中间母线变换器(Intermediate Bus Converter,简称IBC)由于其特殊的结构和功能,对效率要求较高。本文采用一种特殊结构,利用变压器漏感与谐振电容的谐振来控制主开关管的开断,实现了初级主开关管的软开关,提高了变换器的效率。首先,通...中间母线变换器(Intermediate Bus Converter,简称IBC)由于其特殊的结构和功能,对效率要求较高。本文采用一种特殊结构,利用变压器漏感与谐振电容的谐振来控制主开关管的开断,实现了初级主开关管的软开关,提高了变换器的效率。首先,通过对电路开关模态的研究,详细分析了电路工作原理,然后用Saber软件进行了仿真,最后根据理论及仿真分析设计并研制了一台输入为36～60V,输出为8～12V的250W/280kHz的原理样机。测得额定输入48V,输出9V条件下的效率高达96%。从实验和仿真波形及效率测试等几个方面验证了变换器软开关的实现。分析得出,该变换器的软开关条件与输入输出条件无关,不同于传统的软开关拓扑,易于产品化,有一定的应用价值。展开更多
In this paper, a new transformation is introduced to solve triple sine-Gordon equation. It is shown that this intermediate transformation method is powerful to solve complex special type nonlinear evolution equation.
A new method based on the material removal and cross-section optical scanning is investigated.The advantage of this method is that the internal and external information of the specimen can be obtained at same precisio...A new method based on the material removal and cross-section optical scanning is investigated.The advantage of this method is that the internal and external information of the specimen can be obtained at same precision. In order to eliminate the pulse and Gaussian noise, the multi-scale dyadic wavelet methods are presented and discussed. The experimental results show that the multi-scale dyadic wavelet methods can successfully extract the features from noise image.The accuracy of 2D edge detection is 5.4 μm with the resolution of 2.7 μm.展开更多
Ethylene tar pitch was co-carbonized with waste polystyrene to prepare mesophase pitch. The character- istics of mesophase pitches were examined using polarized light optical microscopy, apparent viscome- try, Fourier...Ethylene tar pitch was co-carbonized with waste polystyrene to prepare mesophase pitch. The character- istics of mesophase pitches were examined using polarized light optical microscopy, apparent viscome- try, Fourier transform infrared spectrometry, IH nuclear magnetic resonance spectrometry, and X-ray diffractometry. The properties of the mesophase pitch were greatly improved because of the eutectic effect. The soluble content increased from 5% to 56%, the mesophase itself increased from 32% to 100%, and the optical texture was changed from a coarse mosaic into a flow domain after the waste polystyrene was added to the ethylene tar pitch. The apparent viscosity showed that the mesophase pitch changed from thixotropic to Newtonian suggesting improved rheological behavior during co-carbonization）The increased number of alkyl groups, which are mainly methylene groups, altered the molecular structure of the mesophase pitch in a way that resulted in the eutectic effect.展开更多
The pyrolysis of different waste polymers （polyethylene, polypropylene and polystyrene） was investigated in a tube reactor at 550 ℃ in the absence of oxygen. Additionally the energetic utilization of products have ...The pyrolysis of different waste polymers （polyethylene, polypropylene and polystyrene） was investigated in a tube reactor at 550 ℃ in the absence of oxygen. Additionally the energetic utilization of products have also been followed both in refining and petrochemical industry. Pyrolysis products were separated into fractions of gases, naphtha, middle distillates and heavy oil. Raw materials have been collected both from industrial and household sources： polyethylene from agriculture, polyethylene from packaging and polystyrene from packaging and electronic equipments. Yields and properties of volatile products have changed by the raw materials. Products have been analyzed by gas chromatography. Fourier transformed infrared spectroscopy, size exclusion chromatography and other standardized methods. Naphtha had high octane numbers （80 〈 RON）, while high cetane numbers （〉 75） in case of middle distillates. Moreover fractions contained approximately half of unsaturated hydrocarbons, mainly α-olefins, but the percentage was depending on the raw materials. These properties are advantageous for fuel-like applications.展开更多
文摘中间母线变换器(Intermediate Bus Converter,简称IBC)由于其特殊的结构和功能,对效率要求较高。本文采用一种特殊结构,利用变压器漏感与谐振电容的谐振来控制主开关管的开断,实现了初级主开关管的软开关,提高了变换器的效率。首先,通过对电路开关模态的研究,详细分析了电路工作原理,然后用Saber软件进行了仿真,最后根据理论及仿真分析设计并研制了一台输入为36～60V,输出为8～12V的250W/280kHz的原理样机。测得额定输入48V,输出9V条件下的效率高达96%。从实验和仿真波形及效率测试等几个方面验证了变换器软开关的实现。分析得出,该变换器的软开关条件与输入输出条件无关,不同于传统的软开关拓扑,易于产品化,有一定的应用价值。
文摘In this paper, a new transformation is introduced to solve triple sine-Gordon equation. It is shown that this intermediate transformation method is powerful to solve complex special type nonlinear evolution equation.
文摘A new method based on the material removal and cross-section optical scanning is investigated.The advantage of this method is that the internal and external information of the specimen can be obtained at same precision. In order to eliminate the pulse and Gaussian noise, the multi-scale dyadic wavelet methods are presented and discussed. The experimental results show that the multi-scale dyadic wavelet methods can successfully extract the features from noise image.The accuracy of 2D edge detection is 5.4 μm with the resolution of 2.7 μm.
基金the financial support by the Fundamental Research Funds for the Central Universities (No.2010QNA14)
文摘Ethylene tar pitch was co-carbonized with waste polystyrene to prepare mesophase pitch. The character- istics of mesophase pitches were examined using polarized light optical microscopy, apparent viscome- try, Fourier transform infrared spectrometry, IH nuclear magnetic resonance spectrometry, and X-ray diffractometry. The properties of the mesophase pitch were greatly improved because of the eutectic effect. The soluble content increased from 5% to 56%, the mesophase itself increased from 32% to 100%, and the optical texture was changed from a coarse mosaic into a flow domain after the waste polystyrene was added to the ethylene tar pitch. The apparent viscosity showed that the mesophase pitch changed from thixotropic to Newtonian suggesting improved rheological behavior during co-carbonization）The increased number of alkyl groups, which are mainly methylene groups, altered the molecular structure of the mesophase pitch in a way that resulted in the eutectic effect.
文摘The pyrolysis of different waste polymers （polyethylene, polypropylene and polystyrene） was investigated in a tube reactor at 550 ℃ in the absence of oxygen. Additionally the energetic utilization of products have also been followed both in refining and petrochemical industry. Pyrolysis products were separated into fractions of gases, naphtha, middle distillates and heavy oil. Raw materials have been collected both from industrial and household sources： polyethylene from agriculture, polyethylene from packaging and polystyrene from packaging and electronic equipments. Yields and properties of volatile products have changed by the raw materials. Products have been analyzed by gas chromatography. Fourier transformed infrared spectroscopy, size exclusion chromatography and other standardized methods. Naphtha had high octane numbers （80 〈 RON）, while high cetane numbers （〉 75） in case of middle distillates. Moreover fractions contained approximately half of unsaturated hydrocarbons, mainly α-olefins, but the percentage was depending on the raw materials. These properties are advantageous for fuel-like applications.
