Optimal operation of MEA-based post-combustion carbon capture for natural gas combined cycle power plants under different market conditions

Carbon capture for fossil fuel power generation attracts an increasing attention in order to address the significant challenge of global climate change. This study aims to explore the optimal operation under different market conditions for an assumed existing natural gas combined cycle (NGCC) power plant integrated with MEA-based post-combustion carbon capture (PCC) process. The steady state process models for NGCC power plant, PCC process and CO₂ compression train were developed in Aspen Plus® to give accurate prediction of process performance. Levelised cost of electricity (LCOE) is formulated as the objective function in optimization studies. Economic evaluation was carried out for the base case of the integrated system including CO₂ transport and storage (T&S). The optimal operations were investigated for the carbon capture level under different carbon price, fuel price and CO₂ T&S price. The study shows that carbon price needs to be over €100/ton CO₂ to justify the total cost of carbon capture from the NGCC power plant and needs to be €120/ton CO₂ to drive carbon capture level at 90%. Higher fuel price and CO₂ T&S price would cause a higher operating cost of running carbon capture process thus a higher carbon price is needed if targeted carbon capture level is to be maintained

Genus-2 G-function for P1P^1 orbifolds

In this paper we prove that for Gromov-Witten theory of $P^1$ orbifolds of ADE type the genus-2 G-function introduced by B. Dubrovin, S. Liu, and Y. Zhang vanishes. Together with our results in [LW], this completely solves the main conjecture in their paper [DLZ]. In the process, we also found a sufficient condition for the vanishing of the genus-2 G-function which is weaker than the condition given in our previous paper [LW].Comment: 19 pages. No figur

Connecting the Kontsevich-Witten and Hodge tau-functions by the GL(∞)^\hat{GL(\infty)} operators

In this paper, we present an explicit formula that connects the Kontsevich-Witten tau-function and the Hodge tau-function by differential operators belonging to the $\hat{GL(\infty)}$ group. Indeed, we show that the two tau-functions can be connected using Virasoro operators. This proves a conjecture posted by Alexandrov in [1].Comment: 48 page

China has reached the lewis turning point

In the past several years, labor shortages in China have become an issue. However, there is heated debate as to whether China has passed the Lewis turning point and moved from a period of unlimited supply to a new era of labor shortage. Most empirical studies on this topic focus on estimation of total labor supply and demand. Yet the poor quality of China’s labor statistics leaves the debate open. In this paper, China’s position along the Lewis continuum is examined though primary surveys of wage rates, which offer a more reliable statistic than employment data. Our results show a clear rising trend in real wage rates since 2003. The acceleration of real wages even in slack seasons indicates that the era of surplus labor is over. This finding has important policy implications for China’s future development.dual economy, employment data, Labor market, Lewis model, Supply and demand, surplus labor, wage rates,

Investigating the coordinate regulation of stem cell proliferation and differentiation by FBF proteins

Balance of stem cell proliferation and differentiation is important for maintaining tissue homeostasis, and uncovering the mechanisms regulating the balance of proliferation and differentiation of stem cells helps us understand the causative factors for ageing, cancer and various degenerative disorders. Pumilio and FBF (PUF) family RNA-binding proteins are conserved mRNA regulators controlling stem cell development in eukaryotes. FBF-1 and FBF-2, two PUF family proteins in C. elegans, are expressed in the mitotic region of the germline and are important for maintaining germline stem cells. FBF-1 and FBF-2 are very similar in primary sequence and share most of the target mRNAs, but they localize to distinct RNA granules and have different effects on target mRNAs and stem cell maintenance. This dissertation studies how FBFs mediate the coordinate regulation of germline stem cell proliferation and differentiation and the mechanisms allowing differential activities of FBF homologs in stem cells. This work has, for the first time, demonstrated that FBF-1 and FBF-2 have distinct effects on stem cell dynamics: FBF-1 restricts the rate of stem cell meiotic entry, while FBF-2 promotes both rates of proliferation and meiotic entry. Based on our findings, we propose that FBFs’ coordinate regulation contributes to maintaining the balance of stem cell proliferation and differentiation in the germline. In addition, this work has also identified CCR4-NOT deadenylation machinery as an FBF-1-specific cofactor, DLC-1 as an FBF-2-specific cofactor, and five splicing factors as potential specific cofactors for FBF-2. PUF proteins are conserved stem cell regulators in eukaryotes, from yeast to humans, and they share conserved mechanisms that affect stem cell proliferation and differentiation. This dissertation offers new mechanistic insights into PUF function in C. elegans that are likely relevant for other organisms