The Early Stage Wheel Fatigue Crack Detection Using Eddy Current Pulsed Thermography

The in-service wheel-set quality is one of critical challenges for railway safety, especially for the high-speed train. The defect in wheel tread, initiated by rolling contact fatigue (RCF) damage, is one of the most significant phenomena and has serious influence on rail industry. Eddy current pulsed thermography (ECPT) is studied to compensate the Ultrasonic Testing (UT) method for detection these early stage of fatigue cracks in wheel tread. This paper proposes several induction coils, such as linear coil, Yoke coil and Helmholtz coils, based ECPT method to meet the imaging of multiple cracks and irregular surface in wheel tread through numerical simulation and experimental results. Some features are extracted and studied also to quantify the fatigue crack in term of UT and ECPT. The proposed method greatly enhances the capability for cracks detection and quantitative evaluation compared with previous Non-Destructive Testing (NDT) method in railway

A Robust Approach for the Growth of Epitaxial Spinel Ferrite Films

Heteroepitaxial spinel ferrites NiFe2O4 and CoFe2O4 films have been prepared by pulsed laser deposition (PLD) at various temperatures (175 - 690 {\deg}C) under ozone/oxygen pressure of 10 mTorr. Due to enhanced kinetic energy of ablated species at low pressure and enhanced oxidation power of ozone, epitaxy has been achieved at significantly lower temperatures than previously reported. Films grown at temperature below 550 {\deg}C show a novel growth mode, which we term "vertical step-flow" growth mode. Epitaxial spinel ferrite films with atomically flat surface over large areas and enhanced magnetic moment can be routinely obtained. Interestingly, the growth mode is independent of the nature of substrates (spinel MgAl2O4, perovskite SrTiO3, and rock salt MgO) and film thicknesses. The underlying growth mechanism is discussed.Comment: 13 pages, 6 image

Multi-objective optimization for optimum tolerance synthesis with process and machine selection using a genetic algorithm

This paper presents a new approach to the tolerance synthesis of the component parts of assemblies by simultaneously optimizing three manufacturing parameters: manufacturing cost, including tolerance cost and quality loss cost; machining time; and machine overhead/idle time cost. A methodology has been developed using the Genetic Algorithm (GA) technique to solve this multi-objective optimization problem. The effectiveness of the proposed methodology has been demonstrated by solving a wheel mounting assembly problem consisting of five components, two subassemblies, two critical dimensions, two functional tolerances, and eight operations. Significant cost saving can be achieved by employing this methodology

Pilot test of a fermentation tank for producing coal methane through anaerobic fermentation

The development and utilization of clean energy has long been a focus of research. In the coal bed methane field, most coal bed biogenic methane experiments are small static sample tests in which the initial conditions are set and the process cannot be batch-fed elements and microbial strains, and the gas cannot be collected in batches. Although significant results have been achieved in the coal-to-biogenic methane conversion in China, findings are restricted to the laboratory scale. No successful commercialization of coal bed biogenic methane production has been achieved yet. This study used a large-capacity fermentation tank (5 L) to conduct biogenic methane experiments. Results were compared to those from the traditional laboratory test. The gas production rate and gas concentration were higher when the 250 mL methane test volume was increased to a 5 L fermentation volume, increasing by 20.9% and 2.3%, respectively. The inhibition effect of the liquid phase products was reduced in the large fermentation tank, and the microbial activity was extended by batch feeding trace elements (iron and nickel) and methane strains and by semi-continuous collection of the gas. However, the gas conversion rate can be increased by retaining the H2 and CO2 in the intermediate gas products in the fermentation tank. The gas production rate was increased from 17.9 to 24.6 mL/g, increasing by 37.4%. The simulation pilot test can lay a foundation for the transition from a coal bed biogenic methane laboratory static small sample test to a dynamic pilot test, optimizing the process parameters to improve the reaction efficiency and move forward to commercialization test

Real-time Routes Design Research of DIY tour Based on Greedy Algorithm

Compared with group tour, DIY tour is characterized by flexible time arrangements and uncertain routes planning. This paper has mainly employed partial greedy algorithm based on time series in designing real-time routes in DIY tours. As restaurant and accommodation are featured by time window constraint, thus the design is divided into several time partitions in line with 24-hour clock, and each partition has its tour behaviors including sighting, restaurant and accommodation. In each partition and its joint, the paper has availed partial optimal strategy of greedy algorithm so as to complete the overall routes design

Highly parallel and efficient single cell mRNA sequencing with paired picoliter chambers

