Electrical and optical properties of InP nanowire ensemble p⁺-i-n⁺ photodetectors

We report on a comprehensive study of electrical and optical properties of efficient near-infrared p?-i-n? photodetectors based on large ensembles of self-assembled, vertically aligned i-n? InP nanowires monolithically grown on a common p? InP substrate without any buffer layer. The nanowires have a polytype modulated crystal structure of wurtzite and zinc blende. The electrical data display excellent rectifying behavior with an ideality factor of about 2.5 at 300 K. The ideality factor scales with 1/T, which possibly reflects deviations from classical transport models due to the mixed crystal phase of the nanowires. The observed dark leakage current is of the order of merely ～100 fA/nanowire at 1 V reverse bias. The detectors display a linear increase of the photocurrent with reverse bias up to about 10 pA/nanowire at 5 V. From spectrally resolved measurements, we conclude that the photocurrent is primarily generated by funneling photogenerated carriers from the substrate into the NWs. Contributions from direct excitation of the NWs become increasingly important at low temperatures. The photocurrent decreases with temperature with an activation energy of about 50 meV, which we discuss in terms of a temperature-dependent diffusion length in the substrate and perturbed transport through the mixed-phase nanowires.     

Free spectral range measurement of fabry-perot cavity using frequency modulation

In this paper, we propose a novel method to measure the free spectral range (FSR) of a Fabry-Perot cavity (FPC) using single-frequency modulation (FM) with one electric optical modulator (EOM) and the null method. A laser beam modulated by the EOM, to which a cosine-wave signal is supplied from a radio frequency (RF) oscillator, is incident on the FPC. The transmission light from the FPC is observed and converted to an RF signal by a highspeed photodetector, and the RF signal is synchronously demodulated with a lock-in amplifier (LIA) by referring to the oscillator. We theoretically and experimentally demonstrate that the LIA signal become null with a steep slope, when the modulation frequency equals the FSR under the condition that the carrier frequency is slightly detuned from the resonance of the FPC. The experimental results show that the proposed method has the capability to determine the FSR by the null method with a small measurement uncertainty.     

Studies on sustainable features of vernacular architecture in different regions across the world: A comprehensive synthesis and evaluation

Due to the increasing pressure brought by recent global environmental problems, building designers are embracing regionalism and the knowledge of traditional structures, arguing that these structures are energy efficient and highly sustainable. We observe clear evidence of the increasing interest in vernacular architecture among the research community. This study therefore aims to clarify the contents and issues raised in the studies on vernacular architecture and the knowledge and recommendations that can be derived from them. A database of the research is established by collecting many studies from primary sources. Obtained data is carefully refined and categorized into a table where synthesized information is introduced. The results of this study show an uneven geographic and climatic distribution of the studies; the trend in selecting research objectives and research objects; the choice of research methods with a clear shift towards quantitative research methods, and the generic findings from the database of the research. These results can support diverse inquiries about vernacular architecture across the world and be used as a resource or an orientation to support numerous subsequent studies.     

Surface-enhanced-Raman-scattering-inducing nanoprobe for spectrochemical analysis

This paper describes a new nanoprobe that induces the surface-enhanced Raman scattering (SERS) effect when brought into contact with chemicals on any type of surface. The SERS-inducing probe was fabricated from an optical fiber that was tapered to a tip 100 nm in diameter. A thin layer of silver islands was applied to the tip of the tapered fiber via thermal evaporation to induce the SERS effect. The small scale of the tip may be amenable to localized, nondestructive SERS-based analyses of surfaces with high spatial selectivity. Because the contact probe itself induces the SERS effect, no modification of the sample is required. Direct analysis at submicrometer spatial selectivity is therefore possible for analyte compounds on any type of surface. Various optimization studies and preliminary evaluations were performed. A 10-nm silver thickness was determined to yield the optimum SERS effect. A 25% relative standard deviation in SERS signal was observed for five different probe tips. As a demonstration of the SERS-inducing capability of the probe, Raman spectra were recorded for glass surfaces coated with brilliant cresyl blue and p-aminobenzoic acid before and during contact with the SERS-inducing nanoprobe.     

基于圆环形薄壁截面梁的温度自补偿拉力传感器

提出一种基于圆环形薄壁截面梁的温度自补偿的拉力传感方法。将2个反射波长相同的光纤布拉格光栅(FBG)刚性粘贴于圆环形薄壁截面梁的外表面,其间距为相距90°。当拉力的作用线与其中一个光栅在同一直径上时,2个光栅反射峰的间距与拉力的大小呈线性关系,而对温度变化不敏感,从而实现了温度自补偿的拉力传感。实验中,温度自补偿传感的拉力达到7 kgN。     

Structural and Electrical Characterization of Carbon Nanofibers for Interconnect Via Applications

We present temperature-dependent electrical characteristics of vertically aligned carbon nanofiber (CNF) arrays for on-chip interconnect applications. The study consists of three parts. First, the electron transport mechanisms in these structures are investigated using I-V measurements over a broad temperature range (4.4 K to 350 K). The measured resistivity in CNF arrays is modeled based on known graphite two-dimensional hopping electron conduction mechanism. The model is used because of the disordered graphite structure observed during high-resolution scanning transmission electron microscopy (STEM) of the CNF and CNF-metal interface. Second, electrical reliability measurements are performed at different temperatures to demonstrate the robust nature of CNFs for interconnect applications. Finally, some guidance in catalyst material selection is presented to improve the nanostructure of CNFs, making the morphology similar to multiwall nanotubes.     

BBS网络监听与检测系统研究

文章给出了一种BBS监听与检测的实现方案.该系统由底层捕包,重组过滤和二次分析检索三部分分布实现.底层捕包采用winpcap以过滤大部分的无用数据.重组过滤只将论坛文本信息还原并在剔除干扰字符的基础上采用平衡二叉树进行关键字匹配进一步过滤合法文本,提高了系统性能较少丢包率.二次分析检索对捕获的非法信息进行帐密检测并根据其帐密触发安全响应.