Structural and operational management of Turkish airports: a bootstrap data envelopment analysis of efficiency

This paper explores the structural and operational dimensions of the efficiencies of airports. The two-stage procedure is suggested to assess the efficiencies of airports in this study. In the first-stage, Classification and Regression Tree, which is one of the machine-learning approaches used to divide the airports into homogeneous and thus comparable sub-groups. In the second stage, the bootstrap data envelopment analysis approach obtains more precise structural and operational efficiency scores. To illustrate the proposed framework use, we applied it to a real case associated with Turkish airports. The results demonstrate that this framework presents a more comprehensive assessment of airport performance rather than conventional data envelopment analysis models. Moreover, it provides to show the deficiencies of the structural and operational management of airports. The findings can help anywhere airport authorities as well as Turkish airport authorities.     

Performance improvement of microbial fuel cell through artificial intelligence

The current work introduces an enhancement in the performance of the microbial fuel cell through estimating the optimal set of controlling parameters. The maximization of both power density (PD) and the percentage of chemical oxygen demand (COD) removal were considered as the enhancement in the cell's performance. Three main parameters in terms of performance as well as commercialization are the system's inputs; the Pt which takes the range of 0.1‐0.5 mg/cm², the degree of sulphonation in sulfonated‐poly‐ether‐ether‐ketone that changes in the range of 20‐80%, and the rate of aeration of cathode which varies between 10 and 150 mL/min. From the experimental dataset, two robust adaptive neuro‐fuzzy inference system models based on the fuzzy logic technique have been constructed. The comparisons between the models' outputs and the experimental data showed well‐fitting in both training and testing datasets. The mean squared errors of the PD model, for testing and whole datasets, were found 2.575 and 0.909 while for the COD model it showed 19.242 and 6.791, respectively. Then, based on the two fuzzy models, a Particle Swarm Optimization algorithm has been used to determine the best parameters that maximize both of the PD and the COD removal of the cell. The optimization process was utilized for single and multi‐object optimization processes. In the single optimization, the resulting maximums of the PD and the COD removal were found 62.844 (mW/m²) and 99.99 (%), respectively. Whereas, in the multi‐object optimization, the values of 61.787 (mW/m²) and 96.21 (%) were reached as the maximums for the PD and COD, respectively. This implies that, in both cases of optimization processes, the adopted methodology can efficiently enhance the microbial fuel cell performances than the previous work.     

Biomechanical response of the human foot when standing in a natural position while exposed to vertical vibration from 10–200 Hz

Exposure to foot-transmitted vibration (FTV) can lead to pain and numbness in the toes and feet, increased cold sensitivity, blanching in the toes, and joint pain. Prolonged exposure can result in a clinical diagnosis of vibration-induced white foot (VIWFt). Data on the biomechanical response of the feet to FTV is limited; therefore, this study seeks to identify resonant frequencies for different anatomical locations on the human foot, while standing in a natural position. A laser Doppler vibrometer was used to measure vertical (z-axis) vibration on 21 participants at 24 anatomical locations on the right foot during exposure to a sine sweep from 10–200?Hz with a peak vertical velocity of 30?mm/s. The most notable differences in the average peak frequency occur between the toes (range: 99–147?Hz), midfoot (range: 51–84?Hz) and ankle (range: 16–39?Hz).

Practitioner Summary: The biomechanical response of the human foot exposed to foot-transmitted vibration, when standing in a natural position, was measured for 21 participants. The foot does not respond uniformly; the toes, midfoot, and ankle regions need to be considered independently in future development of isolation strategies and protective measures.     

枪管结构对固有频率的影响

为了研究枪管结构对枪管固有频率的影响,针对枪管尤其是狙击枪管设计中约束长度、枪管外形、膛口装置以及膛线等不同结构,建立了相应的三维模型。采用以六面体为主的网格对枪管进行了网格划分,采用有限元方法对枪管进行了模态分析。计算获得了不同结构枪管的固有频率; 通过比较,得到了不同枪管结构对固有频率的影响。分析结果表明:枪管尾部螺纹长度越长,枪口振动幅度越低; 相同质量枪管,锥形外形枪管刚度最好; 加装膛口装置对枪管刚度和振动特性有不利影响。     

Bioprospecting for brewers: Exploiting natural diversity for naturally diverse beers

The burgeoning interest in archaic, traditional, and novel beer styles has coincided with a growing appreciation of the role of yeasts in determining beer character as well as a better understanding of the ecology and biogeography of yeasts. Multiple studies in recent years have highlighted the potential of wild Saccharomyces and non-Saccharomyces yeasts for production of beers with novel flavour profiles and other desirable properties. Yeasts isolated from spontaneously fermented beers as well as from other food systems (wine, bread, and kombucha) have shown promise for brewing application, and there is evidence that such cross-system transfers have occurred naturally in the past. We review here the available literature pertaining to the use of nonconventional yeasts in brewing, with a focus on the origins of these yeasts, including methods of isolation. Practical aspects of utilizing nondomesticated yeasts are discussed, and modern methods to facilitate discovery of yeasts with brewing potential are highlighted.     

