In Situ Exfoliated,Edge‐Rich,Oxygen‐Functionalized Graphene from Carbon Fibers for Oxygen Electrocatalysis

Metal‐free electrocatalysts have been extensively developed to replace noble metal Pt and RuO₂ catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in fuel cells or metal–air batteries. These electrocatalysts are usually deposited on a 3D conductive support (e.g., carbon paper or carbon cloth (CC)) to facilitate mass and electron transport. For practical applications, it is desirable to create in situ catalysts on the carbon fiber support to simplify the fabrication process for catalytic electrodes. In this study, the first example of in situ exfoliated, edge‐rich, oxygen‐functionalized graphene on the surface of carbon fibers using Ar plasma treatment is successfully prepared. Compared to pristine CC, the plasma‐etched carbon cloth (P‐CC) has a higher specific surface area and an increased number of active sites for OER and ORR. P‐CC also displays good intrinsic electron conductivity and excellent mass transport. Theoretical studies show that P‐CC has a low overpotential that is comparable to Pt‐based catalysts, as a result of both defects and oxygen doping. This study provides a simple and effective approach for producing highly active in situ catalysts on a carbon support for OER and ORR.     

Few Atomic Layered Lithium Cathode Materials to Achieve Ultrahigh Rate Capability in Lithium‐Ion Batteries

The most promising cathode materials, including LiCoO₂ (layered), LiMn₂O₄ (spinel), and LiFePO₄ (olivine), have been the focus of intense research to develop rechargeable lithium‐ion batteries (LIBs) for portable electronic devices. Sluggish lithium diffusion, however, and unsatisfactory long‐term cycling performance still limit the development of present LIBs for several applications, such as plug‐in/hybrid electric vehicles. Motivated by the success of graphene and novel 2D materials with unique physical and chemical properties, herein, a simple shear‐assisted mechanical exfoliation method to synthesize few‐layered nanosheets of LiCoO₂, LiMn₂O₄, and LiFePO₄ is used. Importantly, these as‐prepared nanosheets with preferred orientations and optimized stable structures exhibit excellent C‐rate capability and long‐term cycling performance with much reduced volume expansion during cycling. In particular, the zero‐strain insertion phenomenon could be achieved in 2–3 such layers of LiCoO₂ electrode materials, which could open up a new way to the further development of next‐generation long‐life and high‐rate batteries.     

Unraveling the Solution‐State Supramolecular Structures of Donor–Acceptor Polymers and their Influence on Solid‐State Morphology and Charge‐Transport Properties

Polymer self‐assembly in solution prior to film fabrication makes solution‐state structures critical for their solid‐state packing and optoelectronic properties. However, unraveling the solution‐state supramolecular structures is challenging, not to mention establishing a clear relationship between the solution‐state structure and the charge‐transport properties in field‐effect transistors. Here, for the first time, it is revealed that the thin‐film morphology of a conjugated polymer inherits the features of its solution‐state supramolecular structures. A “solution‐state supramolecular structure control” strategy is proposed to increase the electron mobility of a benzodifurandione‐based oligo(p‐ phenylene vinylene) (BDOPV)‐based polymer. It is shown that the solution‐state structures of the BDOPV‐based conjugated polymer can be tuned such that it forms a 1D rod‐like structure in good solvent and a 2D lamellar structure in poor solvent. By tuning the solution‐state structure, films with high crystallinity and good interdomain connectivity are obtained. The electron mobility significantly increases from the original value of 1.8 to 3.2 cm² V^?1 s^?1. This work demonstrates that “solution‐state supramolecular structure” control is critical for understanding and optimization of the thin‐film morphology and charge‐transport properties of conjugated polymers.     

通用交直流传动系统CAD软件包的系统辨识功能

本文以通用交直流传动系统CAD软件包为背景,引入分数时滞模型及其辨识方法,分别辨识交直流传动系统的离散模型,并能求得其对应的连续模型,这为利用工程设计方法,自适应地设计控制器提供了方便。另外,本软件包所提供的方便的图形界面,明显的辨识结果比较,也为自动控制系统工程设计方法的学习提供了很好的CAI手段。     

锅炉四管爆漏专家系统的不确定知识处理

对锅炉四管爆漏专家系统的不确定知识进行分析,提出按主观Bayes方法建立计算模型,并作了简化技术处理,使专家系统具有不确定知识推理能力。     

Quantitative analysis of double-stranded DNA amplified by a polymerase chain reaction employing surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) was utilized for the quantitative analysis of double-stranded (ds) DNA amplified by a polymerase chain reaction (PCR). 4?, 6-Diamidino-2-phenylindole dihydrochloride (DAPI), which intercalates into ds-DNA but does not form a complex with single-stranded (ss) DNA, was added to a DNA solution after amplification by PCR. When the solution was mixed, including ds-DNA-DAPI complexes and free DAPI with silver colloid sol, only free DAPI was adsorbed on the colloid surface. The dye on the colloid gave very intense SERS signals with excitation at 514.5 nm, whereas DAPI engaging in the intercalation with ds-DNA did not show any SERS signal. The SERS spectrum of DAPI on the colloid showed a strong band at 1610 cm(-1) due to the C?N stretching mode, and a linear relationship was observed between the peak intensity of the C?N stretching band and the concentration of free DAPI. Therefore one can determine the concentration of free DAPI by the SERS measurement. The more ds-DNA there is in the solution, the less free DAPI there is. Thus it is possible to quantitatively analyze the ds-DNA amplified by PCR indirectly by using SERS. The correlation coefficient between the peak intensity of the C?N stretching band and the concentration of ds-DNA amplified by PCR was calculated to be 0.988 for a concentration range from 0.1 to 1.3 mg/ml.     

涂层织物的拉伸性能

本文通过电子双轴向拉伸试验机,对涂层积物的拉伸性能进行了系统研究,并得出了一系列重要结果。由于研究了涂层积物拉伸断裂曲线的特性,因而对于分析基布与涂层积物间的关系,对加工工艺过程中如何选择基布和涂层膜的类型等均有所论及。     

Robust control of multistage printing systems

Printing errors (e.g. doubling) in multistage printing machines are mainly caused by web tension fluctuations, which arise from excessive rotation non-synchronization errors among the driven rollers in different stages (units). Therefore, the critical task in printing quality control is to attenuate web tension variations. In this paper, a robust H_∞ control strategy is proposed to attenuate tension fluctuations when the system is subject to disturbances and variations in speed or other operating conditions. Three system robustness properties are analyzed by using structured singular value analysis (μ-analysis). A systematic investigation is taken to analyze the impacts of different parameter variations on system robustness, with a purpose of providing a reference for achieving robust stability in a multistage printing system. The effectiveness of the proposed robust H_∞ controller is evaluated by both simulation and experimental tests.     

A collaborative scheduling approach for service-driven scientific workflow execution

Scientific workflow execution often spans multiple self-managing administrative domains to obtain specific processing capabilities. Existing (global) analysis techniques tend to mandate every domain-specific application to unveil all private behaviors for scientific collaboration. In practice, it is infeasible for a domain-specific application to disclose its process details (as a private workflow fragment) for privacy or security reasons. Consequently, it is a challenging endeavor to coordinate scientific workflows and its distributed domain-specific applications. To address this problem, we propose a collaborative scheduling approach that can deal with temporal dependencies between a scientific workflow and a private workflow fragment. Under this collaborative scheduling approach, a private workflow fragment could maintain the temporal consistency with a scientific workflow in resource sharing and task enactments. Further, an evaluation is also presented to demonstrate the proposed approach for coordinating multiple scientific workflow executions in a concurrent environment.