Engineering the mechanical properties of graphene nanotube hybrid structures through structural modulation

The excellent multi-functional properties of carbon nanotube (CNT) and graphene have enabled them as appealing building blocks to construct 3D carbon-based nanomaterials or nanostructures. The recently reported graphene nanotube hybrid structure (GNHS) is one of the representatives of such nanostructures. This work investigated the relationships between the mechanical properties of the GNHS and its structure basing on large-scale molecular dynamics simulations. It is found that increasing the length of the constituent CNTs, the GNHS will have a higher Young’s modulus and yield strength. Whereas, no strong correlation is found between the number of graphene layers and Young’s modulus and yield strength, though more graphene layers intends to lead to a higher yield strain. In the meanwhile, the presences of multi-wall CNTs are found to greatly strengthen the hybrid structure. Generally, the hybrid structures exhibit a brittle behavior and the failure initiates from the connecting regions between CNT and graphene. More interestingly, affluent formations of monoatomic chains and rings are found at the fracture region. This study provides an in-depth understanding of the mechanical performance of the GNHSs while varying their structures, which will shed lights on the design and also the applications of the carbon-based nanostructures.

Vagueness and software engineering

We do not commonly associate software engineering with philosophical debate. Indeed, software engineers ought to be concerned with building software systems and not settling philosophical questions. I attempt to show that software engineers do, in fact, take philosophical sides when designing software applications. In particular, I look at how the problem of vagueness arises in software engineering and argue that when software engineers solve it, they commit to philosophical views that they are seldom aware of. In the second part of the paper, I suggest a way of dealing with vague predicates without having to confront the problem of vagueness itself. The purpose of my paper is to highlight the currently prevalent disconnect between philosophy and software engineering. I claim that a better knowledge of the philosophical debate is important as it can have ramifications for crucial software design decisions. Better awareness of philosophical issues not only produces better software engineers, it also produces better engineered products.

Managing identity transitions during radical change in nuclear engineering organizations

This study reports the construction and reconstruction of identities of new and existing employees during a significant transition phase of a nuclear engineering organization. We followed a group of new and existing employees over the period of three years, during which the organization constructed a greenfield nuclear facility with new generational technologies whilst in parallel, decommissioned the older reactor. This change led to the transfer and integration of existing trade-based employees with the newly recruited, primarily university educated graduates in the new site. Three waves of interview data were collected, in conjunction with the cognitive mapping of social grouping and photo elicitation portrayed the stories of different group of employees who either succeeded or failed at embracing their new professional identity. In contrast with the new recruits who constructed new identities as they join this organization, we identify and report on the number of enabling and disabling factors that influence the process of professional identity construction and reconstruction during gamma change.

Engineering thin film semiconductor gas sensors to increase sensitivity and decrease operation temperature

Thin film nanostructured gas sensors typically operate at temperatures above 400°C, but lower temperature operation is highly desirable, especially for remote area field sensing as this reduces significantly power consumption. We have investigated a range of sensor materials based on both pure and doped tungsten oxide (mainly focusing on Fe-doping), deposited using both thermal evaporation and electron-beam evaporation, and using a variety of post-deposition annealing. The films show excellent sensitivity at operating temperatures as low as 150°C for detection of NO2. There is a definite relationship between the sensitivity and the crystallinity and nanostructure obtained through the deposition and heat treatment processes, as well as variations in the conductivity caused both by doping and heat treatmetn. The ultimate goal of this work is to control the sensing properties, including selectivity to specific gases through the engineering of the electronic properties and the nanostructure of the films.

The aerospace engineering challenge

Integrating Science, Technology, and Engineering in Mathematics authors share ideas and activities that stimulate student interest in the integrated fields of science, technology, engineering, and mathematics (STEM) in K–grade 6 classrooms. This article describes an activity that introduced fourth-grade students to the work of aerospace engineers and to the science, technology, and mathematics principles associated with flight.

Can bone tissue engineering contribute to therapy concepts after resection of musculoskeletal sarcoma?

Resection of musculoskeletal sarcoma can result in large bone defects where regeneration is needed in a quantity far beyond the normal potential of self-healing. In many cases, these defects exhibit a limited intrinsic regenerative potential due to an adjuvant therapeutic regimen, seroma, or infection. Therefore, reconstruction of these defects is still one of the most demanding procedures in orthopaedic surgery. The constraints of common treatment strategies have triggered a need for new therapeutic concepts to design and engineer unparalleled structural and functioning bone grafts. To satisfy the need for long-term repair and good clinical outcome, a paradigm shift is needed from methods to replace tissues with inert medical devices to more biological approaches that focus on the repair and reconstruction of tissue structure and function. It is within this context that the field of bone tissue engineering can offer solutions to be implemented into surgical therapy concepts after resection of bone and soft tissue sarcoma. In this paper we will discuss the implementation of tissue engineering concepts into the clinical field of orthopaedic oncology.

