步进频率探地雷达的实时处理器软件设计

数据预处理是探地雷达系统中的一项重要内容,针对步进频率探地雷达的数据处理工作量大的特点,引入数字信号处理器(DSP)来完成数据预处理任务.在此基础上,构建了DSP处理软件的整体框架,详细设计了软件的各功能模块,并定义了数据的通信协议.所设计软件具有良好的拓展性和可选择性,经实际数据测试,在处理时间上能够满足实时性的要求.     

Small Changes,Big Impact: Tungsten Bronzes with Extremely Large Second Harmonic Generation Achieved by the Transition Metal Doping on the B-Site

Two novel transition metal-doped tungsten bronze oxides, Pb_2.15Li_0.85Nb_4.85Ti_0.15O₁₅ (PLNT) and Pb_2.15Li_0.55Nb_4.85W_0.15O₁₅ (PLNW), are synthesized by high-temperature solid-state reactions. The Rietveld method using the high-resolution synchrotron radiation indicates that PLNT and PLNW crystallize in the orthorhombic polar noncentrosymmetric space group, Pmn2₁ (no. 31). As a class of tungsten bronze oxide, PLNT and PLNW retain a unique rigid framework composed of d⁰ transition metal cation (Ti⁴⁺ or W⁶⁺)-doped highly distorted NbO₆ octahedra along with the subsequently generated Pb/LiO₁₂ and PbO₁₅ polyhedra. Interestingly, the d⁰ transition metal-doped tungsten bronzes, PLNT and PLNW, exhibit extremely large second-harmonic generation (SHG) responses of 56 and 67 × KH₂PO₄, respectively. The observed immeasurably strong SHG is mainly attributed to a net polarization originating from the alignment of highly distorted NbO₆ octahedra with doped transition metals in the frameworks. It is believed that doping transition metal cations at the B-site of the tungsten bronze structures should be an innovative strategy to develop novel high-performance nonlinear optical materials.     

Designing Metallic and Insulating Nanocrystal Heterostructures to Fabricate Highly Sensitive and Solution Processed Strain Gauges for Wearable Sensors

All‐solution processed, high‐performance wearable strain sensors are demonstrated using heterostructure nanocrystal (NC) solids. By incorporating insulating artificial atoms of CdSe quantum dot NCs into metallic artificial atoms of Au NC thin film matrix, metal–insulator heterostructures are designed. This hybrid structure results in a shift close to the percolation threshold, modifying the charge transport mechanism and enhancing sensitivity in accordance with the site percolation theory. The number of electrical pathways is also manipulated by creating nanocracks to further increase its sensitivity, inspired from the bond percolation theory. The combination of the two strategies achieves gauge factor up to 5045, the highest sensitivity recorded among NC‐based strain gauges. These strain sensors show high reliability, durability, frequency stability, and negligible hysteresis. The fundamental charge transport behavior of these NC solids is investigated and the combined site and bond percolation theory is developed to illuminate the origin of their enhanced sensitivity. Finally, all NC‐based and solution‐processed strain gauge sensor arrays are fabricated, which effectively measure the motion of each finger joint, the pulse of heart rate, and the movement of vocal cords of human. This work provides a pathway for designing low‐cost and high‐performance electronic skin or wearable devices.     

热处理非晶态Ni-P合金镀层的晶化过程

运用电沉积的方法在45钢基体上制备Ni-P合金镀层,使用差示扫描量热法(DSC)和热重法(TG)分析非晶态NiP合金镀层在20℃/min加热速率下的热效应和质量变化。在300℃和400℃分别对镀层进行0,15,30,45,60,75min的热处理,采用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、显微硬度计对镀层进行表征。结果表明:Ni-P合金镀层在加热过程中的放热峰出现在284.8℃处,镀层的质量和元素组成稳定;晶化过程经历了非晶态、亚稳态NiP和Ni5P2、稳定态Ni3P的转变;经过热处理后,镀层的显微硬度显著提高,最大值达1036.56HV,约为镀态的2倍;热处理态镀层的耐NaCl溶液腐蚀性能比镀态有所下降,但两者都比45钢基体好。     

