Rapid and Flexible User-Defined Low-Level Hybridization for Metaheuristics Algorithm in Software Framework

The metaheuristics algorithm is increasingly important in solving many kinds of real-life optimization problems but the implementation involves programming difficulties. As a result, many researchers have relied on software framework to accelerate the development life cycle. However, the available software frameworks were mostly designed for rapid development rather than flexible programming. Therefore, in order to extend software functions, this approach involves modifying software libraries which requires the programmers to have in-depth understanding about the internal working structure of software and the programming language. Besides, it has restricted programmers for implementing flexible user-defined low-level hybridization. This paper presents the concepts and formal definition of metaheuristics and its low-level hybridization. In addition, the weaknesses of current programming approaches supported by available software frameworks for metaheuristics are discussed. Responding to the deficiencies, this paper introduces a rapid and flexible software framework with scripting language environment. This approach is more flexible for programmers to create a variety of user-defined low-level hybridization rather than bounded with built-in metaheuristics strategy in software libraries.

对冲式止回阀低流量关闭过程动态特性分析

为减小动力装置止回阀切换时的水击和阀头与阀座的撞击,提出了阀头与流体运动方向互逆的对冲式止回阀。将FLUENT的动网格技术引入到止回阀内部流场的模拟中,解决了阀门关闭时内部流场区域瞬时变化的问题。由牛顿运动第二定律的欧拉显式格式得出了阀门在关闭过程中的流量变化,阀头、阀座的受力变化和速度变化,通过以上参量判断阀头、阀座的工作状态,最后通过实验来验证理论分析的结果。模拟结果与实验表明,动网格技术能够较好地模拟阀门内部流场的变化,对冲式止回阀能够可靠地在小流量情况下关闭。

基于FLUENT的海洋内孤立波数值水槽模拟

基于FLUENT商业软件及其二次开发功能,在标准κ-ε湍流模型下,采用VOF方法追踪两层流体内界面,通过给定入口速度和水位的设置造波边界法,建立了可有效模拟弱非线性内孤立波的分层流数值水槽,并与仿物理的双板造波方法进行了比较。采用设置边界法所造的波形与理论值符合较好,这为数值分析内孤立波与海洋结构物相互作用问题提供了一条更加有效的途径。

Fully fluid-solid coupling dynamic model for seismic response of underground structures in saturated soils

The seismic response characteristics of underground structures in saturated soils are investigated.A fully fluid-solid coupling dynamic model is developed and implemented into ABAQUS with a user-defined element to simulate the dynamic behavior of saturated soils.The accuracy of the model is validated using a classic example in literature.The performance of the model is verified by its application on simulating the seismic response characteristics of a subway station built in saturated soils.The merits of the model are demonstrated by comparing the difference of the seismic response of an underground structure in saturated soils between using the fully coupling model and a single-phase medium model.The study finds that the fully coupling model developed herein can simulate the dynamic response characteristics of the underground structures in saturated soils with high accuracy.The seismic response of the underground structure tends to be underestimated by using the single-phase medium model compared with using the fully coupling model,which provides a weaker confining action to the underground structure.

Development and application of a multi-physics and multi-scale coupling program for lead-cooled fast reactor

In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and the NDK code is a neutron diffusion code.The coupling program framework adopts the"master-slave"mode,in which Fluent is the master program while NDK and KMC-sub are coupled internally and compiled into the dynamic link library(DLL)as slave codes.The domain decomposition method was adopted,in which the reactor core was simulated by NDK and KMC-sub,while the rest of the primary loop was simulated using Fluent.A simulation of the reactor shutdown process of M2LFR-1000 was carried out using the coupling program,and the code-to-code verification was performed with ATHLET,demonstrating a good agreement,with absolute deviation was smaller than 0.2%.The results show an obvious thermal stratification phenomenon during the shutdown process,which occurs 10 s after shutdown,and the change in thermal stratification phenomena is also captured by the coupling program.At the same time,the change in the neutron flux density distribution of the reactor was also obtained.

