Performance characteristics and optimization theory of the novel fuel cell hybrid systems

近年来，日益枯竭的化石能源和日益严重的环境污染已成为世界经济和社会发展的最大障碍之一，所以大力发展可再生新能源、走可持续发展道路已成为各国政府关注的重大战略问题。加大燃料电池及其混合系统的研究力度，提高燃料电池及其混合系统的能量转换效率，有效地开发利用氢能等清洁能源是人类的战略能源发展方向之一。本文以现有的多种燃料电池、热机以及三热源循环为基础，深入探索一些典型燃料电池的性能特性，构建新颖的燃料电池混合系统，优化设计系统的性能参数，建立优化理论，相关的研究内容安排在第二至第六章。 在第二章中，首先研究工作在稳定态下的质子交换膜燃料电池的一般性能特性，确定了主要性能参数的最优判据。进而为了有效...In the last years, the more and more exhausted fossil fuels and serious environmental pollution have become one of the biggest barriers for the development of world economy and society, so exploiting renewable energy sources and carrying out sustainable development are important strategic issues for every country government. Enhancing the research and improving the energy conversion efficiency of ...学位：理学博士院系专业：物理与机电工程学院物理学系_理论物理学号：1982009015366

嗜虫耶尔森氏菌HlyA及HasA外分泌表达系统的构建

【目的】构建一株具备外分泌蛋白功能的工程菌,解决杀虫毒素无法由胞内分泌至胞外,无法直接作用于虫体等问题,为松墨天牛防治提供新思路。【方法】本研究先测定从松墨天牛肠道及其生境中分离出的嗜虫耶尔森氏菌(CSLH88)的生长特性及抗性,进而对其进行分子改造。构建HlyA (pGHKW2)以及HasA (pGHKW4)外分泌表达载体,利用电穿孔法将其转入CSLH88菌株,获得能够表达绿色荧光蛋白的工程菌。利用稀释涂板及荧光体式镜检测技术对两个质粒进行遗传稳定性检测,并采用SDS-PAGE及Western blotting技术验证蛋白外分泌功能。【结果】CSLH88菌株培养2–4 h能够进入对数生长期,并对卡那霉素(Kan)敏感。成功构建了含有Kan抗性基因的pGHKW2(GenBank:MK562405)和pGHKW4(GenBank:MK562404)两个外分泌表达载体的CSLH88工程菌株。其中,发现pGHKW4质粒更加适合在嗜虫耶尔森氏菌中稳定遗传。SDS-PAGE及Western blotting检测结果表明HlyA系统无法在CSLH88菌株中将目的蛋白分泌到胞外,而HasA系统则可以有效地发挥外分泌表达功能。【结论】通过对HlyA及HasA两个外分泌表达系统进行研究,从中筛选出HasA型血红素转运系统作为CSLH88菌株的外分泌表达系统,为后续外分泌杀虫毒素蛋白菌株构建以及CSLH88菌株的致病性研究奠定基础。国家重点研发计划课题(2017YFD0600105);;\n国家自然科学基金(31601905);;\n福建省科技厅自然科学基金(2016J01097);;\n福建省科技计划项目(2018N5002);;\n福建农林大学科研基金(xjq201614);福建农林大学林学院林学高峰学科项目(71201800720,71201800753,71201800779);;\n福建省大学生创新创业训练计划项目(201810389102);;\n福建省林业科学研究项目[Minlinke(2017)03]~

PERFORMANCE ANALYSIS AND PARAMETRIC OPTIMIZATION of A TWO-STAGE IRREVERSIBLE MAGNETIC BRAYTON REFRIGERATION CYCLE

建立受有限速率热传导和绝热过程不可逆性影响的二级磁brAyTOn制冷循环模型,导出循环的性能系数和制冷率表达式,分析等磁场过程的磁场比、绝热不可逆因子、等磁中冷过程等对二级不可逆磁brAyTOn制冷循环最大制冷率及相关参数的影响,所得结论能为提高磁制冷机的循环性能提供参数设计参考。A two-stage magnetic Brayton refrigeration cycle model affected by finite-rate heat transfer and irreversibility in the adiabatic processes is established.The analytical expressions of the coefficient of performance and cooling rate for the refrigeration cycle are derived.The influences of the ratio of the magnetic field intensities in the iso-magnetic field processes,irreversible adiabatic factors, and iso-magnetic field inter-cooling process on the maximum cooling rate and the corresponding performance parameters of the cycle are analyzed and discussed.The results obtained here may provide some references to enhancement of the cycle performance and optimal design of the operating parameters of magnetic refrigerators.国家自然科学基金(No.50776074

