A Review of Active Appearance Models

Active appearance model (AAM) is a powerful generative method for modeling deformable objects. The model decouples the shape and the texture variations of objects, which is followed by an efficient gradient-based model fitting method. Due to the flexible and simple framework, AAM has been widely applied in the fields of computer vision. However, difficulties are met when it is applied to various practical issues, which lead to a lot of prominent improvements to the model. Nevertheless, these difficulties and improvements have not been studied systematically. This motivates us to review the recent advances of AAM. This paper focuses on the improvements in the literature in turns of the problems suffered by AAM in practical applications. Therefore, these algorithms are summarized from three aspects, i.e., efficiency, discrimination, and robustness. Additionally, some applications and implementations of AAM are also enumerated. The main purpose of this paper is to serve as a guide for further research.

Elliptic Object Detection Based on Shape Preserving and Active Contour

本文通过形状约束方程(组)与一般主动轮廓模型结合,将目标形状与主动轮廓模型融合到统一能量泛函模型中,提出了一种形状保持主动轮廓模型即曲线在演化过程中保持为某一类特定形状。模型通过参数化水平集函数的零水平集控制演化曲线形状,不仅达到了分割即目标的目的,而且能够给出特定目标的定量描述。根据形状保持主动轮廓模型,建立了一个用于椭圆状目标检测的统一能量泛函模型,导出了相应的Euler-Lagrange常微分方程并用水平集方法实现了椭圆状目标检测。此模型可以应用于眼底乳头分割,虹膜检测及相机标定。实验结果表明,此模型不仅能够准确的检测出给定图像中的椭圆状目标,而且有很强的抗噪、抗变形及遮挡性能。

Carbon monoxide adsorption on molybdenum phosphides: Fourier transform infrared spectroscopic and density functional theory studies

Molybdenum phosphide (MoP) and supported molybdenum phosphide (MoP/gamma-Al2O3) have been prepared by the temperature-programmed reduction method. The surface sites of the MoP/gamma-Al2O3 catalyst were characterized by carbon monoxide (CO) adsorption with in situ Fourier transform infrared (FT-IR) spectroscopy. A characteristic IR band at 2037 cm(-1) was observed on the MoP/gamma-Al2O3 that was reduced at 973 K. This band is attributed to linearly adsorbed CO on Mo atoms of the MoP surface and is similar to IR bands at 2040-2060 cm(-1), which correspond to CO that has been adsorbed on some noble metals, such as platinum, palladium, and rhodium. Density functional calculations of the structure of molybdenum phosphides, as well as CO chemisorption on the MoP(001) surface, have also been studied on periodic surface models, using the generalized gradient approximation (GGA) for the exchange-correlation functional. The results show that the chemisorption of CO on MoP occurred mainly on top of molybdenum, because the bonding of CO requires a localized mininum potential energy. The adsorption energy obtained is DeltaH(ads) approximate to -2.18 eV, and the vibrational frequency of CO is 2047 cm-1, which is in good agreement with the IR result of CO chernisorption on MoP/gamma-Al2O3.

Study of remote sensing based parameter uncertainty in Production Efficiency Models

The remote sensing based Production Efficiency Models (PEMs), springs from the concept of "Light Use Efficiency" and has been applied more and more in estimating terrestrial Net Primary Productivity (NPP) regionally and globally. However, global NPP estimates vary greatly among different models in different data sources and handling methods. Because direct observation or measurement of NPP is unavailable at global scale, the precision and reliability of the models cannot be guaranteed. Though, there are ways to improve the accuracy of the models from input parameters. In this study, five remote sensing based PEMs have been compared: CASA, GLO-PEM, TURC, SDBM and VPM. We divided input parameters into three categories, and analyzed the uncertainty of (1) vegetation distribution, (2) fraction of photosynthetically active radiation absorbed by the canopy (fPAR) and (3) light use efficiency (e). Ground measurements of Hulunbeier typical grassland and meteorology measurements were introduced for accuracy evaluation. Results show that a real-time, more accurate vegetation distribution could significantly affect the accuracy of the models, since it's applied directly or indirectly in all models and affects other parameters simultaneously. Higher spatial and spectral resolution remote sensing data may reduce uncertainty of fPAR up to 51.3%, which is essential to improve model accuracy.

