase in thermal conductivity of nano-enhanced phase change material (NEPCM) compared to conventional PCM, resulting in heat transfer enhancement and a higher melting rate. In addition, the nanofluid heat transfer rate increased and the melting time decreased as the volume fraction of nanoparticles increased. The higher temperature difference between the melting temperature and the hot wall temperature expedited the melting process of NEPCM.  相似文献   

Quantitative estimation of dust fall and smoke particles in Quetta Valley     

Sami M  Waseem A  Akbar S 《Journal of Zhejiang University. Science. B》2006,7(7):542-547

INTRODUCTION Over the recent decades extensive research on atmospheric particles in urban environments was carried out. Most of the following papers refer to their authors’ contribution to air pollution and the effects on human health (Dzubay and Mamane, 1989; van Borm et al., 1989; 1990; Rojas et al., 1990; Paoletti et al., 1991; 1999; Al-Rajhi et al., 1996; McMurry et al., 1996; Querol et al., 1996; BéruBé et al., 1997; Esteve et al., 1997; Harrison et al., 1997; Zou and Hooper…  相似文献   

Comment on “Upgrading the Iranian National Laboratory Standard to Conform to ISO 15189:2012”     

Masoud Hajia  Amir Sohrabi 《Indian journal of clinical biochemistry : IJCB》2021,36(2):244

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An Integrated Holistic Method for Teaching Introductory German to Community College Students     

S. Amir N. Moosavi 《Community College Journal of Research & Practice》2013,37(10):797-812

The study reported in this paper investigated the effectiveness of an Integrated Holistic Teaching Method for teaching grammatical structure, cultural norms and behavior, writing and listening to German language students. The study involved a sample of 24 undergraduate students enrolled in an introductory college-level German course at a large urban community college in Texas. The research utilized a pre- and posttest design to study the instructional effectiveness of the Integrated Holistic Teaching Method. The higher posttest mean scores indicated significant improvement in student learning in the 4 major language skills areas as an artifact of involvement in the Integrated Holistic Teaching Method.  相似文献   

‘Brown Morning:’ classed interpretations of anti-racist text     

Dana Amir  Avihu Shoshana 《Critical Studies in Education》2018,59(1):108-126

This article examines the interpretations of high school students from different socioeconomic locations (in terms of socioeconomic class and ethnicity) with regard to the text Brown Morning, used as a didactic tool for antiracism education within the framework of Civics courses. The research findings uncover differences in the students’ interpretations of the text. An in-depth understanding of these differences will be attained through clinical analyses based on the distinctions between metaphor and metonymy made by linguist Roman Jakobson. Among students from low socioeconomic locations, interpretations related to racism were dominated by metonymic characteristics, while that of students from higher socioeconomic locations were predominantly metaphoric. Study findings do not only show the different interpretations among the students, but also the various ways in which metaphorical and metonymic language affect teachers. These analyses will focus on the reasons for these differences and their implications regarding the links between social locations, language, and education.  相似文献   

Soluble Tumor Necrosis Factor Like Weak Inducer of Apoptosis and Vitamin D in Hemodialysis Patients: Relation to Carotid Intima-Media Thickness     

Farahnaz Askarian  Amir Ghorbanihaghjo  Hassan Argani  Davoud Sanajou  Nima Nasehi  Roya Askarian  Ravan Ahmadi  Nadereh Rahtchizadeh 《Indian journal of clinical biochemistry : IJCB》2018,33(3):297-303

Cardiovascular disease, as the leading cause of patient death with chronic kidney disease, could be predicted by carotid atherosclerosis. The aim of the present study was to evaluate a possible relationship between serum soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK) and Vitamin D levels with mean right/left carotid intima-media thickness (cIMT), in the hemodialysis (HD) patients. In this cross-sectional study, serums were obtained from 50 stable chronic HD patients and 39 healthy controls. The serum levels of sTWEAK, Vitamin D, intact parathyroid hormone (iPTH) in both groups, and cIMT were determined in HD patients by standard methods. Serum levels of sTWEAK were higher [808.8 (521.6–5032.4) pg/ml vs. 664.4 (487.4–2955.8) pg/ml (p = 0.006)] and Vitamin D levels were lower [13.4 (2.5–153) ng/ml vs. 27.8 (18.4–59.0) ng/ml (p = 0.001)] in the hemodialysis patients than in the healthy control. No important correlation was found between sTWEAK Vitamin D levels (r = 0.010/p = 0.946), and mean right(r = ?0.194/p = 0.178) and left (r = 0.061/p = 0.673) cIMT in the HD patients. Our study shows that sTWEAK levels are elevated in HD patients. This elevation has no association with the cIMT.  相似文献   

The Thesis,the Pendulum and the Battlefield          下载免费PDF全文

Amir Ameri 《The International Journal of Art & Design Education》2015,34(1):121-131