Finite element modeling of pavement responses based on stress-dependent properties of asphalt layer

In order to investigate the stress-dependent properties of hot-mix asphalt （HMA）,a dynamic modulus test was conducted on a group of AC-20 specimens at various stress states and loading frequencies,respectively.A user-defined material （UMAT ）subroutine incorporating stress-dependent constitutive model was developed and finite element （FE）simulation was utilized to confirm the validity of the UMAT.A three-dimensional （3D ）FE model for typical pavement structure was established,considering the HMA layer as a stress-dependent material and other layers as linear elastic materials.Periodic load was applied to the pavement model and the pavement responses were calculated,including dynamic modulus distributions,surface deflection,shear stress and tensile strain in the HMA layer,etc.Both test results and FE model predictions indicate that the dynamic modulus of asphalt concrete is sensitive to stress state and loading frequency.Using the nonlinear stress-dependent model results in greater predicted pavement responses compared with the linear elastic model.It is also found that the effects of stress-dependency on pavement responses become more significant as loading frequency decreases.

Confidence support vector domain description

To accelerate the training of support vector domain description （SVDD）, confidence support vector domain description （CSVDD） is proposed based on the observation that the description boundary is determined by a small subset of training data called support vectors. Namely, the number of training samples in the userdefined sphere is calculated and taken as the confidence measure, according to which the training samples are ranked in ascending order. Those former ranked ones are selected as the boundary targets for the SVDD training. Simulations on UCI data demonstrate the effectiveness and superiority of CSVDD： the number of training targets and the training time are reduced without any loss of accuracy.

The IRIS Development Platform and Proposed Object-Oriented Data Base

Various code development platforms, such as the ATHENA Framework [1] of the ATLAS [2] experiment encounter lengthy compilation/linking times. To augment this situation, the IRIS Development Platform was built as a software development framework acting as compiler, cross-project linker and data fetcher, which allow hot-swaps in order to compare various versions of software under test. The flexibility fostered by IRIS allowed modular exchange of software libraries among developers, making it a powerful development tool. The IRIS platform used input data ROOT-ntuples [3];however a new data model is sought, in line with the facilities offered by IRIS. The schematic of a possible new data structuring—as a user implemented object oriented data base, is presented.

Integration of PSSE Web Application with Power System Simulation Platform

As power systems become larger and more complicated, power system simulation analysis requires more flexibility and faster performance. BPA is simulation software that is widely used in China and thus official power system data are in BPA format. However, BPA＇s flexibility and performance cannot meet the requirement of ultra-large-scale power system. PSSE supports user-def＇med models and can handle large scale power system with up to 150,000 buses. From that perspective, PSSE is much suitable for future network analysis. To take advantages of both BPA and PSSE, it is required to build a simulation platform which is able to combine PSS^E with BPA to meet the requirements of large-scale power system simulation in the future. In this paper, PSS^E and BPA have been integrated into the power system simulation platform to perform power system study together. As data format and models are different between BPA and PSSE, the focus is developing a converter that can convert BPA data to PSSE data and creating dynamic models in PSSE based on the dynamic models in BPA. Simulation results show the accuracy of PSSE user-defined models and high availability of PSSE Web application.

Vibration analysis of two-dimensional structures using micropolar elements

Based on the micropolar theory(MPT),a two-dimensional(2 D)element is proposed to describe the free vibration response of structures.In the context of the MPT,a 2 D formulation is developed within the ABAQUS finite element software.The user-defined element(UEL)subroutine is used to implement a micropolar element.The micropolar effects on the vibration behavior of 2 D structures with arbitrary shapes are studied.The effect of micro-inertia becomes dominant,and by considering the micropolar effects,the frequencies decrease.Also,there is a considerable discrepancy between the predicted micropolar and classical frequencies at small scales,and this difference decreases when the side length-to-length scale ratio becomes large.

