CAWR: Buffer Replacement with Channel-Aware Write Reordering Mechanism for SSDs

Ronghui Wang,Zhiguang Chen,Nong Xiao,Minxuan Zhang,Weihua Dong 한국전자통신연구원 2015 ETRI Journal Vol.37 No.1

A typical solid-state drive contains several independent channels that can be operated in parallel. To exploit this channel-level parallelism, a variety of works proposed to split consecutive write sequences into small segments and schedule them to different channels. This scheme exploits the parallelism but breaks the spatial locality of write traffic; thus, it is able to significantly degrade the efficiency of garbage collection. This paper proposes a channel-aware write reordering (CAWR) mechanism to schedule write requests to different channels more intelligently. The novel mechanism encapsulates correlated pages into a cluster beforehand. All pages belonging to a cluster are scheduled to the same channels to exploit spatial locality, while different clusters are scheduled to different channels to exploit the parallelism. As CAWR covers both garbage collection and I/O performance, it outperforms existing schemes significantly. Trace-driven simulation results demonstrate that the CAWR mechanism reduces the average response time by 26% on average and decreases the valid page copies by 10% on average, while achieving a similar hit ratio to that of existing mechanisms.

Nonlinear Vibration of a Stiffened Plate Considering the Existence of Initial Stresses

Tian-Qi Wang,Ronghui Wang,Niu-Jing Ma 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.5

This paper presents a study on the nonlinear dynamic behavior of a stiffened plate with the existence of initial stresses. A stiffened plate is assumed to be composed of a plate and some stiffeners, which are treated separately. The plate is analyzed based on Thin Plate Theory, while the stiffeners are considered as geometrically nonlinear Euler-Bernoulli beams. The equations of both kinetic energies and strain energies of the plate and stiffeners are established. After that, the dynamic equilibrium equations for the stiffened plate are derived according to Lagrange equation. The nonlinear frequency for single-mode result is obtained through Elliptic function, and the accuracy of the analytical solution is verified through comparison with Ansys finite element method. In addition, homotopy analysis method is used to solve 3:1 internal resonance of the stiffened plate. With parametric analysis being conducted, the investigation on how initial stresses influence the nonlinear dynamic properties is carried out. Some useful nonlinear dynamic properties and conclusions are obtained, and thees can provide references for engineering application.

Strongly nonlinear free vibration of four edges simply supported stiffened plates with geometric imperfections

Zhaoting Chen,Ronghui Wang,Li Cheng,Chunguang Dong 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.8

This article investigated the strongly nonlinear free vibration of four edges simply supported stiffened plates with geometric imperfections. The von Karman nonlinear strain-displacement relationships are applied. The nonlinear vibration of stiffened plate is reduced to a one-degree-of-freedom nonlinear system by assuming mode shapes. The Multiple scales Lindstedt-Poincare method (MSLP) and Modified Lindstedt-Poincare method (MLP) are used to solve the governing equations of vibration. Numerical examples for stiffened plates with different initial geometric imperfections are presented in order to discuss the influences to the strongly nonlinear free vibration of the stiffened plate. The results showed that: the frequency ratio reduced as the initial geometric imperfections of plate increased, which showed that the increase of the initial geometric imperfections of plate can lead to the decrease of nonlinear effect; by comparing the results calculated by MSLP method, using MS method to study strongly nonlinear vibration can lead to serious mistakes.

3D implementation of push-out test in ABAQUS using the phase-field method

Xianbin Yu,Ronghui Wang,Chunguang Dong,Jianyi Ji,Xiaoxia Zhen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.4

The phase-field method (PFM) localizes the damaged and broken material in concrete with a phase-field order parameter d, successfully avoiding the description of nonsmooth crack surfaces, as well as the pre-setting and tracking of complex crack extension paths. However, most works have focused on 2D and simple 3D problems of non-reinforced concrete due to the high computational cost. A 3D PFM is implemented in the commercial finite element code ABAQUS to model damage and quasi-brittle fractures in composite beam concretes. The damage problem is implemented in the user subroutines UMAT and HETVAL on account of the similarity between the evolution law of the order parameter and the heat transfer law. In addition, a FORTRAN file is used to define the relationships among the material properties. Through this approach, modeling, computational task submission, and post-processing are completed in the GUI of ABAQUS, and the internal nonlinear algorithms are adopted directly. The accuracy of the modeling method is verified by comparing with two classical experimental data in the literature, and the maximum load data and load-displacement curve are well fitted. Moreover, a 3D numerical model for the push-out test of the composite beam is developed. Simulation results are consistent with the test results, such as the trend of the loaddisplacement curve, the damage pattern of the concrete, and the stress condition of the shear bolts. The parametric analysis shows that the compressive and tensile strengths of the shear bonds can significantly affect the load bearing capacity of composite beams, whereas the material parameters of concrete have a limited influence, consistent with the previous experience. The PFM has proven its ability to handle complex quasi-brittle fracture of concrete, and the present work can provide a reference for modeling concrete cracks in engineering structures.

Lane Detection Algorithm for Night-time Digital Image Based on Distribution Feature of Boundary Pixels

Feng You,Ronghui Zhang,Lingshu Zhong,Haiwei Wang,Jianmin Xu 한국광학회 2013 Current Optics and Photonics Vol.17 No.2

This paper presents a novel algorithm for nighttime detection of the lane markers painted on a road at night. First of all, the proposed algorithm uses neighborhood average filtering, 8-directional Sobel operator and thresholding segmentation based on OTSU’s to handle raw lane images taken from a digital CCD camera. Secondly, combining intensity map and gradient map, we analyze the distribution features of pixels on boundaries of lanes in the nighttime and construct 4 feature sets for these points, which are helpful to supply with sufficient data related to lane boundaries to detect lane markers much more robustly. Then, the searching method in multiple directions- horizontal, vertical and diagonal directions, is conducted to eliminate the noise points on lane boundaries. Adapted Hough transformation is utilized to obtain the feature parameters related to the lane edge. The proposed algorithm can not only significantly improve detection performance for the lane marker, but it requires less computational power. Finally, the algorithm is proved to be reliable and robust in lane detection in a nighttime scenario.