乙二醇高温还原制备燃料电池核壳结构Cu@Pt-Pd电极的研究

通过对以碳为核心的燃料电池电催化剂Cu@Pt-Pd的制备方法的研究,以还原法成功将Cu、Pt、Pd还原到了靶核C上制备出了核壳结构电催化剂Cu@Pt-Pd。该催化剂以Cu为核来提升催化剂的表面积比,同时掺杂金属Pd,降低贵金属铂的使用量,在提高催化效率的同时可以降低成本。经过对所制备的催化剂的XRD和CV的测试与分析,探究出制备的成品具有一定的提升氧化还原反应的催化效率的能力,同时该制备方法简单易于操作,利于大量制备。     

Drilling machinability of engineering ceramics under low-frequency axial vibration processing by sintering/brazing composite diamond trepanning bit

Thin-wall diamond trepanning bits are extensively used for processing hard and brittle materials such as engineering ceramics. However, it is difficult to achieve high-efficiency processing of engineering ceramics at a constant feed speed, because of high dynamic compressive strength, high hardness, and low density of engineering ceramics. In this study, a novel composite diamond bit combining sintering and brazing has been designed, along with the low-frequency axial vibration technology, to realize the continuous hole processing of engineering ceramics. Drilling experiments have been conducted on Al₂O₃ and SiC engineering ceramics with a constant feed speed. The variation of axial force, micromorphology of hole wall surface drilled, as well as the method of removing nesting during the drilling process were analyzed. According to the results, the novel composite diamond bit fabricated by combining sintering and brazing, can achieve the continuous hole processing of engineering ceramics at a constant feed speed, including Al₂O₃ and SiC. Compared to the conventional drilling (CD), the low-frequency axial vibration drilling (LFVD) can significantly reduce the axial force, and produce fewer plastic scratches on the hole wall surface drilled. In particular, the automatic blanking ratio approaches to 100% by LFVD, and only about 73.58% by CD. It can be concluded that LFVD technology can be used to realize continuous hole processing of engineering ceramics. The research results achieved in this study show that the drilling machinability of engineering ceramics by LFVD and novel composite diamond bit is good. Accordingly, this study provides a useful reference for continuous processing or batch production of engineering ceramics at a constant feed speed.     

APP软件性能效率研究

性能效率是APP软件的重要质量属性，但目前缺乏APP软件性能效率的通用模型。分析了APP软件的性能特征，基于ISO/IEC 25010标准提出了APP软件的性能效率模型，定义了APP软件性能效率的子特性和度量指标。基于提出的APP软件性能效率模型，通过实验对APP软件的性能效率进行了度量及相关分析。     

Collection efficiency of liquid‐based samplers for fungi in indoor air

This study assessed the collection efficiency (CE) of two popularly used sampling devices (BioSampler and Coriolis sampler) for fungal aerosols. Phosphate‐buffered saline (PBS) supplemented with or without surfactant (Tween‐20, Tween‐80, or Triton X‐100) and antifoam agent was prepared and used as collection liquids. The agar impactor (BioStage) was simultaneously operated with liquid‐based samplers to collect fungi from seven sites located at a university building, public library, and animal farming. Fungal concentrations determined by liquid samplers were divided by those by BioStage, and the ratio values represented CE. Results indicate that the CE of BioSampler was superior to that of Coriolis (P = 0.0001) and the PBS containing surfactant collected fungi better than that without surfactant (P < 0.0001), whereas antifoam agent showed no influence (P = 0.8). Moreover, fungal concentrations determined by BioSampler with surfactant‐added PBS were statistically indifferent from those by BioStage (P > 0.05) with a Spearman correlation coefficient of 0.81‐0.83 (P < 0.01). In addition to sampler and collection liquid, sampling location was also identified as a significant CE factor (P = 0.006), implying potential influences by fungal genera in the studied fields. Overall, BioSampler with surfactant‐supplemented PBS (eg, Triton X‐100) is recommended considering the great CE and compatibility with a variety of analytical assays.     

液压缸非线性弹簧力约束下轧机吸振器参数的优化

考虑四辊轧机液压缸非线性弹簧力约束的因素,引入吸振器控制装置,建立带有轧机吸振器的轧机辊系振动动力学模型;通过对轧机吸振器基本参数的优化,得出吸振器最优的阻尼系数和刚度系数;仿真分析不同质量、弹簧力、摩擦力对轧机辊系振动幅频特性曲线的影响规律,得到轧机吸振器的最优质量可以有效提高系统稳定性,轧机吸振器的最优弹簧力可以缩小系统的不稳定区域,轧机吸振器的最优摩擦力可以有效降低幅频特性曲线的高度,为有效抑制轧机辊系垂直振动提供理论支持。