Modeling and Simulation of Laser Assisted Turning of Hard Steels

This research work is focused on simulation of laser assisted turning as a new solution for machining of hard steels. A transient, three-dimensional model was developed to predict the temperature distribution of a rotated cylindrical steel workpiece subjected to a localized heating using a moving Gaussian laser beam. In this regard, a User-Defined Function was created to overcome the problem of a moving Gaussian heat source’ definition. This User-Defined Function was compiled into a finite volume software package (Fluent), where three-dimensional single precision solver was used for analysis. Based on this model, simulation of the surface temperature of 32 mm diameter workpiece of AISI51 50H steel was performed as a function of time at a specific distance behind the laser beam spot, which is corresponding to 30° angle from the laser beam. The simulation results were compared with other published data of the same steel type where a close agreement was obtained. The verified model was used for simulation of laser assisted turning of 20 mm diameter workpiece of AISI D2 tool steel. The cutting depth, behind the laser beam, was set at a distance corresponding to 60° angle from the laser beam for having sufficient access for handling both laser head and cutting tool. This cutting depth was studied as a function of different lasers and machining parameters. The results indicated that the optimum parameters for successful laser-assisted turning process of the concerned steels are 800 W laser power, 5 mm laser beam spot diameter, 20 sec preheating time, 0.8 mm/sec laser scanning speed, 300 rpm rotational speed and 0.8 mm/sec feed rate. These parameters ensure easy/successful cutting of 1 mm depth in one pass without deteriorating the properties of the remaining bulk material. It can be deduced that the developed model might provide a useful tool for online process control of different steel types regardless of their physical properties and geometries.

Numerical simulation of coupling multi-physical field in electrical arc furnace for smelting titanium slag

The smelting reduction process of the ilmenite in an electric arc furnace(EAF)is a commonly used technology for producing titanium slag in the world.It has particular significance to analyze the velocity-temperature-electromagnetics multi-physical field in an EAF for improving its productivity and reducing energy consumption.A transient three-dimensional mathematical model was developed to characterize the flow,heat transfer,and electromagnetic behavior in a titanium slag EAF.For describing the electromagnetic field and its effects on velocity and temperature distribution in the furnace,magnetohydrodynamic equations and conservation equations for mass,momentum,and energy were solved simultaneously by compiling the user-defined function program.The numerical model was verified by comparing with the literature data.The results indicate that the Lorentz force is the main driving force of the velocity and temperature distribution.Moreover,the influence of input current and location of electrodes on the multi-physical field distribution was also investigated.It is found that the appropriate range of input current and diameter of pitch circle are about 30,000 A and 3000-3500 mm,respectively.The mathematical model established can characterize the multi-physical field more accu-rately than before,which can provide valuable guidance for the operation improvement and design optimization of the EAF for producing titanium slag.

A Target Tracking System for Applications in Hydraulic Engineering

A new type of digital video monitoring system (DVMS) named user defined target tracking system (UDTTS), was developed based on the digital image processing (DIP) technology and the practice demands of construction site management in hydraulic engineering. The position, speed, and track of moving targets such as humans and vehicles, which could be calculated by their locations at anytime in images basically, were required for management. The proposed algorithm, dependent on the context-sensitive moving information of image sequences which was much more than one or two images provided, compared the blobs’ properties in current frame to the trajectories of targets in the previous frames and then corresponded them. The processing frame rate is about 10fps with the image 240-by-120 pixels. Experimental results show that position, direction, and speed measurements have an accuracy level compatible with the manual work. The user-define process makes the UDTTS available to the public whenever appropriate.

