Search results

A computational structural mechanics approach, based on the exclusive use of standard bar elements is utilized in order to investigate the elastic stability of single-walled carbon nanotubes (SWCNTs) with atom vacancy defects under axial compressive loads. The paper aims to discuss this issue.

The proposed model uses three dimensional, two nodded, linear truss finite elements of three degrees of freedom per node to represent the force field appearing between carbon atoms due to the basic interatomic interactions.

Numerical results concerning the critical forces which cause instability of pristine nanotubes are compared with corresponding data given in the open literature in the effort to demonstrate the good accuracy of the method. Then, it is assumed that SWCNTs present-specific structural defects defined by their length, width, orientation and longitudinal position. The influence of these four geometric parameters of the imperfections considered on the stability of SWCNTs is investigated in detail and essential conclusions are revealed.

To the authors’ best knowledge, is the first time that the specific method is introduced for the prediction of buckling behavior of defective SWCNTs. The structural defect here is considered as atoms vacancy that forms a like-crack defect having a specific length, width, orientation and position along the nanotube length.

As compared with homogeneous metals and alloys, cellular metals provide low density, high specific stiffness, high energy absorption and good damping, thus being interesting alternatives to employ as protection against shock and impact. Impact energy is dissipated through cell bending, buckling or fracture. The knowledge and computational modelling of the mechanical behaviour of metal foams structures is thus of great importance for real life applications. The purpose of this paper is to increase the knowledge of the differences in metallic hollow sphere structures' (MHSS) behaviour under dynamic loading, as compared with the corresponding behaviour under static loading and to determine the influence of inertia and loading rate.

Computational dynamical finite element analyses of representative volume elements (RVE) of MHSS have been performed considering varying loading rates. Partially bonded geometries are considered and the effect of the spheres' distribution is also taken into account.

The results of the numerical examples presented show that inertia plays an important role in the dynamic behaviour of this kind of energy‐absorbing structure. When compared with the corresponding values in the quasi‐static case, the effect of inertia makes the peak load higher. If the deformation rate is higher (greater than 1.39 m/s in the studied cases), the characteristic plateau usually present in compressed metal foams can vanish. For the geometries analysed, damage has a small influence on load‐deformation relations.

This paper presents and discusses differences between static and dynamic behaviour of partially bonded MHSS. There are few references in the literature covering this issue by means of numerical analysis.

Hospital administration in the USA represents a rare instance of a female‐dominated occupation that masculinized. Advocacy for the change in social identity began in the early decades of the twentieth century and had succeeded by the second half of the century. The purpose of this paper is to explore the contribution of university programs in hospital administration to the change.

Analysis of the American Hospital Association's Guide to Hospitals, of journals published during the study period, and of archival material from universities, hospitals, as well as the American College of Healthcare Executives.

Graduate programs in hospital administration contributed to the occupation's masculinization because they admitted virtually no female students. At the same time, many hospitals switched to untrained male administrators even before graduates became available in significant numbers. This reflects normative and mimetic pressures to retain a male administrator per se. The appearance of male graduates then solidified the change in the occupation's social identity because hospitals that wanted to retain an executive with education in the field had no choice but to hire a man.

Knowledge of hospital management as an originally female‐dominated occupation has been recaptured only recently. This paper offers insight into an important aspect of this history in highlighting the effect on the occupation's social identity from educational programs that functioned as portals into the occupation and from professional associations that set norms for organizations in the field.

This paper attempts to cover the thermal processes in syntactic metal foams. Regularshaped cubic closed‐cell structures with spherical pores are investigated by means of the finite element method. Based on the numerical modelling of the microstructure, the effective macroscopic thermal properties are evaluated. Different relative densities (0.95 ‐ 0.5) and different base materials (aluminium and iron) are considered. Furthermore, the influence of the geometry, i.e. spherical ‐ cubical for 3D and circular ‐ rectangular for 2D models, is investigated. The focus is on such cellular materials where the transport of heat is dominated by solid conduction and thermal radiation; contributions from gaseous conduction and convection are neglected.

The purpose of this study is to understand the behavior of hybrid bio-composites under varied applications.

Fabrication methods and material characterization of various hybrid bio-composites are analyzed by studying the tensile, impact, flexural and hardness of the same. The natural fiber is a manufactured group of assembly of big or short bundles of fiber to produce one or more layers of flat sheets. The natural fiber-reinforced composite materials offer a wide range of properties that are suitable for many engineering-related fields like aerospace, automotive areas. The main characteristics of natural fiber composites are durability, low cost, low weight, high specific strength and equally good mechanical properties.

