In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The...In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The hollow-roll model has equivalent stiffness of bending resistance and deformation to the real solid and much less meshes,so the computational time is greatly reduced.Based on these,the factors influencing plate profile,such as the roll-bending force,initial crown,thermal crown and heat transfer during rolling and inter-pass cooling can be taken into account in the simulation.The auto mesh-refining module with data passing can automatically refine and re-number elements and transfer the nodal and elemental results to the new meshes.Furthermore,the 3-D modeling routine is parametrically developed and can be run independently of Marc pre-processing program.A seven-pass industrial hot rolling process was continuously simulated to validate the accuracy of model.By comparison of the calculated results with the industrial measured data,the rolling force,temperature and plate profile are in good accordance with the measured ones.展开更多
In this paper, the composition of the hardware-in-the-loop simulation system of missile guidance system and the characteristic and function of every equipment in this simulation system are discussed. Then the principl...In this paper, the composition of the hardware-in-the-loop simulation system of missile guidance system and the characteristic and function of every equipment in this simulation system are discussed. Then the principle of this system is discussed in terms of theory, and the resemblance of prototype system with simulation system is analyzed. Also, many key problems such as equipment interface, equipment installation, modelling and software design are dealt with. At the end, the error source of simulation system is analyzed, and a strong base is built for the study of simulation system precision.展开更多
Wavelet has been used as a powerful tool in the signal processing and function approximation recently. This paper presents the application of wavelets for solving two key problems in 3-D audio simulation. First, we em...Wavelet has been used as a powerful tool in the signal processing and function approximation recently. This paper presents the application of wavelets for solving two key problems in 3-D audio simulation. First, we employ discrete wavelet transform (DWT) combined with vector quantization (VQ) to compress audio data in order to reduce tremendous redundant data storage and transmission times. Secondly, we use wavelets as the activation functions in neural networks called feed-forward wavelet networks to approach auditory localization information cues (head-related transfer functions (HRTFs) are used here). The experimental results demonstrate that the application of wavelets is more efficient and useful in 3-D audio simulation.展开更多
This paper presents a formal verification method based on logic simulation. In our method, using symbolic values even circuits which include data paths can be verified without abstraction of data paths. Our verifier e...This paper presents a formal verification method based on logic simulation. In our method, using symbolic values even circuits which include data paths can be verified without abstraction of data paths. Our verifier extracts a transition relation from the state graph (given as a specification) which is expressed using symbolic values, and verifies based on simulation using those symbolic values if the circuit behaves correctly with respect to each transition of the specification. If the verifier terminates with "correct", then we can guarantee that for any applicable input vector sequences, the circuit and the specification behaves identically. We have implemented the proposed method on a Unix workstation and verified some FIFO and LIFO circuits by using it.展开更多
基金Project(20050248007) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The hollow-roll model has equivalent stiffness of bending resistance and deformation to the real solid and much less meshes,so the computational time is greatly reduced.Based on these,the factors influencing plate profile,such as the roll-bending force,initial crown,thermal crown and heat transfer during rolling and inter-pass cooling can be taken into account in the simulation.The auto mesh-refining module with data passing can automatically refine and re-number elements and transfer the nodal and elemental results to the new meshes.Furthermore,the 3-D modeling routine is parametrically developed and can be run independently of Marc pre-processing program.A seven-pass industrial hot rolling process was continuously simulated to validate the accuracy of model.By comparison of the calculated results with the industrial measured data,the rolling force,temperature and plate profile are in good accordance with the measured ones.
文摘In this paper, the composition of the hardware-in-the-loop simulation system of missile guidance system and the characteristic and function of every equipment in this simulation system are discussed. Then the principle of this system is discussed in terms of theory, and the resemblance of prototype system with simulation system is analyzed. Also, many key problems such as equipment interface, equipment installation, modelling and software design are dealt with. At the end, the error source of simulation system is analyzed, and a strong base is built for the study of simulation system precision.
文摘Wavelet has been used as a powerful tool in the signal processing and function approximation recently. This paper presents the application of wavelets for solving two key problems in 3-D audio simulation. First, we employ discrete wavelet transform (DWT) combined with vector quantization (VQ) to compress audio data in order to reduce tremendous redundant data storage and transmission times. Secondly, we use wavelets as the activation functions in neural networks called feed-forward wavelet networks to approach auditory localization information cues (head-related transfer functions (HRTFs) are used here). The experimental results demonstrate that the application of wavelets is more efficient and useful in 3-D audio simulation.
文摘This paper presents a formal verification method based on logic simulation. In our method, using symbolic values even circuits which include data paths can be verified without abstraction of data paths. Our verifier extracts a transition relation from the state graph (given as a specification) which is expressed using symbolic values, and verifies based on simulation using those symbolic values if the circuit behaves correctly with respect to each transition of the specification. If the verifier terminates with "correct", then we can guarantee that for any applicable input vector sequences, the circuit and the specification behaves identically. We have implemented the proposed method on a Unix workstation and verified some FIFO and LIFO circuits by using it.
文摘多环芳烃(polycyclic aromatic hydrocarbons,PAHs)是地下水中的主要有机污染物之一,地下水中多环芳烃运移数值模拟在开展地下水污染高效修复中起重要作用。在实际地下水污染条件下,由于难以准确刻画含水介质中的胶体类型及其分布,通常忽略污染物-胶体共运移机制,建立的模型存在结构误差,导致模型预测具有显著偏差。本研究以荧蒽和菲为研究对象,针对忽略的PAHs-胶体的共运移机制,使用高斯过程回归(Gaussian process regression,GPR)修正模型结构误差,建立耦合数据驱动和物理机制的多环芳烃运移模型。通过饱和砂柱PAHs运移室内试验,对比分析了未耦合和耦合数据驱动方法的模型预测结果。结果表明,忽略PAHs-胶体的共运移机制的地下水多环芳烃运移模型具有显著的模型结构误差,直接进行参数识别不能弥补忽略的共运移机制,预测结果存在显著偏差。使用GPR模型可以有效补偿PAHs-胶体的共运移机制,修正地下水模型的结构误差。验证期荧蒽、菲预测结果的95%置信区间对观测数据的覆盖率分别提升了56.84%和19.04%,纳什系数分别提升了40.09%和21.73%,均方根误差分别降低了33.10%和55.38%,平均绝对误差分别降低了32.00%和46.34%,地下水多环芳烃运移模型的预测性能显著提高。本研究提出的耦合数据驱动和物理机制方法为场地地下水多环芳烃运移精准模拟提供了可行思路,有助于实现地下水污染的精准高效修复。
