结合软硬数据的连续型多点地质统计渗透率图像模拟方法

渗透率图像的预测模拟对油田的开发具有重要意义。充分利用条件数据可以提高渗透率模拟的精度,因此提出一种基于连续型多点地质统计法和软硬数据的渗透率图像模拟方法。首先,利用过滤器得分操作对渗透率图像降维,所有的过滤器得分形成了一个过滤器得分空间;其次,通过两步划分法将得分空间划分,得到每个非空得分类的特征,形成一个“特征库”;最后,通过自定义的距离函数从“特征库”提取已知模式的特征,以完成对节点的模拟。比较各情况下渗透率模拟图像可以看出,将软硬数据同时作为条件数据的模拟图像由于采用了较为丰富的条件数据信息,因此与真实情况下的渗透率分布在结构特征上最为接近。     

Four-scanning attack on hierarchical digital watermarking method for image tamper detection and recovery

In a recent paper presented by Lin et al., a block-based hierarchical watermarking algorithm for digital images is proposed. It adopts parity check and the intensity-relation check to conduct the experiment of image tamper detection. Their experimental results indicate that the precision of tamper detection and localization is 99.6% and 100% after level-2 and level-3 inspections, respectively. The proposed attacks demonstrate that this watermarking algorithm is fundamentally flawed in that the attacker can tamper a watermarked image easily without being detected. In this paper, a four-scanning attack aimed to Lin et al.'s watermarking method is presented to create tampered images. Furthermore, in case they use encryption to protect their 3-tuple-watermark, we proposed a blind attack to tamper watermarked images without being detected. Experimental results are given to support and enhance our conclusions, and demonstrate that our attacks are successful in tampering watermarked images.     

Replication of nanostructures on microstructures by intermediate film mold inserted hot embossing process

The present study proposes a simple method to replicate nano/micro combined multiscale structures using an intermediate film mold and anodic aluminum oxide (AAO) nanomold in hot embossing process. The proposed method is simply to add an intermediate film mold with microscale thru-hole patterns to the ordinary mold system, on which nanostructures are patterned, in the hot embossing process. The intermediate film mold is inserted between polymer substrate and AAO nanomold. During the hot embossing process, the polymer first fills microscale thru-hole patterns in the intermediate film mold and subsequently fills nanopores in AAO nanomold, resulting in the nano/micro combined structures. The intermediate film molds, which have microscale thru-hole patterns were fabricated by micro-milling, laser ablation, etching methods and/or LIGA process. The nano/micro combined structures were successfully replicated by the proposed method.     

Collapse-free thermal bonding technique for large area microchambers in plastic lab-on-a-chip applications

Bonding is an essential step to form microchannels or microchambers in lab-on-a-chip applications. In this paper, we present a novel plastic thermal bonding technique to seal and form large area microchambers (planar characteristic width and length on the order of 1 mm and characteristic thickness on the order of 10–100 μm) without collapse by introducing a holed pressure equalizing plate (HPEP) that includes holes of the same size and shape as the microchambers. To demonstrate the proposed technique, two types of large area microchambers [(1) 20 × 10 mm and 40 μm thick and (2) 12 × 2.5 mm and 120 μm thick] with microchannels were designed and replicated on plastic substrates by means of hot embossing and injection molding processes with prepared two nickel mold inserts. The replicated large area microchambers as well as the microchannels in the plastic lab-on-a-chip were successfully sealed (i.e., no leakage) and formed without any collapse by the proposed thermal bonding technique with the help of the HPEP.     

A neural network-based approach for dynamic quality prediction in a plastic injection molding process

This paper presents an innovative neural network-based quality prediction system for a plastic injection molding process. A self-organizing map plus a back-propagation neural network (SOM-BPNN) model is proposed for creating a dynamic quality predictor. Three SOM-based dynamic extraction parameters with six manufacturing process parameters and one level of product quality were dedicated to training and testing the proposed system. In addition, Taguchi’s parameter design method was also applied to enhance the neural network performance. For comparison, an additional back-propagation neural network (BPNN) model was constructed for which six process parameters were used for training and testing. The training and testing data for the two models respectively consisted of 120 and 40 samples. Experimental results showed that such a SOM-BPNN-based model can accurately predict the product quality (weight) and can likely be used for various practical applications.     

基于SOPC的通用图像处理系统设计

本文介绍了基于SOPC的通用嵌入式图像处理系统的实现方法.其中叙述了SOPC及Nios Ⅱ嵌入式处理器的特点和使用,分别具体说明了系统的硬件结构设计和图像处理算法的流程及软件实现,采用此系统可以大大简化图像处理系统的硬件和软件设计,优化系统设计.     

UHF RFID读写器零中频解调方式的研究与实现

在对UHF RFID读写器工作原理进行分析的基础上,介绍一种工作在UHF频段下的读写器的射频接口电路,并确定读写器的解调方式,重点对正交零中频解调方式进行研究,并给出读写器的实现方案.     

协同办公自动化系统的设计与研究

本文从介绍办公自动化的概念入手,通过对OA应用现实困境的分析,就协同办公自动化系统的需求分析、设计思想和总体设计(包括信息集成平台和OA应用平台)、技术平台进行阐述、分析和比较,并对未来OA的发展趋势作以预测。     

Two-dimensional optical wavelet transform in space domain and its performance analysis

A new architecture of an optical wavelet transform system with a lenslet array is proposed, and its optical performance and optical limits are analyzed.     

Paving the Way for High-Performance UVB-LEDs Through Substrate-Dominated Strain-Modulation

AlGaN-based ultraviolet-B light-emitting diodes (UVB-LEDs) exhibit great potential in phototherapy, vitamin D3 synthesis promotion, plant growth regulation, and so on. However, subjected to the excess compressive strain induced by the large lattice mismatch between multiple quantum wells (MQWs) and AlN, UVB-LEDs that simultaneously satisfy the requirements of high light output power (LOP), low working voltage, and excellent stability are rarely reported. Here, a substrate-dominated strain-modulation strategy is proposed. By precisely manipulating the strain in AlN grown on nano-patterned sapphire substrate (NPSS) to a slightly tensile one, the compressive strain in the following Al_0.55Ga_0.45N underlayer and Al_0.28Ga_0.72N/Al_0.45Ga_0.55N MQWs is successfully suppressed. As a result, an outstanding UVB-LED with a peak wavelength at 303.6 nm is achieved. The 20 × 20 mil² UVB-LED chip shows a wall-plug efficiency (WPE) of 3.27% under a forward current of 20 mA and a high LOP of 57.2 mW with an extremely low voltage of 5.87 V under a forward current of 800 mA. It is more exciting that the LOP degradation is as low as 17% after 1000 h operation under a forward current density of 75 A cm⁻², showing excellent stability. The here-developed UVB-LED, with a high LOP and excellent reliability, will definitely promote the applications of AlGaN-based UVB-LEDs.