The tensile properties like tensile strength and tensile modulus of flax/hemp/sisal/Coir/Palmyra fiber-reinforced composites are majorly dependent on the chemical treatment and catalyst usage with fiber. The flexural properties of flax/hemp/sisal/coir/Palmyra are greatly dependent on fiber orientation and fiber length. Impact properties of flax/hemp/sisal/coir/Palmyra are depended on the fiber content, composition and orientation of various fibers.

This study is a review of various research work done on the natural fiber bio-composites exhibiting the factors to be considered for specific load conditions.

The social interaction between a deceiver and the deceived opponent is a determining factor for deception that involves emotions. Hence, besides a great amount of cognitive control, a successful lie also requires the regulation of emotions, especially when deceiving somebody face-to-face. The purpose of this paper is to investigate emotion regulation processes in an interpersonal lying experiment and aimed to examine whether fraudsters have well-functioning emotion regulation strategies or show a lack of emotional processes when deceiving face-to-face.

Imprisoned fraudsters (n=11), imprisoned violent offenders (n=10) and non-offenders (n=11) spontaneously deceived an interrogator in a face-to-face situation while the deceivers’ EEG was recorded.

The results showed that a decrease of alpha activity in left dorsolateral prefrontal cortex (dlPFC) predicted a higher frequency of deceptive responses as well as less guilt about deceiving the interrogator. These findings suggest a pivotal role of the left dlPFC in emotion regulation during deception for fraudsters, violent offenders and non-offenders. Unlike violent offenders, fraudsters did not show differences in alpha activity of the dlPFC between truthful and deceptive responses, suggesting that fraudsters are better at emotion regulation while deceiving their opponents.

This study emphasizes the recruitment of emotion regulation processes during deception. The results give first insight into the emotional processes underlying deception in fraudsters.

The purpose of this paper is to reveal the mechanism of graphene low-temperature friction and provide a theoretical basis for the application of graphene.

A probe etching model of graphene on the copper substrate was established to obtain the friction pattern of graphene with different layers in the temperature interval from 100 to 300 K. The friction mechanism was also explained from a microscopic perspective based on thermal lubrication theory. Low-temperature friction experiments of graphene were carried out by atomic force microscopy to further verify the graphene low-temperature friction law.

Graphene nanofriction experiments were conducted at 230–300 K. Based on this, more detailed simulation studies were performed. It is found that the combined effect of thermolubricity and thermal fluctuations affects the variation of friction. For monolayer graphene, thermolubricity is the main influence, and friction decreases with increasing temperature. For multilayer graphene, thermal fluctuations gradually become the main influencing factor as the temperature rises, and the overall friction becomes larger with increasing temperature.

Graphene with excellent mechanical properties provides a new way to reduce the frictional wear of metallic materials in low-temperature environments. The friction laws and mechanisms of graphene in low-temperature environments are of great significance for the expansion of graphene application environments.

The purpose of this paper is to detail the perceived influence of early gaming habits toward media production from seven students enrolled at a university in the Southeastern US. Participants identified as heavily involved in creating media such as anime, videos, fanfiction, webcomics, games, and digital music.

This exploratory study used qualitative research, thus data collection and analysis included questionnaires, interviews, and artifacts identifying and categorizing six main themes: game play preferences, persistence, early connections between game play and media, support and feedback, creations inspired by games, and significance of games in current lives.

The study found that most participants believed game play in childhood influenced increasingly complex media production habits. Six of the seven believed game play influenced their career path. The paper concludes with implications for education including games as conduits to personalized learning and career paths.

Results from this study extend prior research on the value of games to promote media production and meet personal and professional goals. This is significant as prior research linking early game play to media production influencing career goals is sparse.

Research in industrial and organizational psychology demonstrates that the regulation of negative emotions in response to both organizational stressors and interpersonal workplace interactions can result in functional and dysfunctional outcomes (Côté, 2005; Diefendorff, Richard, & Yang, 2008). Research on the regulation of negative emotions has additionally been conducted in social psychology, developmental psychology, neuropsychology, health psychology, and clinical psychology. A close reading of this broader literature, however, reveals that the conceptualization and use of the term “emotion regulation” varies within each research field as well as across these fields. The main focus of our chapter is to make sense of the term “emotion regulation” in the workplace by considering its use across a broad range of psychology disciplines. We then develop an overarching theoretical framework using disambiguating terminology to highlight what we argue are the important constructs involved in the process of intrapersonal emotion generation, emotional experience regulation, and emotional expression regulation in the workplace (e.g., emotional intelligence, emotion regulation strategies, emotion expression displays). We anticipate this chapter will enable researchers and industrial and organizational psychologists to identify the conditions under which functional regulation outcomes are more likely to occur and then build interventions around these findings.