Thermomechanical formation and recovery of nanoindents in a shape memory polymer studied using a heated tip

This paper investigates the thermomechanical formation and recovery of nanometer-scale indents in a shape memory polymer (SMP), studied using a heated atomic force microscope (AFM) tip and hot-stage atomic force microscopy. The material tested is a tert-butyl acrylate (tBA)-based polymer, which has a glass transition temperature of 60 degrees C. The AFM tip forms indents in the polymer in the temperature range 25-250 degrees C. The shape recovery of the indents is studied while the polymer is heated up to 100 degrees C. The temperature required for complete annealing of the indents depends upon the indentation formation conditions, with higher temperature formation corresponding to higher temperature recovery.     

Minimizing L max for large-scale,job-shop scheduling problems

The academic literature in 2000 presented a procedure for solving the job-shop-scheduling problem of minimizing L _max. The iterative-adaptive simulation-based procedure is shown here to perform well on large-scale problems. However, there is potential for improvement in closing the gap between best-known solutions and the lower bound. In the present paper, a simulated annealing post-processing procedure is presented and evaluated on large-scale problems. A new neighbourhood structure for local searches in the job-shop scheduling problem is developed. The procedure is also evaluated using benchmark problems and new upper bounds are established.     

Dynamics of a viscous thread on a non-planar substrate

We derive a general reduced model for the flow of a slender thread of viscous fluid on a grooved substrate. Specific choices of the substrate topography allow further analytic progress to be made, and we subsequently focus on a convection–diffusion equation governing the evolution of viscous liquid in a wedge geometry. The model equation that arises also appears in the context of foam drainage, and we take the opportunity to review and compare the results from both applications. After summarising the constant mass results, we introduce a time-dependent fluid influx at one end of the wedge. The analytical results are supported by numerical computations.     

Decoherence of motional states of trapped ions

Abstract

We have studied the decoherence of motional-state superpositions of single trapped ions caused by their coupling to fluctuating fields. We illustrate these studies by showing how Schrödinger-cat state superpositions decohere in the presence of purposely-applied uniform stochastic electric fields and we compare these results to the decoherence caused by ambient fields in the experiments.     

Rare earth element cerium substituted Ca–Si–Mg system bioceramics: From mechanism to mechanical and degradation properties

Cerium (Ce)-substituted diopsides (CaMgSi₂O₆) with enhanced mechanical strength and bioactivity were fabricated by precipitation method, followed by annealing at 1000 °C for 4 h. The mineralogical, morphological, in vitro biomineralization, degradation, and mechanical properties were investigated in order to assess the factors and mechanisms affecting the resultant properties. The X-ray diffractometer results showed that the onset of substitutional solid solubility in 0.25 mol Ce would result in new phase formation (cerium dioxide [CeO₂], and magnesium silicate [MgSiO₃]) further causing lattice instability. With increasing Ce dopant levels to 1.00 mol, the initial CaMgSi₂O₆ phase was completely replaced by new phases. The field-emission scanning electron microscopy results indicated that the 0.25 mol Ce had the best biomineralization performance in vitro, while less hydroxyapatite precipitates were found with further increasing Ce dopant levels, suggesting the new phases led to the hindrance of precipitates. The weight loss values indicated that the high dissolution rate of ions in the matrix was observed in the pure sample, while the high readsorption rate of ions in the simulated body fluid (SBF) occurred with increasing Ce dopant levels. The pH value and the inductively coupled plasma-mass spectrometer results suggested that the release of Ca and Mg ions controlled the pH value. The mechanical strength of matrices before SBF immersion was related to the phase transformation, the elastic modulus of CeO₂ and CaMgSi₂O₆, and the release of Mg ions, while the mechanical strength of matrices after SBF immersion was dominated by the structure of matrices.     

Big label: categorizing the Web efficiently and accurately

Searching on the Web has never been an easy task. Even if semantic information is successfully inferred from a user query, how can we benefit from it? The most popular remedy today is to categorize the Web in advance. By gathering similar Web resources into a group, the search performance should increase even though search engines still have little idea about the semantics part. To categorize a set of Web resources according to meta-information associated with them, at first, one has to analyze the relationships between meta-information and Web resources. However, the result will be severely affected by the ambiguous nature of the Web. As a result, the goal of this research is to propose a new labeling method to enhance both the efficiency and accuracy of Web resources categorization.     

An experimental model of Chinese textual database

Abstract

A textual database deals with retrieval and manipulation of documents. It allows a user to search on‐line complete documents or parts of documents rather than attributes of documents. Resembling a formatted database which uses a data model as its underlying structure, a textual database has to base its development upon a document model. In this paper, a document model, called the ECHO model, is proposed. The ECHO model provides a document representation, called the ECHO structure, for expressing documents and operations on the representation that serve to express queries and manipulations on documents. It has the ability to provide multiple document structures for a document, a flexible search unit for retrieving textual information, and a subrange search on a textual database. In addition, the ECHO structure is relatively easy to maintain. An architecture of a textual database based on the ECHO model is also proposed. In order to improve the query performance, a refined character inversion method, called ARCIM, is proposed as the text‐access method of the Chinese textual database. The ARCIM can retrieve texts faster than a simple inversion method and requires less space overhead.     

Two MILP models for the N × M SDST flowshop sequencing problem

This paper presents the derivation and evaluation of two new MILP models for the SDST flowshop sequencing problem. The first model, TS1, was derived directly from the assignment-problem-based MILP model for the regular flowshop that Stafford modified from the original Wagner three-machine all-integer model. The second model, TS2, combined the properties of model TS1 with the looser constraints approach of Srikar and Ghosh, as modified by Stafford and Tseng (model SG*). Three experiments were used to compare both new models to the SG* model. Both new models were found to use significantly less computation time than the SG* model, especially for problem sizes of 6 or more jobs and 5 or more machines. The TS1 model used significantly less computation time than the TS2 model, making it the current best MILP model in the SDST flowshop literature.     

Group-Based Authentication and Key Agreement

This paper presents an authentication and key agreement protocol to streamline communication activities for a group of mobile stations (MSs) roaming from the same home network (HN) to a serving network (SN). In such a roaming scenario, conventional schemes require the SN to interact with the HN for authenticating respective MSs, at the cost of repeated message exchanges and communication delay. Instead, in our design, when the first MS of a group visits, the SN performs full authentication with the concerned HN and thereby obtains authentication information for the MS and other members. Thus when any other MS of the same group visits, the SN can authenticate locally without subsequent involvement of the HN, so as to simplify protocol operations. We will show that our scheme does not trade performance for security and robustness to the extent that security requirements are unduly weakened. Both qualitative and quantitative discussions indicate that our proposed scheme lends itself to pragmatic settings.