烟雾的快速模拟

在粒子系统方法的基础上,比较了近年来的最新研究成果和实际应用方法,采用旋转纹理片的快速烟雾模拟方法,讨论了纹理片的数据结构、各种参数的设置依据和它们对总体模拟效果的影响,给出了具体的模拟步骤,并且通过不同的设置采构造不同的烟雾模拟场景.最后,给出了实际的计算机模拟效果.     

基于混沌查找表的单向Hash函数构造算法

提出一种基于混沌查找表的单向Hash函数构造算法。该算法通过控制符更新的混沌查找表将明文信息映射为查找表中的数据,置换出相应的信息后按照一定的规则提取长度为128 bit的Hash值。理论分析和仿真结果证明,该算法具有较好的单向性、混乱与扩散性以及抗碰撞性,满足单向Hash函数的各项性能要求。     

de Bruijn序列查寻表标签的定值构造法

de Bruijn序列结构是一个查寻表,其核心是它的表标签。因此构造出查寻表标签对于生成de Bruijn序列十分重要。给出一种定值标签构造法,即对大多数节点设定为定值标签,对少部分节点则根据查寻表标签的必要条件指定或任意选定标签。该方法构造的查寻表标签数随着m,n增长而成指数式增长。在局部看是有效的,但与查寻表标签本身数目的惊人增长比较起来就很渺小了。该方法在目前缺乏更好的方法的情况下还是最有效的。     

de Bruijn序列查寻表标签的k位修正构造法

de Bruijn序列的结构是一个查寻表,其核心是它的表标签。因此构造出查寻表标签对于生成de Bruijn序列十分重要。给出两种k位修正构造法。方法1为k位提升构造法,即对大部分节点将其第k（k=1,2,…,n-1）位提升一个定值c（1≤c≤m）,来作为该节点的标签。方法2为k位收缩构造法,即对大部分节点将其第k（k=1,2,…,n-1）位向定值r（0≤r≤m）收缩,来作为该节点的标签。这些方法构造的查寻表标签数随着m,n增长而成指数式增长。与定值构造法一样,在局部看是有效的,但与查寻表标签本身数目的惊人增长比较起来就很渺小。方法2与定值标签构造法比较其速度提高了关于m,n的指数式倍。     

传感器动特性FFT实时处理方法

本文介绍以MCS—96为主控机进行传感器动态信号采样和实时频谱分析的原理,着重叙述FFT实时处理中所涉及的汇编算法,可用简单迅速的查表技术代替复杂费时的数学运算.采样速率达30μs,被检测传感器的工作频带10kHz,可打印出传感器的时域曲线、频域曲线和动态性能指标.其硬、软件可方便地应用到任何传感器智能化及仪器仪表中.     

生成de Bruijn序列的升级算法

提出一种生成de Bruijn序列的升级算法。该算法根据给定的n级de Bruijn序列查寻表标签,采用合成的方法构造出n+1级de Bruijn序列的查寻表标签,从而产生n+1级de Bruijn序列。实验结果表明,该算法是有效的。     

de Bruijn序列间的映射及升级算法

通过由n级de Bruijn序列找出n+1级de Bruijn序列的look-up表标签,并由相应的look-up表求出n+1级de Bruijn序列,从而建立起n级de Bruijn序列到n+1级de Bruijn序列的映射,发现de Bruijn序列间的一种内在联系,导出一类任意元de Bruijn序列的升级算法。     

de Bruijn序列间的映射及降级算法

通过由一个n级de Bruijn序列找出它的LOOK-UP表标签,并由该LOOK-UP表标签经修正找出n-1级LOOK-UP表标签,再由它计算出n-1级de Bruijn序列,从而建立起n级de Bruijn序列到n-1级de Bruijn序列的映射,发现de Bruijn序列间的一种内在联系,导出一类任意元de Bruijn序列的降级算法。     

一种广播数据系统数据帧同步快速算法

广播数据系统接收机在开机后或者经过长时间信号衰减后必须迅速获得同步。传统的标准算法利用接收到的数据序列与校验矩阵相乘来验证是否同步,速度较慢。提出了一种基于查表法的数据帧同步快速算法,将接收到的二进制数据序列与校验矩阵的乘积(模二)问题转化为3字节求余式问题,通过查余式表判断接收机是否达到同步,较大地提高了速度,并显著降低了所需的存储空间。仿真结果表明了该算法的快速性和有效性。     

A hybrid model for real time simulation of urban traffic

In this paper a hybrid model is presented to predict the behavior of traffic in urban area. Intersections and on/off-ramps are modeled by Colored Timed Petri Nets while road links are modeled by a stochastic discrete time model. It is assumed that vehicle routings at each intersection are stochastic. A Particle Filter algorithm based on the hybrid model is developed to estimate the system state. The validation of the model by using real data is discussed. The limited computational effort required makes the model suitable to be used in simulation-based control schemes for urban traffic.     

A novel hybrid data-driven model for multi-input single-output system simulation

Artificial neural network (ANN)-based data-driven model is an effective and robust tool for multi-input single-output (MISO) system simulation task. However, there are several conundrums which deteriorate the performance of the ANN model. These problems include the hard task of topology design, parameter training, and the balance between simulation accuracy and generalization capability. In order to overcome conundrums mentioned above, a novel hybrid data-driven model named KEK was proposed in this paper. The KEK model was developed by coupling the K-means method for input clustering, ensemble back-propagation (BP) ANN for output estimation, and K-nearest neighbor (KNN) method for output error estimation. A novel calibration method was also proposed for the automatic and global calibration of the KEK model. For the purpose of intercomparison of model performance, the ANN model, KNN model, and proposed KEK model were applied for two applications including the Peak benchmark function simulation and the real-world electricity system daily total load forecasting. The testing results indicated that the KEK model outperformed other two models and showed very good simulation accuracy and generalization capability in the MISO system simulation tasks.

