在无单位元下体现零模

本文用Horn函子刻划阿丁环．     

Kan Extensions of Internal Functors. Algebraic Approach

We investigate the question of the Kan extension in the case when all categories and functors are internal in the category of groups. Under certain assumptions we establish the necessary and sufficient conditions for the existence of internal Kan extensions. Questions related to this problem are also discussed.     

Derived Functors of Hom Relative to Flat Covers

We study the derived functors of Hom that are computed by using flat resolutions of Hom. These are denoted ⁿ. We compare these with the usual Extⁿ's and show that ¹⊂ Ext¹and indicate (using MacLane's terminology) why the class of associated short exact sequences is a proper class. When the ring is a Dedekind domain we classify the N such that ⁿ(–, N) = 0 and show that unlike the situation for other classically defined right derived functors of Hom, Hom is not balanced relative to the two classes of modules that make ¹ vanish.     

新一代航空发动机燃烧室

针对新一代高油气比(0.051及以上)航空发动机燃烧室,本文提出头部采用化学恰当比直接混合燃烧设计方案.对于新一代高压比(70及以上)低排放民用航空发动机燃烧室,由于其自着火延迟时间极短,因此采用贫油直接混合燃烧,而不能采用预混合预蒸发燃烧.本文提出了一种贫油直接混合低排放燃烧室方案,其燃油空气模由简单的压力雾化喷嘴和...     

Ding分次模和强Ding分次模

研究了分次环R上的Ding分次投射(内射)R-模以及强Ding分次投射(内射)R-模,证明了任意分次环上的Ding分次投射(内射)模类是投射(内射)可解的.研究了强Ding分次投射(内射)R-模与Ding分次投射(内射)R-模之间的关系,以及强Ding分次投射(内射)R-模与非分次的强Ding投射(内射)R-模之间的关系.证明了对有限群分次环R,若M是强Ding投射(内射)R-模,则F(M)是强Ding分次投射(内射)的;若N是强Ding分次投射(内射)R-模,则U(N)是强Ding投射(内射)的.     

Summand absorbing submodules of a module over a semiring

An R-module V over a semiring R lacks zero sums (LZS) if $x+y=0$ implies $x=y=0$. More generally, we call a submodule W of V “summand absorbing” (SA) in V if $?x,y\in V:x+y\in W?x\in W,y\in W$. These arise in tropical algebra and modules over idempotent semirings, as well as modules over semirings of sums of squares. We explore the lattice of finite sums of SA-submodules, obtaining analogs of the Jordan–Hölder theorem, the noetherian theory, and the lattice-theoretic Krull dimension. We pay special attention to finitely generated SA-submodules, and describe their explicit generation.     

拉曼光谱检测系统的搭建及在仪器分析基础实验教学中的应用*

报道了一种可由学生自行搭建的拉曼光谱检测系统,并设计了配套的实验内容,引入了前沿的表面增强拉曼光谱(SERS)技术,应用于牛奶中违法添加物三聚氰胺的检测。学生通过对仪器的组装和测试,可以更加深入地理解科学仪器的结构和工作原理,有助于提高学生的动手能力和创新思维。     

Dielectric/metal/dielectric selective reflector for improved energy efficiency of building integrated bifacial c-Si photovoltaic modules

Crystalline silicon bifacial photovoltaic modules (BFPVs), which simultaneously harvest the front- and rear-incident light, are suitable for building-integrated energy harvesting system due to their high power output and transparency. However, the lack of a rear reflector in semi-transparent BFPVs lowers their efficiency. In this study, we proposed a selective reflector (SR) with a dielectric/metal/dielectric structure to increase the power output of BFPVs and ensure a clear view through the BFPV windows. The SRs exhibit a high transmittance in the visible-light region and a high reflectance in the near-infrared (NIR)-light region. By recycling unabsorbed photons by SR, the power output of the SR-incorporated BFPVs is 13.2% higher than that of the BFPVs with bare glass. Moreover, the SR prevents the heating of the interior of buildings by reflecting the NIR light. Hence, the SR can contribute to energy efficiency of buildings.