Experimental study of acoustic characteristics of expansion chamber with mean flows

For the measurement of transmission loss of the silencers which have mean flow, the noise levels of signals depicted by microphone usually prohibit accurate measurements of the transmission loss. To overcome this difficulty, static pressure compensation technique has been developed to increase the dynamic range of the microphones, resulting accurate measurement of transmission loss in the presence of high noise level. Series of experiments to investigate the acoustic characteristics of expansion chamber with mean flow has been performed using the pressure compensated microphones. Results demonstrate: (1) frequency shift due to the presence of mean flow, (2) effect of length, diameter, offset length and twisting angles to the transmission loss of expansion chamber with and without mean flow (up to 50m/sec), (3) relation between the proposed parameter ‘aspect ratio’ and number of peaks of transmission loss in low frequency region.     

Improvement of the steering feel of an electric power steering system by torque map modification

This paper discusses a de motor equipped electric power steering (EPS) system and demonstrates its advantages over a typical hydraulic power steering (HPS) system The tire-road interaction torque at the steering tires is calculated using the 2 d o f bicycle model, in other words by using a single-track model, which was verified with the J-turn test of a real vehicle Because the detail parameters of a steering system are not easily acquired, a simple system is modeled here In previous EPS systems, the assisting torque for the measured driving torque is developed as a boost curve similar to that of the HPS system To improve steering stiffness and return-ability of the steering system, a third-order polynomial as a torque map is introduced and modified within the preferred driving torques researched by Bertollini Using the torque map modification sufficiently improves the EPS system     

Phase field simulations of coupled microstructure solidification problems via the strong form particle difference method

This paper presents the development of a strong form-based collocation method called the particle difference method (PDM), capable of predicting the spatiotemporal evolution of polycrystalline material solidification through coupling of multi-phase and temperature fields. Cross coupled phase field evolution and heat transfer equations are discretized via the PDM to obtain the interface kinematics of polycrystalline boundary during solidification. A distinct feature of the PDM is its ability to represent derivative operators via a moving least-square approximation of the Taylor expansion through point-wise computations at collocation points. The method discretizes directly the strong forms using the pre-computed derivative operators at each collocation point and elegantly overcomes the topological difficulty in modeling intricate moving interfaces. To verify the efficacy of the PDM, numerical results are compared with those obtained from the conventional finite difference method for uniform and irregular distributions of the collocation points. The scalability of the parallelized PDM is tested by measuring its efficiency with increasing the number of processors. We also provide a solidification simulation with two ellipsoidal inclusions to demonstrate the capability of the PDM in complex moving interface problems with high curvature.     

Formal or informal human collaboration approach to maritime safety using FRAM

Cognition, Technology & Work - It has been argued that human and organizational factors are critical for accident analysis and safety management. The maritime domain represents a...     

Encouraging collaboration and building Community in Online Asynchronous Professional Development: designing for social capital

International Journal of Computer-Supported Collaborative Learning - This research investigates a design and development approach to improving science teachers’ access to effective...     

Semi-automatic Knob System for Assisting Flexible Endoscope Steering

International Journal of Control, Automation and Systems - In this paper, a semi-automatic knob system for assisting control of flexible endoscope is introduced. For conventional flexible...     

On the orthogonal similarity transformation (OST)-based sensitivity analysis method for robust topology optimization under loading uncertainty: a mathematical proof and its extension

The main purpose of this work is to provide a mathematical proof of our previously proposed orthogonal similarity transformation (OST)-based sensitivity analysis method (Zhao et al. Struct Multidisc Optim 50(3):517–522 2014a, Comput Methods Appl Mech Engrg 273:204–218 c); the proof is designed to show the method’s computational effectiveness. Theoretical study of computational efficiency for both robust topology optimization and robust concurrent topology optimization problems shows the necessity of the OST-based sensitivity analysis method for practical problems. Numerical studies were conducted to demonstrate the computational accuracy of the OST-based sensitivity analysis method and its efficiency over the conventional method. The research leads us to conclude that the OST-based sensitivity analysis method can bring considerable computational savings when used for large-scale robust topology optimization problems, as well as robust concurrent topology optimization problems.