梁柱节点不同强度等级混凝土的施工

结合工程施工配合,提出当柱子混凝土强度等级大于梁混凝土强度等级（尤其高层建筑）时的施工方法和施工中应当注意的问题.     

10.6μm激光对石英晶体的辐照效应

用连续波10.6μm CO2激光辐照石英晶体基片表面,利用X射线衍射分析仪、紫外-可见分光光度计、荧光光度计等对辐照前后晶体相变、透射-吸收特性和表面缺陷进行了测试、分析。研究表明,经10.6μm激光辐照后石英晶体样品表面的相结构发生了一定的转变,其吸收率降低而透射率增加,而且晶体表面缺陷得到一定的修复。石英晶体在CO2激光辐照下,经历了一个快速升温和降温的过程,较高温度及热应力作用是导致石英晶体表面微观结构及光学性能变化的主要原因。     

AES Algorithm of Improving WPAN Throughput

The throughput of WPAN (Wireless Personal Area Network) based on Bluetooth was decided by the interference of Bluetooth piconets in the network. The interference was decided by the hamming correlation of Bluetooth FH (Frequency Hopping) selected sequence. In order to improve the WPAN throughput, the WPAN model and data packet collision model were built and the relations about WPAN throughput, the maximum hamming correlation of FH selected sequence, the numbers of Bluetooth piconets and the SNR of channel were analyzed. The functions of WPAN throughput were deduced. After analyzing the performance of Bluetooth FH selected sequence, the original algorithm was replaced by the AES (Advanced Encryption Standard) algorithm. The theoretical analysis proved that the AES FH sequences selected algorithm could improve the WPAN throughput. The simulation results proved the theoretical analysis. The test result with ARM926EJs SoC (System on Chip) + RF (Radio Frequency) chip nRF2401 and CSR??s Bluecore4 Bluetooth module got the same conclusion. All of these could prove that the AES algorithm can improve the WPAN throughput efficiently.     

Affine invariant image watermarking using intensity probability density-based Harris Laplace detector

Feature point based image watermarking against geometric distortions has attracted great attention in recent years. However, for the state-of-the-art intensity based feature points detectors, the feature points often gather at textured portions of the image or on the edges where the change of intensity is significant, so that many feature points capture the same portion of the image, which makes the watermark be vulnerable to local geometric distortions. In this paper, we propose an affine invariant image watermarking scheme with good visual quality and reasonable resistance toward local geometric distortions, which utilizes the intensity probability density-based Harris–Laplace detector. Firstly, the uniform and robust feature points are extracted by utilizing modified Harris–Laplace detector, in which the intensity probability density gradient is used instead of intensity gradient. Then, the affine invariant local ellipse regions (LERs) are constructed adaptively according to the variation of local intensity probability density. Finally, the digital watermark is embedded into the affine invariant LERs in nonsubsampled contourlet transform (NSCT) domain by modulating the lowpass NSCT coefficients. By binding the watermark with the affine invariant LERs, the watermark detection can be done without synchronization error. Experimental results show that the proposed image watermarking is not only invisible and robust against common image processing operations such as sharpening, noise adding, and JPEG compression, but also robust against the global affine transforms and local geometric distortions.     

Model-based adaptive resolution upconversion of degraded images

Resolution upconversion of a degraded image is an ill-posed inverse problem that is even harder than video superresolution due to lack of redundant observations from reference frames. To overcome this difficulty an adaptive 2D piecewise autoregressive (PAR) model is used to strengthen the constraints on the solution of the inverse problem. The PAR model can be fit to local image waveforms by adjusting its parameters. But estimating the model parameters needs the knowledge of the very original high-resolution pixels to be estimated by the model. We resolve this chicken-and-egg dilemma by adaptive nonlinear least-squares joint estimation of both model parameters and original pixels. This non-linear estimation problem is solved by the method of structured total least-squares, constrained by the degradation function (e.g., the point spread function of a camera plus noises) that forms the observed low-resolution image. As such, this work offers a unified general framework for joint upsampling, deconvolution, and denoising. Moreover, the upsampling can be carried out at an arbitrary scale rather than power of two. Experiments show that the proposed NEARU technique outperforms current methods in both PSNR and subjective visual quality, and its advantage becomes greater for larger scaling factors.     

A 9,9′-bianthracene-cored molecule enjoying twisted intramolecular charge transfer to enhance radiative-excitons generation for highly efficient deep-blue OLEDs

The efficiency of fluorescent organic light emitting diodes (FOLEDs) is strongly affected by the fraction of singlet excitons formed. However, the standard statistical value of the single to triplet ratio is 1:3, which implies most of the excitons are invalid in fluorescent emitting devices. Here, we demonstrate the ability of twisted intramolecular charge transfer state (TICT-state) to enhance the occurrence of singlet excitons in a fluorescent emitter that is based on the 9,9′-bianthracene (BA) moiety. The anthracene–anthracene (A–A) linked by a single bond and having perpendicular electronic structure is a charge transfer intersystem crossing π system in excited state. The BA-cored fluorescence emitter (CzBACz) with particular TICT characteristics realizes the electron–hole (e–h) recombination via intramolecular conversion from charge-transfer excitons (immediate precursor) to radiative singlet exciton (final state). For CzBACz-based electroluminescent (EL) device, the singlet generation fraction is more than 25%.     

Efficient Terahertz Photoconductive Emitters with Improved Electrode Structures

We present the design,fabrication,and characterization of two new types of terahertz photoconductive emitters.One has an asymmetric four-contact electrode structure and the other has an arc-shaped electrode structure,which are all modified from a traditional strip line antenna.Numerical simulations and real experiments confirm the good performance of the proposed antennas.An amplitude increase of about 40%is experimentally observed for the terahertz signals generated from the new structures.The special electrode structure and its induced local bias field enhancement are responsible for this radiation efficiency improvement.Our work demonstrates the feasibility of developing highly efficient terahertz photoconductive emitters by optimizing the electrode structure.     

Scattering Properties of Cylindrical Ferrite Posts and Their Applications

The scattering field of a ferrite post and a cylindrical ferrite post containing conducting post illuminated by a plane wave is analyzed. The special interest is the scattering property of the ferrite posts, which is resonating at certain modes such as TM₁₁ mode. We hope to know the speciality it shows and find its applications. It is found that the scattering field pattern of a resonating ferrite post is similar to the rotation of the scattering field pattern of a dielectric cylindrical post, which has the same dimension as ferrite. The scattering properties of the ferrite may give us some inspirations to explore its applications in microwave components. This property is utilized to explain the mechanism of the operation of the circulators. It also may be used in microstrip patch antenna, coupler and filter to control their properties. Other applications may be possible too. Some calculation results are presented.