Microwave heating of carbon-based solid materials

As a part of the electromagnetic spectrum, microwaves heat materials fast and efficiently via direct energy transfer, while conventional heating methods rely on conduction and convection. To date, the use of microwave heating in the research of carbon-based materials has been mainly limited to liquid solutions. However, more rapid and efficient heating is possible in electron-rich solid materials, because the target materials absorb the energy of microwaves effectively and exclusively. Carbon-based solid materials are suitable for microwave-heating due to the delocalized pi electrons from sp2-hybridized carbon networks. In this perspective review, research on the microwave heating of carbon-based solid materials is extensively investigated. This review includes basic theories of microwave heating, and applications in carbon nanotubes, graphite and other carbon-based materials. Finally, priority issues are discussed for the advanced use of microwave heating, which have been poorly understood so far: heating mechanism, temperature control, and penetration depth.X1126Ysciescopu

Hybrid Simulation Safety: Limbos and Zero Crossings

Physical systems can be naturally modeled by combining continuous and discrete models. Such hybrid models may simplify the modeling task of complex system, as well as increase simulation performance. Moreover, modern simulation engines can often efficiently generate simulation traces, but how do we know that the simulation results are correct? If we detect an error, is the error in the model or in the simulation itself? This paper discusses the problem of simulation safety, with the focus on hybrid modeling and simulation. In particular, two key aspects are studied: safe zero-crossing detection and deterministic hybrid event handling. The problems and solutions are discussed and partially implemented in Modelica and Ptolemy II

Glycodelin suppresses endometrial cell migration and invasion but stimulates spheroid attachment

Glycodelin contains four isoforms with diverse biological functions. Glycodelin-A is potentially a diagnostic marker for cancer patients and receptivity marker of the secretory endometrium. Yet, direct evidence for the role of glycodelin in the regulation of endometrial epithelial cell migration, invasion and attachment of trophoblastic spheroids (blastocyst surrogate) is lacking. In this study, the human glycodelin gene was stably transfected into human endometrial (HEC1-B) cells. Forced expression of glycodelin in HEC1-B cells did not affect cell proliferation, cell viability or cell-cycle progression, but significantly reduced migration and invasion of the stably transfected cells (both P < 0.05). The migration rate returned to normal levels when the glycodelin-forced-expressing HEC1-B cells were treated with glycodelin RNAi. Furthermore, forced expression of glycodelin in HEC1-B cells significantly increased the attachment of trophoblastic spheroids onto the endometrial epithelial cells (P < 0.05). In summary, glycodelin suppressed endometrial cell migration and invasion but enhanced spheroid attachment. © 2012, Reproductive Healthcare Ltd.postprin

The Hong Kong Telephone Directory Enquiry System

Concerns the design and performance of the telephone directory enquiry system that has been newly adopted in Hong Kong. This system maintains three million telephone records and supports over 40,000 enquiries per hour at the peak. In Hong Kong society, the uses of English and Chinese (in particular, Cantonese) has been blending in a thrust of exciting language culture, giving rise to a variety of telephone enquires that traditional B-tree or hashing-based telephone directory enquiry systems fail to handle. The efficiency and flexibility achieved by the new system stem from hosting all indexing data structures in the main memory; these data structures occupy about half a giga-byte and would have been considered too expensive to be placed in main memory in the past.published_or_final_versio

Percutaneous transhepatic cholangioscopy (PTCS) in management of biliary tract stones: preliminary experience in Tung Wah Hospital

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Zaremba problem with degenerate weights

We establish Zaremba problem for Laplacian and $p$-Laplacian with degenerate weights when the Dirichlet condition is only imposed in a set of positive weighted capacity. We prove weighted Sobolev-Poincar\'{e} inequality with sharp scaling-invariant constants involving weighted capacity. Then we show higher integrability of the gradient of the solution (Meyers estimate) with minimal conditions on the part of the boundary where the Dirichlet condition is assumed. Our results are new both for the linear $p=2$ and nonlinear case and include problems with the weight not only as a measure but also as a multiplier of the gradient of the solution

Mathematical Model Identification of Self-Excited Systems Using Experimental Bifurcation Analysis Data

Self-excited vibrations can be found in many engineering applications such as flutter of aerofoils, stick-slip vibrations in drill strings, and wheel shimmy. These self-excited vibrations are generally unwanted since they can cause serious damage to the system. To avoid such phenomena, an accurate mathematical model of the system is crucial. Self-excited systems are typically modelled as dynamical systems with Hopf bifurcations. The identification of such non-linear dynamical system from data is much more challenging compared to linear systems. In this research, we propose two different mathematical model identification methods for self-excited systems that use experimental bifurcation analysis data. The first method considers an empirical mathematical model whose coefficients are identified to fit the measured bifurcation diagram. The second approach considers a fundamental Hopf normal form model and learns a data-driven coordinate transformation mapping the normal form state-space to physical coordinates. The approaches developed are applied to bifurcation data collected on a two degree-of-freedom flutter rig and the two methods show promising results. The advantages and disadvantages of the methods are discussed

Simplified Dynamic Assessment for Reinforced-Concrete Structures Subject to Column Removal Scenarios

A simple yet effective method for dynamic assessment of building structures subject to a sudden column removal is presented. An equivalent single-degree-of-freedom (SDOF) dynamic model to predict the realistic dynamic response of the structure after column removal is proposed. This model considers nonzero initial conditions that are likely to occur under blast loading and structural damping, which can significantly affect the dynamic performance under large deformations. Based on the proposed method, dynamic response of a structure subject to a specific dynamic loading released from column removal is analytically solved. Four sets of physical tests of structures subject to column removal, including quasi-static tests and the corresponding multiple free-fall dynamic tests, are employed to verify the proposed assessment method. In addition, the classical pseudostatic assessment is conducted for the test series and compared with the present method. Results obtained from the verification study demonstrate the accuracy and effectiveness of the proposed simplified dynamic assessment. In addition, the proposed equivalent SDOF method is simple and can be easily implemented with a spreadsheet by practicing engineers. This advantage allows the proposed method to be employed as a routine design procedure for predicting the dynamic performance of structures subject to column removal

Identifying Buckling Resistance of Reinforced Concrete Columns during Inelastic Deformation

A simple solution method to identify buckling resistance of reinforced concrete (RC) columns during inelastic deformation is presented. Unlike conventional buckling solution methods, this proposed method predicts inelastic buckling loads of RC columns by directly solving the equilibrium differential equation under buckling. The method considers specific deflection configuration, end restraint conditions and inelastic material properties of the deformed column. In order to evaluate the reliability and accuracy of the proposed method, the results obtained from the purposed method are compared with the test results of eccentrically loaded RC columns. In addition, by using the proposed solution procedure, a parametric study is conducted to investigate the effects of critical RC column design parameters on column buckling behavior and resistance, including slenderness ratio, concrete strength, as well as longitudinal reinforcement and stirrup ratios. The results of the parametric study show that the proposed method is rational and can be adopted to effectively identify buckling resistance of RC columns subjected to inelastic damage, especially when load redistributions have occurred in the structure during progressive collapse

Effects of progressive backward body weight supported treadmill training on gait ability in chronic stroke patients: A randomized controlled trial

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