Processing and properties of metal-ceramic interpenetrating composites

Composite materials consisting of two or more different phases are very extensively used in modern society. If the composite is designed and fabricated correctly, then desirable properties not available in any single conventional material can be achieved. Ceramic reinforced aluminium alloys are desired for high performance applications due to their superior properties compared with the soft, unreinforced metal. However "traditional" particle or fibre reinforced composites suffer from a limited ability to achieve high reinforcement levels. Interpenetrating composites (IPCs) have 3-3 connectivity, with both the matrix and reinforcement phases being fully connected; they are expected to provide truly multifunctional properties. Whilst pressure is normally needed for the processing of IPCs due to the poor wetting between most aluminium alloys and ceramic materials, it raises the risk of ceramic preform damage and limits the component shape. In this research, interpenetrating composites were produced at atmospheric pressure by infiltrating 10 wt% magnesium content Al-Mg alloys into 15-40% dense, gel-cast ceramic foams with average cell sizes from 100 to 500 μm, made from three different ceramics. Previous research at Loughborough University focused on the aluminium / alumina system. In this study, the ceramic foams were made from spinel, mullite and silicon carbide. Effects of processing parameters, including atmosphere, temperature and time, were investigated. The results showed that heating the metal-ceramic couple in Ar and infiltrating in N2 followed by cooling in Ar was a better approach for the infiltration process than heating in N2 during the whole process. The Al(Mg)/spinel system was observed to require the lowest processing temperature and shortest time compared with the Al(Mg)/mullite and Al(Mg)/alumina systems. Microstructures of IPCs were characterised using a series of techniques, including optical microscopy, field emission gun scanning electron microscopy (FEG SEM), X-ray diffraction (XRD), dual beam focused ion beam (DBFIB) and transmission electron microscopy (TEM). A continuous nitride layer consisting of AlN and Mg3N2 was observed at the metal-ceramic interface of the spinel and mullite-based IPCs ABSTRACT ii with MgO and MgAl2O4 observed at localised positions, similar to alumina-based composites. Based on these results, a two-step nitridation infiltration mechanism has been proposed for oxide ceramic foam / aluminium-magnesium IPCs. The infiltration is believed to be dependent on the reaction between Mg and N2 to form Mg3N2, which then deposits onto the oxide ceramic foam surface; once in contact with molten Al, Mg3N2 reacts with the Al to form AlN, which is wetted by the liquid aluminium and induced the infiltration. In the case of mullite-based composites, a small amount of Mg2Si was observed as a result of the reactions between the SiO2 phase in the mullite foam and the liquid metal. The feasibility of fabricating SiC foam / Al-Mg and SiC foam / Al-Si IPCs by pressureless infiltration of molten Al alloys into gel-cast SiC foams has been also evaluated in this research. Serious degradation of the SiC foam was observed in the SiC / Al-Mg IPCs, resulting in the formation of Mg2Si and Al4C3, whilst the SiC foam could not be spontaneously infiltrated by the Al-Si alloy without the presence of Mg. A modified pressureless infiltration technique was developed to allow the manufacture of fully infiltrated SiC foam / Al-Si interpenetrating composites, with little degradation of the SiC foam and very little formation of detrimental phases. Preliminary property characterisation showed that the ceramic-foam based IPCs were up to twice as wear resistant as composites made by infiltrating a bed of ceramic powder. Effects of parameters on wear resistance have been investigated, including the ceramic material, foam density, cell size and degree of sintering. The denser the ceramic foam, the stronger the foam struts, and hence the more effective the composites were in resisting wear. However, a non-linear relationship between the foam cell size and the wear rate was observed; the composites with moderate mean foam cell sizes exhibited better properties than composites with smaller or larger cell sizes. Thermal expansion behaviour of the IPCs has been also studied; a clear hysteresis was observed in the strain curve between heating and cooling. The coefficient of thermal expansion (CTE) was observed to vary as a function of temperature