Structural and electronic properties of T-graphene and its derivatives

采用基于密度泛函理论的第一原理方法研究了T型石墨烯及其衍生物-n(n=1-5)的结构稳定性和电子结构性质.T型石墨烯是一种拥有四角形环的二维碳材; 料同素异构体,通过改变连接四角形环的碳链上的碳原子个数n,可以得到一系列的sp-sp~2杂化结构,称其为T型石墨烯衍生物-n.计算结果表明:这些; 材料的结构稳定性、化学键类型和电子结构性质都依存于n的奇偶性.其中T型石墨烯(n=0)的结构最稳定,并形成一个由8个碳原子构成的大环.声子谱计算; 的结果表明,n为偶数时的体系具有动力学稳定性,而n为奇数时的体系则是不稳定的.n为偶数时体系四角形环之间的碳链上的化学键呈单、三键交叉排列,体系; 显示为金属性特征,且随着n的增大,体系的金属性加强.n为奇数时体系四角形环之间的碳链上的化学键则为双键连续排列,体系呈金属性且具有磁性(n=1除; 外).研究表明该系列材料作为一种新的二维碳材料同素异构体,具有独特的结构和丰富的电子结构特性,很可能在纳米器件中得到广泛应用.Recent years there has been aroused a growing interest in designing two-dimensional (2D) structures of carbon allotropes, owing to the great success in graphene. The T-graphene is a newly proposed 2D carbon allotrope possessing tetragonal symmetry other than hexagonal symmetry of graphene. Also, the energetic and dynamical stabilities of T-graphene have been revealed. So motivated, we investigate the structural stabilities and electronic properties of T-graphene and especially its derivatives-n (n = 1-5) by using the first-principle calculation based on the density function theory. By changing the atomic number (n) of the linear carbon chains connecting the two tetragon rings of T-graphene, a series of sp-sp 2 hybrid structures can be formed, which is named T-graphene derivatives-n. The calculation results show that the structural stabilities, chemical bond types and electronic structures of these materials depend greatly on the parity of n. Owing to a strong pi-bond formed by eight carbon atoms in T-graphene, it becomes the one with the lowest energy in all these materials studied in this work. An interesting phenomenon is found that the T-graphene derivatives-n with even n are dynamically stable as witnessed by the calculated phonon spectra without imaginary modes, while those with odd n are dynamically unstable. The metallic behaviors are present in the T-graphene derivatives-n with even carbon atoms in the linear carbon chains, showing an alternating single and triple C-C bonds. Besides, we observe that the metallicity of the T-graphene derivatives-n with even n becomes stronger as n increases. On the other hand, the linear carbon chains with odd carbon atoms are comprised of continuous C=C double bonds. These T-graphene derivatives-n with odd n also show metallic behaviors, but turn into magnetic materials (except for n = 1), the magnetic moments are about 0.961 mu B (n = 3) and 0.863 mu B (n = 5) respectively, and ferromagnetic ordering is the only possibility for the magnetism, which rarely occurs in carbon material. Our first-principle studies indicate that the introducing carbon chains between the tetragonal carbon rings of T-graphene constitute an efficient method to obtain new two-dimensional carbon allotrope. With different numbers (even or odd) of carbon atoms on the chains, the constructed 2D carbon allotropes could show contrasting dynamical and magnetic properties. These findings provide a theoretical basis for designing two-dimensional carbon materials and carbon-based nanoelectronic devices.National key Research and Development Program, China [2016YFA0202601];; Young Scientists Fund of the National Natural Science Foundation of; China [11605073]; Scientific Research Foundation of the Education; Department of Fujian Province, China [JAT160690