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.     

Dynamic adhesion characterization of cancer cells under blood flow-mimetic conditions: effects of cell shape and orientation on drag force

Cell adhesion to and detachment from the endothelium plays an essential role in numerous biological processes such as cancer cell metastasis, cell migration, and cell–cell communication. However, little is known about the effect of cell shape and orientation on the drag force leading to cell detachment. To further investigate these factors, we cultured cancer cells in a microfluidic channel, and recorded the shape and orientation of the cells under constant fluid flow rate. Results showed that cell morphology varied dynamically with respect to time. In particular, we discovered two distinct shapes of cells at the moment of detachment: the circular shape, and the elongated shape whose long axis is perpendicular to the flow. Based on the experimental observations, we designed and reconstructed two cellular solid models (a hemispherical model and an elongated model) to calculate the drag force using a finite-element method. The hemispherical model yielded much higher pressure drag force than that of the elongated models irrespective of orientation, though the total drag force of the hemispherical model was slightly lower. We also examined the effect of the orientation on the drag force using five different orientations to the flow. The cells of which the long axes were perpendicular to the flow exhibited larger pressure drag force than cells oriented in other directions, though the friction drag force was comparable. In summary, when cells detach from the surface, the fraction of the pressure force becomes larger, demonstrating the determinative role of cell adhesion and/or detachment. Significantly, our observation that two cancer cell subpopulations exist exhibiting different morphological dynamics and required drag forces for detachment implies redundant mechanisms for cancer cells to achieve the transition from the adherent type to the circulating type during metastasis.