Design, manufacturing and maintenance of sugar milling equipment : observations from the 2008 ISSCT Engineering Workshop

An International Society of Sugar Cane Technologists (ISSCT) Engineering Workshop was held in Piracicaba, Brazil from 30 June to 4 July 2008. The theme of the workshop was Design, manufacturing and maintenance of sugar mill equipment. The workshop consisted of a series of technical sessions and site visits. The Brazilian sugar industry is growing rapidly. The growth has occurred as the result of the sugar industry’s position as a key provider of renewable energy in the form of ethanol and, more recently, electricity. The increased focus on electricity is seeing investment in high pressure (100 bar) boilers, cane cleaning plants that allow an increased biomass supply from trash and digesters that produce biogas from dunder. It is clear that the Brazilian sugar industry has a well defined place in the country’s future. The ISSCT workshop provided a good opportunity to gain information from equipment suppliers and discuss new technology that may have application in Australia. The new technologies of interest included IMCO sintered carbide shredder hammer tips, Fives Cail MillMax mills, planetary mill gearboxes, Bosch Projects chainless diffusers, Fives Cail Zuka centrifugals and Vaperma Siftek membrane systems.

Morphometric analysis of telencephalic structure in a variety of neognath and paleognath bird species reveals regional differences associated with specific behavioral traits

Birds exhibit a huge array of behavior, ecology and physiology, and occupy nearly every environment on earth, ranging from the desert outback of Australia to the tropical rain forests of Panama. Some birds have adopted a fully nocturnal lifestyle, such as the barn owl and kiwi, while others, such as the albatross, spend nearly their entire life flying over the ocean. Each species has evolved unique adaptations over millions of years to function in their respective niche. In order to increase processing power or network efficiency, many of these adaptations require enlargements and/or specializations of the brain as a whole or of specific brain regions. In this study, we examine the relative size and morphology of 9 telencephalic regions in a number of Paleognath and Neognath birds and relate the findings to differences in behavior and sensory ecology. We pay particular attention to those species that have undergone a relative enlargement of the telencephalon to determine whether this relative increase in telencephalic size is homogeneous across different brain regions or whether particular regions have become differentially enlarged. The analysis indicates that changes in the relative size of telencephalic regions are not homogeneous, with every species showing hypertrophy or hypotrophy of at least one of them. The three-dimensional structure of these regions in different species was also variable, in particular that of the mesopallium in kiwi. The findings from this study provide further evidence that the changes in relative brain size in birds reflect a process of mosaic evolution.

Seasonal occurrence and distribution of Bryde's whales in the Hauraki Gulf, New Zealand

The Hauraki Gulf is a large, shallow embayment located north of Auckland City (36°51′S, 174°46′E), New Zealand. Bryde's whales (Balaenoptera edeni) are the most frequently observed balaenopterid in these waters. To assess the use of the Hauraki Gulf for this species, we examined the occurrence and distribution in relation to environmental parameters. Data were collected from a platform of opportunity during 674 daily surveys between March 2003 and February 2006. A total of 760 observations of Bryde's whales were recorded throughout the study period during 371 surveys. The number of Bryde's whales sighted/day was highest in winter, coinciding with the coolest median sea-surface temperature (14.6°C). Bryde's whales were recorded throughout the Hauraki Gulf in water depths ranging from 12.1–59.8 m (mean = 42.3, SD = 5.1). Cow–calf pairs were most frequently observed during the austral autumn in water depths of 29.9–53.9 m (mean = 40.8, SD = 5.2). Data from this study suggest Bryde's whales in the Hauraki Gulf exhibit a mix of both “inshore” and “offshore” characteristics from the Bryde's whales examined off the coast of South Africa. Based on complete mitochondrial DNA sequences, Sasaki et al. (2006) recognized two sister species of Bryde's whales: Balaenoptera brydei and B. edeni, with the latter including small-type, more coastal Bryde's whales from Japan, Hong Kong, and Australia. Their samples and samples in previous analyses of small-type whales, all originated from eastern and southeastern Asia. These authors did not include the forms of Bryde's whales that occur in other regions, e.g., in the Pacific off Peru (Valdivia et al. 1981), in the Atlantic off Brazil (Best 1977) and in the western Indian Ocean off South Africa (Best 1977). Recent genetic analysis using mtDNA from the “inshore” and “offshore” forms from South Africa confirms the offshore form is B. brydei, and establishes that the inshore form is more closely related to B. brydei than to B. edeni (Penry 2010). These different forms do vary considerably in their habitat use and ecology (refer to Table 1 for a detailed comparison between the South African inshore and offshore forms, as described by Best (1967, 1977) and the Bryde's whales from New Zealand (Wiseman 2008). Recent genetic analysis on the Bryde's whales in the Hauraki Gulf suggests they are B. brydei (Wiseman 2008). However, pending resolution of the uncertainty within and between species of this genus, we follow the Society of Marine Mammal's committee on taxonomy, who state that B. edeni applies to all Bryde's whales.

Axial capacity of barrette piles embedded in gravel layer

In this paper, the axial performance of two heavily instrumented barrette piles, with and without grouting, socket into gravel layer in Taipei are evaluated based on the results of pile load tests. Both piles are 44 m long with the same dimension of 0.8 by 2.7 m, installed by hydraulic long bucket. One of the piles with toe grouting was socket 6 m into gravel layer and the other pile without toe grouting was socket 3 m into gravel layer. The load versus displacement relationships at pile head, the t-z curves of upper soil layers and of bottom gravel layer, and the tip resistance versus displacement relationships are important concerns and are presented in the paper. The t-z curves interpreted from the measured data along depth are also simulated by the hyperbolic model.