Stress analysis and damage evolution in individual plies of notched composite laminates subjected to in-plane loads

This work aims to investigate local stress distribution, damage evolution and failure of notched composite laminates under in-plane loads. An analytic method containing uniformed boundary equations using a complex variable approach is developed to present layer-by-layer stresses around the notch. The uniformed boundary equations established in series together with conformal mapping functions are capable of dealing with irregular boundary issues around the notch and at infinity. Stress results are employed to evaluate the damage initiation and propagation of notched composites by progressive damage analysis（PDA）. A user-defined subroutine is developed in the finite element（FE） model based on coupling theories for mixed failure criteria and damage mechanics to efficiently investigate damage evolution as well as failure modes. Carbon/epoxy laminates with a stacking sequence of [45°/0°/ 60°/90°]sare used to investigate surface strains, in-plane load capacity and microstructure of failure zones to provide analytic and FE methods with strong validation. Good agreement is observed between the analytic method, the FE model and experiments in terms of the stress（strain） distributions, damage evaluation and ultimate strength, and the layerby-layer stress components vary according to a combination effect of fiber orientation and loading type, causing diverse failure modes in individuals.

Effects of Structural Characteristics of a Bionic Dragonfly Wing on Its Low Velocity Impact Resistance

The influence of the structural features of dragonfly wings, including the sandwich-type configuration of longitudinal veins and the longitudinal corrugations, on the impact response of a bio-inspired structure is investigated. According to experimental observations of the wing morphology, a novel foam-based composite structure is introduced consisting of E-glass/epoxy face-sheets bonded to a polyurethane foam core. A finite element model is employed to simulate the structural responses of the biomimetic structure under low velocity impact. The initiation and evolution of the impact-induced damage in composite skins are simulated by applying a user-defined progressive damage model together with the interracial cohesive law for intra- and inter-laminar damages, respectively. To simulate the nonlinear behavior of the foam core, a crushable plasticity model is implemented. The numerically obtained results are found to correlate with the experimentally measured ones, acquired by drop-weight testing on a bio-inspired structure. It is numerically predicted that reinforcing the structure with the veins gives the more impact load-bearing capacity and the longitudinal corrugation can increase the stiffness and damage resistance of the structure. Effects of the change in impact location, the configuration of the veins and the corrugated angle on damage resistance of the structures are fully discussed.

Distributed and Weighted Extreme Learning Machine for Imbalanced Big Data Learning

The Extreme Learning Machine（ELM） and its variants are effective in many machine learning applications such as Imbalanced Learning（IL） or Big Data（BD） learning. However, they are unable to solve both imbalanced and large-volume data learning problems. This study addresses the IL problem in BD applications. The Distributed and Weighted ELM（DW-ELM） algorithm is proposed, which is based on the Map Reduce framework. To confirm the feasibility of parallel computation, first, the fact that matrix multiplication operators are decomposable is illustrated.Then, to further improve the computational efficiency, an Improved DW-ELM algorithm（IDW-ELM） is developed using only one Map Reduce job. The successful operations of the proposed DW-ELM and IDW-ELM algorithms are finally validated through experiments.

Designing Motion Gesture Interfaces in Mobile Phones for Blind People

Despite the existence of advanced functions in smartphones, most blind people are still using old-fashioned phones with familiar layouts and dependence on tactile buttons. Smartphones support accessibility features including vibration, speech and sound feedback, and screen readers. However, these features are only intended to provide feedback to user commands or input. It is still a challenge for blind people to discover functions on the screen and to input the commands. Although voice commands are supported in smartphones, these commands are difficult for a system to recognize in noisy environments. At the same time, smartphones are integrated with sophisticated motion sensors, and motion gestures with device tilt have been gaining attention for eyes-free input. We believe that these motion gesture interactions offer more efficient access to smartphone functions for blind people. However, most blind people are not smartphone users and they are aware of neither the affordances available in smartphones nor the potential for interaction through motion gestures. To investigate the most usable gestures for blind people, we conducted a user-defined study with 13 blind participants. Using the gesture set and design heuristics from the user study, we implemented motion gesture based interfaces with speech and vibration feedback for browsing phone books and making a call. We then conducted a second study to investigate the usability of the motion gesture interface and user experiences using the system. The findings indicated that motion gesture interfaces are more efficient than traditional button interfaces. Through the study results, we provided implications for designing smartphone interfaces.