Analysis of strychnos alkaloids using electrospray ionization Fourier transform ion cyclotron resonance multi-stage tandem mass spectrometry

The fragmentations of four strychnos alkaloids have been investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) in the positive ion mode. Experiments using multi-stage tandem mass spectrometry (ESI-FT-ICR-MSn) allowed us to obtain precise elemental compositions of product ions at high mass resolution. The experimental data demonstrated that the nitrogen bridge and the coordinated oxygen atom on the nitrogen bridge in the alkaloid compounds were the active sites in the MS2 fragmentations. The loss of CH3 or the OCH3 group in those alkaloids, which have an OCH3 substituent, was the dominant fragmentation mode in the MS3 fragmentations. Logical fragmentation schemes for strychnos alkaloids have been proposed and these should be useful for the identification of these compounds.

Self-assembled monolayer growth of octanol on mica: Atomic force microscopy and Fourier-transform infrared spectroscopy studies

The growth kinetics of self-assembled monolayers formed by exposing freshly cleaved mica to octanol solution has been studied by atomic force microscopy (AFM) and Fourier-transform infrared spectroscopy (FTIR). AFM images of samples immersed in octanol for varying exposure times showed that before forming a complete monolayer the octanol molecules aggregated in the form of small islands on the mica surface. With the proceeding of immersion, these islands gradually grew and merged into larger patches. Finally, a close-packed film with uniform appearance and few defects was formed. The thickness of the final film showed 0.8 nm in height, which corresponded to the 40degrees tilt molecular conformation of the octanol monolayer. The growth mechanisms consisted of nucleation, growth, and coalescence of the submonolayer films. The growth process was also confirmed by FTIR. And the surface coverage of the submonolayer islands estimated from AFM images and FTIR spectra as a function of immersion time was quite consistent.

Investigation of thermal unfolding process of cyanic adduct of horseradish peroxidase by Fourier transform infrared and circular dichroism spectrometry

Detailed circular dichroism(CD) and Fourier transform infrared (FTIR) studies have been carried out to monitor thermal unfolding of horseradish peroxidase isoenzyme C(HRP) inhibited by CN(HRP-CN). The results suggest that HRP-CN is quite different from native HRP with different spin states of Fe of heme and different coordinated states. Cyanide becomes the sixth ligand of Fe(I) of heme and the hydrogen-binding network is destroyed partly at the same time, which cause the drastic decrease of thermal stability of HRP. The FTIR and Soret-CD spectra analysis demonstrate that during the heating process there is an intermediate state(I') which has both partly destroyed secondary and tertiary structures of native HRP, then it is the appearance of protein aggregation state(A) after fully unfolding. The unfolding pathway thus can be shown as follows: I -->I'-->U -->A.

