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High-performance p-type silicon target materials of Co-doped B and Al elements were produced using Ga and P contaminated upgraded metallurgical-grade silicon (UMG-Si) at the industrial scale. The purity of silicon ingots is above 5.5 N after the directional solidification process, which meets market demand. The segregation behavior of elements and compensation effect on the resistivity are discussed. The effective segregation coefficients of B, Al, Ga, and P for ingot No. 1 were approximately 0.66, 0.14, 0.38, and 0.49, respectively. The segregation coefficients of P, Ga, and Al become larger, the segregation effect tends to become smaller, which is attributed to the doped and contaminated elements that have the recombination effect on the holes and electrons. The distribution of resistivity can be regulated precisely by the compensation difference [NA–ND] along the solidified fraction. The mean resistivity of the ingots is approximately 0.013 Ω cm. Prolonging melting time is conducive to the uniform distribution of doping elements.

n-type multicrystalline silicon ingot with a doping element of phosphorus was produced by directional solidification under industrial conditions. The evaporation and distribution of phosphorus were studied by content analysis in different positions. The results show that it is mainly controlled by melting and solidification processes. During the melting process, the content of phosphorus reduced from 16.6 and 6.7 ppmw to 11.1 and 6.0 ppmw under different melting times, respectively. The evaporation of phosphorus is mainly affected by the temperature. During the solidification process, the segregation of phosphorus was promoted by evaporation. A formula similar to the Scheil equation was established to calculate the longitudinal distribution of phosphorus in silicon. The results show that its longitudinal distribution is influenced by the evaporation coefficient, the solidification rate, and the temperature gradient. The effective segregation coefficient of phosphorus in ingots a and b was 0.31 and 0.33, respectively, which could be obtained from the fitting result. During the whole process, the phosphorus removal efficiency in ingots a and b was 60.8% and 50.5%, respectively. Its horizontal distribution is related to the morphology of the solid–liquid interface.

High-performance multicrystalline silicon (HPMC-Si) wafers were produced using upgraded metallurgical-grade silicon (UMG-Si) materials in the seed-assisted growth system at the industrial scale. The HPMC-Si wafers yielded low dislocation density and fine and uniform grain size. We observed that fine grain size suppressed the segregation effect of metal impurities. The effective segregation coefficients of Fe, Al, and total metal impurities approximated 0.265, 0.492, and 0.386, respectively. The concentration of impurities within 10–90% of the solidified fraction in the ingot was relatively uniform based on the improved crystal structure control. The heterogeneous nucleation mechanism of concave and planocera nucleation was discussed intensively. HPMC-Si wafers were obtained under the crystal structure control coupled with behavior regulation of impurity segregation in the seed-assisted growth system. The average conversion efficiency of Al-BSF processed solar cells reached 18.65%.

The diffusion layer thickness of impurity during directional solidification process was evaluated under different temperature gradient conditions. The thickness of Fe, Cu, Ni and Ti in silicon ingot under 9.74 K/m were 6.19 mm, 4.92 mm, 4.61 mm and 8.70 mm, respectively; The thickness of Fe, Cu, Ni and Ti in silicon ingot under 28.49 K/m were reduced to 3.35 mm, 1.21 mm, 1.85 mm and 5.81, respectively. The diffusion layer thickness was reduced by the large temperature gradient to lead a low effective segregation coefficient. As a result, the impurity concentration of silicon ingot under 28.49 K/m was reduced to 0.94 ppmw. The strong vortex in the solid-liquid boundary interface was enhanced by the large temperature gradient, as the main transport mechanism to accelerate the diffuse of impurity atom in the diffusion layer，which effectively reduced the thickness of diffusion layer.

A multicrystalline silicon ingot with columnar and irregular grains was obtained from metallurgical-grade silicon (MG-Si) by directional solidification. The segregation behaviors of substitutional and interstitial impurities in different grain morphologies have been studied. The concentration distribution of substitutional impurities (B and Al) in the silicon ingot was accord with the Scheil's equation, which depended on the grain morphology. However, the concentration distribution of interstitial impurities (Fe, Ti, Cu, and Ni) was only accord with the Scheil's equation under the columnar grains growth condition. The difference lattice sites of the impurities will result in the disparate segregation behavior of impurities for columnar and irregular grains growth, which leads to the diverse concentration distribution of substitutional and interstitial impurities in the silicon ingot. Furthermore, the transport mechanism of interstitial and substitutional impurities in front of the solid-liquid interface boundary has been revealed.

