关节式电分相电磁暂态过程研究

关节式电分相是电气化铁路牵引供电系统较为薄弱的环节,电力机车在通过关节式电分相时经常会产生过电压现象,过电压可能会造成机车放电间隙击穿、牵引所馈线保护跳闸,严重影响铁路的安全运营.从实测结果来看,机车在过渡区和中性区行驶时过电压会持续存在一段时间,与以往对关节式电分相产生过电压的研究作对比,分析造成电磁暂态过程以及过电压延续的原因可能是机车的移动.在MATLAB/Simulink软件上建立了机车过关节式电分相的仿真模型,用多个离散过程来近似模拟机车过电分相的连续过程,最后与实测波形对比,验证等效模型是有效的.     

“两个一体化”战略下储能应用前景分析

储能对电能应用具有时序调节的作用,且储能技术在逐步完善,其应用场景也逐渐多元。在“风光水火储一体化”和“源网荷储一体化”（“两个一体化”）下,储能的灵活调节作用将得到更充分的发挥,储能有望迎来更广阔的发展空间。本文先对新能源领域相关政策以及“两个一体化”的建设规划概况进行梳理,然后分析了“两个一体化”下储能的灵活性以及经济性,研究了“两个一体化”下的储能规划,探究了“两个一体化”的商业化应用,提出了应因地制宜配置储能设施,储能收益多元,完善储能商业模式等建议,对今后储能的走向具有一定参考意义。     

锌铝镁镀层钢板前处理与电泳性能研究

以镀锌钢板作为对比,考察锌铝镁钢板涂装前处理和电泳性能.结果显示:锌铝镁钢板的脱脂性能与镀锌钢板相近,磷化膜外观、膜重、覆盖率和结晶尺寸与镀锌钢板差异较小,电泳漆膜外观、膜厚、附着力和耐冲击性与镀锌钢板一致,但电泳漆膜的杯突极限性能和划线循环腐蚀性能优于镀锌钢板.     

考虑寄生参数的隔离型双有源桥DC-DC变换器的开关开路故障分析与容错控制策略

双有源桥(DAB)DC-DC变换器开关管的驱动电路故障导致开关开路故障(OCSF),这使得DAB系统拓扑对称性缺失、高频电压和电流发生畸变和直流偏置,进而对系统的可靠性和长期运行稳定性造成不良影响.对此,研究DAB开关管和高频变压器寄生参数对OCSF后系统运行状态的影响,以完善DAB故障分析体系.针对OCSF问题,提出一种基于对称拓扑和对偶原理的故障容错策略,通过闭锁开关使系统运行拓扑恢复对称,并在此基础上提出一种不改变控制器参数、只需改变控制器输出饱和参数的实用控制方法,并在理论上讨论了该方法的可行性.最后,通过实验验证了OCSF模态分析及所提容错控制策略的正确性.     

A Dual Physical Cross-Linking Strategy to Construct Tough Hydrogels with High Strength,Excellent Fatigue Resistance,and Stretching-Induced Strengthening Effect

Hydrogels with excellent stiffness, toughness, anti-fatigue, and self-recovery properties are regarded as promising water-containing materials. In this work, a dual physically cross-linked (DPC) sodium alginate (SA)/poly[acrylamide (AAm)-acrylic acid (AAc)-octadecyl methacrylate (OMA)]-Fe³⁺ hydrogel is reported, which is constructed by hydrophobic association (HA) and ionic coordination (IC). The optimal DPC hydrogel demonstrates excellent mechanical performance: tensile modulus of 0.65 MPa, tensile strength of 3.31 MPa, elongation at break of 1547%, and toughness of 27.8 MJ m^–3. SA/P(AAm-AAc-OMA)-Fe³⁺ DPC hydrogels also exhibit prominent anti-fatigue and self-recovery performance (99.1–109.7% modulus recovery and 90.4–108.9% dissipated energy recovery after resting for 5 min without additional stimuli at ambient temperature) through the reconstruction of reversible physical cross-linking. Some of the SA/P(AAm-AAc-OMA)-Fe³⁺ DPC hydrogels even exhibit a stretching-induced strengthening effect, which is similar to the performance of muscle—“the more training, the more strength.” Hence, the combination of HA and IC will provide an effective approach to design DPC hydrogels with desirable mechanical performances and a longer service life for wider applications of soft materials.     

Zirconium-Embedded Polyhedral Oligomeric Silsesquioxane Containing Phosphaphenanthrene-Substituent Group Used as Flame Retardants for Epoxy Resin Composites

A zirconium hybrid polyhedral oligomeric silsesquioxane derivative (Zr–POSS–bisDOPO) is synthesized by the corner-capping and Kabachnik–Fields reactions. It is characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR), and then used as a flame retardant in diglycidyl ether of bisphenol A (DGEBA) to endow epoxy resin (EP) with flame retardancy. The flame retardancy, thermal stability, and mechanical properties of the cured EP/Zr–POSS–bisDOPO composites are investigated. The results show that when Zr–POSS–bisDOPO is added by 5–7 wt%, the EP/Zr–POSS–bisDOPO composites pass the UL-94 V-0 rating test. In addition, they have a better flame-retardant effect than pure EP. The combination of Zr atom embedded in the Si O cubic cage and the two phosphaphenanthrene substituent groups in one corner of cubic cage is expected to realize the Zr/Si/P ternary intramolecular hybrid synergistic effect and achieve the possibility of dispersing metal–POSS cages at a sub-micrometer-scale level into polymer matrix. It also proves that Zr–POSS–bisDOPO produces phosphorus-containing free radicals and terminates the chain reactions in gas phase. Meanwhile the Si O Si and Zr O units are retained in the solid phase, which promote the char formation and enhance the flame retardancy. This kind of Zr-doped POSS will be helpful for developing the new metal–POSS hybrid flame-retardant and polymer composites.     

