Modelling of cubic Bézier curves by electronic circuits

In this paper, analog techniques have been utilized to translate the mathematical formulation of arbitrary functions into electronic circuits which embody instantaneous DC relationships between sets of voltages having a limited dynamic range of variation. Suitable building blocks and electronic circuits have been designed to implement some of the basic functional operations. These functional operations were used to embody an analog modelling technique for the generation of free-form curves based on Bézier curve generation method. To draw a specified curve, the control parameters represented by a group of variable resistors are set at specified positions. These positions correspond to values of the control polygon vertices coordinates that uniquely define the curve shape. To change curve shape, the only requirement is to vary the control parameters represented by the variable resistors, and therefore, the user can use this electronic generation method as a shape designer. Using this analog modelling technique, one can generate curves at speed much more comparable to the alternative software modelling on a digital computer.     

A new method for the fast determination of the data retention lifetime of UV EPROM’s

The newly developped method involves a controlled partial erasure of a charged ultraviolet erasable programmable read only memory device followed by a period of high temperature storage. The model is based on two assumptions: the amount of charge stored at the floating gate of a programmed cell is assumed to be equal throughout a component and the trip the minimum level of charge stored at the floating gate of a programmed cell, has a Gaussian distribution throughout a component. The experimental data are well described by the model. After implementation of the experimental results in the model we extrapolate the data retention lifetimes of the UVEPROM’S under operational conditions. Our measurements show that most of the tested UVEPROM devices (64 ko to 256 ko) have a similar operational lifetime, only the charge leakage activation energy differs (0.35 to 0.9 eV) depending on the type of component. In conclusion this method and model are suitable for a fast determination of UVEPROM’S data retention lifetimes under operational conditions.     

A new fast motion estimation algorithm based on the loop–epipolar constraint for multiview video coding

There lie geometric constraints between neighboring frames in multiview video sequences. The geometric constraints are valuable for reducing spatial and temporal redundancy in multiview video coding (MVC). In this paper, we propose a new fast motion estimation algorithm based on the loop–epipolar constraint which combines loop and epipolar constraints. A practical search technique is designed according to the characteristics of the loop–epipolar constraint. Experimental results show that the proposed algorithm is efficient for sequences under different multiview camera setups.     

A new model-based technique for enhanced small-vessel measurements in X-ray ciné-angiograms

Arterial diameter estimation from X-ray ciné angiograms is important for quantifying coronary artery disease (CAD) and for evaluating therapy. However, diameter measurement in vessel cross sections < or =1.0 mm is associated with large measurement errors. We present a novel diameter estimator which reduces both magnitude and variability of measurement error. We use a parametric nonlinear imaging model for X-ray ciné angiography and estimate unknown model parameters directly from the image data. Our technique allows us to exploit additional diameter information contained within the intensity profile amplitude, a feature which is overlooked by existing methods. This method uses a two-step procedure: the first step estimates the imaging model parameters directly from the angiographic frame and the second step uses these measurements to estimate the diameter of vessels in the same image. In Monte-Carlo simulation over a range of imaging conditions, our approach consistently produced lower estimation error and variability than conventional methods. With actual X-ray images, our estimator is also better than existing methods for the diameters examined (0.4-4.0 mm). These improvements are most significant in the range of narrow vessel widths associated with severe coronary artery disease.     

Intermittent-contact capacitance spectroscopy – A new method for determining C(V) curves with sub-micron lateral resolution

This study introduces a novel method to measure C(V) characteristics of local MOS structures based on scanning probe microscopy (SPM) techniques. The new method operates in intermittent-contact (IC) mode and combines both the advantages of contact mode C(V) spectroscopy and intermittent-contact scanning capacitance microscopy. As a consequence, on the one hand dopant concentration and dopant type can be indicated simultaneously, on the other hand tip wear is reduced significantly.     

Ba0.7Sr0.3TiO3 powders with B2O3 additive prepared by the sol–gel method for use as microwave material

Ferroelectric films based on barium strontium titanates have been widely investigated in microwave devices, such as tunable filters and phase shifters. Recent trends include integration of ferroelectric layers into multilayer dielectric modules by a tape casting procedure. The sintering temperature of BST prepared by the conventional oxide mixing method is, however, very high (1350°C), and only platinum or refractory metals can be used for conductors and electrodes in the co-sintering process of tapes. Decrease of the sintering temperature of BST below 1000°C would result in good compatibility of the ferroelectric layers with embedded electrodes made of highly conductive metals, such as silver. The effects of B₂O₃ addition and powder properties on the sintering behavior and the dielectric properties were investigated. The sol–gel method was used to prepare all powders because of its high purity and homogeneity control and its ability to produce fine powders. The BET results showed that all powders had high specific surface areas, but in dilatometric studies, only boron addition produced the desired shrinkage and dense microstructure at low temperatures (<1000°C). This was also verified in sintered microstructures. The XRD showed an appearing of two secondary phases caused by boron addition. This decreased permittivity and thus set a limit on boron addition.     

A new method for calculation of majority carrier compensation in photovoltaics Zhang Rumin(张汝民)1,2*,Liu Dijun(刘迪军)2,3, Su Guobin(苏国斌)3

在对薄膜太阳能电池的研究中,半导体材料通常包含多个杂质/缺陷态的施主和受主掺杂剂。根据局部电中性（LCN）条件,可以确定平衡费米（EF）水平及电子和空穴浓度。但是LCN方程是一个超越方程,不可能得到它的解析解,只能使用图形或数值方法求解。因此,研究者Chin提出了一种可用于多施主和受主半导体的多数载流子补偿估计的简单近似图解法（GM）。通过引入掺杂排位的概念和阶跃函数,近似的浓度和费米能级变得很容易得到。本文分析的图解法,提出了一种新的数值与图形的方法（NGM）,并对NGM与GM计算精度进行了仿真验证。通过数值计算的引入,GM方法的应用进一步得到了扩展。