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Hybrid Network (hybrid + network)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Chemistry	33%

Selected Abstracts

A Covalently Interconnected Phosphazene,Silicate Hybrid Network: Synthesis, Characterization, and Hydrogel Diffusion-Related Application,

ADVANCED MATERIALS, Issue 6 2003
Y. Chang
Sol,gel precursors of poly[bis(methoxyethoxyethoxy)phosphazene] have been synthesized by incorporating triethoxysilane in the polymer side groups. Studies of the water-swelling (see Figure, dry left, water-swollen, right) behavior and dye-release of the hybrid network indicate that the polyphosphazene,silicate network has potential as a biomaterial and for use in both passive and responsive membranes. [source]

A hybrid neural network for input that is both categorical and quantitative

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 10 2004
Roelof K. Brouwer
The data on which a MLP (multilayer perceptron) is normally trained to approximate a continuous function may include inputs that are categorical in addition to the numeric or quantitative inputs. Examples of categorical variables are gender, race, and so on. An approach examined in this article is to train a hybrid network consisting of a MLP and an encoder with multiple output units; that is, a separate output unit for each of the various combinations of values of the categorical variables. Input to the feed forward subnetwork of the hybrid network is then restricted to truly numerical quantities. A MLP with connection matrices that multiply input values and sigmoid functions that further transform values represents a continuous mapping in all input variables. A MLP therefore requires that all inputs correspond to numeric, continuously valued variables and represents a continuous function in all input variables. A categorical variable, on the other hand, produces a discontinuous relationship between an input variable and the output. The way that this problem is often dealt with is to replace the categorical values by numeric ones and treat them as if they were continuously valued. However there is no meaningful correspondence between the continuous quantities generated this way and the original categorical values. The basic difficulty with using these variables is that they define a metric for the categories that may not be reasonable. This suggests that the categorical inputs should be segregated from the continuous inputs as explained above. Results show that the method utilizing a hybrid network and separating numerical from quantitative input, as discussed here, is quite effective. © 2004 Wiley Periodicals, Inc. Int J Int Syst 19: 979,1001, 2004. [source]

Hybrid Bayesian networks: making the hybrid Bayesian classifier robust to missing training data

JOURNAL OF CHEMOMETRICS, Issue 5 2003
Nathaniel A. Woody
Abstract Many standard classification methods are incapable of handling missing values in a sample. Instead, these methods must rely on external filling methods in order to estimate the missing values. The hybrid network proposed in this paper is an extension of the hybrid classifier that is robust to missing values. The hybrid network is produced by performing empirical Bayesian network structure learning to create a Bayesian network that retains its classification ability in the presence of missing data in both training and test cases. The performance of the hybrid network is measured by calculating a misclassification rate when data are removed from a dataset. These misclassification curves are then compared against similar curves produced from the hybrid classifier and from a classification tree. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Effect of hybrid network formation on adhesion properties of polycyanurate/polyurethane semi-interpenetrating polymer networks

POLYMER ENGINEERING & SCIENCE, Issue 12 2002
O. Grigoryeva
The adhesion characteristics of modified polycyanurates based on the principle of semi-interpenetrating polymer networks (semi-IPNs) have been studied. It has been shown that the formation of a polycyanurate network in the presence of linear polyurethane (LPU) leads to increasing adhesion strength to aluminum and titanium. The peculiarities of polycyanurate network (PCN) formation in the presence of different amounts of LPU are discussed. It has been found that chemical incorporation of LPU into PCN occurs during network formation owing to chemical interaction of urethane groups with cyanate groups of growing PCN. At LPU content in the initial composition up to around 20 wt% only a hybrid network is formed. The maximal values of adhesive strength to aluminum and titanium are achieved at LPU content of 20,25%, corresponding to formation of a hybrid network. The further increase of LPU content leads to the presence of non-incorporated LPU (semi-IPN formation) in the adhesive layer and to reduction of the adhesive strength. [source]

Oligomeric Alkoxysilanes with Cagelike Hybrids as Cores: Designed Precursors of Nanohybrid Materials

CHEMISTRY - AN ASIAN JOURNAL, Issue 3 2008
Hideki Kuge
Abstract Well-defined alkoxysilane oligomers containing a cagelike carbosiloxane core were synthesized and used as novel building blocks for the formation of siloxane-based hybrid networks. These oligomers were synthesized from the cagelike trimer derived from bis(triethoxysilyl)methane by silylation with mono-, di-, and triethoxychlorosilanes ((EtO)nMe3,nSiCl, n=1, 2, and 3). Hybrid xerogels were prepared by hydrolysis and polycondensation of these oligomers under acidic conditions. The structures of the products varied depending on the number of alkoxy groups (n). When n=2 and 3, microporous xerogels (BET surface areas of 820 and 510,m2,g,1, respectively) were obtained, whereas a nonporous xerogel was obtained when n=1. 29Si,NMR spectroscopic analysis suggested that partial rearrangement of the siloxane networks, which accompanied the cleavage of the Si,O,Si linkages, occurred during the polycondensation processes. By using an amphiphilic triblock copolymer surfactant as a structure-directing agent, hybrid thin films with a 2D hexagonal mesostructure were obtained when n=2 and 3. These results provide important insight into the rational synthesis of molecularly designed hybrid materials by sol,gel chemistry. [source]