Electrochemical corrosion behavior of 2A02 Al alloy under an accelerated simulation marine atmospheric environment

The corrosion behavior of 2A02 Al alloy under simulated marine atmospheric environment has been studied using mass-gain, scanning electron microscope/energy dispersive spectroscopy (SEM/EDS), laser scanning confocal microscopy, X-ray diffraction spectroscopy and localized electrochemical methods. The results demonstrate that the relationship between the corrosion induced mass-gain and the corrosion time is in accordance with the power rule. The mass-gain increases gradually during the corrosion time, while the corrosion rate decreases. With ongoing of the corrosion, corrosion products film changed from a porous to a compact structure. The various spectroscopic data show that the corrosion products films composed mainly of Al(OH)₃, Al₂O₃ and AlCl₃. The electrochemical corrosion behavior of the 2A02 Al alloy was studied by electrochemical impedance spectroscopy (EIS).     

Peptidyl Virus-Like Nanovesicles as Reconfigurable “Trojan Horse” for Targeted siRNA Delivery and Synergistic Inhibition of Cancer Cells

The self-assembly of peptidyl virus-like nanovesicles (pVLNs) composed of highly ordered peptide bilayer membranes that encapsulate the small interfering RNA (siRNA) is reported. The targeting and enzyme-responsive sequences on the bilayer's surface allow the pVLNs to enter cancer cells with high efficiency and control the release of genetic drugs in response to the subcellular environment. By transforming its structure in response to the highly expressed enzyme matrix metalloproteinase 7 (MMP-7) in cancer cells, it helps the siRNA escape from the lysosomes, resulting in a final silencing efficiency of 92%. Moreover, the pVLNs can serve as reconfigurable “Trojan horse” by transforming into membranes triggered by the MMP-7 and disrupting the cytoplasmic structure, thereby achieving synergistic anticancer effects and 96% cancer cell mortality with little damage to normal cells. The pVLNs benefit from their biocompatibility, targeting, and enzyme responsiveness, making them a promising platform for gene therapy and anticancer therapy.     

Will the experience of playing a violent role in a video game influence people’s judgments of violent crimes?

The present study investigates the impact of the experience of role playing a violent character in a video game on attitudes towards violent crimes and criminals. People who played the violent game were found to be more acceptable of crimes and criminals compared to people who did not play the violent game. More importantly, interaction effects were found such that people were more acceptable of crimes and criminals outside the game if the criminals were matched with the role they played in the game and the criminal actions were similar to the activities they perpetrated during the game. The results indicate that people’s virtual experience through role-playing games can influence their attitudes and judgments of similar real-life crimes, especially if the crimes are similar to what they conducted while playing games. Theoretical and practical implications are discussed.     

Array SSL VPN如何保障番禺有线办公网的安全运行

企业办公自动化系统的应用十分广泛,随着互联网的高速发展,WEB应用成为主流,OA系统在互联网上的延伸成为大趋势,本文阐述在WEB应用中如何保障数据和系统安全的手段和方法。     

A two-level strategy for segmenting center of interest from pictures

Segmenting center of interests (COIs) from pictures is an important but highly challenging problem for researchers in computer vision and image processing. The capability of understanding the meanings of pictures by computers can lead to breakthroughs in a wide range of applications including Web image search and online picture-sharing communities. In this paper, a two-level strategy is presented, which consists of a rough segmentation stage and a fine segmentation stage. In the first level, a picture is partitioned into four regions by using a block clustering method based on color and texture features, and the COI within the picture is distinguished from the background according to the principles of photographic composition. This stage aims to determine the approximate region of the target. In the second level, a novel active contour model is established based on shape information and vector method, where the image energy is defined by a hue gradient and the external energy is generated from either a triangular inner force or a supplementary force. This stage tries to extract the boundary of the target accurately. Experimental results on photos downloaded from the Internet show the feasibility and effectiveness of the proposed method.