柴油机相继增压切换过程阀门耦合控制研究

为解决相继增压系统切换过程中压气机喘振和倒流问题,建立了GT-Power/Simulink相继增压系统耦合仿真计算模型,并对切换过程压气机动作延迟时间的影响规律进行研究。仿真结果表明:压气机延迟关闭可以避免压气机的喘振现象;压气机延迟开启可以避免压气机的倒流现象。合理的阀门控制策略可以使切换过程增压压力的波动减少9.3%～21.6%。     

Multi-stage intelligent operation optimization for a hydrocracking fractionation system with a multi-fractionator series-parallel structure

A fractionation system is an essential unit in the hydrocracking process. Its optimal operation is challenging because of the complexity in the structure of the distillation tower and composition of the stream. In addition, the series-parallel structure between the distillation towers of different techniques aggravates the coupling and complexity of the hydrocracking fractionation system (HFS). This, in turn, increases the time complexity of the optimization problem. In this paper, a rigorous mechanism model of an actual HFS is first applied to describe the operating conditions of the HFS. Then, an improved state transition algorithm (STA) with a staged evaluation strategy is proposed to solve the above problem. To overcome problems caused by the series-parallel structure of HFS, the model is divided into multiple stages for evaluation by mechanism analysis. Furthermore, several typical convergence estimation criteria are introduced to reduce unnecessary model calculations. To solve time-consuming problems associated with HFS optimization, the adaptive change operator is used to improve the search function of the original algorithm and two performance criteria are presented to reduce the optimization time. The proposed algorithm is successfully applied to the operational parameter optimization problem of HFS with a multi-fractionator series-parallel structure. The experimental results indicated that the staged evaluation strategy improved the fast convergence probability of the HFS mechanism model and reduced unnecessary calculations, whereas the improved algorithm increased accuracy and significantly decreased optimization time.     

Simplified anode architecture for PEMFC systems based on alternative fuel feeding: Experimental characterization and optimization for automotive applications

The need to reduce PEMFC systems cost as well as to increase their durability is crucial for their integration in various applications and especially for transport applications. A new simplified architecture of the anode circuit called Alternating Fuel Feeding (AFF) offers to reduce the development costs. Requiring a new stack concept, it combines the simplicity of Dead-End Anode (DEA) with the operation advantages of the hydrogen recirculation. The three architectures (DEA, recirculation and AFF) are compared in terms of performance on a 5-kW test bench in automotive conditions, through a sensitivity analysis. A gain of 17% on the system efficiency is observed when switching from DEA to AFF. Moreover, similar performances are obtained both for AFF and for recirculation after an accurate optimization of the AFF tuning parameters. Based on DoE data, a gain of 25% on the weight of the anodic line has been identified compared to pulsed ejector architecture and 43% with the classic recirculation architecture with blower only (Miraï).     

1 200 MPa级冷轧先进高强钢轧制稳定性的分析及控制

针对1 200 MPa级冷轧先进高强钢轧制不稳定问题,对热轧原料组织性能均匀性、冷轧压缩比、冷连轧机组轧制策略等进行了分析。结果表明,热轧工序投入边部加热器,采用分段冷却等手段,可有效降低热轧原料头尾部组织性能差异,保证通卷性能均匀,进而保证通卷轧制过程稳定;通过优化冷连轧机组压缩比,可有效降低材料本身的加工硬化强度,进而避免连轧机组后面机架的轧制超负荷情况;通过优化冷连轧机组轧制策略,可保证轧制过程中各机架均匀变形,避免出现轧制力差异较大的情况,进而保证轧制过程稳定。采用上述措施,1 200 MPa级冷轧先进高强钢轧制力控制在约15 000 kN,厚度精度控制在±0.06 mm以内,可保证该级别高强钢的稳定轧制。     

A hover view over Australia's Hydrogen Industry in recent history: The necessity for a Hydrogen Industry Knowledge-Sharing Platform

The hydrogen industry in Australia has gained tremendous momentum in 2018 and after the publishing of the National Hydrogen Roadmap. In this study, a comprehensive review of the recent history of hydrogen-related activities and publications, as well as hydrogen funding programs and the funded projects, was conducted. Most of these activities were tabulated and discussed from the perspective of sorting, documentation, and contrast. The broad picture indicates the need and necessity of a unified national database for the hydrogen industry landscape. An innovative modular online (web-based) crowdsourced database platform is introduced in this paper as the “Australia Hydrogen Industry Knowledge-Sharing Platform” to include all hydrogen-related activities in Australia. This web-based platform will be presented in the form of a business to generate revenue to offset operation and maintenance costs and ensure the system updating. This study will not only guide the Australian governments and/or stakeholders to develop a hydrogen economy for the future but also other countries to promote their hydrogen industry.     

