Adaptive control optimization in end milling using neural networks

In this paper, we propose an architecture with two different kinds of neural networks for on-line determination of optimal cutting conditions. A back-propagation network with three inputs and four outputs is used to model the cutting process. A second network, which parallelizes the augmented Lagrange multiplier algorithm, determines the corresponding optimal cutting parameters by maximizing the material removal rate according to appropriate operating constraints. Due to its parallelism, this architecture can greatly reduce processing time and make real-time control possible. Numerical simulations and a series of experiments are conducted on end milling to confirm the feasibility of this architecture.     

HEAT TRANSFER IN PARTIALLY MISCIBLE TERNARY SYSTEMS

In the study of mass transfer between partially miscible liquids, temperature perturbations have been found to have an important effect in the generation of interfacial activity. Micro- and macro-generated interfacial convection usually occurs in combination with one another even in fairly simple heat or mass transfer events. These combinations are responsible for the enhancement of mass transfer rates. In an effort to acquire a better understanding of the heat transfer effects in ternary liquid-liquid systems, temperature difference profiles were measured when contacting two partially miscible phases. A vertical and a rotational transfer cell were designed to contact the partially miscible phases without inducing external disturbances. Five thermocouples were immersed in the bottom liquid phase at predetermined positions below the interface. In order to understand the influence of the convection generated, the vertical cell was designed to hinder convection in one phase, while the rotational cell permits convection in both phases. The experimental results showed larger temperature differences in the rotational cell after the contact of the phases. Also, systems which were initially unsaturated presented larger heat effects than those in which the partially miscible solvents were initially saturated. Several parameters indicating the importance of heat effects in the ternary systems studied are reported.     

Polypropylene composites. II: Structure-property relationships in two- and three-component polypropylene composites

Two- and three-component polypropylene (PP) blends and composites were prepared to study their structure/property relationships. Butadiene-styrene (BDS) copolymers of low compatibility formed large particles of poor adhesion in PP resulting in inferior mechanical properties. Better miscibility of ethylene-propylene-diene (EPDM) elastomer results in more finely dispersed particles and the experimental results indicate a transition to an interpenetrating network (IPN)– like structure with increasing elastomer content. Effective impact modification can be achieved only with EPDM elastomers of sufficient miscibility. Mutual wettability and adhesion of the components determine the structure and properties in PP/elastomer/filler systems. Modification of PP by acrylic acid grafting promotes PP/filler adhesion which, in turn, results in the separate dispersion of the components. In an unmodified PP matrix, a significant amount of the filler is encapsulated by the elastomer. At low filler content, better low temperature impact strength is achieved in the case of separately dispersed components, while encapsulation is more advantageous at high filling grades.     

Interaction‐Feature Enhanced Multiuser Model Learning for a Home Environment Using Ambient Sensors

Activity recognition (AR) is a key enabler for a context‐aware smart home since knowing what the residents’ current activities helps a smart home provide more desirable services. This is why AR is often used in assistive technologies for cognitively impaired people to evaluate their abilities to undertake activities of daily living. In a real‐life scenario, multiple‐resident AR has been considered as a very challenging problem, primarily due to the complexity of data association. In addition, most prior research has not considered the potential interpersonal interactions among residents to simplify complexity, especially in an environment monitored by ambient sensors. In this study, we propose two types of multiuser activity models, both of which are derived from an interaction‐feature enhanced multiuser model learning framework. These two models consider interpersonal interactions and data association for multiuser AR using ambient sensors. We then compare their performance with the other two baseline models with or without consideration of data association and interpersonal interactions. The experimental results show that the derived models outperform other baseline classifiers. Therefore, the proposed approach can increase the opportunities for providing context‐aware services for a multiresident smart home.     

免费WiFi随身带

正对于经常出差的朋友来说,配有无线WiFi的酒店还是甚少,而身边的手机、平板电脑等移动设备却都需要WiFi网络的支持,那么用一台随身携带的笔记本电脑组建小型WiFi无线网络就显得很是重要了。现代生活最离不开的是什么?有人说是"手机",有人说是"电脑"……没错,都对,但是我们始终离不开的却是"网络"——互联网。网络已经成为了我们生活中,甚至是生命中的一部分,现代社会突然没有了网络,估计没有人知道,将会发生什么,世界末日?     

Mesoporous silica with short-range MFI structure

A new type of mesoporous silica has been prepared which showed 780 m²/g of BET surface area and 0.6 ml/g of primary mesopores narrowly distributed around 4.2 nm. More importantly however, is that it showed short-range zeolite crystallinity as demonstrated by FTIR and XRD analysis, and hydrophobicity as demonstrated by water and n-hexane adsorption.

