Phase-pure iron pyrite nanocrystals for low-cost photodetectors

Earth-abundant iron pyrite (FeS₂) shows great potential as a light absorber for solar cells and photodetectors due to their high absorption coefficient (>10⁵ cm^-1). In this paper, high-quality phase-pure and single crystalline pyrite nanocrystals were synthesized via facile, low-cost, and environment friendly hydrothermal method. The molar ratio of sulphur to iron and the reaction time play a crucial role in determining the quality and morphology of FeS₂ nanocrystals. X-ray diffraction and high-resolution transmission electron microscopy confirm that phase-pure and single crystalline pyrite nanocrystals can be synthesized with high sulphur to iron molar ratio and sufficient reaction time. For the first time, a crystalline nanogap pyrite photodetector with promising photocurrent and UV-visible photoresponse has been fabricated. This work further demonstrates a facile route to synthesize high-quality FeS₂ nanomaterials and their potential in optoelectronic applications.     

提高酸性高锰酸盐指数测定准确性的几个因素

国标法中高锰酸盐指数的测定是一个条件性指标,各操作环节都将影响其测定结果的准确性。本文通过调研大量文献资料,对酸性高锰酸盐指数测定的影响因素进行了总结,希望对相关工作人员的监测工作带来帮助。     

Modeling the customer satisfaction function: a two-country comparison

This paper provides a framework that integrates and reinterprets prior research on satisfaction modeling (function) and proposes the existence of non-linear and curvilinear/higher-order relationships to model online banking customers. It provides a framework that examines two closely related but distinct countries—Malaysia, a developing country, and Singapore, a developed country—and identifies whether modeling online banking customers through satisfaction is unique to each context or is generic. Using a systematic and step-by-step hierarchical moderated regression approach, this study tries to understand the relationship among repurchase intention, satisfaction, and trust, moderated by bank size. Malaysia portrays a linear relationship, while Singapore depicts non-linear and curvilinear/high-order relationships. The findings suggest that modeling online banking customers through satisfaction depends on a country’s economic development. By contrast, prior studies on modeling customers through satisfaction were conducted independently and did not employ proper and systematic steps to capture the satisfaction function.     

The control of spontaneous emission from a three-level atom in an anisotropic photonic crystal with two asymmetric bands

We theoretically investigate the spontaneous emission light of an excited three-level atom embedded in an anisotropic photonic crystal with two asymmetric bands. The property of spontaneous emission relating to the atomic position in a unit cell of the crystal is described with a position-dependent phase difference. The atomic transition in free space can be manipulated by the other associated transition coupling to photonic crystal. The result shows that the spontaneous emission spectra are effectively shifted and tuned by the atomic position-dependent phase, which results in the asymmetric distribution of the photonic density of states between two bands, and the increasing band can push the emitted light towards the other band. The physical process can be further illuminated through analyzing the emitted field in photonic crystal. The result perhaps offers an interesting route towards tunable photonic devices.     

信息化预拼装在钢结构成品检验中的应用

我国的钢结构随着建筑业的高速发展应用领域也得到不断地扩大,复杂钢构件的成品检验成为了工程技术中的瓶颈。本文结合上海中心大厦项目的第三道环带桁架钢构件的信息化预拼装的操作过程,论述了综合利用三维建模软件对复杂空间杆件放样定位优势,以及全站仪精密测量空间坐标的特点,有效地解决复杂钢构件的检测难题,提高复杂钢构件制作精度,保障现场安装顺利进行。     

Generation sites of internal solitary waves in the southern Taiwan Strait revealed by MODIS true-colour image observations

Based on 12 years (2000–2011) of Moderate Resolution Imaging Spectroradiometer (MODIS) true-colour images, statistical characteristics of internal solitary waves (ISWs) in the southern Taiwan Strait were studied. Two types of ISWs with a distinct scale of wave crest length and geographic distributions were identified: Type-I waves have larger wave crest lengths and span a large area from the southern Taiwan Strait to the northern South China Sea, while Type-II waves have smaller wave crest lengths and appear only at the southeastern corner of the Taiwan Strait. Further analyses based on an empirical model of ISW propagation and on the calculations of the depth-integrated internal tide-generating body force suggested that Type-I waves mainly originate from the Luzon Strait, while Type-II waves are locally generated at the shelf break in the southeastern corner of the Taiwan Strait.     

Response sensitivity analysis of the dynamic milling process based on the numerical integration method

As one of the bases of gradient-based optimization algorithms, sensitivity analysis is usually required to calculate the derivatives of the system response with respect to the machining parameters. The most widely used approaches for sensitivity analysis are based on time-consuming numerical methods, such as finite difference methods. This paper presents a semi-analytical method for calculation of the sensitivity of the stability boundary in milling. After transforming the delay-differential equation with time-periodic coefficients governing the dynamic milling process into the integral form, the Floquet transition matrix is constructed by using the numerical integration method. Then, the analytical expressions of derivatives of the Floquet transition matrix with respect to the machining parameters are obtained. Thereafter, the classical analytical expression of the sensitivity of matrix eigenvalues is employed to calculate the sensitivity of the stability lobe diagram. The two-degree-of-freedom milling example illustrates the accuracy and efficiency of the proposed method. Compared with the existing methods, the unique merit of the proposed method is that it can be used for analytically computing the sensitivity of the stability boundary in milling, without employing any finite difference methods. Therefore, the high accuracy and high efficiency are both achieved. The proposed method can serve as an effective tool for machining parameter optimization and uncertainty analysis in high-speed milling.     

Effect of obstacle density on the travel time of the visually impaired people

Because China has put more emphasis on people with disabilities, their living conditions and protection have received increasing attention. In an emergency, the visually impaired people are limited in their ability to evacuate, especially along egress paths with obstacles. This paper studied the relationship between the travel time of visually impaired people and obstacle density in their path. Eight sighted people and 32 people with visual impairments were chosen to carry out the walking experiment. The results of the experiment showed that the travel time of sighted people was shorter than that of visually impaired people under the same obstacle and non‐obstacle situations. Based on the analysis of variance of travel time, it was clear from the results that the travel time of the visually impaired people rapidly increased when there were obstacles. When the obstacle density was kept to within a certain range, there was no obvious increase in travel time. Once the density exceeded this range, there was another obvious increase. Based on this result, it can be seen that keeping the obstacle density to within a certain range could be helpful for the visually impaired people during an evacuation when the egress paths cannot be made obstacle‐free.