大别山岩石圈有效弹性厚度初步研究

As powerful tools to study the lithosphere dynamics, the effective elastic thickness (Te) as well as the envelope of yielding stress of lithosphere have been attracted great attention of geoscientists in the past thirty years. The oceanic lithosphere, contrary to the continental lithosphere, has more fruits for its simple structures and evolution process. In continent, the lithosphere commonly is complex and variable in the rheological, thermal structures, and has a complicated history. Therefore, the application of the effective elastic thickness in continent is still a subject to learn in a long time. Te, with the definition of the thickness of an elastic plate in theory flexured by the equal benging of the real stress in the lithosphere plate (Turcotte, 1982), marks the depth of transition between elastic and fluid behaviors of rocks subjected to stress exceeding 100 MPa over the geological timescales (McNutt, 1990). There are three methods often adapted: admittance or isostatic response function, coherence and forwarding. In principle, the models of Te consist of thermal-rheological, non-linear Maxwell, non-linear work hardening and rheological layered models. There is a tentative knowledge of Te that it is affected by the following factors: crustal thickness, crust-mantle decoupling, plate bending, boundary conditions of plate (end forces and bending moments), stress state, sedimentary layer, faulting effect, variation in the mountain belts' strike, foreland basin, inheritance of tectonic evolution, convection of mantle, seismic depth and lithosphere strength. In this thesis, the author introduces the geological sketch of the Dabie collisional orogenic belt and the Hefei Basin. The Dabie Mts. is famous for the ultra-high pressure metamorphism. The crustal materials subducted down to the depth of at least 100 km and exhumed. So that the front subjects arise such as the deeply subduction of continent, and the post-collisional crust-mantle interaction. In a geological journey at June of 1999, the author found the rarely variolitic basaltic andesite in the Dabie Mts. It occurs in Susong Group, near Zhifenghe Countryside, Susong County, Anhui Province. It is just to the south of the boundary between the high-grade Susong melange and the ultra-high grade South Dabie melange. It has a noticeable knobby or pitted appearance in the surface. The size of the varioles is about 1-4 mm. In hand-specimen and under microscope, there are distinct contacts between the varioles and the matrice. The mineralogy of the varioles is primarily radiate plagioclase, with little pyroxene, hornblende and quartz. The pyroxene, hornblende and quartz are in the interstices between plagioclase. The matrix is consisted of glass, and micro-crystals of chlorite, epidote and zoisite. It is clearly subjected and extensive alteration. The andesite has an uncommon chemical composition. The SiO_2 content is about 56.8%, TiO_2 = 0.9%, MgO = 6.4%, (Fe_2O_3)_(Total) = 6.7% ～ 7.6%, 100 Mg/(Mg+Fe) = 64.1 ～ 66.2. Mg# is significantly high. The andesite has higher abundances of large-lithophile trace elements (e.g. K, Ba, Sr, LREE), e.g. La/Nd = 5.56-6.07, low abundances of high-strength-field elements (HFSE, e.g. Ta, Nb, P, Ti), particularly Ta and Nb strongly depleted. These are consistent with the characteristics of subducted-related magmas (Pearcce, 1982; Sun and McDonaugh, 1989). In the spider diagram of trace elements, from Ce to right hand, the abundances of elements decrease quickly, showing a characteristic of the continental margins (Pearce, 1982). There has a strongly enrichment of light-rare-earth elements, with a significant diffraction of REEs (the mean value of (La/Yb)_N is 32.84). No Eu anomaly, but there are anomaly high (La/Yb)_N = 28.63-36.74, (La/Y)_N = 70.33 - 82.84. The elements Y and Yb depleted greatly, Y < 20 ppm, Y_N = 2.74-2.84, Yb_N = 2.18 - 2.35. From the La-(La/Sm) diagram, the andesite is derived from partial melting. But the epsilone value of Nd is -18.7 ～ -19.2, so that the material source may be the mantle materials affected by the crustal materials. The Nd model age is 1.9 Ga indicating that the basaltic andesite was resulted from the post-collisional crust-mantle interaction between the subducted Yangze carton and the mantle of Sino-Korea carton. To obtain the Te of the lithosphere beneath the Dabie Mts. and the Hefei Basin, the author applies the coherence method in this thesis. The author makes two topography-gravity profiles (profiles 7~(th) and 9~(th)) across the Dabie Mts. and the Hefei Basin, and calculates the auto-coherence, across coherence, power spectrum, across power spectrum of the topography and gravity of the two profiles. From the relationships between the coherence and the wave-number of profiles. From the relationships between the coherence and the wave-number of profiles 7~(th) and 9~(th), it is obtained that the characteristic wavelengths respectively are 157 km and 126 km. Consequently the values of effective elastic thickness are 6.5 km and 4.8 km, respectively. However, the Te values merely are the minimum value of the lithosphere because the coherencemethod in a relative small region will generate a systemic underestimation. Why there is a so low Te value? In order to check the strength of the lithosphere beneath the Dabie Mts., the authore tries to outline the yielding-stress envelope of the lithosphere. It is suggested that the elastic layers in the crust and upper mantle are 18 km and 35 km, respectively. Since there exist a low viscosity layer about 3-5 km thickness, so it is reasonable that the decoupling between the crust and mantle occurred. So the effective thickness of the lithosphere can be estimated from the two elastic layers. Te is about 34 km. This is the maximum strength of the lithosphere. We can make an approximately estimation about the strength of the lithosphere beneath the Dabie Mts.: Te is about 20-30 km. The author believes that the following factors should be responsible for the low Te value: (1) the Dabie Mts. has elevated strongly since K_3-J_1. The north part of the Dabie Mts. elevates faster than the south part today; (2) there occur large active striking faults in this area. And in the east, the huge Tan-Lu striking fault anyway tends to decrease the lithosphere strength; (3) the lithosphere beneath the Dabie Mts. is heter-homogeneous in spatio-temporal; (4) the study area just locates in the adjacent region between the eastern China where the lithosphere thickness is significantly reduced and the normal western China. These factors will decrease the lithosphere strength.