     

频率直接数字合成器的一种存储优化方法研究

直接数字频率合成(DDS)是一种先进的频率合成技术.正弦相位-振幅映射是DDS的核心部件之一.正弦查找表方案需要较多片上存储器资源,成本较高,因而,提出了一种基于相邻采样点振幅增量的改进方案.分析改进方案的资源开销,介绍其实现技术,并以FPGA为开发平台实现了改进方案.从功能、误差、最高工作频率、资源开销等方面对改进方案进行了评估.结果表明:改进方案以较小硬件资源额外开销为代价,节约了大量片上存储器资源,同时保证最高工作频率不变.     

牺牲层腐蚀改进模型与模拟研究

牺牲层腐蚀主要受腐蚀液的扩散过程制约,由扩散方程决定.扩散系数在腐蚀过程中随温度和腐蚀液浓度变化而改变.文中对改进的腐蚀模型给出有限差分算法,由每一时刻溶液在具体位置的浓度值得出扩散系数,再由Topography模型计算前端面的腐蚀情况得到腐蚀前端行进的轮廓线.并编程对一些MEMS结构的释放过程进行仿真,最后给出实验验证.     

导弹烟雾的快速模拟

在粒子系统方法的基础上,提出了基于纹理球的快速导弹烟雾模拟方法.讨论了算法的数据结构、各参数设置及其对模拟效果的影响,其中关键参数主要包括纹理球的数量、大小、位置、偏移量、旋转和纹理贴图等.给出了具体的模拟步骤和实际的模拟效果,模拟的速度、效果等比较理想.     

A quantile-based simulation optimization model for sizing hybrid renewable energy systems

As the public has gradually realized the adverse impacts brought by global warming, hybrid renewable energy system (HRES) has become increasingly popular because it can reduce dependence on fossil fuels, while maintaining the stability of power supply. While the HRES is an attractive option in many aspects, the fundamentally uncertain nature of renewable energy sources makes the determination of the proper sizing of the HRES a very challenging task. Contrasting with the existing models that are largely focused on expectation-based system performance, this paper provides a quantile-based simulation optimization model, followed by the development of an efficient solution methodology, to enable the control of the upside risk and, as a result, to enhance the decision quality regarding the sizing of HRES. One advantage of the proposed model is that they can be based on any existing deterministic model that carries a cost structure regarding the sizing of the HRES. Moreover, the proposed solution methodology, consisting of a Monte Carlo simulation method, quantile estimation techniques, and an efficient stochastic optimizer, allows for not only accurate estimation of the objective function value, but also quick identification of the optimal solution due to a uniquely-defined neighborhood structure. An extensive numerical experiment is conducted to verify the efficacy and efficiency of the proposed solution methodology. Finally, in collaboration with a partner in industry, the proposed model and the solution methodology are integrated into a decision support system to provide visualized results for sizing HRES in practice.     

三维烟雾的实时模拟

提出了一种基于流体力学方程并采取欧拉法实时模拟三维真实感烟雾的算法。通过Navier-Stokes方程建立烟雾流场的物理模型,以保证视觉的真实感。为了保证运算的实时性,烟雾流场划分为三维网格空间,并将烟雾速度场的分布定义于每个立方网格单元的中心点;通过线性插值获取整幅图像中每个像素的烟雾浓度。将烟雾模拟技术用于图像的显示特技中,以产生图像消散成烟雾的视觉效果,得到了比较满意的模拟效果。     

火焰动画快速模拟的新方法

针对火焰动画难以快速建模和绘制的问题,提出了完全利用GPU过程化生成火焰动画的高效算法。先用建模工具在预处理阶段构建一个由平面正方形组成的三维模型,在绘制阶段通过GPU编程对这些方形进行Billboard方式的变换,并用一些简单公式对他们的运动方式、大小和颜色来用过程化方式进行控制,最后通过alpha混合得到最终结果。算法完全在GPU里实现,能满足实时的绘制要求。     

Vortex particle smoke simulation with an octree data structure

We propose an octree‐based presentation of vortex particles to simulate smoke and gaseous phenomena in a physical way. Vortex particle method prevails over grid‐based method in terms of less numerical dissipation and more detail features, but it suffers from heavy computational overhead due to per‐particle Biot–Savart integration over the entire simulation space. To alleviate this problem, we employ an octree background grid to separate the vortex particles into individual groups. Particles in groups are aggregated as a single super vortex particle to reduce computational cost. The proposed method produces comparable visual result as previous methods with much less computational overhead. Copyright © 2014 John Wiley & Sons, Ltd.     

门电路延时查找表的凸平滑算法

门电路延时参数的查找表在电路逻辑综合及静态时序分析中均有重要应用。其精度及数学上的凸特性和平滑程度对电路最终的设计结果有较大的影响。基于绝大多数门电路延时模型的实际特性,提出了一种在给定查找表的基础上进行凸平滑的算法。该算法使用了计算机辅助几何设计中的张量积B样条技术,并通过调整样条系数使平滑后得到的延时模型为凸函数。为了使新延时模型的构造快速且准确,样条系数的求解过程被描述为一个半定规划问题,因此得到的新模型具有全局最小的拟合误差。最后以标准单元库门电路通过SPICE仿真得到的查找表数据为实例,并与其他方法进行对照,验证了该方法的有效性和精度。