A Magnetorheological Damper with Embedded Piezoelectric Force Sensor: Experiment and Modeling

This chapter describes configuration, fabrication, calibration and performance tests of the devised self-sensing MR damper firstly. Then, a black-box identification approach for modeling the forward and inverse dynamics of the self-sensing MR damper is presented, which is developed with the synthesis of NARX model and neural network within a Bayesian inference framework to have the ability of enhancing generalization.Department of Civil and Environmental Engineerin

INVESTIGATION OF FOULING PROCESS FOR CONVECTIVE HEAT TRANSFER IN AN ANNULAR DUCT

Experimental and theoretical study is summarized of fouling process on heat transfer surface. An automatic monitoring system was set up to determine impact of fouling. Experiments were performed with artificial hard water as a working fluid at different conditions. Some important parameters including water temperature, wall temperature, flow velocity, water hardness and alkalinity were testified to make sure their influences on the fouling process on heat transfer surfaces. The ranges of water temperature, wall temperature, flow velocity and water hardness are between 20～50℃, 50～75℃, 0.5～2.0m/s, 200 ～ 1000mg/L (as CaCO3), respectively. All the experimental data were recorded continuously and the fouling resistances were calculated accordingly. Furthermore, an analysis was conducted to understand mechanism of fouling on heat transfer surface according a new physical model of fouling process. Good agreements can be observed between calculated results and experimental data

A computed-based model for the alkali concentrations in pore solution of hydrating Portland cement paste

A computed-based model for the alkali concentrations in pore solution of hydrating Portland cement paste is proposed. Experimental data reported in different literatures with thirteen different recipes are analyzed. A 3-D computer-based cement hydration model CEMHYD3D is used to simulate the hydration of these pastes. The models predictions are used as inputs for the alkali partition theory, which is used to derive the alkali binding capacity of C-S-H in hydrating Portland cement paste. A linear relation between the amount of bound-alkali Na+ in C-S-H and its concentration in the pore solution is found, whilst a non-linear relation should be employed for the amount of bound-alkali K+ in C-S-H. New methods for predicting the alkali concentrations in the pore solution of hydrating Portland cement pastes are proposed based on the computer model CEMHYD3D, which is also validated with experimental results

INVESTIGATION OF FOULING PROCESS FOR CONVECTIVE HEAT TRANSFER IN AN ANNULAR DUCT

Experimental and theoretical study is summarized of fouling process on heat transfer surface. An automatic monitoring system was set up to determine impact of fouling. Experiments were performed with artificial hard water as a working fluid at different conditions. Some important parameters including water temperature, wall temperature, flow velocity, water hardness and alkalinity were testified to make sure their influences on the fouling process on heat transfer surfaces. The ranges of water temperature, wall temperature, flow velocity and water hardness are between 20～50℃, 50～75℃, 0.5～2.0m/s, 200 ～ 1000mg/L (as CaCO3), respectively. All the experimental data were recorded continuously and the fouling resistances were calculated accordingly. Furthermore, an analysis was conducted to understand mechanism of fouling on heat transfer surface according a new physical model of fouling process. Good agreements can be observed between calculated results and experimental data

Second harmonic generation and birefringence of some ternary pnictide semiconductors

A first-principles study of the birefringence and the frequency dependent second harmonic generation (SHG) coefficients of the ternary pnictide semiconductors with formula ABC$_2$ (A = Zn, Cd; B = Si, Ge; C = As, P) with the chalcopyrite structures was carried out. We show that a simple empirical observation that a smaller value of the gap is correlated with larger value of SHG is qualitatively true. However, simple inverse power scaling laws between gaps and SHG were not found. Instead, the real value of the nonlinear response is a result of a very delicate balance between different intraband and interband terms.Comment: 13 pages, 12 figure

QuizMap: Open social student modeling and adaptive navigation support with TreeMaps

In this paper, we present a novel approach to integrate social adaptive navigation support for self-assessment questions with an open student model using QuizMap, a TreeMap-based interface. By exposing student model in contrast to student peers and the whole class, QuizMap attempts to provide social guidance and increase student performance. The paper explains the nature of the QuizMap approach and its implementation in the context of self-assessment questions for Java programming. It also presents the design of a semester-long classroom study that we ran to evaluate QuizMap and reports the evaluation results. © 2011 Springer-Verlag Berlin Heidelberg

Rotational symmetry of self-similar solutions to the Ricci flow

Let (M,g) be a three-dimensional steady gradient Ricci soliton which is non-flat and \kappa-noncollapsed. We prove that (M,g) is isometric to the Bryant soliton up to scaling. This solves a problem mentioned in Perelman's first paper.Comment: Final version, to appear in Invent. Mat

Growth evolution and formation mechanism of η ′-Cu 6 Sn 5 whiskers on η -Cu 6 Sn 5 intermetallics during room-temperature ageing

Abstract(#br)The phase-transformation-induced damage of Cu 6 Sn 5 is an emerging reliability issue in the manufacturing of 3D ICs. Although the retarded phase transformation from η -Cu 6 Sn 5 to η ′-Cu 6 Sn 5 at room temperature can produce a large expansion in volume, how the transformation stress threatens the joint reliability during usage is poorly understood. In this paper, the evolution characteristics of quenched η -Cu 6 Sn 5 bumps were observed during ageing at 25 °C for 1–40 d Due to the retarded phase transformation, η ′-Cu 6 Sn 5 whiskers spontaneously nucleated and grew on the surfaces of η -Cu 6 Sn 5 bumps. The orientation relationship between the two phases favourable for whisker growth was confirmed, and two necessary conditions for whisker formation were discussed. In addition, the potential harmfulness of whisker growth was analysed. The study will help expose the phase-transformation-induced damage of Cu 6 Sn 5 during room-temperature ageing and may reduce the failure risk of entire Cu 6 Sn 5 intermetallic joints in future large-scale applications of 3D ICs