A computational analysis of under-expanded jets in the hypersonic regime

Underexpanded axisymmetric jets are studied numerically using a full Navier-Stokes solver. Emphasis has been given to supersonic and hypersonic jets in supersonic and hypersonic ambient flows, a phenomenon previously overlooked. It is demonstrated that the shear layers and shock patterns in a jet plume can be captured without complicated viscous/inviscid and subsonic/supersonic coupling schemes. In addition, a supersonic pressure relief effect has been identified for underexpanded jets in supersonic ambient flows. While it is well known that an underexpanded jet in a quiescent ambience (or subsonic ambience) contains multiple shock cells, the present study shows that because of the supersonic pressure relief effect, an underexpanded jet in a supersonic or hypersonic ambience contains only one major shock cell

Binary object recognition system on FPGA with bSOM

Tri-state Self Organizing Map (bSOM), which takes binary inputs and maintains tri-state weights, has been used for classification rather than clustering in this paper. The major contribution here is the demonstration of the potential use of the modified bSOM in security surveillance, as a recognition system on FPGA

Intergenerational Income Mobility in Urban China

This paper estimates the intergenerational income elasticity for urban China, paying careful attention to the potential biases induced by income fluctuations and life cycle effects. Our preferred estimates are that the intergenerational income elasticities are 0.74 for father-son, 0.84 for father-daughter, 0.33 for mother-son, and 0.47 for mother-daughter. This suggests that while China has experienced rapid growth of absolute incomes, the relative position of children in the distribution is largely determined by their parents’ incomes. Investigating possible causal channels, we find that parental education, occupation, and Communist Party membership all play important roles in transmitting economic status from parents to children.intergenerational mobility, transgenerational persistence, political party membership

Innovation, Internationalisation and the Performance of Microbusinesses

This article integrates internationalisation, and specifically exporting, into a conceptualisation of how innovation production leads to productivity performance in microbusinesses employing less than ten people. Innovation production is reframed for the microbusiness context by focusing on knowledge acquisition and formalisation rather than on R&D activity. Propensity score matching analysis is used to investigate British microbusiness survey data. It finds a causal process in which innovation promotes exporting activity. This in turn leads to improved productivity. In contrast to research on larger businesses, the study finds no direct link between innovation production and productivity. These findings are robust to various checks for potential endogeneity arising from feedback into innovation from internationalisation and from self-selection of high productivity firms into exporting

Wrapping up the bad news: HIV assembly and release.

The late Nobel Laureate Sir Peter Medawar once memorably described viruses as 'bad news wrapped in protein'. Virus assembly in HIV is a remarkably well coordinated process in which the virus achieves extracellular budding using primarily intracellular budding machinery and also the unusual phenomenon of export from the cell of an RNA. Recruitment of the ESCRT system by HIV is one of the best documented examples of the comprehensive way in which a virus hijacks a normal cellular process. This review is a summary of our current understanding of the budding process of HIV, from genomic RNA capture through budding and on to viral maturation, but centering on the proteins of the ESCRT pathway and highlighting some recent advances in our understanding of the cellular components involved and the complex interplay between the Gag protein and the genomic RNA.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Covalently bonded interfaces for polymer/graphene composites

The interface is well known for taking a critical role in the determination of the functional and mechanical properties of polymer composites. Previous interface research has focused on utilising reduced graphene oxide that is limited by a low structural integrity, which means a high fraction is needed to produce electrically conductive composites. By using 4,40-diaminophenylsulfone, we in this study chemically modified high-structural integrity graphene platelets (GnPs) of 2–4 nm in thickness, covalently bonded GnPs with an epoxy matrix, and investigated the morphology and functional and mechanical performance of these composites. This covalently bonded interface prevented GnPs stacking in the matrix. In comparison with unmodified composites showing no reduction in electrical volume resistivity, the interface-modified composite at 0.489 vol% GnPs demonstrates an eight-order reduction in the resistivity, a 47.7% further improvement in modulus and 84.6% in fracture energy release rate. Comparison of GnPs with clay and multi-walled carbon nanotubes shows that our GnPs are more advantageous in terms of performance and cost. This study provides a novel method for developing interface-tuned polymer/graphene composites

Accelerated hardware video object segmentation: From foreground detection to connected components labelling

This is the preprint version of the Article - Copyright @ 2010 ElsevierThis paper demonstrates the use of a single-chip FPGA for the segmentation of moving objects in a video sequence. The system maintains highly accurate background models, and integrates the detection of foreground pixels with the labelling of objects using a connected components algorithm. The background models are based on 24-bit RGB values and 8-bit gray scale intensity values. A multimodal background differencing algorithm is presented, using a single FPGA chip and four blocks of RAM. The real-time connected component labelling algorithm, also designed for FPGA implementation, run-length encodes the output of the background subtraction, and performs connected component analysis on this representation. The run-length encoding, together with other parts of the algorithm, is performed in parallel; sequential operations are minimized as the number of run-lengths are typically less than the number of pixels. The two algorithms are pipelined together for maximum efficiency

A binary self-organizing map and its FPGA implementation

A binary Self Organizing Map (SOM) has been designed and implemented on a Field Programmable Gate Array (FPGA) chip. A novel learning algorithm which takes binary inputs and maintains tri-state weights is presented. The binary SOM has the capability of recognizing binary input sequences after training. A novel tri-state rule is used in updating the network weights during the training phase. The rule implementation is highly suited to the FPGA architecture, and allows extremely rapid training. This architecture may be used in real-time for fast pattern clustering and classification of the binary features

‘Health first, safety first’:An analysis of the legal system and professional ethics for curriculum enactment in China

Nation-states have concerns about the health and wellbeing of their citizens and these concerns have directly or indirectly influenced educational reform and curriculum development. In 2000, China issued a directive of ‘Health First’ which applied to all elements of the education system. In its scale and scope, this represented a significant and far-reaching reform, ushering in a period where school leaders and teachers were expected to engage with new policy documents and develop curriculum practices to reflect the ambitions of ‘Health First’. This article provides an opportunity to explore the complex and dynamic processes of teachers’ curriculum enactment within the broader socio-political context. Our analysis offers a unique insight into the legal system in China and how this played an important role in teachers’ decision-making and professional practice. Guided initially by grounded theory, 22 physical education teachers in the north of mainland China were interviewed to explore their experiences of the reform to the curriculum. To develop a better understanding of how ‘Health First’ was taken up and enacted by teachers and specifically recognising the characteristics of a non-western research context, we deployed two theoretical concepts–‘technologies of the self’ and ‘self-cultivation’. Our findings reveal, rather than prioritising ‘Health First’, curriculum enactment was predicated on ‘safety first’ as a result of the complex interplay between teachers’ awareness of the legal system and their professional ethics, which led to these teachers interpreting the maxim of ‘Health First’ as ‘safety first’.</p