A silicon target material with the purity of 99.999 wt% (99.999%) was prepared by adding Al–B master alloy in directional solidification. The segregation behavior of the dopant and the effect on the resistivity were studied in this work. It was revealed that the AlB2 particles in the Al–B master alloy will generate the clusters of [B] and [Al] in molten silicon at 1723 K spontaneously. The concentrations of B and Al were increasing gradually along the solidified fraction in the silicon ingot. The measured values of B were in good agreement with the curve of the Scheil’s equation below 85% of the solidified fraction. The measured values of Al were fitting well with the curve of the Scheil’s equation when the effective segregation coefficient is 0.00378. It was found that the resistivity of the silicon target material was regulated by B co-doped Al simultaneously in directional solidification.

Silicon ingots with columnar grains and irregular grains as raw material for solar cells were obtained by directional solidification. The relationship between crystal morphology and concentration of metal impurities was studied. The result shows that columnar grains can improve the ratio of the high-purity area, where the concentration of metal impurities is less than 10 ppmw and more consistent with the calculated value by the Scheil’s equation. Meanwhile, the metal silicide precipitates at the irregular grain boundaries. Large temperature gradient at the solid-liquid interface dedicated to the stability of solid-liquid interface, which is conductive to the growth of the columnar grains. High concentration of metal impurities introduces a large constitutional supercooling to reduce the stability of solid-liquid interface, then further form a mushy zone in front of the solid-liquid interface, which leads to the growth of irregular grains.

The distribution of insoluble inclusions in multi-crystalline ( m -c) silicon was investigated by directional solidification under different vacuum conditions using recycled scraps. We found an abnormal peak (weight ratio of 1.19%) of SiC and Si 3 N 4 with an average size of 100 μm located at the bottom of the silicon ingot obtained under low-vacuum conditions. At the top of the ingot, the impurity phase featured a weight ratio exceeding 10.62% and a size of 20 μm. Results showed that large particles sank to the bottom of the ingots whereas small particles floated upward. Further investigation suggested that the dominant factor influencing inclusion distribution is related to the presence of metallic impurities (e.g., Ca, Al, and Na) and their corresponding microstructure. A mechanism of migration was proposed to reveal that bonding of metallic impurities and insoluble inclusions contribute to the abnormal distribution of impurities. The results provide guidance for controlling the distribution of insoluble inclusions in recycled m -c silicon.

Multicrystalline silicon ingots without and with alternating magnetic field during directional solidification process under industrial system were obtained from metallurgical grade silicon (MG-Si). The concentrations and normalized concentrations of metal impurities in the two silicon ingots were studied. The result shows that the concentrations and normalized concentrations in high-purity area of the silicon with alternating magnetic field are lower than those of the ingot without alternating magnetic field. The transport mechanism for metal atoms in the diffusion layer area has been changed due to the alternating magnetic field. Alternating magnetic field introduces a convection to reduce the thickness of diffusion layer in the molten silicon, which results in a decreased effective segregation coefficients. Enhancing transport driving force of metal atoms in molten silicon is the effective way to improve the removal rate of metal impurities.

In this paper, we present a novel approach for transferring shape and expression of a face in image to that of another, regardless of variance between the two faces in illumination, color, texture, resolution and even some mild occlusion. We first use a face alignment algorithm to locate accurate facial landmark points for both original face and target face, then align them with a global similarity transformation to eliminate their inconsistency in pose, size and position. Finally, we use our non-rigid image deformation method to deform the original face by fitting a map function for each of its pixel point according to the two sets of facial landmark points. Our method can be full-automatic or semi-automatic for conveniently tuning a better result by combining a face alignment algorithm and a non-rigid image deformation method. Experiment results show that our method can produce realistic, natural and artifact-less facial shape and expression transfer. We also discuss the limitation and potential of our proposed method.

A hollow silicon ingot was obtained by a solid–liquid separation method inducted by the fountain effect and the formation mechanism of the ingot was also discussed. A layer of solidified shell was formed on the melt surface and the gas dissolved in the melt was separated out. Because of this, the thickness of the shell was gradually increased and expanded due to the sudden change of the chamber pressure leading to the silicon melt being squeezed out from the preset hole of the shell. During this process, the melt left behind contains a high concentration of impurities and can be separated or detached completely from the decontaminated solid. This novel approach has of great potential to inhibit the back diffusion of impurities and to produce a silicon ingot at a high yield rate.