Perancangan Sistem Otomatis Update pada Aplikasi Desktop Abios

Unlike web applications easier to update the latest version, desktop applications more difficult and must involve the user in doing so. It is caused by a desktop application is an application that is installed in the computer user. The purpose of this research is to design an automatic system updates on a desktop application, an example case: Application Binus International Operational Support (ABIOS). This research used literature study and system design. In desktop applications, often there is update the latest applications that are not known to the user who sometimes fatal and disrupt business operations. Generally, developer will inform the changes version to user that they can update the application. In an update of applications, should be done by the system automatically, not manually by users. Once in a while, the user background is not from computer base. After doing the research, it can be concluded that the system automatically updates the application has benefits to users in obtaining information regarding the latest version, and can assist in automatically update the latest application is based on computerization. For further development of this system is expected to operate on multi platforms and or mobile applications

Analysis of gender differences in speech and hand gesture coordination for the design of multimodal interface systems

The research studies about Multimodal Interface Systems (MMIS) involving speech and hand gestures have intensified in the past three decades. Understanding the correlations of speech and hand gestures has gained significance in MMIS design. Gesture is known to correlate with speech in a number of levels in general, but less is known about the gender differences in this kind of correlation. When users interact multimodally with MMIS, we hypothesise that there are gender differences in the coordination of speech and hand gestures internally and externally. The investigation of such user related factors can benefit MMIS through accommodating gender adaptive processing strategies for different gender groups which can potentially improve the system performance. The main methodology used in this thesis is video annotation, including hand gesture annotation and speech annotation, to identify the gender differences in the descriptions of two objects using speech and hand gestures. Our aim is to search for answers to the following questions: Firstly, are there any gender differences in the coordination of speech and hand gestures? We found that females use more hand gestures than males for the same task. This may imply that females and males have different preferences in using speech and gestural modalities in MMIS. The temporal integration patterns are similar for males and females, but the temporal alignment intervals of gesture strokes and corresponding lexical affliates are shorter for females than males. Secondly, do males and females employ different cognitive processing models in the coordination of speech and hand gestures? Our findings demonstrated that males and females have different distribution in cognitive actions. In general, males have more perceptual actions than functional actions, while females have more functional actions than perceptual actions. Gender differences in cognitive processing models might be the reason for the differences in the distribution of word types accompanying hand gestures. This implies that MMIS can potentially achieve better performance if information processing strategies are designed for different gender groups. Thirdly, are there any differences in brain activities of males and females, when speech accompanies hand gestures? Our findings showed that the differences in lateralisation of brain activities associated with speech and hand gestures are quite minor in gender. However, we found that females show stronger beta spectral moment and more significant changes in spectral moment from alpha to beta band. This may explain the shorter temporal alignment of speech and hand gestures for females. We demonstrated that gender differences in speech and hand gestures occur both internally (in cognitive processing and brain activities) and externally (in the presentation of speech and hand gestures). Based on the external differences, we developed models to predict the gender of users by evaluating their multimodal actions (using decision tree, neural network and logistic regression respectively). Our results show that a reasonable performance can be achieved by logistic regression model with an accuracy over 70%. Thus, we demonstrated that various gender prediction models can be successfully implemented using our findings and our results are promising for the design of gender adaptive MMIS

Spontaneous Dispersion and Large-Scale Deformation of Gallium-Based Liquid Metal Induced by Ferric Ions

A gallium-based liquid metal (LM) exhibits the largest interfacial tension among all the room-temperature liquids, which gives it strong deformability and promises its role in the field of soft machines. Paradoxically, such a material always remains nearly spherical in solution because of large interfacial tension, which in turn hinders the construction of LM-based soft machines. Consequently, it is of significant theoretical and practical value to regulate the interfacial tension of a LM in order to carry out richer deformation. In this study, spontaneous dispersion and large-scale deformation of a bulk LM were disclosed to be induced by ferric ions. It was found that the bulk LM immersed in the FeCl3 solution can spontaneously disperse into a large amount of droplets. In addition, the dispersed LM droplets could move and deform by increasing the concentration of the solution or adding acids. The mechanisms behind the untraditional phenomena lie in the nonuniform interfacial tension over the entire surface of the LM, which is associated with the space–time distribution of the FeCl3 solution. Further, directional locomotion and periodic oscillation occur because of the nonuniform interfacial tension, which leads to the autonomous dispersion and deformation of the LM. Overall, the unique redox reactions between the LM and the FeCl3 solution play an essential role in ensuring the continuity of deformation. The present spontaneous dispersion and deformation capability of the LM signify a paradigm shift and open up new possibilities for the development of chemistry-enabled soft machines in the future