The debate over the design thesis is often entangled in the dialectics of the practical and the theoretical. Whether the argument is waged and weighted in favour of a practical emphasis or a theoretical emphasis, or more insidious, a judicious balance between the two, what is inevitably assumed in the debate is the possibility of drawing and/or locating a dividing line between the practical and the theoretical. This article explores the inherent contradictions of this dichotomy, that make the traditional definition of thesis – a theorem or a hypothesis regarding the nature of the phenomenon under investigation – a problematic definition for architecture. Inasmuch as architecture is, in each iteration, a cultural construct, it is always and already the formal expression or embodiment of a theory. To avoid the tautology of positing a theorem about a theorem or a hypothesis regarding a hypothesis, the design thesis may be defined, not as a theorem or a hypothesis, but as an analytical posture assumed or a critical stance taken on the theorem that is or should be the phenomenon under investigation. In this case, the question to ask at the outset of a design thesis is not what patent ‘theory’ should the proposed building speak of, but what arcane theory does its type historically hide under the rubrics of ‘function’ or ‘practical’ requirements? It must begin, in other words, by de‐familiarising the familiar.  相似文献   

Characterizing the technology firm: An exploratory study   总被引：1，自引：0，他引：1  

Amir Grinstein ^{Author Vitae} 《Research Policy》2006,35(1):121-143

Technology firms occupy a central position in modern economies. They drive economic growth, productivity gains and have created new industries and innovative products.Many will agree that technology firms are distinguished from others in their emphasis on technological activities. Since this observation is too general, researchers suggested a variety of specific criteria and definitions. A number of definitions of technology firms appear in the literature but many are arbitrary and simplistic and none gained wide acceptance. Similarly, the number of characteristics suggested is large, reflecting a variety of perspectives and interests. In this case too no agreement exists as to which are the important ones. Also, many seem to be interrelated capturing different aspects of the same underlying concepts.This paper is concerned with the issue of definition and classification of technology firms. We demonstrate the usefulness of a different approach to the definition and classification problem. We rely on executives’ evaluations of their firms’ technology profile and level. An analysis of these evaluations reveals the underlying dimensions the executives used in making their judgments. We regard the dimensions we uncover as capturing the essence of technology firms and use them to classify the firms we study. The specific characteristics the executives used to evaluate their firms were derived from a systematic scan of the literature. Thus, the list represents the set of characteristics early researchers viewed as describing and defining technology firms. The connection to early work enhances our findings’ validity and lends some credence to our belief that the three dimensions we uncover (R&D activities which are closely associated with a set of organizational elements and market conditions, product strategy, and corporate culture) can be used by others to define technology firms and classify firms according to their technology level. In our study we use these three dimensions to classify the firms studied. We show that the commonly used practice of classifying firms as high and low technology according to the industry to which they belong is flawed.Our goal in this study is not to offer a “new” or “better” definition and characterization of technology firms or to offer the “best” approach to the generation of the classification criteria. Rather, we demonstrate here the usefulness of a different approach to the problem. While our approach does suffer from limitations it has important advantages. We hope future studies will confirm not only the usefulness of our approach but also the general applicability of the specific criteria we identify in this study.  相似文献   

Tragic mathematics: romantic narratives and the refounding of mathematics in the early nineteenth century     

Alexander AR 《Isis; an international review devoted to the history of science and its cultural influences》2006,97(4):714-726

A new, Romantic type of mathematical story appeared in the early nineteenth century that was radically different from the sober narrative characteristic of the previous generation of mathematicians. At the same time, a new mathematical practice emerged that differed sharply from the understanding and practice of mathematics during the Enlightenment. These parallel developments are inseparable: the new type of mathematical practice went hand in hand with the new mathematical story.  相似文献   

Human lung-on-chips: Advanced systems for respiratory virus models and assessment of immune response     

Ecem Saygili  Ece Yildiz-Ozturk  Macauley J. Green  Amir M. Ghaemmaghami  Ozlem Yesil-Celiktas 《Biomicrofluidics》2021,15(2)

Respiratory viral infections are leading causes of death worldwide. A number of human respiratory viruses circulate in all age groups and adapt to person-to-person transmission. It is vital to understand how these viruses infect the host and how the host responds to prevent infection and onset of disease. Although animal models have been widely used to study disease states, incisive arguments related to poor prediction of patient responses have led to the development of microfluidic organ-on-chip models, which aim to recapitulate organ-level physiology. Over the past decade, human lung chips have been shown to mimic many aspects of the lung function and its complex microenvironment. In this review, we address immunological responses to viral infections and elaborate on human lung airway and alveolus chips reported to model respiratory viral infections and therapeutic interventions. Advances in the field will expedite the development of therapeutics and vaccines for human welfare.  相似文献