计算机网络办公自动化及安全策略探究

互联网通讯采取标准化模式主要以TCP/IP协议为载体,通讯的优越特性体现在同时具备便捷性与开放性,为办公提供很大的便利,但基于网络系统也会入侵病毒、也会给信息数据与办公体系安全性造成威胁,直接影响企业综合稳定发展。据此,为保障办公工作的顺利开展,本文对计算机网络办公自动化及安全策略进行详细分析。     

Fast and stable operation approach of ship solid oxide fuel cell-gas turbine hybrid system under uncertain factors

This work focuses on investigating the adaptability of solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system for ship application under uncertain factors. The effect of rapids, wind and waves on the performance of ship SOFC-GT is analyzed. In addition, a novel control system combining fuzzy logic theory, temperature feedforward and coordination factor on-line adjustment is proposed to address the problem of load disturbances caused by uncertain factors. The results show that the proposed operation strategy can shorten the thermal response time inside fuel cell stacks by almost 49.97%, meanwhile, reducing the maximum temperature changing rate at the electrochemically active tri-layer cell composed of anode, electrolyte, and cathode (PEN structure) by around 17.86%. Moreover, the reasonable matching between air flow and fuel flow is an essential prerequisite to ensure the safe and efficient operation of ship SOFC-GT. While the SOFC-GT is working at full load, the results indicate that the fuel to air ratio cannot exceed 2.56?10^?2 g/g. Finally, an application scenario of the 5000-ton river-to-sea cargo ship sails from Nanjing Port to Yangshan Port (Eastern China) is conducted to analyze the operation characteristics of ship SOFC-GT under uncertain factors. Two set of 1000 kW SOFC-GT systems with the electrical efficiency of 64.66% is designed for the target ship, the results conclude that the operation strategy of each SOFC-GT system supports 50% load is beneficial in reducing the power tracking time and SOFC temperature overshoot. The average electrical efficiency of 61.45% and 61.04% are achieved in winter and summer typical days respectively in the whole voyage.     

High lithium storage of Co3O4 enabled by integrating hollow and porous carbon scaffolds

The Co₃O₄, as a potential anode of lithium-ion batteries, has gained considerable attention because of high theoretical capacity. However, the Co₃O₄ is suffering from serious structure deterioration and rapid capacity fading due to its bulky volume change during cyclic charge/discharge process. Herein, to stabilize the lithium storage performance of the Co₃O₄ nanoparticles, a characteristic carbon scaffold (HPC) integrating hollow and porous structures has been fabricated by a well-designed method for the first time. The ultrafine Co₃O₄ nanoparticles are cleverly anchored on the HPC (HPC@Co₃O₄) and hence achieve significantly improved electrochemical properties including high capacity, improved reaction kinetics and outstanding cycle stability, showing high capacity of 1084.7 mAh g^-1 after 200 cycles at 200 mA g^-1 as well as 681.4 mAh g^-1 after 300 cycles at 1000 mA g^-1. The HPC@Co₃O₄ therefore shows good promising for application in advanced lithium-ion battery anodes. The results of the systematically material and electrochemical characterizations indicate that the synergistic effects of ultrafine Co₃O₄ nanoparticles and well-designed HPC scaffolds are responsible for the outstand performance of the HPC@Co₃O₄ anode. Moreover, this work can enrich the understanding and development of stable and high-performance metal oxide-based lithium-ion battery anodes for advanced lithium storage.     

磁流变减振器魔术公式模型在悬架控制中的应用

基于某款磁流变减振器特性实验数据，辨识了磁流变减振器魔术公式模型的各项参数，模型误差在8%以内。在适当简化磁流变减振器魔术公式模型的条件下，通过直接逆推得到磁流变减振器魔术公式逆模型。仿真中，磁流变减振器魔术公式正、逆模型实现加速度驱动阻尼控制策略期望阻尼力的误差平均值为3.67%。台架实验中，磁流变减振器魔术公式逆模型的应用使车身加速度降低了6.27%，实现了加速度驱动阻尼控制策略的控制效果。磁流变减振器魔术公式模型在半主动控制悬架系统仿真及台架实验中的成功应用对磁流变半主动悬架控制系统的研究有较强的实际意义。     

A Biomimetic Hybrid Hydrogel Based on the Interactions between Amino Hydroxyapatite and Gelatin/Gellan Gum

In this work, a gelatin (Gel)‐oxidized gellan gum (OG)/amino hydroxyapatite (mHap) hybrid hydrogel with Schiff base linkages is reported. The mHap is obtained by modifying hydroxyapatite with tetraethyl orthosilicate and 3‐aminopropyl‐triethoxysilane. The effects of different mHap contents on the structure, morphology, and properties of hydrogels are particularly investigated. Scanning electron microscopy coupled with energy dispersion spectroscopy reveals that mHap of around 100 nm is uniformly distributed inside the hydrogel with interconnected porous structures. Notably, the hydrogel with 1 wt% mHap possesses the highest compressive stress (2.01 ± 0.10 MPa) at 90% strain, as well as the lowest equilibrium swelling ratio (97% ± 5%) and degradation rate than other hydrogels. Besides, an ultra‐high compressive stress equivalent to 91% of the initial stress can be obtained by this hydrogel after 50 loading‐unloading cycles (85% strain). Meanwhile, after being swollen, this improved hydrogel also exhibits better structural stability than Gel‐OG hydrogel. The in vitro 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay further shows that all hydrogels are nontoxic against mouse fibroblasts. This work provides a biomimetic strategy to construct the organic/inorganic hydrogels with excellent interactions, elasticity, reversibility, and biocompatibility, which is of great importance for the practical applications in cartilage tissue engineering.