In this paper, we propose a novel closed-form transformation estimation method based on moving regularized least squares optimization with thin-plate spline (MRLS-TPS) for non-rigid image deformation. The method takes the user-controlled point-offset-vectors as the input data, and estimates the spatial transformation about the two control point sets for each pixel. To achieve a realistic deformation, we formulates the transformation estimation as a vector-field interpolation problem by a moving regularized least squares method. Unlike MLS, the mapping function is modeled by a non-rigid function thin-plate spline with regularization technique, such that the deformation can satisfy both global linear affine motion and local non-rigid warping. We derive a closed-form solution of the transformation and achieve a fast implementation. In addition, the proposed method can give a wonderful user experience, fast and convenient manipulating. Extensive experiments on real images demonstrated the proposed method outperforms other state-of-the-art methods and the commercial software Adobe PhotoShop CS 6, especially in case of flexible object motion.

In this paper, a novel closed-form transformation estimation method based on feature guided moving least squares together with manifold regularization is proposed for nonrigid image/surface deformation. The method takes the user-controlled point-offset-vectors and the feature points of the image/surface as input, and estimates the spatial transformation between the two control point sets for each pixel/voxel. To achieve a detail-preserving and realistic deformation, the transformation estimation is formulated as a vector-field interpolation problem using a feature guided moving least squares method, where a manifold regularization is imposed as a prior on the transformation to capture the underlying intrinsic geometry of the input image/surface. The non-rigid transformation is specified in a reproducing kernel Hilbert space. We derive a closed-form solution of the transformation and adopt a sparse approximation to achieve a fast implementation, which largely reduces the computation complexity without performance sacrifice. In addition, the proposed method can give a wonderful user experience, fast and convenient manipulating. Extensive experiments on both 2D and 3D data demonstrate that the proposed method can produce more natural deformations compared with other state-of-the-art methods.

A multicrystalline silicon ingot was obtained from metallurgical-grade silicon by vacuum induction melting and directional solidification. Based on the concentration distributions of aluminum and calcium along the growth direction, the removal mechanism of such impurities with both high saturated vapor pressures and low segregation coefficients is investigated. The results show that the removal of this type of impurities only depends on evaporation during vacuum induction melting process, thus their contents decrease significantly due to the strongly evaporation under the high temperature and high vacuum conditions. During subsequent directional solidification process, a model including both segregation and evaporation is used to simulate the concentration distribution. The results show that the impurity distribution is controlled by both two mechanisms in the initial stage of solidification and is mainly determined by segregation in the end stage due to the decrease of the diffusibility and evaporability of the impurity atoms.

Silicon is widely used as a raw material for production of solar cells. As a major impurity in silicon, phosphorus must be removed to 1 × 10−5 wt.%. In the present study, based on the distribution of phosphorus in a silicon ingot obtained by vacuum refining and directional solidification, the mechanism for removal of phosphorus from silicon is investigated. The results show that the distribution is controlled not only by segregation at the solid–liquid interface but also by evaporation at the gas–liquid interface, showing some deviation from Scheil’s equation. A modified model which considers both segregation and evaporation is used to simulate the distribution, matching quite well with the experimental results. The temperature and solidification rate are two important parameters that affect the overall mass transfer coefficient and the effective segregation coefficient and thus the distribution of phosphorus. A high removal efficiency and a homogeneous distribution can be obtained by adjusting these two parameters.

Solidification rate has a significant influence on purification of silicon due to segregation of impurities at a liquid–solid interface of a solidifying silicon ingot. A mathematical model is developed to evaluate time-dependent position of the liquid–solid interface and solidification rate of electron beam melted ingots. A series of solidification experiments with different cooling rates are conducted to measure position of a line which separates directionally grown columnar crystals visible in cross-sections of the solidified ingots. Results show that not the whole ingot solidifies directionally when the reduction rate of the beam current is larger than 1.67 mA/s. The position of the dividing line depends on cooling rate and the experimental trend is consistent with that resulted from theoretical simulations. Modeling shows that the solidification rate changes fast when the beam current reduces linearly that is detrimental for segregation of impurities. It also predicts that an exponential reduction of the beam current leads to a uniform solidification rate which is beneficial to segregation of impurities, though not all exponential current reductions lead to this kind of solidification behavior.

Animation generating, which refers to generating a movie or animation according to one or more images, has a number of useful application ranging from movie effects to virtual reality. This paper proposes a novel animation generating method via MRLS image deformation and designs an animation system, which can generate a vividly animation from a static image by choosing set of point handles and deformation paths. Firstly, users need to choose a set of fixed control points and a distorted image deformation path. Then, construct deformation mapping functions according to the control points and the deformation path, and get a series of deformed images with the mapping function. Finally, users get the animation by packaging the deformed images into an AVI video files frame-by-frame. Experiment results show that the non-rigid deformation animations produced with our method are deformed smoothly, naturally and realistically.