单细胞转录组测序技术在单个细胞水平上对转录组进行高通量测序分析，从而揭示单个细胞内所有基因的表达情况，揭示细胞间的异质性，在发育生物学、免疫学、微生物学、神经科学、临床医学等领域有重要的应用前景。单细胞转录组测序的挑战在于如何高效地操控单个细胞，如何对大量的低拷贝数mRNA进行无偏倚扩增，如何避免背景游离mRNA的污染，以及如何同时对大量的单细胞进行并行测序以降低成本。化学化工学院杨朝勇教授课题组在高通量单细胞转录组测序新器件新方法研究方面取得重要进展.该工作由厦门大学、上海交通大学、美国斯坦福大学等多团队联合攻关完成。化学生物学系博士研究生张明霞、邹远和2011协同创新中心博士研究生许醒为论文的共同第一作者。ScRNA-seq has the ability to reveal accurate and precise cell types and states. Existing scRNA-seq platforms utilize bead-based technologies uniquely barcoding individual cells, facing practical challenges for precious samples with limited cell number. Here, we present a scRNA-seq platform, named Paired-seq, with high cells/beads utilization efficiency, cell-free RNAs removal capability, high gene detection ability and low cost. We utilize the differential flow resistance principle to achieve single cell/barcoded bead pairing with high cell utilization efficiency (95%). The integration of valves and pumps enables the complete removal of cell-free RNAs, efficient cell lysis and mRNA capture, achieving highest mRNA detection accuracy (R = 0.955) and comparable sensitivity. Lower reaction volume and higher mRNA capture and barcoding efficiency significantly reduce the cost of reagents and sequencing. The single-cell expression profile of mES and drug treated cells reveal cell heterogeneity, demonstrating the enormous potential of Paired-seq for cell biology, developmental biology and precision medicine.The authors thank the National Science Foundation of China (21927806, 21735004, 21521004, 21325522), the National Key R&D Program of China (2018YFC1602900), Innovative research team of high-level local universities in Shanghai, and the Program for Changjiang Scholars and Innovative Research Team in University (IRT13036) for their financial support.该研究工作得到国家重大科研仪器研制项目、国家基金委重点项目、创新研究群体项目等支持

SAM-dPCR: Real-Time and High-throughput Absolute Quantification of Biological Samples Using Zero-Shot Segment Anything Model

Digital PCR (dPCR) has revolutionized nucleic acid diagnostics by enabling absolute quantification of rare mutations and target sequences. However, current detection methodologies face challenges, as flow cytometers are costly and complex, while fluorescence imaging methods, relying on software or manual counting, are time-consuming and prone to errors. To address these limitations, we present SAM-dPCR, a novel self-supervised learning-based pipeline that enables real-time and high-throughput absolute quantification of biological samples. Leveraging the zero-shot SAM model, SAM-dPCR efficiently analyzes diverse microreactors with over 97.7% accuracy within a rapid processing time of 3.16 seconds. By utilizing commonly available lab fluorescence microscopes, SAM-dPCR facilitates the quantification of sample concentrations. The accuracy of SAM-dPCR is validated by the strong linear relationship observed between known and inferred sample concentrations. Additionally, SAM-dPCR demonstrates versatility through comprehensive verification using various samples and reactor morphologies. This accessible, cost-effective tool transcends the limitations of traditional detection methods or fully supervised AI models, marking the first application of SAM in nucleic acid detection or molecular diagnostics. By eliminating the need for annotated training data, SAM-dPCR holds great application potential for nucleic acid quantification in resource-limited settings.Comment: 23 pages, 6 figure

DNAzyme crosslinked hydrogel: a new platform for visual detection of metal ions

We propose the use of DNAzyme as a crosslinker of hydrogel to develop a catalytic platform for the sensing of metal ions. The DNAzyme crosslinked hydrogel can undergo gel-sol transition in response to Cu(2+) ions, which enables sensitive visual detection of Cu(2+) by observing the release of pre-trapped AuNPs.National Basic Research Program of China[2010CB732402, 2007CB935603]; National Science Foundation of China[20805038, 21075104]; Natural Science Foundation of Fujian Province[2008J0107]; Natural Science Foundation of Fujian Province for Distinguished Young Scholar[2010J06004

Concurrent tolerance allocation and scheduling for complex assemblies

Traditionally, tolerance allocation and scheduling have been dealt with separately in the literature. The aim of tolerance allocation is to minimize the tolerance cost. When scheduling the sequence of product operations, the goal is to minimize the makespan, mean flow time, machine idle time, and machine idle time cost. Calculations of manufacturing costs derived separately using tolerance allocation and scheduling separately will not be accurate. Hence, in this work, component tolerance was allocated by minimizing both the manufacturing cost (sum of the tolerance and quality loss cost) and the machine idle time cost, considering the product sequence. A genetic algorithm (GA) was developed for allocating the tolerance of the components and determining the best product sequence of the scheduling. To illustrate the effectiveness of the proposed method, the results are compared with those obtained with existing wheel mounting assembly discussed in the literature