Computed tomographic evaluation of gas hole formation and structural quality in Gouda‐type cheese

Computed tomography (CT) was performed on Gouda‐type cheese during ripening to evaluate gas hole formation and structural quality. The cheese was exposed to different ripening conditions, including variations in ripening temperature and concentration of butyric acid bacteria. Computed tomography images were obtained every 2 weeks for 16 weeks to assess the volume, shape and location of gas holes. The results demonstrate that CT makes the nondestructive monitoring of cheese gas hole formation and evaluation of the structural features of cheese possible throughout the ripening period.     

Green fluorescence of terbium ions in lithium fluoroborate glasses for fibre lasers and display devices

In this paper, for the first time, the visible fluorescence properties, resonance energy transfer mechanism responsible for non-radiative decay rates of ⁵D₄ → ⁷F₅ transition and also quenching of fluorescence intensity of the ⁵D₃ → ⁷F₅ transition of various concentrations of Tb³⁺ ions in LBZLFB glasses are reported. Optical absorption, fluorescence spectra and quantum efficiencies are measured and analysed. Green fluorescence related to ⁵D₄ → ⁷F₅ (548 nm) transition is registered under excitation of 378 nm of Tb³⁺ ions. Based on excitation and fluorescence measurements, several spectroscopic parameters for Tb³⁺ ions are examined as a function of concentration by Judd–Ofelt theory to judge the suitability of studied glasses for display devices and fibre lasers.     

Effective parameters on diameter of carbon nanotubes by plasma enhanced chemical vapor deposition

The effective parameters on the diameter of carbon nanotubes (CNTs) by plasma enhanced chemical vapor deposition (PECVD) were presented.Among lots of influential parameters,the effects of the catalytic film thickness and the pretreatment plasma power on the growth of CNTs were investigated.The results show that the size of catalytic islands increases by increasing the thickness of catalytic layer,but the density of CNTs decreases.The pretreatment duration time of 30 s is the optimal condition for growing CNTs with about 50 nm in diameter.By increasing the pretreatment plasma power,the diameter of CNTs decreases gradually.However,the diameter of CNTs does not change drastically from 80 to 120 W.The uniformly grown CNTs with the diameter of 50 nm are obtained at the pretreatment plasma power of 100 W.     

File and workload allocation on a local multi-access computer network: incorporating local processing and communication overhead

The paper presents an analytical model to allocate files and workload simultaneously among heterogeneous servers for a distributed database where the servers are connected by a local multi-access computer network. The allocation problem is presented in the form of a nonlinear integer programming model. The model incorporates both local processing and communication overhead. The problem is proved to be NP-complete and thus a heuristic is developed. To illustrate its suitability, the heuristic is compared with an exhaustive enumeration method for small problems and with a genetic algorithm for large problems. Computational results demonstrate that the proposed model and heuristic provide effective database designs     

Development of oxide dispersion strengthened ferritic steels with and without aluminum

Pure Fe,Cr,Al,Ti elemental powders and prealloyed Y2O3 powder were processed by high energy mechanical milling.The compositions of the mixed powders are designed as Fe-18Cr-0.2Ti-0.35Y2O3 and Fe-18Cr-5...     

平流层通信新思路——谷歌气球计划

平流层通信具有低延迟、信道衰落小、造价低廉、机动灵活等特点,在军事应用和应急通信领域都有重要的战略价值,也曾经引起各国的重视,并成为研究热点。然而平流层通信平台的稳定性对各国研究者而言一直是一个挑战,谷歌公司从鸟群飞行中得到启发,开启了Google Loon项目,其目的是为全球偏远地区2/3人口提供速度较快、价格可承受的互联网接入服务,同时为自然灾害发生地区提供通信服务。文中分析了谷歌气球的技术细节,谷歌气球初次试验的情况,以及谷歌气球面临的挑战。谷歌气球计划为平流层通信提供了又一新思路。     

Comparison of three‐dimensional analysis and stereological techniques for quantifying lithium‐ion battery electrode microstructures

Lithium‐ion battery performance is intrinsically linked to electrode microstructure. Quantitative measurement of key structural parameters of lithium‐ion battery electrode microstructures will enable optimization as well as motivate systematic numerical studies for the improvement of battery performance. With the rapid development of 3‐D imaging techniques, quantitative assessment of 3‐D microstructures from 2‐D image sections by stereological methods appears outmoded; however, in spite of the proliferation of tomographic imaging techniques, it remains significantly easier to obtain two‐dimensional (2‐D) data sets. In this study, stereological prediction and three‐dimensional (3‐D) analysis techniques for quantitative assessment of key geometric parameters for characterizing battery electrode microstructures are examined and compared. Lithium‐ion battery electrodes were imaged using synchrotron‐based X‐ray tomographic microscopy. For each electrode sample investigated, stereological analysis was performed on reconstructed 2‐D image sections generated from tomographic imaging, whereas direct 3‐D analysis was performed on reconstructed image volumes. The analysis showed that geometric parameter estimation using 2‐D image sections is bound to be associated with ambiguity and that volume‐based 3‐D characterization of nonconvex, irregular and interconnected particles can be used to more accurately quantify spatially‐dependent parameters, such as tortuosity and pore‐phase connectivity.