The predictive value of GLR, glucose, and lymphocytes on in-hospital mortality.

The predictive value of GLR, glucose, and lymphocytes on in-hospital mortality.</p

Spontaneous Dispersion and Large-Scale Deformation of Gallium-Based Liquid Metal Induced by Ferric Ions

A gallium-based liquid metal (LM) exhibits the largest interfacial tension among all the room-temperature liquids, which gives it strong deformability and promises its role in the field of soft machines. Paradoxically, such a material always remains nearly spherical in solution because of large interfacial tension, which in turn hinders the construction of LM-based soft machines. Consequently, it is of significant theoretical and practical value to regulate the interfacial tension of a LM in order to carry out richer deformation. In this study, spontaneous dispersion and large-scale deformation of a bulk LM were disclosed to be induced by ferric ions. It was found that the bulk LM immersed in the FeCl3 solution can spontaneously disperse into a large amount of droplets. In addition, the dispersed LM droplets could move and deform by increasing the concentration of the solution or adding acids. The mechanisms behind the untraditional phenomena lie in the nonuniform interfacial tension over the entire surface of the LM, which is associated with the space–time distribution of the FeCl3 solution. Further, directional locomotion and periodic oscillation occur because of the nonuniform interfacial tension, which leads to the autonomous dispersion and deformation of the LM. Overall, the unique redox reactions between the LM and the FeCl3 solution play an essential role in ensuring the continuity of deformation. The present spontaneous dispersion and deformation capability of the LM signify a paradigm shift and open up new possibilities for the development of chemistry-enabled soft machines in the future

Spontaneous Dispersion and Large-Scale Deformation of Gallium-Based Liquid Metal Induced by Ferric Ions

A gallium-based liquid metal (LM) exhibits the largest interfacial tension among all the room-temperature liquids, which gives it strong deformability and promises its role in the field of soft machines. Paradoxically, such a material always remains nearly spherical in solution because of large interfacial tension, which in turn hinders the construction of LM-based soft machines. Consequently, it is of significant theoretical and practical value to regulate the interfacial tension of a LM in order to carry out richer deformation. In this study, spontaneous dispersion and large-scale deformation of a bulk LM were disclosed to be induced by ferric ions. It was found that the bulk LM immersed in the FeCl3 solution can spontaneously disperse into a large amount of droplets. In addition, the dispersed LM droplets could move and deform by increasing the concentration of the solution or adding acids. The mechanisms behind the untraditional phenomena lie in the nonuniform interfacial tension over the entire surface of the LM, which is associated with the space–time distribution of the FeCl3 solution. Further, directional locomotion and periodic oscillation occur because of the nonuniform interfacial tension, which leads to the autonomous dispersion and deformation of the LM. Overall, the unique redox reactions between the LM and the FeCl3 solution play an essential role in ensuring the continuity of deformation. The present spontaneous dispersion and deformation capability of the LM signify a paradigm shift and open up new possibilities for the development of chemistry-enabled soft machines in the future

Characteristics of eligible patients with different levels of GLR.

Characteristics of eligible patients with different levels of GLR.</p

Trends in ₅<i>q</i>₀ in Rwanda 2000 and 2005 DHS surveys using calendar-year estimation periods.

<p>Trends in ₅<i>q</i>₀ in Rwanda 2000 and 2005 DHS surveys using calendar-year estimation periods.</p