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991.
用化学计量学方法分析小兴安岭7种松科植物松叶挥发油气相色谱-质谱(GC-MS)数据,为松叶挥发油的药理活性与其它的应用研究提供依据。(1)用直观推导式演进特征投影(heuristic evolving latent projections,HELP)法分辨重叠色谱峰,得各组分的纯色谱峰和质谱;(2)用正交投影法比较不同挥发油的GC-MS数据;(3)用峰面积归一化法确定各化合物的相对含量;(4)用主要化学成分进行聚类分析。7种松叶挥发油的化学成分为单萜、倍半萜及其衍生物和酯类化合物,按化学成分7种松叶挥发油可分为3类。 相似文献
992.
Yun Sheng Alexei Sourin Gabriela Gonzalez Castro Hassan Ugail 《The Visual computer》2010,26(6-8):975-984
Three-dimensional (3D) representations of complex geometric shapes, especially when they are reconstructed from magnetic resonance imaging (MRI) and computed tomography (CT) data, often result in large polygon meshes which require substantial storage for their handling, and normally have only one fixed level of detail (LOD). This can often be an obstacle for efficient data exchange and interactive work with such objects. We propose to replace such large polygon meshes with a relatively small set of coefficients of the patchwise partial differential equation (PDE) function representation. With this model, the approximations of the original shapes can be rendered with any desired resolution at interactive rates. Our approach can directly work with any common 3D reconstruction pipeline, which we demonstrate by applying it to a large reconstructed medical data set with irregular geometry. 相似文献
993.
在分析通用双极性输出D/A转换器的基础上,给出了Π型电阻网络单元及串联电阻计算方法,提出了一种全新的Π型双极性输出D/A转换器,该电阻网络电阻个数少、阻值选取方便,有重要的理论及应用价值。 相似文献
994.
995.
996.
针对电力线通信自适应OFDM系统的限制条件,探讨在每OFDM符号内各RT用户要求的约束下,研究系统总功率地窖注水分配后多子载波上的速率自适应子载波分配模型,提出一种新的动态子载波组分配算法。在典型电力线信道环境下对其仿真,并与另外两种分配算法进行比较,结果表明,本文动态子载波组分配算法的复杂度大大减小,能满足多用户资源分配的多目标要求。 相似文献
997.
998.
Sheng Li Jie Hu Ying-Hong Peng 《Engineering Applications of Artificial Intelligence》2010,23(4):569-585
The conceptual design process of a complex product concerns multidisciplinary design knowledge. This paper presents an approach of consistent knowledge representation for conceptual design. Firstly, the concept of functional micro-knowledge cell (FMKC) is presented, and the knowledge representation approach of FMKC is proposed. In the function layer, the functional ontology is used to provide a rich vocabulary. By constructing the mapping relationships between the function and structure layer, a systematic knowledge representation scheme is obtained. Secondly, the functional knowledge decomposition theory is proposed to unify the resolution of knowledge representation. Finally, the FMKC is applied to a hydraulic cylinder, which demonstrates the possibility in representing the multidisciplinary knowledge for conceptual design with a unified systematic representation scheme. In addition, the FMKC can be used in knowledge fusion and design reuse for our further study. 相似文献
999.
A novel dual-mass resonant output micromechanical gyroscope is proposed which utilizes resonant sensing as the basis for Coriolis force detection instead of displacement sensing. It can overcome the shortcoming of single-mass resonant output micromechanical gyroscope and can reduce the common mode acceleration error by using a dual-mass topology structure and lever differential mechanism. The structure and operating principle of the device are introduced. Moreover, some important theoretical analyses of the gyroscope are provided in detail. The analytical results have shown that the resonant frequencies of vibrating mass and double-ended tuning fork resonators are 3.153 and 62.853 kHz. The device has a frequency sensitivity of 12.535 Hz/deg/s and a mechanical noise floor of $ 7.957\deg /{\text{h}}/\sqrt {{\text{Hz}}} A novel dual-mass resonant output micromechanical gyroscope is proposed which utilizes resonant sensing as the basis for Coriolis
force detection instead of displacement sensing. It can overcome the shortcoming of single-mass resonant output micromechanical
gyroscope and can reduce the common mode acceleration error by using a dual-mass topology structure and lever differential
mechanism. The structure and operating principle of the device are introduced. Moreover, some important theoretical analyses
of the gyroscope are provided in detail. The analytical results have shown that the resonant frequencies of vibrating mass
and double-ended tuning fork resonators are 3.153 and 62.853 kHz. The device has a frequency sensitivity of 12.535 Hz/deg/s
and a mechanical noise floor of
7.957deg/\texth/?{\textHz} 7.957\deg /{\text{h}}/\sqrt {{\text{Hz}}} in air. The finite element simulation results verify the accuracy of analytical algorithms. The common mode acceleration
error of device can be reduced by 97.6%. The device is fabricated by SOG (Silicon on Glass) micro fabrication technology.
Some important performances are measured by experimental method. The micromechanical gyroscope can be used to estimate the
rotation rate by further implementing the signal processing electronics. 相似文献
1000.
Tao Sheng Xinglei Zhu Guogang Hua Hongxing Guo Jingli Zhou Chang Wen Chen 《Multimedia Systems》2010,16(2):127-137
In most existing Wyner–Ziv video coding schemes, a feedback channel (FC) is expected at the decoder in order to allocate a
proper bit rate for each Wyner–Ziv frame. However, FC not only results in additional latency but also increases decoding complexity
due to the several feedback-decoding iterations. Moreover, FC may be unavailable in many practical video applications. In
this paper, we propose a novel feedback-free rate-allocation scheme for transform domain Wyner–Ziv video coding (TD-WZVC),
which predicts the rate for each Wyner–Ziv frame at the encoder without significantly increasing the complexity of the encoder.
First, a correlation estimation model is presented to characterize the relationship between the source frame and the reference
frame estimated at the encoder in TD-WZVC. Then, an efficient FC-free rate-allocation algorithm is proposed and a linear model
is built to avoid both overestimation and underestimation of the real rate and obtain an optimal rate-distortion performance.
Experimental results show that the proposed scheme is able to achieve a good encoder rate allocation while still maintaining
consistent coding efficiency. 相似文献