Hypoxia/Temperature/pH Triple Stimuli–Responsive Block Copolymers: Synthesis,Self-Assembly,and Controlled Drug Release

The amphiphilic block copolymer poly(methacrylic acid-co-2-nitroimidazole acrylate)-b-poly(2-(N,N-dimethylamino)ethyl methacrylate) (P(MAA-co-NIMA)-b-PDMAEMA) with the hypoxia/temperature/pH triple responsiveness is synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT), hydrolysis, and 3-(3-dimethylaminopropyl)-1-ethylcarbodiimide (EDC) reactions, and successfully self-assembled into micelles. The hypoxia response in vitro is realized, and then the sensitivity of the self-assembled micelles to the hypoxia condition is studied by controlling the grafting amount of aminated 2-nitroimidazole. Because 2-(N,N-dimethylamino) ethyl methacrylate (DMAEMA) is a typical material sensitive to temperature and pH conditions, the self-assembled micelles are also responsive to temperature and different acidic/basic conditions. In addition, the cumulative release rate of doxorubicin (DOX) at 42 °C, pH = 6.0, and hypoxic conditions increases significantly, and verifies the synergistic promotion effect of the above stimulations. This intelligent polymer with triple response mechanism improves the controllability and efficiency of drug release, and is expected to be a drug carrier for cancer treatment.     

3D Printing Conductive Composites with Poly(ionic liquid) as a Noncovalent Intermedia to Fabricate Carbon Circuits

In this study, a kind of imidazole type poly(ionic liquid) ([PEP-MIM]Cl) is synthesized, which can disperse carbon effectively. [PEP-MIM]Cl is used as an intermediate to coat carbon on the poly(acrylic acid)(PAA-co-MBA) via ion exchange to obtain conductive polymer composite (CPC). A series of characterizations are performed. Experiments show that carbon can be coated on the PAA-co-MBA uniformly, and compared with using carbon as filler, this method requires less carbon to achieve good conductive performance. The carbon layer on the polymer's surface is enriched via the swelling-shrinking properties of PAA-co-MBA according to the SEM images. Furthermore, in combination with 3D printing technology, PAA-co-MBA can be designed into different shapes to achieve various functions such as pressure-sensing element. Finally, a new type of CPC named carbon clad polymeric laminate (CCPL) is prepared by using the carbon coating method and 3D printing technology. It has the potential to replace copper clad laminate (CCL) and printed circuit board (PCB), to a certain extent. This technology expands the preparation method and application of the CPC such as flexible and wearable conductive fabrics.     

Supplementation with Docosahexaenoic Acid and Vitamin E Improves Hepatic Triglyceride Accumulation Induced by High-Fat Diet in Mice

The study aims to investigate the effect of combined supplementation with docosahexaenoic acid (C22:6 n-3, DHA) and vitamin E (VE) on the oxidative stress and liver triglycerides (TG) accumulation induced by high-fat diet (HFD) in mice. C57BL/6J mice are fed either a control diet or an HFD for 8 weeks. Animals are supplemented with DHA, VE, or DHA + VE, respectively. Supplementation with DHA alone shows significant improvement in oxidative stress and hepatic steatosis in mice. Supplementation with DHA significantly reduces the liver TG and total cholesterol contents, and the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, compared with the HFD. Supplementation with DHA also significantly decreases the mRNA expression level of sterol regulatory element-binding protein 1C. However, supplementation with VE alone does not show improvement in oxidative stress and hepatic steatosis. DHA + VE supply obtains a superior effect in alleviation of hepatic steatosis than DHA supplementation alone in mice fed by HFD. The efficacy of DHA potentiated by VE can be due to that VE enhances the effect of DHA in decrease of ALT and AST levels and increase of antioxidant enzyme activity and glutathione level in mice fed by HFD. Practical Applications: Supplementation with DHA significantly improves the oxidative stress and hepatic steatosis induced by HFD in mice. The efficacy of DHA in the alleviation of hepatic steatosis induced by HFD is potentiated by VE. These findings may provide a rational basis for the use of DHA and VE co-supplementation in patients with liver steatosis.     

Preparation and Bioactivity of Iridium(III) Phenanthroline Complexes with Halide Ions and Pyridine Leaving Groups

A series of half-sandwich structural iridium(III) phenanthroline (Phen) complexes with halide ions (Cl⁻, Br⁻, I⁻) and pyridine leaving groups ([(η⁵-Cp^X)Ir(Phen)Z](PF₆)_n, Cp^x: electron-rich cyclopentadienyl group, Z: leaving group) have been prepared. Target complexes, especially the Cp^xbiph (biphenyl-substituted cyclopentadienyl)-based one, showed favourable anticancer activity against human lung cancer (A549) cells; the best one ( Ir8 ) was almost five times that of cisplatin under the same conditions. Compared with complexes involving halide ion leaving groups, the pyridine-based one did not display hydrolysis but effectively caused lysosomal damage, leading to accumulation in the cytosol, inducing an increase in the level of intracellular reactive oxygen species and apoptosis; this indicated an anticancer mechanism of oxidation. Additionally, these complexes could bind to serum albumin through a static quenching mechanism. The data highlight the potential value of half-sandwich iridium(III) phenanthroline complexes as anticancer drugs.