This material was synthesized via a dual-template, three-step hydrothermal–flocculation–steaming synthesis procedure developed by us recently. Briefly, MFI nanoprecursors (NPs) were first prepared by a low-temperature hydrothermal step using TPAOH as template for zeolite structure, and then flocculated using a surfactant that served as the template for the mesopores. The collected NPs are mesoporous silica exhibiting short-range MFI domains when directly calcined. However, the steaming step promoted the crystallization of the NPs and created uniform mesopores. It was found that almost every detail in these procedures affected the properties of the final product. The most important variables, however, were identified as the duration the flocculants were kept in contact with the liquid phase, and the humidity under which the steaming was conducted. By properly adjusting the procedures, the said mesoporous silica, as well as nanocrystals having high external surface area, could be produced at will.     

Insolubilization of sodium chondroitin sulfate by forming a semi‐interpenetrating polymer network with acrylic acid: A potential carrier for colon‐specific drug delivery

To reduce the highly hydrophilic property of chondroitin sulfate (ChS), a semi‐interpenetrating polymer network (semi‐IPN) of chondroitin sulfate/polyacrylic acid (PAA) was prepared as a drug carrier by crosslinking acrylic acid with diethyleneglycol diacrylate. The swelling properties of the semi‐IPNs with different concentrations of crosslinking agent were correlated. The moisture sorption profiles were evaluated using differential thermal analysis. Ketoprofen was used as a drug probe to evaluate the performance of the drug released from the semi‐IPN matrices. The prepared semi‐IPNs demonstrated significant swelling reduction properties with both gastric and intestinal fluids compared with those of both the pure ChS and the ChSAA blend without the crosslinking agent. The amount of accumulated drug released from the semi‐IPNs was less than 30 wt % at pH 1.2 and up to 80 wt % at pH 7.4. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 114–122, 2002     

The effect of platinum and silver deposits in the photocatalytic oxidation of resorcinol

The effects of platinum (Pt) and silver (Ag) metallisation in the photocatalytic oxidation of resorcinol at pH 3 ± 0.5 have been investigated. The photocatalytic degradation of resorcinol was significantly improved by Pt/TiO₂, while the presence of Ag/TiO₂ enhanced the initial photocatalytic degradation rate of resorcinol slightly. Likewise, the photocatalytic mineralisation of resorcinol continued to be enhanced by Pt/TiO₂, but it was retarded when Ag/TiO₂ was used.

The function of Pt and Ag deposits on the surface of TiO₂ has been found to be markedly influenced by the interaction of resorcinol and its degradation products with the metal deposits. The presence of Pt or Ag on the surface of TiO₂ altered the distribution of degradation products of resorcinol as well as the production of photoactive species for the photocatalytic oxidation of resorcinol. The X-ray photoelectron spectroscopy (XPS), zeta potential and transmission electron microscopy (TEM) analyses have indicated that the contrasting effect of Pt and Ag deposits were governed by the oxidation states and the catalytic property of metal deposits. In addition to that, it has been found that the roles of metal deposits are specific and should not be generalised.     

Relation of swelling and Tg depression to the apparent free volume of a particle‐filled,epoxy‐based adhesive

The effect of hygrothermal aging on a particle‐filled, epoxy‐based adhesive was studied using a gravimetric sorption technique. This study has explored moisture sorption characteristics as well as the associated behaviors of swelling and the depression of the glass transition temperature (T_g). We observed that the diffusion of water in this adhesive has a non‐Fickian behavior, and the depression of T_g proceeds to a definite value that is independent of the final equilibrium water content of the system. Our observations suggest that water diffuses into the polymer in a dual‐sorption mode, in which water resides in two populations. In one population, water is considered to occupy apparent free volume of the adhesive, and the second population water infiltrates polymer structure and forms hydrogen‐bonded clusters. Our results show that hygrothermal aging temperature and swelling do not alter the apparent free volume of this adhesive. We conclude that the constant value of T_g depression at saturation implies that only water in the apparent free volume is responsible for the T_g depression, whereas the swelling proceeds through the formation of hydrogen bonds in the adhesive. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1436–1444, 2003     

Properties of polycarbonate/acrylonitrile-butadiene-styrene blends

To help make a good polymer blend by melt blending, the properties of polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) systems with various compositions have been investigated. As ABS is blended into PC to form a binary system, Brabender torque is reduced, a phenomenon that results in Improved processability of PC. With increasing ABS content, the mechanical properties of the blends such as tensile strength, modulus, hardness, and shrinkage decrease. However, with the variation of composition, Izod impact strength shows a maximum, while elongation at break exhibits a minimum. These phenomena are discussed with dynamic viscoelasticities and scanning electron microscopic morphological results. The value of ΔT_g(T_gβPC ? T_gβABS) is at its smallest when the ratio of PC to ABS is 90:10, However, the value rises with an increase in ABS because the butadiene content of the ABS hinders compatibility in the binary system. At the 90:10 composition, the damping height is optimal. In addition, the dispersed phase of the ABS is most ideal, absorbing the impact force and showing high impact strength. Composition ratios other than 90:10 present high damping as well as undesirable phase separation because of poor adhesion between two phases. As a result, the mechanical properties are reduced.