Surface morphologies and internal fine structures of bast fibers

Fiber surface morphologies and associated internal structures are closely related to its properties. Unlike other fibers including cotton, bast fibers possess transverse nodes and fissures in cross-sectional and longitudinal directions. Their morphologies and associated internal structures were anatomically examined under the scanning electron microscope. The results showed that the morphologies of the nodes and the fissures of bast fibers varied depending on the construction of the inner fibril cellular layers. The transverse nodes and fissures were formed by the folding and spiralling of the cellular layers during plant growth. The dimensions of nodes and fissures were determined by the dislocations of the cellular layers. There were also many longitudinal fissures in bast fibers. Some deep longitudinal fissures even opened the fiber lumen for a short way along the fiber. In addition, the lumen channel of the bast fibers could be disturbed or disrupted by the nodes and the spirals of the internal cellular layers. The existence of the transverse nodes and fissures in the bast fibers could degrade the fiber mechanical properties, whereas the longitudinal fissures may contribute to the very rapid moisture absorption and desorption.

Multi-cluster computing interconnection network performance modeling and analysis

The overall performance of a distributed system is often depends on the effectiveness of its interconnection network. Thus, the study of the communication networks for distributed systems is very important, which is the focus of this paper. In particular, we address the problem of fat-tree based interconnection networks performance modeling for multi-user heterogeneous multi-cluster computing systems. To this end, we present an analytical model and validate the model through comprehensive simulation. The results of the simulation demonstrated that the proposed model exhibits a good degree of accuracy for various system organizations and under different working conditions.

Formation of ultra-fine ferrite in hot rolled strip: potential mechanisms for grain refinement

A novel single-pass hot strip rolling process has been developed in which ultra-fine (<2 μm) ferrite grains form at the surface of hot rolled strip in two low carbon steels with average austenite grain sizes above 200 μm. Two experiments were performed on strip that had been re-heated to 1250°C for 300 s and air-cooled to the rolling temperatures. The first involved hot rolling a sample of 0.09 wt.%C–1.68Mn–0.22Si–0.27Mo steel (steel A) at 800°C, which was just above the Ar3 of this sample, while the second involved hot rolling a sample of 0.11C–1.68Mn–0.22Si steel (steel B) at 675°C, which is just below the Ar3 temperature of the sample. After air cooling, the surface regions of strip of both steel A and B consisted of ultra-fine ferrite grains which had formed within the large austenite grains, while the central regions consisted of a bainitic microstructure. In the case of steel B, a network of allotriomorphic ferrite delineated the prior-austenite grain boundaries throughout the strip cross-section. Based on results from optical microscopy and scanning/transmission electron microscopy, as well as bulk X-ray texture analysis and microtextural analysis using Electron Back-Scattered Diffraction (EBSD), it is shown that the ultra-fine ferrite most likely forms by a process of rapid intragranular nucleation during, or immediately after, deformation. This process of inducing intragranular nucleation of ferrite by deformation is referred to as strain-induced transformation.

Fine motor difficulties: the need for advocating for the role of occupational therapy in schools

Background: Fine motor difficulties can impact on the academic, social and emotional development of a student. Aim: The aims of this paper are to: (i) investigate the need for support to students experiencing fine motor  difficulties from the perspective of their classroom teachers, and (ii) report on the level of knowledge teachers have in regard to the role of occupational therapists in supporting students with fine motor difficulties.  Methods: Fifteen teachers from a stratified random sample of public schools within two regions of Victoria, Australia, were interviewed in this qualitative, grounded theory investigation. Results: Results showed that the current level of support for students with fine motor difficulties is inadequate. Conclusion: Occupational therapists in Victoria need to advocate their role in developing the fine motor skills of students at both an organisational and an individual level in order to increase the access of students with fine motor difficulties to occupational therapy services.

Analytical modeling of interconnection networks in heterogeneous multi-cluster systems

In data-intensive distributed systems, replication is the most widely used approach to offer high data availability, low bandwidth consumption, increased fault-tolerance and improved scalability of the overall system. Replication-based systems implement replica control protocols that enforce a specified semantics of accessing the data. Also, the performance depends on a number of factors, the chief of which is the protocol used to maintain consistency among object replica. In this paper, we propose a new low-cost and high data availability protocol called the box-shaped grid structure for maintaining consistency of replicated data on networked distributed computing systems. We show that the proposed protocol provides high data availability, low communication costs, and increased fault-tolerance as compared to the baseline replica control protocols.

Optimal multicast tree routing for cluster computing in hypercube interconnection networks

Cluster computation has been used in the applications that demand performance, reliability, and availability, such as cluster server groups, large-scale scientific computations, distributed databases, distributed media-on-demand servers and search engines etc. In those applications, multicast can play the vital roles for the information dissemination among groups of servers and users. This paper proposes a set of novel efficient fault-tolerant multicast routing algorithms on hypercube interconnection of cluster computers using multicast shared tree approach. We present some new algorithms for selecting an optimal core (root) and constructing the shared tree so as to minimize the average delay for multicast messages. Simulation results indicate that our algorithms are efficient in the senses of short end-to-end average delay, load balance and less resource utilizations over hypercube cluster interconnection networks.

Performance analysis of interconnection networks for multi-cluster systems

With the current popularity of cluster computing systems, it is increasingly important to understand the capabilities and potential performance of various interconnection networks. In this paper, we propose an analytical model for studying the capabilities and potential performance of interconnection networks for multi-cluster systems. The model takes into account stochastic quantities as well as network heterogeneity in bandwidth and latency in each cluster. Also, blocking and non-blocking network architecture model is proposed and are used in performance analysis of the system. The model is validated by constructing a set of simulators to simulate different types of clusters, and by comparing the modeled results with the simulated ones.

Analysis of interconnection networks in heterogeneous multi-cluster systems

The study of interconnection networks is important because the overall performance of a distributed system is often critically hinged on the effectiveness of its interconnection network. In the mean time, the heterogeneity is one of the most important factors of such systems. This paper addresses the problem of interconnection networks performance modeling of large-scale distributed systems with emphases on heterogeneous multi-cluster computing systems. So, we present an analytical model to predict message latency in multi-cluster systems in the presence of cluster size heterogeneity. The model is validated through comprehensive simulation, which demonstrates that the proposed model exhibits a good degree of accuracy for various system organizations and under different working conditions.

Analytical interconnection networks model for multi-cluster computing systems

This paper addresses the problem of interconnection networks performance modeling of large-scale distributed systems with emphases on multi-cluster computing systems. The study of interconnection networks is important because the overall performance of a distributed system is often critically hinged on the effectiveness of its interconnection network. We present an analytical model that considers stochastic quantities as well as processor heterogeneity of the target system. The model is validated through comprehensive simulation, which demonstrates that the proposed model exhibits a good degree of accuracy for various system sizes and under different operating conditions.