Hysteretic behavior of multi-layered beams with Coulomb friction interface law

Yonglin Zhao,Ronghui Wang,Zhuojie Zhang,Xiaoxia Zhen,Lu Wang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8

This paper presents a novel recursive algorithm to investigate the slip process of multi-layered laminated beams with Coulomb friction interface law under Euler-Bernoulli beam assumption. Based on the incremental superposition method, the periodic mechanical behavior of a cantilever multi-layered beam under quasi-static reciprocating loading is presented. Particularly, the force-deformation hysteresis loop of the beam is drawn to investigate the changing process of its stiffness. The changing process of the potential energy and the frictional energy dissipation of the beam is calculated analytically, then the results suggest that multi-layered beams with Coulomb friction interface law exhibit both energy dissipation capacity and energy storage property. A numerical example employing zero-thickness nonlinear spring elements which can satisfy the Coulomb friction interface law is implemented and its accuracy is verified against the analytical solution by increasing the density of the zero-thickness elements.

Adaptive finite element analysis of steel girder deck pavement

Wenhuo Sun,Lixiong Gu,Ronghui Wang,Tiedong Qi 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.2

This paper shows a more exact and practical finite element model of the steel girder deck pavement. Based on Mindlin thick plate theory, a 12-node solid thick plate element was constituted to analyze the pavement. The computation result was compared with that by traditional 4-node and 8-node thick plate finite element, and is satisfactory. A combined plate beam element method is presented to investigate the stiffened plate. A 6-node solid thin plate element was constituted to analyze the top plate based on Kirchhoff thin plate theory. The stiffeners acting as the vertical supporting function mainly are taken as Euler beam elements. A method of using the linear interpolation to realize the longitudinal displacement and the cubic Hermite interpolation to the vertical displacement is presented to analyze the stiffeners. In addition, it is essential to consider the displacement coordination between the top plate and stiffeners. A node-to-node contact scheme, which is applicable for three-dimensional contact analyses involving large deformations, was used to treat the contact problem between pavement and stiffened plate by Lagrange multiplier methods.

Effects of Impact Loads on Local Dynamic Behavior of Orthotropic Steel Bridge Decks

Niu-Jing Ma,Ronghui Wang 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.1

To investigate the local dynamic behavior of orthotropic steel bridge decks under impact loads, this paper proposed a type of combined plate-beam element for analysis of trapezoidal stiff ened plate and a type of 8-nodes solid-plate element for analysis of pavement. Besides, vehicle wheel loads are supposed to be triangular loads for convenience. Then, a model experiment was conducted to verify the accuracy of the proposed approach. Finally, River-sea-through channel of Hong Kong–Zhuhai– Macao Bridge is taken as an engineering case for computation analysis. The results are compared with those from FE software ANSYS. It shows that: fi rst, the proposed approach is both accurate and effi cient; second, bridge deck pavement has the eff ect of both self-weight and rigidity, which requires the bridge deck pavement be considered when analyzing the mechanical properties of bridge deck structure.

A dynamic finite element method for the estimation of cable tension

Yonghui Huang,Quan Gan,Shiping Huang,Ronghui Wang 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.4

Cable supported structures have been widely used in civil engineering. Cable tension estimation has great importance in cable supported structures’ analysis, ranging from design to construction and from inspection to maintenance. Even though the Bernoulli-Euler beam element is commonly used in the traditional finite element method for calculation of frequency and cable tension estimation, many elements must be meshed to achieve accurate results, leading to expensive computation. To improve the accuracy and efficiency, a dynamic finite element method for estimation of cable tension is proposed. In this method, following the dynamic stiffness matrix method, frequency-dependent shape functions are adopted to derive the stiffness and mass matrices of an exact beam element that can be used for natural frequency calculation and cable tension estimation. An iterative algorithm is used for the exact beam element to determine both the exact natural frequencies and the cable tension. Illustrative examples show that, compared with the cable tension estimation method using the conventional beam element, the proposed method has a distinct advantage regarding the accuracy and the computational time.

AGV Motion Balance and Motion Regulation Under Complex Conditions

Yanming Quan,Ma Lei,Weizhao Chen,Ronghui Wang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.2

AGV cargo robot is widely used in flexible production line of intelligent factory. Different conditions for cargo instability occurs in different production line scenarios, different loading conditions and different movement states, which greatly affect the security and reliability of AGV cargo transport. In order to realize the acceleration limits of the buckling critical instability state under different loading and motion states, a multi-sensor sensing system was built on the AGV platform. The inertial measurement unit, pressure sensor and odometer were used to realize the cargo state’s real-time perception and AGV motion state. The pressure sensor and inertial measurement unit were used to measure the cargo gravity center position that affects the carry stability and neural network algorithm training was used to get accurate judgment of different motion states. The kinematic mechanical equilibrium model was established to analyze the relative equilibrium state of AGV and cargo under different motion states and to determine the cargo critical instability acceleration constraint conditions under different transport conditions of different goods. The test results show that the platform can obtain the cargo gravity center position and perceive the AGV motion state in real-time, feedback the acceleration constraint under the current motion state in real-time and regulate the AGV to realize the safe and stable delivery of the cargo at any time under the multi-sensor perception.